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Dispersive Alfven waves (DAWs) offer, an alternative to magneticreconnection, opportunity to accelerate solar flare particles. We study theeffect of DAW polarisation, L-, R-, circular and elliptical, in differentregimes inertial and kinetic on the efficiency of particle acceleration. We use2.5D PIC simulations to study how particles are accelerated when DAW, triggeredby a solar flare, propagates in transversely inhomogeneous plasma that mimicssolar coronal loop. (i) In inertial regime, fraction of accelerated electrons(along the magnetic field), in density gradient regions is ~20% by the timewhen DAW develops 3 wavelengths and is increasing to ~30% by the time DAWdevelops 13 wavelengths. In all considered cases ions are heated in transverseto the magnetic field direction and fraction of the heated particles is ~35%.(ii) The case of R-circular, L- and R- elliptical polarisation DAWs, with theelectric field in the non-ignorable transverse direction exceeding severaltimes that of in the ignorable direction, produce more pronounced parallelelectron beams and transverse ion beams in the ignorable direction. In theinertial regime such polarisations yield the fraction of accelerated electrons~20%. In the kinetic regime this increases to ~35%. (iii) The parallel electricfield that is generated in the density inhomogeneity regions is independent ofm_i/m_e and exceeds the Dreicer value by 8 orders of magnitude. (iv) Electronbeam velocity has the phase velocity of the DAW. Thus electron acceleration isvia Landau damping of DAWs. For the Alfven speeds of 0.3c the consideredmechanism can accelerate electrons to energies circa 20 keV. (v) The increaseof mass ratio from m_i/m_e=16 to 73.44 increases the fraction of acceleratedelectrons from 20% to 30-35% (depending on DAW polarisation). For the massratio m_i/m_e=1836 the fraction of accelerated electrons would be >35%.

physics of plasmas

Particle acceleration by circularly and elliptically polarised  dispersive Alfven waves in a transversely inhomogeneous plasma in the  inertial and kinetic regimes