R&D ERL: Photocathode Deposition and Transport System

Pate, D. ; Ben-Zvi, I. ; Rao, T. ; Burrill, R. ; Todd, R. ; Smedley, J. ; Holmes, D.

关键词: CATHODES;    CLEANING;    DEPOSITION;    DESIGN;    ELECTRON GUNS;    ENERGY RECOVERY;    ION SOURCES;    LIFETIME;    LINEAR ACCELERATORS;    PHOTOCATHODES;    QUANTUM EFFICIENCY;    RF SYSTEMS;    SUPERCONDUCTING CAVITY RESONATORS;    TRANSPORT relativistic heavy io;   

DOI  :  10.2172/1013451
RP-ID  :  BNL--90928-2010-IR
PID  :  OSTI ID: 1013451
Others  :  R&D Project: KBCH139
Others  :  Other: KB0202011
Others  :  TRN: US1102648

学科分类：核物理和高能物理

美国|英语

来源: SciTech Connect

【 摘 要 】

The purpose of the photocathode deposition and transport system is to (1) produce a robust, high yield multialkali photocathode and (2) have a method of transporting the multialkali photocathode for insertion into a super conducting RF electron gun. This process is only successful if a sufficient quantum efficiency lifetime of the cathode, which is inserted in the SRF electron gun, is maintained. One important element in producing a multialkali photocathode is the strict vacuum requirements of 10{sup -11} torr to assure success in the production of longlived photocathodes that will not have their QE or lifetime depleted due to residual gas poisoning in a poor vacuum. A cutaway view of our third generation deposition system is shown in figure 1. There are certain design criteria and principles required. One must be able to install, remove, rejuvenate and replace a cathode without exposing the source or cathode to atmosphere. The system must allow one to deposit Cs, K, and Sb on a cathode tip surface at pressures in the 10{sup -10} to 10{sup -9} torr range. The cathode needs to be heated to as high as 850 C for cleaning and maintained at 130 C to 150 C during deposition. There should also be the capability for in-situ QE measurements. In addition the preparation of dispenser photocathodes must be accounted for, thus requiring an ion source for cathode cleaning. Finally the transport cart must be mobile and be able to negotiate the ERL facility labyrinth.