CN110630460B

CN110630460B - Segmented anode high specific impulse pulse plasma thruster

Info

Publication number: CN110630460B
Application number: CN201910986475.5A
Authority: CN
Inventors: 汤海滨; 许舒婷; 章喆; 张尊; 曹晋滨
Original assignee: Beihang University
Current assignee: Beihang University
Priority date: 2019-10-17
Filing date: 2019-10-17
Publication date: 2020-08-14
Anticipated expiration: 2039-10-17
Also published as: CN110630460A

Abstract

The invention relates to a segmented anode high specific impulse pulse plasma thruster, which comprises a cathode, an anode, an electric arc, a spark plug, a propellant, an energy storage capacitor, a power supply and a ground, wherein the cathode is connected with the anode; the anode comprises an anode body and an insulating block, wherein the anode body is divided into an upstream anode and a downstream anode by the insulating block; the power supply charges the energy storage capacitor, and two ends of the energy storage capacitor are respectively connected with the cathode and the upstream anode; the spark plug generates an electron-triggered arc that arcs from the cathode to the anode along the propellant surface; the lead is connected with the upstream anode and the downstream anode; plasma obtained by the ionization of the surface of the propellant is accelerated and sprayed out under the action of electromagnetic force of the upstream anode and the downstream anode to form thrust. The invention realizes the limitation of electric arc and the improvement of local current density by adopting the segmented anode; the insulating block is arranged in front of the arc attachment point, so that the migration phenomenon of the arc is prevented, the high temperature and the high current density on the surface of the propellant can be continuously maintained, and the thrust, the specific impulse, the ablation amount and the efficiency of the thruster are improved.

Description

Segmented anode high specific impulse pulse plasma thruster

Technical Field

The invention belongs to the field of electric propulsion plasma application, and relates to a segmented anode high specific impulse pulse plasma thruster.

Background

The electric propulsion is an advanced propulsion mode which utilizes electric energy to directly heat the propellant or utilizes electromagnetic action to ionize and accelerate the propellant so as to obtain propulsion power, has higher specific impulse, thrust and efficiency, and has wide application prospect in space tasks of orbit control, deep space exploration, interstellar navigation and the like of large-scale spacecrafts.

The pulsed plasma thruster is one of electromagnetic thrusters, and is widely applied to a main propulsion system of a satellite and a deep space probe at present. The optimization of performance parameters of the pulse plasma thruster, including parameters such as specific impulse, efficiency and thrust, is a fundamental task of engine design, and has important significance for expanding future application of the pulse plasma thruster. The optimization of the electrode structure of the thruster is a common means, but the optimization effect is not ideal, and no reasonable electrode optimization scheme exists at present because the discharge time of the pulsed plasma thruster is short (10 mus) and the acceleration mechanism is unclear.

Disclosure of Invention

The invention aims to design a segmented anode high specific impulse pulse plasma thruster, which can realize the optimization of performance parameters of the thruster, such as specific impulse rise, ablation amount increase, thrust increase, efficiency increase and the like.

In order to realize the purpose of the invention, the following technical scheme is provided:

the utility model provides a high specific impulse pulse plasma thrustor of segmentation positive pole, includes negative pole, positive pole, electric arc, spark plug, propellant, energy storage capacitor, power, ground, its characterized in that: the anode comprises an anode body and an insulating block, wherein the anode body is divided into an upstream anode and a downstream anode by the insulating block; the power supply charges the energy storage capacitor, and two ends of the energy storage capacitor are respectively connected with the cathode and the upstream anode; the spark plug generates an electron-triggered arc that arcs from the cathode to the anode along the propellant surface; the lead is connected with the upstream anode and the downstream anode; plasma obtained by the ionization of the surface of the propellant is accelerated and sprayed out under the action of electromagnetic force of the upstream anode and the downstream anode to form thrust.

Further, the insulating block is located 4mm from the propellant surface in front of the arc attachment point.

Furthermore, the insulating block is made of micro quartz crystal ceramic and has the length of 2 mm.

The invention has the advantages that:

1. based on a large number of experimental data tests, it was found that the distribution of ions and electrons in the pulse discharge ionization mode is asymmetric, that is, the current density distribution is asymmetric, as shown in fig. 1, it is obvious that the current density near the anode is much higher than that near the cathode, which means that the electric field distribution and the arc existence mode of the conventional symmetric electrode are unreasonable. In view of the above, the present invention designs a segmented anode having a completely asymmetric electric field structure with a continuous parallel plate cathode, which can change the arc morphology of the propellant surface, increase the current density near the anode, and the segmented downstream electric field can also enhance the confinement of plasma.

2. The traditional symmetrically distributed electrodes have the problems of arc divergence and non-centralized ionization positions. According to the invention, the ceramic insulating block is designed at the upstream of the anode, so that the restraint of the arc morphology is realized, the arc is ensured not to move downstream due to thermal expansion, and the current density at the anode end is further enhanced.

3. According to the invention, the segmented anode structure is obtained through the insulating block arranged at the upstream of the anode, and better plasma convergence is realized. The configuration using segmented anodes maintains the downstream electric field between the electrodes to achieve better plasma pinch (compared to short electrodes) while still simulating a short electrode configuration to limit the divergence of the upstream arc.

4. The position of the insulating block is designed in a key way, if the position is too close to the surface of the propellant, electric arcs can directly jump over the insulating block and migrate to a downstream anode to discharge, and the performance of the thruster is influenced; too far from the propellant surface can cause thermal expansion of the arc away from the propellant, reducing ionization efficiency. The variation trend of the electronic energy peak value is calculated through experimental data analysis, so that the optimal position of the insulating block is obtained, the insulating block is 4mm away from the surface of the propellant and is just designed in front of an electric arc attachment point, the migration phenomenon of the electric arc is prevented, and the high temperature and the high current density of the surface of the propellant can be continuously maintained.

5. The invention adopts an asymmetric design, and abandons the addition of an insulating block at the cathode end. The cathode mainly serves to supply electrons, which have a mass of 0.05% of that of the ions, and to assemble the spark plug, so that the ions are much larger than the electrons in contribution to the thrust. Moreover, the assembly of the insulator block on the cathode can affect the operation of the spark plug, resulting in electron avalanche obstruction. Therefore, the invention adopts an asymmetric design, abandons the addition of an insulating block at the cathode end and only makes a sectional structural design on the anode.

Drawings

FIG. 1 is a conventional symmetrical, non-segmented, inter-electrode current density distribution cloud;

FIG. 2 is a schematic diagram of a segmented anode high specific impulse pulsed plasma thruster;

fig. 3 is a comparison result of thrust performance of the segmented anode high specific impulse pulsed plasma thruster and the conventional symmetric parallel plate pulsed plasma thruster.

In the figure: 1. a cathode; 2. an electric arc; 3. a spark plug; 4. an upstream anode; 5. a wire; 6. an insulating block; 7. a downstream anode; 8. a propellant; 9. an energy storage capacitor; 10. a power source; 11. and (3) ground.

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings.

The invention provides a schematic diagram of a segmented anode high specific impulse pulse plasma thruster, which is shown in figure 2 and comprises a cathode 1, an electric arc 2, a spark plug 3, an upstream anode 4, a lead 5, an insulating block 6, a downstream anode 7, a propellant 8, an energy storage capacitor 9, a power supply 10 and a ground 11. A power supply 10 loads 2000V high voltage on an energy storage capacitor 9, wherein the energy storage capacitor 9 is an oil-immersed capacitor with the capacitance value of 10 mu F; the two ends of the energy storage capacitor 9 are connected with the cathode 1 and the upstream anode 4; electrons are generated through the spark plug 3, electric arcs 2 at two ends of the cathode and the anode are triggered, and the electric arcs 2 ablate and ionize plasmas along the surface of the propellant 8; the lead 5 is connected with the upstream anode 4 and the downstream anode 7, and an insulating block 6 is arranged between the upstream anode 4 and the downstream anode 7 to prevent the arc striking area on the surface of the upstream anode 4 from excessively dispersing the current density; finally, plasma obtained by ionization of the surface of the propellant 8 is accelerated and sprayed out under the action of the electromagnetic force of the upstream anode 4 and the downstream anode 7 to form thrust.

The pulse plasma thruster has a discharge gap of 15-20mm, a discharge voltage of 1-2kV, and can generate arc discharge along the wall surface of propellant in the presence of propellant, wherein the obtained arc temperature is over 1200K, and the arc width is larger than 1 mm. Under the action of higher surface temperature, the electric arc can be separated from the wall surface due to thermal expansion to generate a migration phenomenon, and the electric arc is influenced to ionize the propellant. Therefore, an insulating block is arranged at the anode position to limit the thermal expansion of the arc. For the position of the insulating block, if the position is too close to the surface of the propellant, an electric arc can directly jump over the insulating block and migrate to a downstream anode for discharging, and the performance of the thruster is influenced; too far from the propellant surface can cause thermal expansion of the arc away from the propellant, reducing ionization efficiency. The change trend of the electronic energy peak value is analyzed and calculated through spectrum experiment data, the optimal insulating block position is obtained, the insulating block is 4mm away from the surface of the propellant and is just designed in front of an electric arc attachment point, the migration phenomenon of the electric arc is prevented, and the high temperature and the high current density of the surface of the propellant can be continuously maintained.

The insulating block is made of micro quartz crystal ceramic and has a length of 2 mm. The width of the discharge arc along the wall surface of the propellant is usually 1mm, and the width of the insulating block is more than 1mm, so that the arc is prevented from directly jumping over the insulating block and continuously migrating, and the insulating block structure is ensured to play a role in limiting the arc.

Fig. 3 compares the main performance parameter, the unit impulse, of the conventional pulsed plasma thruster and the segmented anode high specific impulse pulsed plasma thruster after the design improvement. Seven discharge energy levels of 5J-20J are selected for comparison, and the impulse generated by the segmented anode high specific impulse plasma thruster is higher than that of the traditional impulse plasma thruster in each energy level. In the magnitude of 20J, the impulse generated by the segmented anode high specific impulse plasma thruster is 28% higher than that of the traditional impulse plasma thruster. The proposal of the segmented anode structure proves that the optimization of the performance of the pulse plasma thruster is realized.

The foregoing are only some embodiments of the invention. It will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept thereof, and these changes and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. The utility model provides a high specific impulse pulse plasma thrustor of segmentation positive pole, includes negative pole, positive pole, electric arc, spark plug, propellant, energy storage capacitor, power, ground, its characterized in that: the anode comprises an anode body and an insulating block, wherein the anode body is divided into an upstream anode and a downstream anode by the insulating block; the power supply charges the energy storage capacitor, and two ends of the energy storage capacitor are respectively connected with the cathode and the upstream anode to form a segmented anode which has a completely asymmetric electric field structure with the continuous parallel plate cathode; the spark plug generates an electron-triggered arc that arcs from the cathode to the anode along the propellant surface; the lead is connected with the upstream anode and the downstream anode; plasma obtained by the ionization of the surface of the propellant is accelerated and sprayed out under the action of electromagnetic force of the upstream anode and the downstream anode to form thrust; the insulating block is 4mm away from the surface of the propellant and is positioned in front of the arc attachment point; the insulating block is made of micro quartz crystal ceramic and has a length of 2 mm.