Oblique electron cyclotron emission for electron distribution studies (invited)

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1147841· OSTI ID:451764

Preische, S ^[1]; Efthimion, P C; Kaye, S M ^[2]

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1. Association Euratom-Commissariat a l`Energie Atomique sur la Fusion, Centre d`Etudes de Cadarache, 13108 St. Paul-lez-Durance (France)
2. Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543-0451 (United States)

Electron cyclotron emission (ECE) at an oblique angle to the magnetic field provides a means of probing the electron distribution function both in energy and physical space through changes in and constraints on the relativistic electron cyclotron resonance condition. Diagnostics based on this Doppler shifted resonance are able to study a variety of electron distributions through changes in the location of the resonance in physical or energy space accomplished by changes in the viewing angle and frequency, and the magnetic field. For the case of observation across a changing magnetic field, such as across the tokamak midplane, the constraint on the resonance condition for real solutions to the dispersion relation can constrain the physical location of optically thin emission. A new Oblique ECE diagnostic was installed and operated on the PBX-M tokamak for the study of energetic electrons during lower hybrid current drive. It has a view 33{degree} with respect to perpendicular in the tokamak midplane, receives second harmonic X-mode emission, and is constrained to receive single pass emission by SiC viewing dumps on the tokamak walls. Spatial localization of optically thin emission from superthermal electrons (50{endash}100 keV) was obtained by observation of emission upshifted from a thermal cyclotron harmonic. The localized measurements of the electron energy distribution and the superthermal density profile made by this diagnostic demonstrate its potential to study the spatial transport of energetic electrons on fast magnetohydrodynamic time scales or anomalous diffusion time scales. Oblique ECE can also be used to study electron distributions that may have a slight deviation from a Maxwellian by localizing the emission in energy space. (Abstract Truncated)

• Research Organization: Princeton Plasma Physics Laboratory
• DOE Contract Number: AC02-76CH03073
• OSTI ID: 451764
• Report Number(s): CONF-960543--
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 1 Vol. 68; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
CYCLOTRON RADIATION
DISTRIBUTION FUNCTIONS
DOPPLER EFFECT
ELECTRON CYCLOTRON-RESONANCE
LOWER HYBRID CURRENT DRIVE
MAGNETOHYDRODYNAMICS
MEASURING METHODS
PBX DEVICES
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA HEATING
PLASMA RADIAL PROFILES
RESOLUTION
X RADIATION