Accession Number:

ADA196561

Title:

Excitation of Instabilities Due to an External Field

Descriptive Note:

Final technical rept. 10 Feb 1986-31 Aug 1987,

Corporate Author:

IOWA UNIV IOWA CITY DEPT OF PHYSICS AND ASTRONOMY

Personal Author(s):

Report Date:

1988-04-18

Pagination or Media Count:

8.0

Abstract:

Simulation Study of Ion Cyclotron Like Modes in a Magnetoplasma with a Transverse Inhomogeneous Electric Field. A new mechanism can destabilize electrostatic waves in the presence of a nonuniform electric field perpendicular to the uniform ambient magnetic field. When the electric field is nonuniform, it is possible for a finite region to contain negative wave energy surrounded by regions of positive wave energy will cause the mode to grow. This gives rise to the instability. The ion-cyclotron instability is important to both space and laboratory plasma. This new mechanism is investigated for an instability by means of simulations in the presence of a nonuniform electric field perpendicular to the uniform magnetic field associated with a density gradient. A two-dimensional electrostatic code was used which retains the full dynamics of the ions in three dimensional velocity space. Electrons are treated by the guiding center approximation in the perpendicular direction while the parallel motion is treated exactly. Nonlinear phenomena such as diffusion and coalescence of vortices are investigated. In the linear stage smaller vortices are generated and larger vortices with the lower frequencies are dominant in the nonlinear stage. In the nonlinear stage ions diffuse strongly due to large-scale vortices.

Subject Categories:

  • Plasma Physics and Magnetohydrodynamics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE