TY - JOUR
T1 - High-efficiency fast scintillators for "optical" soft x-ray arrays for laboratory plasma diagnostics
AU - Delgado-Aparicio, L. F.
AU - Stutman, D.
AU - Tritz, K.
AU - Vero, R.
AU - Finkenthal, M.
AU - Suliman, G.
AU - Kaita, R.
AU - Majeski, R.
AU - Stratton, B.
AU - Roquemore, L.
AU - Tarrio, C.
PY - 2007/8/20
Y1 - 2007/8/20
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=36749037175&partnerID=8YFLogxK
U2 - 10.1364/AO.46.006069
DO - 10.1364/AO.46.006069
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AN - SCOPUS:36749037175
SN - 1559-128X
VL - 46
SP - 6069
EP - 6075
JO - Applied Optics
JF - Applied Optics
IS - 24
ER -