Fast-ion D{alpha} measurements of the fast-ion distribution (invited)

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

DOI:https://doi.org/10.1063/1.3478739· OSTI ID:22055806

Heidbrink, W W ^[1]

---

1. University of California, Irvine, California 92697 (United States)

The fast-ion D{alpha} (FIDA) diagnostic is an application of charge-exchange recombination spectroscopy. Fast ions that neutralize in an injected neutral beam emit Balmer-{alpha} light with a large Doppler shift. The spectral shift is exploited to distinguish the FIDA emission from other bright sources of D{alpha} light. Background subtraction is the main technical challenge. A spectroscopic diagnostic typically achieves temporal, energy, and transverse spatial resolution of {approx}1 ms, {approx}10 keV, and {approx}2 cm, respectively. Installations that use narrow-band filters achieve high spatial and temporal resolution at the expense of spectral information. For high temporal resolution, the bandpass-filtered light goes directly to a photomultiplier, allowing detection of {approx}50 kHz oscillations in FIDA signal. For two-dimensional spatial profiles, the bandpass-filtered light goes to a charge-coupled device camera; detailed images of fast-ion redistribution at instabilities are obtained. Qualitative and quantitative models relate the measured FIDA signals to the fast-ion distribution function. The first quantitative comparisons between theory and experiment found excellent agreement in beam-heated magnetohydrodynamics (MHD)-quiescent plasmas. FIDA diagnostics are now in operation at magnetic-fusion facilities worldwide. They are used to study fast-ion acceleration by ion cyclotron heating, to detect fast-ion transport by MHD modes and microturbulence, and to study fast-ion driven instabilities.

• OSTI ID: 22055806
• 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
CHARGE EXCHANGE
CHARGE-COUPLED DEVICES
CHARGED-PARTICLE TRANSPORT
CYCLOTRONS
DISTRIBUTION FUNCTIONS
DOPPLER EFFECT
IONS
KEV RANGE
KHZ RANGE
MAGNETOHYDRODYNAMICS
OSCILLATIONS
PARTICLE BEAMS
PHOTOMULTIPLIERS
PLASMA HEATING
QUIESCENT PLASMA
RECOMBINATION
SIGNALS
SPATIAL RESOLUTION
SPECTRAL SHIFT
SPECTROSCOPY
VISIBLE RADIATION