Simultaneous measurement of current and plasma density profiles in the TEXT Tokamak

Conference · Thu Aug 01 04:00:00 EDT 1985

OSTI ID:5171454

Thomas, D M; West, W P; Zheng, S B

A method of obtaining information on the current density profile j(r) and relative plasma density n(r) in a tokamak is discussed. Both measurements rely on analysis of the fluorescence emitted by a high energy neutral lithium beam as it traverses the plasma. Superimposed on the neutral beam trajectory is a linearly polarized dye laser beam tuned to the Doppler-shifted ..pi.. component of the Zeeman-split resonance line. Thus the light emitted by the beam consists of laser-induced fluorescence as well as collisionally induced fluorescence. As the Zeeman components are polarized relative to the local magnetic field direction, rotation of the plane of polarization of the laser at frequency ..omega.. will modulate the laser induced fluorescence at 2..omega.., since the resonance condition is satisfied for the ..pi.. components twice each cycle. Phase analysis of the modulated fluorescence relative to a reference phase taken from the laser polarization direction permits us to accurately measure the local magnetic field direction at various radial positions inside the plasma. The poloidal magnetic field structure, and hence the plasma current distribution, may be deduced from the direction of the magnetic field (equal to the direction of laser polarization at maximum fluorescence) and the known magnitude of the toroidal magnetic field. Similarly, the relative plasma density at various r may be determined from a study of the collisionally induced fluorescence signal.

• Research Organization: GA Technologies, Inc., San Diego, CA (USA); Texas Univ., Austin (USA). Fusion Research Center
• DOE Contract Number: AC03-84ER53158
• OSTI ID: 5171454
• Report Number(s): GA-A-18122; CONF-8509127-3; ON: DE85017679
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700102* -- Fusion Energy-- Plasma Research-- Diagnostics
ALKALI METALS
ATOMIC BEAMS
BEAMS
CLOSED PLASMA DEVICES
CURRENTS
DYE LASERS
ELECTRIC CURRENTS
ELEMENTS
EMISSION SPECTROSCOPY
FLUORESCENCE
FLUORESCENCE SPECTROSCOPY
LASERS
LIQUID LASERS
LITHIUM
LUMINESCENCE
METALS
PLASMA DENSITY
PLASMA DIAGNOSTICS
SPECTROSCOPY
TEXT DEVICES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES