Magnetic field perturbations correlated with large amplitude lower-hybrid waves in a high-voltage linear plasma discharge

Abstract

Theoretical description of experiments on excitation of magnetic field perturbations correlated with large amplitude lower-hybrid (LH) wave bursts in a high-voltage linear plasma discharge is presented. It is shown that the magnetic field perturbations, which are excited in the experiments mostly in the paramagnetic sense, are associated with the development of the magneto-modulational processes. The theoretical results are compared with the experimental data using the following parameters: the values of the magnitude of the magnetic field perturbations; the direction of the vector of the magnetic field perturbation; the correlation between the magnetic field perturbations and the electron density perturbations. It is shown that for LH waves propagating in one plane theoretical predictions are in a good agreement with the experimental results. Keywords:high-current linear plasma discharge, lower-hybrid wave, modulational interaction, magnetic field perturbation, magneto-modulational processThe experiments in a high-current linear plasma discharge carried out at the Nihon University [1] have shown the possibility of the excitation of magnetic field perturbations related to intense lower-hybrid turbulence. The value of the magnitude of the perturbations is |δB| ≈ 10 G and |δB|/|B 0 | ≈ 0.01, where B 0 is the unperturbed magnetic field. The characteristic features of the observations are: 1) the magnetic field perturbations are excited in the experiments mostly in the paramagnetic sense; 2) there is a correlation between the magnetic field perturbations and the electron density perturbations; 3) the power spectrum of the associated electric field fluctuations shows widely broadened profile and has multiple peaks around the lower-hybrid (LH) frequency.All the results show that the excitation of the magnetic field perturbations can be associated with the development of the magneto-modulational processes [2]. We check this assumption. Equation for magneto-modulational perturbationsThe theoretical investigation of the magneto-modulational processes with the participation of LH waves has been performed for tokamak plasmas [3,4]. The conditions of the

Whistler radiation in plasmas with cylindrical magnetic field irregularities

“…Effects induced by the presence of plasma density enhancements or depletions (or combination thereof) were studied in detail both experimentally [18][19][20] and theoretically [21][22][23][24]. Over the past decade, the magnetic field perturbations caused by intense whistler and lower hybrid waves gave rise to substantial interest [25][26][27]. They may appear due to specific nonlinear phenomena, like the inverse Faraday effect which can occur in the presence of largeamplitude elliptically polarized waves in a plasma [28].…”