AVS 59th Annual International Symposium and Exhibition
    Vacuum Technology Tuesday Sessions
       Session VT-TuA

Paper VT-TuA11
Vacuum System of Cornell Energy-Recovery LINAC Prototype Injector

Tuesday, October 30, 2012, 5:20 pm, Room 14

Session: Accelerator and Ultra-Clean Vacuum Systems
Presenter: Y. Li, Cornell University
Authors: Y. Li, Cornell University
X. Liu, Cornell University
K.W. Smolenski, Cornell University
I. Bazarov, Cornell University
B.M. Dunham, Cornell University
Correspondent: Click to Email
A prototype electron injector was designed, constructed and operated at CLASSE, as an important first step toward the Cornell ERL (Energy-Recovery LINAC) based synchrotron radiation facility. The injector is designed to generate average beam current up to 100-mA, and electron beam energy ranging 5-MeV to 15 MeV. Main features of the injector include a laser-driven photo-emission electron source, a cryo-module containing superconducting RF cavities, electron beam transport beamlines equipped with a suite of beam diagnostic instrument, and a 600-kW electron beam stop. Recently, significant milestones were reached for the prototype injector. Most noticeably, we have achieved an average beam current of 52-mA at a beam energy of 5-MeV from activated GaAs photo-cathodes, breaking a long-standing world record of 32-mA from a laser-driven photo-emission electron source. There are many challenges in vacuum system design for the prototype injector. It needs to provide an extremely-high vacuum (XHV) environment for the photo-cathodes, flexibilities in beam transport beamlines for development of beam instrumentation, as well as sufficient vacuum pumping capacity to handle very large dynamic gas-load at the beam stop. In the past 3+ years of operations, the injector vacuum system has performed satisfactorily. To confirm the pumping performance, we calculated pressure profile along the main transport beamlines during the high beam current runs, and calculated pressure profile agreed well with the measured pressure profile. In this paper, we describe the design and the operational experiences of the prototype injector vacuum system, and address remaining operational issues arising from high beam current operations.