Thermal effects of charged particles on parallel fast-magnetosonic/whistler instability in solar wind plasma

Abstract

Various waves and instabilities can be excited by charged particle beams in the solar wind plasma. These instabilities can provide an efficient mechanism to transfer the beam kinetic energy into electromagnetic energy. In this paper, using the kinetic theory and Lorentz transformations, we investigate the right-hand circularly polarized fast-magnetosonic/whistler wave propagating parallel to the external magnetic field and its instability in the solar wind plasma. The interaction of a proton beam with this plasma is studied by analytical and numerical methods under two scenarios: the presence and absence of thermal motions of charged particles. The results indicate that the parallel fast-magnetosonic/whistler (PFM/W) wave can be excited by the proton beam. This wave can propagate with a higher phase velocity in the presence of thermal effects. The results also show that as the beam temperature increases, the growth rate of instability first increases then decreases. However, increasing the proton temperature causes a decrease in the growth rate of instability. Additionally, we examine the impact of various parameters, such as beam density and beam velocity, on the PFM/W instability. In this study, the figures and their trends in both the analytical and numerical solutions are consistent, confirming the validity of our approach.