Characterization of the CEBAF 100 kV DC GaAs photoelectron gun vacuum system

被引：16

作者：

Stutzman, M. L. ^{[1
]}

Adderley, P. ^{[1
]}

Brittian, J. ^{[1
]}

Clark, J. ^{[1
]}

Grames, J. ^{[1
]}

Hansknecht, J. ^{[1
]}

Myneni, G. R. ^{[1
]}

Poelker, M. ^{[1
]}

机构：

[1] Thomas Jefferson Natl Accelerator Facil, Polarized Source, Newport News, VA 23606 USA

来源：

NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT | 2007年 / 574卷 / 02期

关键词：

polarized electron source; photoinjector; electron gun; non-evaporable getter (NEG); pump speed; outgassing;

D O I：

10.1016/j.nima.2007.01.170

中图分类号：

TH7 [仪器、仪表];

学科分类号：

0804 ; 080401 ; 081102 ;

摘要：

A vacuum system with pressure in the low ultra-high vacuum (UHV) range is essential for long photocathode lifetimes in DC high voltage GaAs photoguns. A discrepancy between predicted and measured base pressure in the CEBAF photoguns motivated this study of outgassing rates of three 304 stainless steel chambers with different pretreatments and pump speed measurements of non-evaporable getter (NEG) pumps. Outgassing rates were measured using two independent techniques. Lower outgassing rates were achieved by electropolishing and vacuum firing the chamber. The second part of the paper describes NEG pump speed measurements as a function of pressure through the lower part of the UHV range. Measured NEG pump speed is high at pressures above 5 x 10(-11) Torr, but may decrease at lower pressures depending on the interpretation of the data. The final section investigates the pump speed of a locally produced NEG coating applied to the vacuum chamber walls. These studies represent the first detailed vacuum measurements of CEBAF photogun vacuum chambers. (C) 2007 Elsevier B.V. All rights reserved.

引用

页码：213 / 220

页数：8