Numerical and Analytical Study of Electron Plasma Waves in Nonthermal Vasyliunas‐Cairns Distributed Plasmas

The Poison‐Vlasov model in plasma kinetic theory is taken into account to study the propagation of electron plasma waves (or Langmuir waves) in hot, un‐magnetized Vasyliunas‐Cairns distributed plasmas (VCDPs). The longitudinal dielectric plasma response function is obtained for such nonthermal plasmas. The Landau damping rate of Langmuir waves (LWs) in nonthermal VCDP, which propagates with a phase speed greater than the effective thermal speed of the electrons, is also studied. The real and imaginary parts of the wave frequency are investigated analytically as well as numerically and a comparison between the numerical and analytical results is presented. The finding reveals that the dispersion curve and damping rate of the wave are significantly influenced by the simultaneous presence of two nonthermality parameters, that is, ′α′ and ′κ′ (spectral index) in the hybrid (Vasyliunas‐Cairns) distributed plasmas. It is discussed that results are quite distinctive from that obtained in nonthermal plasmas that have sole presence of either of the nonthermality parameters ′α′ or super‐thermality spectral index ′κ′ in Cairns or kappa distributed electron plasmas, respectively. The more realistic form of 3D and reduced 1D distribution function of VCDP has been used to analyze LWs in describing nonthermal plasmas with more energetic electron in VCDP case. Plain Language Summary In this study, the kinetic theory is used to study wave propagation and damping rate of electron plasma (or Langmuir) waves in the hybrid nonthermal (containing the nonthermality parameters α and κ simultaneously). The Poison‐Vlasov model is described for studying LWs in VCDF plasmas. The presence of both nonthermality parameters α and κ have greatly influenced both the real and imaginary part of the frequencies of Langmuir waves (LWs) in comparison with earlier published work on the sole presence of anyone of the nonthermality parameter. It has been investigated that the presence of both these parameters has a significant effect of each other on both the dispersion curve and damping rates of LWs in VCDF plasmas. It is studied that the LWs are very high‐frequency waves and their resonance occurs at higher velocities and the damping rate of the electron plasma wave increases with the increase of nonthermality parameter α and decreases with the increase of nonthermality spectral index κ. This work opens the window of opportunities to understand various modes in space plasmas especially in the so