Kinetic Formulation of Transport of Charged Particles Interacting With Electromagnetic Waves in Magnetized Plasmas
Abstract
There have been a number of studies on the dynamics of charged particles in the presence of electromagnetic waves in a magnetized plasma. These studies have noted that the motion of particles can be regular or chaotic depending on various wave parameters, and energies of the interacting particles. The dynamical phase space turns out to be a mixture of regular and chaotic motion -- and the chaotic motion is not necessarily Markovian, i.e., akin to the random walk dynamics. There exist long time correlations in the interaction process so that the dynamics encompasses interesting and complex physics. Naturally occurring or remotely excited electromagnetic waves are ubiquitous in space plasmas as well as in laboratory and astrophysical plasmas. The interaction of particles with these waves is an equally ubiquitous phenomenon. A description of the evolution of the particle distribution function has to properly account for the particle dynamics. Previous formulations of the kinetic equation have assumed that the particle dynamics is completely Markovian. From the dynamics of particles in the presence of waves, we know that this assumption is not valid. We have recently formulated the kinetic equation for the evolution of a particle distribution function in which the particle motion is perturbed by electromagnetic waves in a magnetized plasma [1]. We do not make any Markovian assumption and the full dynamics of the particles is determined from the Lorentz equation. The derivation makes use of the mathematical tools that have been developed for Hamiltonian systems. We derive the kinetic equation using the Lie perturbation technique. The diffusion operator describing the evolution of the distribution function is time dependent and valid for a dynamical phase space that is a mix of correlated regular orbits and decorrelated chaotic orbits. This is in contrast to standard kinetic equations in which the diffusion operator is independent of time and singular. The singular behavior is due to the Markovian assumption and appears in the form of a Dirac delta function which does not lend itself to any sensible numerical implementation. The diffusion operator that we derive includes resonant and non-resonant momentum space diffusion, and non-resonant spatial transport of particles. The kinetic equation applies to space plasmas and, in general, to magnetized plasmas where the magnetic equilibrium is known. It is in a form that is suitable for inclusion in numerical codes. Work supported by DoE grants DE-FG02-99ER-54521 and DE-FG02-91ER-54109, and by Association EURATOM, Hellenic Republic. [1] Y. Kominis, A.K. Ram, and K. Hizanidis, Phys. Plasmas 15, 122501 (2008).
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2009
- Bibcode:
- 2009AGUFMSM53A1355R
- Keywords:
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- 2483 IONOSPHERE / Wave/particle interactions;
- 2799 MAGNETOSPHERIC PHYSICS / General or miscellaneous;
- 7867 SPACE PLASMA PHYSICS / Wave/particle interactions