Micro cathode arc thrust system

Abstract

The invention discloses a micro cathode arc thrust system, and relates to the technical field of satellite micro propulsion, the system comprises a micro cathode arc thruster, a heating unit and a heating control unit; a cathode working medium of the micro cathode arc thruster is liquid metal; the heating unit is arranged on a cathode pipeline of the micro cathode arc thruster; the heating unit is connected with the capacitor and the heating control unit; the heating control unit comprises a temperature measuring subunit, a first control subunit and a second control subunit; the hot end of the temperature measurement subunit is arranged on a cathode pipeline of the micro cathode arc thruster, the cold end of the temperature measurement subunit is arranged in the environment, and the temperature measurement subunit is connected with the first control subunit and the second control subunit; the first control subunit is connected with the heating unit and the power supply. The service life of the micro-cathode arc thruster can be prolonged, the total impulse of the micro-cathode arc thruster can be increased, the energy consumption loss of a micro-cathode arc thrust system is reduced, and meanwhile the whole thrust system can be more concise and portable.

Description

Technical Field

[0001] The present application relates to the field of satellite micro-propulsion technology, and in particular to a micro cathode arc thrust system. Background Art

[0002] The microcathode arc thrusters in traditional microcathode arc thrust systems face a series of challenges in practical applications, such as uneven cathode ablation, limited fluid carrying capacity in a single space mission, and excessive energy consumption of protective resistors. These problems shorten the life of the thrusters, reduce their total impulse, and cause huge energy losses in the protective resistors during discharge. Summary of the invention

[0003] The purpose of this application is to provide a micro-cathode arc thrust system, which can improve the service life and total impulse of the micro-cathode arc thruster, reduce the energy loss of the micro-cathode arc thrust system, and make the entire thrust system more concise and lightweight.

[0004] To achieve the above objectives, this application provides the following solutions:

[0005] In a first aspect, the present application provides a micro cathode arc thrust system, comprising: a power supply, a capacitor and a resistor, a micro cathode arc thruster, a heating unit and a heating control unit; the cathode working fluid of the micro cathode arc thruster is liquid metal;

[0006] The heating unit is arranged on the cathode pipe of the micro cathode arc thruster; one end of the heating unit is connected to the capacitor, and the other end of the heating unit is connected to the heating control unit;

[0007] The heating control unit comprises: a temperature measuring subunit, a first control subunit and a second control subunit;

[0008] The hot end of the temperature measuring subunit is arranged on the cathode pipeline of the micro cathode arc thruster, the cold end of the temperature measuring subunit is arranged in the environment, and the output end of the temperature measuring subunit is connected to the first end of the first control subunit and the first end of the second control subunit;

[0009] The second end of the first control subunit is connected to the other end of the heating unit, and the third end of the first control subunit is connected to the positive electrode of the power supply;

[0010] The second end of the second control subunit is connected to the resistor, and the third end of the second control subunit is connected to the positive electrode of the power supply.

[0011] Optionally, the temperature measurement subunit includes: a temperature difference sensing device and a voltage amplifier;

[0012] The hot end of the temperature difference sensing device is arranged on the cathode pipe of the micro cathode arc thruster, the cold end of the temperature difference sensing device is arranged in the environment, and the output end of the temperature difference sensing device is connected to the input end of the voltage amplifier;

[0013] The output end of the voltage amplifier is connected to the first end of the first control subunit and the first end of the second control subunit.

[0014] Optionally, the first control subunit includes: a NOT gate and a first switch tube;

[0015] One end of the NOT gate is connected to the output end of the temperature measuring sub-unit, and the other end of the NOT gate is connected to the gate of the first switch tube;

[0016] The source of the first switch tube is connected to the other end of the heating unit, and the drain of the first switch tube is connected to the positive electrode of the power supply.

[0017] Optionally, the first control subunit is a second switch tube;

[0018] The drain of the second switch tube is connected to the positive electrode of the power supply; the gate of the second switch tube is connected to the temperature measuring subunit; and the source of the second switch tube is connected to the resistor.

[0019] Optionally, the liquid metal is gallium-based liquid metal.

[0020] Optionally, the heating unit is an electric heating plate.

[0021] Optionally, the temperature difference sensing device is a thermocouple.

[0022] Optionally, the first switch tube and the second switch tube are both IGBTs.

[0023] Optionally, the thermocouple is a K-type nickel-chromium-nickel-silicon thermocouple.

[0024] Optionally, the thermocouple is a T-type copper-copper-nickel thermocouple.

[0025] According to the specific embodiments provided in this application, this application has the following technical effects:

[0026] The present application provides a micro cathode arc thrust system. In the present application, liquid metal is used as the cathode working fluid of the micro cathode arc thruster, so that the uneven cathode ablation can be reduced and the service life and total impulse of the micro cathode arc thruster can be improved; a heating unit is provided to replace the protective resistor in the traditional micro cathode arc thrust system, so that the energy lost by the protective resistor in the traditional thrust system is fully utilized to keep the cathode working fluid in a liquid state in the low temperature environment of the universe, and further avoid adding an additional heating system, so that the structure of the entire micro cathode arc thrust system can be made simpler and lighter; the heating unit and the heating control unit cooperate to make the heat generated by the heating unit used to maintain the liquid characteristics of the thruster cathode working fluid, so that the energy loss of the micro cathode arc thrust system can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is a structural schematic diagram of a micro cathode arc thrust system in one embodiment of the present application;

[0029] Figure 2 Schematic diagram of the structure of a traditional micro cathode arc thrust system in one embodiment of the present application. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0031] In order to make the above-mentioned objects, features and advantages of the present application more obvious and easy to understand, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0032] In an exemplary embodiment, the present application provides a micro-cathode arc thrust system, which includes: a power supply, a capacitor, a resistor, a micro-cathode arc thruster, a heating unit and a heating control unit; the cathode working fluid of the micro-cathode arc thruster is liquid metal.

[0033] The liquid metal in the present application may be a gallium-based liquid metal having a melting point of 29.8°C.

[0034] Wherein, the heating unit is arranged on the cathode pipe of the micro cathode arc thruster; one end of the heating unit is connected to the capacitor, and the other end of the heating unit is connected to the heating control unit.

[0035] The heating unit in the present application may be an electric heating plate.

[0036] The heating control unit includes: a temperature measuring subunit, a first control subunit and a second control subunit.

[0037] The hot end of the temperature measuring subunit is arranged on the cathode pipe of the micro cathode arc thruster, the cold end of the temperature measuring subunit is arranged in the environment, the output end of the temperature measuring subunit is connected to the first end of the first control subunit and the first end of the second control subunit, and the temperature measuring subunit is used to detect the temperature of the cathode working fluid of the micro cathode arc thruster.

[0038] The second end of the first control subunit is connected to the other end of the heating unit, the third end of the first control subunit is connected to the positive pole of the power supply, and the first control subunit is used to control the working state of the heating unit according to the output of the temperature measuring subunit.

[0039] The second end of the second control subunit is connected to the resistor, the third end of the second control subunit is connected to the positive pole of the power supply, and the second control subunit is used to ensure the normal operation of the micro cathode arc thrust system according to the output of the temperature measuring subunit.

[0040] In another exemplary embodiment of the present application, the temperature measurement subunit includes: a temperature difference sensing device and a voltage amplifier.

[0041] Specifically, the hot end of the temperature difference sensing device is arranged on the cathode pipe of the micro cathode arc thruster, the cold end of the temperature difference sensing device is arranged in the environment, the output end of the temperature difference sensing device is connected to the input end of the voltage amplifier, and the output end of the voltage amplifier is connected to the first end of the first control subunit and the first end of the second control subunit.

[0042] The temperature difference sensing device in the present application can be a thermocouple, such as a K-type nickel-chromium-nickel-silicon thermocouple with a temperature measurement range of -200°C to 1372°C or a T-type copper-copper-nickel thermocouple with a temperature measurement range of -200°C to 400°C.

[0043] The working principle of the thermocouple in the present application is: when there is a certain temperature difference between the hot end and the cold end of the thermocouple, the thermocouple outputs a high-level signal, otherwise it outputs a low-level signal.

[0044] In another exemplary embodiment of the present application, the first control subunit includes: a NOT gate and a first switch tube.

[0045] Specifically, one end of the NOT gate is connected to the output end of the temperature measuring subunit, and the other end of the NOT gate is connected to the gate of the first switch tube. The source of the first switch tube is connected to the other end of the heating unit, and the drain of the first switch tube is connected to the positive electrode of the power supply. In practical applications, the first switch tube can be an IGBT.

[0046] In another exemplary embodiment of the present application, the first control subunit is a second switch tube.

[0047] Specifically, the drain of the second switch tube is connected to the positive electrode of the power supply; the gate of the second switch tube is connected to the temperature measuring subunit; the source of the second switch tube is connected to the resistor. In practical applications, the second switch tube can be an IGBT.

[0048] In another exemplary embodiment of the present application, in order to better illustrate the micro cathode arc thrust system provided by the present application, a specific example is given below for illustration.

[0049] Traditional micro cathode arc thrust system such as Figure 2 As shown, the cathode working fluid of the micro-cathode arc is solid metal, so there are problems such as uneven cathode ablation of the cathode arc thruster and limited amount of working fluid carried in a single space mission. Therefore, the present application adopts liquid metal as the cathode working fluid of the micro-cathode arc thruster. This metal can remain liquid at extremely low temperatures (about 29.8°C), thereby reducing uneven cathode ablation and increasing the service life and total impulse of the micro-cathode arc thruster. However, in space, the temperature is usually around -270°C. In order to keep the liquid metal as the cathode working fluid in liquid state, a heating system needs to be introduced.

[0050] In order to avoid introducing an additional heating system that would increase the complexity and weight of the entire thrust system, the present application improves the circuit structure of the traditional micro cathode arc propulsion system. Figure 2 As shown in the figure, the protection resistor in the traditional micro-cathode arc thrust system is connected in series between the DC power supply anode and the capacitor to prevent the large current formed by the rapid disconnection of the IGBT switch during the thruster pulse discharge from damaging the DC power supply. However, the protection resistor will generate a lot of heat due to the passage of large current in this process. Therefore, the present application uses an electric heating plate to replace the protection resistor in series between the power supply and the capacitor, such as Figure 1 As shown, this electric heating plate is installed on the cathode pipe of the micro-cathode arc thruster, and this part of heat is used to heat the cathode working medium of the micro-cathode arc.

[0051] Furthermore, in order to prevent the electric heating plate from continuously heating and causing the cathode working fluid of the micro-cathode arc to overheat, resulting in its evaporation and loss, a thermocouple is used as a monitoring system for the temperature of the cathode working fluid of the micro-cathode arc to regulate the working state of the electric heating plate so that the cathode working fluid remains in a liquid state.

[0052] According to the working principle of thermocouple, the thermocouple is set Figure 1 In the micro cathode arc thrust system shown, a NOT gate, IGBT① (corresponding to the first switch tube) and IGBT② (corresponding to the second switch tube) are provided to jointly realize the regulation of the working state of the electric heating plate. Specifically, the cold end of the thermocouple is placed in the environment, and the hot end is placed on the cathode pipe of the micro cathode arc thruster. When the cathode pipe temperature of the micro cathode arc thruster is lower than the melting point of the cathode working fluid, the thermocouple outputs a low level. After the NOT gate is applied, IGBT① is turned on and IGBT② is turned off. The electric heating plate works, generating heat while protecting the circuit. The capacitor charging path is as follows: Figure 1 As shown in the loop ② formed by the red arrow in the figure; when the cathode pipe temperature of the micro cathode arc thruster is higher than the melting point of the cathode working fluid, the thermocouple outputs a high level. After the NOT gate is activated, IGBT ① is disconnected and IGBT ② is turned on. The electric heating plate does not work, and the capacitor charging path is as follows Figure 1 The blue arrow in the circuit ① shows the branch resistance, which plays a role in protecting the circuit. The specific value can be determined according to the discharge condition of the micro cathode arc thruster. However, if it is necessary to achieve extremely regular timing control and reduce the influence on the discharge characteristics of the micro cathode arc thruster, the branch resistance should be Figure 2 The protection resistor values ​​in the conventional micro-cathode arc thrust system shown are the same.

[0053] Further, the output level of the thermocouple may not be sufficient to stimulate the on and off states of the IGBT element, so a voltage amplifier needs to be added to the circuit, such as Figure 1 As shown, it is used to activate the working state of IGBT① and IGBT②.

[0054] This application has the following advantages over the prior art:

[0055] (1) Liquid metal is used as the cathode working fluid of the micro cathode arc thruster, which solves the problems of uneven cathode ablation of the cathode arc thruster in the prior art and the limited amount of working fluid carried in a single space mission, thereby improving the service life and total impulse of the micro cathode arc thruster.

[0056] (2) In the present application, the liquid metal can remain in liquid state at extremely low temperatures (about 29.8°C). However, in space, the temperature is usually around -270°C. In order to keep the liquid metal as the cathode working fluid in liquid state, a heating system needs to be introduced. The present application adds a heating unit instead of Figure 2The protective resistor in the traditional micro cathode arc thrust system shown in the figure effectively utilizes the heat generated by the large current, maintains the liquid characteristics of the cathode working fluid, and realizes the sufficient supply and self-repair characteristics of the cathode working fluid by ensuring the fluidity of the liquid metal, avoiding the addition of an additional heating system, thereby making the structure of the entire micro cathode arc thrust system more concise and lightweight, and ensuring the reliability of the micro cathode arc thrust system working in a low temperature environment.

[0057] (3) The present application uses a thermocouple as a temperature monitoring system to achieve regulation of the working state of the heating unit, which can not only keep the cathode working fluid in a liquid state, but also prevent the heating unit from continuously heating the cathode working fluid so as to overheat and cause the cathode working fluid to evaporate and form losses.

[0058] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] This article uses specific examples to illustrate the principles and implementation methods of this application. The description of the above embodiments is only used to help understand the method and core ideas of this application. At the same time, for those skilled in the art, according to the ideas of this application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting this application.

Claims

1. A micro cathode arc thrust system, the micro cathode arc thrust system comprising: power supply, capacitor and resistor, characterized in that the micro cathode arc thrust system further comprises: a micro cathode arc thruster, a heating unit and a heating control unit; the cathode working fluid of the micro cathode arc thruster is liquid metal; The heating unit is arranged on the cathode pipe of the micro cathode arc thruster; one end of the heating unit is connected to the capacitor, and the other end of the heating unit is connected to the heating control unit; The heating control unit comprises: a temperature measuring subunit, a first control subunit and a second control subunit; The hot end of the temperature measuring subunit is arranged on the cathode pipeline of the micro cathode arc thruster, the cold end of the temperature measuring subunit is arranged in the environment, and the output end of the temperature measuring subunit is connected to the first end of the first control subunit and the first end of the second control subunit; The second end of the first control subunit is connected to the other end of the heating unit, and the third end of the first control subunit is connected to the positive electrode of the power supply; The second end of the second control subunit is connected to the resistor, and the third end of the second control subunit is connected to the positive electrode of the power supply.

2. The micro cathode arc thrust system according to claim 1, characterized in that: The temperature measurement subunit includes: a temperature difference sensing device and a voltage amplifier; The hot end of the temperature difference sensing device is arranged on the cathode pipe of the micro cathode arc thruster, the cold end of the temperature difference sensing device is arranged in the environment, and the output end of the temperature difference sensing device is connected to the input end of the voltage amplifier; The output end of the voltage amplifier is connected to the first end of the first control subunit and the first end of the second control subunit.

3. The micro cathode arc thrust system according to claim 1, characterized in that: The first control subunit includes: a NOT gate and a first switch tube; One end of the NOT gate is connected to the output end of the temperature measuring sub-unit, and the other end of the NOT gate is connected to the gate of the first switch tube; The source of the first switch tube is connected to the other end of the heating unit, and the drain of the first switch tube is connected to the positive electrode of the power supply.

4. The micro cathode arc thrust system according to claim 1, characterized in that: The first control subunit is a second switch tube; The drain of the second switch tube is connected to the positive electrode of the power supply; the gate of the second switch tube is connected to the temperature measuring subunit; and the source of the second switch tube is connected to the resistor.

5. The micro cathode arc thrust system according to claim 1, characterized in that: The liquid metal is gallium-based liquid metal.

6. The micro cathode arc thrust system according to claim 1, characterized in that: The heating unit is an electric heating plate.

7. The micro cathode arc thrust system according to claim 2, characterized in that: The temperature difference sensing device is a thermocouple.

8. The micro cathode arc thrust system according to claim 3 or claim 4, characterized in that: The first switch tube and the second switch tube are both IGBTs.

9. The micro cathode arc thrust system according to claim 7, characterized in that: The thermocouple is a K-type nickel-chromium-nickel-silicon thermocouple.

10. The micro cathode arc thrust system according to claim 7, characterized in that: The thermocouple is a T-type copper-copper-nickel thermocouple.

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