Studies of the trapped particle and ion temperature gradient instabilities in the Columbia Linear Machine

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5924975

Mathey, O H

In the first part of the work, the effects of weak Coulomb and neutral collisions on the collisionless curvature driven trapped particle mode are studied in the Columbia Linear Machine (CLM) (Phys. Rev. Lett. 57, 1729, (1986)). Low Coulomb collisionality yields a small stabilizing correction to the magnetohydrodynamic (MHD) collisionless mode, which scales as v, using the Krook model, and {nu}{sub ec}{sup 1/2} using a Lorentz pitch angle operator. In higher collisionality regimes, both models tend to yield similar scalings. In view of relative high neutral collisionality in CLM, both types of collisionality are then combined, modeling neutral collisions with the conserving Krook and Coulomb collisions with a Lorentz model. The dispersion relation is then integrated over velocity space. This combination yields results in very good accord with the available experimental data. The Ion Temperature Gradient Instability is then investigated. It is shown that anisotropy in gradient has a substantial effect on the ion temperature gradient driven mode. A gradient in the parallel temperature is needed for an instability to occur, and a gradient in the perpendicular temperature gradient further enhances the instability indirectly as long as the frequency of the mode is near ion resonance. The physical reason for this important role difference is presented. The Columbia Linear Machine is being redesigned to produce and identify the ion temperature gradient driven {eta}{sub i} mode. Using the expected parameters, the author has developed detailed predictions of the mode characteristics in the CLM. Strong multi mode instabilities are expected. As the ion parallel and perpendicular ion temperature gradients are expected to differ significantly, we differentiate between {eta}{sub i}{parallel} and {nu}{sub i}{perpendicular} and explore the physical differences between them, which leads to a scheme for stabilization of the mode.

• Research Organization: Columbia Univ., New York, NY (USA)
• OSTI ID: 5924975
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
ANISOTROPY
COLLISIONLESS PLASMA
COMPARATIVE EVALUATIONS
DESIGN
DIFFERENTIAL EQUATIONS
DISPERSION RELATIONS
EQUATIONS
FLUID MECHANICS
HYDRODYNAMICS
INSTABILITY
ION TEMPERATURE
MAGNETOHYDRODYNAMICS
MATHEMATICAL MODELS
MECHANICS
PLASMA
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
TEMPERATURE GRADIENTS
THERMONUCLEAR DEVICES
TRAPPED-PARTICLE INSTABILITY