A high-frequency and high-power test platform

Abstract

The invention discloses a high-frequency and high-power test platform, which is characterized by comprising an inner-cavity conductor (1), an outer-cavity conductor (2), an upper end cover (3) of the cavity, a lower end cover (4) of the cavity, a capacitance cup (5) and a device-to-be-tested connection port (6); wherein the inner-cavity conductor (1) is coaxially arranged in the outer-cavity conductor (2); the upper end of the inner-cavity conductor (1) and the upper end of the outer-cavity conductor (2) are connected to form a short-circuit path through the upper end cover (3) of the cavity; the bottom end of the outer-cavity conductor (2) is connected to the lower end cover (4); and the inner and outer conductors and the upper and lower end covers form an internal closed area forming a quarter-wavelength coaxial resonant cavity; the capacitance cup (5) is arranged outside the side wall of the inner-cavity conductor (1); the device-to-be-tested connection port (6) is arranged on the side wall of the outer-cavity conductor (2) and satisfies a coaxial constraint relationship with the capacitance cup (5); and a vacuum port (7) is provided on the lower end cover (4).

Description

Technical Field

[0001] The present invention belongs to the technical field of particle accelerators, and in particular relates to a high-frequency and high-power testing platform. Background Art

[0002] The high-frequency and high-power test platform was developed to meet the high-power testing needs of equipment related to the storage ring high-frequency system of the high-energy synchrotron radiation light source project, a major national scientific and technological infrastructure project, and can be widely used in high-power testing of electric vacuum microwave high-frequency devices with an average power of hundreds of kilowatts.

[0003] Electrovacuum microwave high-frequency, high-power devices are widely used in particle accelerators, broadcasting, communications, radar, and other fields. In recent years, as these fields advance towards higher energies and higher performance, the power requirements for these devices have also increased. Common electrovacuum microwave high-frequency devices in particle accelerators include high-power input couplers, high-power microwave windows, high-order mode absorbers, and superconducting accelerating cavities. To meet the demands of high-current and high-energy applications, two cutting-edge accelerator development trends, these devices typically achieve peak power levels in the megawatt range, with average power levels reaching hundreds of kilowatts. All high-power electrovacuum microwave high-frequency devices must undergo high-power testing before commissioning. Microwave power is used to remove dust and metal particles from the device's internal surfaces to ensure stable operation at rated power. Furthermore, testing verifies that the device's performance parameters meet design specifications at high power. Testing these devices requires both high vacuum and high power, necessitating a high-power test platform with multiple functions, including establishing a microwave matching transmission path, creating a high vacuum environment, supporting the microwave device under test, and providing necessary cooling.

[0004] At present, the test platforms commonly used for high-power testing of high-power microwave windows, high-power input couplers and other devices at home and abroad are rectangular waveguide type (reference: M. Stirbet., IECampisi, GK Davis, M. Drury, T. Powers, G. Myneni et al. "HIGH POWER RF TESTS ON FUNDAMENTAL POWER COUPLERS FOR THE SNS PROJECT", Proceedings of EPAC 2002, Paris, France), cylindrical resonant cavity type (reference: ENS Schmierer, KCDChan, DC Gautier, JG Gioia et al. "High-Power Testing of the APT Power coupler", XX International Linac Conference, Monterey, California) and capacitor loading type (reference patent: A high-power microwave test platform, ZL201310295720.0, inventors: Huang Tongming, Ma Qiang, Pan Weimin, etc.). The structural schematic diagrams of the above three test platforms are shown in the attached figure. Figures 1 to 3 As shown in the figure, the ports connected to the device under test are located on the upper end face of the wide side of the rectangular waveguide, the side wall end face of the cylindrical resonant cavity, and the upper end face of the capacitor-loaded resonant cavity.

[0005] The test system consisting of the DUT and the test platform must first achieve good microwave matching transmission. This typically requires the fundamental mode resonant frequency of the test platform to be consistent with the operating frequency of the DUT. This results in a fatal drawback for existing commonly used rectangular waveguide and cylindrical resonant cavity test platforms at frequencies below 500 MHz: the test platform's bulk increases the difficulty of fabricating, installing, and operating the test platform, rendering them unusable at low frequencies. Capacitor-loaded test platforms, on the other hand, can lower the fundamental mode resonant frequency of the cavity by adjusting the loading capacitor. This offers the advantages of small size, wide operating bandwidth, and easy adjustment at low frequencies. However, this type of test platform requires the DUT to be integrally connected to the inner conductor of its connection port; otherwise, power cannot be coupled into the cavity. Therefore, if the DUT's inner conductor does not contain a structure that allows for direct, integral connection, preventing electrical contact, this type of test platform cannot be used for testing. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention aims to provide a high-frequency and high-power test platform.

[0007] The technical solution of the present invention is:

[0008] A high-frequency and high-power test platform, characterized by comprising a cavity inner conductor 1, a cavity outer conductor 2, a cavity upper end cover 3, a cavity lower end cover 4, a capacitor cup 5 and a device under test connection port 6; wherein,

[0009] The inner-cavity conductor 1 is coaxially arranged in the outer-cavity conductor 2. The upper end of the inner-cavity conductor 1 and the upper end of the outer-cavity conductor 2 are connected through the cavity upper end cover 3 to form a short-circuit. The bottom end of the outer-cavity conductor 2 is connected to the cavity lower end cover 4. The inner-cavity conductor 1, the outer-cavity conductor 2, the cavity upper end cover 3 and the cavity lower end cover 4 form an internal closed area forming a quarter-wavelength coaxial resonant cavity.

[0010] The capacitor cup 5 is arranged outside the side wall of the conductor 1 in the cavity; the device under test connection port 6 is arranged on the side wall of the conductor 2 outside the cavity and satisfies a coaxial constraint relationship with the capacitor cup 5;

[0011] A vacuum port 7 is provided on the lower end cover 4 of the cavity for connecting to a vacuum pump.

[0012] Furthermore, the capacitor cup 5 is close to the bottom end of the conductor 1 in the cavity.

[0013] Furthermore, the capacitor cup 5 is a cylindrical structure with one end open, and the opening of the cylindrical structure faces the DUT connection port 6 ; the DUT connection port 6 is a cylindrical structure with both ends open.

[0014] Furthermore, the DUT connection port 6 is a height-adjustable DUT connection port; by adjusting the protruding height of the DUT connection port 6 on the outer side wall of the conductor 2 outside the cavity, the insertion depth of the conductor inside the DUT is optimized.

[0015] Furthermore, it includes two capacitor cups 5, which are symmetrically arranged on the outside of the side wall of the conductor 1 in the cavity; two DUT connection ports 6 are symmetrically arranged on the side wall of the conductor 2 outside the cavity, and meet a coaxial constraint relationship with the capacitor cups 5.

[0016] Furthermore, the vacuum port 7 is connected to the lower end cover 4 of the cavity through a microwave shielding structure 8; the microwave shielding structure 8 is a hollow petal-shaped structure with six rounded semicircles surrounding a central circle.

[0017] Furthermore, the side walls and bottom of the conductor 1 in the cavity are a double-layer structure, the side wall above the device under test connection port 6 of the conductor 2 in the cavity is a double-layer structure, and a water inlet pipe 9 is provided inside the conductor 1 in the cavity. The water inlet pipe 9 is connected to the double-layer structure at the bottom of the conductor 1 in the cavity, and the water outlet pipe 10 is connected to the double-layer structure of the side wall of the conductor 1 in the cavity through the upper end cover 3 of the cavity.

[0018] Furthermore, a spiral fin structure is adopted in the sandwich of the double sandwich structure.

[0019] Furthermore, the conductor 2 outside the cavity is made of stainless steel and the inner wall is copper-plated; the conductor 1 inside the cavity is made of oxygen-free copper.

[0020] The advantages of the present invention are as follows:

[0021] The platform provided by the present invention has a compact structure and a small size. The device to be tested is easy to install on the test bench and its inner conductor does not need to be directly connected to the test bench. It can also pass microwave powers with an average power of hundreds of kilowatts with high matching and low loss, and can establish a high vacuum environment. Therefore, it can be used for high-power testing of electric vacuum microwave high-frequency and high-power devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a rectangular waveguide type test platform.

[0023] Figure 2 It is a cylindrical resonant cavity test platform.

[0024] Figure 3 It is a capacitor loading test platform.

[0025] Figure 4 Schematic diagram of the quarter-wavelength coaxial resonant cavity structure.

[0026] Figure 5 This is the schematic diagram of the quarter-wavelength coaxial resonant cavity circuit;

[0027] (a) is the parameter circuit diagram; (b) is the distribution diagram of voltage and current amplitude along the way.

[0028] Figure 6 This is a cross-sectional view of the high-frequency and high-power test platform of the present invention.

[0029] Figure 7 It is a schematic diagram of the three-dimensional structure of the high-frequency and high-power test platform of the present invention.

[0030] Figure 8 This is the transmission characteristic curve of the high-frequency and high-power test platform of the present invention. DETAILED DESCRIPTION

[0031] The present invention will now take the development of a 166MHz-250kW coupler high-power test platform as a specific embodiment to introduce the technical solution and implementation process of the present invention in detail.

[0032] The main body of the test platform of the present invention is a quarter-wavelength coaxial resonant cavity, and its structural diagram is shown in the attached figure. Figure 4 As shown, the circuit schematic is shown in the attached Figure 5As shown. The quarter-wavelength coaxial resonant cavity, evolved from a coaxial transmission line, is essentially a transverse electromagnetic mode resonant cavity with no frequency selectivity for electromagnetic waves. This ensures that at low frequencies, it can achieve a smaller volume than rectangular waveguide and cylindrical resonant cavity test platforms. Therefore, it is often used in low-frequency (100MHz to 200MHz) resonant cavities. The inner and outer conductors at one end of the cavity are short-circuited, and the inner conductor length is approximately one-quarter of the wavelength corresponding to the fundamental mode (TM010) resonant frequency. This creates an open circuit at the end of the inner conductor, resulting in a maximum magnetic field at the short circuit and a maximum electric field at the open circuit.

[0033] The present invention designs the connection port of the device under test near the open road surface, and completes the structural optimization design of the 166MHz-250kW high power test platform through electromagnetic transmission simulation and electromagnetic-thermal coupling simulation optimization, as shown in the attached figure. Figure 6 and attached Figure 7 As shown. The main structure includes: an inner-cavity conductor 1, an outer-cavity conductor 2, a cavity upper end cover 3, a cavity lower end cover 4, a capacitor cup 5 and a device under test connection port 6. Among them, the inner-cavity conductor 1 is coaxially arranged in the outer-cavity conductor 2, and the internal closed area formed by the inner-cavity conductor 1, the outer-cavity conductor 2, the upper end cover 3 and the lower end cover 4 constitutes a quarter-wavelength coaxial resonant cavity (the length of the inner-cavity conductor 2 is about one-quarter of the wavelength corresponding to the resonant frequency. According to the impedance theory of the transmission line, the distance from the short-circuit surface to the open surface is converted). The capacitor cup 5 is located on the outside of the side wall of the inner-cavity conductor 1 and is close to the end of the quarter-wavelength inner conductor. The capacitor cup 5 is a cylindrical tube structure with one end open, and the open end faces the device under test connection port 6; by optimizing the inner and outer wall diameters, heights and cup edge chamfers of the capacitor cup 5, it can be ensured that the inner conductor of the device under test can achieve good exchange of electromagnetic energy without electrical contact with the test platform. The DUT connection port 6 is located on the side wall of the outer conductor 2 of the cavity. It is a cylindrical tube structure with two ends open and satisfies the coaxial constraint relationship with the capacitor cup 5. By changing the height of the cylindrical tube in the DUT connection port 6, that is, the height of the protrusion outside the side wall of the outer conductor 2, the insertion depth of the inner conductor of the DUT can be optimized, thereby achieving the best matching transmission of the entire test system (upstream DUT-test platform-downstream DUT) at the operating frequency point. The optimized transmission characteristic curve is shown in the attached figure. Figure 8As shown. A vacuum port 7 is designed on the lower end cover 4 of the cavity for connecting a vacuum pump to establish a high vacuum environment for the entire test system. In order to ensure that microwave leakage meets safety requirements, a microwave shielding structure 8 is carefully designed at the connection between the vacuum port 7 and the lower end cover 4 of the cavity. It is a hollow petal-shaped structure with 6 rounded semicircles surrounding a central circle. By optimizing the diameters of the semicircles and the central circle, the best balance is achieved between the vacuum rate and microwave shielding. In addition, in order to meet the test power level of more than 300kW of continuous wave, the strong magnetic field area of the entire test platform is fully water-cooled. The side walls and bottom of the conductor 1 inside the cavity, as well as the side walls above the port 6 of the conductor 2 outside the cavity, adopt a double-layer structure. The spiral fin structure is used in the interlayer to enhance the heat exchange and cooling effect. The water inlet pipe 9 is inserted from the inside of the conductor 1 inside the cavity, and the water outlet pipe 10 is located at the upper end cover 3 of the cavity. Water circulates through the double-layer structure of the inner conductor 1. To meet mechanical strength requirements, the outer conductor 2 of the cavity is made of stainless steel, and its inner wall is copper-plated to reduce high-frequency heat loss. The inner conductor 1 of the cavity is made of oxygen-free copper, ensuring low high-frequency heat loss while achieving good heat exchange. Through cooling and material optimization, the entire test platform can achieve a continuous wave test power level of hundreds of kilowatts.

[0034] The above 166MHz-250kW coupler high power test platform was successfully applied to the test of 166MHz high power input coupler of the high frequency system of the high energy synchrotron radiation light source project. The whole test system has a good transmission matching at the working frequency point (measured: S11 <-30dB@166.6MHz, see attached Figure 8 The test curve value in the figure shows that the entire test system has withstood the long-term stress test of 250kW traveling waves. The maximum temperature rise of the high-frequency and high-power test platform of the present invention is only 22°C, which is in good agreement with the simulation results.

[0035] While specific embodiments of the present invention have been disclosed for illustrative purposes, intended to facilitate understanding and implementation of the present invention, those skilled in the art will appreciate that various substitutions, variations, and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the present invention should not be limited to the disclosure of the preferred embodiments, and the scope of protection claimed in the present invention shall be determined by the scope of the claims.

Claims

1. A high-frequency and high-power test platform, characterized in that: The device comprises an inner cavity conductor (1), an outer cavity conductor (2), an upper cavity end cover (3), a lower cavity end cover (4), two capacitance cups (5) and two device-to-be-tested connection ports (6); wherein the inner cavity conductor (1) is coaxially arranged in the outer cavity conductor (2); the upper end of the inner cavity conductor (1) and the upper end of the outer cavity conductor (2) are connected via the upper cavity end cover (3) to form a short-circuit; the bottom end of the outer cavity conductor (2) is connected to the lower cavity end cover (4); and the inner cavity conductor (1), the outer cavity conductor (2), the upper cavity end cover (3) and the lower cavity end cover (4) form an internal closed area forming a quarter-wavelength coaxial resonant cavity; Two capacitor cups (5) are symmetrically arranged on the outside of the side wall of the conductor (1) in the cavity; two device-to-be-tested connection ports (6) are symmetrically arranged on the side wall of the conductor (2) outside the cavity and satisfy a coaxial constraint relationship with the capacitor cups (5); the capacitor cups (5) are cylindrical structures with one end open, and the opening of the cylindrical structure faces the device-to-be-tested connection port (6); the device-to-be-tested connection port (6) is a cylindrical structure with two ends open; A vacuum port (7) is provided on the lower end cover (4) of the cavity for connecting to a vacuum pump.

2. The high-frequency and high-power test platform according to claim 1, characterized in that: The capacitor cup (5) is close to the bottom end of the conductor (1) in the cavity.

3. The high-frequency and high-power test platform according to claim 1 or 2, characterized in that: The device under test connection port (6) is a height-adjustable device under test connection port; by adjusting the protrusion height of the device under test connection port (6) outside the side wall of the conductor (2) outside the cavity, the insertion depth of the conductor inside the device under test is optimized.

4. The high-frequency and high-power test platform according to claim 1, characterized in that: The vacuum port (7) is connected to the lower end cover (4) of the cavity through a microwave shielding structure (8); the microwave shielding structure (8) is a hollow petal-shaped structure with six rounded semicircles surrounding a central circle.

5. The high-frequency and high-power test platform according to claim 1, characterized in that: The side wall and bottom of the conductor (1) in the cavity are double-layer structures, the side wall above the device-to-be-tested connection port (6) of the conductor (2) in the cavity is double-layer structure, a water inlet pipe (9) is provided inside the conductor (1) in the cavity, the water inlet pipe (9) is connected to the double-layer structure at the bottom of the conductor (1) in the cavity, and the water outlet pipe (10) is connected to the double-layer structure of the side wall of the conductor (1) in the cavity through the upper end cover (3) of the cavity.

6. The high-frequency and high-power test platform according to claim 5, characterized in that: The double-sandwich structure has a spiral fin structure in the sandwich.

7. The high-frequency and high-power test platform according to claim 6, characterized in that: The outer conductor (2) of the cavity is made of stainless steel, and the inner wall thereof is subjected to a stainless steel copper plating treatment; the inner conductor (1) of the cavity is made of oxygen-free copper.

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