Compression of whistler waves in a plasma with a nonstationary magnetic field |
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Authors: | M E Gushchin S V Korobkov A V Kostrov A V Strikovsky |
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Institution: | (1) Institute of Applied Physics, Russian Academy of Sciences, Nizhni Novgorod, 603950, Russia |
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Abstract: | We present the results of our experiments in which the propagation of whistler waves in a plasma with a nonstationary magnetic-field perturbation (B=B0+δB(t), δB/B0 ≤ 5%) was investigated. The parametric and dispersive phenomena in a variable magnetic field were studied on the unique Krot plasma bench (the plasma column was 4 m in length and 1.5 m in diameter). A periodic field perturbation is shown to lead to an amplitude-frequency modulation of the whistler wave and to fragmentation of the signal into separate frequency-modulated wavepackets followed by their compression. The formation and compression of pulses is attributable to strong whistler group-velocity dispersion near the electron cyclotron frequency (ω ≤ ωH). The results can be used to interpret the spectral shapes of the signals received from the Earth’s magnetosphere and ionosphere in the electron and ion whistler frequency ranges. |
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