Beam-driven three-dimensional electromagnetic strong turbulence

Journal Article · Wed Aug 15 04:00:00 EDT 2012 · Physics of Plasmas

DOI:https://doi.org/10.1063/1.4740058· OSTI ID:22086011

Graham, D B; Robinson, P A; Cairns, Iver H ^[1]

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1. School of Physics, University of Sydney, New South Wales 2006 (Australia)

Large scale beam-driven electromagnetic strong turbulence is investigated by numerically solving the three-dimensional electromagnetic Zakharov equations, where turbulence is driven at nonzero wavenumbers k. For electron thermal speeds v{sub e}/c Greater-Than-Or-Equivalent-To 0.1, a significant fraction of driven Langmuir waves undergo electromagnetic decay into electromagnetic waves and ion-acoustic waves so that transverse waves contribute significantly to the total energy density. It is shown that as v{sub e}/c increases, the wavenumber and energy density of transverse waves produced increase. For v{sub e}/c Less-Than-Or-Equivalent-To 0.1, beam-driven turbulence is approximately electrostatic. An approximately periodic cycle is observed, similar to previous two-dimensional electrostatic simulations, in which Langmuir waves are driven to larger mean energy densities until a series of backscatters occurs, shifting the Langmuir waves out of resonance with the driver and decreasing the wavenumber of the Langmuir waves. A low-k condensate results from which wave packets form and collapse, decreasing the mean energy density. Averaging over many of these periods, the statistical properties are calculated and the scaling behavior of the mean energy density is shown to agree well with the electrostatic two-component model prediction. When driven at nonzero k the scaling behavior is shown to depend weakly on v{sub e}/c, in contrast to when strong turbulence is driven at k = 0, where the scalings depend more strongly on v{sub e}/c.

• OSTI ID: 22086011
• Journal Information: Physics of Plasmas, Journal Name: Physics of Plasmas Journal Issue: 8 Vol. 19; ISSN PHPAEN; ISSN 1070-664X
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BEAMS
ELECTROMAGNETIC RADIATION
ELECTRONS
ENERGY DENSITY
ION ACOUSTIC WAVES
LANGMUIR FREQUENCY
PLASMA SIMULATION
SCALING
THREE-DIMENSIONAL CALCULATIONS
TURBULENCE
TWO-DIMENSIONAL CALCULATIONS
WAVE PACKETS