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

Abstract

Here, 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.

Authors:
ORCiD logo [1]; ORCiD logo [2];  [3]
  1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
  3. National Institute for Fusion Science, National Institutes of National Sciences, Gifu (Japan)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1419796
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 12; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Dodin, I. Y., Ruiz, D. E., and Kubo, S. Mode conversion in cold low-density plasma with a sheared magnetic field. United States: N. p., 2017. Web. doi:10.1063/1.5003931.
Dodin, I. Y., Ruiz, D. E., & Kubo, S. Mode conversion in cold low-density plasma with a sheared magnetic field. United States. doi:10.1063/1.5003931.
Dodin, I. Y., Ruiz, D. E., and Kubo, S. Tue . "Mode conversion in cold low-density plasma with a sheared magnetic field". United States. doi:10.1063/1.5003931. https://www.osti.gov/servlets/purl/1419796.
@article{osti_1419796,
title = {Mode conversion in cold low-density plasma with a sheared magnetic field},
author = {Dodin, I. Y. and Ruiz, D. E. and Kubo, S.},
abstractNote = {Here, 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.},
doi = {10.1063/1.5003931},
journal = {Physics of Plasmas},
number = 12,
volume = 24,
place = {United States},
year = {2017},
month = {12}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record

Figures / Tables:

FIG. 1 FIG. 1: Numerical solutions of Eq. (45) for |aO|2 for two sample profiles: (a) s(τ) = 0.02τ2 and (b) s(τ) = 40 tanh[(τ/15)3]. The envelope aO is measured in units ¯a such that | ¯a|2 is the total number of quanta, which is conserved [Eq. (36)]. The initial conditions aremore » aO(0) = 1 and aX(0) = 0, i.e., aO(0) = 0. Both solutions approach the same asymptote |aO|2= 1/2 (dashed), as predicted [Eq. (51)].« less

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