Witness gun for the Argonne Wakefield Accelerator

摘要

The witness gun for the Argonne Wakefield Accelerator (AWA) is a six-cell, copper, iris loaded, rf photocathode operating at 1.3 GHz in a (pi)/2 standing wave mode. An intense drive beam (up to 100 nC (at) 20 psec FWHM) used in the AWA project to excite (i.e. drive) wakefields in at least two separate test devices: a dielectric loaded cylindrical waveguide and a plasma cell. In both cases a low charge, low emittance witness beam (0.1 nC charge, 1 (pi)mm-mrad 90% physical emittance) is required to probe (i.e. witness) the wakefields left behind by the drive beam. This paper will primarily discuss the recent progress in the construction of the witness gun, while also briefly summarizing the central design issues of the gun. A brief status report on the dielectric witness gun option is also included. The authors conclude with a short statement on the near term future plans.