A low temperature start-up method for high beam density variable thrust ion thrusters

Abstract

The application relates to the field of spacecraft propulsion technology, in particular to a low-temperature starting method suitable for a high-beam-density variable-thrust ion thruster, which comprises temperature state confirmation, step-by-step ignition of a neutralizer and a discharge chamber, grid power-on beam current, step-by-step anode current ladder loading, step-by-step working magnetic field ladder loading and beam closed-loop adjustment. Through the control strategy of adjusting the anode current first and then adjusting the excitation current, the ion beam current loading rate is effectively controlled; a step-by-step abnormal handling strategy is set for beam flickering, and when a serious fault occurs, the starting is restarted, and when a slight fault occurs, only the beam current is restarted and the magnetic field loading process is continued. The application solves the problem of frequent ion beam flickering during high-beam-density starting in a low-temperature environment, improves the starting reliability and safety, and can meet the on-orbit application requirements of ion electric propulsion systems of near-earth orbit satellites and deep space probes.

Description

Technical Field

[0001] This application relates to the field of spacecraft propulsion technology, and more specifically, to a cryogenic start-up method suitable for high beam density variable thrust ion thrusters. Background Technology

[0002] Variable thrust ion thrusters, with their outstanding advantage of wide-range and precisely adjustable thrust, have become the best choice for spacecraft to carry out drag-free flight missions and precise orbit maintenance missions. With the development of space engineering missions, the application scenarios and operating modes of variable thrust ion thrusters are constantly expanding. This places high demands on their adaptability to the space environment.

[0003] During ground-based development tests simulating typical space environments, it was found that when the variable-thrust ion thruster starts up at high beam density in a low-temperature environment, compared to normal temperature conditions, the slow heat transfer response of the entire structure makes it unable to quickly match the thermal equilibrium state required for stable operation of the ion thruster. This results in frequent unexpected ion beam flickering during startup. Severe beam flickering can cause hardware damage to the ion thruster and related components of its power supply unit, thereby affecting the on-orbit service life and reliability of electric propulsion products.

[0004] Therefore, researching cryogenic start-up methods for variable thrust ion thrusters suitable for high beam density is one of the key technologies that must be overcome to achieve on-orbit engineering applications and improve the lifespan and reliability of variable thrust ion thrusters, in response to the application requirements of different application scenarios and working modes. It is also an effective means to expand the application fields and improve the application strategies of variable thrust ion thrusters. Summary of the Invention

[0005] This application provides a low-temperature start-up method for high-current-density variable-thrust ion thrusters, which solves the problem of frequent ion beam flicker and low start-up reliability when variable-thrust ion thrusters are started up at high current density in low-temperature environments.

[0006] To achieve the above objectives, this application provides a cryogenic start-up method suitable for high beam density variable thrust ion thrusters, comprising the following steps: Step 1: Temperature status confirmation. Determine whether the temperature status of the temperature control point of the variable thrust ion thruster meets the thruster start-up requirements. If it does, proceed directly to Step 2. If it does not, first turn on the thermal control heating function and wait for the temperature to reach the standard before proceeding to Step 2. Step 2: Neutralizer and discharge chamber ignition. Simultaneously turn on the neutralizer heating power supply and the main cathode heating power supply. After the neutralizer has been heated for the preset time, start the neutralizer holding power supply and the neutralizer ignition power supply to ignite the neutralizer. After the neutralizer is successfully ignited and the main cathode has been heated for the preset time, start the main cathode holding power supply, the main cathode ignition power supply, the anode power supply and the excitation power supply to ignite the discharge chamber. Step 3: Powering on the gate assembly to extract the ion beam. After successful ignition in the discharge chamber, a voltage is applied to the gate assembly to extract the ion beam. Step 4: The anode current in the discharge chamber is applied in steps. After the beam is successfully extracted from the grid assembly, the anode current is gradually increased in a manner that does not exceed the set step size. After each adjustment, the stable time is maintained for no less than the set value until the anode current reaches the target thrust operating point value. Step 5: Step-by-step loading of the working magnetic field in the discharge chamber and closed-loop adjustment of the beam current. After the anode current is loaded, the excitation current is gradually increased in a manner that does not exceed the set step size. After each adjustment, the beam current is kept stable for no less than the set time until the excitation current reaches the target thrust working point value. Then, the closed-loop adjustment of the beam current is started to stabilize the ion beam within the target control range.

[0007] Furthermore, in step 2, the neutralizer ignition process is as follows: the neutralizer heating power supply and the main cathode heating power supply are started simultaneously; after the neutralizer heating power supply is turned on for 120 seconds, the neutralizer holding power supply and the neutralizer ignition power supply are turned on, and the timer starts and is maintained for a maximum of 180 seconds; if the neutralizer holding current is greater than or equal to 80% of the set value within these 180 seconds and is maintained for more than 5 seconds, the neutralizer ignition is determined to be successful, and the neutralizer heating power supply and the neutralizer ignition power supply are turned off; otherwise, all the turned-on power supplies are turned off, and the neutralizer ignition process is repeated after natural cooling for at least 5 seconds.

[0008] Furthermore, in step 2, the discharge chamber ignition process is as follows: After the neutralizer is successfully ignited and the main cathode heating power supply has been turned on for at least 180 seconds, the main cathode contact power supply, main cathode ignition power supply, anode power supply, and excitation power supply are turned on, and timing begins and is maintained for a maximum of 120 seconds; if the anode current is greater than or equal to 80% of the set value within these 120 seconds and is maintained for more than 5 seconds, the discharge chamber is determined to be successfully ignited, and the main cathode heating power supply and main cathode ignition power supply are turned off; otherwise, all the turned-on power supplies are turned off, and the process is repeated after natural cooling for at least 5 seconds.

[0009] Furthermore, during the ignition process in the discharge chamber, the anode current is set to half of the anode current value at the target thrust operating point, and the excitation current is set to half of the excitation current value at the target thrust operating point.

[0010] Furthermore, in step 4, the anode current adjustment step size shall not exceed 0.2A, and the stabilization time after each adjustment shall not be less than 5s.

[0011] Furthermore, in step 5, the excitation current adjustment step size shall not exceed 0.05A, and the induced current shall be stable for no less than 10s after each adjustment.

[0012] Furthermore, during steps 3 to 5, an abnormal handling process is also included. The abnormal handling process includes a first abnormal handling strategy and a second abnormal handling strategy. Specifically, when beam flicker simultaneously causes the anode current or neutralizer holding current to return to zero, it is determined to be a serious fault situation, and the first abnormal handling strategy is executed. When beam flicker only manifests as a momentary drop in the gate ion beam current but the anode current and neutralizer holding current remain normal, it is determined to be a minor fault situation, and the second abnormal handling strategy is executed.

[0013] Furthermore, the first abnormal handling strategy is to shut down all powered on power supplies, maintain normal gas supply for cooling for at least 15 seconds, and then restart ignition according to steps 1 to 5. The second abnormal handling strategy is to maintain the current working state for at least 10 seconds, restart the gate assembly for beam priming, and maintain the beam priming operation under the current parameters for at least 15 seconds. After that, continue to adjust the excitation current according to the working magnetic field loading process when the beam priming is interrupted, until the ion beam reaches the beam control range of the target thrust working point.

[0014] Furthermore, in steps 2 to 5, a control strategy is adopted to first adjust the anode current and then adjust the excitation current. The anode current is controlled in an open loop during the ignition stage and the anode current loading stage, and the excitation current is controlled in a closed loop after the working magnetic field loading is completed and the beam current is stable.

[0015] This application provides a cryogenic start-up method suitable for high beam density variable thrust ion thrusters, which has the following advantages: This application utilizes the technical feature of variable-thrust ion thrusters where both the discharge current and working magnetic field can be adjusted over a wide range. Combining the rapid adjustment characteristics of the electric field on plasma density and the gradual adjustment characteristics of the magnetic field on plasma confinement, a matching adjustment strategy of first adjusting the anode current and then adjusting the working magnetic field is adopted. This effectively controls the loading rate of the ion beam while ensuring normal ignition of the discharge chamber and normal beam priming of the grid assembly. It avoids beam flicker caused by thermal equilibrium mismatch in low-temperature environments, improves the reliability and safety of variable-thrust ion thrusters at low temperatures and high beam density, and reduces the risk of hardware loss caused by ion beam flicker under high beam density. This can meet the application requirements of ion electric propulsion products for near-Earth orbit satellites and deep space probes in on-orbit flight missions. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of the application and to make other features, objects, and advantages of the application more apparent. The illustrative embodiments and descriptions of this application are used to explain the application and do not constitute an undue limitation of the application. In the drawings: Figure 1 This is a schematic diagram of the steps of a cryogenic start-up method for a high beam density variable thrust ion thruster provided in the embodiments of this application; Figure 2 This is a schematic diagram of the ignition process of the neutralizer and discharge chamber according to the embodiments of this application; Figure 3 This is a schematic diagram of the stepwise stepped loading of the anode current in the discharge chamber according to an embodiment of this application; Figure 4 This is a schematic diagram of the stepwise, stepped loading of the working magnetic field of the discharge chamber according to an embodiment of this application; Figure 5 This is a schematic diagram of the full-process power-on timing of a cryogenic start-up method for a high beam density variable thrust ion thruster provided in the embodiments of this application. Detailed Implementation

[0017] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0018] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0019] In this application, the terms "upper," "lower," "left," "right," "front," "rear," "top," "bottom," "inner," "outer," "middle," "vertical," "horizontal," "lateral," and "longitudinal" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0020] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0021] In addition, the term "multiple" should mean two or more.

[0022] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0023] like Figure 1 As shown, this application provides a cryogenic start-up method suitable for high-current-density variable-thrust ion thrusters. Utilizing the technical characteristic that both the discharge current and working magnetic field of variable-thrust ion thrusters can be adjusted over a wide range, and combining the differential influence of electric and magnetic fields on plasma discharge characteristics, the matching adjustment of the discharge current and working magnetic field not only effectively controls the ion beam loading time but also further improves the reliability and safety of cryogenic, high-current-density start-up of variable-thrust ion thrusters. Thus, while ensuring the on-orbit start-up time requirements of variable-thrust ion thrusters, it can effectively reduce the hardware loss risk caused by ion beam scintillation under high current density. Specifically, the method includes the following steps: Step 1: Temperature status confirmation. Determine whether the temperature status of the temperature control point of the variable thrust ion thruster meets the thruster start-up requirements. If it does, proceed directly to Step 2. If it does not, first turn on the thermal control heating function and wait for the temperature to reach the standard before proceeding to Step 2. Specifically, by determining whether the temperature of the variable-thrust ion thruster's temperature control point has reached the minimum ignition start-up temperature specified by the spacecraft, if it has, the process proceeds directly to the next step; if it is below the requirement, the thermal control heating function is activated first, and the thruster is started only after the temperature reaches the required level. This ensures that the thruster only enters the ignition process when it meets the minimum start-up temperature conditions, avoiding start-up failures caused by insufficient insulation performance or material shrinkage at low temperatures, and improving the success rate of low-temperature start-up.

[0024] Step 2: Ignition of the neutralizer and discharge chamber, such as Figure 2 As shown, the neutralizer heating power supply and the main cathode heating power supply are turned on simultaneously. After the neutralizer heating reaches the preset time, the neutralizer holding power supply and the neutralizer ignition power supply are started to ignite the neutralizer. After the neutralizer is successfully ignited and the main cathode heating reaches the preset time, the main cathode holding power supply, the main cathode ignition power supply, the anode power supply and the excitation power supply are started to ignite the discharge chamber. Furthermore, the neutralizer ignition process is as follows: the neutralizer heating power supply and the main cathode heating power supply are started simultaneously; 120 seconds after the neutralizer heating power supply is turned on, the neutralizer holding power supply and the neutralizer ignition power supply are turned on, the timer starts and is maintained for a maximum of 180 seconds; if the neutralizer holding current is greater than or equal to 80% of the set value within these 180 seconds and is maintained for more than 5 seconds, the neutralizer ignition is determined to be successful, and the neutralizer heating power supply and the neutralizer ignition power supply are turned off; otherwise, all the turned-on power supplies are turned off, and the neutralizer ignition process is repeated after natural cooling for at least 5 seconds to avoid heat accumulation damage caused by multiple consecutive ignitions.

[0025] Furthermore, the discharge chamber ignition process is as follows: After the neutralizer ignites successfully and the main cathode heating power supply has been on for at least 180 seconds, the main cathode contact power supply, main cathode ignition power supply, anode power supply, and excitation power supply are turned on, and timing begins and is maintained for a maximum of 120 seconds; if the anode current is greater than or equal to 80% of the set value within these 120 seconds and is maintained for more than 5 seconds, the discharge chamber ignition is considered successful, and the main cathode heating power supply and main cathode ignition power supply are turned off; otherwise, all on power supplies are turned off, and the process is allowed to cool naturally for at least 5 seconds before the neutralizer and discharge chamber ignition process is repeated to ensure that each ignition attempt starts from the initial state after a complete reset, avoiding unpredictability caused by residual states.

[0026] Furthermore, during the ignition process in the discharge chamber, the anode current is set to half of the anode current value at the target thrust operating point, and the excitation current is set to half of the excitation current value at the target thrust operating point.

[0027] Specifically, step 2 employs a staged ignition strategy, first igniting the neutralizer and then the discharge chamber. Precise control of heating time, ignition duration, and current threshold ensures reliable ignition of the neutralizer and discharge chamber under cryogenic conditions. Simultaneously, half-current and half-magnetic field ignition is used, equivalent to establishing the initial discharge at one-quarter of the rated operating point power density, effectively reducing the thermal shock to the discharge chamber walls and cathode during the initial discharge at low temperatures. Furthermore, the half-excitation current results in a lower magnetic field confinement strength, allowing the plasma greater freedom to interact with the walls, which is beneficial for the initial discharge establishment and avoids the problem of small electron cyclotron radii and difficulty in reaching the anode to form a discharge circuit under strong magnetic field conditions. After the discharge is established and stabilized, the target operating point value is gradually reached through subsequent step-by-step loading.

[0028] Step 3: Powering on the gate assembly to extract the ion beam. After successful ignition in the discharge chamber, a voltage is applied to the gate assembly to extract the ion beam. Specifically, by applying a high-voltage electric field (positive high voltage to the screen grid and negative high voltage to the acceleration grid) between the screen grid and the acceleration grid, ionized ions in the discharge chamber are extracted from the plasma and accelerated to form an ion beam. Successful beam extraction signifies that the plasma source has transitioned from "successful ignition" to "beam output" operation, providing a beam feedback reference for subsequent stepwise loading of the anode current and magnetic field. Simultaneously, it ensures that the normal operation capability of the extraction system is verified under low power conditions, avoiding blindly increasing the discharge power without confirming the beam extraction capability, which could lead to beam anomalies.

[0029] Step 4: Apply a step-by-step, stepped loading of the anode current in the discharge chamber, such as... Figure 3 As shown, after the beam is successfully extracted from the gate assembly, the anode current is gradually increased in a manner not exceeding the set step size. After each adjustment, the stable time is maintained for no less than the set value until the anode current reaches the target thrust operating point value. Furthermore, the anode current adjustment step should not exceed 0.2A, and the stabilization time after each adjustment should not be less than 5s.

[0030] Specifically, based on the thermal inertia time constant of the discharge chamber (typically 2-5 s), the anode current is gradually increased in steps not exceeding 0.2 A, ensuring that the power increase corresponding to each current increment is insufficient to trigger an unexpected jump in the discharge mode. After each adjustment, the current is stabilized for at least 5 seconds to ensure that the plasma density and wall temperature within the discharge chamber reach a new thermal equilibrium state before proceeding to the next adjustment, thus avoiding beam impact and discharge instability caused by thermal inertia hysteresis.

[0031] Step 5: Step-by-step loading of the working magnetic field in the discharge chamber and adjustment of the closed-loop beam current, such as... Figure 4 As shown, after the anode current is loaded, the excitation current is gradually increased in a manner not exceeding the set step size. After each adjustment, the beam current is kept stable for no less than the set time until the excitation current reaches the target thrust operating point value. Then, the beam current closed-loop adjustment is started to stabilize the ion beam within the target control range.

[0032] Furthermore, the excitation current adjustment step should not exceed 0.05A, and the induced current should be stable for at least 10 seconds after each adjustment.

[0033] Specifically, the time constant for the effect of magnetic field changes on plasma confinement and transport characteristics is typically 5–8 s. The excitation current is gradually increased in steps not exceeding 0.05 A to ensure that the plasma density and temperature changes corresponding to each magnetic field increment are within a controllable range. After each adjustment, stabilization is performed for at least 10 s to ensure that the ion beam reaches a stable state under the new magnetic field confinement conditions before proceeding to the next adjustment, thus avoiding beam flicker caused by excessively rapid magnetic field changes.

[0034] Furthermore, during steps 3 to 5, an abnormal handling process is also included. The abnormal handling process includes a first abnormal handling strategy and a second abnormal handling strategy. Specifically, when beam flicker simultaneously causes the anode current or neutralizer holding current to return to zero, it is determined to be a serious fault situation, and the first abnormal handling strategy is executed. When beam flicker only manifests as a momentary drop in the gate ion beam current but the anode current and neutralizer holding current remain normal, it is determined to be a minor fault situation, and the second abnormal handling strategy is executed.

[0035] Furthermore, the first abnormal handling strategy is to shut down all powered on power supplies, maintain normal gas supply for cooling for at least 15 seconds, and then restart ignition according to steps 1 to 5. The second abnormal handling strategy is to maintain the current working state for at least 10 seconds, restart the gate assembly for beam priming, and maintain the beam priming operation under the current parameters for at least 15 seconds. After that, continue to adjust the excitation current according to the working magnetic field loading process when the beam priming is interrupted, until the ion beam reaches the beam control range of the target thrust working point.

[0036] Specifically, the anode current and neutralizer holding current are direct indicators of the plasma maintenance in the discharge chamber and neutralizer. Both returning to zero signifies that the plasma source has become unstable and must be restarted. Conversely, if both remain normal except for a decrease in beam current, it indicates that the plasma source is still stable and can be restored simply by readjusting the extraction conditions. Therefore, when beam flashing simultaneously causes the anode current or neutralizer holding current to return to zero, it indicates that the main discharge circuit of the discharge chamber or neutralizer has been interrupted, representing a serious fault. The first abnormal handling strategy is to shut down all active power supplies, maintain normal gas supply for at least 15 seconds to cool, and then restart the system following steps 1 to 5. This ensures that the discharge chamber and cathode temperatures are sufficiently reduced, preventing the restart under high-temperature conditions from exacerbating structural thermal stress. When beam flicker is manifested only as a momentary drop in the gate ion beam current while the anode current and neutralizer holding current remain normal, it indicates that the plasma source is working normally but the extraction process is subject to momentary interference, which is a minor fault. The second abnormal handling strategy is executed, namely, re-energizing the gate assembly to induce the beam current and operating the beam current under the current parameter conditions for at least 15 seconds. After that, the excitation current is adjusted according to the working magnetic field loading process when the beam current is interrupted until the ion beam current reaches the beam control range of the target thrust operating point. This avoids excessive response during minor beam flicker and allows for rapid recovery without the need for re-ignition, significantly saving startup time.

[0037] Furthermore, in steps 2 to 5, a control strategy is adopted to first adjust the anode current and then adjust the excitation current. The anode current is controlled in an open loop during the ignition stage and the anode current loading stage, and the excitation current is controlled in a closed loop after the working magnetic field loading is completed and the beam current is stable.

[0038] Specifically, the cryogenic startup method for high beam density variable thrust ion thrusters provided in this application adopts a control strategy of first adjusting the anode current and then adjusting the excitation current, and uses differentiated control methods combining open-loop and closed-loop at different stages. This control strategy is closely integrated with the satellite application scenario and together constitutes a complete on-orbit startup control scheme. The specific implementation process is as follows: First, after the temperature at the temperature control point of the variable-thrust ion thruster meets the start-up requirements, it is necessary to confirm that the gas supply pressure of the anode, the hollow cathode of the neutralizer, and the hollow cathode of the main cathode inside the thruster is in a balanced state. Gas supply pressure balance is confirmed through real-time monitoring by pressure sensors in the on-orbit gas supply system, ensuring stable pressure and uniform gas flow in each gas supply pipeline during ignition, avoiding ignition failure or unstable discharge due to pressure fluctuations. This solves the problem of gas supply imbalance caused by gas condensation or pipeline pressure drop under low-temperature conditions, and is a crucial preliminary step in ensuring ignition reliability.

[0039] Secondly, after confirming gas supply balance, ignition and subsequent steps are executed. During the ignition and anode current loading phases, open-loop control is applied to the anode current, meaning the current command is directly applied according to a preset timing and step size, without relying on feedback signals for adjustment. At this stage, the plasma in the discharge chamber is not yet fully stable, and the ion beam signal exhibits significant noise and fluctuations. If closed-loop control is used, feedback noise may cause adjustment oscillations or even malfunctions, interfering with the establishment of the discharge. Open-loop control avoids these problems, gradually building up discharge power in a deterministic stepping manner, ensuring a smooth transition of the plasma to a stable state. Simultaneously, the timing arrangement of adjusting the anode current first and then the excitation current utilizes the rapid response characteristics of the electric field to plasma density, quickly establishing sufficient plasma density and discharge power under low magnetic field conditions, allowing the discharge chamber to enter a stable operating state.

[0040] Subsequently, after the working magnetic field is loaded in stages and the beam stabilizes, the system switches to closed-loop control of the excitation current. Using the ion beam extracted from the gate assembly as a feedback signal, the beam magnitude is monitored in real time and compared with the target value. The excitation current is automatically adjusted based on the deviation to ensure the beam remains stable within the target control range. The timing of switching from open-loop to closed-loop control after beam stabilization is chosen because the plasma state in the discharge chamber has reached thermal equilibrium, resulting in a smooth and reliable beam signal that provides accurate feedback input for closed-loop control, avoiding erroneous adjustments caused by signal instability in the initial stages of closed-loop control. This closed-loop control strategy addresses disturbances such as space environment temperature changes and power bus fluctuations encountered during satellite operation. By adjusting the excitation current in real time to compensate for beam deviations, it ensures that the thruster maintains a stable beam output throughout long-term operation.

[0041] like Figure 5 As shown, the power-on sequence for the entire process is as follows: At time T0, the neutralizer heating power supply and the main cathode heating power supply are started simultaneously; at time T0+120s, the neutralizer holding power supply and the ignition power supply are started to ignite the neutralizer; after the neutralizer is successfully ignited and the main cathode heating has been on for ≥180s, the main cathode holding power supply, the main cathode ignition power supply, the anode power supply (half current), and the excitation power supply (half magnetic field) are started to ignite the discharge chamber; after the discharge chamber is successfully ignited (the anode current is ≥80% of the set value and maintained for 5s), the grid assembly is powered on to draw the beam current; then, the anode current is gradually loaded to the target value in steps not exceeding 0.2A; finally, the excitation current is gradually loaded to the target value in steps not exceeding 0.05A and the beam current closed-loop adjustment is started.

[0042] More specifically, in actual satellite applications, the above control strategy is manifested as follows: after the ion thruster is successfully started, it enters a steady-state working mode. The anode current is maintained at the target thrust operating point value and continues to use open-loop control (its value is jointly determined by the gas supply flow rate and the grid voltage, and open-loop control is sufficient to ensure its long-term stability). The excitation current is switched to closed-loop control. The magnitude of the excitation current is adjusted in real time through the beam feedback signal to maintain the beam within the beam control range corresponding to the target thrust operating point. This accurately compensates for changes in magnetic field distribution caused by factors such as changes in discharge chamber wall temperature and accelerated grid thermal deformation, effectively suppressing beam drift and ensuring that the thruster maintains high-precision thrust output during on-orbit missions lasting thousands of hours.

[0043] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A cryogenic start-up method suitable for high beam density variable thrust ion thrusters, characterized in that, Includes the following steps: Step 1: Temperature status confirmation. Determine whether the temperature status of the temperature control point of the variable thrust ion thruster meets the thruster start-up requirements. If it does, proceed directly to Step 2. If it does not, first turn on the thermal control heating function and wait for the temperature to reach the standard before proceeding to Step 2. Step 2: Neutralizer and discharge chamber ignition. Simultaneously turn on the neutralizer heating power supply and the main cathode heating power supply. After the neutralizer has been heated for the preset time, start the neutralizer holding power supply and the neutralizer ignition power supply to ignite the neutralizer. After the neutralizer is successfully ignited and the main cathode has been heated for the preset time, start the main cathode holding power supply, the main cathode ignition power supply, the anode power supply and the excitation power supply to ignite the discharge chamber. During the ignition process in the discharge chamber, the anode current is set to half of the anode current value at the target thrust operating point, and the excitation current is set to half of the excitation current value at the target thrust operating point. Step 3: Powering on the gate assembly to extract the ion beam. After successful ignition in the discharge chamber, a voltage is applied to the gate assembly to extract the ion beam. Step 4: The anode current in the discharge chamber is applied in steps. After the beam is successfully extracted from the grid assembly, the anode current is gradually increased in a manner that does not exceed the set step size. The stabilization time after each adjustment is not less than the set value. The anode current adjustment step size does not exceed 0.2A, and the stabilization time after each adjustment is not less than 5s, until the anode current reaches the target thrust operating point value. Step 5: Step-by-step loading of the working magnetic field in the discharge chamber and closed-loop adjustment of the beam current. After the anode current is loaded, the excitation current is gradually increased in a manner that does not exceed the set step size. After each adjustment, the beam current is kept stable for no less than the set time. The excitation current adjustment step size does not exceed 0.05A. After each adjustment, the beam current is kept stable for no less than 10s until the excitation current reaches the target thrust operating point value. Then, the closed-loop adjustment of the beam current is started to stabilize the ion beam within the target control range. In steps 2 to 5, a control strategy is adopted to first adjust the anode current and then adjust the excitation current. The anode current is controlled in an open loop during the ignition and anode current loading stages, and the excitation current is controlled in a closed loop after the working magnetic field loading is completed and the beam current is stable.

2. The cryogenic start-up method for a high beam density variable thrust ion thruster according to claim 1, characterized in that, In step 2, the neutralizer ignition process is as follows: Simultaneously start the neutralizer heating power supply and the main cathode heating power supply; After the neutralizer heating power is turned on for 120 seconds, the neutralizer holding power and neutralizer ignition power are turned on to start the timer and maintain it for a maximum of 180 seconds. If the neutralizer holding current is greater than or equal to 80% of the set value within 180 seconds and is maintained for more than 5 seconds, the neutralizer is determined to be successfully ignited, and the neutralizer heating power and neutralizer ignition power are turned off. Otherwise, turn off all powered devices and allow them to cool naturally for at least 5 seconds before re-executing the neutralizer ignition process.

3. The cryogenic start-up method for a high beam density variable thrust ion thruster according to claim 2, characterized in that, In step 2, the ignition process of the discharge chamber is as follows: After the neutralizer is successfully ignited and the main cathode heating power supply has been turned on for at least 180 seconds, turn on the main cathode holding power supply, the main cathode ignition power supply, the anode power supply and the excitation power supply, start timing and maintain it for a maximum of 120 seconds. If the anode current is greater than or equal to 80% of the set value within 120 seconds and is maintained for more than 5 seconds, the discharge chamber is determined to be successfully ignited, and the main cathode heating power supply and the main cathode ignition power supply are turned off. Otherwise, turn off all powered devices and allow them to cool naturally for at least 5 seconds before re-executing the neutralizer and discharge chamber ignition process.

4. The cryogenic start-up method for a high beam density variable thrust ion thruster according to claim 1, characterized in that, During steps 3 to 5, an exception handling process is also included, which comprises a first exception handling strategy and a second exception handling strategy, wherein: When beam flicker simultaneously causes the anode current or neutralizer holding current to drop to zero, it is considered a serious fault and the first abnormal handling strategy is executed; when beam flicker only manifests as a momentary drop in the gate ion beam current but the anode current and neutralizer holding current remain normal, it is considered a minor fault and the second abnormal handling strategy is executed.

5. The cryogenic start-up method for a high beam density variable thrust ion thruster according to claim 4, characterized in that, The first abnormal handling strategy is to shut down all powered on power, maintain normal gas supply for cooling for at least 15 seconds, and then restart ignition according to steps 1 to 5. The second abnormal handling strategy is to maintain the current working state for at least 10 seconds, restart the gate assembly for beam priming, and maintain the beam priming operation under the current parameters for at least 15 seconds. After that, continue to adjust the excitation current according to the working magnetic field loading process when the beam priming is interrupted until the ion beam reaches the beam control range of the target thrust working point.

Images