High Frequency, High Gradient Dielectric Wakefield Acceleration Experiments at SLAC and BNL

Abstract

Given the recent success of >GV/m dielectric wakefield accelerator (DWA) breakdown experiments at SLAC, and follow-on coherent Cerenkov radiation production at the UCLA Neptune, a UCLA-USC-SLAC collaboration is now implementing a new set of experiments that explore various DWA scenarios. These experiments are motivated by the opportunities presented by the approval of FACET facility at SLAC, as well as unique pulse-train wakefield drivers at BNL. The SLAC experiments permit further exploration of the multi-GeV/m envelope in DWAs, and will entail investigations of novel materials (e.g. CVD diamond) and geometries (Bragg cylindrical structures, slab-symmetric DWAs), and have an over-riding goal of demonstrating >GeV acceleration in ~33 cm DWA tubes. In the nearer term before FACET's commissioning, we are planning measurements at the BNL ATF, in which we drive ~50-200 MV/m fields with single pulses or pulse trains. These experiments are of high relevance to enhancing linear collider DWA designs, as they will demonstrate potential for efficient operation with pulse trains.

Wakefield radiation from the open end of an internally coated metallic tube

“…The minimum value of the attenuation coefficient accounts for ς ¼ 1. Note, that according to (2), the attenuation coefficient A does not change with the transition from ς to ς −1 , since the curves for ς ¼ 3 and ς ¼ 1=3 are identical.…”

“…Recently, a new traveling wave structure has been proposed [1]: an internally coated metallic pipe (ICMP), which has only a single slowly propagating (phase velocity is equal to the velocity of light) TM 01 mode. Because of an absence of the high slowly propagating modes, the above structure could be effectively used for particle acceleration or generation of monochromatic radiation [2][3][4][5]. The experimental study of an ICMP type structure is currently under development at AREAL test facility [6].…”

rf breakdown tests of mm-wave metallic accelerating structures

“…Another approach to reaching high accelerating gradients at higher frequencies involves dielectric wakefield accelerators. These schemes have been tested at SLAC FACET [51] and elsewhere [52][53][54][55]. To our knowledge, in these experiments there were no systematic studies of rf breakdown probability.…”

Experimental measurements of rf breakdowns and deflecting gradients in mm-wave metallic accelerating structures

“…Henke and Bruns [16][17][18] and Chou and Kroll at SLAC [19] designed a mm-wave muffin-tin planar accelerator structure. Another approach to reach higher accelerating gradients at higher frequencies involves dielectric wakefield accelerators [20][21][22]. At Argonne these were tested as well as dielectric wakefield-excited structures [23][24][25][26].…”