Laboratory observation of Alfvén resonance

Mitchell, Chris; Vincena, S.; Maggs, J. E.; Gekelman, Walter

doi:10.1029/2000gl012165

Cited by 20 publications

(20 citation statements)

References 14 publications

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“…3b displays a pronounced cutoff at the He ion cyclotron frequency as well as distinct peaks below. These peaks are similar to those observed in previous experiments on shear Alfvén resonances that were launched using an antenna driven by a current pulse [19]. in Fig.…”

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confidence: 89%

Production of Alfvén Waves by a Rapidly Expanding Dense Plasma

et al. 2001

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The expansion of a dense (initially, n(lpp)/n(0)>>1) laser-produced plasma into an ambient magnetized plasma ( n(0) = 2 x 10(12) cm(-3)) capable of supporting Alfvén waves has been studied. The interaction results in the production of shear Alfvén waves as well as large density perturbations (Delta n/n(0) approximately 0.3) associated with the moving dense plasma. The waves propagate away from the target and are observed to become plasma-column resonances. Spatial patterns of the wave magnetic fields are measured and are used to estimate the coupling efficiency of the laser energy and the kinetic energy of the dense plasma into wave energy.

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confidence: 89%

Production of Alfvén Waves by a Rapidly Expanding Dense Plasma

et al. 2001

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“…Monochromatic signals or pulses can be applied. It is well known 36,37 that in cylindrical plasmas with a vacuum (or low density) gap between the main plasma and the vacuum vessel, there is the possibility of exciting radial eigenmodes of the fast (compressional) Alfv en wave; however, previous experiments in LAPD using similar antennas in plasmas with either a single ion species, [38][39][40] or two ion species, 30,31 have not observed such modes to be excited in the explored range of frequencies.…”

Section: Methodsmentioning

confidence: 97%

Investigation of an ion-ion hybrid Alfvén wave resonator

et al. 2013

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A theoretical and experimental investigation is made of a wave resonator based on the concept of wave reflection along the confinement magnetic field at a spatial location where the wave frequency matches the local value of the ion-ion hybrid frequency. Such a situation can be realized by shear Alfv en waves in a magnetized plasma with two ion species because this mode has zero parallel group velocity and experiences a cut-off at the ion-ion hybrid frequency. Since the ion-ion hybrid frequency is proportional to the magnetic field, it is expected that a magnetic well configuration in a two-ion plasma can result in an Alfv en wave resonator. Such a concept has been proposed in various space plasma studies and could have relevance to mirror and tokamak fusion devices. This study demonstrates such a resonator in a controlled laboratory experiment using a H þ -He þ mixture. The resonator response is investigated by launching monochromatic waves and impulses from a magnetic loop antenna. The observed frequency spectra are found to agree with predictions of a theoretical model of trapped eigenmodes. V C 2013 American Institute of Physics.

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“…At the frequency modified Alfvén resonance, wave energy transfers from the compressional wave to the shear Alfvén wave/ion cyclotron wave analogous to the MHD case [e.g., Karney et al , 1979; Winglee , 1982; Kim and Lee , 2003]. The finite f / f cH effect on ULF waves becomes important at the magnetosheath [ Belmont and Rezeau , 2001], the magnetopause [ Rezeau et al , 1989], and laboratory plasma experiments [e.g., Tsushima et al , 1982; Mitchell et al , 2001].…”

Section: Introductionmentioning

confidence: 99%

Resonant absorption of ULF waves at Mercury's magnetosphere

Kim

Lee

2008

J. Geophys. Res.

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[1] Ultra low frequency (ULF) waves, which are assumed to be standing waves on the field, are observed by the Mariner 10 spacecraft at Mercury. These waves are oscillating at 38% of the proton gyrofrequency. It is well known that heavy ions, such as Na + , are abundant in Mercury's magnetosphere. Because the presence of different ion species has an influence on plasma dispersion characteristics near the ion gyrofrequencies, magnetospheric eigenoscillations observed at Mercury with frequency in the gyrofrequency range require a multi-fluid treatment for the plasma. Thus ULF waves at Mercury may have a distinct difference from typical ULF oscillations at Earth, which are often described in terms of magnetohydrodynamics. By adopting a multi-fluid numerical wave model, we examine how magnetic eigenoscillations occur in Mercury's magnetosphere. Because protons and sodium ions are the main constituents at Mercury, we assume an electron-proton-sodium plasma in our model. Our results show: (1) the observed ULF waves are likely compressional waves rather than standing oscillations such as field line resonances (FLRs), (2) FLRs at Mercury are expected to occur when the ion-ion hybrid and/or Alfvén resonance conditions are satisfied, (3) the magnetic field of FLRs at Mercury's magnetosphere oscillates linearly in the east-west (azimuthal) meridian when the frequency is located between two ion gyrofrequencies, and (4) the resonance frequency enables us to estimate the local heavy ion concentration ratio.

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Laboratory observation of Alfvén resonance

Abstract: Abstract.We

Cited by 20 publications

References 14 publications

Production of Alfvén Waves by a Rapidly Expanding Dense Plasma

Production of Alfvén Waves by a Rapidly Expanding Dense Plasma

Investigation of an ion-ion hybrid Alfvén wave resonator

Resonant absorption of ULF waves at Mercury's magnetosphere

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