Spatially distributed scintillator arrays for diagnosing runaway electron transport and energy behavior in tokamaks

Journal Article · Fri Oct 15 00:00:00 EDT 2010 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.3475710· OSTI ID:22055863

James, A N; Hollmann, E M; Tynan, G R ^[1]

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1. UC San Diego Center for Energy Research, La Jolla, California 92093-0417 (United States)

We present details of a new bismuth germanate [Bi{sub 4}Ge{sub 3}O{sub 12} (BGO)] scintillator array used to diagnose the transport and energy behavior of runaway electrons (REs) in DIII-D. BGO exhibits important properties for these compact detectors including high light yield which sufficiently excites photodiode detectors (8500 photons/MeV), high density and atomic numbers of constituent materials which maximizes sensitivity, and relative neutron blindness which minimizes complications in data interpretation. The detectors observe primarily hard x-ray radiation emitted in a forward beamed pattern by RE when they strike first wall materials or bulk ions and neutrals in the plasma, although we also address photoneutron signals. The arrangement of the array enables time resolved location of x-ray emission and associated asymmetries which help identify instabilities and confinement properties of RE. By shielding a subset of detectors with different thicknesses of lead, and with interpretative support of the code EGSNRC, we also measure RE energy, although due to the often distributed nature of RE strike points and the forward beamed character of emitted hard x-rays, we restrict interpretation as a lower bound for RE energy.

• OSTI ID: 22055863
• Journal Information: Review of Scientific Instruments, Vol. 81, Issue 10; Other Information: (c) 2010 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BGO DETECTORS
BISMUTH GERMANATES
DENSITY
DOUBLET-3 DEVICE
FIRST WALL
HARD X RADIATION
INSTABILITY
LEAD
PHOTODIODES
PHOTONEUTRONS
PLASMA
PLASMA CONFINEMENT
RUNAWAY ELECTRONS
SENSITIVITY
SHIELDING
TIME RESOLUTION
VISIBLE RADIATION