Ion beam excitation of ion-cyclotron waves and ion heating in plasmas with drifting electrons

Hauck, J. P.; Böhmer, H.; Rynn, N.; Benford, Gregory

doi:10.1017/s0022377800023229

Cited by 21 publications

(16 citation statements)

References 8 publications

(6 reference statements)

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“…The beam is given perpendicular energy by positioning the beam source off the cylindrical axis in an end region of converging magnetic field where the obliqueness of the beam to the magnetic field decreases with decreasing radial position. Hauck et al 62 investigate experimentally the excitation of ion-cyclotron waves by a purely axial ion beam by placing the beam source on the cylindrical axis.…”

Section: B Experimental Resultsmentioning

confidence: 99%

Inhomogeneous magnetic-field-aligned ion flow measured in a Q machine

et al. 2002

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Radial profiles of ion flow vd(r) are measured with laser-induced fluorescence for cases in which the flow direction is parallel (vd>0) and/or antiparallel (vd<0) to the equilibrium magnetic field. Experiments are conducted in the barium-ion plasma of a double-ended Q machine. In cases where the ionizers associated with the two ends are not biased relative to each other, two distinct, counterstreaming ion-beam populations are evident. The insertion of blocking electrodes introduces inhomogeneity into the density profiles of the ion populations without effecting the homogeneity of the radial profile of each population’s drift velocity. In cases where the two ionizers are biased relative to each other, a single ion population exists. Variation in the radial profile of the ion population’s parallel drift velocity vd is produced such that (dvd/dr) can be negative or positive with magnitudes 0–70% of the ion gyrofrequency ωci. These results are discussed in the context of beam-driven and velocity-shear-driven instabilities. Laboratory and space measurements of sheared parallel flow and counterstreaming ion beams are compared.

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Section: B Experimental Resultsmentioning

confidence: 99%

Inhomogeneous magnetic-field-aligned ion flow measured in a Q machine

et al. 2002

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“…Two factors may mitigate the preceding calculations; electron drift may reduce Landau damping, or the beams may be filamented. The effect of electron drift on ion beams has been noted by Hauck et al [1978], who showed that when the electron drift velocity is roughly equal and opposite to the ion beam velocity, the growth rate for the production of EHC waves by the ion beam is greatly enhanced. From the magnetometer data of Figure 9 we calculate a downward electron drift velocity of 1.25 x 102 km/s, while the ion beam velocity is upward at about 4 x 102 km/s.…”

Section: During This Period the •By Component Increases In The Positivementioning

confidence: 99%

“…At least two possible sources exist: electron drift in field-aligned currents and ion beams along the magnetic field, and evidence of both processes exist in the data. Furthermore, the two processes may interact by electron drift relaxation of the instability requirements for an ion beam [Hauck et al, 1978]. Of course, the two processes have quite different implications; the electron drift source converts the energy associated with field-aligned current to energetic ions, while the ion beam source produces strong pitch angle scattering in the ion beam.…”

Section: Production Of Ehc Wavesmentioning

confidence: 99%

Simultaneous observations of energetic (keV) upstreaming and electrostatic hydrogen cyclotron waves

Kintner¹,

Kelley²,

Sharp³

et al. 1979

J. Geophys. Res.

267

139

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A comparative study of upstreaming energetic ions in the kilovolt energy range and electrostatic hydrogen cyclotron (EHC) waves has been made using the ion mass spectrometer and plasma wave receiver data sets for the first 1200 orbits of the S3‐3 spacecraft. The upstreaming energetic ions and EHC waves are found to coincide in over 90% of the events studied. In addition, both EHC waves and upstreaming ions with energies greater than 500 eV exhibit a lower border in their altitude distribution near 5000 km. The nearly exact correlation suggests either that the upstreaming ions are producing the EHC waves or that the EHC waves are heating the ions. One example of EHC waves and upstreaming energetic ions is analyzed to test the two hypotheses. Evidence that EHC waves are heating ions is presented in the form of conic ion distributions which some theories predict are the consequence of this process. Perpendicular ion heating to at least 6 keV is found to coincide with EHC waves. Evidence that the upstreaming ions are the source of free energy for the EHC waves is presented in the form of an ion distribution function with ∂f/∂ν > 0. However, the stability of that ion distribution function is considered and found to be stable unless other conditions such as filamentation or electron drift are invoked. There also exists the possibility that the source of free energy for EHC waves is drifting thermal electrons. For the one example studied the drifting electron process is consistent with data from the S3‐3 magnetometer. However, it is inconsistent with the S3‐3 electron spectrometer which indicates that the current is carried by keV electrons, not thermal electrons. Consequently, the source of free energy for EHC waves is not yet unambiguously determined.

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“…Since ω/k z ν d > 1 for the higher-frequency eigenmode and ω/k z ν d < 0 for the lowerfrequency eigenmode, inverse Landau damping is not destabilizing the waves. The only other laboratory observation of spontaneously excited, electrostatic ion-cyclotron waves propagating antiparallel to the electron drift direction is the ion-beam-driven waves reported by Hauck et al (1978), but in this case the wave frequency normalized to the ion gyrofrequency does not upshift with experimental parameters. The amplitude of these non-resonant eigenmodes is not sensitive to the relative bias between the hot-plate the diskelectrode, as is the amplitude of the dissipative eigenmodes, implying that, as expected for predominantly reactive eigenmodes, they do not tap the free energy available in the parallel electron drift.…”

Section: Discussionmentioning

confidence: 82%

Resonant-to-nonresonant transition in electrostatic ion-cyclotron wave phase velocity

Carroll

Koepke

Zintl

et al. 2003

Nonlin. Processes Geophys.

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Abstract. Because of the implications for plasmas in the laboratory and in space, attention has been drawn to inhomogeneous energy-density driven (IEDD) waves that are sustained by velocity-shear-induced inhomogeneity in crossfield plasma flow. These waves have a frequency ω r in the lab frame within an order of magnitude of the ion gyrofrequency ω ci , propagate nearly perpendicular to the magnetic field (k z /k ⊥ 1), and can be Landau resonant (0 < ω 1 /k z < ν d ) with a parallel drifting electron population (drift speed ν d ), where subscripts 1 and r indicate frequency in the frame of flowing ions and in the lab frame, respectively, and k z is the parallel component of the wavevector. A transition in phase velocity from 0 < ω 1 /k z < ν d to 0 > ω 1 /k z > ν d for a pair of IEDD eigenmodes is observed as the degree of inhomogeneity in the transverse E × B flow is increased in a magnetized plasma column. For weaker velocity shear, both eigenmodes are dissipative, i.e. in Landau resonance, with k z ν d > 0. For stronger shear, both eigenmodes become reactive, with one's wavevector component k z remaining parallel, but with ω 1 /k z > ν d , and the other's wavevector component k z becoming anti-parallel, so that 0 > ω 1 /k z . For both eigenmodes, the transition (1) involves a small frequency shift and (2) does not involve a sign change in the wave energy density, which is proportional to ω r ω 1 , both of which are previously unrecognized aspects of inhomogeneous energydensity driven waves.

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Ion beam excitation of ion-cyclotron waves and ion heating in plasmas with drifting electrons

Cited by 21 publications

References 8 publications

Inhomogeneous magnetic-field-aligned ion flow measured in a Q machine

Inhomogeneous magnetic-field-aligned ion flow measured in a Q machine

Simultaneous observations of energetic (keV) upstreaming and electrostatic hydrogen cyclotron waves

Resonant-to-nonresonant transition in electrostatic ion-cyclotron wave phase velocity

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