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Title: In situ measurement of low-Z material coating thickness on high Z substrate for tokamaks

Rutherford backscattering of energetic particles can be used to determine the thickness of a coating of a low-Z material over a heavier substrate. Simulations indicate that 5 MeV alpha particles from an {sup 241}Am source can be used to measure the thickness of a Li coating on Mo tiles between 0.5 and 15 μm thick. Using a 0.1 mCi source, a thickness measurement can be accomplished in 2 h of counting. This technique could be used to measure any thin, low-Z material coating (up to 1 mg/cm{sup 2} thick) on a high-Z substrate, such as Be on W, B on Mo, or Li on Mo. By inserting a source and detector on a moveable probe, this technique could be used to provide an in situ measurement of the thickness of Li coating on NSTX-U Mo tiles. A test stand with an alpha source and an annular solid-state detector was used to investigate the measurable range of low-Z material thicknesses on Mo tiles.
Authors:
; ; ; ; ;  [1] ; ;  [2]
  1. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)
  2. Department of Nuclear, Plasma, and Radiological Engineering, Center for Plasma Material Interaction, University of Illinois, Urbana, Illinois 61801 (United States)
Publication Date:
OSTI Identifier:
22303724
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 85; Journal Issue: 11; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALPHA PARTICLES; ALPHA SOURCES; AMERICIUM 241; BERYLLIUM; LITHIUM; MEV RANGE 01-10; MOLYBDENUM; NSTX DEVICE; RUTHERFORD BACKSCATTERING SPECTROSCOPY; SUBSTRATES; SURFACE COATING; THICKNESS