Kinetic model of three component, weakly ionized, collisional plasma with a beam of neutral particles

It is well-known that neutral beam injection is one of the fundamental fusion plasma heating methods. In general, a particle accelerator is used to create fast ion beams (the particle energies are on the order of 100 keV); the ion beam is then passed through a neutral gas region, where the ions neutralize via charge-exchange reactions with the neutral gas. The neutralized beam is then injected into a magnetically confined plasma. Of course, the neutral atoms are unaffected (not confined) by the magnetic field, but ionize as they penetrate into the plasma. Then the high-energy ions transfer fraction of their energy to the plasma particles in repeated collisions, and heat the plasma [1–6]. In this paper we develop a kinetic model of three component, weakly ionized, collisional plasma with a beam of neutral particles. We employ a kinetic equation for the charged particles of α sort in the weakly ionized plasma with the Batnagar-Gross-Krook (BGK) model collisional term. Similar model has been developed previously by others [7]. In this book authors do not take into account possibility of existence of regular velocity of the neutral particles [7]. In the light of the possible relevance of our model for the heating of plasma by neutral beam injection, we set out with the aim to generalize results of Ref. [7] by allowing neutral particles to have regular velocity and seek for possible novelties brought about by this effect. Indeed, the dispersion relations for linear perturbations obtained in this paper differ substantially from those of Ref. [7]. In section II we formulate our model and obtain general dispersion relation. In section III we analyze various limiting cases of the dispersion relation and discuss the results.