Gradient-drift and resistive mechanisms of the anomalous electron transport in Hall effect thrusters

Nikitin, V.O.; Tomilin, D. A.; Lovtsov, A. S.; Tarasov, A. G.

doi:10.1209/0295-5075/117/45001

Cited by 16 publications

(10 citation statements)

References 28 publications

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“…In this first approach we consider the simplifying assumption of a constant magnetic field in the near-anode region. Magnetic field gradients can modify the development of these instabilities 10,20,[46][47][48][49] and we leave the study of their effect for future work.…”

Section: Introductionmentioning

confidence: 99%

Micro instabilities and rotating spokes in the near-anode region of partially magnetized plasmas

Boeuf

2019

Physics of Plasmas

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Electron and ion transport in the near-anode region of a partially magnetized plasma under conditions typical of Hall thrusters or magnetron discharges is studied with fully kinetic, Particle-In-Cell Monte Carlo Collision (PIC-MCC) simulations assuming a uniform magnetic field and no ionization. We derive a simple relation that defines the magnetic field at the transition point between negative and positive sheath. For magnetic fields around or above this transition point, PIC-MCC simulations show the development of short wavelength azimuthal instabilities that cascade to longer wavelengths ("rotating spokes") as the magnetic field is increased. Both short-wavelength and large-wavelength fluctuations can coexist under some conditions. A detailed study of the fluid dispersion relation is used to analyze the PIC-MCC results. Small coherent structures can be associated with the destabilization of ion sound waves by density gradient and collisions. Longer wavelengths or rotating spokes are characteristic of the collisionless Simon-Hoh instability. The small structures are dominant for larger plasma density gradients while the larger structures correspond to smaller density gradients and larger magnetic fields. Anomalous transport associated with these instabilities can be significant, with effective collision frequencies larger than 2 × 10 7 s −1 in xenon for magnetic fields above the transition point.

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Section: Introductionmentioning

confidence: 99%

Micro instabilities and rotating spokes in the near-anode region of partially magnetized plasmas

Boeuf

2019

Physics of Plasmas

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“…5,6,11,12 The gradient drift instability has been identified experimentally and studied theoretically 13,14 in Hall plasma thrusters, also see some recent works. 15,16 The general dispersion relation for perturbations with k k ¼ 0 (k k is the component of a wavevector along the equilibrium magnetic field) has been derived in Refs. 13 and 14.…”

Section: Introductionmentioning

confidence: 99%

Effects of finite electron temperature on gradient drift instabilities in partially magnetized plasmas

et al. 2018

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The gradient-drift instabilities of partially magnetized plasmas in plasma devices with crossed electric and magnetic fields are investigated in the framework of the two-fluid model with finite electron temperature in an inhomogeneous magnetic field. The finite electron Larmor radius (FLR) effects are also included via the gyroviscosity tensor taking into account the magnetic field gradient. This model correctly describes the electron dynamics for k ? q e > 1 in the sense of Pad e approximants (here, k ? and q e are the wavenumber perpendicular to the magnetic field and the electron Larmor radius, respectively). The local dispersion relation for electrostatic plasma perturbations with the frequency in the range between the ion and electron cyclotron frequencies and propagating strictly perpendicular to the magnetic field is derived. The dispersion relation includes the effects of the equilibrium E Â B electron current, finite ion velocity, electron inertia, electron FLR, magnetic field gradients, and Debye length effects. The necessary and sufficient condition of stability is derived, and the stability boundary is found. It is shown that, in general, the electron inertia and FLR effects stabilize the short-wavelength perturbations. In some cases, such effects completely suppress the high-frequency short-wavelength modes so that only the long-wavelength low-frequency (with respect to the lower-hybrid frequency) modes remain unstable.

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“…Вопрос о проводимости электронов в разряде ХД остается до сих пор открытым: классического столкновительного механизма переноса на тяжелых частицах и величины пристеночной проводимости оказывается недостаточно для полного описания величины электронного тока. Существенное влияние оказывает так называемая аномальная проводимость, которую часто связывают с колебаниями и волнами в разряде ХД [19]. Так как расход газа при перестроении между режимами был постоянным, а магнитное поле отличалось незначительно, то можно считать, что величина классического переноса электронов была приблизительно одинакова в обоих режимах горения.…”

Section: обсуждение полученных результатовunclassified

Параметрическое Исследование Двух Устойчивых Форм Горения Разряда В Холловском Двигателе

Хмелевской¹,

Томилин²

2019

Журнал Технической Физики

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In this paper the behavior of the integral parameters of the Hall thruster (thrust, specific thrust impulse) in two stable discharge modes were experimentally investigated. This modes significantly different from each other in anode efficiency. The studies were carried out on a laboratory model of Hall thruster with the external discharge zone with the middle-line diameter equal to 77 mm. The discharge voltage was in the range of 500-900 V and a gas flow rate was from 2.0 to 5 mg/s. The most striking differences between the discharge modes are the shape of the plasma plume and the value of the discharge current at practically identical input parameters of operation (gas flow rate, discharge voltage, magnetic field). It is shown that in the entire studied range of input parameters during the transition from the optimal mode (in terms of the efficiency) to the suboptimal mode the main integral characteristics of the thruster suddenly change: the discharge current increases by 10-30% with the simultaneous relative drop of thrust by 5-15% and efficiency by 20-40%. A detailed study of the structure of the anode efficiency showed that when the transition between modes occurs the electron current efficiency (the ratio of the ion current to the discharge current) abruptly changes, that is, the electronic conductivity in the discharge channel of the thruster changes too.

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Gradient-drift and resistive mechanisms of the anomalous electron transport in Hall effect thrusters

Cited by 16 publications

References 28 publications

Micro instabilities and rotating spokes in the near-anode region of partially magnetized plasmas

Micro instabilities and rotating spokes in the near-anode region of partially magnetized plasmas

Effects of finite electron temperature on gradient drift instabilities in partially magnetized plasmas

Параметрическое Исследование Двух Устойчивых Форм Горения Разряда В Холловском Двигателе

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