An evaluation of multilayer mirrors for the soft x ray and extreme ultraviolet wavelength range that were irradiated with neutrons

S. P. Began*, M. J. May, V. Soukhanovskii, M. Finkenthal, H. W. Moos, E. H. Farnum, F. W. Clinard, C. Tarrio, R. Watts

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review

3 Scopus citations

Abstract

The Plasma Spectroscopy Group at the Johns Hopkins University develops high photon throughput multilayer mirror (MLM) based soft x ray and extreme ultraviolet (XUV 10 Å<λ<304 Å) spectroscopic diagnostics for magnetically confined fusion plasmas. The D-T reactions in large fusion reactor type devices such as the International Thermonuclear Experimental Reactor will produce neutrons at a rate as high as 5×1019 n s-1. The MLMs, which are used as dispersive and focusing optics, will not be shielded from these neutrons. In an effort to assess the potential radiation damage, four MLMs (No. 1: Mo/Si, d=87.8 Å, Zerodur substrate with 50 cm concave spherical curvature; No. 2: W/B4C, d=22.75 Å, Si wafer substrate; No. 3: W/C, d=25.3 Å, Si wafer substrate; and No. 4: Mo/Si, d=186.6 Å, Si wafer substrate) were irradiated with fast neutrons at the Los Alamos Spallation Radiation Effects Facility (LASREF). The neutron beam at LASREF has an energy distribution that peaks at 1-2 MeV with a tail that extends out to 100 MeV. The MLMs were irradiated to a fast neutron fluence of 1.1×1019 n cm-2 at 270-300 °C. A comparison between the dispersive and reflective characteristics of the irradiated MLMs and the corresponding qualities of control samples will be given.

Original languageEnglish
Pages (from-to)757-760
Number of pages4
JournalReview of Scientific Instruments
Volume68
Issue number1
DOIs
StatePublished - Jan 1997

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