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High energy x-ray measurements during lower hybrid current drive on the Alcator C tokamak

Technical Report ·
OSTI ID:5955820
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High energy x-ray emission (E/sub ..gamma../ > 20 keV) from superthermal plasma electrons during lower hybrid current drive on the Alcator C tokamak has been measured using Sodium Iodide (NaI) scintillation spectroscopy. The x-ray spectra are generally linear on a semi-log plot of count rate vs. photon energy and extend out to several hundred keV. For the range of densities (anti n/sub e/ approx. = 0.3 - 0.8x10/sup 14/cm/sup -3/) over which current drive was performed on Alcator, there was negligible emission before the injection of radiofrequency (rf) wave power. The radial profiles of the emission were also measured and indicate that the current carrying, high energy electrons exist primarily within the inner half (r/a < 1/2) of the plasma column. Plasma parameter scans produced variations in the x-ray emission profiles that are consistent with changes in the launched Fourier power spectrum, and the conditions imposed by lower hybrid wave accessibility. In addition, the velocity space distribution function of the energetic tail electrons has been determined using the angular variation in the x-ray emission.
Research Organization:
Massachusetts Inst. of Tech., Cambridge (USA). Plasma Fusion Center
DOE Contract Number:
AC02-78ET51013
OSTI ID:
5955820
Report Number(s):
PFC/JA-86-11; ON: DE86009046
Country of Publication:
United States
Language:
English

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Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700104* -- Fusion Energy-- Plasma Research-- Plasma Kinetics-Experimental-- (-1987)
ALCATOR DEVICE
CLOSED PLASMA DEVICES
CURRENT-DRIVE HEATING
ELECTRIC HEATING
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
HEATING
HIGH-FREQUENCY HEATING
JOULE HEATING
LEPTONS
LOWER HYBRID HEATING
MEASURING INSTRUMENTS
NAI DETECTORS
PLASMA HEATING
RADIATION DETECTORS
RESISTANCE HEATING
SCINTILLATION COUNTERS
SOLID SCINTILLATION DETECTORS
SPECTRA
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
X-RAY SPECTRA