High-efficiency fast scintillators for "optical" soft x-ray arrays for laboratory plasma diagnostics

L. F. Delgado-Aparicio*, D. Stutman, K. Tritz, R. Vero, M. Finkenthal, G. Suliman, R. Kaita, R. Majeski, B. Stratton, L. Roquemore, C. Tarrio

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

11 Scopus citations

Abstract

Scintillator-based "optical" soft x-ray (OSXR) arrays have been investigated as a replacement for the conventional silicon (Si)-based diode arrays used for imaging, tomographic reconstruction, magnetohy-drodynamics, transport, and turbulence studies in magnetically confined fusion plasma research. An experimental survey among several scintillator candidates was performed, measuring the relative and absolute conversion efficiencies of soft x rays to visible light. Further investigations took into account glass and fiber-optic faceplates (FOPs) as substrates, and a thin aluminum foil (150 nm) to reflect the visible light emitted by the scintillator back to the optical detector. Columnar (crystal growth) thallium-doped cesium iodide (CsI:Tl) deposited on an FOP, was found to be the best candidate for the previously mentioned plasma diagnostics. Its luminescence decay time of the order of ∼1-10 μs is thus suitable for the 10 μs time resolution required for the development of scintillator-based SXR plasma diagnostics. A prototype eight channel OSXR array using CsI:Tl was designed, built, and compared to an absolute extreme ultraviolet diode counterpart: its operation on the National Spherical Torus Experiment showed a lower level of induced noise relative to the Si-based diode arrays, especially during neutral beam injection heated plasma discharges. The OSXR concept can also be implemented in less harsh environments for basic spectroscopic laboratory plasma diagnostics.

Original languageEnglish
Pages (from-to)6069-6075
Number of pages7
JournalApplied Optics
Volume46
Issue number24
DOIs
StatePublished - 20 Aug 2007
Externally publishedYes

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