Six-Month Follow-Up on Action Items of Feb 2016 CEBAF Field Emitter Workshop

Monday Sep 12, 2016, 12:25 PM → 3:30 PM US/Eastern

TL1227 (Test Lab)

Arne Freyberger (JLAB-Accelerator Division-Operations Department), Geoff Krafft (JLab), Rong-Li Geng (Thomas Jefferson National Accelerator Facility)

It has been about six months since the February 29 mini-workshop on field emitter particulates in CEBAF beamlines. Progresses have been made or are being made in several fronts related to the action items, all aligned with the goal of understanding and reduce field emission in CEBAF. A six-month follow-up is deemed conducive to the final goal of reversing the "lost gradient" in CEBAF. Toward that end, a special PIT meting is to be conducted on September 12, 2016 to allow capturing and measuring the initial results of all efforts related to the action items. Please keep your presentation succinct. If you have any questions regarding your presentation, please ask Rongli. You can find references to the February 29, 2016 Mini-Workshop on Beam Line Field Emitter Particulate in CEBAF SRF Linacs at this web link: https://www.jlab.org/indico/event/139/

1:25 PM → 1:30 PM Introduction

Speaker: Dr Rong-Li Geng (Thomas Jefferson National Accelerator Facility)

Slides Introduction_talk_RG_12sep16.pptx

1:30 PM → 1:35 PM Field emission onset data from present C50 module C50-12 CMTF testing and comparison against prior C50 modules (1-11)

Speaker: Mr Michael Drury (Jefferson :Lab)

Slides Field_Emission_Onset_for_C50_Cryomodules_acceptance.pptx

1:35 PM → 1:40 PM Field Emission onset data from VTA testing of C50-12 cavity pairs as compared to prior C50 cavities pairs

Speaker: Liang Zhao (JLab/W&M)

Slides Field_emission_onset_data_from_VTA_testing_of_C50_pairs_20160912.pptx

1:40 PM → 1:50 PM Improved procedure and practice in C50-12 cavity string assembly as compared to prior C50 strings

Speaker: Danny Forehand (JLAB)

Slides C50_Cavity_pair_Assembly_Changes.pptx

1:50 PM → 2:00 PM Improved procedure and practice in C50-12 cryomodule assembly as compared to prior C50 cryomodules with a special attention to the step of supply-end-can side UHV manifold attachment

Speakers: Frank Humphries (JLAB), Gianluigi Ciovati (JLab), John Fischer (JLAB)

document C50-12_particle_counts.xlsx Improved_procedure_and_practice_in_C50.docx

pictures C50-12_NEG__ion_pump.JPG

2:00 PM → 2:05 PM Gas load desorbed from room temperature warming up of cryomodules and rationale for next generation beamline vacuum system

Speaker: Dr Rong-Li Geng (Thomas Jefferson National Accelerator Facility)

Slides Gas_load_desorbed_from_room_temperature_warming_up.pptx outgassing_1L12.pptx

2:05 PM → 2:15 PM NEG pump for C50-12 and initial experience

Speakers: Kurt Macha (JLAB), Dr Marcy Stutzman (Jefferson Lab)

Slides NEG_materials_and_effective_speeds.pptx

2:15 PM → 2:25 PM Off-line evaluation of NEG pump by integrated vertical testing a single-cell cavity

Speaker: Gianluigi Ciovati (JLab)

Slides RF_test_results_SRF_cavity_NEG_pump.pptx

2:25 PM → 2:30 PM Hi-potting halted or not? Evidence of benefit?

Speaker: Arne Freyberger (JLAB-Accelerator Division-Operations Department)

Slides Hipot.pdf

2:30 PM → 2:50 PM Design and implementation of a new clean room environment for tunnel work and first use for NL12 warm girders and next steps for improvements

Speaker: Mr John Heckman (JSA)

Slides Design_and_Implementation_of_New_Cleanroom_for_Tunnel.pptx

2:50 PM → 3:00 PM First experience of “particulate free” warm girder NL12 & NL13 assembly with real-time particulate monitoring and identified improvements for next round of practice

Speakers: Chris Dreyfuss (JLAB), Danny Forehand (JLAB), Greg Marble (JLAB)

Slides NL12_Girder_Removal_and_Reinstallation.pptx

3:00 PM → 3:05 PM Design and first use of the slow venting apparatus for NL12 warm girders and future improvements

Speakers: Dr Ari Palczewski (Jefferson Lab), Danny Forehand (JLAB)

Slides tunnel_slow_bleedup_and_pumpdown.pptx

3:05 PM → 3:25 PM Particulates collected and analyzed from UHV surfaces of NL12 and NL13 warm girder components

Speakers: Dr Anne-Marie Valente-Feliciano (Jefferson Lab), Charles Reece (JLab), Mr Joshua Spradlin (Jefferson Lab)

Slides Girder_Particulate_Summary_1_-_2016-09-11a.pdf

3:25 PM → 3:30 PM Post-mortem investigation of leaky gate valves (warm gate valves and cold valves): condition of Viton O-ring in terms of particulate shedding and nature of failure

Speakers: Greg Marble (JLAB), Dr Rong-Li Geng (Thomas Jefferson National Accelerator Facility)

Slides leaky_gate_valve_post_mortem.pptx