Low-energy neutral particle analysis by a time-of-flight method on JFT-2M

Journal Article · Thu Nov 01 04:00:00 EST 1990 · Review of Scientific Instruments; (USA)

DOI:https://doi.org/10.1063/1.1141574· OSTI ID:6225233

Miura, Y; Okano, F ^[1]

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1. Japan Atomic Energy Research Institute, Naka-machi, Naka-gun, Ibaraki-ken 311-01 (Japan)

A time-of-flight method is used to measure the energy spectrum of charge exchange atoms emitted from the JFT-2M plasma in the energy range below 1000 eV/amu. The neutral flux is chopped in bunches of about 0.8 {mu}s by a slotted cylinder. The rotating cylinder is driven by a turbomolecular pump. After the flight of 1.5 m the particles are detected by a secondary particle detector. This is an electron multiplier modified from a photomultiplier which can be gated for an intense photon. The signal from the electron multiplier is digitized at a sampling time of 0.2 {mu}s. To get good statistics of the arrival time distribution (ATD), eight or nine ATDs are averaged. Then the energy spectrum of charge exchange neutrals is measured by a 2 ms interval. The fast change ({le}2--6 ms) of energy spectra at the {ital L}/{ital H} and {ital H}/{ital L} transition is also reported. The average energy defined by {integral}{ital E}({ital d}{Gamma}/{ital dE}){ital dE}/{integral}({ital d}{Gamma}/{ital dE}){ital dE} increases by about 100 eV at the {ital H} transition like the increase of the ECE electron temperature at the edge. The neutral flux defined by {integral}({ital d}{Gamma}/{ital dE}){ital dE} decreases like the divertor {ital H}{sub {alpha}}/{ital D}{sub {alpha}} signal. In the energy distribution of the flux, the number of particles whose energy less than about 400 eV decrease by the {ital H} transition but those greater than 500 eV do not change or increase. The flux at 200 eV in the {ital H} phase is two times lower than that in the {ital L} phase.

• OSTI ID: 6225233
• Journal Information: Review of Scientific Instruments; (USA), Journal Name: Review of Scientific Instruments; (USA) Vol. 61:11; ISSN RSINA; ISSN 0034-6748
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
CHARGE EXCHANGE
CLOSED PLASMA DEVICES
ELECTRON MULTIPLIER DETECTORS
ENERGY RANGE
ENERGY SPECTRA
EQUIPMENT
EV RANGE
JFT-2M TOKAMAK
LABORATORY EQUIPMENT
MEASURING INSTRUMENTS
NEUTRAL PARTICLES
PARTICLES
PLASMA DIAGNOSTICS
PUMPS
RADIATION DETECTORS
SPECTRA
THERMONUCLEAR DEVICES
TIME-OF-FLIGHT METHOD
TOKAMAK DEVICES
TURBOMOLECULAR PUMPS
VACUUM PUMPS