Numerical Study of RF-Plugging of Plasma Particles in a Line-Cusp Magnetic Field

Abstract

Particle orbits in a line-cusp magnetic field in the presence of electrostatic rf-field localized to the maximum magnetic field region are studied numerically under the initial conditions that the particles start from the cusp center along the straight magnetic field. Results show that 1) when the rf-frequency ω is greater than the maximum cylotron frequency ω c0 and the electric field strength E is less than a critical value E c , the particles are either unconfined or reflected adiabatically depending on whether the initial energy is greater or smaller than the maximum ponderomotive potential \(\varPhi_{\text{m}}\) of the rf-field; 2) when ω c0 E c , nonadiabatic reflection occurs in the energy region just below \(\varPhi_{\text{m}}\); and 3) when ω<ω c0 there always exist three regimes of unconfinement, nonadiabatic reflection and adiabatic reflection depending on the initial energy. The value of E c is determined by the condition for occurrence of the Doppler-shifted cyclotron resonance.