Post-Coupler and Stem Current Measurements for High Current CW Drift-Tube Linacs

Post-coupler characteristics have been measured on a model Alvarez tank for drift-tube-to-outer tank diameter ratios from 0.10 to 0.25. A maximum ratio beyond which field stabilization is not possible and a minimum ratio where stabilization is difficult have been determined. Field stabilization has been studied using two to twenty-one post couplers in a 22 cell tank. A sensitive dependence of the drift-tube stem currents near the tank end walls on the end cell geometry has been found.