Linear and nonlinear theory of trapped-particle instabilities

Conference · Wed Sep 01 00:00:00 EDT 1976

OSTI ID:7241509

Tang, W. M.; Adam, J. C.; Cohen, B. I.

This paper analyzes several important features of trapped-particle instabilities. For trapped-electron modes, the complete two-dimensional (2D) spatial structure, including the effects of magnetic shear, is numerically calculated within the framework of a differential formulation for long radial wavelength modes. Growth rates obtained for representative cases correlate reasonably well with the usual one-dimensional (1D) estimates of shear stabilization. However, the spatial structure of the mode differs markedly; e.g., it typically extends over several mode-rational surfaces. At the shorter wavelengths, where the maximum growth rates of the modes typically occur, it is necessary to introduce an integral equation formulation for calculating the radial dependence. Growth rates from this 2D analysis are significantly smaller than 1D estimates, and the poloidal mode structure exhibits a pronounced localization at the magnetic field minimum. Specific collisional mechanisms affecting the linear stability of these modes are also studied. Collisional scattering of low energy electrons can reduce the nonadiabatic trapped-electron response, and collisional broadening can strongly modify the resonant response of the untrapped electrons. The saturation of the usual form of the dissipative trapped-ion instability by mode coupling is studied analytically and numerically.

• Research Organization: Princeton Univ., N.J. (USA). Plasma Physics Lab.
• DOE Contract Number: E(11-1)-3073
• OSTI ID: 7241509
• Report Number(s): PPPL-1279; CONF-761012-19; TRN: 77-003014
• Resource Relation: Conference: 6. international conference on plasma physics and controlled nuclear fusion research, Berchtesgaden, F.R. Germany, 6 Oct 1976
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
TRAPPED-PARTICLE INSTABILITY
NONLINEAR PROBLEMS
MAGNETIC FIELD CONFIGURATIONS
SHEAR
TRAPPED ELECTRONS
TWO-DIMENSIONAL CALCULATIONS
ELECTRONS
ELEMENTARY PARTICLES
FERMIONS
INSTABILITY
LEPTONS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
700107* - Fusion Energy- Plasma Research- Instabilities