Speaker
Description
In 1998 when planning for the 12 GeV upgrade got underway, the maximum beam power was specified as 960 kW, consistent with the original 1 MW limit. While the Environmental Assessment (EA) conducted in 2007 allowed 1 MW each to Halls A and C, the 12 GeV upgrade project kept the original power limit specification. The C100 cavities were designed with high input impedance, emphasizing gradient over current capability ($P=V^2/R + I^2R$). The C75 cavity was designed to the same specification in 2017. Both types are limited to about 450 μA summed over all passes and Halls. The EA of 2007 gives an opportunity to consider doubling the beam power. In this talk the limitations and possibilities of various systems are discussed. The intermediate heat exchanger in the shared beam dump cooling system is specified at 1.1 MW. The JLab Facilities organization is beginning planning for
heat exchanger upgrade. All JLab safety documentation specifies 1 MW maximum and the changes in the documentation to match the 2007 EA are expected by year-end. Eight stub tuners which may be used to alter the C100 cavity impedance seen by the RF source are on order and will be installed this spring. Beam tests to determine the highest power than can be delivered with the system as it exists are planned by year-end. If the stub tuners are successful they will be installed on all C100 cavities as funding permits. It is hoped that by mid-decade it will be possible to deliver 70 μA fifth pass simultaneously to Halls A and C, total beam power ~1.6 MW. Hall A and C beam dumps are rated at 1 MW each. Hall D beam dump is rated at 100 kW. Hall B will soon install a 100 kW dump. These power limits will remain even if beam energy is increased. The A and C beam dumps have been evaluated to 16 GeV; all four will have to be re-evaluated if energy is increased beyond that.
