Destruction of Cyclotron Resonances in Weakly Collisional, Inhomogeneous Plasmas.
Abstract
It is shown, both analytically and numerically, that cyclotron resonances can be destroyed in dense (omega sub rho > Omega, where omega sub rho is the plasma frequency and Omega is the cyclotron frequency), weakly collisional, inhomogeneous plasmas when (nu/Omega) k-squared (r sub L) squared somewhat > 1, where nu is the collision frequency and sub L is the mean Larmor radius. The theory is based upon a model Fokker-Planck equation. It is found that the particles make a transition from magnetized to unmagnetized behavior. This is an important result since it indicates that the ion- and electron-cyclotron-drift instabilities transform into their unmagnetized counterparts, the lower-hybrid-drift instability and the ion acoustic instability, respectively. The ion-cyclotron-drift instability (or drift-cyclotron instability) is examined in detail and is found to become the lower-hybrid-drift-instability in the region of maximum growth when (sq.rt.(m sub e/m sub i) omega/Omega sub i somewhat > nu sub ii/Omega sub i somewhat > m sub e/m sub i for T sub e approximately equal T sub i plasmas. The first inequality is required to overcome electron viscous damping, while the second allows the ions to become unmagnetized. Applications to the equatorial F region of the ionosphere and the Tandem Mirror Experiment (TMX) are discussed. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Apr 10, 1979
- Accession Number
- ADA067827
Entities
People
- Joseph D. Huba
- Sidney L. Ossakow
Organizations
- United States Naval Research Laboratory