TUOZGD3
SLAC, Menlo Park, California, USA
UCSF, San Francisco, California, USA
Northwestern University, Northwester Medicine Proton Center, Warrenville, Illinois, USA
LLU, Loma Linda, USA
We report on the development of a 2.856 GHz accelerator system to provide energy modulation and RF-based steering for rapid 3-D beam scanning for proton therapy. Designs for the accelerator and deflector cavities have been modeled in ANSYS-HFSS and used to produce prototype structures. We present high power test results for a single cell energy modulator prototype and a three cell deflector prototype. Using General Particle Tracer, we simulate proton beam transport through the fully rendered accelerator and deflector beamline. System performance is optimized for the case of sub-relativistic protons with 230 MeV kinetic energy and covers an energy modulation range of ±30 MeV. We present simulated beam profile data after energy modulation and lateral steering, achieved using a combination of dynamic RF deflector cavities and static permanent magnet quadrupoles.
LANL, Los Alamos, New Mexico, USA
Michigan State University, East Lansing, Michigan, USA
SLAC, Menlo Park, California, USA
MSU, East Lansing, Michigan, USA
This work presents the results of high gradient testing of the two C-band (5.712 GHz) normal conducting ß=0.5 accelerating cavities. The first cavity was made of copper and second was made of copper-silver alloy with 0.08% silver concentration. The tests were conducted at the C-Band Engineering Research Facility of New Mexico (CERF-NM) located at Los Alamos National Laboratory Both cavities achieved gradients in excess of 200 MV/m and surface electric fields in excess of 300 MV/m. The breakdown rates were mapped as functions of the gradient and peak surface fields. The gradients and peak surface fields observed in the copper-silver cavity were about 20% higher than those in the pure copper cavity with the same breakdown rate. It was concluded that the dominant breakdown mechanism in these cavities was not the pulse heating but the breakdown due to very high surface electric fields.