Comment on “Interaction of Ion Cyclotron Electromagnetic Wave with Energetic Particles in the Existence of Alternating Electric Field Using Ring Distribution” by Shukla KN, Kumari J, Pandey RS

Abstract

It is already discussed categorically and in detail that for the alternating current (AC) electric field parallel to the magnetic field, the dispersion relation is too complicated and cannot be expressed through a simple expression. As they claim to use a simple relation, which cannot be applicable, the results of Shukla et al. (2022) are not reliable. Propagation of waves through a magnetized plasma having AC electric field has been discussed in detail in literature. For propagation of waves in plasma, the dielectric tensor is expressed by Summers et al. (1994), where εij are (nine) elements of dielectric tensor ε, and the wavevector is k = k⊥i ^ + kǁ k ^ , where i ^ and k ^ are, respectively, unit vector along the x-axis and z-axis of Cartesian coordinate system. Let us review our earlier work in brief. We have investigated two cases: (i) the magnetic field is perpendicular to the AC electric field (Chandra & Sharma 2020a), and (ii) the magnetic field is parallel to the AC electric field (Chandra & Sharma 2020b). Chandra & Sharma (2020a) considered the case of AC electric field E0 = E0 sin νt i ^ , and ambient magnetic field B = B0k ^ , i.e., the direction of the electric field is perpendicular to the direction of the magnetic field. For the propagation of wave parallel to the magnetic filed (i.e., along the z-axis), we have k⊥ = 0, kǁ = k, N⊥ = 0 and Nǁ = N. Therefore, ε13 = ε31 = ε23 = ε32 = 0, so that, we have