CN108301997A - Pulsed plasma thruster based on Z-PINCH no-spark plugs - Google Patents

Abstract

A kind of pulsed plasma thruster based on Z PINCH no-spark plugs includes the anode of the cathode of the tray type structure that is set in turn between pedestal and outer insulator, solid propellant and pyramidal structure, wherein：Cathode and anode are respectively arranged at the both ends of solid propellant, and outer insulator is placed on the outside of solid propellant and is connected with pedestal.The present invention is not necessarily to spark plug auxiliary firing, realizes propellant fire and electric discharge integration, reduces ignition voltage；Propellant feed is carried out without spring, it is simple in structure without any movable part；Unique structure design can effectively improve the utilization ratio of propellant, push away work(and compare higher；Size is not particularly limited.

Description

Pulse plasma thruster based on Z-PINCH without spark plug

technical field

The invention relates to a technology in the field of space electric propulsion technology and electric thruster design, in particular to a pulsed plasma thruster based on Z-PINCH without spark plug.

Background technique

The pulse plasma thruster uses pulse discharge to ablate, decompose, and ionize the propellant to make it into plasma. Traditional pulsed plasma thrusters usually use solid polytetrafluoroethylene as the propellant combined with spring supply, and some scholars have studied gas and liquid propellants. From a structural point of view, the traditional pulsed plasma thruster uses parallel plate electrodes combined with a spark plug to achieve ignition and pulsed arc generation. Some people have also proposed a coaxial pulsed plasma thruster, but the principle of ignition and thrust is that the plasma is in the magnetic field and Under the joint action of the discharge current, it is accelerated by the generalized Lorentz force to generate thrust. When the traditional parallel plate electrode pulse plasma thruster works, the energy storage capacitor is first charged to the required voltage, and then the semiconductor spark plug is ignited, the capacitor discharges along the surface of the working medium PTFE, the current is formed on the working medium surface, and the heat flow will gather Molecules on the surface of tetrafluoroethylene depolymerize, split, and ionize. Then, under the joint action of generalized Lorentz force and pneumatic pressure, the plasma is accelerated, and the plasma is expanded and ejected to generate thrust. After the capacitor is discharged, the thruster stops working or enters the next cycle. Due to the hysteresis of heat transfer, part of the propellant will still be sublimated into gas after each discharge but cannot be ionized, resulting in a very low utilization rate of the propellant.

Contents of the invention

The present invention aims at defects such as existing pulsed plasma thrusters relying on spark plugs, resulting in many structural components that are too large in size, increasing potential safety hazards, and low propellant utilization, and proposes a pulsed plasma thruster based on Z-PINCH without spark plugs , no need for spark plug to assist ignition, realize the integration of propellant ignition and discharge, and reduce the ignition voltage; no spring for propellant supply, no moving parts, simple structure; unique structural design can effectively improve the utilization efficiency of propellant, Higher thrust-to-power ratio; no special restrictions on size.

The present invention is achieved through the following technical solutions:

The present invention comprises a disc structure cathode, a solid propellant and an anode of a conical structure arranged between the base and the outer layer insulator in sequence, wherein: the cathode and the anode are respectively arranged at two ends of the solid propellant, and the outer layer insulator covers Placed on the exterior of the solid propellant and attached to the base.

The cathode is preferably a disc structure made of metal copper, with a small circular hole on the top for connecting to an external circuit.

The anode is preferably a conical structure made of metal copper, and a small circular hole is provided at the bottom for connecting to an external circuit.

The solid propellant is preferably a cylindrical cavity structure, more preferably made of polytetrafluoroethylene impregnated with conductive material.

The base and the outer insulator are preferably made of polycarbonate.

technical effect

Compared with the prior art, the present invention charges the positive and negative poles of the thruster to a given voltage. On the surface of the propellant, a cylindrical current sheet is rapidly formed, ablates the polytetrafluoroethylene, accelerates the ablation product in the radial direction, and the current starts to flow between the two poles. flow between electrodes. Initially, the current is distributed on the surface of the insulator, forming a cylindrical current sheet. The current sheet forms at the largest radius of the cavity, since this is where the loop impedance is the smallest. As the current increases, a magnetic field is generated on the outside of the current sheet. The magnetic field interacts with the current sheet to produce an electromagnetic force that radiates inward. This force causes the current sheet to collapse toward the center of the cavity, but instead of moving toward the center in a completely cylindrical shape, the current sheet tilts, a phenomenon known as the zipper effect. Under the action of the current sheet, the propellant is initially accelerated radially; when the current sheet is fully contracted, the presence of small holes leads to a large axial pressure gradient. As a result, the plasma is ejected with acceleration along the axial direction. The plasma is squeezed and expanded under the action of radial force, and spreads along the axial direction.

Description of drawings

Fig. 1, Fig. 2 are overall structural representations of the present invention;

Fig. 3 is a schematic diagram of the outer layer insulator described in the present invention;

Fig. 4 is the cathode schematic diagram described in the present invention;

Fig. 5 is a schematic diagram of the propulsion chamber described in the present invention;

Fig. 6 is a schematic diagram of the anode described in the present invention;

Fig. 7 is a schematic diagram of the base described in the present invention;

Fig. 8 and Fig. 9 are the effect schematic diagram of embodiment;

In the figure: 1 outer insulator, 2 cathode, 3 solid propellant, 4 anode, 5 base.

Detailed ways

As shown in Figure 1 and Figure 2, it is a new type of pulsed plasma propulsion device based on the Z-PINCH principle without spark plugs involved in this embodiment, including: an outer layer insulator 1, a cathode 2, and a solid propulsion device connected sequentially from top to bottom. Agent 3, anode 4 and base 5, wherein: the circular small hole on the top of cathode 2 is used to connect to an external circuit. The circular small hole at the bottom of the anode 4 is used for connecting an external circuit.

As shown in Figures 3 and 7, the outer insulator 1 and the base 6 are both made of polycarbonate, which has flame retardancy, wear resistance and oxidation resistance.

As shown in Figures 4 and 6, both the cathode 2 and the anode 4 are made of metal copper, which has good electrical conductivity, high temperature resistance and high melting point. There is a small hole in the middle of the cathode 2, and the plasma generated after the solid propellant 3 is ablated is ejected from the hole. The upper part of the anode 4 is a cone, which facilitates the generation of radial force when the current sheet is formed.

As shown in FIG. 5 , the solid propellant 3 is made of polytetrafluoroethylene, and the polytetrafluoroethylene is infiltrated with a specific conductive material. PTFE has the characteristics of high temperature resistance, corrosion resistance and insulation, and generates plasma after ablation. The purpose of adopting the cylindrical discharge chamber is to maximize the use of space for propellant storage under the condition of given size.

This embodiment works in the following way: A hollow cylindrical polytetrafluoroethylene is placed between the positive and negative electrodes. On the surface of the propellant, a cylindrical current sheet is formed rapidly, ablating the PTFE, accelerating the ablation products radially, and the current begins to flow between the two electrodes. Initially, the current is distributed on the surface of the insulator, forming a cylindrical current sheet. The current sheet forms at the largest radius of the cavity, since this is where the loop impedance is the smallest. As the current increases, a magnetic field is generated on the outside of the current sheet. The magnetic field interacts with the current sheet to generate an electromagnetic force that radiates inward. This force causes the current sheet to collapse toward the center of the cavity, but instead of moving toward the center in a completely cylindrical shape, the current sheet tilts, a phenomenon known as the zipper effect. Under the action of the current sheet, the propellant is initially accelerated radially; when the current sheet is fully contracted, the presence of small holes leads to a large axial pressure gradient. Therefore, the plasma is ejected with acceleration along the axial direction. The plasma is compressed and expanded under the action of radial force, and spreads along the axial direction.

According to the thruster described in the invention, an experimental scheme is designed to verify its performance, and the specific steps are as follows:

Step 1) Fix the thruster on the thrust measuring device in the vacuum cabin, adjust the position of the motion platform in the cabin, so as to monitor the working condition of the thruster through the observation window on the bulkhead;

Step 2) debugging and static calibration of the thrust measuring device;

Step 3) electrically positioning the thrust measuring device, and evacuating to the required vacuum degree;

Step 4) Release the electric positioning of the thrust measuring device, observe the indication value of the force display window on the measurement and control instrument, and prepare for the experiment after it is basically stable;

Step 5) Turn on the thruster power supply system (including the main capacitor charging power supply and the ignition system power supply), and simultaneously turn on the data acquisition system power supply, and record the zero point of the current thrust measuring device;

Step 6) Thruster ignition experiment, the data acquisition system records the thrust measurement data.

When voltage is applied to the yin and yang stages of the thruster, as shown in Figure 8, the thruster starts to work.

As shown in Figure 9, it is the discharge characteristic of a pulse during the stable operation of the thruster. According to the U-I curve, it can be seen that the initial voltage is 20V, and the ignition voltage is 480V. The duration of the charging process is 1ms. At this time, the current increases, the maximum value is 24A, and then the current decreases slowly. The duration of the entire discharge process is 1.04ms. It can be calculated from the figure that the operating power of the new thruster is 4.8W.

Experimental results show that the thruster can work and meet the design requirements initially. The thrust power ratio is 17.83μN/W, which is larger than that of the traditional pulsed plasma thruster. The above specific implementation can be partially adjusted in different ways by those skilled in the art without departing from the principle and purpose of the present invention. The scope of protection of the present invention is subject to the claims and is not limited by the above specific implementation. Each implementation within the scope is bound by the invention.

Claims (6)

1. A pulse plasma thruster without spark plug based on Z-PINCH, is characterized in that, comprises the anode of the negative electrode of the disk structure, solid propellant and conical structure that are arranged successively between base and outer layer insulator, Wherein: the cathode and the anode are respectively arranged at the two ends of the solid propellant, and the outer insulator is sleeved on the outside of the solid propellant and connected with the base. 2. The pulsed plasma thruster according to claim 1, wherein the cathode is a disc structure made of metal copper, and the top is provided with a small circular hole for connecting to an external circuit. 3. The pulsed plasma thruster according to claim 1, characterized in that, the anode is a conical structure made of metal copper, and the bottom is provided with a small circular hole for connecting to an external circuit. 4. The pulsed plasma thruster according to claim 1, wherein the solid propellant has a cylindrical cavity structure. 5. The pulsed plasma thruster according to claim 4, wherein the solid propellant is made of polytetrafluoroethylene impregnated with conductive material. 6. The pulsed plasma thruster according to claim 1, wherein the base and the outer layer insulator are made of polycarbonate.