Spectral analysis of Hall-effect thruster plasma oscillations based on the empirical mode decomposition

Kurzyna, J.; Mazouffre, S.; Lazurenko, A.; Albarède, L.; Bonhomme, Gérard; Makowski, Karol; Dudeck, Michel; Peradzyński, Z.

doi:10.1063/1.2145020

Cited by 54 publications

(52 citation statements)

References 27 publications

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“…1,2 The so-called transit-time instability has been experimentally identified as a longitudinal mode involving ion dynamics, with a frequency in the 100-500-kHz band. [3][4][5][6][7] Interestingly, an ion-transit instability has also been repeatedly reported in numerical simulations. [8][9][10][11] Although a candidate explanation of the transit-time mechanism was first proposed by Esipchuk in his generalization of Morozov's earlier stability study, 12,13 some issues with its mathematical treatment have been pointed out ͑cf.…”

Section: Introductionmentioning

confidence: 93%

Transit-time instability in Hall thrusters

Barral

Makowski²,

Peradzyński

et al. 2005

Physics of Plasmas

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Longitudinal waves characterized by a phase velocity of the order of the velocity of ions have been recurrently observed in Hall thruster experiments and simulations. The origin of this so-called ion transit-time instability is investigated with a simple one-dimensional fluid model of a Hall thruster discharge in which cold ions are accelerated between two electrodes within a quasineutral plasma. A short-wave asymptotics applied to linearized equations shows that plasma perturbations in such a device consist of quasineutral ion acoustic waves superimposed on a background standing wave generated by discharge current oscillations. Under adequate circumstances and, in particular, at high ionization levels, acoustic waves are amplified as they propagate, inducing strong perturbation of the ion density and velocity. Responding to the subsequent perturbation of the column resistivity, the discharge current generates a standing wave, the reflection of which sustains the generation of acoustic waves at the inlet boundary. A calculation of the frequency and growth rate of this resonance mechanism for a supersonic ion flow is proposed, which illustrates the influence of the ionization degree on their onset and the approximate scaling of the frequency with the ion transit time. Consistent with experimental reports, the traveling wave can be observed on plasma density and velocity perturbations, while the plasma potential ostensibly oscillates in phase along the discharge.

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Section: Introductionmentioning

confidence: 93%

Transit-time instability in Hall thrusters

Barral

Makowski²,

Peradzyński

et al. 2005

Physics of Plasmas

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“…This transmission line is similar in style to those previously used to study discharge oscillations in HETs. 21,22 In configuration A (IV-swept), each of the plates was effectively used as a large planar Langmuir probe. 23,24 The bias voltage was controlled using a Xantrex XPD 60-9 power supply and the plate current was measured using a Fluke 83V multimeter.…”

Section: Configuration Of Platesmentioning

confidence: 99%

Preliminary Assessment of the Role of a Conducting Vacuum Chamber in the Hall Effect Thruster Electrical Circuit

Frieman¹,

King²,

Khayms³

et al. 2014

50th AIAA/ASME/SAE/ASEE Joint Propulsion Conference

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The role of the electrically conductive vacuum chamber wall in the completion of the discharge circuit of a Hall effect thruster (HET) is experimentally investigated. The AerojetRocketdyne T-140 laboratory-model HET operating at a discharge voltage of 300 V, discharge current of 5.16 A, and anode flow rate of 5.80 mg/s serves as a representative HET test bed. The nominal facility operating pressure during thruster firings is 4.9 × 10 -6 Torr corrected for xenon. Two 0.91 m x 0.91 m square aluminum plates are placed adjacent to, but electrically isolated from, the walls of the stainless steel vacuum chamber at two locations with respect to the center of the thruster exit plane: 4.3 m axially downstream along thruster centerline and 2.3 m radially outward centered on the exit plane. The plates are configured in three distinct electrical configurations with corresponding measurements: a) electrically grounded plates with measurements of currents to ground, b) electrically isolated plates with measurements of floating voltages, and c) isolated but electrically connected plates with measurements of the current conducted between them. The measurements are all taken simultaneously with the discharge current oscillations of the thruster at a sampling frequency of 100 MHz. Measurements of the current conducted to ground in the electrically grounded configuration reveal that the axial and radial plates collect ion currents that are 13.6% and 10.7% of the discharge current, respectively; the collected current is coupled to the discharge current oscillations but is smaller in magnitude and phase-delayed. In the electrically connected plate configuration, 5.5% of the average discharge current is observed to flow from the axial plate to the radial plate driven by a floating voltage difference of 7.6 V; this current is uncorrelated in time with the discharge current oscillations. These results indicate that the vacuum chamber conducts current and is a recombination site for a significant number of plume ions during HET operation. NomenclatureI = current, A 2 Pb = vacuum chamber base pressure, Torr Pc = corrected vacuum chamber background pressure, Torr Pi = indicated vacuum chamber background pressure, Torr V = voltage, V Vc-g = cathode-to-ground voltage, V Vd = discharge voltage, V Vp = plasma potential with respect to ground, V Vpa = axial plate voltage with respect to ground, V Vpr = radial plate voltage with respect to ground, V ΔV = acceleration voltage, V ΔVcath = cathode coupling voltage, V

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“…Some are in the 10-100 kHz range and have other similarities; among them are the breathing mode, rotating spoke mode, and azimuthal drift magnetosonic waves. 36,[56][57][58][59] Slow instabilities have also been found in the output current of plasma guides (macroparticle filters) for vacuum arc plasmas (cf. Figure 13 of Ref.…”

Section: Fig 6 (Color Online)mentioning

confidence: 99%