AVS 63rd International Symposium & Exhibition
    Vacuum Technology Monday Sessions
       Session VT-MoA

Paper VT-MoA3
Simulations of Vacuum Pumping and Beam Conditioning for CHESS-U Vacuum System

Monday, November 7, 2016, 2:20 pm, Room 104C

Session: Gas Dynamics, Simulation and Partial Pressure Analysis
Presenter: Yulin Li, Cornell Laboratory for Accelerator-Based Sciences and Education
Authors: Y. Li, Cornell Laboratory for Accelerator-Based Sciences and Education
X. Liu, Cornell Laboratory for Accelerator-Based Sciences and Education
J.S. Mershon, The College of Wooster
Correspondent: Click to Email
A major upgrade project (dubbed CHESS-U) is planned to elevate performance of Cornell High Energy Synchrotron Source (CHESS) to the state-of-art 3rd generation light sources. As a critical part of the CHESS-U project, about 80-m of Cornell Electron Storage Ring (CESR) is to be replaced with double-bend achromat (DBA) lattice to significantly reduce electron beam emittance. In this presentation, we will describe the conceptual design of the CHESS-U vacuum system, with emphasis on the vacuum pumping design and considerations. In the DBA lattice, multifunction dipole magnets with complex magnet poles prevent use of distributed ion pumps as in current CESR vacuum system. Instead, non-evaporable getter (NEG) strips are used to provide distributed vacuum pumping in the dipole vacuum chambers, as well as in the undulator vacuum chambers. Discrete pumps are used in the straights at available spaces between quadrupole and steering magnets. A test-particle Monte-Carlo simulation program, MolFlow+, is employed to evaluate pumping performances of the CHESS-U vacuum system in two aspects. First, we demonstrate that the planned vacuum pumping system can achieve and sustain required ultra-high vacuum level in CHESS-U operations. In addition, we will explore beam commissioning processes of the new vacuum chambers, and simulate the saturations of the NEG strips during the commissioning. These simulations will aid continuing design optimization for the CHESS-U vacuum system.