ANL, Argonne, USA
Euclid TechLabs, LLC, Solon, Ohio, USA
Illinois Institute of Technology, Chicago, Illinois, USA
The AWA Facility is presently undergoing several upgrades that will enable it to further study wakefield acceleration driven by high charge electron beams. The facility employs an L-band photocathode RF gun to generate high charge short electron bunches, which are used to drive wakefields in dielectric loaded structures as well as in metallic structures (iris loaded, photonic band gap, etc). Several facility upgrades are underway: (a) a new RF gun with a higher quantum efficiency photocathode will replace the RF gun that has been used to generate the drive bunches; (b) the existing RF gun will be used to generate a witness beam to probe the wakefields; (c) three new L-band RF power stations, each providing 25 MW, will be added to the facility; (d) five linac structures will be added to the drive beamline, bringing the beam energy up from 15 MeV to 75 MeV. The drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The goal of future experiments is to reach accelerating gradients of several hundred MV/m and to extract RF pulses with GW power level.
Euclid TechLabs, LLC, Solon, Ohio, USA
ANL, Argonne, USA
IIT, Chicago, Illinois, USA
Significant progress has been made in the development of high gradient rf driven dielectric accelerating structures (DLA). One principal effect limiting further advances in this technology is the problem of multipactor. The fraction of the power absorbed at saturation in DLA experiments was found to increase with the incident power, with more than 30% of the incident power per unit length being absorbed. We studied a possibility of multipactor mitigation by introduction of surface grooves (transverse and longitudinal) to interrupt the resonant trajectories of electrons in the multipactor discharge. Four DLA structures based on quartz tubes with transverse and longitudinal grooves of various dimensions were designed. In this paper we report simulation results and plans for high-power tests of these structures.
Euclid TechLabs, LLC, Solon, Ohio, USA
ANL, Argonne, USA
Diamond has been proposed as a dielectric material for dielectric loaded accelerating (DLA) structures. It has a very low microwave loss tangent, the highest available thermoconductive coefficient and high RF breakdown field. In this paper we report the results from a wakefield breakdown test of diamond-loaded rectangular accelerating structure and development of a cylindrical diamond DLA. We expect to achieve field levels on the order of 100 MV/m in the structure using the 100nC beam at the Argonne Wakefield Accelerator Facility. Single crystal diamond plates produced by chemical vapor deposition (CVD) are used in the structure. The structure is designed to yield up to 0.5 GV/m fields on the diamond surface to test it for breakdown. A surface analysis of the diamond is performed before and after the beam test.
