Mode conversion in cold low-density plasma with a sheared magnetic field

I. Y. Dodin; D. E. Ruiz; S. Kubo

doi:10.1063/1.5003931

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arXiv · 1709.02841

Mode conversion in cold low-density plasma with a sheared magnetic field

I. Y. Dodin·D. E. Ruiz·S. Kubo

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Abstract

A theory is proposed that describes mutual conversion of two electromagnetic modes in cold low-density plasma, specifically, in the high-frequency limit where the ion response is negligible. In contrast to the classic (Landau--Zener-type) theory of mode conversion, the region of resonant coupling in low-density plasma is not necessarily narrow, so the coupling matrix cannot be approximated with its first-order Taylor expansion; also, the initial conditions are set up differently. For the case of strong magnetic shear, a simple method is identified for preparing a two-mode wave such that it transforms into a single-mode wave upon entering high-density plasma. The theory can be used for reduced modeling of wave-power input in fusion plasmas. In particular, applications are envisioned in stellarator research, where the mutual conversion of two electromagnetic modes near the plasma edge is a known issue.

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I. Y. Dodin, D. E. Ruiz, S. Kubo. 2017-09-08. Mode conversion in cold low-density plasma with a sheared magnetic field. https://doi.org/10.1063/1.5003931

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