A wave-particle interaction model for tail ion acceleration in reversed field pinch plasmas

In the reversed field pinch plasmas produced by the reversed field experime nt (RFX), neutral particle measurements reveal the presence in the radial d irection of a small population of non-thermal energetic ions (E = 10(3) eV to 8 x 10(3) eV). In this work supra-thermal electrons at the plasma edge a re considered to be the free-energy source for the ion acceleration. Fast e lectrons, moving in the same direction of the main magnetic field, excite a n omega similar to omega(pi) electrostatic wave which gives energy to the i ons which are accelerated in the direction perpendicular to the local equil ibrium magnetic field. The theoretical predictions for the neutral particle fluxes are in agreement with the experimental measurements. Moreover, a co rrelation between the experimental fast-ion and fast-electron energy densit ies has been found.