Combined experiment platform for testing effect of expelling space debris by laser

Abstract

The invention discloses a combined experiment platform for testing the effect of expelling space debris by laser, and provides a combined experiment platform which is high in precision and sensitivity and is used for testing the effect of expelling space debris by laser. The platform is formed by combining a plurality of systems such as a laser, a power supply and control system of the laser, a vacuum tank, a suspension structure, a high-precision camera and infrared camera combined camera shooting system and the like. Wherein the vacuum tank and the suspension structure are used for suspending a to-be-tested sample and providing an environment with a relatively high vacuum degree by virtue of vacuumizing of the molecular pump. The laser and the power supply and control system thereof are used for providing pulse laser with specific power and line width. And the high-precision camera and infrared camera combined camera system is used for observing and recording experimental phenomena, and solving the torsion angle of the sample and the position of laser action through an image processing algorithm. The method is more sensitive in response to micro force, interference of the damping effect and the heat effect of the atmosphere is well avoided, and high precision can be achieved.

Description

Technical Field

[0001] The present invention provides a combined experimental platform for testing the effect of laser deorbiting space debris. It relates to a combined experimental platform that simulates the space vacuum environment, facilitates long-term observation, and allows an external light source to act on internal samples, belonging to the field of testing equipment / experimental platforms. Background Art

[0002] With the rapid increase in the number of near-Earth orbit space debris (currently exceeding 130 million pieces), the risk of debris collision has increased geometrically, seriously threatening the safety of spacecraft. How to achieve satellite deorbiting and debris removal has become a hot issue in the aerospace field. From the late 1980s to the early 1990s, the United States proposed using ground-based or space-based lasers (wavelength 1.06 μm, pulse power about 100 kW) to irradiate debris, and the plasma recoil momentum generated by laser ablation was used to push the debris to a lower orbit, causing it to re-enter the atmosphere and burn. In 1996, Phipps systematically elaborated on this technical route in the paper "ORION: Clearing Near-Earth Space Debris Using a 20-kW, 500-Hz Repetitively Pulsed Laser". In 1997, the U.S. Air Force successfully observed fine-tuning of the debris orbit (Starfire Optical Range in New Mexico) using a ground laser in the "Laser Debris Removal" experiment. With the continuous progress of research, space-based laser debris removal technology has also been proposed. In 2017, Changchun Institute of Optics and Fine Mechanics proposed deploying a high-energy laser on a low Earth orbit (LEO) satellite platform. By precisely tracking and irradiating debris, a plasma recoil thrust is generated to decelerate it and make it fall into the atmosphere. The laser type is a pulsed fiber laser (wavelength 1.06 μm, average power 10 - 100 kW, pulse frequency 1 - 10 kHz). Combining the laser ablation thrust with the ion thruster of the satellite platform itself, orbit maintenance and attitude adjustment are achieved.

[0003] In existing research, most of the ground tests rely on macroscopic thrust sensors or high-speed camera displacement tracking. Not only is the sensitivity relatively low (only reaching the millinewton level), but there is still a certain difference from the real scenario of laser debris removal in the space vacuum environment. During the process of laser irradiation and ablation to form a plasma jet, the speed of the jet is greatly affected by the local air pressure, and the heat generated during the ablation process will also cause thermal expansion of the air flow. These will all affect the accuracy of the experimental results to a certain extent.

[0004] As a fundamental tool for micro-force measurement, the torsion balance has undergone three key stages of technological breakthroughs in its development process: First, in 1785, Cavendish pioneered the use of a wire torsion balance to measure the universal gravitation, laying the basic principle for micro-torque measurement. However, limited by the technological conditions at that time, its sensitivity could only reach the order of 10^-7 N·m, and environmental vibration and air damping seriously affected the measurement accuracy. With the progress of vacuum technology at the end of the 19th century, et al. placed the torsion balance in a vacuum environment of 10^-1 Pa level, and improved the sensitivity by two orders of magnitude to reach the order of 10^-9 N·m by eliminating the influence of forces such as air damping. At the same time, the use of a symmetric structure design effectively suppressed the interference of environmental vibration.

[0005] In summary, in order to solve the problems of accuracy and sensitivity in ground tests in the research of laser debris removal in space, the present invention proposes a combined experimental platform for testing the laser-driven space debris removal. Summary of the Invention

[0006] (1) Object of the Invention: The object of the present invention is to provide a combined experimental platform with high accuracy and sensitivity for testing the effect of laser-driven space debris removal. The platform is composed of a laser and its power supply and control system, a vacuum chamber and a suspension structure, a combined imaging system of a high-precision camera and an infrared camera, and other systems. Among them, the vacuum chamber and the suspension structure are used to suspend and place the sample to be tested and provide a high-vacuum environment by means of a molecular pump to pump out the vacuum. The laser and its power supply and control system are used to provide pulsed laser with specific power and linewidth. The combined imaging system of a high-precision camera and an infrared camera is used to observe and record the experimental phenomena, and calculate the torsion angle of the sample and the position of the laser action through an image processing algorithm.

[0007] (2) Technical Solution

[0008] The present invention is a combined experimental platform for testing the effect of laser-driven space debris removal. It is composed of a laser and its power supply and control system, a vacuum chamber and a suspension structure, a combined imaging system of a high-precision camera and an infrared camera, and other systems. Among them, the vacuum chamber and the suspension structure are the main body of the platform, and provide a group of windows with equal height and perpendicular to each other for installing the laser and its power supply and control system and the combined imaging system of a high-precision camera and an infrared camera.

[0009] The described laser, its power supply and control system are composed of a display screen, an integrated circuit board, a power supply, a capacitor, a laser main body, and a water cooling circulation part; the relationships among them are as follows: The capacitor is connected to the power supply to store charges to generate an instantaneous large current; the power supply is connected to the integrated circuit board and the laser main body to supply power to them; the laser main body is placed in a rectangular box to generate and emit high-pulse laser; the display screen is connected to the integrated circuit board to control the power supply of the laser by the power supply; the water cooling circulation is connected to the laser main body to cool the laser.

[0010] The described vacuum tank and suspension structure are composed of a vacuum tank and a suspension wire. The vacuum tank is cylindrical as a whole, with a certain curvature at the upper end cover and the tank bottom. The overall height is 495 mm and the diameter is 406 mm. Multiple hook points are built in at the top, and there are two observation windows, one large and one medium, on the side wall. An innovative design of using both horizontally and vertically is adopted, and the two observation windows are arranged at 90°, which is convenient for continuous observation while conducting experiments. A laser protection baffle is placed on the light-facing side of the side wall to prevent the laser from damaging the tank body. Multiple types of interfaces are opened on the tank body for vacuum pumping. Considering the high temperature resistance and strong ductility of gold, the suspension wire is made of gold wire with a diameter of 0.015 μm. One end is hung on the top of the tank body, and the other end is used to hang the sample.

[0011] The described high-precision camera and infrared camera are placed on one side facing the large observation window. The high-precision camera is used to obtain the position of the corner points through feature point detection, and then deduce the movement direction and speed of the feature points through the optical flow method, and then restore them to the movement characteristics of the sample. The infrared camera extracts the information of the four corner points of the sample and the ablation points of the laser through the method of feature point extraction, and obtains the position of the ablation points on the sample through perspective transformation.

[0012] (III) Advantages

[0013] ① High sensitivity. In a vacuum environment, a torsion balance is used for measurement. The torsion balance will not be affected by air resistance and is more sensitive to tiny forces. Therefore, the accuracy of this experimental system is higher than that of a micro-force meter.

[0014] ② High precision. Using this experimental system, the damping effect of the atmosphere and the interference of thermal effects are avoided, and its accuracy is higher than that of a micro-force meter.

[0015] ③ Intuitive. It can directly observe the movement characteristics of the fragments when rotating along the main axis after being irradiated by the laser, without the need to build a model and solve through experimental data.

[0016] ④ Strong expandability. Since this set of systems can simulate the vacuum environment in space and conduct micro-force measurement, more expandable experiments can be carried out on the basis of this set of systems. For example, by applying prestress to the suspended gold wire, the sample has a certain initial angular velocity, and then on this basis, the effect of the laser on the despinning of the fragments can be explored. Description of the Drawings

[0017] Figure 1 This is the external view of the vacuum chamber of the present invention.

[0018] Figure 2 This is the working flow chart of the test system of the present invention. Detailed implementation manners

[0019] 1. Platform setup. Place the vacuum chamber at the center, adjust the laser platform and the camera system to appropriate heights, and align them with the two observation windows respectively.

[0020] 2. Laser adjustment. After correctly connecting and turning on the water cooling circulation, turn on the power supply, adjust the output frequency and power of the laser on the display screen, and then turn on the switch on the circuit board to ensure that the laser can work properly.

[0021] 3. Sample selection and placement. Select the sample for the experiment, connect it to one end of the gold wire, cut the gold wire to an appropriate length, and hang the other end on the hook on the top cover of the vacuum chamber. At the same time, adjust the optical paths of the laser and the camera system to ensure that the laser can ablate the expected point and its effect can be captured by the camera system.

[0022] 4. Sealing and vacuum pumping. Close the top cover, evenly install four sets of fastening bolts along the circumference of the top cover and the tank body. Connect one interface on the tank body to the molecular pump, install a barometer on one interface, install a gas release valve on one interface, and seal the remaining interfaces to ensure the airtightness of the entire vacuum chamber. Then use the molecular pump to pump vacuum until a high vacuum environment is formed inside the tank.

[0023] 5. Conduct the experiment and record. Use the laser to align with a specific point on the sample, turn on the laser, and make it emit a beam with a specified energy and line width to ablate the sample. At the same time, use the camera system to record the movement of the sample and the ablation point.

[0024] 6. Experimental data processing. The high-precision camera is used to obtain the positions of the corner points through feature point detection, and then the movement directions and speeds of each feature point in the time series are deduced by the optical flow method, and then restored to the movement characteristics of the sample. The infrared camera extracts the information of the four corner points of the sample and the ablation point of the laser through the method of feature point extraction, and obtains the position of the ablation point on the sample through perspective transformation.

[0025] The rotation of the torsion balance is balanced by the restoring torque of the gold wire, the damping torque, and the laser driving torque:

[0026]

[0027] where

[0028] θ(t) is the torsional angular displacement;

[0029] is the torsional stiffness of the gold wire (G is the shear modulus, r is the radius, and L is the length);

[0030] is the internal friction damping coefficient (η is the material loss factor, and for gold it is on the order of 10 -4 magnitude).

[0031] Combined with the energy and line width of the laser, the quality and shape parameters of the sample, the motion characteristics of the sample, and the position of the ablation point on the sample, further quantitative analysis is carried out.

Claims

1. A combined experimental platform for testing the effect of laser in driving away space debris, characterized in that: It is composed of multiple systems such as a laser and its power supply and control system, a vacuum chamber and a suspension structure, and a combined imaging system of a high-precision camera and an infrared camera. Among them, the vacuum chamber and the suspension structure are the main body of the platform and provide a set of equidistant and mutually perpendicular viewing windows for installing the laser and its power supply and control system and the combined imaging system of the high-precision camera and the infrared camera. The laser and its power supply and control system consists of a display screen, an integrated circuit board, a power supply, a capacitor, a laser body, and a water cooling circulation part. The relationship between them is as follows: The capacitor is connected to the power supply to store charge to generate an instantaneous large current. The power supply is connected to the integrated circuit board and the laser body to supply power to them. The laser body is placed in a cuboid box to generate and emit high-pulse laser. The display screen is connected to the integrated circuit board to control the power supply of the laser by the power supply. The water cooling circulation is connected to the laser body to cool the laser. The vacuum chamber and the suspension structure are composed of a vacuum chamber and a suspension wire. The vacuum chamber is cylindrical as a whole, with a certain curvature at the upper end cover and the bottom of the tank. The overall height is 495 mm and the diameter is 406 mm. Multiple hanging hook points are built-in at the top, and there are two observation windows, one large and one medium, on the side wall. An innovative design of horizontal and vertical dual use is adopted, and the two observation windows are arranged at 90°. It is convenient to continuously observe while conducting experiments. A laser protection baffle is installed on the light-facing side of the side wall to prevent the laser from damaging the tank body. Various types of interfaces are opened on the tank body for vacuum pumping. Considering the high-temperature resistance and strong ductility of gold, the suspension wire is made of gold wire with a diameter of 0.015 μm. One end is hung at the top of the tank body, and the other end is used to hang the sample. The high-precision camera and the infrared camera are installed on one side facing the large observation window. The high-precision camera is used to obtain the position of the corner points by feature point detection, and then deduce the movement direction and speed of the feature points through the optical flow method, and then restore them to the movement characteristics of the sample. The infrared camera extracts the information of the four corner points of the sample and the ablation points of the laser through the method of feature point extraction, and obtains the position of the ablation points on the sample through perspective transformation.

2. The vacuum tank according to claim 1, wherein: The vacuum chamber as a whole is made of stainless steel with a wall thickness of 3 mm.

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