Drive linac for the Argonne Wakefield Accelerator

The drive linac in Phase I of the Argonne Wakefield Accelerator (AWA) will be used to accelerate short duration (10 ps), high charge (100 nC) electron bunches from 2 MV to 20 MV for use in a variety of wakefield acceleration and measurement studies. The high charge is required since this drive bunch will generate the wakefields of interest in various test sections and their amplitudes are proportional to bunch charge. The short bunch duration is required to drive high-frequency wakefields without intra-bunch cancellation effects. The drive linac design was a balance between having a small wake function to maintain a drive bunch energy spread of ⩽10% and obtaining an adequate accelerating gradient of ⩾10 MV/m. This yielded a large aperture, low shunt impedance, high group velocity, L-band, standing-wave linac. Details of the design, fabrication, and testing are presented in the following