Electromagnetic pattern test system for high-frequency induction plasma equipment

Abstract

The invention discloses an electromagnetic pattern test system for high-frequency induction plasma equipment. The electromagnetic pattern test system comprises the high-frequency induction plasma equipment, an electromagnetic wave shielding test cabin, a vector network analyzer, an upper computer and airflow treatment equipment. The system can be detached and moved, is convenient to adapt to the generation position of a new medium, and solves the problem that the high-frequency induction wind tunnel cannot be subjected to an electromagnetic pattern test due to the fact that the new medium cannot move into a darkroom. Besides, the system is provided with an arc guide rail, so that the receiving antenna can measure S21 parameters at different angles by taking the transmitting antenna as a circle center, the moving angles of the receiving antenna at each time can be the same, the distance between the receiving antenna and the transmitting antenna is kept unchanged, and finally, a transmitting antenna directional diagram is formed by summarizing the results of all the angles.

Description

Technical Field

[0001] The invention relates to the field of microwave testing, and in particular to an electromagnetic directional pattern testing system for high-frequency induction plasma equipment. Background Art

[0002] The directivity of an antenna refers to its ability to radiate electromagnetic waves in a certain direction in free space. For a receiving antenna, directivity means that the antenna has different receiving capabilities for electromagnetic waves coming from different directions. The directivity of an antenna is usually represented by a radiation pattern.

[0003] Most of the existing antenna pattern tests are carried out in a microwave darkroom, which can shield the magnetic interference from the outside and absorb the internal reflected waves to test the purity of the electromagnetic environment. First, the receiving antenna is fixed and then the transmitting antenna is rotated. The S21 parameters at different angles are tested using a vector network analyzer to calculate the antenna pattern.

[0004] When the antenna is not in free space (for example, after changing the medium), it is necessary to understand the antenna pattern in the new medium to deduce the electromagnetic characteristics of the new medium. The new medium is often difficult to move into the darkroom due to its properties, or the equipment that produces the new medium is too large, which causes inconvenience in pattern testing.

[0005] High-frequency induction wind tunnels will generate large radio frequency interference during the process of generating plasma, affecting the normal operation of surrounding mechanical equipment, observation equipment, measuring equipment, etc., resulting in the inability to carry out electromagnetic testing smoothly. Summary of the invention

[0006] In view of the above-mentioned deficiencies in the prior art, the electromagnetic radiation pattern test system for high-frequency induction plasma equipment provided by the present invention solves the problem that the new medium cannot be moved into the darkroom, resulting in the inability to perform electromagnetic radiation pattern testing in the high-frequency induction wind tunnel.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0008] Provided is an electromagnetic radiation pattern test system for high-frequency induction plasma equipment, which includes high-frequency induction plasma equipment, an electromagnetic wave shielding test chamber, a vector network analyzer, a host computer and an airflow processing device;

[0009] The high-frequency induction plasma device comprises a high-frequency plasma heater, a nozzle and a plasma chamber; the output end of the high-frequency plasma heater is connected to one end of the plasma chamber through the nozzle; the other end of the plasma chamber is connected to the airflow processing device; at least one side of the plasma chamber is provided with an observation window; a transmitting antenna is provided in the plasma chamber; the transmitting antenna is connected to the signal transmitting end of the vector network analyzer;

[0010] A wave-transmitting window is provided on the electromagnetic wave shielding test cabin, an arc-shaped guide rail is provided in the electromagnetic wave shielding test cabin, a receiving antenna is slidably provided on the arc-shaped guide rail, and the receiving antenna is connected to the signal receiving end of the vector network analyzer; the center of the arc-shaped guide rail is the position of the transmitting antenna;

[0011] The arc-shaped guide rail is used to adjust the signal receiving azimuth of the receiving antenna;

[0012] A receiving antenna, used for receiving the signal transmitted through the plasma by the transmitting antenna through the observation window and the wave-transmitting window, and sending the received signal to the vector network analyzer;

[0013] Vector network analyzer for testing S21 parameters based on the signal from the receiving antenna;

[0014] The host computer is used to calculate the electromagnetic radiation pattern of the high-frequency induction plasma device according to the S21 parameters obtained by the vector network analyzer test.

[0015] The beneficial effects of the present invention are as follows: the high-frequency induction plasma equipment, electromagnetic wave shielding test chamber, vector network analyzer, host computer and airflow processing equipment of the system can be disassembled and moved, so as to adapt to the generation position of the new medium, thereby solving the problem that the new medium cannot be moved into the darkroom, resulting in the high-frequency induction wind tunnel being unable to perform electromagnetic radiation pattern testing. In addition, by setting up an arc guide rail, the system enables the receiving antenna to measure the S21 parameters at different angles with the transmitting antenna as the center of the circle. The angle of each movement of the receiving antenna can be the same and the distance from the transmitting antenna can be kept constant. Finally, the radiation pattern of the transmitting antenna is formed by summarizing the results of each angle.

[0016] Furthermore, the electromagnetic wave shielding test cabin is a metal room, the outer wall of the metal room is wrapped with aluminum foil and grounded; the inner wall of the metal room is covered with conical absorbing material; doors for passage are provided on the left and right sides of the metal room; the electromagnetic wave shielding test cabin is in contact with the plasma cabin, and an inward-opening door is provided on the contacting side, and the wave-transmitting window is located on the inward-opening door.

[0017] The technical effect of adopting the above-mentioned further scheme is as follows: the outer surface of the electromagnetic wave shielding test cabin is completely covered with metal, and the outer metal shell is grounded, ensuring that electromagnetic transmission is completely impossible inside and outside the electromagnetic wave shielding test cabin; the inside of the electromagnetic wave shielding test cabin is covered with absorbing materials, ensuring that during the experiment, the electromagnetic waves in the cabin will not be repeatedly reflected on the inner wall of the shielding cabin, affecting the directional pattern test results, thereby ensuring the measurement accuracy of the electromagnetic directional pattern of this system in different scenarios.

[0018] Furthermore, the dimensions of the metal room are 2.24m×1.9m×2.2m; the thickness of the aluminum foil is 0.001m; the cone height of the conical absorbing material is 0.2m, and the operating frequency band is 2-40GHz; the dimensions of the inner door are 1m×1.3m; and the dimensions of the wave-transmitting window are 0.48m×0.48m.

[0019] The technical effect of adopting the above further solution is: the floor space of the electromagnetic wave shielding test chamber is effectively controlled, and most interference signals can be shielded, laying the foundation for the portability of the system.

[0020] Furthermore, the radius of the circular arc guide rail is 2 m, the chord length is 2 m, and the arc span is plus or minus 60 degrees.

[0021] The technical effect of adopting the above further solution is: the receiving antenna can receive signals within the range of plus or minus 60 degrees, thereby improving the measurement accuracy of the electromagnetic radiation pattern.

[0022] Furthermore, an optical platform for placing the arc-shaped guide rail is also provided in the electromagnetic wave shielding test chamber, and the optical platform is calibrated by a laser level so that the arc-shaped guide rail remains level.

[0023] The technical effect of adopting the above further solution is: the setting of the optical platform can ensure that the arc-shaped guide rail remains horizontal, thereby ensuring the horizontal movement of the receiving antenna and ensuring the measurement accuracy of the electromagnetic radiation pattern.

[0024] Furthermore, a pneumatic feeding mechanism is provided in the plasma chamber for changing the angle of attack of the plasma.

[0025] Further, the airflow processing equipment includes a pressure diffuser pipe, a cooler and a vacuum tank group connected in sequence;

[0026] A pressure expansion pipe, one end of which is located in the plasma chamber and is used to expand and reduce the speed of the plasma;

[0027] A cooler, used to cool down the plasma after pressure expansion and speed reduction;

[0028] Vacuum tank set, used to temporarily store cooled plasma.

[0029] Furthermore, the nozzle is a rectangular nozzle, the outlet size of which is 80 mm×180 mm, the roar size of which is 80 mm×100 mm, and the nominal Mach number of the airflow is 2.0.

[0030] The technical effect of adopting the above further scheme is: the system sequentially expands the pressure, reduces the speed, cools and temporarily stores the plasma, making it easier to manage the plasma. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1This is a partial structural diagram of the system;

[0032] Figure 2 A schematic diagram of a receiving antenna receiving signals at different positions;

[0033] Figure 3 It is a schematic diagram of the pneumatic feeding mechanism;

[0034] Figure 4 This is a physical schematic diagram of the electromagnetic wave shielding test chamber;

[0035] Figure 5 6G frequency radiation diagram under three plasma densities in the embodiment.

[0036] Among them: 1. Electromagnetic wave shielding test chamber; 2. Plasma chamber; 3. Optical platform; 4. Arc guide rail; 5. Receiving antenna; 6. Transmitting antenna; 7. Wave-transmitting window. DETAILED DESCRIPTION

[0037] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0038] like Figure 1 and Figure 2 As shown, the electromagnetic radiation pattern test system for high-frequency induction plasma equipment includes high-frequency induction plasma equipment, an electromagnetic wave shielding test cabin 1, a vector network analyzer, a host computer and an airflow processing device;

[0039] The high-frequency induction plasma device comprises a high-frequency plasma heater, a nozzle and a plasma chamber 2; the output end of the high-frequency plasma heater is connected to one end of the plasma chamber 2 through the nozzle; the other end of the plasma chamber 2 is connected to the airflow processing device; at least one side of the plasma chamber 2 is provided with an observation window; a transmitting antenna 6 is provided in the plasma chamber 2; the transmitting antenna 6 is connected to the signal transmitting end of the vector network analyzer;

[0040] The electromagnetic wave shielding test chamber 1 is provided with a wave-transmitting window 7, and an arc-shaped guide rail 4 is provided in the electromagnetic wave shielding test chamber 1. A receiving antenna 5 is slidably provided on the arc-shaped guide rail 4, and the receiving antenna 5 is connected to the signal receiving end of the vector network analyzer; the center of the arc-shaped guide rail 4 is the position of the transmitting antenna 6;

[0041] The arc-shaped guide rail 4 is used to adjust the signal receiving azimuth of the receiving antenna 5;

[0042] The receiving antenna 5 is used to receive the signal of the transmitting antenna 6 passing through the plasma through the observation window and the wave-transmitting window 7, and send the received signal to the vector network analyzer; the plasma is the medium to be tested;

[0043] A vector network analyzer, used for testing S21 parameters according to the signal from the receiving antenna 5;

[0044] The host computer is used to calculate the electromagnetic radiation pattern of the high-frequency induction plasma device according to the S21 parameters obtained by the vector network analyzer test.

[0045] In this embodiment, the movement of the receiving antenna 5 on the arc-shaped guide rail 4 is driven by a stepper motor, ensuring that the angle of each movement of the receiving antenna 5 is the same and that the distance from the transmitting antenna 6 remains unchanged. Observation windows are provided on both sides of the plasma chamber 2, and the other observation window is used to record the plasma ablation process and measure the plasma ablation surface temperature. Vector network analyzers and other similar test instruments can be placed in the electromagnetic wave shielding test chamber 1 to ensure stability.

[0046] High-frequency plasma generators are usually made of a coil wound with a metal (such as a copper tube) on the outside of a quartz tube, so that the high-frequency current supplied by an external power source couples with the plasma in the discharge tube through the magnetic field generated by the coil. Under the condition that the working gas in the generator has been broken down (ignited) and can conduct electricity, the alternating electric field induced by the alternating magnetic field generated by the excitation current flowing through the coil will cause current in the conductive gas and generate Joule heat. When the conditions are appropriate, the discharge will be able to continue and continuously heat the low-temperature working gas fed into the generator to form a plasma flow. High-frequency plasma generators can provide pure, long-running high-enthalpy plasma flow.

[0047] like Figure 4 As shown, the electromagnetic wave shielding test cabin 1 is a metal room, the outer wall of the metal room is wrapped with aluminum foil and grounded; the inner wall of the metal room is covered with conical absorbing material; doors for passage are provided on both sides of the metal room; the electromagnetic wave shielding test cabin 1 is in contact with the plasma cabin 2, and an inward opening door is provided on the contacting side, and the wave-transmitting window is located on the inward opening door.

[0048] The size of the metal room is 2.24m×1.9m×2.2m; the thickness of the aluminum foil is 0.001m; the cone height of the conical absorbing material is 0.2m, the working frequency band is 2-40GHz, and the reflectivity is maintained below -50dB; the size of the inner door is 1m×1.3m; the size of the wave-transmitting window 7 is 0.48m×0.48m, and it can transmit electromagnetic waves in the L, S, C, X, Ku, K, and Ka bands. The radius of the arc-shaped guide rail 4 is 2m, the chord length is 2m, and the arc span is plus or minus 60 degrees.

[0049] In the specific implementation process, the size, shape, track length, antenna height, and frequency shielding range of the electromagnetic wave shielding test chamber 1 can also be adjusted for different high-frequency induction plasma equipment. Similarly, the corresponding parameters of the wave-transmitting window 7 and the arc-shaped guide rail 4 can also be adjusted according to actual conditions, and it is only necessary to ensure that the transmitting antenna 6 is located at the center of the arc-shaped guide rail 4.

[0050] An optical platform 3 for placing the arc-shaped guide rail 4 is also provided in the electromagnetic wave shielding test chamber 1 . The optical platform 3 is calibrated by a laser level so that the arc-shaped guide rail 4 remains horizontal.

[0051] In the specific implementation process, Figure 3 As shown, a pneumatic feeding mechanism is provided in the plasma chamber 2. The system can test the plasma alone. At this time, the pneumatic feeding mechanism includes a paddle that can swing up and down, and the angle of attack of the plasma is adjusted by adjusting the angle of the paddle. The system can also place a target device (such as a local structure of an aircraft) in the plasma chamber 2 to test the plasma after passing through the target device. At this time, the target device acts as a paddle, and the pneumatic feeding mechanism only needs to be able to adjust the angle of the target device. The angle of attack of the plasma is adjusted by adjusting the angle of the target device. In the field of mechanics, there are many devices that can adjust the angle of an object, which will not be described here.

[0052] The airflow processing equipment includes a pressure diffuser pipe, a cooler and a vacuum tank group connected in sequence;

[0053] A pressure expansion pipe, one end of which is located in the plasma chamber 2 and is used to expand and reduce the speed of the plasma;

[0054] A cooler, used to cool down the plasma after pressure expansion and speed reduction;

[0055] Vacuum tank set, used to temporarily store cooled plasma.

[0056] The nozzle is a geometric channel that forms the required flow field for high-temperature and high-pressure gas. For test models of different structures and sizes, and referring to the thermal environment parameters to be simulated, special nozzles of different types and sizes are selected and used. The arc wind tunnel is equipped with two types of nozzles: axisymmetric conical nozzles and rectangular nozzles. The former can provide a three-dimensional flow field and conduct experimental research on rotating body models or wedge-shaped two-dimensional models; the latter compresses the limited hot air flow into a two-dimensional thin layer and makes it flow through a two-dimensional flat plate model. It is an effective test method to maximize the use of energy when the hot air flow is limited. In this embodiment, the nozzle adopts a rectangular nozzle with an outlet size of 80mm×180mm, a roar size of 80mm×100mm, and a nominal Mach number of the air flow of 2.0.

[0057] In the specific implementation process, the antenna pattern calculation formula is: gain pattern in the test environment = S21 parameters of each angle measured by the sliding receiving antenna 5 - S21 parameters of each angle measured by the calibration antenna + standard gain of the calibration antenna.

[0058] In one embodiment of the present invention, the test high-frequency induction plasma wind tunnel is started according to the test state setting in Table 1, the flow field begins to be established, and after the flow field is stabilized, the receiving antenna 5 begins to slide along the arc-shaped guide rail 4 in sequence according to the set angle range and starts the test work.

[0059] Table 1: Test items for interaction between plasma and electromagnetic waves

[0060]

[0061]

[0062] The high-frequency induction wind tunnel produces an electron density of 10 10 -10 12 cm -3 There are three different electron density distributions between them. The experimental test data include S11 parameters (return loss), input impedance, S21 parameters and antenna radiation pattern in the presence or absence of plasma. The polarization modes are V / H polarizations, and the test frequency band is the antenna operating frequency of 4-26GHz. Figure 5 As shown, the radiation pattern is obtained by moving along the track to obtain the S21 parameters at different angles and comparing the gain with the standard antenna.

[0063] In conclusion, the present invention can be disassembled and moved to facilitate adaptation to the location where new media are generated, thereby solving the problem that the new media cannot be moved into the darkroom, resulting in the inability to perform electromagnetic radiation pattern testing in the high-frequency induction wind tunnel. In addition, by setting up an arc guide rail, the system allows the receiving antenna to measure the S21 parameters at different angles with the transmitting antenna as the center of the circle. The angle of each movement of the receiving antenna can be the same and the distance from the transmitting antenna can be kept constant. Finally, the radiation pattern of the transmitting antenna is formed by summarizing the results of each angle.

Claims

1. An electromagnetic pattern test system for high-frequency induction plasma equipment, characterized in that: Including high-frequency induction plasma equipment, electromagnetic wave shielding test chamber, vector network analyzer, host computer and airflow processing equipment; The high-frequency induction plasma device comprises a high-frequency plasma heater, a nozzle and a plasma chamber; the output end of the high-frequency plasma heater is connected to one end of the plasma chamber through the nozzle; the other end of the plasma chamber is connected to the airflow processing device; at least one side of the plasma chamber is provided with an observation window; a transmitting antenna is provided in the plasma chamber; the transmitting antenna is connected to the signal transmitting end of the vector network analyzer; A wave-transmitting window is provided on the electromagnetic wave shielding test cabin, an arc-shaped guide rail is provided in the electromagnetic wave shielding test cabin, a receiving antenna is slidably provided on the arc-shaped guide rail, and the receiving antenna is connected to the signal receiving end of the vector network analyzer; the center of the arc-shaped guide rail is the position of the transmitting antenna; The arc-shaped guide rail is used to adjust the signal receiving azimuth of the receiving antenna; A receiving antenna, used for receiving the signal transmitted through the plasma by the transmitting antenna through the observation window and the wave-transmitting window, and sending the received signal to the vector network analyzer; Vector network analyzer for testing S21 parameters based on the signal from the receiving antenna; The host computer is used to calculate the electromagnetic radiation pattern of the high-frequency induction plasma device according to the S21 parameters obtained by the vector network analyzer test.

2. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 1, characterized in that: The electromagnetic wave shielding test cabin is a metal room, the outer wall of the metal room is wrapped with aluminum foil and grounded; the inner wall of the metal room is covered with conical absorbing material; doors for passage are provided on both sides of the metal room; the electromagnetic wave shielding test cabin is in contact with the plasma cabin, and an inward-opening door is provided on the contacting side, and the wave-transmitting window is located on the inward-opening door.

3. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 2, characterized in that: The dimensions of the metal room are 2.24m×1.9m×2.2m; the thickness of the aluminum foil is 0.001m; the cone height of the conical absorbing material is 0.2m, and the working frequency band is 2-40GHz; the dimensions of the inner door are 1m×1.3m; and the dimensions of the wave-transmitting window are 0.48m×0.48m.

4. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 1, characterized in that: The radius of the arc guide is 2m, the chord length is 2m, and the arc span is plus or minus 60 degrees.

5. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 1, characterized in that: The electromagnetic wave shielding test chamber is also provided with an optical platform for placing the arc-shaped guide rail. The optical platform is calibrated by a laser level to keep the arc-shaped guide rail level.

6. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 1, characterized in that: A pneumatic feeding mechanism is provided in the plasma chamber to change the angle of attack of the plasma.

7. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 1, characterized in that: The airflow processing equipment includes a pressure diffuser pipe, a cooler and a vacuum tank group connected in sequence; A pressure expansion pipe, one end of which is located in the plasma chamber and is used to expand and reduce the speed of the plasma; A cooler, used to cool down the plasma after pressure expansion and speed reduction; Vacuum tank set, used to temporarily store cooled plasma.

8. The electromagnetic pattern test system for high-frequency induction plasma equipment according to claim 1, characterized in that: The nozzle is a rectangular nozzle with an outlet size of 80mm×180mm, a roar size of 80mm×100mm, and a nominal Mach number of the airflow of 2.0.

Images