First measurement of time-resolved neutron yield on JT-60U using a microfission chamber

Journal Article · Fri Oct 01 04:00:00 EDT 2004 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1785261· OSTI ID:20636688

Hayashi, T; Nishitani, T; Ishikawa, M ^[1]

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1. Japan Atomic Energy Research Institute, Naka-machi, Ibaraki 319-0193 (Japan)

Microfission chambers, which are pencil sized ionization chamber containing fissile material inside, will be installed in the vacuum vessel as neutron monitors for International Thermonuclear Experimental Reactor (ITER). We have performed first measurements of the detector installed between the vacuum vessel and toroidal coils on JT-60U. The technical validity as a neutron monitor, such as magnetic field effect and electromagnetic noises from the plasma and heating devices, has been investigated. The detector had an excellent linearity with a {sup 235}U fission chamber as a neutron monitor on JT-60U with the standard deviation of 3% except for some noise signals. The electromagnetic noises were caused by neutral beam injection (NBI) breakdowns, probably due to long wiring between the detector and the preamplifier. In case of plasma disruption, improper signals have not been observed. The magnetic field effect also has not been observed up to 2 T. In JT-60U, we confirmed availability of the micro fission chamber as a neutron monitor over three decades of neutron source strength up to 1.3x10{sup 16} neutrons/s with 1 ms temporal resolution. The biggest weakness in the detector was its noise sensitivity to NBI breakdowns. Therefore, by suppressing the electromagnetic noise, microfission chambers can be available as neutron monitors for ITER.

• OSTI ID: 20636688
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 75; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
BEAM INJECTION
BEAM INJECTION HEATING
EXPERIMENTAL REACTORS
FISSILE MATERIALS
FISSION CHAMBERS
ITER TOKAMAK
JT-60U TOKAMAK
MAGNETIC FIELDS
NEUTRON BEAMS
NEUTRON MONITORS
NEUTRON SOURCES
NOISE
PLASMA CONFINEMENT
PLASMA DIAGNOSTICS
PLASMA DISRUPTION
TIME RESOLUTION
URANIUM 235