Analysis and modelling of improved accelerating cavities for the recirculating linear accelerator (RLA)

Concerns about energy spreads due to degradation of 1.1 MV, 34 ns duration accelerating cavity repeating pulse shapes have resulted in improving the 24-switch trigger system for the ET-2 cavity, and identifying critical factors in the cavity design that affect the pulse shape. The authors summarize the improvements (completed and proposed) for the existing ET-2 cavity and the status of the design analysis and modeling of accelerating cavities. A relativistic electron beam (REB) injector for the RLA is being installed which will provide a higher amplitude (~4 MV), longer duration (~40 ns FWHM), more rectangularly shaped (~25 ns full width at 90% peak) waveform and a colder beam than were achievable with the previous 1.5 MV injector. The constant beam energy can be more efficiently matched to the guiding IFR plasma channel in the beam line and to the turning section magnetic fields. The accelerating cavities are being designed to produce more compatible accelerating voltage pulses in terms of waveform flatness, width, and amplitudes