title: In situ measurement of low-Z material coating thickness on high Z substrate for tokamaks.
abstract: 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 (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(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.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: D
authors.initials: D
authors.lastname: Mueller
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: A L
authors.initials: AL
authors.lastname: Roquemore
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: M
authors.initials: M
authors.lastname: Jaworski
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: C H
authors.initials: CH
authors.lastname: Skinner
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: J
authors.initials: J
authors.lastname: Miller
authors.affiliation: Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
authors.forename: A
authors.initials: A
authors.lastname: Creely
authors.affiliation: Department of Nuclear, Plasma, and Radiological Engineering, Center for Plasma Material Interaction, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: P
authors.initials: P
authors.lastname: Raman
authors.affiliation: Department of Nuclear, Plasma, and Radiological Engineering, Center for Plasma Material Interaction, University of Illinois, Urbana, Illinois 61801, USA.
authors.forename: D
authors.initials: D
authors.lastname: Ruzic