Radial electron density distribution in plasma flow in a coaxial hall accelerator

Anoshko, I. A.; Ermachenko, V. S.; Rolin, M. N.; Sevast'yanenko, V. G.; Sandrigailo, L. E.

doi:10.1007/bf00870828

Cited by 3 publications

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“…The kinetic simulations studied by Sydorenko [11] and Smirnov [12] have shown that the high-energy tail of the electron velocity distribution function (EVDF) in the thruster is almost exhausted due to the collision between the electrons and the wall; meanwhile, experimental studies [13,14] have proved that the electron energy distribution function in the thruster obviously deviates from the Maxwellian distribution due to the strong interaction between the electrons and the wall. Maxwellian distribution approximation has its limitations for systems such as long-range Coulomb interactions and non-thermodynamic equilibrium plasmas.…”

Section: Introductionmentioning

confidence: 99%

Study on the characteristics of non-Maxwellian magnetized sheath in Hall thruster acceleration region

Chen¹,

An²,

Sun³

et al. 2022

Plasma Sci. Technol.

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The secondary electron emission and inclined magnetic field are typical features at the channel wall of Hall thruster acceleration region, and the characteristics of the magnetized sheath have significant effect on the radial potential distribution, ion radial acceleration and wall erosion. In this paper, the magnetohydrodynamics model is used to study the characteristics of the magnetized sheath with secondary electron emission in acceleration region of Hall thruster. The electrons are assumed to obey non-extensive distribution, the ions and secondary electrons are magnetized. Based on the Sagdeev potential, the modified Bohm criterion is derived, and the influences of the non-extensive parameters and magnetic field on the acceleration region sheath structure and parameters are discussed. Results show that, with the decrease of the parameter q, the high-energy electron leads to an increase of the potential drop in the sheath, and the sheath thickness expands accordingly, the kinetic energy rises when ions reach the wall, which can aggravate the wall erosion. Increasing the magnetic field inclination angle in the AR of the Hall thruster, the Lorenz force along the x direction acting as a resistance decelerating ions is larger which can reduce the wall erosion, while the strength of magnetic field in the AR has little effect on Bohm criterion and wall potential. The propellant type also has a certain effect on the values of wall potential and secondary electron number density and sheath thickness.

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Section: Introductionmentioning

confidence: 99%

Study on the characteristics of non-Maxwellian magnetized sheath in Hall thruster acceleration region

Chen¹,

An²,

Sun³

et al. 2022

Plasma Sci. Technol.

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“…After testing the line intensities for self-absorption, we selected the NII and NIII nitrogen ion lines, which satisfy conditions (1) and (2). Their characteristics are given in Table 1.…”

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Determination of electron temperature based on a semicoronal model in Hall accelerator plasma flows

2007

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We present the results of a spectroscopic study of a nonequilibrium plasma in a Hall accelerator, in particular for such an important parameter as the electron temperature. For the studied conditions, we used the semicoronal equilibrium model, which relates the intensity ratios for two successive ionization steps for the same element.Introduction. are devoted to measurement of the temperature and concentration of electrons in the plasma of a Hall accelerator. The measurements were made spectroscopically assuming partial local thermodynamic equilibrium (partial LTE). In this model, concentrations of free electrons are assumed for which collisional processes dominate starting only from some k-th excitation state, while radiative processes predominate for lower levels. The electron temperature was determined from the Saha-Boltzmann equation, assuming a singly-ionized plasma. This assumption is quite well grounded, since under the studied conditions (P = 1.2⋅10 3 Pa, G = 10 g/sec, J = 2200-3000 A, and B = 1 T), the NI and NII nitrogen lines completely dominated while the contribution of NIII ions was estimated previously. The free electron concentration was measured from the broadening of the hydrogen H β line, the width of which is practically independent of temperature and the equilibrium state. The measured concentration, depending on the jet parameters, was N e = 10 15 to 10 16 cm -3 , temperature T e = (2-3)⋅10 4 K.The Experiment and Measurement Procedure. We studied a nonequilibrium plasma for the following Hall accelerator operating conditions: pressure in the vacuum chamber, P = 1.05⋅10 3 Pa; working gas flowrate, G = 4 g/sec (2.5 g/sec for air, 1.5 g/sec for nitrogen); discharge currents, J = 1300 A, 1600 A, and 2000 A; magnetic field induction, B = 2.2 T. The emission spectra of the jet were recorded using an autocollimated UF-90 camera, combined with a flat diffraction grating, in a cross section 40 mm away from the edge of the nozzle. The dispersion of the instrument was 0.65 nm/mm. The pictures were taken through a glass window in the vacuum chamber, which was located 480 mm away from the jet axis. The jet diameter was ≈40 mm, and the length varied from 150 mm to 200 mm depending on the operating conditions. Analysis of the emission spectra shows that in the plasma jet, the NII and NIII nitrogen ion lines dominate, where the NIII lines are at a lower height than the NII lines (concentrated near the axis). The H β hydrogen line is emitted uniformly over the entire height of the spectrum and is broadened (but not so strongly as for a flowrate of 10 g/sec); superimposed on this line is one of the NIII nitrogen ion lines, while there is practically no continuous spectrum. It does not seem possible to measure the concentration from the broadening of the hydrogen line. The indicated circumstances suggest a decrease in the free electron concentration in the plasma of the Hall accelerator compared with the operating conditions described in [3]. Indirect confirmation of such a hypothesis comes from the lack of n...

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Calculation of the velocity of a plasma flow in the nozzle exit section of a coaxial-electrode Hall accelerator

Anoshko

Ermachenko

2006

J Eng Phys Thermophys

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Radial electron density distribution in plasma flow in a coaxial hall accelerator

Cited by 3 publications

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Study on the characteristics of non-Maxwellian magnetized sheath in Hall thruster acceleration region

Study on the characteristics of non-Maxwellian magnetized sheath in Hall thruster acceleration region

Determination of electron temperature based on a semicoronal model in Hall accelerator plasma flows

Calculation of the velocity of a plasma flow in the nozzle exit section of a coaxial-electrode Hall accelerator

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