Low-Level Radio Frequency (LLRF) Workshop 2025

Oct 12, 2025, 8:00 AM → Oct 16, 2025, 11:45 PM US/Eastern

Newport News Marriott at City Center

Curt Hovater (JLAB), James Latshaw, Jennifer Carter, Joshua Settle, Kathy Azevedo, Tomasz Plawski (Jefferson Lab)

The biennial Low Level Radio Frequency workshop (LLRF Workshop 2025) convenes scientists and engineers worldwide, focusing on precision radio frequency systems for particle accelerators. Topics include applications in linear and circular accelerators, precision field regulation of normal and superconducting RF cavities, timing and phase reference distribution, and precision analog and digital hardware. These events are affiliated with the U.S. Department of Energy (DOE), US national laboratories, and the worldwide community of particle accelerators and associated experiments.

The Low Level Radio Frequency Workshop 2025 (LLRF Workshop 2025) will be hosted by the Thomas Jefferson National Accelerator Facility (Jefferson Lab), similar to the inaugural event in this series that began 24 years ago in 2001.

*This meeting will take place at the Newport News Marriott in City Center for Sunday-Wednesday and will be at the Jefferson Lab CEBAF Center Auditorium on Thursday.

Questions? Email: LLRF25Workshop@jlab.org

We are excited to welcome you to the 2025 LLRF Workshop!

Conference Website: https://www.jlab.org/conference/LLRF25

Information from past workshops can be found at http://llrf.net/

Local Organizing Committee:

Tomasz Plawski
Curt Hovater
Josh Settle 
James Latshaw
Admin Support: Kathy Azevedo
Event Services Manager: Jennifer Carter

Scientific Program Committee:

Alessandro Ratti (chair), Lawrence Berkeley National Laboratory
Tim Berenc, Argonne National Laboratory
Brian E. Chase, Fermi National Accelerator Laboratory-ret
Mark Crofford, Oak Ridge National Laboratory
Larry Doolittle, Lawrence Berkeley National Laboratory
Zheng Gao, Institute of Modern Physics (IMP)
Zheqiao Geng, Paul Scherrer Institut
Mariusz Grecki, Deutsches Elektronen-Synchrotron
Wolfgang Hofle, European Organization for European Research (CERN)
Curt Hovater, Thomas Jefferson National Accelerator Facility
Xiao Li, Institute of High Energy Physics (IHEP)
Toshihiro Matsumoto, The High Energy Accelerator Research Organization (KEK)
Chang-Ki Min, Pohang Accelerator Laboratory
Luca Piersanti (INFN-LNF)
Tomasz Plawski, Thomas Jefferson National Accelerator Facility
Kevin Smith, Brookhaven National Laboratory 
Dmitry Teytelman, Dimtel, Inc.
Yubin Zhao, Shanghai Institute of Applied Physics
Zeran Zhou, University of Science and Technology of China (USTC)
 

Thank you to our sponsors!

                   

      

     

 

REGISTRATION NOW OPEN!

Workshop Poster.jpg

Sun, October 12

Registration Open and Exhibitor Load In

6:30 PM Welcome Reception

Mon, October 13

Registration and Information Table Open

Light Breakfast Available

Welcome & LOC Announcements

Opening Talk

1 LLRF activities at CERN

This talk will present an overview of the ongoing and future Low-Level RF (LLRF) activities at CERN, addressing the growing challenges of hardware obsolescence, support for legacy systems, and the need for long-term consolidation across the accelerator infrastructure. Major ongoing projects, such as the development of the Crab Cavity controller with beam noise feedback for the High Luminosity LHC, the LLRF system for AWAKE Run 2c, and ongoing efforts in supporting superconducting RF cavity testing through dedicated controls infrastructure will be covered.

Going forward, LLRF studies for the Future Circular Collider (FCC) are underway, with possible co-development activities foreseen with the LHC and electron injectors. In parallel, machine learning and AI techniques are being actively investigated for applications in diagnostics, anomaly detection, and real-time control optimization.

Speaker: Ben Woolley (CERN)

Lab Talk Block

2 DESY lab talk

Overview of the latest LLRF developments at DESY. This includes a short report on XFEL and FLASH operation and upgrades. Some R&D highlights related to the preparation work towards continuous wave operation of the European XFEL and DESY's involvement with the iSAS European project (Innovate for Sustainable Accelerator Systems) will also be presented.

Speaker: Julien Branlard (DESY)

Coffee Break

3 Lab Talk - Fermilab

An update on the various projects at Fermilab including PIP-II, Mu2e , LBNF and the various test stands

Speaker: Dr Philip Varghese (Fermilab)

4 China Lab Talk

Speaker: T B D

5 JLAB talk

The presentation will highlight key LLRF developments at Jefferson Lab, including the Electron-Ion Collider (EIC) and the Proton Improvement Plan II (PIP-II).

Speaker: Tomasz Plawski (Jefferson Lab)

6 LBNL Lab Talk

This presentation will highlight LLRF activities at LBNL, covering both our accelerators, the collaborations with other laboratories and some applications beyond accelerator controls.

Speaker: Alessandro Ratti

7 Status of LLRF activities at SLAC

A status of LLRF activities at SLAC will be presented including operational accelerators and ongoing projects.

Speaker: Andy Benwell (SLAC)

8 BNL Lab Talk

This talk will review the LLRF activities at BNL for the Collider-Accelerator complex and the Electron-Ion Collider (EIC). Topics include analysis, specification and development of systems for the EIC as well as operational highlights for the Relativistic Heavy Ion Collider (RHIC) and its injector complex.

Speaker: Kevin Mernick (Brookhaven National Laboratory)

12:00 PM Lunch (not provided)

Tutorial: Cavity Low-Level RF in Hadron Machines

Convener: Dr Themis Mastoridis (California Polytechnic State University)

9 Multiharmonic enthusiast -- Applications of multiharmonic feedback in synchrotrons

Magnetic alloy (MA) cavities have wideband frequency responses, which allow multiharmonic rf voltage excitation in a single cavity. In the low level rf (LLRF) control system for the Japan Proton Accelerator Research Complex (J-PARC) Rapid Cycling Synchrotron (RCS) the multiharmonic vector rf voltage control feedback is implemented to realize the dual harmonic rf operation for bunch shaping and to compensate of the multiharmonic beam loading. The multiharmonic feedback consists of several classical IQ feedback blocks, and the RCS system has eight feedback blocks. Similar feedback systems are employed for the other proton synchrotrons, such as CERN PSB and CSNS. The possible application of multiharmonic feedback is not limited to bunch shaping using dual harmonic. Using triple harmonic operation, we can generate more flat rf buckets for realization of flatter bunches. Ultimately, barrier buckets can be generated using many harmonics. Other interesting application is generating a non-integer harmonic rf with several harmonics, which can be used for butch compression. In the presentation, we will explore these possible applications. We will also discuss important considerations when using multiharmonic feedback. One must be careful about the frequency response of the cavity voltage monitor to adjust the precise harmonic voltages. Another point is that unwanted cavity voltage jump may happen after fast extraction of a high intensity beam.

Speaker: Fumihiko Tamura (Japan Atomic Energy Agency, J-PARC Center)

System and Operations Block 1

10 High-Precision LLRF System for the upgrade of SXFEL

A high-performance low-level radio frequency (LLRF) control system based on ZYNQ MPsoc has been developed to enable the digital and intelligent upgrade of Shanghai Soft X-ray Free-Electron Laser (SXFEL). It includes 8 channels of 310 MSPS 16-bit ADCs and 2 channels of 500 MSPS 16-bit DACs, capable of outputting continuous wave and pulse wave signals, respectively. The LLRF control system is equipped with an FMC(LPC) interface to communicate with the White Rabbit(WR) device in the control system, providing feedback on the SXFEL' s orbit, focusing, and beam energy states. In experimental measurements on SXFEL, the LLRF system achieves a amplitude stability of 0.016% (RMS) and a phase stability of 0.015o at pulse compressor output.

Speaker: CHENGCHENG XIAO (SHANGHAI ADVANCED RESEARCH INSTITUTE)

11 Reverse phase operation for CERN's FCC-ee 400 MHz RF system: Increasing flexibility brings challenges for cavity control

CERN's planned Future Circular electron-positron collider (FCC-ee) must accommodate very different RF system requirements at different energy points, driven by a fixed synchrotron radiation power budget of 100 MW. Recently, a unified RF cavity design with constant loaded quality factor suitable for three beam energies (45.6, 80, and 120 GeV) was adopted as the baseline. The new RF system implementation requires the inclusion of the reverse phase operation (RPO) scheme for the Z operating point (45.6 GeV). In this contribution, the main principles of the RPO scheme are first explained. The need to mitigate the enhancement of transient beam loading due to the RPO scheme is described, along with the corresponding LLRF and HLRF requirements to achieve precise control of the cavity field. Finally, the dynamics of the beam and RF system in the event of RF system failures are analyzed, including a detailed implementation of LLRF loops and interlocks.

Speaker: Ivan Karpov (CERN)

12 Overview of Electron Ion Collider RF Systems

Brookhaven National Laboratory (BNL) is the future home of Electron-Ion Collider (EIC) project that will be constructed in partnership with Thomas Jefferson National Accelerator Facility (Jefferson Lab, JLAB). The EIC proposal provides a design that utilizes the existing RHIC facility to produce hadron beams, including high-intensity polarized proton beams, to fully meet the requirements for a lasting research program with high potential for new discoveries. It is also planned as a cost-effective new facility with approximately 30 SRF cryomodules and 55 NCRF cavities that includes reuse of RHIC 28 MHz and 197 MHz cavities. Many systems are still developing but plenty of progress has been made on EIC RF Systems since it was last presented at LLRF Workshop 2022. The scope of the RF systems as currently defined at pre-construction design phase of the EIC project will be presented.

Speaker: Geetha Narayan (Brookhaven National Laboratory)

Coffee Break

13 Development of new DLLRF for ALBA and ALBAII, for the main and for the 3rd harmonic RF systems

ALBA Low-Level RF (LLRF) system has provided over a decade reliable operation and has been adopted by other synchrotron facilities. To meet the evolving requirements of ALBA and ALBA-II, a new LLRF system has been developed for the current fundamental RF system and the future active normal conducting harmonic RF system. This new LLRF features FPGA and ADC/DAC µTCA boards designed by Safran, enabling direct 500 MHz signal sampling without down/up-conversion for the main RF system, while it requires an intermediate frequency in the case of the harmonic system performed in the RTM board itself. These enhancements reduce system complexity, minimize noise, and simplify maintenance. Safran also supplies peripheral modules and the Tango device server generator, while ALBA implemented it and developed a new GUI. Upgraded Digital and RF signal front-ends complement the new hardware. The legacy VHDL code has been updated to improve readability and functionality, incorporating advanced features such as octant selection and a harmonic direct feedback selection method. The latter, based on IIR filtering, isolates positive and negative revolution harmonics in the I/Q domain, feeding them back to amplifiers to effectively mitigate transient beam loading caused by the storage ring bunch train gaps. This upgraded LLRF system delivers enhanced performance and greater flexibility to address the future needs of ALBA and ALBA-II.

Speaker: Pol Solans (ALBA Synchrotron)

14 Achieving Ultra-Stable RF Control for Plasma Acceleration at LNF-INFN

The SPARC_LAB facility at LNF includes a high-brightness electron linac dedicated to plasma acceleration studies and R&D. Given the stringent stability requirements on electromagnetic fields, especially for particle-driven plasma acceleration, several upgrades have been implemented over the past two years to enhance RF stability and measurement accuracy. In 2024, the low-level RF system was completely refurbished, replacing the original analog systems with digital ones featuring temperature-stabilized front ends and arbitrary pulse shaping capabilities. Additionally, the intra-pulse phase feedback, originally commissioned in 2008 for the S-band klystrons, was upgraded. A new RF design, along with improved error amplifiers and signal acquisition electronics, was deployed and first tested on the machine in Fall 2024. Comprehensive short- and long-term measurements performed at SPARC_LAB confirm the system's ability to reliably and reproducibly reduce S-band klystron phase jitter down to 15 fs rms. The obtained results are now very close to the 10 fs limit demanded by plasma acceleration and represent a promising step toward meeting the requirements of future accelerator facilities.

Speaker: Luca Piersanti (INFN-LNF)

15 New RF control system developments at LNF-INFN

SPARC_LAB is a high-brightness e-beam for SASE-FEL (self-amplified spontaneous emission-FEL) experiments. It consists of a brazeless 1.6-cell S-band RF gun, two travelling wave S-band accelerating structures each 3 meters long, and a 1.4-meter C-band structure that acts as an energy booster. As part of the SABINA project, co-funded by the Lazio Regional Government for consolidation of SPARC_LAB, a significant upgrade of the RF control systems was completed last year. The activity involved the development of software for remote control of LLRF systems, C-band modulator, as well as custom hardware made by the RF service for fast feedbacks and RF synchronization. Algorithms were also developed for statistical and diagnostic analysis of RF signals, with real-time amplitude and phase jitter monitoring capabilities. Development of a custom EPICS application aimed at optimizing system resources is currently underway. Finally, to support conditioning operations, dedicated software has been implemented for automatic RF plant management, which dynamically adjusts RF power and manages interlocks under critical conditions.

Speaker: Beatrice Serenellini (INFN - LNF)

16 APS-Upgrade Digital LLRF Systems Summary*

Various digital low-level radiofrequency (LLRF) systems are now operating for the Advanced Photon Source Upgrade (APS-U). This includes a passive superconducting bunch-lengthening cavity LLRF system primarily used for quench detection and signal monitoring of both the cavity and beam. The original analog-based LLRF systems for the klystron-driven main accelerating cavities were kept intact. However, a digital 60-Hz-harmonic-related rf noise suppression (RFNS) system was added to suppress noise from the megawatt-class klystrons which leads to beam motion. Additionally, within the injectors, the Particle Accumulator Ring was upgraded to digital LLRF for improved control. This report summarizes the systems and shares operational experience with beam.

• Work supported by U. S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357

Speaker: Tim Berenc (Argonne National Laboratory)

17 Seven Years of RF Fault Identification at JLAB

The digital low level RF systems that are used to operate 17 of the 53 cryomodules that are installed in CEBAF have the capability to log 17 waveforms either on demand or when one of the cavities in the cryomodules trips off. In 2018, the software and hardware in the digital low-level RF systems was configured such that a fault would trigger an acquisition process to record 17 RF waveform signals for each of the 8 cavities within the cryomodule for subsequent analysis. To date approximately 15,000 faults have been analyzed. This contribution will describe the types of faults encountered during operation and their signatures in the time domain data, as well as how it is being used to modify the setup of the machine and implement improvements to the cryomodules.

Speaker: Mr Tom Powers (JLAB)

Tue, October 14

Registration and Information Table Open

Light Breakfast Available

Welcome & LOC Announcements

System and Operations Block 2

18 The progress of LLRF control system for SC linac in IMP

The large scientific and technology facility of CiADS and HiAF, which powered by superconducting linac is under construction, and faces many technological challenges. The low level RF control system has been developed for these science and technology infrastructures for several years, and some new technology has been adopted to enhance the performance and flexibility of hardware, software and system integration. As a fully tested system, the LLRF control system has begun large-scale use online, the progress of development and research results will be reported in this presentation.

Speaker: Zheng Gao

19 Compensating for Amplifier Non-Linearity in a SEL Controller

The SEL architecture used commonly in CW superconducting linacs is a positive feedback system that requires determining the correct limits for the operating conditions to ensure stable operation. These limits are determined from the results of the amplifier calibration which characterizes the dac drive(forward power) against the cavity field. When the amplifier non-linearity precludes a simple linear fit for this characteristic, its modification to account for the amplifiers non-linearity is essential to operate the system in the SEL architecture. This process is described with test data from a 32kW SSA for the PIP-II linac.

Speaker: Shrividhyaa Sankar Raman (Fermilab)

20 Operational Experience with the Proton Power Upgrade Low-Level RF Control System

The Proton Power Upgrade (PPU) Project was recently completed for the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory and has doubled the proton beam power capability from 1.4 MW to 2.8 MW with 2 MW beam power available to the first target station. A second target station project is under development to utilize the remaining beam power. The SNS has completed the first operational periods with the full complement of PPU hardware utilized. For the PPU, twenty-nine new MicroTCA-based LLRF control systems were installed to solve the obsolescence issues with the existing systems and to add capabilities required for the future second target station. The controls software for the LLRF system was rewritten to take advantage of the new features available. The performance of the new control systems, along with minor corrections to the systems will be presented.

Speaker: Mark Crofford (Oak Ridge National Laboratory)

21 LLRF Progress at FRIB: from Commissioning to Operation and Future Directions

The Facility for Rare Isotope Beams (FRIB) was fully commissioned in 2021 and began user operations in May 2022. This talk provides an update on Low-Level Radio Frequency (LLRF) system activities at FRIB during the transition from commissioning to routine operation. Key efforts have focused on spare parts management and the development of advanced troubleshooting tools to support reliable system performance. We present operational insights from the early stages, including achieved performance metrics, system uptime, lessons learned, automation of cavity turn-on/off, conditioning, auto-restart process and beam based feedback for LLRF energy and phase regulation. Additionally, we briefly introduce ongoing developments of a new LLRF hardware platform designed to support future FRIB upgrade cavities.

This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics and used resources of the Facility for Rare Isotope Beams Operations, which is a DOE Office of Science User Facility under Award Number DE-SC0023633.

Speaker: Shriraj Kunjir (Facility for Rare Isotope Beams)

Coffee Break

22 LLRF System Analysis for the Fermilab PIP-II Superconducting LINAC

PIP-II is a superconducting linac that is in the initial acceleration chain for the Fermilab accelerator complex. The RF system consists of a warm front-end with an RFQ and buncher cavities along with 25 superconducting cryo-modules comprised of cavities with five different acceleration β. The LLRF system for the linac has to provide field and resonance control for a total of 125 RF cavities. Various components of the LLRF system have been tested with and without beam at the PIP-II test stands. The LLRF system design is derived from the LCLS-II project with its self-excited loop architecture used in the majority of the cryo-modules. The PIP-II beam loading at 2 mA is much higher than LCLS-II linac. The control system architecture is analyzed and evaluated for the operational limits of feedback gains and their ability to meet the project regulation requirements for cavity field amplitude and phase regulation.

Speaker: Dr Philip Varghese (Fermilab)

SRF Controls Block

23 Piezo compensation algorithm for SC cavities at ESS

The 3 ms long RF pulse at ESS will make Lorentz force detuning (LFD) significant for the superconductive cavities and at 14 Hz repetition rate some ringing might still be present at the start of the next pulse. An iterative compensation algorithm have been developed to reduce the required overhead to maintain a constant cavity field. It is based on detuning calculation of each pulse and provides a voltage to the Piezo stack to counteract LFD. Design details and initial results will be presented.

Speaker: Anders Svensson (European Spallation Source)

24 A Universal Cavity Controller for testing SRF cavities at CERN

As the use of SRF cavities continuously increases at CERN, testing facilities are also being upgraded. Due to the variety of operating frequencies, ranging from 400 MHz to 1.3 GHz, a generic cavity controller has been designed implementing Generator Driven (GD) and Self-Excited Loop (SEL) modes. A modern approach for separating gateware, embedded firmware (micro-controller unit) and low-level software, as well as Continuous Integration (CI) for automatic bitstream generation and simulation have been used in the Universal Cavity Controller (UCC). Additionally, the UCC development is planned to be applied in MicroTCA architecture in the framework of a project for axion detection using a SRF cavity.

Speaker: Diego Barrientos (CERN)

25 SRF Controls Talk - To Be Determined

12:10 PM Lunch (not provided)

Tutorial: Amplifier Additive Phase Modulation Noise Characterization and Testing & Theoretical Discussion of White and Flicker Noise Processes in Small and Large Signal Regions of Operation

Convener: Joseph Merenda (Mini-Circuits)

26 Initial commissioning of the new beam control system of the Proton Synchrotron at CERN

The Proton Synchrotron (PS), CERN’s first synchrotron, delivers proton and ion beams with intensities covering almost four orders of magnitude using 25 RF cavities with frequencies ranging from 0.4 to 200 MHz. The LLRF system includes multi-harmonic feedback loops to control the field in the cavities and beam-based loops to perform complex beam manipulations. The current beam control system is implemented using a mix of analog and digital hardware, suffering from obsolescence and reproducibility issues. The new fully digital system, implemented in VMEbus Switched Serial (VXS) and MicroTCA platforms, is currently in its initial commissioning phase. This work presents a complete description of the new beam control system as well as the first results of the initial commissioning phase in the machine.

Speaker: Diego Barrientos (CERN)

System and Operations & Hardware Poster Session

Conveners: Diego Barrientos, Hyojae Jang, James Latshaw, Jing Chen, Jinyul Hu, Joel Axel Wulff, Joshua Settle, Kevin Mernick, Lennon Reyes, Luca Piersanti, Maciej Grzegrzolka, Matei Guran, Michael Geesaman, Michael McCooey, Nashat Sawai, Paula Van Rooy, Qiang Du, Sangyoon Bae, Shreeharshini Dharanesh Murthy, Shrividhyaa Sankar Raman, Wanming Liu, Yubin Zhao, Zhigang Zhang

27 Status of a LLRF System for RAON Low Energy LINAC

RAON is a heavy ion accelerator complex in Daejeon, Republic of Korea. Its beam commissioning of low energy superconducting linear accelerator (SCL3) have been finished by Institute for Rare Isotope Science (IRIS) in Institute of Basic Science (IBS). The purpose of this accelerator is the generation of rare isotope by ISOL (Isotope Separation On-Line) and its acceleration for the nuclear physics experiment. SCL3 consists of 22 quarter wave resonator (QWR) type cavities and 102 half wave resonator (HWR) type cavities and their operating RF frequencies are 81.25 MHz and 162.5 MHz. Every cavity can be controlled independently for the flexibility to accelerate the various A/q ions. The development, evaluation and installation of the digital LLRF based on the FPGA technology have been finished in 2022. The self-excited loop (SEL) and the generator-driven-resonator (GDR) algorithm are implemented and they are being used for the accelerator operation. In this presentation the status of RAON LLRF and some preliminary research result related to its upgrade will be described.

*This work was supported by the Institute for Basic Science(IBS-I001-D1)

Speaker: Hyojae Jang (Institute for Basic Science)

28 EIC Resonance and Interlocks Control

The Electron Ion Collider project is a large and exciting effort within the accelerator community. There will be 8 different styles of Cryomodule and as many varied styles of normal conducting cavities. All of these modules require interlock protection and most require some form of resonance control. This abstract presents the ongoing efforts at Jefferson Lab to develop a modular system which can scale in accordance to a cavities resonance and interlock control needs; thereby reducing the number of different styles of resonance and interlocks control chassis required and consolidates the interface controls to one common system. The immediate benefit is reduced cost in manufacturing and the long term benefit will be in simplified support for common shared spares.

Speaker: Mr James Latshaw (JSA)

29 Status of LCLS-II-HE LLRF Project

The LCLS-II-HE project is a high-energy upgrade to the existing LCLS-II superconducting linac at SLAC, designed to increase the beam energy from 4 GeV to 8 GeV. This upgrade includes the addition of 184 high-energy (HE) SRF cavities operating at an average gradient of 22 MV/m, supplementing the 280 existing LCLS-II SRF cavities. To support these new cavities, the HE LLRF project will deploy 46 LLRF rack systems to provide precise RF field regulation—meeting amplitude and phase stability requirements of 0.01% and 0.01° RMS, and resonance control to maintain average cavity detuning below 1 Hz. This paper presents an overview of the HE LLRF project status, reviews system updates, and discusses readiness for the upcoming LLRF installation and checkout, along with key lessons learned throughout the project lifecycle.

Speaker: JING CHEN (SLAC)

30 Reliable operation of PAL-XFEL LLRF

The PAL-XFEL LLRF and SSA systems have contributed to the stable operation of PAL-XFEL for nearly a decade with their reliability and robustness. Key achievements of these systems include the development of pulse-by-pulse real-time RF switching function for simultaneous operation of the HX and SX beamlines, development of a converter-type X-band LLRF, and development of a function to improve RF amplitude drift. The systems have faced various challenges during their operation, such as the arrival of key component life cycles, the discontinuation of key components, and the need for upgrades to keep pace with technological advances. Therefore, the following activities are being pursued. The PAL-XFEL LLRF and SSA systems have been field-proven, so upgrades are being carried out based on the existing systems. The discontinued processing PCs have been upgraded to higher-performance industrial boards, the RF modules are being redeveloped, and the A/D and FPGA boards are planned to be upgraded with new FPGAs and PCIe. In addition, an updated SSA prototype has been developed.

Speaker: Jinyul Hu (Pohang Accelerator Laboratory (PAL))

31 Anomaly Detection in the CERN Proton Synchrotron RF Systems Using Machine Learning

The CERN Proton Synchrotron (PS) is equipped with several RF systems covering a wide range of revolution frequency harmonics. While the beam synchronous RF signal generation and cavity controllers are mostly digital, the global low-level RF beam loops still rely on analogue hardware. Upgrades to a fully digital system are underway.

Digitizing additional key signals from the present beam control recently enabled the exploration of automated monitoring methods. Subtle RF issues such as parameter drifts and intermittent anomalies often go undetected, delaying diagnosis until beam quality degrades or operation is disrupted. To address this, we investigate machine learning-based anomaly detection models that aggregate information from low-level RF signals, beam diagnostics, and contextual data (e.g. magnetic field). These models seek to automatically detect abnormal behaviour and connect beam effects with underlying causes linked to the RF systems, supporting both real-time alerts and root-cause analysis.

This proactive, data-driven approach aims to shorten the response time to performance degradation, improve reliability, and support preventative maintenance of the PS RF systems.

Speaker: Joel Axel Wulff (CERN)

32 Local Oscillator Conditioner for the Electron Ion Collider

The Electron Ion Collider is an exciting collaborative effort to advance and invest in the future of nuclear physics and accelerator science. Part of this great effort includes designing a diverse set of RF cavities and control systems, in which heterodyning still plays a fundamental role. There are multiple frequencies in the VHF and UHF bands which require up and/or down conversion, and designing one circuit board that can accommodate local oscillator signals for multiple mixing schemes was a valuable and interesting task. A combinatorics problem emerged out of this component’s constraints that required organizing a large number of cases and integrating commercial data to reveal the best design choices. Pictures of the prototypes and their performance are displayed to demonstrate its success. This poster showcases only part of the vast and impressive collaboration between Brookhaven National Laboratory and the Thomas Jefferson National Accelerator Facility.

Speaker: Joshua Settle (Jefferson Lab)

Local Oscillator Conditioner for EIC.pptx

33 Design of the Electron-Ion Collider Common Platform and Applications for RF Controls

The EIC Common Platform is a modular system architecture which will serve as the basis for EIC Accelerator Controls. It consists of an SoC-based carrier board with up to two independent pluggable FPGA-based Daughtercards. Different types of Daughtercards have custom electronics catering to the specific needs of an application. Daughtercards will have FPGA logic to support a common protocol for communication with the carrier board as well as a basic set of features for programming and telemetry. RF Controls applications will use two versions of an RF Digitizer Daughtercard designed by the LLRF team as well as several of the general purpose Daughtercards designed in collaboration by the LLRF, Accelerator Controls, and Instrumentation groups. The system architectures for various LLRF applications using the Common Platform components will be presented.

Speaker: Kevin Mernick (Brookhaven National Laboratory)

34 Warm Front End upgrade for the PIP-II Linac

The warm front end for the PIP-II linac consists of an Ion-source an RFQ and four buncher cavities. The LLRF systems for these were the first ones developed more than a decade ago for use at the test stands. Some were VXI crate based and others used early generation FPGA boards that are light in resources. These LLRF systems and the one for the first superconducting cryomodule, the HWR will be upraded with the ARRIA10 SOCFPGA chassis with EPICS interfaces like the rest of the PIP-II Linac. The RFQ and the HWR have unique resonance control systems which are integrated into the LLRF controller hardware. The results of the initial testing with a cavity emulator will be presented.

Speaker: Lennon Reyes (Fermilab)

35 Design, characterization and commissioning of X-band LLRF systems for the TEX RF upgrade at LNF-INFN

The TEX (Test-stand for X-band) facility at LNF-INFN was established in 2021 and commissioned in 2022. It serves as an R&D center for X-band technology, supporting activities from waveguide component design and high-power testing to low-level RF (LLRF) system development. TEX is equipped with a 50 MW X-band klystron (CPI, USA) powered by a K400 solid-state modulator (ScandiNova, Sweden), operating at a 50 Hz repetition rate. It was recently upgraded with two additional RF high-power sources: a 25 MW, 400 Hz X-band unit and a 20 MW, 400 Hz C-band unit, both manufactured by Canon. This upgrade required a complete redesign of the X-band LLRF system, now featuring: (i) three C-band Libera LLRF systems (Instrumentation Technologies, Slovenia); (ii) an up/down converter, for frequency translation to the European X-band (11.994 GHz); (iii) a reference distribution system, for coherent frequency reference delivery across all the facility sub-systems. The whole LLRF system has been successfully designed, tested and installed at TEX in spring 2025. We report here the first experimental results from low power commissioning started in June 2025.

Speaker: Luca Piersanti (INFN-LNF)

36 Minimum-Latency Optical Data Acquisition Link (Modal)

The European Spallation Source (ESS) beam instrumentation generates over 100 gigabytes of data per second from over 100 subsystems along the whole ESS linac. Currently, the data is only processed locally. The development of machine learning techniques and hardware created an opportunity to allow complex analysis of the data coming from the whole accelerator. Such analysis can bring benefits to the accelerator operation and improve its reliability.
The main aim of the Modal project is to collect the data from all beam instrumentation subsystems and send it to the central processing unit. This challenging task will be solved using dedicated hardware and firmware components.
This contribution presents the Modal concept and planned architecture with performance measurements, status and plans for the near future.

Speaker: Maciej Grzegrzółka (Warsaw University of Technology, Institute of Electronic Systems)

37 Update on the Fermilab Mu2e LLRF System

The LLRF system for the Mu2e project shares the same primary LLRF hardware as the Muon g-2 experiment which concluded its run last year. Commissioning of the subsystems for the Mu2e experiment is starting this year.The RF components for this system are located at large distances from the LLRF controller. 2.5 MHz beam bunches from the Recycler are transferred to the delivery ring into 2.36 MHz buckets for resonant extraction to the Mu2e beamline. The LLRF hardware is being upgraded to a larger FPGA board and additional functions such as the drivers for the AC dipole extinction magnets are being added to the system. A local FPGA controller chassis is being used to digitize the cavity signals and to co-ordinate the beam transfer manipulations. The system architecture is described and the results of the initial
testing presented.

Speaker: Matei Guran

38 LLRF COMMISSIONING OF THE CEBAF C75 UPGRADES SAM 2024/2025

One easily overlooked component of Low-Level Radio Frequency (LLRF) design is the commissioning of new system installations. During Jefferson Lab’s (JLab) 2024 Scheduled Accelerator Maintenance (SAM), two CEBAF zones were upgraded with C75 Cryomodules and JLab’s LLRF 3.0 system. JLab’s team has invested heavily in the automation and standardization of their commissioning process. Several key components of this process include verification of the interlocks, klystron characterization and cavity characterization. This poster will present a summary of LLRF commissioning at JLab.

Speaker: Michael Geesaman

39 The Development of an Ultra-Low Phase Noise Source for Electron-Ion Collider Crab Cavities

The Electron-Ion Collider (EIC) is a long-term project to design and construct a facility to collide high energy polarized electron beams with polarized proton and heavy ion beams at center of mass energies from 20 to 140 GeV with luminosity up to 1034 cm-2s-1. This facility will be built on top of the Relativistic Heavy Ion Collider (RHIC), Brookhaven National Laboratory’s current operational high energy collider. In order to achieve the high luminosity outlined in the EIC’s design, Crab Cavities will be used around Interaction Points to correct for geometric effects due to crossing angles. These cavities have extremely strict phase noise requirements that are challenging to achieve (< -151 dBc/Hz at a 10 kHz offset from a 197 MHz Carrier). In order to meet these requirements, a low noise 2 GHz clock was designed using a 100 MHz OCXO. The 100 MHz OCXO was then locked to a separate low noise 100 MHz clock using an analog PLL to further reduce close in phase noise. This clock was then used with a low noise DAC (AD9164) to generate an RF drive signal at various frequencies of interest.

Speaker: Michael McCooey (Brookhaven National Laboratory)

40 Modernizing SLAC’s NC LINAC LLRF System with the LEMP Platform

The Linac Electronics Modernization Plan (LEMP) replaces the aging CAMAC-based low-level RF (LLRF) controls in SLAC’s normal-conducting LINAC. The new system is based on the open-source Marble FPGA carrier and Zest+ digitizer, with a custom RF front end. A prototype has been deployed and tested at station 26-3, demonstrating key functionality including RF control, interlocks, and waveform capture. Development continues on hardware integration, firmware, and CI/CD workflows. This is a preliminary submission describing current status and upgrade plans.

Speaker: Nashat Sawai (Stanford Linear Accelerator Center (SLAC))

41 Future Upgrades to the LANSCE Accelerator

The Los Alamos Neutron Science Center (LANSCE) Accelerator is in the initial planning stages to upgrade the front-end of LANSCE, a project known as the Los Alamos Modernization Project (LAMP). As a part of this upgrade the Low-Level Radio Frequency (LLRF) team will be replacing most of their equipment. This involves removing and installing new equipment related to the sources, injectors, low energy beam transport (LEBT), radio-frequency quadrupole (RFQ), medium energy beam transport (MEBT) and the drift-tube linac (DTL). Additionally, a test accelerator will be built to demonstrate the proof of concept for the new systems before removing the front-end of LANSCE. This poster will present the current status of the initial planning of the LAMP project, LLRF’s approach to LAMP, the proposed timeline and goals of the LAMP project.

Speaker: Paula Van Rooy (Los Alamos National Laboratory)

42 LLRF system upgrade of Argonne Wakefield Accelerator Facility

In collaboration with the Berkeley Accelerator Controls and Instrumentation Program, the Argonne Wakefield Accelerator Facility successfully completed an upgrade of its Low-Level Radio Frequency (LLRF) system using the LCLS-II LLRF platform. This poster will present the details of the upgrade.

Speakers: Qiang Du (Lawrence Berkeley National Laboratory), Wanming Liu (Argonne National Lab)

43 Development of LLRF-Controlled LDMOS-Based Solid State Power Amplifiers in a Heavy Ion Accelerator

The construction of a heavy ion accelerator facility is underway to support a variety of scientific studies, including nuclear physics, materials science, and medical applications. The accelerator is divided into two main sections: SCL3 for low-energy acceleration and SCL2 for high-energy acceleration. Currently, beam extraction and application experiments are being conducted in the low-energy acceleration section, while the construction of the high-energy acceleration section is ongoing. SCL3 consists of 22 quarter-wave resonators (QWR) operating at a superconducting cavity frequency of 81.25 MHz and 102 half-wave resonators (HWR) operating at 162.5 MHz. In contrast, SCL2 is equipped with 213 single-spoke resonators (SSR), which operate at a frequency of 325 MHz. The SCL3 superconducting cavities are powered by a solid-state power amplifier (SSPA) based on LDMOS (Lateral Double Diffused Metal Oxide Semiconductor) technology, capable of supplying up to 4 kW of RF power to the acceleration cavities. The primary components of the SSPA include the main transistor, a bidirectional coupler for monitoring RF input power, an attenuator, a limiter to prevent over-input, an ultra-short MMIC, a driving amplifier, a 4-way input power divider, a 4-way output power combiner, a circulator, and a dummy load. This device applies a feedback system using LLRF.

Speaker: Sangyoon Bae (IBS / IRIS)

44 Comparative Evaluation of Xilinx RFSoC Platform for Low-Level RF Systems

The rapid advancement of Radio Frequency System-on-Chip (RFSoC) technology from Xilinx (AMD) has enabled the integration of high-speed data converters and programmable logic within a single package. RFSoC platforms are already widely adopted in telecommunications, radar, and satellite communications, where they promise reductions in system footprint and power consumption. However, their suitability for Low-Level RF (LLRF) control systems in accelerator environments—where stability requirements are critical—has not been quantitatively evaluated. This paper presents a comparative measurement-based assessment of RFSoC-based and conventional LLRF designs, focusing on signal fidelity, phase noise, latency, system complexity, and integration challenges. The advantages and challenges of adopting RFSoC-based direct conversion architectures are discussed, providing guidance for future LLRF system implementations.

Speaker: Shreeharshini Dharanesh Murthy (Lawrence Berkeley National Laboratory)

45 Testing the DAE LLRF system with a PIP-II SSR2 Cavity

The PIP-II linac is an international collaboration project with in kind contributions of key subsystems from multiple countires including India(DAE). In the research and development phase of the project, the LLRF and resonance control systems were jointly developed by BARC and Fermilab and were delivered to Fermilab for testing and validation. Initial testing of the LLRF system was carried out using Fermilab’s analog cavity emulator. Following successful emulator testing, the LLRF system was deployed at STC on a PIP-II 325 MHz SSR2 cavity. The cavity was operated in both SEL and GDR modes at a gradient of 5 MV/m. The results of the testing are presented here.

Speaker: Shrividhyaa Sankar Raman (Fermilab)

46 RF commissioning at SHINE injector

The SHINE injector consists of an electron gun, a bunching cavity, a single-cavity cryo-module, and an 8-9 cell cryo-module. It has now completed commissioning, with an output energy of 100 MeV and an energy jitter of 0.003% (RMS). The amplitude and phase control accuracy of all RF acceleration structures have met the design specifications.

Speaker: Yubin zhao (Shanghai Advanced Research Institute. CAS)

47 LLRF for the L-Band Buncher in SHINE

In the Hard X-ray Free Electron Laser (SHINE), the normal-conducting L-band buncher is critical for compressing electron bunches, significantly improving beam quality to meet stringent low-emittance and low-energy-spread injection requirements. Due to its 2-cell structure, a digital LLRF control system which based on an FPGA and RF front-end architecture using I/Q demodulation was designed. This system implements amplitude/phase feedback, frequency tuning, and multi-motor coordination for field flatness control. During 10kW continuous-wave (CW) operation the amplitude stability (peak-to-peak) improved from ±0.17% in open-loop to within ±0.03% under closed-loop, while the phase stability (peak-to-peak) was controlled within ±0.05°,and field flatness was maintained within ±2%, fully meeting design specifications. This achievement is critical for ensuring high-stability accelerator operation.

Speaker: Zhigang Zhang

IQ Award Ceremony and Presentation

Measurement and Controls Block 1

48 RF Phase Drift Measurements Using Two-tone Scheme

Modern linear accelerators require more precise phase drift stability of RF reference signals. Various stabilization schemes were developed to ensure proper phase stability. This contribution presents the preliminary results of a novel two-tone-based RF signal phase drift measurement system intended to be used in the PIP-II Beam Instrumentation Phase Reference Line (BIRL). The presented test system achieved an excellent temperature coefficient of just 0.67 fs/°C.
The system operating principle will be explained. This will be followed by a description of the assembled test system and its performance measurement. The final part presents the plans for further and preliminary BIRL system architecture.

Speaker: Maciej Grzegrzółka (Warsaw University of Technology, Institute of Electronic Systems)

49 Development of the FPGA Based Digital Signal Component Separator for the LANL Solid-State Power Amplifier

Because of the aging, and product discontinuity, LANSCE is investigating the replacement of klystrons . One of the highly promising amplifiers are the GaN amplifiers. Currently available GaN amplifier can produce 5kW pulse RF power. Hence, a multitude of Solid-State Power Amplifiers (SSPA) combined together to produce the equivalent or better performance than the klystron. For a high drain voltage, the drain power dissipation is increased as the operating efficiency becomes low. In order to operate the SSPA at high efficiency, the operating of the amplifier is as close as possible to the saturation region of amplifier’s amplitude characteristic curve. The outphasing technique provides this requirement of the SSPA operation. The outphasing amplifier converts the Amplitude Modulation-Phase Modulation(AM-PM) signal to two constant envelope PM signals, so that each amplifier of two signal path linearly amplifies constant envelope PM input signals. The combiner combines two amplified PM signals, yielding the signal of linear amplification of the input signal. The core part of the outphasing amplifier is the signal component separator(SCS) in which the AM-PM input signal is converted to two constant envelope PM signals.
Most SCS techniques are implemented on the analog circuits in polar coordinate(amplitude-phase domain). In this paper, a digital signal component separator (DSCS) in In-phase/Quadrature(I/Q) coordinate is proposed. The DSCS is implemented on the present Field Programmable Gate Array(FPGA) based LANSCE digital low level RF (DLLRF) control system. The performance of the DSCS is verified on a low power teststand and the results are reported.

Speaker: Michael Brown (LANL)

50 Fault Prediction and Diagnosis for SRF Systems–Focus on RF Power Source Failures

This research aims to develop an efficient and reliable fault detection method for radio frequency (RF) superconducting cavity system power sources. Superconducting cavities are core components of large-scale scientific facilities such as particle accelerators and synchrotron radiation light sources, and their stable operation is crucial for successful experiments. However, as a key component driving superconducting cavities, potential faults in RF power sources can lead to system performance degradation or even interruption. Traditional fault detection methods often rely on manual experience or simple threshold judgments, which suffer from low detection accuracy, poor real-time performance, and difficulty in handling complex fault modes.

This abstract proposes an intelligent fault detection framework based on machine learning, designed to overcome the limitations of traditional methods. The method first involves real-time data acquisition of critical operating parameters of the RF power source, such as output power and LLRF output. Subsequently, through feature engineering on these multi-dimensional data, effective features that can characterize the system's health status are extracted. During the fault detection model training phase, a combined strategy of supervised learning and unsupervised learning will be employed. For known fault types, classification models such as support vector machines will be constructed for precise identification; for unknown or novel faults, anomaly detection algorithms such as local outlier factor will be utilized for real-time early warning.

Experimental validation on CAFe2 demonstrates that this method can detect power source faults 15 days in advance. The research provides effective technical support for the predictive maintenance of SRF systems, enhancing the operational reliability and efficiency of large-scale scientific facilities.Compared to traditional methods, this intelligent fault detection system exhibits stronger adaptability and robustness, effectively reducing system downtime and ensuring the stable operation of large-scale scientific facilities. This research provides new insights for the predictive maintenance and intelligent management of RF superconducting cavity system power sources.

Speaker: Jiayi Peng (Institute of Modern Physics)

Software Block

51 RF modeling of EM cavity resonator in Simulink

The presentation showcases RF modeling techniques for designing a digital twin of electromagnetic cavity resonators in Simulink. A comprehensive workflow includes:
• RF data analysis
• system design
• budget analysis
• simulation of RF-controlled components at the system level
Simulink offers a unified environment for seamlessly integrating RF chains with digital signal processing algorithms and control logic in feedback and feedforward configurations.
Through simulation-driven insights, the session highlights how engineers can model, analyze, and refine resonant cavity performance using digital twin strategies, accelerating development and boosting system reliability in RF applications.

Speaker: Temo Vekua

Wed, October 15

Registration and Information Table Open

Light Breakfast Available

Welcome & LOC Announcements

Measurement and Controls Block 2

52 Noise feedback system for Crab Cavities in Large Hadron Collider

Superconducting RF crab cavities will be implemented in the upcoming High-Luminosity LHC upgrade to compensate the luminosity loss due to a large crossing angle at the interactions points. In order to be beneficial for luminosity, the crab cavity system must have extremely good RF noise performance, else the emittance blow-up from its own noise may further degrade the luminosity.
Required noise performance of the Low-level RF and High-power RF systems is beyond the limit of what is possible with current technology.
An active "noise feedback" in the LLRF system was therefore proposed to help mitigate the emittance growth from the crab cavity system. We present the challenges of very demanding noise feedback LLRF system design, proposed processing algorithms and preliminary results from the proof of concept testing phase.
The challenge is not only the ultra low noise digitizer with large bandwidth and low ENOB converters, but also implementing a high performance, strictly beam synchronous bunch by bunch measurement into an asynchronous, fixed clock LLRF system.

Speaker: Daniel Valuch (CERN)

53 Development of a Feedback-Based Reference Compensation System for the Beam Monitor at J-PARC LINAC

In the J-PARC LINAC, the beam monitor and LLRF systems utilize independent RF references. The LLRF system operates at 312-MHz and 960-MHz LO frequencies and includes active environmental compensation, whereas the monitor’s 324-MHz RF reference distribution system lacks this capability, leading to humidity-dependent phase drift at downstream stations. To reduce environmental dependency and enhance stability, a feedback-based compensation system based on μTCA.4 technology is implemented. The system performs IF phase correction by down-converting the 324-MHz monitor reference tapped from the SSA output to 12-MHz on μRTM, followed by fast feedback calculations in FPGA, enabling real-time compensation of phase drift. The resulting 324-MHz IQ-modulated output is sent via the μRTM to drive the SSA for distribution to monitor systems in klystron gallery. The developed system is designed to mitigate environmental phase fluctuations to enhance reference stability, improve beam monitoring reliability, and support future beam power upgrades at J-PARC. Moreover, the new system leverages the existing LLRF infrastructure, installed in μTCA.4 crate at MEBT1, allowing a fully synchronized, cost-effective, and compact system, contributing to more sustainable operation. This paper presents design methodology, long-term reference comparison and initial feedback implementation results.

Speaker: Dr Ersin Cicek (High Energy Accelerator Research Organization (KEK))

54 Advanced LLRF Automation and Diagnostic Strategies for Horizontal Testing of HIAF SRF Cavities

The High Intensity heavy-ion Accelerator Facility (HIAF), currently under construction, will employ a series of superconducting RF (SRF) cavities in its injector linac (iLinac) to accelerate heavy-ion beams. Comprehensive performance validation of each SRF cavity in a horizontal test stand prior to its installation in the accelerator tunnel is a critical prerequisite for the successful commissioning of the iLinac. To this end, we have developed an advanced Low-Level RF (LLRF) automation and diagnostic system for the horizontal test stand of HIAF's low-beta SRF cavities. This system integrates several key functions: high-precision measurement of cavity parameters, automated conditioning at both room and cryogenic temperatures, reliable quench detection, and stable closed-loop operation. The successful application of these advanced strategies not only validates that the cavity performance meets design specifications but also significantly enhances the efficiency and consistency of the testing process, laying a solid foundation for the subsequent installation and commissioning of the HIAF iLinac.

Speaker: FENG QIU (Institute of Modern Physics)

Coffee Break

55 Status of the ISIS Digital LLRF Systems

A digital LLRF system [1] has been successfully developed and deployed for control of the accelerating Voltages on the Ferrite loaded RF cavities on the ISIS Synchrotron over the last decade. The final stage of the digital control system has recently been completed which now includes digital control of the cavity tuning.
Similar National Instruments FPGA modules to those used in the Synchrotron LLRF system have been used to develop a LLRF control system for the RAL Front End Test Stand (FETS) [2] and the ISIS Pre-Injector Test Stand (PITS) [3]. These systems are based on the digital LLRF system developed at the University of the Basque Country [4].
The RF system on FETS comprises of a Radiofrequency Quadrupole (RFQ) and 3 re-bunching cavities operating at 324MHz. That for PITS consists of an RFQ and 4 quarter wave resonator cavities all operating at 202.5MHz and is intended as a pre-cursor to the upgrade of the ISIS Pre-Injector planned for 2027, when the same LLRF control system will also be deployed on the 4 LINAC tanks and de-bunching cavity. Initial tests of the LLRF system have been made on one of the QWR cavities and both RFQs and will be continued as more cavities become available.

1. “Status of the ISIS Synchrotron Digital LLRF System” Seville et al,
   LLRF 2022.
2. “Status of the RAL Front End Test Stand” Letchford et
   al, IPAC 2015.
3. “The Pre-Injector Upgrade for the ISIS H− LINAC”
   Lawrie et al, LINAC 2022.
4. “New PXIe-Based LLRF Architecture and Test Bench for Heavy Ion Linear Acceleration” Badillo et al, IEEE-NPSS Real Time Conference 2014

Speaker: Andrew Seville (UKRI)

56 Upgrade of the Barrier Bucket LLRF system for High-Intensity, Low-Loss Multi-Turn Extraction at the CERN PS

The CERN Proton Synchrotron (PS) LLRF system is one of the oldest in operation at CERN. To meet the growing demands of high-intensity fixed-target experiments at CERN, a sophisticated beam manipulation technique combining barrier-bucket radiofrequency gymnastics with Multi-Turn Extraction (MTE) has been developed and successfully implemented in the PS.
The newly developed system enables cycle to cycle updates off the turn-synchronous voltage waveform applied to the wide-band Finemet cavity. It allows both intra-cycle manipulations and synchronization with respect to the Super Proton Synchrotron (SPS) extraction reference. These features have been fully tested with both the MTE and ion beams, successfully demonstrating synchronous barrier bucket extraction and non-integer harmonic batch compression.
This contribution summarizes the upgrades to the Finemet cavity controller, showing the new system architecture and demonstrating its operation with beams in the machine.

Speaker: Toma Gavric (CERN)

Special Topic

12:05 PM Lunch (not provided)

Tutorial: Electromagnetic Compatibility. Does it matter when everything is digital anyway?

Convener: Daniel Valuch (CERN)

57 LLRF Upgrades for Studying Transient Beam-Loading in RHIC 28 MHz Accelerator Cavity for the Electron-Ion Collider

The 28 MHz cavities, currently used in the Relativistic Heavy Ion Collider (RHIC), will be modified into 24.6 MHz cavities to be used in the Hadron Storage Ring (HSR) for the future Electron-Ion Collider (EIC). One major difference between the EIC and the current RHIC system is that the EIC HSR will host proton beams with 10 times shorter bunch length, 3 to 10 shorter bunch spacing, and up to 3 times higher beam current than those in RHIC. While this will allow for greater luminosity, it will also introduce challenges for the LLRF system in the form of stronger transient beam-loading. To counteract these effects, digital implementations of a feedfoward (FFWD) and One-Turn Delay Feedback (OTFB) have been developed for an FPGA. Furthermore, using a newly developed digital network analyzer, software has been created that allows for a straightforward method of tuning the LLRF systems for maximum cavity impedance reduction. These developments will be evaluated with beam in the 28 MHz cavities during the 2025 RHIC Run.

Speaker: Arshdeep Singh (Brookhaven National Laboratory)

Poster Session for Software, SRF Controls, Timing and Synchronization, Measurement and Controls, & Others

Conveners: Arshdeep Singh, Bartosz Gasowski, Bozo Richter, Jayendrika Tiskumara, Jorge Diaz Cruz, Kai Xu, Kemal Shafak, Kenta Futatsukawa, Kiyomi Seiya, Kyle Fahey, Kyungtae Seol, Larry Doolittle, Maciej Urbanski, Michael Brown, Nicholas Ludlow, Paula Van Rooy, Philip Varghese, Rajesh Sreedharan, Samson Mai, Timothy Madden, Volker Ziemann, Xianghe Fang, Xuefang Huang

58 Development of an FPGA-based Cavity Simulator for Testing RF Controls

LLRF is used to precisely control the amplitude and phase of the RF field in cavities. Often times, access to test the control algorithms with RF equipment, especially in the presence of beam, is limited or beyond reach. In such cases, testing must be done through computer modeling or simulations. Computer modeling is often too slow and difficult to interface with the LLRF hardware. Analog or digital cavity simulators are preferred as they allow for interaction with the LLRF controls platform in real-time, and compared to their analog counterparts, FPGA-based digital cavity simulators allow for a more adjustable and sophisticated implementation. The newly developed FPGA-based cavity simulator includes the cavity electrical model, the cavity mechanical model including Lorentz Force Detuning and microphonics, an amplifier model which can simulate real amplifier nonlinearities, and a beam model. The simulator will be validated using measurements from BNL’s CeC 500 MHz NCRF cavity and the CeC 704 MHz 5-cell SRF cryomodule.

Speaker: Arshdeep Singh (Brookhaven National Laboratory)

59 A Phase-Stable, Low-Loss, High-Directivity 162.5 MHz Coupler for Use in a Phase Reference Distribution Line

We present a custom-designed directional coupler intended for use in phase reference distribution systems for linear particle accelerators. Such systems require low phase drift, handle relatively high-power signals, and often are subjected to ionising radiation. The coupler is designed for an operating frequency of 162.5 MHz, 25 dB coupling, and input power in the range of 40-50 dBm. The prototype achieves mainline insertion loss below 0.03 dB and directivity above 35 dB. Its physical length of 21 cm (approx. 8¼") is well below quarter-wavelength, making it relatively compact. To allow use of the coupler near the beam-line, radiation-sensitive materials such as PTFE are avoided in the construction. The internal structure is realized on a printed circuit board (PCB), which allows for ease and high repeatability of manufacturing. Importantly, the PCB dielectric serves mainly as a mechanical support for the copper pattern and its influence on the electromagnetic field is minimized. This helps reduce phase drifts due to the sensitivity of dielectric permitivity to temperature changes.

Speaker: Bartosz Gąsowski (Warsaw University of Technology)

60 Resonant filling for long pulse operation of EuXFEL using iterative learning based feed forward

A future operation scenario of the European XFEL (EuXFEL) is long pulse (LP) mode, where the 800 superconducting radio frequency (SRF) cavities of the linac are energized with RF pulse lengths of up to 500ms, in contrast to the current short pulse (SP) mode with only 1.4ms. To improve energy efficiency of LP operation, cavities must be operated at bandwidths in the range of tens of Hertz, narrower by a factor of 10 than in SP. Due to peak power limitation of the proposed high power amplifiers, the fill time will extend to several milliseconds, surpassing the period of mechanical resonances of TESLA cavities. To ensure RF filling on resonance, Lorenz force detuning induced cavity phase shifts are tracked by employing iterative learning control (ILC) on the incident RF phase in a single cavity regulation setup. In vector-sum RF regulation systems, the incident phase cannot be adjusted to each cavity individually. Hence, the concept is inverted by employing ILC on mechanical cavity tuners to align each individual cavity resonance with the common RF drive. Both approaches are simulated and evaluated experimentally.

Speaker: Bozo Richter (Deutsches Elektronen-Synchrotron DESY)

61 Identifying the source of beam loss events with Fast Data Acquisition (DAQ) Chassis

Determining whether an RF cavity with an undetected gradient or phase transient is the culprit behind a beam loss event has been found to be a valuable tool for CEBAF operations. Analysis of beam position with the existing switched electrode electronics BPM hardware at the dispersive area and energy variation before a beam loss event was suggested as a method to determine if the beam loss event was correlated with an energy transient. With this purpose in mind, a prototype off-line system was developed in the fall of 2022. It implemented using National Instruments hardware and LabVIEW software and relied on a software trigger and was not integrated into the EPICS control system. Beam trips with energy transients are compared to the reason for the trips found in the CEBAF down time monitoring system. The initial results indicated that 20% of the faults had energy transients that were not coincident with any cavity faults. As a result cavity interlocks were adjusted so that the cavities tripped on such events. As a solution an existing data acquisition system that was developed for monitoring legacy RF systems in CEBAF system was deployed. It was used to capture BPM wire signals at a sample rate of 20 ksps; was triggered by a fiber signal that is part of the fast shutdown system; and was integrated into the EPICS control system. In addition to being able to analyze the energy transients live in the control room as well as after the fact, these systems allowed us to understand the energy jitter properties just prior to the fault. This paper will present recent results and describe a path forward using commercial off the shelf hardware installed in multiple locations which can be easily be integrated into EPICS.

Speaker: Jayendrika Tiskumara (Jefferson Lab)

62 LEMP LLRF Firmware and Software

The LCLS began operations in 2009, utilizing SLAC's normal-conducting LINAC, which features control equipment dating back to the 1960s and 1980s. The Linac Electronics Modernization Plan (LEMP) aims to replace the legacy control equipment with a system based on the open-source Marble carrier board and a modified version of the Zest digitizer board, both of which are used in the LCLS-II HE LLRF system. Adaptation of the LLRF system from the CW SRF LCLS-II to the short RF pulse NC LCLS includes leveraging the knowledge and experience gained from recent LLRF projects at SLAC and efficiently reusing the core functionality of the code base developed at LBNL. Here, we describe the firmware and software infrastructure, highlight key features, and present initial test results.

Speaker: Jorge Diaz Cruz (SLAC)

63 Integrated Automation in SHINE LLRF Control System: Design, Implementation and Performance

This paper presents the design, implementation, and operational performance of the Low-Level Radio Frequency (LLRF) control system for SHINE. The system adopts a two-layer software architecture to achieve integrated automation in RF field stabilization, fault handling, and multi-cavity coordination. The lower layer utilizes EPICS IOCs implemented on Zynq SoC platforms to provide real-time cavity control. This layer supports multiple operational modes including normal beam operation, maintenance procedures, and automatic fault recovery.The upper management layer coordinates all cavities through distributed EPICS PV monitoring and implements system-wide fault tolerance logic. Key features include real-time status monitoring, automated fault analysis, and coordinated recovery. Notable innovations include the EPICS-Zynq integration for low-latency control, dynamic reconfiguration capability for different operation modes, and data-driven fault diagnosis.This control architecture represents a significant advancement in accelerator automation, combining real-time hardware control with intelligent system management. The implementation provides a robust solution for SHINE's demanding performance requirements while offering tools for efficient operation and maintenance.

Speaker: Mr kai xu (Shanghai Advanced Research Institute, CAS)

64 Few-Femtosecond Synchronization of Independent Beamlines in High-Power Laser Facilities via a Fully-Automated Fiber-Optic Timing System

We present a fully automated fiber-optic timing distribution and synchronization system developed for high-power laser facilities that require few-femtosecond synchronization between multiple beamlines, each equipped with an independent seed oscillator.
Building on our previous work in pulsed-optical timing distribution using femtosecond lasers and ultra-low-noise stabilized fiber links*, the system achieves an out-of-loop timing drift of just 5.2 fs RMS over 10 hours between a Ti:Sa laser at 780 nm and a Yb laser at 1030 nm, synchronized remotely via fiber-optic links.
The system includes out-of-loop optical delay lines, integrated into the master platform and a coaxial RF distribution subsystem operating in parallel to the fiber-optic links. This allows high-precision, full pulse-period delay tuning of 13 ns, enabling deterministic phase bucket selection across all synchronized beamlines.
An automatic re-locking mechanism restores pulse alignment across all beamlines after oscillator restart without user intervention. The system integrates natively with EPICS control environments and supports robust 24/7 operation, enabling reproducible, high-precision pump–probe experiments.

Speaker: Dr Kemal Shafak (Cycle GmbH)

65 Study of a Relative Phase Drift Monitoring System Inferred from Beam Loading at J-PARC LINAC

At the J-PARC LINAC, the RF sources and monitoring systems have historically utilized different reference frequencies and its distribution system. As a result, it has been difficult to directly compare the phase of the beam, measured via monitoring systems, with the cavity pickup RF signals. Meanwhile, the phase drift caused by environmental factors such as temperature and humidity has become a significant issue, as it strongly affects the output momentum. This has highlighted the need for a system that can monitor the relative phase between the beam and the RF. However, the development of new monitors and readout devices is difficult due to budget constraints. To address this, we have investigated a method to monitor the phase drift by estimating beam loading inferred on the difference in the input RF waveforms to the cavity with and without beam. While the absolute value of the relative phase cannot be trusted due to uncertainties in the directional coupler and cavity parameters, the phase variation can be reliably used for monitoring purposes. In this paper, we present the advantages of this monitoring approach based on beam test results and analysis of archived data.

Speaker: Kenta Futatsukawa (High Energy Accelerator Research Organization (KEK))

66 Analysis of Required Anode Current in High-Intensity Proton Operations Using LLRF signals and Phasor diagram

The J-PARC Main Ring (MR) is progressing toward the delivery of a 1.3 MW proton beam to the Hyper-Kamiokande neutrino experiment by 2028. To achieve this, the number of protons per pulse (ppp) will increase from 2.3E14 to3.1E14 ppp along with a reduction in the repetition cycle from 1.32 s to 1.16 s.

To accommodate the resulting increase in beam loading, the required anode current—supplying power to two 600 kW tetrode vacuum tubes—will approach the maximum rated capacity of 127 A, based on the current cavity configuration and voltage pattern. The generator current from the RF amplifier sustains the cavity gap voltage, which corresponds to the vector sum of the beam-induced current and the generator current.

The digital Low-Level RF (LLRF) control system, implemented in 2019, ensures stability of both the cavity voltage and phase via active feedback control. Key signals such as the LLRF driving RF signal, the gap voltage signal, and the beam signal provide insights into the dynamic behavior of the system.

In this presentation, we will present measurements of these three RF signals and illustrate their interrelationship using a phasor diagram. We will also discuss potential modifications to the LLRF control system to enable integrated real-time analysis based on this measurement approach.

Speaker: Kiyomi Seiya (KEK/J-PARC)

67 Transitioning to EPICS at EIC: PSCDrv

Brookhaven National Lab's Electron-Ion Collider (EIC) plans to migrate from the Accelerator Device Object (ADO) framework developed for Relativistic Heavy Ion Collider (RHIC) applications to the Experimental Physics and Industrial Control System (EPICS) framework. EIC is based on a Common Platform architecture with custom-built hardware for controls and communication between a variety of accelerator component sub-systems: RF, Beam Instrumentation, Power Supplies, Timing, etc. The Common Platform design facilitates communication between carriers, specialized daughter cards, and the EIC global control system. To develop and validate this communication plan, LLRF group is using a specialized packet protocol to send and receive data between a Common Platform carrier and a dedicated EPICS Input-Output Controller (IOC) server.

Speaker: Kyle Fahey (Brookhaven National Lab)

68 RF Phase Reference Distribution System for RAON Heavy-ion Accelerator

The heavy-ion accelerator of the Institute for Rare Isotope Science (IRIS) has been developed and beam commissioning for the low energy superconducting linear accelerator has been performed. There are three types of SRF cavity, which are 81.25 MHz quarterwave resonator (QWR), 162.5 MHz half-wave resonator (HWR), 325 MHz single-spoke resonator (SSR). There are 22 QWRs and 102 HWRs in the low-energy superconducting linac (SCL3), and 69 SSR1s and 144 SSR2s in the high-energy superconducting linac (SCL2). The RF reference distribution system must deliver a phase reference signals to all low-level RF (LLRF) systems and BPM systems with low phase noise and low phase drift. The frequencies of RISP linac are 81.25MHz, 162.5MHz and 325MHz, and there are 130 LLRF systems and 60 BPMs respectively for SCL3, and 240 LLRF systems and 70 BPMs for SCL2. 81.25 MHz signal is chosen to the reference frequency, and 1-5/8“rigid coaxial line is installed with temperature control. This paper describes the design, test results and operation during the beam commissioning of the low-energy superconducting linac.

Speaker: Kyungtae Seol (IRIS / IBS)

69 Obvious and non-obvious aspects of digital Self-Excited-Loops for SRF cavity control

In 1978, Delayen showed how Self-Excited Loops (SEL) can be used to great advantage for controlling narrow-band SRF cavities. Its key capability is establishing closed-loop amplitude control early in the setup process, stabilizing Lorentz forces to allow cavity tuning and phase loop setup in a stable environment.
As people around the world implement this basic idea with modern FPGA DSP technology, multiple variations and operational scenarios creep in that have both obvious and non-obvious ramifications for latency, feedback stability, and resiliency.
This paper will review the key properties of a Delayen-style SEL when set up for open-loop, amplitude stabilized, and phase-stabilized modes. Then the original analog circuit will be compared and contrasted with the known variations of digital CORDIC-based implementations.

Speaker: Larry Doolittle (LBNL)

70 Phase drift Performance of Coaxial Cables for Phase Reference Distribution Systems

Phase reference distribution systems (PRDS) provide highly stable, in terms of amplitude and phase stability, reference signals for every part of particle accelerator control systems, and therefore, are crucial for meeting the beam parameters requirements. Among many PRDS requirements, short and long-term phase stability is paramount. In a brief description, the sources of phase instabilities in PRDS are of short-term character, mainly the phase noise of the RF reference signal source, and long-term character, coming from the phase drift introduced by the long coaxial cables, exposed to environmental factors, like temperature, humidity, and air pressure changes. The contribution presents the recent results of long-term phase drift introduced by some coaxial cables selected for potential use in various parts of LLRF and PRDS systems. The goal is to choose RF cables that, in terms of electrical delay, remain as stable as possible in changing environmental conditions. The results present trade-offs between cable diameter, mechanical flexibility, and phase stability versus temperature change vulnerability.

Speaker: Mr Maciej Urbański (Warsaw University of Technology)

71 The RF Test of the FPGA Based Digital Low-Level RF Control System for the LANSCE Proton Storage Ring

As part of the modernization of the Los Alamos Neutron Science Center (LANSCE), a digital low level RF (LLRF) control system for the LANSCE proton storage ring (PSR) is designed. The LLRF control system is implemented in a Field Programmable Gate Array (FPGA). The high resolution tunable 2.8MHz reference RF is generated by a direct digital synthesizer at the LANSCE front end and is transmitted to the PSR control system located half mile away. Since the digital LLRF control system is synthesized in the In-phase/Quadrature coordinate, the I/Q reference RF signals are generated by the FIR filter based Hilbert Transformer (HT). For the stabilization of the cavity field, a Proportional-Integral (PI) feedback controller is implemented. In addition, for the future application, a Proportional-Derivative (PD) type beam feedforward controller is provided. The performance of the designed LLRF control system was tested on the LANSCE PSR at full RF power without beam operation

Speaker: Dr Michael Brown (LANL)

72 LCLS-II-HE PHASE REFERENCE LINE

The Phase Reference Line (PRL) for LCLS-II-HE is an extension of the PRL used for LCLS-II. The system provides a reference signal of 1300 MHz, a 185.7 MHz reference signal for the timing system, and a 1320 MHz LO for the LLRF system. The 1300 MHz signal is sent along a rigid coaxial cable down in the linac tunnel for minimal changes in length due to thermal expansion and contraction. To cancel out the effect of thermal drift on the phase of the signal, phase averaging is used. For the HE installation, the rigid coaxial line in the linac tunnel will be extended from sector 7 to sector 10. In the klystron gallery, the 185.7 MHz timing reference signal and the 1320 MHz LO signal will be extended down to sector 10 and distributed to the LLRF racks. There is also consideration for moving the MO from sector 2 to the Injector CID for increased beam stability or moving the MO to sector 10 and replacing the RF over fiber system with a coaxial line to the experiment hall for increased stability on that end.
This poster will discuss the overall system design, the performance, the extension of the system for the HE installation and the potential changes made to the existing system.

Speaker: Nicholas Ludlow (SLAC National Accelerator Laboratory)

73 Development of the FPGA Based Digital Low-Level RF Control System for the LANL RFQ Teststand

The LANSCE Modernization Project (LAMP) is evaluating necessary upgrades to enable continuous LANSCE operations in years to come and, as a part of LAMP, the H+ and H- 750-kV Cockcroft-Walton (CW) generators will be replaced with a dual-beam, 3-MeV Radiofrequency Quadrupole (RFQ). For technology maturation and expertise associated with this concept, an RFQ test stand with LAMP-like layout is being set-up to demonstrate dual-beam operation in an RFQ with all beam patterns required by the facility. The RFQ test stand will have 35-keV H+ and H- beamlines that are simultaneously injected into a 750-keV RFQ. In order to stabilize the cavity field, a digital low level RF (LLRF) control system is designed and implemented on a Field Programmable Gate Array (FPGA). For the stabilization of the cavity field, a Proportional-Integral (PI) feedback controller is implemented. For the beam loading compensation, a beam emulator is implemented on the digital LLRF control system, where the profile of the beam signal, beam loading time, beam ramp time, beam pulse length, are set to be programmable. The beam emulator output is used for the Proportional-Derivative(PD) type digital beam feedforward controller.

Speaker: Paula Van Rooy (LANL)

74 Update on PIP-II beam pattern generator upgrade

The beam pattern generator enables the transfer of beam pulses from the PIP-II linac to the Booster ring, the two RF systems being non-harmonically related. It is synchronized to the timing system to provide beam arrival information to the downstream accelerator subsystems. The design is being upgraded with COTS components and is being developed with a collaboration with SLAC.The pattern generation, digital signal processing and the user interface to an external EPICS server are integrated onto the ARM processor of the SOCFPGA. The progress of the system development is described.

Speaker: Dr Philip Varghese (Fermilab)

75 Status of DLLRF System Development for Soleil-II Project

A compact digital Low Level Radio Frequency (LLRF) system, based on the MicroTCA plateform, is being developed for the SOLEIL upgrade project towards SOLEIL II. This system will provide better flexibility and easier maintenance than the present analog one. Working with a 10 MHz intermediate frequency (IF) and a UltraScale+ Zynq board makes it easily adaptable to any other RF system.

Speaker: Mr Rajesh SREEDHARAN (Synchrotron SOLEIL)

76 Baseband Digital Network Analyzer Upgrade for LLRF Controllers

Digital Network Analyzers (DNA) have been implemented in many LLRF systems to help characterize and tune digital feedback loops. A modular DNA has been developed on FPGA and integrated into the current RHIC LLRF infrastructure. The DNA characterizes a system by injecting a complex baseband chirp to calculate the system’s magnitude and phase response. The DNA is also able to measure the open loop gain, gain and phase margins, and loop delay to help fine tune feedback loop parameters. The DNA has been verified with an implementation of one-turn delay feedback (OTFB) on the bench to maximize gain and stability. The DNA and OTFB are planned to be evaluated with dedicated beam time during a RHIC Accelerator Physics Experiment (APEX) study of transient beam loading. Once verified, the DNA will be integrated into the Common Hardware Platform for the future Electron-Ion Collider (EIC).

Speaker: Samson Mai (Brookhaven National Laboratory)

77 RF Data Acquisition System for the APS Upgrade

An FPGA- and software - based system has been developed for real-time data acquisition (DAQ) on numerous RF and other technical subsystems of the Advanced Photon Source (APS) accelerator. The software, called DAQ, is based upon the EPICS control system and is tightly integrated to FPGA hardware running on a Micro Telecommunications Architecture (TCA) platform. The FPGA hardware continuously streams data from RF systems over a Peripheral Component Interconnect Express (PCIe) bus as Direct Memory Access (DMA) transfers to a Micro-TCA- based Linux blade. DMA data transfers trigger the EPICS DAQ software running on the Linux blade to continuously stream data to the APS network using the EPICS 7 PVAccess protocol. The RF DAQ software is integrated with many distributed software services on the APS network including data storage, data visualization, and RF system monitor and control. Development of this system required the integration of FPGA firmware, electronics hardware, and software developed by multiple groups at multiple institutions.

Speaker: Timothy Madden (Argonne National Laboratory)

78 System identifications of superconducting cavity parameters with recursive least squares algorithms

Based on analyzing the forward and transmitted signals we describe
algorithms to continuously improve estimates of cavity parameters,
such as bandwidth and detuning. We also discuss the trade-off between
ultimately achievable precision and the ability to follow time-varying
parameters. The method can be adapted to additionally measure the
unloaded and the external quality factor.

Speaker: Volker Ziemann (Thomas Jefferson National Accelerator Facility)

79 Measurement and Performance Analysis of the Upgraded Intra-Pulse Feedback Loop for the S-Band Power Station at SPARC_LAB

With the EuPRAXIA@SPARC_LAB launched at LNF-INFN as scheduled, the LLRF systems at SPARC_LAB are undergoing some major upgrades to support the cutting-edge research of plasma wakefield accelerations. The demanding requirements for RF stability of particle-driven plasma wakefield acceleration are on the edge of the state of the art, which imposes a big challenge to the synchronization of the RF subsystems. The S-band power station currently in operation contributes to the most RF phase jitters to the facility, because of the nature of the PFN modulators. One feasible solution to tackle this problem is a fast phase feedback loop to stabilize the phase. To evaluate and analyze this feedback system, two sets of measurements were carried out. First, a long-term test was performed using the existing loop, confirming its ability to operate stably over 8 hours without intervention. Subsequently, an upgraded version of the loop was developed, adding features such as remote gain control and addressing known limitations of the original design. Short-term measurements were carried out to test these enhancements. The upgraded system demonstrated stable and precise gain control, and the phase jitter was successfully reduced to 15 fs RMS. This marks a notable improvement over the original setup and makes a meaningful step toward meeting the strict RF stability requirements of advanced plasma accelerators.

Speaker: Xianghe Fang (INFN-LNF)

80 LLRF Control System for S-Band Deflecting Cavity at SHINE

A traveling-wave transverse RF deflecting structure enables bunch length measurements at the Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE). To enhance amplitude and phase stability in this S-band cavity, an efficient LLRF control system implements pulse-to-pulse techniques: feedforward control dynamically adjusts intra-pulse modulator HV amplitude to regulate klystron output power (accelerating voltage), while feedback control stabilizes phase by adapting the low-level RF drive. This paper presents the system's detailed design and implementation.

Speaker: xuefang huang

Timing and Synchronization Block

81 Upgrade of BEPC-II LLRF and synchronization system for the new PWFA research

BEPC-II(Beijing Electron Positron Collider) has been upgraded in past three years both on LLRF system and synchronization system. A new PWFA(Plasma Wake-Field Acceleration) test facility is built to verify electron and position collider based on PWFA principle including the world-first positron acceleration and world-first cascaded-stage acceleration. So this PWFA beam should be synchronized with beam from BEPC-II, new lasers, new phase reference line and LLRF has been built or upgraded. The status of PWFA experiment related with LLRF will be talked.

Speaker: Dr Xinpeng Ma (IHEP)

82 Master Oscillator and Phase Reference Line Design for the PIP-II Linac

The phase averaging reference line system provides the RF phase reference , LO and clock signals to the LLRF and other accelerator subsystems. The PIP-II linac has RF systems at three frequencies – 162.5 MHz, 325 MHz and 650 MHz. A temperature-stabilized, low-phase-noise oscillator is used as the master oscillator. Phase reference signals at 162.5 MHz, 325 MHz, and 650 MHz, along with LO signals at 182.5 MHz, 345 MHz, 670 MHz and LLRF clocks at 1320 MHz and 1300 MHz, are generated in temperature-controlled RF modules at each frequency section. A phase reference from each module travels to the next section, where it is doubled to produce required frequencies. The reference also travels alongside the accelerating cavities in the tunnel, allowing cavity probe and reference cables to temperature track and reduce measurement errors from temperature changes or phase drift. The design of the the reference line is described here.

Speaker: Ahmed Syed (Fermilab)

Hardware Block 1

83 RFSoC-Base LLRF Development for CSNS-II LINAC

​​RFSOC (Radio Frequency System-on-Chip) integrates FPGA, ARM processors, RF analog-to-digital converters (ADCs), and RF digital-to-analog converters (DACs) onto a single chip, representing a third-generation leap in hardware technology following the shift from analog to digital circuits.​​ Applying RFSOC to accelerator systems ​​significantly enhances operational efficiency while substantially reducing development complexity, hardware maintenance burden, and overall cost.​​ This report ​​will survey​​ recent progress in utilizing RFSOC for accelerator applications, ​​analyze​​ relevant performance metrics, and ​​present​​ research and implementation work concerning RFSOC in the Low-Level RF (LFB) system of the China Spallation Neutron Source (CSNS) linear accelerator.

Speaker: Zhexin Xie (ihep/csns)

84 RFSoC based LLRF system design at ALS

The Advanced Light Source (ALS) at LBNL is upgrading several LLRF systems for its Linac and Sub-Harmonic Bunchers, where it is desired to have a unified LLRF system design to support various RF frequencies (at 125MHz, 500MHz and 3GHz) and configurations. This paper demonstrates an open-source, direct sampling RFSoC based LLRF system design, featuring: sample-to-sample Multi-Tile Synchronization, deterministic latency, digital up/down conversion, arbitrary waveform generation and acquisition, in-pulse closed loop control, timing and EPICS integration, modular RF frontend and hardware designs. Measured RF characteristics show that the RFSoC LLRF system is able to meet the system requirement.

Speaker: Qiang Du (Lawrence Berkeley National Laboratory)

85 A high-speed MTCA.4-based digitizer for the LLRF control system of the J-PARC MR

The J-PARC Main Ring (MR) is a high-intensity proton synchrotron that accelerates protons from 3 GeV to 30 GeV.
Its output beam power for fast extraction reached 830 kW, corresponding to 2.37 × 10$^{14}$ protons per pulse in March 2025.
Coupled bunch oscillation is well suppressed with the newly installed LLRF control system for the MR.
Instead of the coupled bunch instability, longitudinal microwave instability is observed in the later part of the acceleration.
A new high-speed digitizer is introduced into the LLRF system to monitor the microwave instability.
In this presentation, we present the configuration of the digitizer and its preliminary status.

Speaker: Yasuyuki Sugiyama (KEK/J-PARC)

Workshop Dinner

Thu, October 16

Breakfast at your leisure (not provided)

Shuttle to Jefferson Lab, Information Table and Luggage Room Open

Welcome & LOC Announcements

86 Low-Level RF System Development for EIC Crab Cavities

The Electron-Ion Collider (EIC) will operate with a 25 mrad crossing angle at the interaction points to enable rapid beam separation, reduce detrimental beam-beam effects, and provide space for forward detectors. This crossing geometry, however, significantly reduces the overlap region of the colliding bunches, resulting in nearly an order of magnitude luminosity loss. To restore effective head-on collisions and achieve maximum luminosity, crab cavities will apply transverse kicks to each bunch, rotating them in the crossing plane. The success of this scheme depends critically on the performance of the Low-Level RF (LLRF) system, which must deliver high-gain, low-noise field control to suppress transverse emittance growth and maintain beam stability. This presentation will describe the LLRF system architecture and control strategy for the EIC crab cavities, including RF noise mitigation, impedance control, crabbing phase closure, and integration planning. The current hardware development status and the roadmap toward full system implementation will also be presented.

Speaker: Mr Freddy Severino (Brookhaven National Labs)

Measurement and Controls Block 3 & Hardware Block 2

87 Development and Testing of a Low-Noise X-Band LLRF Prototype System

Low-Level RF (LLRF) systems are fundamental to the precise control of accelerating fields in modern particle accelerators, ensuring the required stability in amplitude and phase to achieve consistent beam quality. As accelerator technologies evolve toward higher frequencies and more compact designs, the X-band regime is increasingly adopted due to its support for high-gradient structures and ultra-short RF pulses. However, the shift to X-band introduces greater sensitivity to phase noise, timing jitter, and thermal fluctuations, requiring a new generation of LLRF controllers with faster signal processing and tighter control loops. In this context, a dedicated X-band LLRF prototype has been developed to meet the demanding requirements of the future EuPRAXIA@SPARC_LAB LINAC, as part of the EuPRAXIA Doctoral Network. The prototype integrates a high-speed front-end and back-end system optimized for fast pulse processing and enhanced signal fidelity. It is now prepared for full evaluation on a real accelerator test bench at the TEX facility, INFN-LNF. This paper presents the concept, implementation, and readiness of the prototype system.

Speaker: Mr Phani Deep Meruga (Instrumentation Technologies)

Round Table

Coffee Break

88 Analysis of Deployment Challenges for Machine Learning Signal Processing Algorithms

A challenge that industrial particle accelerators face is the high amounts of noise in sensor readings. This noise obscures essential beam diagnostic and operation data, limiting the amount of information that is relayed to machine operators and beam instrumentation engineers. Machine learning-based techniques have shown great promise in isolating noise patterns while preserving high-fidelity signals, enabling more accurate diagnostics and performance tuning. Our work focuses on investigating the challenges associated with the implementation of a noise reduction autoencoder that operates in real time on a Field Programmable Gate Array, which we do by creating firmware to run on a Xilinx ZCU104 evaluation kit with the intention of being deployed on industrial particle accelerators in the near future.

Speaker: Jonathan Edelen (RadiaSoft)

Education Panel (TBA)

Closing Remarks and SPC Updates

Group Photo

12:05 PM Lunch (not provided)

JLAB Tour