Verification of Polarization Reversal of Electromagnetic Waves with Electron Cyclotron Frequency Controlling Plasma-Structure Formation

Abstract

Selectively launched electromagnetic waves with left- and right-handed polarizations for m = 0, +1, and -1 modes are investigated in terms of polarization reversal around an electron cyclotron resonance (ECR) region in inhomogeneously magnetized plasmas, where m is an azimuthal mode number. It is observed for the first time that a left-handed polarized wave for m = 0 mode is absorbed near the ECR point as a result of the polarization reversal in the axial direction. Dispersion analysis in bounded plasmas can explain this quantitatively. For m = +1 and -1 modes, on the other hand, polarization reversal occurs along the radial axis, i.e., wave polarization for m = +1 mode is right-handed (left-handed for m = -1 mode) around the central area and left-handed (right-handed for m = -1 mode) around the peripheral area of the cross section of the plasma column. Furthermore, we investigate plasma-potential structures formed by ECR of high-power m = +1 and -1 waves and, for the first time, demonstrate control of the plasma-potential structure by changing the azimuthal mode, i.e., a positive potential hill is formed near the ECR point around the central and peripheral areas for m = +1 and -1 modes, respectively.