Vacuum behavior of the x ray lithography source
Abstract
Photon stimulated desorption (PSD) is the major source of the gas load in electron storage rings and therefore strongly influences both beam lifetime and beam quality. The 200 MeV compact ring at the NSLS is an ideal tool to study PSD since its energy can be varied from 60 to 200 MeV and the photoelectrons produced by synchrotron radiation can be measured in clearing electrodes installed to collect trapped ions. Using these electrodes we show: (1) photoelectrons are produced only by photons having energy above 10eV, and (2) desorption is proportional to the number of photoelectrons. Using calibrated gauges we conclude that (1) time-integrated beam current of 10-20 Ampere-hours is needed for initial vacuum chamber clean-up, (2) venting the chamber to dry nitrogen has a negligible effect on subsequent desorption, and (3) venting to air requires about 10 Ampere-hours of beam conditioning.
- Publication:
-
Presented at the 38th National Symposium of the American Vacuum Society
- Pub Date:
- November 1991
- Bibcode:
- 1991avs..sympR..11H
- Keywords:
-
- Cleaning;
- Lithography;
- Radiation Sources;
- Synchrotrons;
- Vacuum Systems;
- X Ray Sources;
- Beam Currents;
- Superconducting Magnets;
- Instrumentation and Photography