Spectral gap of shear Alfv́n waves in a periodic array of magnetic mirrors

Yang Zhang; W. W. Heidbrink; H. Boehmer; R. McWilliams; Guangye Chen; B. N. Breizman; S. Vincena; T. Carter; D. Leneman; W. Gekelman; P. Pribyl; B. Brugman

doi:10.1063/1.2827518

Spectral gap of shear Alfv́n waves in a periodic array of magnetic mirrors

Yang Zhang, W. W. Heidbrink, H. Boehmer, R. McWilliams, Guangye Chen, B. N. Breizman, S. Vincena, T. Carter, D. Leneman, W. Gekelman, P. Pribyl, B. Brugman

Research output: Contribution to journal › Article › peer-review

29 Scopus citations

Abstract

A multiple magnetic mirror array is formed at the Large Plasma Device (LAPD) [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)] to study axial periodicity-influenced Alfv́n spectra. Shear Alfv́n waves (SAW) are launched by antennas inserted in the LAPD plasma and diagnosed by B-dot probes at many axial locations. Alfv́n wave spectral gaps and continua are formed similar to wave propagation in other periodic media due to the Bragg effect. The measured width of the propagation gap increases with the modulation amplitude as predicted by the solutions to Mathieu's equation. A two-dimensional finite-difference code modeling SAW in a mirror array configuration shows similar spectral features. Machine end-reflection conditions and damping mechanisms including electron-ion Coulomb collision and electron Landau damping are important for simulation.

Original language	English
Article number	012103
Journal	Physics of Plasmas
Volume	15
Issue number	1
DOIs	https://doi.org/10.1063/1.2827518
State	Published - 2008
Externally published	Yes

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title = "Spectral gap of shear Alf{\'v}n waves in a periodic array of magnetic mirrors",

abstract = "A multiple magnetic mirror array is formed at the Large Plasma Device (LAPD) [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)] to study axial periodicity-influenced Alf{\'v}n spectra. Shear Alf{\'v}n waves (SAW) are launched by antennas inserted in the LAPD plasma and diagnosed by B-dot probes at many axial locations. Alf{\'v}n wave spectral gaps and continua are formed similar to wave propagation in other periodic media due to the Bragg effect. The measured width of the propagation gap increases with the modulation amplitude as predicted by the solutions to Mathieu's equation. A two-dimensional finite-difference code modeling SAW in a mirror array configuration shows similar spectral features. Machine end-reflection conditions and damping mechanisms including electron-ion Coulomb collision and electron Landau damping are important for simulation.",

author = "Yang Zhang and Heidbrink, {W. W.} and H. Boehmer and R. McWilliams and Guangye Chen and Breizman, {B. N.} and S. Vincena and T. Carter and D. Leneman and W. Gekelman and P. Pribyl and B. Brugman",

year = "2008",

doi = "10.1063/1.2827518",

language = "English",

volume = "15",

journal = "Physics of Plasmas",

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publisher = "American Institute of Physics",

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TY - JOUR

T1 - Spectral gap of shear Alfv́n waves in a periodic array of magnetic mirrors

AU - Zhang, Yang

AU - Heidbrink, W. W.

AU - Boehmer, H.

AU - McWilliams, R.

AU - Chen, Guangye

AU - Breizman, B. N.

AU - Vincena, S.

AU - Carter, T.

AU - Leneman, D.

AU - Gekelman, W.

AU - Pribyl, P.

AU - Brugman, B.

PY - 2008

Y1 - 2008

N2 - A multiple magnetic mirror array is formed at the Large Plasma Device (LAPD) [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)] to study axial periodicity-influenced Alfv́n spectra. Shear Alfv́n waves (SAW) are launched by antennas inserted in the LAPD plasma and diagnosed by B-dot probes at many axial locations. Alfv́n wave spectral gaps and continua are formed similar to wave propagation in other periodic media due to the Bragg effect. The measured width of the propagation gap increases with the modulation amplitude as predicted by the solutions to Mathieu's equation. A two-dimensional finite-difference code modeling SAW in a mirror array configuration shows similar spectral features. Machine end-reflection conditions and damping mechanisms including electron-ion Coulomb collision and electron Landau damping are important for simulation.

AB - A multiple magnetic mirror array is formed at the Large Plasma Device (LAPD) [W. Gekelman, H. Pfister, Z. Lucky, J. Bamber, D. Leneman, and J. Maggs, Rev. Sci. Instrum. 62, 2875 (1991)] to study axial periodicity-influenced Alfv́n spectra. Shear Alfv́n waves (SAW) are launched by antennas inserted in the LAPD plasma and diagnosed by B-dot probes at many axial locations. Alfv́n wave spectral gaps and continua are formed similar to wave propagation in other periodic media due to the Bragg effect. The measured width of the propagation gap increases with the modulation amplitude as predicted by the solutions to Mathieu's equation. A two-dimensional finite-difference code modeling SAW in a mirror array configuration shows similar spectral features. Machine end-reflection conditions and damping mechanisms including electron-ion Coulomb collision and electron Landau damping are important for simulation.

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DO - 10.1063/1.2827518

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VL - 15

JO - Physics of Plasmas

JF - Physics of Plasmas

IS - 1

M1 - 012103

ER -

Spectral gap of shear Alfv́n waves in a periodic array of magnetic mirrors

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