Nonlinear dynamics of electrons accelerated by resonant fields in nonuniform plasmas
Abstract
A numerical and analytical study is presented of the nonlinear phasespace trajectories of particles accelerated by resonant electric fields in a nonuniform plasma. The fields are represented by a driven Airy pattern characteristic of resonant excitation, and thus the results have relevance to several topics of current interest. The acceleration processes can be classified into three regimes depending upon the initial energy of the particles. The first type is a diffusive interaction which occurs for highenergy particles. The second type is slowing down due to temporary trapping inside potential wells having a spatially decreasing phase velocity. The third type is a phaseindependent acceleration of slow particles. The comparison velocity used to classify these regimes is ωL/(k_{D}L/√3)^{2/3}, where ω is the resonant frequency, L the gradient scale length, and k_{D} the Debye wave number. Simple analytic expressions are found that explain the basic features of numerical test particle orbits and illuminate the existence of the three categories of interaction.
 Publication:

Physics of Fluids B
 Pub Date:
 December 1990
 DOI:
 10.1063/1.859224
 Bibcode:
 1990PhFlB...2.3134M
 Keywords:

 Electron Acceleration;
 Nonuniform Plasmas;
 Plasma Dynamics;
 Plasma Resonance;
 PlasmaElectromagnetic Interaction;
 PlasmaParticle Interactions;
 Energetic Particles;
 High Energy Interactions;
 Particle Acceleration;
 Particle Trajectories;
 Plasma Physics