HIGH POWER RF TESTING OF DIELECTRIC-LOADED ACCELERATING STRUCTURES

摘要

High gradient accelerating structures using dielectriclined circular waveguides have been developed for a number of years at Argonne National Laboratory. Up to date, 8MV/m of accelerating gradient has been reached (alumina) without breakdown; multipactor and dielectric-joint breakdown have been discovered and modelled; new methods to improve the performance of Dielectric-Loaded Accelerating (DLA) structures are studied. In this article, we first briefly review major experimental results of high power rf testing on DLA structures carried out in recent years. In the second part of this paper, ways to achieve higher gradient for DLA structures are proposed: 1) smaller ID and longitudinal gap free DLA structures to reduce multipactor and obtain higher gradient; 2) new coaxial type coupler to avoid dielectric gap and improve impedance matching; 3) double layered DLA structure to reduce rf loss and enhance shunt impedance as well.