Measurements of a negative ion flux inplasma thruster tests in a vacuum chamber

Bugrova, A. I.; Desyatskov, A. V.; Морозов, А. И.; Kharchevnikov, V. K.

doi:10.1134/1.1307001

Cited by 17 publications

(23 citation statements)

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“…The theory of the anomalous transport in Hall thrusters is less developed. According to [8][9][10][11][12][13][14][15][16][17][18][19], there is a variety of mechanisms governing the electron transport in this type of thrusters: the classical collisional mechanism, the so-called near-wall conductivity [8,9], and the turbulent transport attributable to the oscillations in plasma [10][11][12][13][14][15][16][17][18][19]. The latter mechanism may also result from various types of instabilities [19][20][21][22][23][24][25][26][27][28].…”

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confidence: 99%

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

Nikitin¹,

Tomilin²,

Lovtsov³

et al. 2017

EPL

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The problem of the anomalous electron transport in crossed electric and magnetic fields in Hall plasma thrusters is investigated. Two mechanisms of turbulent transport are considered: a gradient-drift mechanism and a resistive one. A strong connection between these mechanisms and the corresponding instabilities is established. Our analysis shows that the gradient-drift transport prevails over the resistive one in the most turbulent domain of the channel. The gradient-drift transport organizes plasma in such a way to minimize the increment of the corresponding instability. This allows one to avoid explicit calculations of the fluctuation intensity while modeling transport phenomena. The modification of the dispersion relation for the gradient-drift instability, offered by Frias et al. (Phys. Plasmas, 19 (2012) 072112) to account for the current-free (vacuum) nature of a two-dimensional magnetic field, is discussed.

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confidence: 99%

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

Nikitin¹,

Tomilin²,

Lovtsov³

et al. 2017

EPL

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“…Morozov and Bugrova reported that "quick electrons" penetrate into the buffer chamber from the discharge channel and cause weak "pre-ionization" in Aton-type HETs. [29,30] Yu and Wei studied the effect of propellant pre-ionization on the current oscillation and reported that a small pre-ionization ratio would reduce the current oscillation. [31] This neutral flow pre-ionization process is a passive phenomenon and cannot be actively controlled.…”

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confidence: 99%

Study of low‐frequency oscillations in a double‐stage Hall thruster

Zhang

Ding

Han

et al. 2017

Contributions to Plasma Physics

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The characteristics of low-frequency oscillations of double-stage Hall thrusters are quite different from those of conventional single-stage Hall thrusters. In this paper, the effects of double-stage discharge on the low-frequency oscillations are experimentally investigated. The results indicate that the amplitude significantly decreases with increasing magnetic field strength and voltage during the ionization stage. Meanwhile, data analysis reveals that ionization occurs in both stages and that the transport ion current between the two stages is the key factor that affects the amplitude and main frequency of the oscillations. Two new processes, namely the ion transport and ion recombination caused by double-stage discharge, are found to be relevant to the change in the current oscillations. To summarize, the ionization stage relieves the oscillations in the acceleration stage, leading to a reduction in the amplitude of the discharge current. KEYWORDS Double-stage Hall thruster, Ion transport current, Low-frequency oscillation INTRODUCTIONIt has been proved that Hall effect thrusters (HETs) are suitable for space missions, such as orbit transfer and station keeping, owing to their high thrust density and medium specific impulse. However, future space missions require multimode Hall thrusters with flexible working conditions. [1,2] In order to control the ionization and acceleration processes independently, double-stage Hall thrusters (DSHTs) have been proposed as a new generation of thrusters for multiple working modes. [3][4][5] The ionization and acceleration processes in DSHTs are divided into two stages. Several characteristics change because of the separation of the ionization and acceleration process, especially low-frequency oscillations. [3,5] It is observed that the amplitude of the low-frequency current oscillations in a DSHT is usually small and affected by the double-stage discharge condition.[3,6] Bugrova et al. studied a DSHT, called SPT-MAG, and reported very small low-frequency current oscillations with a relative standard deviation of 1-4%.[4] They attributed the improved stability to the specially organized ionization stage, where more than 90% of the propellant was ionized. [3,4] Hirohisa et al. investigated a microwave discharge DSHT and reported that microwave injection obviously suppressed current oscillations. Propellants are ionized near the anode because of the microwave-excited surface-wave plasmas, and the ions are accelerated in the E × B field. The high-speed ion flow is considered to reduce the time lag between the gas and ion feeds, leading to a reduced current oscillation.[6] The low-frequency oscillations significantly affect the performance of HETs and have been widely studied both theoretically [7][8][9][10] and experimentally. [11,12] However, although the amplitude of the current oscillations is found to be suppressed by a double-stage discharge in the literature, there is no scientific study on the mechanism of the current suppression. With the development of DSHT technology...

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“…For the emitter material LaB 6 used in our experiments, A is about 2.9×10 5 A/(m 2 • K 2 ) and ϕ approximates 2.66 eV at T = 1600 o C. The HC which located 50 mm away from the HET exit plane, as shown in Fig. 1(b), is usually in the weak magnetic field region [11] , the potential is thus almost unchanged on the plasma bridge but drops mostly in the sheath region near the emitter surface with a distribution written as…”

Section: The Hc Electron-emission Capabilitymentioning

confidence: 97%

“…The HET used in the experiment is of model P70 which belongs to the ATON type [11,12] . Its nominal power is 1 kW and specific impulse is about 2000 s with a plume divergence less than 11 degrees and an efficiency of up to 68%.…”

Section: Experimental Apparatus and Measurementsmentioning

confidence: 99%

Effect of the Hollow Cathode Heat Power on the Performance of an Hall-Effect Thruster

Ning

et al. 2009

Plasma Sci. Technol.

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Effect of the hollow cathode heat power on the performance of a Hall-effect thruster is investigated. The variations in the Hall-effect thruster's performance (thrust, specific impulse and anode efficiency) with the hollow cathode heat power was obtained from the analysis of the experimental data. Through an analysis on the coupling relationship between the electrons emitted from the hollow cathode and the environmental plasma, it was found that the heat power would affect the electron emission of the emitter and the space potential of the coupling zone, which would lead to a change in the effective discharge voltage. The experimental data agree well with the results of calculation which can be used to explain the experimental phenomena.

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Measurements of a negative ion flux inplasma thruster tests in a vacuum chamber

Cited by 17 publications

References 1 publication

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

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

Study of low‐frequency oscillations in a double‐stage Hall thruster

Effect of the Hollow Cathode Heat Power on the Performance of an Hall-Effect Thruster

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