A numerical solution for the time evolution of a periodic acceleration field in a plasma system

Abstract

Energetic particle beams have numerous uses in many areas of research and in the industry. They are usually generated by allowing particle streams to accelerate under the influence of strong electromagnetic (EM) fields over some distance. In this acceleration process, there is a tradeoff between the size of the system, the strength of the EM fields and the energy of the beams. To attain the desired beam energy, one has to either increase the length over which the particles are accelerated or the strength of the EM fields. The practical limits of these two parameters in a small laboratory or industrial factory setup demands for more elegant mechanisms for obtaining energetic particle beams.
Similar problems were also faced by conventional accelerator scientists and plasma was suggested as a suitable medium for particle acceleration. Plasma is ideal because very strong transient electric fields (with energies in the order of a few GeV) can be generated within it by simply inducing the appropriate periodic disturbances to the uniform number density of a certain particle specie. Methods for inducing this disturbance rely on either direct introduction of particle streams or optical excitation. The quasineutrality of plasma also shields the environment from the strong electric fields that would otherwise tear apart the systems supporting structures.
We plan to utilize similar mechanisms to accelerate ion beams. This will present unique difficulties, because the main hindrance to a large scale application of plasma as an acceleration medium are the nonlinear effects of the introduction of such disturbances. Also the practical considerations for the construction of high density ion sources requires the use of a complex multi-specie (about five dominant) plasma, further compounding the non-linear effects. But the development of the technique may be worth pursuing because it may allow the development of compact, yet powerful beam sources.