Nonlinear saturation of the dissipative trapped-ion mode by mode coupling

Technical Report · Tue Jun 01 04:00:00 EDT 1976

DOI:https://doi.org/10.2172/7189685· OSTI ID:7189685

Cohen, B I; Krommes, J A; Tang, W M; Rosenbluth, N

The nonlinear saturation of the dissipative trapped-ion mode is analyzed. The basic mechanism considered is the process whereby energy in long wave-length unstable modes is nonlinearly coupled via E x B convection to short wavelength modes stabilized by Landau damping due to both circulating and trapped ions. In the usual limit of the mode frequency, small relative to the effective electron collision frequency, a one-dimensional nonlinear partial differential equation for the potential can be derived, as first shown by LaQuey, Mahajan, Tang, and Rutherford. The stability and accessibility of the possible equilibria for this equation are examined in detail, both analytically and numerically. The equilibrium emphasized by LaQuey et al. is shown to be unstable. However, a class of nonlinear saturated states which are stable to linear perturbations is found. Included in the analysis are the effects of both ion collisions and dispersion due to finite ion banana-width effects. Cross-field transport is estimated and the scaling of the results is considered for tokamak parameters (specifically those for the Princeton Large Torus). It is concluded that the anomalous cross-field transport can be much lower than the estimate of Kadomtsev and Pogutse, for relevant parameters.

• Research Organization: Princeton Univ., N.J. (USA). Plasma Physics Lab.
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• OSTI ID: 7189685
• Report Number(s): MATT-1259
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
700107* -- Fusion Energy-- Plasma Research-- Instabilities
CLOSED PLASMA DEVICES
COUPLING
DAMPING
INSTABILITY
LANDAU DAMPING
NONLINEAR PROBLEMS
ONE-DIMENSIONAL CALCULATIONS
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
PLASMA WAVES
THERMONUCLEAR DEVICES
TOKAMAK DEVICES
TRAPPED-PARTICLE INSTABILITY