Electric thruster cathode autonomous activation method for high-flux atomic oxygen environment

Abstract

The invention belongs to the technical field of spacecraft electric propulsion systems, and discloses an electric thruster cathode autonomous activation method for a high-flux atomic oxygen environment. The method comprises the steps that S1, a cathode of an electric thruster is heated through current lower than the rated current of the cathode, an oxide layer of a cathode emitter is removed, and the activation frequency is recorded; s2, the cathode of the electric thruster is heated through cathode rated current, after the heating time is t3, an ignition power source and a touch holding power source of the electric thruster are turned on, if the contact holding current of the cathode of the electric thruster is larger than a cathode ignition threshold value I0 within a preset time period T0, the cathode heating power source and the ignition power source of the electric thruster are turned off, after the ignition time is kept t4, the touch holding power source is turned off, and the electric thruster is started; stopping ignition; otherwise, entering the step S3; s3, judging activation times gt; if the allowable activation frequency is N0, turning off the cathode heating power supply, the ignition power supply and the touch holding power supply; and if N is less than or equal to the allowed activation frequency N0, waiting for a second cooling duration t5, and skipping to the step S1.

Description

Technical Field

[0001] The present invention belongs to the technical field of spacecraft electric propulsion systems, and in particular relates to a method for autonomously activating the cathode of an electric thruster in a high-flux atomic oxygen environment, which is suitable for activating the cathode of an electric propulsion system of an ultra-low-orbit satellite. Background Art

[0002] Ultra-low-orbit satellites fly in low orbits, significantly improving the imaging resolution of optical payloads and reducing the latency of communication payloads. They offer significant advantages in high-resolution Earth observation and low-latency, high-speed satellite-to-ground communications. However, the low orbits of ultra-low-orbit satellites result in high atomic oxygen fluxes, several orders of magnitude higher than those of typical low-orbit satellites. The cathode emitter materials used in electric propulsion are typically lanthanum hexaboride or barium tungsten, which are very sensitive to atomic oxygen. Oxidation of the cathode emitter surface significantly reduces the cathode's electron emission capability, ultimately preventing the electric propulsion system from properly igniting in orbit.

[0003] In the existing electric propulsion system, when cathode ignition fails in orbit, the electric propulsion system directly switches to the backup thruster and uses the backup thruster to perform orbit control tasks.

[0004] Ultra-low-orbit satellites operate in a high-flux atomic oxygen environment. The main and backup electric thrusters will inevitably be affected by atomic oxygen throughout their life cycle, resulting in ignition failure. Therefore, autonomous cathode activation is required in orbit to avoid the main and backup thrusters from failing to work, affecting the satellite's normal orbit maintenance mission. Summary of the Invention

[0005] The technical problem solved by the present invention is: to overcome the shortcomings of the existing technology. To address this problem, the present invention proposes an autonomous cathode activation method for electric thrusters applied in ultra-low orbit high-flux atomic oxygen environments, ensuring that the electric thrusters can operate reliably for a long life in ultra-low orbit high-flux atomic oxygen environments.

[0006] The present invention solves the technical problem by providing a method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment. The electric thruster utilizes a continuously adjustable current heating power supply to heat the cathode. After cathode ignition failure occurs in the electric thruster, the method performs the following steps:

[0007] S1. Start the onboard autonomous cathode activation process: use a current lower than the cathode rated heating current to heat the cathode of the electric thruster, remove the oxide layer of the cathode emitter, and record the number of activations;

[0008] S2. Start the onboard autonomous ignition verification process: Heat the electric thruster cathode using the rated cathode heating current. After the heating time t3, turn on the electric thruster ignition power supply and the holding power supply. If the electric thruster cathode holding current exceeds the cathode ignition threshold I0 within the preset time period T0, turn off the electric thruster cathode heating power supply and ignition power supply. After maintaining the cathode ignition time t4, turn off the holding power supply, stop ignition, and end. Otherwise, proceed to step S3.

[0009] S3. If the number of activations is greater than the allowed number of activations N0, the autonomous activation is considered to have failed, and the cathode heating power supply, ignition power supply, and touch-holding power supply are turned off, and the process ends; if N ≤ the allowed number of activations N0, wait for the second cooling time t5 and jump to step S1.

[0010] Preferably, the onboard autonomous cathode activation process is as follows:

[0011] S1.1. Turn on the electric thruster cathode heating power supply, set the heating current to activation gear I1, heat the electric thruster cathode, wait for activation time t1, and then proceed to step S1.2;

[0012] S1.2. Turn off the electric thruster cathode heating power supply and wait for a first cooling time t2 until the electric thruster cathode cools down.

[0013] Preferably, the step S1.1 activates the gear I1 to set the cathode heating current value in the range of (0.4 to 0.8)*the rated heating current of the electric thruster cathode.

[0014] Preferably, the activation time t1 has a value range of [30 min, 120 min].

[0015] Preferably, the value range of the first cooling time t2 is [30 min, 60 min].

[0016] Preferably, the preset time period T0 is greater than the longest time required for the cathode of the electric thruster to be normally ignited.

[0017] Preferably, the cathode ignition threshold value I0 is a rated value of the cathode holding current after the cathode is normally ignited.

[0018] Preferably, the heating time t3 is in the range of [120s, 180s].

[0019] Preferably, the cathode ignition time t4 is in the range of [15 min, 30 min].

[0020] Preferably, the second cooling time t5 is in the range of [20 min, 30 min].

[0021] The beneficial effects of the present invention compared with the prior art are:

[0022] (1) The present invention can autonomously start the cathode activation process on board the satellite, remove the oxide layer of the cathode emitter, and verify whether the activation is successful through autonomous ignition after activation. Then, by repeating the activation process multiple times, the cathode is finally autonomously activated successfully, thereby preventing the electric thruster from being affected by atomic oxygen and unable to ignite normally on orbit.

[0023] (2) The present invention adopts a cathode heating power supply with continuously adjustable current, which realizes the flexible setting of the cathode activation current and can adapt to the autonomous activation of the cathode under different oxidation degrees, thus avoiding the inability to effectively remove the cathode surface oxide layer due to inappropriate cathode heating current.

[0024] (3) The present invention sets the cathode activation current to be lower than the rated cathode heating current, thereby avoiding cathode damage caused by excessive cathode heating current during the activation process while ensuring effective removal of the oxide layer. The method is safe and reliable.

[0025] (4) The present invention limits the number of activations in the cathode autonomous activation process to avoid repeated activation when cathode oxidation is particularly severe, which would cause the satellite to be unable to use the electric thruster to perform its mission normally for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of a method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the embodiments.

[0028] like Figure 1 As shown, the present invention proposes a method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment. The electric thruster uses a continuously adjustable current heating power supply to heat the cathode. The method is to perform the following steps after the electric thruster cathode ignition fails:

[0029] S1. Start the onboard autonomous cathode activation process: use a current lower than the cathode rated current to heat the cathode of the electric thruster, remove the oxide layer of the cathode emitter, and record the number of activations;

[0030] The onboard autonomous cathode activation process is as follows:

[0031] S1.1. Turn on the electric thruster cathode heating power supply, set the heating current to activation gear I1, heat the electric thruster cathode, wait for activation time t1, and then proceed to step S1.2;

[0032] Activate gear I1 to set the cathode heating current value in the range of (0.4~0.8)*electric thruster cathode rated heating current.

[0033] In a specific embodiment of the present invention, the rated heating current of the electric thruster cathode is 7.5A to 7.8A, the activation gear sets the cathode heating current value to 4A, and the activation time t1 has a value range of [30min, 120min].

[0034] S1.2. Turn off the electric thruster cathode heating power supply and wait for the first cooling time t2 until the electric thruster cathode cools down.

[0035] In a specific embodiment of the present invention, the value range of the first cooling time t2 is [30 min, 60 min].

[0036] S2. Start the onboard autonomous ignition verification process: Heat the electric thruster cathode using the rated cathode heating current. After the heating time t3, turn on the electric thruster ignition power supply and the holding power supply. If the electric thruster cathode holding current exceeds the cathode ignition threshold I0 within the preset time period T0, turn off the electric thruster cathode heating power supply and ignition power supply. After maintaining the ignition for t4, turn off the holding power supply, stop ignition, and end. Otherwise, proceed to step S3.

[0037] The preset time period T0 is greater than the longest time required for the cathode of the electric thruster to be normally ignited. In a specific embodiment of the present invention, the value is 120s.

[0038] The cathode ignition threshold I0 is the rated value of the cathode holding current after the cathode is normally ignited. In a specific embodiment of the present invention, the value is 0.5 A. The heating time t3 ranges from 120s to 180s. The ignition time t4 ranges from 15min to 30min.

[0039] S3. If the number of activations is greater than the allowed number of activations N0, the autonomous activation is considered to have failed, and the cathode heating power supply, ignition power supply, and touch-holding power supply are turned off to stop the cathode autonomous activation program; if N ≤ the allowed number of activations N0, wait for the second cooling time t5 and jump to step S1.

[0040] In a specific embodiment of the present invention, the second cooling time t5 is in the range of [20 min, 30 min].

[0041] If the electric thrusters on the satellite are equipped with main and backup cathodes, after the main cathode determines that the cathode autonomous activation has failed, it will switch to the backup cathode to continue the ignition mission.

[0042] If the electric thruster on the satellite is only equipped with a single cathode, but the electric thruster is equipped with a main and a backup, after the main electric thruster determines that the cathode has failed to be activated autonomously, it will switch to the backup electric thruster to continue the ignition mission.

[0043] The above parameters I1, I2, I0, t1, t2, t3, t4, t5, and T0 can all be modified through software annotation.

[0044] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solutions of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall fall within the scope of protection of the technical solutions of the present invention.

Claims

1. A method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment, wherein the electric thruster uses a continuously adjustable current heating power supply to heat the cathode, characterized in that After the electric thruster cathode ignition fails, perform the following steps: S1. Start the onboard autonomous cathode activation process: use a current lower than the cathode rated heating current to heat the cathode of the electric thruster, remove the oxide layer of the cathode emitter, and record the number of activations; S2. Start the onboard autonomous ignition verification process: Heat the electric thruster cathode using the rated cathode heating current. After the heating time t3, turn on the electric thruster ignition power supply and the holding power supply. If the electric thruster cathode holding current exceeds the cathode ignition threshold I0 within the preset time period T0, turn off the electric thruster cathode heating power supply and ignition power supply. After maintaining the cathode ignition time t4, turn off the holding power supply, stop ignition, and end. Otherwise, proceed to step S3. S3. If the number of activations is greater than the allowed number of activations N0, the autonomous activation is considered to have failed, and the cathode heating power supply, ignition power supply, and touch-holding power supply are turned off, and the process ends; if N ≤ the allowed number of activations N0, wait for the second cooling time t5 and jump to step S1.

2. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 1, characterized in that: The onboard autonomous cathode activation process is as follows: S1.

1. Turn on the electric thruster cathode heating power supply, set the heating current to activation gear I1, heat the electric thruster cathode, wait for activation time t1, and then proceed to step S1.2; S1.

2. Turn off the electric thruster cathode heating power supply and wait for a first cooling time t2 until the electric thruster cathode cools down.

3. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 2, characterized in that: The step S1.1 activates the gear I1 to set the cathode heating current value to a value range of: 0.4 to 0.8*the rated heating current of the electric thruster cathode.

4. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 2, characterized in that: The activation time t1 has a value range of [30 min, 120 min].

5. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 2, characterized in that: The value range of the first cooling time t2 is [30 min, 60 min].

6. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 1, characterized in that: The preset time period T0 is greater than the maximum time required for the cathode of the electric thruster to be normally ignited.

7. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 1, characterized in that: The cathode ignition threshold value I0 is the cathode holding current rated value after the cathode is normally ignited.

8. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 1, characterized in that: The heating time t3 range is [120s, 180s].

9. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 1, characterized in that: The cathode ignition time t4 range is [15min, 30min].

10. The method for autonomous cathode activation of an electric thruster in a high-flux atomic oxygen environment according to claim 1, characterized in that: The second cooling time t5 ranges from [20 min, 30 min].

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