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Proceedings Paper

FUV quantum efficiency degradation of cesium iodide photocathodes caused by exposure to thermal atomic oxygen
Author(s): Jason McPhate; Joshi Anne; John Bacinski; Bruce Banks; Carey Cates; Paul Christensen; Brett Cruden; Larry Dunham; Eric Graham; David Hughes; Randy Kimble; Olivia Lupie; Malcolm Niedner; Steven Osterman; Steven Penton; Charles Proffitt; Diane Pugel; Oswald Siegmund; Thomas Wheeler
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Paper Abstract

The color dependence of the measured decline of the on-orbit sensitivity of the FUV channel of the HST Cosmic Origins Spectrograph (HST-COS) indicated the principal loss mechanism to be degradation of the cesium iodide (CsI) photocathode of the open-faced FUV detector. A possible cause of this degradation is contamination by atomic oxygen (AO), prompting an investigation of the interaction of AO with CsI. To address this question, opaque CsI photocathodes were deposited on stainless steel substrates employing the same deposition techniques and parameters used for the photocathodes of the HST-COS FUV detector. The as-deposited FUV quantum efficiency of these photocathodes was measured in the 117-174 nm range. Several of the photocathodes were exposed to varying levels of thermalized, atomic oxygen (AO) fluence (produced via an RF plasma). The post AO exposure QE's were measured and the degradation of sensitivity versus wavelength and AO fluence are presented.

Paper Details

Date Published: 15 September 2011
PDF: 10 pages
Proc. SPIE 8145, UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XVII, 81450I (15 September 2011); doi: 10.1117/12.897024
Show Author Affiliations
Jason McPhate, Univ. of California, Berkeley (United States)
Joshi Anne, Lockheed Martin Space Systems Co. (United States)
John Bacinski, NASA Goddard Space Flight Ctr. (United States)
Bruce Banks, NASA Glenn Research Ctr. (United States)
Carey Cates, Lockheed Martin Space Systems Co. (United States)
Paul Christensen, Lockheed Martin Space Systems Co. (United States)
Brett Cruden, NASA Ames Research Ctr. (United States)
Larry Dunham, NASA Goddard Space Flight Ctr. (United States)
Eric Graham, NASA Goddard Space Flight Ctr. (United States)
David Hughes, NASA Goddard Space Flight Ctr. (United States)
Randy Kimble, NASA Goddard Space Flight Ctr. (United States)
Olivia Lupie, NASA Goddard Space Flight Ctr. (United States)
Malcolm Niedner, NASA Goddard Space Flight Ctr. (United States)
Steven Osterman, Univ. of Colorado at Boulder (United States)
Steven Penton, Univ. of Colorado at Boulder (United States)
Charles Proffitt, Space Telescope Science Institute (United States)
Diane Pugel, NASA Goddard Space Flight Ctr. (United States)
Oswald Siegmund, Univ. of California, Berkeley (United States)
Thomas Wheeler, Space Telescope Science Institute (United States)


Published in SPIE Proceedings Vol. 8145:
UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XVII
Oswald H. Siegmund, Editor(s)

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