CN107091210B - A kind of pulsed plasma thruster based on capillary discharging - Google Patents

Abstract

The disclosure relates to a pulsed plasma thruster based on capillary discharge, including a power processing unit, a main capacitor, a semiconductor spark plug, an ignition circuit, a main discharge circuit, a propellant working medium, a cathode nozzle, an anode and a plexiglass casing. In the present disclosure, by introducing a cathode nozzle, the main discharge current and the plasma movement direction form a certain angle, and electromagnetic acceleration is introduced under the action of a self-induced magnetic field. Different from the traditional electromagnetic acceleration pulsed plasma thruster, this disclosure makes full use of the electrothermal acceleration mechanism to improve the energy utilization efficiency of the pulsed plasma thruster. At a low power level, it can improve the overall efficiency of the system and is more suitable for low-power microsatellites. application occasions.

Description

A Pulsed Plasma Thruster Based on Capillary Discharge

technical field

The disclosure belongs to the field of pulse power technology and power machinery technology, and relates to a pulse plasma thruster based on capillary discharge.

Background technique

1. Traditional cold air propulsion and chemical propulsion systems need to use propellant storage devices and supply systems, which makes the overall mass of the device large and the structure complex. At the same time, the above two propulsion systems have small specific impulse and low efficiency, which largely limits their space applications in microsatellites. Since the former Soviet Union first applied the pulsed plasma thruster to the Zond 2 aircraft in the 1960s, as a new type of electric propulsion system, the pulsed plasma thruster has been greatly developed. And with the expansion of the micro-satellite application market, pulsed plasma thrusters have a wide range of applications in micro-satellites performing high-precision tasks due to their advantages such as high specific impulse, small mass, simple structure, short development cycle, and the ability to provide micro-adjustable thrust. application prospects.

2. The traditional pulsed plasma thruster adopts the electromagnetic acceleration mechanism, and the energy storage capacitor is connected through two parallel electrode plates, and the propellant working medium is placed between the two plates. In the initial energy storage state, the initial charged particles are introduced by means of spark plug triggering to induce surface discharge of the capacitor on the surface of the propellant. The action of the Lenz force accelerates the ejection outwards and generates thrust.

3. Although the electromagnetic pulsed plasma thruster uses a solid propellant, the propellant working fluid and the thruster body are combined to form a modular device, but because the electromagnetic force can only accelerate charged particles, it has little effect on the acceleration of neutral molecules. Experiments have shown that the mass of neutral molecules produced by ablation accounts for 70% to 90% of the total mass of ablation products, which makes the acceleration efficiency of the pulsed plasma thruster low and affects the overall energy conversion efficiency of the thruster. At the same time, due to the existence of the hysteresis ablation phenomenon and the particle emission effect, the utilization rate of the working medium is low, and there are still great obstacles in the wide application of the low-power micro-satellite.

Contents of the invention

Based on this, the present invention discloses a pulsed plasma thruster based on capillary discharge,

The thruster includes: a power processing unit, a semiconductor spark plug, an ignition circuit, a main discharge circuit and a propellant working fluid;

The power processing unit is used to provide the voltage required for the thruster to work, charge the main capacitor in the main discharge circuit and supply power to the ignition circuit;

The ignition circuit is used to output pulse high voltage to cause surface discharge of semiconductor spark plug to generate initial charged particles;

The initial charged particles generated by the semiconductor spark plug enter the propellant working fluid, and generate plasma through continuous impact ionization;

The propellant working medium is capillary type, and with the generation of plasma, surface flashover occurs on the surface of the propellant working medium to form the discharge of the main capacitor in the main discharge circuit;

The main discharge circuit is used to store and transmit the electric energy provided by the power processing unit, ablate the propellant working fluid and accelerate the plasma, convert the energy of the main capacitor into plasma kinetic energy, thereby forming a plasma jet and generating thrust.

Compared with the prior art, the present disclosure has beneficial technical effects:

1. The new pulsed plasma thruster based on capillary discharge provided by the present invention adopts the mechanism of electrothermal acceleration of plasma, which is different from the traditional electromagnetic acceleration mechanism, and realizes the neutral molecules that account for most of the mass of ablation products. Sufficient acceleration; in the present invention, the energy deposition efficiency of the plasma arc reaches more than 50%, which is conducive to improving the overall energy utilization efficiency of the thruster.

2. The present invention adopts a high-performance semiconductor spark plug, which can discharge along the surface and generate charged particles at a lower DC voltage, simplify the insulation structure, and improve the overall safety and reliability of the ignition circuit; use the semiconductor switch to control the ignition circuit, which can Precisely adjust the operating frequency to achieve the purpose of adjusting the power consumption, thrust and impulse of the thruster.

3. The present invention realizes the modular combination of the propellant working medium and the thruster body, has a simple structure, fewer moving parts, and high reliability. The design of the coaxial structure makes the overall size of the thruster small and easy to install. The size of the propellant working medium can be conveniently adjusted under the same external structure to meet the requirements of different performance output parameters.

4. The present invention adopts the expanding nozzle, increases the plasma jet angle and introduces an electromagnetic acceleration mechanism to further increase the particle exit velocity, improve thrust efficiency and obtain high specific impulse.

Description of drawings

Figure 1 is a schematic diagram of a pulsed plasma thruster work implementation device based on capillary discharge;

Figure 2 is a typical discharge waveform of a pulsed plasma thruster based on capillary discharge;

As shown in the figure: 1 is the cathode nozzle; 2 is the tungsten electrode of the spark plug; 3 is the cathode connection bolt; 4 is the semiconductor layer of the spark plug; 5 is the propellant working fluid; 6 is the plexiglass shell; 7 is the anode; ; 9 is the main discharge capacitor; 10 is the simulated vacuum environment; 11 is the power processing unit; 12 is the ignition circuit.

Detailed ways

Embodiments of the present invention are described in detail below in conjunction with accompanying drawings:

In one embodiment, the present invention discloses a pulsed plasma thruster based on capillary discharge,

The thruster includes: a power processing unit, a semiconductor spark plug, an ignition circuit, a main discharge circuit and a propellant working fluid;

The power processing unit is used to provide the voltage required for the thruster to work, charge the main capacitor in the main discharge circuit and supply power to the ignition circuit;

The ignition circuit is used to output pulse high voltage to cause surface discharge of semiconductor spark plug to generate initial charged particles;

The initial charged particles generated by the semiconductor spark plug enter the propellant working fluid, and generate plasma through continuous impact ionization;

The propellant working medium is capillary type, and with the generation of plasma, surface flashover occurs on the surface of the propellant working medium to form the discharge of the main capacitor in the main discharge circuit;

The main discharge circuit is used to store and transmit the electric energy provided by the power processing unit, ablate the propellant working fluid and accelerate the plasma, convert the energy of the main capacitor into plasma kinetic energy, thereby forming a plasma jet and generating thrust.

More preferably, the thruster also includes: a cathode nozzle, an anode and a plexiglass casing;

The cathode nozzle is used to accelerate the plasma;

The plexiglass shell is used for connecting the cathode nozzle, the anode and the propellant working fluid.

In this embodiment, in order to solve the problems of low acceleration efficiency of heavy particles and low energy conversion efficiency (5% to 10%) of the existing electromagnetic acceleration pulse plasma thruster, the structure is simple, the consistency of repeated work is good, and it has high specific impulse Parameters and high thrust efficiency of pulsed plasma thruster based on capillary discharge. In this embodiment, relatively low-temperature and high-density plasma is generated by capillary discharge, so that a huge pressure difference is formed between the inside of the working medium cavity and the external vacuum environment, so that the plasma can obtain sufficient electrothermal acceleration, and the performance of the pulsed plasma thruster is improved.

This embodiment is achieved through the following technical solutions:

A novel pulse plasma thruster based on capillary discharge. The invention comprises: a power processing unit, a main capacitor, a semiconductor spark plug, an ignition circuit, a main discharge circuit, propellant working fluid, a cathode nozzle, an anode and a plexiglass shell. Among them: the propellant working medium is capillary, the cathode nozzle and the anode are distributed at both ends of the working medium cavity, and are connected to the external plexiglass shell through threads, and the whole device is a coaxial structure; the high-performance semiconductor spark plug is installed on the cathode nozzle, The ignition circuit outputs DC high voltage to make the spark plug discharge to generate initial plasma. The power processing unit charges the main capacitor through the transmission line, and the two ends of the capacitor are connected to the cathode and anode through the transmission line to form the main discharge circuit. The overall circuit is very compact to reduce the loop inductance and increase the electrothermal acceleration efficiency.

In one embodiment, the ignition circuit includes: an ignition capacitor, a high voltage diode for isolation, an ignition switch and a pre-trigger circuit;

The high-voltage end of the ignition capacitor is connected to one end of the ignition switch through a high-voltage diode for isolation, and the low-voltage end is connected to the cathode nozzle of the thruster;

The pre-trigger circuit outputs a pulse signal to drive the ignition switch to discharge the ignition capacitor to the semiconductor spark plug to generate initial charged particles.

In this embodiment, the ignition circuit in the present invention includes an ignition capacitor, a high voltage diode for isolation, an ignition switch and a corresponding pre-trigger circuit. The capacity of the ignition capacitor is 0.1μF. The DC module charges the ignition capacitor to 600V~1000V through the charging resistor. The high voltage end of the ignition capacitor is connected to one end of the ignition switch through the isolation high voltage diode, and the low voltage end is connected to the cathode nozzle of the thruster. The pre-trigger circuit outputs a pulse signal to drive the ignition switch to discharge the ignition capacitor to the spark plug to generate initial charged particles. The isolation high-voltage diode is used to isolate the main discharge circuit and the ignition circuit, avoiding the reduction of energy deposition efficiency in the plasma arc caused by the shunting of the main discharge current to the ignition circuit.

First, the ignition circuit outputs a pulse voltage of 600V to 1000V to induce surface discharge of the semiconductor spark plug and generate some charged particles. Under the action of the electric field force, it enters the capillary cavity and collides with the surface of the working medium, generating more charged particles through impact ionization. The increase in the number of charged particles causes the insulation level in the capillary to decrease, and with the formation of the plasma region, the main capacitor, cathode nozzle, anode and capillary cavity form a discharge channel, and the main discharge is formed. The large current of the main discharge deposits energy in the plasma channel, generates a large amount of heat and ablates the capillary tube wall. The confinement effect of the capillary tube wall on the arc cools the arc through ablation on the one hand, and makes the PTFE molecules Fully ionized, producing more particles. The capillary cavity is quickly filled with high-temperature and high-pressure plasma, and under the action of the huge pressure on the propellant surface, the plasma is fully accelerated and ejected outward to form a jet to generate thrust.

In one embodiment, the propellant working medium adopts solid polytetrafluoroethylene material;

The propellant working medium is a coaxial capillary type, and the length and inner diameter of the working medium can be changed according to the output parameters required by the space mission of the thruster;

The internal diameter of the capillary working fluid tube is 1mm-10mm, and the length is 9mm-20mm.

In this embodiment, the propellant working medium is made of solid polytetrafluoroethylene material, which can be stored for a long time in a space environment without complicated storage devices and supply systems. This embodiment proposes a new propellant working medium structure, that is, the coaxial capillary type, which can change the length and inner diameter of the working medium according to the required output parameters, eliminating the need for a constant force spring required by the traditional propellant supply system. Simplified working medium supply mode. At the same time, the capillary cavity can constrain the arc, and the discharge arc can evenly ablate the surface of the working fluid, making the ionization and decomposition of the working fluid more complete, and can work stably within the rated working times, and the output parameters can remain relatively stable. The capillary-type propellant working medium can further restrain the particles produced by hysteresis ablation from escaping freely in the vacuum, making them attached to the working medium or the electrode surface, and can be ejected after acceleration in the next discharge process, inhibiting the particles launch effect.

In one embodiment, the pre-trigger circuit includes a capacitor bank, a semiconductor switch, a control circuit, a protection diode and a pulse transformer;

The control circuit is used to turn on the semiconductor switch;

The capacitor bank is used to discharge the primary side of the pulse transformer, and output pulse high voltage on the secondary side of the pulse transformer, which is applied to the trigger stage and the low voltage end of the ignition switch to conduct it.

In this embodiment, the pre-trigger circuit includes a capacitor bank, a semiconductor switch, a corresponding control circuit, a protection diode and a pulse transformer. Among them, the capacitor bank uses two 1.0μF capacitors connected in parallel, and the charging voltage is 0-200V. After the semiconductor switch is turned on through the control circuit, the capacitor discharges the primary side of the pulse transformer, and outputs pulse high voltage on the secondary side of the pulse transformer, which is applied to the trigger stage and the low voltage end of the ignition switch to turn it on. The operating frequency of the pulse plasma thruster can be adjusted by adjusting the frequency at which the control circuit turns on the semiconductor switch, so that it can work at a repetition rate of 1 Hz at the highest, and the output performance is consistent.

In one embodiment, the semiconductor material of the semiconductor spark plug is based on silicon carbide, which is formed by mixing and sintering zirconium dioxide, aluminum oxide and glass with silicon carbide in a certain proportion, with a porosity of 5% and a water absorption rate of 0.8%.

In this embodiment, the material of the semiconductor spark plug is based on silicon carbide, zirconia, aluminum oxide and glass are mixed and sintered with silicon carbide in a certain proportion, the porosity is 5%, and the water absorption rate is 0.8. %, which can effectively improve the carbon deposition on the surface of the spark plug and increase the service life of the thruster. Charged particles can be released along the surface by flashover at a DC voltage of 600V in vacuum.

In one embodiment, the cathode nozzle is in the shape of an expanding nozzle, the half angle of the cathode nozzle is 15°-30°, and the length is 10mm-25mm;

The cathode nozzle and the plexiglass shell are threaded and tightly fitted.

In one embodiment, the anode is a hollow cylinder, and the anode and the plexiglass shell are threaded, and a margin of 0.8-1.2mm is left to ensure the cooperation with the propellant working medium.

In this embodiment, the cathode nozzle and the anode are arranged in a coaxial structure, and the anode is provided with an external thread to connect with the plexiglass shell, so that the length of the propellant working medium can be adjusted more conveniently. The cathode is set in the shape of an expanding nozzle, and is connected with the plexiglass casing through an internal thread. The half opening angle of the cathode nozzle is 15°-30°, and the length is 10mm-25mm. The expansion nozzle is beneficial to increase the plasma jet angle and improve the electrothermal acceleration efficiency of the pulsed plasma thruster. At the same time, due to the existence of the expansion angle, the main discharge current is at a certain angle to the plasma movement direction, and due to the existence of the self-induced magnetic field, an electromagnetic acceleration mechanism will be introduced to accelerate the plasma in the axial direction by using the Lorentz force , improve energy conversion efficiency and specific impulse.

In one embodiment, the thruster works in the form of pulses, the energy consumed during the work is controlled by the capacity of the main capacitor and the charging voltage, the working frequency is 0-1 Hz, and the pulse working time is 4-5 μs.

In one embodiment, the capacity of the main capacitor is 1 μF˜4.5 μF, the charging voltage is 1 kV˜3 kV, and the initial energy is 0.5J˜20.25J.

In this embodiment, both ends of the main capacitor are respectively connected to the anode and cathode nozzles of the pulse plasma thruster. The capacity of the main capacitor is 1μF-4.5μF, the charging voltage is 1kV-3kV, and the initial energy is 0.5J-20.25J.

In one embodiment, referring to FIG. 1 , the present invention discloses a pulsed plasma thruster based on capillary discharge. This example includes a cathode nozzle 1, a spark plug tungsten electrode 2, a cathode terminal bolt 3, a spark plug semiconductor layer 4, and a propellant Working medium 5 , plexiglass casing 6 , anode 7 , anode terminal bolt 8 , main discharge capacitor 9 , vacuum chamber 10 , power processing unit 11 and ignition circuit 12 . In the present invention, the outer diameter of the thruster is 24 mm, and the total length is 43 mm to 54 mm

As shown in Figure 1, according to the actual working environment, the present invention is placed in a vacuum chamber 10, which can provide a vacuum environment with a vacuum degree below 5×10 ⁻³ Pa. When the present invention is working, the main discharge capacitor 9 is charged to the rated voltage through the power processing unit 11 . After the ignition command arrives, the ignition circuit 12 applies a DC voltage to the tungsten electrode 2, and a creeping discharge occurs on the spark plug semiconductor layer 4, and the initial charged particles are driven by the electric field formed by the anode 7 and the cathode nozzle 1. In the propellant working medium 5, plasma is generated through continuous impact ionization. With the decrease of the impedance in the channel, the surface of the propellant working medium 5 flashes along the surface to form the discharge of the main capacitor 9, and the plasma is formed under the action of tens of atmospheres The jets generate thrust.

The ignition circuit 12 is used to provide ignition energy to cause surface flashover of the spark plug semiconductor layer 4 , which specifically includes an ignition capacitor, a high voltage diode for isolation, a gas switch and a corresponding pre-trigger circuit. Among them, the capacity of the ignition capacitor is 0.1μF, and the charging voltage is 600V-1000V. According to the conduction frequency of the semiconductor switch in the pre-trigger circuit, the discharge frequency of the ignition capacitor is controlled, and then the operating frequency of the thruster is controlled. In order to ensure the consistency of the thruster output parameters, the maximum ignition frequency is 1Hz.

The main capacitor 9 adopts a low equivalent series impedance capacitor to reduce the energy loss caused by the internal impedance of the capacitor during the discharge process. In the present invention, the capacity of the main capacitor 9 is 1μF-4.5μF, the charging voltage is 1kV-3kV, which can be set within this range according to the working frequency, and the initial energy is 0.5J-20.25J.

The cathode 1 is made of brass material as the ground electrode, and is designed as an expanding nozzle with a half opening angle of 15°-30° and a length of 10mm-25mm. On the one hand, it is used as an electrode to form a discharge circuit to ensure the stable occurrence of discharge. On the other hand, it is used as a nozzle to guide the direction of the plasma jet, and an electromagnetic acceleration mechanism is introduced to increase the specific impulse and improve the overall efficiency of the thruster.

The high-performance spark plug 4 is installed near the plasma outlet of the cathode nozzle, and the tungsten electrode 2 is used as the high-voltage end of the spark plug, which has a large electron emission coefficient and good ablation resistance. Using the cathode 1 of the thruster as the low-voltage end of the spark plug can reduce the volume of the device while avoiding complex insulation structure settings.

Further, the semiconductor layer 4 of the spark plug is based on silicon carbide, mixed with zirconium dioxide, aluminum oxide and glass in a certain proportion, has a low water absorption rate and air absorption rate, and improves the traditional spark plug to a certain extent. The problem of failure due to surface area carbon increases the service life of the thruster. At the same time, surface discharge can occur at a DC voltage of 600V in vacuum to generate initial charged particles and stably trigger the thruster to work, which greatly reduces the requirements for insulation levels and simplifies the overall structure of the device.

The cathode connecting bolt 3 and the anode connecting bolt 8 can make the transmission line and the electrode closely connected, reduce the contact resistance between the electrode and the transmission line, make the circuit more compact, and improve energy utilization efficiency.

The propellant working medium 5 is made of solid polytetrafluoroethylene material, and is designed as a coaxial capillary installed between the anode 7 and the cathode nozzle 1, which saves the propellant working medium supply device, and is similar to the traditional pulse plasma thruster. Compared with that, under the action of discharge arc, the ionization rate of propellant molecules is higher. The thruster using PTFE as the propellant working fluid, compared with other gas-generating materials, can produce greater specific impulse and meta-impulse at a given deposition energy, and there is no carbonization on the surface, which can improve the thruster’s performance. service life. In the present invention, the structural parameters of the propellant working medium 5 can be changed according to actual needs. The propellant working medium 5 has a pipe diameter of 1 mm to 10 mm and a length of 9 mm to 20 mm.

The thruster fixing device adopts a plexiglass shell 6, and connects the cathode nozzle 1 and the anode 7 by threads, so that the tight connection of the thruster main body is realized, and it has reliability and stability.

The anode 7 is made of brass material as a high-voltage electrode, and is designed as a hollow cylinder, which can effectively reduce the overall mass of the device. In order to avoid the close contact between the end face of the electrode and the end face of the propellant working medium 5 caused by the processing accuracy or the huge pressure inside the plasma when the thruster is running, the anode 7 and the plexiglass shell 6 are assembled with threads and a certain margin is left , and can adapt to different capillary lengths by adjusting the connection length with the plexiglass shell 6 to achieve a tight fit.

The power processing unit 11 converts the bus voltage (generally 28V) of the satellite platform into the voltage required for the thruster to work and monitors it. In the present invention, the power processing unit has three outputs, which respectively convert the 28V satellite bus voltage into 1kV-3kV required for charging the main capacitor 9, 0-200V required for charging the capacitor bank in the pre-trigger circuit, and 0-200V required for charging the capacitor bank in the ignition circuit. 600V ~ 1000V required for charging.

Further, the power processing unit is connected to the main capacitor and the ignition capacitor through a high-voltage transmission line. The power processing unit can control the single pulse discharge energy and ignition energy by controlling the charging voltage of the main discharge capacitor and the charging voltage of the capacitor in the ignition circuit through the system.

Figure 2 is a typical waveform of the main discharge when the new pulsed plasma thruster based on capillary discharge is working. Among them, waveform 1 is the main discharge current waveform, and waveform 2 is the main discharge voltage waveform. After the ignition command is issued, surface flashover occurs on the spark plug semiconductor surface and initial charged particles are generated to cause arc discharge between the cathode and anode of the thruster. At this time, the plasma density in the arc is small, the conductivity is low, and the main voltage suddenly drops with the sudden drop of the arc resistance. As shown in Figure 2, the main voltage drop amplitude is U _b , and the arcing time is t ₁ . With the arc ablation of the propellant working fluid, the plasma fills the entire capillary cavity and ejects outward, and the plasma conductivity is at a high level and remains stable. At this time, the main discharge turns into a sinusoidal attenuation oscillation RLC discharge until the main capacitor The energy is completely released, and the duration of the RLC discharge is t ₂ .

The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand; Modifications are made to the recorded technical solutions, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical descriptions of the embodiments of the present invention.

Claims (10)

1. a kind of pulsed plasma thruster based on capillary discharging, which is characterized in that the thruster includes: at power supply Manage unit, semiconductor spark plug, firing circuit, main discharge circuit and propellant working medium；

Voltage needed for the power supply processing unit is used to be supplied to thruster work carries out the main capacitance in main discharge circuit It charges and powers to firing circuit；

The firing circuit makes semiconductor spark plug that creeping discharge generation initial charged particles occur for exporting high voltage pulse；

The initial charged particles that the semiconductor spark plug generates enter in propellant working medium, are generated by continuous ionization by collision Plasma；

The propellant working medium is capillary type, and with the generation of plasma, edge flashing shape occurs for propellant working medium surface At the electric discharge of main capacitance in main discharge circuit；

The main discharge circuit for the electric energy that power supply processing unit provides is stored and is transmitted, ablation propellant working medium simultaneously Accelerate plasma, main capacitance energy is converted into plasma kinetic energy, to form plasma jet, generates thrust.

2. thruster according to claim 1, which is characterized in that the thruster further include: cathode nozzle, anode and have Machine glass shell；

The cathode nozzle is for accelerating plasma；

The organic glass shell is for connecting cathode nozzle, anode and propellant working medium.

3. thruster according to claim 2, which is characterized in that the firing circuit includes: ignition capacitor, isolation use Kenetron, ignition switch and pre-trigger circuit；

The ignition capacitor high-voltage end is connect by isolation kenetron with ignition switch one end, low-pressure end and thruster Cathode nozzle is connected；

The pre-trigger circuit output pulse signal drive ignition switch generates ignition capacitor to semiconductor spark plug electric discharge Initial charged particles.

4. thruster according to claim 3, it is characterised in that: the propellant working medium uses solid polytetrafluor ethylene material Material；

The propellant working medium is coaxial capillary type, being capable of the change of the output parameter according to required for the space tasks of thruster The length and internal diameter of working medium；

The capillary inner diameter is 1mm~10mm, and length is 9mm~20mm.

5. thruster according to claim 3, it is characterised in that: the pre-trigger circuit includes capacitor group, semiconductor Switch, control circuit and pulse transformer；

Primary side of the capacitor group for pulse transformer is discharged, and exports high voltage pulse on pulse transformer pair side, is applied It is added in the filp-flop stage and low-pressure end of ignition switch and switches it on；

The control circuit is for being connected semiconductor switch.

6. thruster according to claim 1, which is characterized in that the material of the semiconductor spark plug semiconductor is to be carbonized Silicon is substrate, by zirconium dioxide, aluminum oxide, glass and silicon carbide with 17: 22: 12: 49 percent mass ratio sintering and At, the porosity 5%, water absorption rate 0.8%.

7. thruster according to claim 2, it is characterised in that: the cathode nozzle is divergent nozzle shape, cathode spray Mouth half angle angle is 15 °~30 °, and length is 10mm~25mm；

Screw assembly is used between the cathode nozzle and organic glass shell and is fitted close.

8. thruster according to claim 2, it is characterised in that: the anode be hollow cylinder shape, the anode with have Screw assembly is used between machine glass shell, and there are the allowances of 0.8-1.2mm to guarantee the cooperation between propellant working medium.

9. thruster according to claim 1, it is characterised in that: the thruster is worked with impulse form, work when institute The energy acceptor capacitance and charging voltage of consumption control, and working frequency is 0~1Hz, and pulse working time is 4~5 μ s.

10. thruster according to claim 1, it is characterised in that: the main capacitance capacity is the 1 μ F of μ F~4.5, charging electricity Pressure is 1kV~3kV, and primary power is 0.5J~20.25J.