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

Journal Article · Tue Jan 15 04:00:00 EST 2008 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.2827518· OSTI ID:21069943

Yang, Zhang; Heidbrink, W W; Boehmer, H; McWilliams, R; Chen, Guangye; Breizman, B N; Vincena, S; Carter, T; Leneman, D; Gekelman, W; Pribyl, P; Brugman, B ^[1]

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1. Department of Physics and Astronomy, University of California, Irvine, California 92697 (United States)

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 Alfven spectra. Shear Alfven waves (SAW) are launched by antennas inserted in the LAPD plasma and diagnosed by B-dot probes at many axial locations. Alfven 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.

• OSTI ID: 21069943
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 1 Vol. 15; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
ALFVEN WAVES
AMPLITUDES
ANTENNAS
COMPUTERIZED SIMULATION
ELECTRON-ION COLLISIONS
ELECTRONS
LANDAU DAMPING
MAGNETIC MIRRORS
MODULATION
PERIODICITY
PLASMA
PLASMA DIAGNOSTICS
PLASMA SIMULATION
S CODES
SHEAR
TWO-DIMENSIONAL CALCULATIONS
WAVE PROPAGATION