scholarly journals Radial distribution of electrons rotation moment in hall effect and plasma-ion thrusters

2021 ◽  
pp. 28-34
Author(s):  
Zongshuai Guo
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Cross Section ◽  
Radial Distribution ◽  
Electric Propulsion ◽  
Mirror Reflection ◽  
Radial Magnetic Field ◽  
Ion Thrusters ◽  
Wall Conductivity ◽  
The Cross

The subject matter of the article is the radial distribution of electrons movement parameters inside electric propulsion thrusters with closed electrons drift. The radial magnetic field in Hall effect thrusters is the limits the axial flow of electrons because of interaction with azimuth electron current. In turn, this azimuth current exists as a result of rivalry between the attempt of the magnetic field to transform electrons current completely closed one and the loss of electrons rotation moment in collisions. Similar processes take place in the ionization chamber of plasma-ion thrusters with the radial magnetic field. The attempts to estimate electrons parameters through only collisions with ions and atoms inside volume have given the value of axial electrons current much lower than really being. This phenomenon is called anomalous electrons conductivity, which was tried to be explained as a consequence of various effects including "near-the-wall-conductivity", which was explained as a result of non-mirror reflection of electrons from the Langmuir layer near the walls of the thruster channel. The disadvantage of this name is the fact that the reflection of the electron occurs before reaching the surface from the potential barrier at the plasma boundary with any environment: the wall, but also with the environment vacuum. The potential distribution in the Langmuir layer is non-stationary and inhomogeneous due to the presence of so-called plasma oscillations. The definition of "conductivity" is just as unfortunate in this name, because the collisions are always not a factor of conductivity, but on the contrary – of resistance. The goal is to solve the task of electrons rotation moment distribution in the thruster channel. The methods used are the formulation of the kinetic equation for electrons distribution function over the velocities, radius, and projections of the coordinates of the instantaneous center of cyclotron rotation; solution of this equation and finding with its use the distribution of the gas-dynamic parameters of electrons along the cross-section of the channel. Conclusions. A mathematical model of electrons rotation moment dynamics is proposed, which allows using plasma-dynamics equations to analyze its distribution along the cross-section of thruster channel and to estimate the effect of "near-the-wall-conductivity" using appropriate boundary conditions.

scholarly journals КВАЗІОДНОВИМІРНА МАТЕМАТИЧНА МОДЕЛЬ ПРОЦЕСІВ В ХОЛЛІВСЬКОМУ ТА ПЛАЗМОВО-ІОННОМУ ДВИГУНІ

2021 ◽  
pp. 41-54
Author(s):  
A. V. Loyan ◽  
S. Yu. Nesterenko ◽  
Guo Zongshuai ◽  
Huang Zhihao
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Thermodynamic Equilibrium ◽  
Ionization Chamber ◽  
Gas Dynamics ◽  
Electric Propulsion ◽  
Mirror Reflection ◽  
Radial Magnetic Field ◽  
Plasma Dynamics ◽  
One Dimensional

Plasma-ion thrusters with a radial magnetic field in ionization chamber and Hall effect thrusters are electrostatic electric propulsion thrusters with closed electron drift. Axial symmetry in the dynamics of the components of propellant in these thrusters allows to write the equations of plasma-dynamics for electrons, ions and neutral atoms in two-dimensional axial-radial form. Attempts to reduce the equations to simpler one-dimensional form by simply removing the components with radius differentiation lead to the loss in the description of important effects, responsible for values of thruster performance. At the same time, a significant disadvantage of gas dynamics equation set is its fundamental openness – the correspondence between the number of unknown variables and equations is achieved approximately basing on some assumptions. In traditional form of gas dynamics, such closeness is made under the assumption of thermodynamic equilibrium with velocity distribution functions of components close to Maxwell one, which is the limit result of collisions. The use of such approximation to plasma components dynamics in electric propulsion thrusters is impossible due to the rarefaction of the substance in them. A mathematical model of two-component plasma-dynamics is represented in stationary form to describe the processes in the Hall effect thruster channel and the ionization chamber of plasma-ion thruster with radial magnetic field. Due to the impossibility of using the method of local thermodynamic equilibrium to describe the rarefied substance in electric propulsion thruster, a more advanced form of equations is used. A more reliable means of approximate closure of the set of equations is proposed in the description of the rarified gas. An approach to the description of the specifics of electrons energy transfer from the plasma to the walls of the channel, as well as the non-mirror reflection of electrons from the potential barrier within the Langmuir layer is shown. A method of averaging the parameters over the cross section of the channel is proposed, which allows to convert the equation into a quasi-one-dimensional form with the preservation of charge, momentum and energy losses on the channel walls.

Magnetic-field dependence of the cross section formJmixing in2P1/2Cs and Rb atoms

1994 ◽  
Vol 49 (6) ◽  
pp. 4540-4548 ◽  
Author(s):  
W. Kedzierski ◽  
Ju Gao ◽  
W. E. Baylis ◽  
L. Krause
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Field Dependence ◽  
Magnetic Field Dependence ◽  
The Cross

Performance investigation of a high-temperature and power Hall-effect electric propulsion

2019 ◽  
Vol 85 (6) ◽  
Author(s):  
Lai Li ◽  
Xi Lu ◽  
Wei Wang ◽  
Guiping Zhu ◽  
Hulin Huang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Temperature ◽  
Hall Effect ◽  
Lorentz Force ◽  
Electric Propulsion ◽  
Uniform Magnetic Field ◽  
Computational Analysis ◽  
External Potential ◽  
Gas Temperature ◽  
The Magnetic Field

This paper discusses a detailed computational analysis that illustrated the influences of the magnetic field and external potential on the performance of a high-temperature Hall-effect electric thruster. Uniform and non-uniform magnetic field configurations were examined. The Lorentz force in the $x$ direction, acting on the plasma, was shown to substantially enhance the flow velocity in the non-uniform magnetic field, which indicated that the non-uniform magnetic field was more suitable for Hall-effect electromagnetic acceleration. The static temperature increased with the external potential, especially near the region of cathode. This increment in gas temperature, together with the effect of the Lorentz force, results in the enhancement of the velocity at the front and back of the cathode. However, the Mach number and gas density decreased due to static temperature increases caused by the conversion of more electric power into internal energy. The thrust increased eventually with the increase of the average exit velocity.

scholarly journals Rotating magnetic field effect on convection and its stability in a horizontal cylinder subjected to a longitudinal temperature gradient

2010 ◽  
Vol 664 ◽  
pp. 108-137 ◽  
Author(s):  
D. V. LYUBIMOV ◽  
A. V. BURNYSHEVA ◽  
H. BENHADID ◽  
T. P. LYUBIMOVA ◽  
D. HENRY
Keyword(s):  
Magnetic Field ◽  
Temperature Gradient ◽  
Prandtl Number ◽  
Cross Section ◽  
Rotating Magnetic Field ◽  
Shear Mode ◽  
Convective Flows ◽  
Longitudinal Temperature Gradient ◽  
Longitudinal Temperature ◽  
The Cross

A rotating magnetic field (RMF) is used in crystal growth applications during the solidification process in order to improve the crystal quality. Its influence on the convective flows in molten metals and on their stability is studied here in the case of a horizontal infinite cylindrical channel subjected to a longitudinal temperature gradient. The steady convective flows, which correspond to the usual longitudinal counterflow structure, with four vortices in the cross-section for non-zero Prandtl number, Pr, are modified by the RMF (parametrized by the magnetic Taylor number Tam). For zero Prandtl number, the flow in the cross-section corresponds to circular streamlines and the longitudinal flow structure is moved in the direction of the magnetic field rotation, with a decrease in its intensity and an asymptotic variation as 1/Tam. For non-zero Prandtl numbers, depending on the respective values of Tam on one side and Prandtl and Grashof numbers on the other side, different structures ranging from the circular streamlines with transport by rotation of the longitudinal velocity and the temperature field, to the more usual counterflow structure almost insensitive to the RMF with four cross-section vortices, can be obtained. The decrease in the flow intensity with increasing Tam is also delayed for non-zero Pr, but the same asymptotic limit is eventually reached. The stability analysis of these convective flows for Tam = 0 shows a steep increase of the thresholds around Pr = Prt,0 ≈ 3 × 10−4, corresponding to the transition between the usual counterflow shear mode and a new sidewall shear mode. This transition is still present with an RMF, but it occurs for smaller Pr values as Tam is increased. Strong stabilizing effects of the rotating magnetic field are found for Pr < Prt,0, particularly for Pr = 0 where an exponential increase of the threshold with Tam is found. For Pr > Prt,0 (i.e. in the domain where the sidewall instability is dominant), in contrast, the stabilization by the RMF is weak.

scholarly journals Collision of a Positron with the Capture of an Electron from Lithium and the Effect of a Magnetic Field on the Particles Balance

Chemosensors ◽  
2021 ◽  
Vol 9 (3) ◽  
pp. 45
Author(s):  
Elena V. Orlenko ◽  
Alexandr V. Evstafev ◽  
Fedor E. Orlenko
Keyword(s):  
Magnetic Field ◽  
Strong Magnetic Field ◽  
Cross Section ◽  
Dynamic Equilibrium ◽  
Mass Effect ◽  
Alpha Particles ◽  
Exchange Effects ◽  
The Cross ◽  
Living Tissues ◽  
Comparison Of The Results

The processes of scattering slow positrons with the possible formation of positronium play an important role in the diagnosis of both composite materials, including semiconductor materials, and for the analysis of images obtained by positron tomography of living tissues. In this paper, we consider the processes of scattering positrons with the capture of an electron and the formation of positronium. When calculating the cross-section for the capture reaction, exchange effects caused by the rearrangement of electrons between colliding particles are taken into account. Comparison of the results of calculating the cross-section with a similar problem of electron capture by a proton showed that the mass effect is important in such a collision process. The loss of an electron by a lithium atom is more effective when it collides with a positron than with a proton or alpha particles. The dynamic equilibrium of the formation of positronium in the presence of a strong magnetic field is considered. It is shown that a strong magnetic field during tomography investigation shifts the dynamic equilibrium to the positronium concentration followed by positron annihilation with radiation of three gamma-quants.

scholarly journals Production Cross Sections of Axion in a Static Electromagnetic Field

2013 ◽  
Vol 23 (1) ◽  
pp. 21
Author(s):  
Dang Van Soa ◽  
Tran Dinh Tham
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Field ◽  
Electric Field ◽  
Total Cross Section ◽  
Strong Magnetic Field ◽  
Cross Section ◽  
Cross Sections ◽  
Feynman Diagram ◽  
Production Cross ◽  
The Cross

Photon - axion conversions in staticelectromagnetic fields of the size \(a\times b \times c\) areconsidered in detail by the Feynman diagram methods. Thedifferential cross sections are presented and the numericalevaluations of the total cross section are given. Our result showsthat the conversion cross-sections in the electric field are quitesmall, while in the strong magnetic field, the cross-sections are much enhanced, which can be measurable in current experiments.

scholarly journals Theoretical constraints on the cross-tail width of bursty bulk flows

2013 ◽  
Vol 31 (12) ◽  
pp. 2179-2192 ◽  
Author(s):  
C. X. Chen
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Plasma Sheet ◽  
Unstable Mode ◽  
Force Balance ◽  
Larmor Radius ◽  
The Cross ◽  
Fast Flow ◽  
Flow Burst ◽  
Bursty Bulk Flows

Abstract. The characteristic cross-tail width of bursty bulk flows (BBFs) in earth's plasma sheet was investigated at two stages of its life, one at its onset, the other when it is fully developed. Equilibrium domains with gradient of magnetic field are constructed. Interchange instability analysis of such domains yields the most unstable mode with the half wave length comparable with the observed cross-tail width of a flow burst and the inverse of growth rate comparable with its duration. The thickness of the plasma sheet for the most unstable mode is also comparable to the width of BBFs in the north–south direction. We found that viscosity, the dimension of the unstable domain, the thickness of the plasma sheet and gradient of the magnetic field together determine the most unstable mode. The ion Larmor radius plays an important role in viscosity as half effective mean free path. For a fully developed flow, however, velocity-caused pressure difference between the leading and trailing sides of a flow burst also plays a role. The equatorial cross section of flow is reshaped and its cross-tail width is changed as well. Representing the surrounding medium with empirical magnetic field and plasma models, the force balance of the fast flow is analyzed. The cross-section area of flow burst is estimated to be one to several square earth radii, and the cross-tail width of fast flow is estimated to be 1 to 3 earth radii, which is consistent with observations of BBFs.

scholarly journals THE REACTION 4He(γ, p)3H, CAUSED BY POLARIZED PHOTONS IN THE GIANT RESONANCE RANGE

2019 ◽  
pp. 21-25
Author(s):  
A.A. Peretiatko ◽  
R.T. Murtazin ◽  
A.F. Khodyachikh
Keyword(s):  
Magnetic Field ◽  
Cross Section ◽  
Diamond Crystal ◽  
Giant Resonance ◽  
Knock Out ◽  
Chamber Method ◽  
The Asymmetry ◽  
The Cross ◽  
Polarized Photons

The reaction of 4He(γ, p)3H in the range of giant resonance was studied by a streamer chamber method in a magnetic field irradiated with polarized photons obtained by plane channeling of electrons by a diamond crystal. The angular and energetic dependences of the asymmetry of the cross section have been measured. The results are explained by the mechanism of direct knock out of nucleons.

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