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H Ly-alpha transmittance of thin foils of C, Si/C, and Al/C for keV particle detectorsA class of instruments designed for remote sensing of space plasmas by measuring energetic neutral atoms (ENA) uses a thin foil as both a signal generator and a light shield. An ENA imager must look directly at the ENA source region, which is also usually an intense source of H Ly-alpha (1216 A) photons. It is desirable to minimize the energy threshold for ENA detectors, at the same time maximizing the blocking of H Ly-alpha. Optimizing filter design to meet these two contrary requirements has led us to measure the transmittance of thin C, Si/C, and Al/C foils at H Ly-alpha. Our results indicate that (1) transmittance of less than 0.0007 can be achieved with 7 micro-g/sq cm Si on 1.7 micro-g/sq cm C; (2) an Si/C composite foil with a thin carbon layer is more effective in blocking UV radiation while having the lowest energy threshold of all the foils measured; and (3) transmittance of Si/C foils of known Si and C thicknesses cannot be accurately predicted, but must be measured.
Document ID
19930045769
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Drake, V. A.
(NASA Headquarters Washington, DC United States)
Sandel, B. R.
(NASA Headquarters Washington, DC United States)
Jenkins, D. G.
(NASA Headquarters Washington, DC United States)
Hsieh, K. C.
(Arizona Univ. Tucson, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1992
Publication Information
Publication: In: Instrumentation for magnetospheric imagery; Proceedings of the Meeting, San Diego, CA, July 21, 22, 1992 (A93-29751 10-19)
Publisher: Society of Photo-Optical Instrumentation Engineers
Subject Category
Spacecraft Instrumentation
Accession Number
93A29766
Funding Number(s)
CONTRACT_GRANT: NASW-1676
CONTRACT_GRANT: NASW-1419
Distribution Limits
Public
Copyright
Other

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