Analysis of non-thermal electron cyclotron emission during electron cyclotron current drive experiments on the D3-D tokamak
Non-thermal electron distributions are diagnosed employing a fast scanning Michelson Interferometer which is capable of viewing the plasma vertically (constant B(sub toroidal)) along a chord at r/a approx. = .6 terminated by a highly absorptive Macor viewing dump, and horizontally at the midplane. Extraordinary (X) mode and Ordinary (O) mode polarizations of Electron Cyclotron Emission (ECE) in the second to the tenth harmonic of the fundamental electron cyclotron frequency have been collected under a variety of plasma conditions, during high power microwave injection at 60 GHz in the DIII-D Tokamak. Plasma refraction limits the data analysis to frequencies above the fifth harmonic where the data is characterized by a smooth, exponentially decreasing intensity, due to the high degree of harmonic overlap in this frequency range. Analysis of this data has shown the extreme sensitivity of this diagnostic to emission from high pitch angle particles. Results of delta function distribution calculations and distribution function fitting show that for a low density target plasma (central line averaged n(sub e) = 0.5 x 10(exp 13) cm(exp -3)), the emission is dominated by electrons near the trapping boundary at our viewing location, with average energies 400 keV less than (E) less than 500 keV during ECH. Under higher plasma target density conditions (central line averaged n(sub e) = 1.0 x 10(exp 13) cm(exp -3)) the population of electrons during ECH contributing to the emission increases in average energy to (E) approx. = 1.2 MeV as a result of the residual electric field induced by the primary transformer. Non-thermal electron densities (n(sub hot)) of approx. 1 x 10(exp 10) cm(exp -3) are estimated during the ECH phase while the post-ECH phase is characterized by a very diffuse (n(sub hot) approx. 5 x 10(exp 7) cm(exp -3)), energetic ((E) approx. 1.5 MeV), population in the trapped region of momentum space.
- Research Organization:
- Maryland Univ., College Park, MD (United States)
- OSTI ID:
- 6173533
- Resource Relation:
- Other Information: Ph.D. Thesis
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CYCLOTRON HARMONICS
EMISSION SPECTRA
DOUBLET-3 DEVICE
ECR HEATING
NON-INDUCTIVE CURRENT DRIVE
ELECTRONS
DISTRIBUTION FUNCTIONS
KINETIC ENERGY
ELECTRON DENSITY
GHZ RANGE 01-100
MICHELSON INTERFEROMETER
CLOSED PLASMA DEVICES
ELEMENTARY PARTICLES
ENERGY
FERMIONS
FREQUENCY RANGE
FUNCTIONS
GHZ RANGE
HARMONICS
HEATING
HIGH-FREQUENCY HEATING
INTERFEROMETERS
LEPTONS
MEASURING INSTRUMENTS
OSCILLATIONS
PLASMA HEATING
SPECTRA
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
700350* - Plasma Production
Heating
Current Drive
& Interactions- (1992-)
700320 - Plasma Diagnostic Techniques & Instrumentation- (1992-)