CN104239704A - Quantitative analysis method for potential barrier between space plasma bodies and plasma bodies generated through electric propulsion - Google Patents

Abstract

The invention discloses a quantitative analysis method for potential barrier between space plasma bodies and plasma bodies generated through electric propulsion. The quantitative analysis method is applicable to the analysis of the action process of the space plasma bodies and the plasma bodies generated through the GEO orbit satellite electric propulsion. The diffusion process of the plasma bodies generated through the electric propulsion is compared with the diffusion process of current carriers in a semiconductor, and a diffusion model for the space plasma bodies and the plasma bodies generated through the electric propulsion is built according to the semiconductor current carrier diffusion theory; the quantitative expression relationship between the potential barrier intensity v between the space plasma bodies and the plasma bodies generated through the electric propulsion, and the parameters of space environment plasma bodies and the parameters of the plasma bodies generated through the electric propulsion is deduced by using the diffusion model; during the analysis, the parameters of the space plasma bodies of a GEO rail and the parameters of the plasma bodies generated through the electric propulsion are determined; according to the two kinds of determined plasma body parameters, the parameters are substituted into the quantitative expression relationship to determine the potential barrier intensity between the space plasma bodies and the plasma bodies generated through the electric propulsion.

Description

Space plasma and electric propulsion produce potential barrier quantitative analysis method between plasma

Technical field

The present invention relates to the quantitative analysis method of potential barrier between a kind of space plasma and electric propulsion generation plasma, be applicable to the computational analysis that the electric propulsion of GEO (geostationary orbit) orbiter produces plasma and space plasma mechanism.

Background technology

Along with the development of China's aerospace industry, a new generation of China high capacity communications satellite will adopt electric propulsion technology in a large number, electric propulsion is a kind of high specific impulse, long-life, high efficiency spacemarching, significantly can reduce the carrying amount of propellant, significantly improve payload ratio, extend the lifetime of satellite, therefore along with China is to the growth of satellite long-life high-performance demand, the use of electric propulsion technology will become a kind of inexorable trend.

Telstar runs on GEO track, this orbit space plasma characteristics is mainly high energy worst density, and low-yield, highdensity plasma during thruster operation on orbit, can be produced, to have an effect with the naturally occurring high-temperature in space, low density plasmas, cause the charge and discharge process of satellite more complicated, cause between the loss of the satellite high pressure sun power of battery, parts and produce the harm such as short-circuit current and structure potential drifting, thus affect satellite safe operation in-orbit.

The mechanism that thruster produces plasma and space plasma is comparatively complicated, document " Zhang Tianping; the particular surroundings of electric propulsion spacecraft and impact thereof; " Spacecraft Environment Engineering " " article describes the particular surroundings such as plasma and electromagnetic field that electric propulsion system produces around spacecraft, discuss these particular surroundingss to have an impact effect to each subsystem of spacecraft or parts, but document does not consider that thruster produces the effect of plasma and space plasma, and be qualitative analysis, cannot directly for spacecraft shield design provides guidance.

The interactively that thruster produces plasma and space plasma is such: it is fast that thruster produces electrons spread speed in plasma, ion diffuse speed is slow, thus produce an electron-ion layer, form a shielding potential barrier, the ion suppressed in space plasma is arrived spacecraft surface by this potential barrier, affects the charge and discharge process of whole spacecraft.Therefore, potential barrier is the important parameter that reflection thruster produces plasma and space plasma mechanism, when being greater than the ion energy in space plasma when potential barrier, ion cannot pass through potential barrier and arrive spacecraft, otherwise, ion will reduce energy through potential barrier, thus carry out effective evaluation to spacecraft charging and discharging effects.

Therefore, the size quantitatively calculating potential barrier is prerequisite and the basis of carrying out above-mentioned discharge and recharge evaluation, but, do not have quantitative computer memory plasma and electric propulsion to produce the scheme of potential barrier between plasma in prior art.

Summary of the invention

In view of this, the invention provides the quantitative analysis method of potential barrier between a kind of space plasma and electric propulsion generation plasma, be applicable to the analysis that the electric propulsion of GEO orbiter produces plasma and space plasma mechanism.

This quantitative analysis method comprises:

Step one, diffusion process electric propulsion being produced plasma are analogous to the diffusion process of charge carrier in semiconductor, set up the diffusion model of space plasma and electric propulsion generation plasma according to semiconductor carriers diffusion theory, the current density comprising electronics in space plasma calculates model J _ethe current density producing plasma intermediate ion with electric propulsion calculates model J _i;

Step 2, when electric propulsion produce the diffusion of plasma reach balance time, the dissufion current that space plasma and electric propulsion produce between plasma in potential barrier is equal with drift current, now pass through without net current in potential barrier, accordingly any one calculating in models of two current densities that step 3 is set up shifted to and derived, obtaining space plasma and electric propulsion and produce potential barrier intensity v and space environment plasma parameter and electric propulsion between plasma and produce the quantitative expression relation between plasma parameter:

$v=\frac{\mathrm{kT}}{q}\·\ln \frac{n_e}{n_i}$

Wherein, k is Boltzmann constant, and T is plasma temperature, and q is the quantity of electric charge that electric propulsion produces electronics in plasma intermediate ion and space plasma, n _efor space plasma density, n _ifor electric propulsion produces plasma density;

When step 3, analysis, determine the space plasma parameter of GEO track, comprise space plasma density n _e, and determine that electric propulsion produces plasma parameter, comprise electric propulsion and produce plasma density n _i; According to determined two kinds of plasma parameters, substitute into described quantitative expression relation and determine that space plasma and electric propulsion produce potential barrier intensity between plasma.

Beneficial effect:

The present invention is directed to electric propulsion and produce plasma to the impact of spacecraft charging and discharging effects, based semiconductor carrier diffusion theory establishes the computing method of potential barrier between space plasma and electric propulsion generation plasma, thus quantitatively obtain potential barrier between space plasma and electric propulsion generation plasma, for spacecraft shield design provides theoretical direction.

Accompanying drawing explanation

Fig. 1 is the process flow diagram that space plasma and electric propulsion produce potential barrier between plasma.

Fig. 2 is the formation physics process schematic that electric propulsion produces plasma potential barrier.

Embodiment

To develop simultaneously embodiment below in conjunction with accompanying drawing, describe the present invention.

Fig. 1 is the process flow diagram that space plasma and electric propulsion produce potential barrier between plasma.It comprises two parts, and Part I is the formation physical process producing plasma potential barrier by analyzing electric propulsion, provides the computation model of potential barrier between space plasma and electric propulsion generation plasma; Part II determines that GEO orbit space plasma parameter and electric propulsion produce plasma parameter, and obtain potential barrier between space plasma and electric propulsion generation plasma according to this model.

First the analysis that electric propulsion produces the formation physical process of plasma potential barrier is carried out.Electric propulsion produces the formation physical process of plasma potential barrier as shown in Figure 2, is Xe ion because electric propulsion produces plasma intermediate ion, and its quality is much larger than electron mass, and therefore the movement velocity of electronics is much larger than the movement velocity of Xe ion.

Therefore, produce in electric propulsion in the diffusion process of plasma, will electronics as shown in Figure 2 and ion distribution be formed, thus define one is pointed to negative charge electric field by positive charge.The formation of this electric field will speed up electric propulsion and produces the diffusion of plasma intermediate ion, and the electronics simultaneously contributed in the natural plasma of space enters satellite surface region, thus affects the conductive environment of satellite surface space natural plasma.

Can find out that electric propulsion produces the diffusion process of charge carrier in the diffusion process of plasma and semiconductor similar, the diffusion process that therefore electric propulsion can be produced plasma is analogous to the diffusion process of charge carrier in semiconductor, set up space plasma and electric propulsion generation plasma diffusion model according to semiconductor carriers diffusion theory, and then obtain the computation model of potential barrier between space plasma and electric propulsion generation plasma.

Electric current in semiconductor material comprises dissufion current and drift current, and therefore its current density, J equals superposing of diffusion current density and drift current density, is embodied as:

$J=q\·n_n\·u_n\·E-q\·D\·\frac{{\∂n}_n}{\∂x}$

In formula, J is hole current density, and q is hole charge amount, n _nfor hole density, u _nmobility and the coefficient of diffusion in hole is respectively with D; for the differential of hole density on unit length x.

Accordingly, the current density calculating equation that the electronics in space plasma and electric propulsion produce plasma intermediate ion is as follows:

$J_i=q\·n_i\·u_i\·E-q\·D_i\·\frac{{\∂n}_i}{\∂x}$

$J_e=q\·n_e\·u_e\·E+q\·D_e\·\frac{{\∂n}_e}{\∂x}---\left(1\right)$

In formula, J _ifor electric propulsion produces the current density of plasma intermediate ion, J _efor the current density of the electronics in space plasma, q is the quantity of electric charge that electric propulsion produces electronics in plasma intermediate ion and space plasma, n _ifor electric propulsion produces plasma intermediate ion density, namely aforesaid electric propulsion produces plasma density, n _efor the electron density in space plasma, i.e. aforesaid space plasma density, u _iand D _ibe respectively mobility and coefficient of diffusion that electric propulsion produces plasma intermediate ion, u _eand D _efor mobility and the coefficient of diffusion of electronics in space plasma, E is the electric field intensity that space plasma and electric propulsion produce between plasma in potential barrier, and x is the unit length of differential.

When the diffusion that electric propulsion produces plasma reaches balance, the dissufion current that space plasma and electric propulsion produce between plasma in potential barrier is equal with drift current, now pass through without net current in potential barrier, any one calculating in model (formula 1) of two current densities set up can be shifted to and be derived accordingly, obtain space plasma and electric propulsion to produce potential barrier intensity v and space environment plasma parameter and electric propulsion between plasma and produce the quantitative expression relation between plasma parameter, detailed process is as follows:

Plasma ion current density is produced for electric propulsion:

$q\·n_i\·u_i\·E=q\·D_i\·\frac{{\∂n}_i}{\∂x}---\left(2\right)$

Due in semiconductor carriers diffusion model, the coefficient of diffusion of charge carrier with the ratio of mobility is therefore analogy is in this programme, can obtain:

$\frac{D_i}{u_i}=\frac{D_e}{u_e}=\frac{\mathrm{kT}}{q}---\left(3\right)$

(3) are substituted into (2), can obtain:

$\frac{\mathrm{kT}}{q}\·\frac{{\∂n}_i}{\∂x}=n_i\·E---\left(4\right)$

In formula, k is Boltzmann constant, and T is plasma temperature.

Simultaneously:

$E=-\frac{\mathrm{dv}}{\mathrm{dx}}---\left(5\right)$

In formula, v is potential barrier intensity;

(5) are substituted into (4), can obtain:

$\frac{\mathrm{kT}}{q}\·\frac{{\∂n}_i}{\∂x}=-n_i\·\frac{\mathrm{dv}}{\mathrm{dx}}---\left(6\right)$

Formula (6) is carried out integration, can obtain:

$v=\frac{\mathrm{kT}}{q}\·\ln \frac{n_e}{n_i}---\left(7\right)$

Formula (7) i.e. space plasma and electric propulsion produce potential barrier intensity v and space environment plasma parameter and electric propulsion between plasma and produce the quantitative expression relation between plasma parameter.

When carrying out actual analysis, perform following steps:

(I) GEO orbit space plasma environment parameter is determined; In this step, GEO orbit space plasma environment parameter comprises space plasma energy and space plasma density, and space plasma energy range is 0.1 ~ 100keV, space plasma density n _ebe 10 ⁶m ^-3.

(II) determine that electric propulsion produces plasma parameter; In this step, electric propulsion generation plasma parameter comprises plasma density, energy density of plasma n _ibe 10 ¹⁵m ^-3.

(III) by step (I) and (II) two kinds of plasma parameters determining in n _eand n _isubstitution formula (7) can determine that space plasma and electric propulsion produce potential barrier intensity v between plasma.

After obtaining potential barrier intensity, this potential barrier intensity can be utilized to carry out the assay of spacecraft charging and discharging effects, specifically, for certain ion L in space plasma, its energy is a value in 0.01keV ~ 100keV, and when potential barrier intensity is greater than the energy of this ion L, this ion L cannot pass through potential barrier and arrive spacecraft, otherwise this ion L will reduce energy through potential barrier.

Cite an actual example below:

I) determine GEO orbit space plasma parameter, wherein, space plasma energy range is 0.1 ~ 100keV, space plasma density n _ebe 10 ⁶m ^-3.

II) determine that electric propulsion produces plasma parameter, wherein, electric propulsion produces plasma density n _ibe 10 ¹⁵m ^-3.

III) by space plasma density 10 ⁶m ^-3producing plasma density with electric propulsion is 10 ¹⁵m ^-3substitution formula (7), calculating and obtaining potential barrier intensity between space plasma and electric propulsion generation plasma is 40V.

In sum, these are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention.Within the spirit and principles in the present invention all, any amendment done, equivalent replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (1)

1. space plasma and electric propulsion produce a potential barrier quantitative analysis method between plasma, it is characterized in that, comprising:

Step one, diffusion process electric propulsion being produced plasma are analogous to the diffusion process of charge carrier in semiconductor, set up the diffusion model of space plasma and electric propulsion generation plasma according to semiconductor carriers diffusion theory, the current density comprising electronics in space plasma calculates model J _ethe current density producing plasma intermediate ion with electric propulsion calculates model J _i;

Step 2, when electric propulsion produce the diffusion of plasma reach balance time, the dissufion current that space plasma and electric propulsion produce between plasma in potential barrier is equal with drift current, now pass through without net current in potential barrier, accordingly any one calculating in models of two current densities that step 3 is set up shifted to and derived, obtaining space plasma and electric propulsion and produce potential barrier intensity v and space environment plasma parameter and electric propulsion between plasma and produce the quantitative expression relation between plasma parameter:

$v=\frac{\mathrm{kT}}{q}\·\ln \frac{n_e}{n_i}$

Wherein, k is Boltzmann constant, and T is plasma temperature, and q is the quantity of electric charge that electric propulsion produces electronics in plasma intermediate ion and space plasma, n _efor space plasma density, n _ifor electric propulsion produces plasma density;

When step 3, analysis, determine the space plasma parameter of GEO track, comprise space plasma density n _e, and determine that electric propulsion produces plasma parameter, comprise electric propulsion and produce plasma density n _i; According to determined two kinds of plasma parameters, substitute into described quantitative expression relation and determine that space plasma and electric propulsion produce potential barrier intensity between plasma.