Excitation of the modified Simon–Hoh instability in an electron beam produced plasma

Sakawa, Y.; Joshi, C.; Kaw, P. K.; Chen, F. F.; Jain, V. K.

doi:10.1063/1.860803

Cited by 55 publications

(70 citation statements)

References 11 publications

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“…Such waves can occur at frequencies higher than the ion cyclotron frequency 34,35,48 and can be driven unstable by radial electric fields 49 or electron collisions parallel to the background magnetic field. 50,51 In order to examine the possibility of the plasma conditions near the H6MS cathode giving rise to such an oscillation, we have used Ref. 52 as a guideline to develop a simple two-fluid model in cylindrical coordinates for the potential amplitudẽ / of a bounded, azimuthally propagating electrostatic mode in a collisional plasma (Appendix)…”

Section: B High Frequency Mode (70-90 Khz)mentioning

confidence: 99%

Plasma oscillations in a 6-kW magnetically shielded Hall thruster

Jorns

Hofer

2014

Physics of Plasmas

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A time-resolved laser induced fluorescence study on the ion velocity distribution function in a Hall thruster after a fast current disruption Phys. Plasmas 16, 043504 (2009); 10.1063/1.3112704 Internal plasma potential measurements of a Hall thruster using xenon and krypton propellant Phys. Plasmas 13, 093502 (2006); 10.1063/1.2335820 Spectral analysis of Hall-effect thruster plasma oscillations based on the empirical mode decompositionPlasma oscillations from 0-100 kHz in a 6-kW magnetically shielded Hall thruster are experimentally characterized with a high-speed, optical camera. Two modes are identified at 7-12 kHz and 70-90 kHz. The low frequency mode is found to be azimuthally uniform across the thruster face, while the high frequency oscillation is peaked close to the centerline-mounted cathode with an m ¼ 1 azimuthal dependence. An analysis of these results in the context of wavebased theory suggests that the low frequency wave is the breathing mode oscillation, while the higher frequency mode is gradient-driven. The effect of these oscillations on thruster operation is examined through an analysis of thruster discharge current and a comparison with published observations from an unshielded variant of the thruster. Most notably, it is found that although the oscillation spectra of the two thrusters are different, they exhibit nearly identical steady-state behavior. V C 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4879819] PHYSICS OF PLASMAS 21, 053512 (2014) This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditions. Downloaded to IP: 193.0.65.67 On: Tue, 25 Nov 2014 14:28:57 FIG. 3. (a) Phase of the mode at 7-12 kHz as a function of normalized position. The reference point ðr 0 ; h 0 Þ employed to generate this plot is located in the channel. (b) Phase of the mode at 70-90 kHz. The reference point ðr 0 ; h 0 Þ for this plot is located off-axis at r 0 ¼ 0.05r c .

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Section: B High Frequency Mode (70-90 Khz)mentioning

confidence: 99%

Plasma oscillations in a 6-kW magnetically shielded Hall thruster

Jorns

Hofer

2014

Physics of Plasmas

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“…Modified Simon Hoh instability can occur in collision less plasma due to substantial difference in the Larmor radii of ions and electrons, with a real frequency intermediate to the electron and ion cyclotron frequencies. 43 However, observed frequencies are much smaller than ion and electron cyclotron frequencies. The theoretical growth rate calculations for SH and MSH instabilities, 44 indicate that the growth rate decreases with increase in B T and there is no threshold on B T for the excitation of these modes.…”

Section: B Fluctuations At 440 G and 660 G-turbulent Regimementioning

confidence: 97%

Coherent to turbulence transition, enhanced flow and confinement in a simple toroidal plasma

et al. 2012

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In a simple toroidal plasma, self consistent poloidal flow generation at different toroidal fields is observed. On changing the magnitude of toroidal field, transition occurs in the nature of fluctuation from highly coherent modes at low magnetic field to a turbulent broadband spectrum at high field accompanied by significant improvement in the confinement. Interestingly, though the coherence is reduced with the increasing field, the fluctuation driven poloidal flux remains comparable. The observed increase in the densities on high field side with the increase in magnetic field is simultaneously accompanied by the enhanced net poloidal flow. The present work demonstrates that in a toroidal compressible plasma, an intimate relationship exists between the fluctuations, self consistently generated flows and enhanced confinement. V C 2012 American Institute of Physics.

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“…The local linear dispersion relation for low-frequency RT mode [16,17], which has been identified in our system, may be written as follows: …”

Section: Theoretical Aspectsmentioning

confidence: 99%

Low-frequency fluctuations in a pure toroidal magnetized plasma

2009

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A magnetized, low-β plasma in pure toroidal configuration is formed and extensively studied with ion mass as control parameter. Xenon, krypton and argon plasmas are formed at a fixed toroidal magnetic field of 0.024 T, with a peak density of ∼10 11 cm −3 , ∼4 × 10 10 cm −3 and ∼2 × 10 10 cm −3 respectively. The experimental investigation of time-averaged plasma parameter reveals that their profiles remain insensitive to ion mass and suggests that saturated slab equilibrium is obtained. Low-frequency (LF) coherent fluctuations (ω < ω ci) are observed and identified as flute modes. Here ωci represents ion cyclotron frequency. Our results indicate that these modes get reduced with ion mass. The frequency of the fluctuating mode decreases with increase in the ion mass. Further, an attempt has been made to discuss the theory of flute modes to understand the relevance of some of our experimental observations.

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Excitation of the modified Simon–Hoh instability in an electron beam produced plasma

Cited by 55 publications

References 11 publications

Plasma oscillations in a 6-kW magnetically shielded Hall thruster

Plasma oscillations in a 6-kW magnetically shielded Hall thruster

Coherent to turbulence transition, enhanced flow and confinement in a simple toroidal plasma

Low-frequency fluctuations in a pure toroidal magnetized plasma

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