CN104061137B - Method according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit - Google Patents

Abstract

A kind of method according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit, relates to plasma propulsion field.The present invention is to solve existing ground vacuum Installed System Memory background gas backflow cause hall thruster in orbit time off-design technical specification.The in vitro hall thruster of the present invention is tested, calculate hall thruster mass flow of backflowing of background gas under different background pressure, and the contribution estimation conversion factor of ion pair thrust of backflowing according to background gas, the thrust of hall thruster in laboratory is modified, using revised thrust as thrust time in orbit.The present invention is applicable to the correction of flight hall thruster performance parameter in-orbit.

Description

Method according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit

Technical field

This method relates to plasma propulsion field.

Background technology

Hall thruster progressively becomes the aerospace craft such as satellite, detector with features such as its high efficiency, high specific impulse, low thrusts Important motivity device.Along with the development of various countries' aerospace industry, the research to hall thruster is more deep.Due to existing Research at hall thruster is all to carry out under the vacuum environment of ground test equipment simulation, the vacuum environment of ground simulation It is extremely difficult to the vacuum condition of actual space.Generally, the vacuum pressure of actual space is in 10^ (-7) Pa magnitude, and Hall pushes away Power device is lighted a fire when running in ground vacuum system, and due to equipment and the restriction of experimental expenses, background gas pressure is generally greater than 10^ (-4) Pa, is the most at least higher than space environment pressure an order of magnitude.Additionally, vacuum back pressure also can be tested in background gas Body, the impact of vacuum pumping speed are fluctuated within the specific limits.

When hall thruster runs in the case of ground vacuum tank this vacuum back pressure is of a relatively high, background gas cognition is passed through Diffusion enters high energy particle in discharge channel, with passage and collides ionization, and after ionization, the ion of generation is through electric field acceleration Return in vacuum tank.And under the preferable vacuum environment of space, the pressure that in passage, gas pressure intensity is formed with background gas pressure Gradient is the least, therefore, returns to the background gas in discharge channel by diffusion few, is negligible.

In existing ground vacuum system, inevitably there is backflowing of background gas, enter background gas in passage together with Working medium gas equally participates in the ionization accelerator of gas in passage, and this will certainly have influence on the thrust of thruster, efficiency, put The electricity macro property parameter such as electric current and specific impulse, the technical specification of off-design when causing hall thruster in orbit.

Summary of the invention

The present invention is to solve that existing ground vacuum Installed System Memory causes hall thruster in orbit backflowing of background gas Time off-design technical specification.And then propose a kind of according to ground experiment parameter correction flight hall thruster thrust in-orbit The method of parameter.

Process according to the ground experiment parameter correction method of flight hall thruster thrust parameter in-orbit is:

Step one: calculate hall thruster mass flow of backflowing of background gas under different background pressureConcrete behaviour As step it is:

Carry out hall thruster experiment in the lab, if atom obeys Maxwell's distribution in hall thruster passage, then Atomic number in unit interval unit are such as formula (1), i.e. Collision Number be:

$\begin{array}{c}J=\underset{0}{\overset{\mathrm{\∞}}{\∫}}Nf\left(v\right)dv\·vdtdA/dtdA\\ =N{\left(\frac{m}{2\mathrm{\π}kT}\right)}^{1/2}\underset{0}{\overset{\mathrm{\∞}}{\∫}}{e}^{-\frac{m}{2kT}{v}^2}vdv\\ =\frac{1}{4}N\stackrel{\→}{v}\end{array}---\left(1\right)$

Wherein: v represents atomic velocity scalar,Represent atomic velocity vector, k=1.38 × 10^-23Represent Bohr The most graceful constant, m is background gas atoms quality, t express time, and T represents thermodynamic temperature during laboratory work, A table Showing hall thruster channel outlet sectional area, N represents that population density, f (v) are Distribution and Maxwell's Velocity function, and e is certainly So truth of a matter of logarithm, its value is about 2.7182；

According to The Ideal-Gas Equation, PV_Body=nRT, can obtain:Due to R=k N_A, obtain particle Number density is

$N=\frac{P}{kT}---\left(2\right)$

Wherein, P is gas pressure in vacuum tank, V_BodyFor gas volume, n is the amount of gaseous matter, and R is ideal gas constant, N_AFor Avogadro's number；

Formula (2) is substituted into formula (1) can obtain:

$J=\frac{1}{4}\frac{P}{kT}\stackrel{\→}{v}=\frac{P}{kT}\sqrt{\frac{kT}{2\mathrm{\π}m}}---\left(3\right)$

Background gas backflows mass flowAs shown in formula (4)

When being approximately considered hall thruster work, accelerating region pressure is under vacuum premise, formula (3) is substituted into formula (4) and obtains To the backflow relation of mass flow and background pressure of background gas it is:

Wherein,Backflowing mass flow for background gas, A is hall thruster channel outlet sectional area, and P is gas in vacuum tank Body pressure, T represents thermodynamic temperature during laboratory work；

In changing vacuum tank in the lab, gas pressure P tests, and obtains background under corresponding back pressure according to formula (5) Gas backflow mass flow, draws the mass flow curve chart that backflows, and can search background gas under corresponding back pressure according to curve chart and return Current mass flow；

Step 2: according to background gas backflow ion pair thrust contribution estimate conversion factor δ concrete operation step be:

During hall thruster work, given the Working medium gas mass flow main flow mass flow determined by effusion meterMainstream gas enters discharge channel ionization through gas distributor and produces ion, i.e. main flow ion, and background gas backflows Ionizing generation under crossed electric and magnetic field to discharge channel to backflow ion, main flow ion is discharged voltage together with the ion that backflows to accelerate Ejection produces thrust；And after background gas enters discharge channel, anode can not be arrived, the gas ionization that therefore backflows obtains Accelerating potential is less than the discharge voltage of hall thruster, can be calculated the tribute of ion pair thrust of backflowing by multiple-grid probe quantitative Offer；

Many gridded probes, regulation receiver stage is utilized to prevent voltage, obtain many gridded probes VA characteristic curve, to VA characteristic curve Carry out single order numerical differentiation, and use small wave converting method to be filtered denoising Processing, obtain ion energy distribution function；From There are two peaks in sub-Energy distribution, relatively ebb is low energy ion (backflows ion), and higher peak is energetic ion (main flow ion), The quasi-molecular ions that backflows is different with main flow quasi-molecular ions position, illustrates that the energy that background gas obtains from electric field after entering passage ionization is bright Aobvious less than the energy obtained after anodic gas ionization；What two quasi-molecular ions were corresponding is backflow quasi-molecular ions and main flow quasi-molecular ions respectively, Being that low energy ion represents that the energy of the ion that backflows is low compared with ebb, higher peak is that energetic ion represents that the energy of main flow ion is high, from Sub-energy is supplied by voltage, defines, hence with the accelerating potential of main flow ion and the accelerating potential of the ion that backflows, the particle pair that backflows The contribution conversion factor such as formula (6) of thrust:

Wherein U_{Add and backflow}Represent the accelerating potential that the ion that backflows is obtained in discharge channel, U_{Add main flow}Represent that main flow ion is being put

The accelerating potential obtained in electric channel；

Step 3: during hall thruster work, given the Working medium gas mass flow determined, i.e. main flow quality by effusion meter FlowAccording to mass flow of backflowingMain flow mass flowWith conversion factor δ, Hall in laboratory is pushed away Thrust T of power device_ExperimentIt is modified, as shown in formula (7)

The corrected thrust calculated according to correction formula (7), thrust during as hall thruster in orbit.

The in vitro hall thruster of the present invention is tested, and calculates hall thruster background gas under different background pressure The mass flow of backflowing of bodyAnd contribution estimation conversion factor δ of ion pair thrust of backflowing according to background gas, according to FormulaThrust is modified, as thrust time in orbit.After correction, permissible Determine that flight thrust device thrust is relative to low 3 5mN of ground experiment test thrust in-orbit.

Accompanying drawing explanation

Fig. 1 hall thruster structure diagram；

In figure, exterior loop 1, interior loop 2, interpole coil 3, magnetic conductor 4, pottery 5, anode 6；

Tri-magnet exciting coils of Fig. 2 are connected in series mode excitation；

Tri-magnet exciting coil independent excitations of Fig. 3；

The graph of a relation of Fig. 4 background pressure and mass flow of backflowing；

The ion energy distribution of Fig. 5 difference back pressure；

Detailed description of the invention

Detailed description of the invention one: according to the process of the ground experiment parameter correction method of flight hall thruster thrust parameter in-orbit For:

Step one: calculate hall thruster mass flow of backflowing of background gas under different background pressureConcrete behaviour As step it is:

Carry out hall thruster experiment in the lab, if atom obeys Maxwell's distribution in hall thruster passage, then Atomic number in unit interval unit are such as formula (1), i.e. Collision Number be:

$\begin{array}{c}J=\underset{0}{\overset{\mathrm{\∞}}{\∫}}Nf\left(v\right)dv\·vdtdA/dtdA\\ =N{\left(\frac{m}{2\mathrm{\π}kT}\right)}^{1/2}\underset{0}{\overset{\mathrm{\∞}}{\∫}}{e}^{-\frac{m}{2kT}{v}^2}vdv\\ =\frac{1}{4}N\stackrel{\→}{v}\end{array}---\left(1\right)$

Wherein: v represents atomic velocity scalar,Represent atomic velocity vector, k=1.38 × 10^-23Represent Bohr The most graceful constant, m is background gas atoms quality, t express time, and T represents thermodynamic temperature during laboratory work, A table Showing hall thruster channel outlet sectional area, N represents that population density, f (v) are Distribution and Maxwell's Velocity function, and e is certainly So truth of a matter of logarithm, its value is about 2.7182；

According to The Ideal-Gas Equation, PV_Body=nRT, can obtain:Due to R=k N_A, obtain particle Number density is

$N=\frac{P}{kT}---\left(2\right)$

Wherein, P is gas pressure in vacuum tank, V_BodyFor gas volume, n is the amount of gaseous matter, and R is ideal gas constant, N_AFor Avogadro's number；

Formula (2) is substituted into formula (1) can obtain:

$J=\frac{1}{4}\frac{P}{kT}\stackrel{\→}{v}=\frac{P}{kT}\sqrt{\frac{kT}{2\mathrm{\π}m}}---\left(3\right)$

Background gas backflows mass flowAs shown in formula (4)

When being approximately considered hall thruster work, accelerating region pressure is under vacuum premise, formula (3) is substituted into formula (4) and obtains To the backflow relation of mass flow and background pressure of background gas it is:

Wherein,Backflowing mass flow for background gas, A is hall thruster channel outlet sectional area, and P is gas in vacuum tank Body pressure, T represents thermodynamic temperature during laboratory work；

In changing vacuum tank in the lab, gas pressure P tests, according to corresponding experimental data, according to formula (5) Obtain background gas under corresponding back pressure to backflow mass flow, draw the mass flow curve chart that backflows, phase can be searched according to curve chart Background gas under back pressure is answered to backflow mass flow, such as Fig. 4；

Step 2: according to background gas backflow ion pair thrust contribution estimate conversion factor δ concrete operation step be:

Hall thruster as it is shown in figure 1, during its work, give the Working medium gas mass flow master determined by effusion meter Current mass flowMainstream gas enters discharge channel ionization through gas distributor and produces ion, i.e. main flow ion, the back of the body Scape gas backflow ionizes generation under crossed electric and magnetic field to discharge channel and backflows ion, and main flow ion is put together with the ion that backflows Piezoelectric voltage is accelerated ejection and is produced thrust；And after background gas enters discharge channel, anode can not be arrived, therefore backflow gas The accelerating potential that ionization obtains is less than the discharge voltage of hall thruster, can calculate, by multiple-grid probe quantitative, the ion that backflows Contribution to thrust；

Many gridded probes, regulation receiver stage is utilized to prevent voltage, obtain many gridded probes VA characteristic curve, to VA characteristic curve Carry out single order numerical differentiation, and use small wave converting method to be filtered denoising Processing, obtain ion energy distribution function；As Shown in Fig. 5, there are two peaks in ion energy distribution, relatively ebb is low energy ion (backflows ion), and higher peak is energetic ion (main flow ion), the quasi-molecular ions that backflows is different with main flow quasi-molecular ions position, illustrates that background gas enters after passage ionizes from electric field The energy obtained after energy anodic gas the to be significantly less than ionization obtained；What two quasi-molecular ions were corresponding is the quasi-molecular ions that backflows respectively With main flow quasi-molecular ions, be that low energy ion represents that the energy of the ion that backflows is low compared with ebb, higher peak be energetic ion represent main flow from The energy of son is high, and ion energy is supplied by voltage, hence with accelerating potential and the accelerating potential of the ion that backflows of main flow ion Definition is backflowed the particle contribution conversion factor such as formula (6) to thrust:

Wherein U_{Add and backflow}Represent the accelerating potential that the ion that backflows is obtained in discharge channel, U_{Add main flow}Represent that main flow ion is being put

The accelerating potential obtained in electric channel；

Step 3: during hall thruster work, given the Working medium gas mass flow determined, i.e. main flow quality by effusion meter FlowAccording to mass flow of backflowingMain flow mass flowWith conversion factor δ, Hall in laboratory is pushed away Thrust T of power device_ExperimentIt is modified, as shown in formula (7)

The corrected thrust calculated according to correction formula (7), thrust during as hall thruster in orbit.

Hall thruster in laboratory is tested by the present invention, calculates hall thruster background gas under different background pressure The mass flow of backflowing of bodyAnd contribution estimation conversion factor δ of ion pair thrust of backflowing according to background gas, according to FormulaThrust is modified, as thrust time in orbit.

Detailed description of the invention two: the hall thruster channel outlet cross section in step one formula (5) described in present embodiment Shown in long-pending A such as formula (8)

$A=\mathrm{\π}(R_w^2-R_n^2)---\left(8\right)$

Wherein, R_wRepresent thruster outside diameter of passage, R_nRepresent thruster channel internal diameter.

Other step is identical with detailed description of the invention one.

Detailed description of the invention three: " obtain ion energy distribution function " in present embodiment step 2 and can pass through difference, line Property difference approach obtains.

Other step is identical with detailed description of the invention two.

Detailed description of the invention four: combine Fig. 2, Fig. 3 and present embodiment is described, described in present embodiment according to ground experiment When the method for parameters revision flight hall thruster thrust parameter in-orbit utilizes hall thruster to test, hall thruster Three magnet exciting coils are used to be connected in series mode excitation or use three magnet exciting coil independent excitations.

Other step is identical with detailed description of the invention three.

Specific embodiment

Choosing gas pressure in vacuum tank is 3.0 × 10^-2Pa tests, when running under hall thruster is in design conditions, Discharge voltage 368V, three magnet exciting coil series connection of hall thruster, as in figure 2 it is shown, series excitation electric current is 3.88A, Quality of anode flow 4.4mg/s, cathode quality flow 0.29mg/s.When carrying out ground experiment, experiment is measured thrust and is 89.4mN, is calculated specific impulse 1939s according to specific impulse formula.

According to step one, utilize formula (5) to be calculated now background gas under this vacuum pressure and backflow mass flow m_Backflow For 0.2925mg/s.

According to step 2, as it is shown in figure 5, data show that the ion accelerating voltage that backflows is 80V in curve, main flow acceleration of ions Voltage be discharge voltage be 300V, with this, obtain backflowing particle to pushing away according to main flow ion and the accelerating potential of ion of backflowing The contribution conversion factor of power:

According to step 3: utilize corrected thrust formula can obtain under this experiment condition hall thruster reality in orbit time Thrust is 86.369mN.

Claims (4)

1. the method according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit, it is characterised in that its bag Include following step:

Step one: calculate hall thruster mass flow of backflowing of background gas under different background pressureConcrete operations Step is:

If atom obeys Maxwell's distribution in hall thruster passage, then the atomic number in unit interval unit are is as public Formula (1), i.e. Collision Number be:

$\begin{array}{c}J=\underset{0}{\overset{\∞}{\∫}}\mathrm{Nf}\left(v\right)\mathrm{dv}\·\mathrm{vdtdA}/\mathrm{dtdA}\\ =N{\left(\frac{m}{2\mathrm{\πkT}}\right)}^{1/2}\underset{0}{\overset{\∞}{\∫}}{e}^{-\frac{m}{2\mathrm{kT}}{v}^2}\mathrm{vdv}\\ =\frac{1}{4}N\stackrel{\→}{v}\end{array}---\left(1\right)$

Wherein: v represents atomic velocity scalar,Represent atomic velocity vector, k=1.38 × 10^-23Represent Bohr hereby Graceful constant, m is background gas atoms quality, t express time, and T represents thermodynamic temperature during laboratory work, A Hall Thruster channel outlet sectional area, N represents that population density, f (v) are Distribution and Maxwell's Velocity function, e natural logrithm The truth of a matter；

According to The Ideal-Gas Equation, PV_Body=nRT, can obtain:Due to R=k N_A, obtain population Density is

$N=\frac{P}{\mathrm{kT}}---\left(2\right)$

Wherein, P is gas pressure in vacuum tank, V_BodyFor gas volume, n is the amount of gaseous matter, and R is ideal gas constant, N_A For Avogadro's number；

Formula (2) is substituted into formula (1) can obtain:

$J=\frac{1}{4}\frac{P}{\mathrm{kT}}\stackrel{\→}{v}=\frac{P}{\mathrm{kT}}\sqrt{\frac{\mathrm{kT}}{2\mathrm{\πm}}}---\left(3\right)$

Background gas backflows mass flowAs shown in formula (4)

When being approximately considered hall thruster work, accelerating region pressure is under vacuum premise, formula (3) is substituted into formula (4) and obtains To the backflow relation of mass flow and background pressure of background gas it is:

Wherein,Backflowing mass flow for background gas, A is hall thruster channel outlet sectional area, and P is gas in vacuum tank Body pressure；

In changing vacuum tank in the lab, gas pressure P tests, and obtains background gas under corresponding back pressure according to formula (5) Body backflows mass flow；

Step 2: according to background gas backflow ion pair thrust contribution estimate conversion factor δ concrete operation step be:

Many gridded probes, regulation receiver stage is utilized to prevent voltage, obtain many gridded probes VA characteristic curve, to VA characteristic curve Carry out single order numerical differentiation, and use small wave converting method to be filtered denoising Processing, obtain ion energy distribution function；Two What individual quasi-molecular ions was corresponding is respectively backflows quasi-molecular ions and main flow quasi-molecular ions, relatively ebb are the energy that low energy ion represents the ion that backflows Low, higher peak is that energetic ion represents that the energy of main flow ion is high, and ion energy is supplied by voltage, utilizes adding of main flow ion The accelerating potential definition of speed voltage and the ion that backflows is backflowed the particle contribution conversion factor such as formula (6) to thrust:

Wherein U_{Add and backflow}Represent the accelerating potential that the ion that backflows is obtained in discharge channel, U_{Add main flow}Represent that main flow ion is in electric discharge The accelerating potential obtained in passage；

Step 3: during hall thruster work, given the Working medium gas mass flow determined, i.e. main flow quality by effusion meter FlowAccording to mass flow of backflowingMain flow mass flowWith conversion factor δ to Hall thrust in laboratory Thrust T of device_ExperimentIt is modified, as shown in formula (7)

The corrected thrust calculated according to correction formula (7), thrust during as hall thruster in orbit.

The most according to claim 1 a kind of according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit Method, it is characterised in that shown in hall thruster channel outlet sectional area A such as formula (8) in step one formula (5)

$A=\mathrm{\π}(R_w^2-R_n^2)---\left(8\right)$

Wherein, R_wRepresent thruster outside diameter of passage, R_nRepresent thruster channel internal diameter.

The most according to claim 2 a kind of according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit Method, it is characterised in that " obtain ion energy distribution function " in step 2 and obtained by difference, linear difference method.

The most according to claim 3 a kind of according to ground experiment parameter correction flight hall thruster thrust parameter in-orbit Method, it is characterised in that when utilizing hall thruster to test, hall thruster uses three magnet exciting coils to be connected in series Mode excitation or three magnet exciting coil independent excitations of employing.