Half cavity directly coupled magnetic alloy high frequency cavity

Abstract

This application provides a half-cavity directly coupled magnetic alloy high-frequency cavity, relating to the field of ion accelerator technology. The magnetic alloy high-frequency cavity is connected to a radio frequency power source. The magnetic alloy high-frequency cavity includes: a cavity body comprising two symmetrically arranged half-cavities; a vacuum pipe disposed inside the cavity body and connecting the two half-cavities; multiple magnetic alloy rings disposed in a single half-cavity and coaxially arranged with the vacuum pipe, the multiple magnetic alloy rings being parallel to each other; a coupling device for electromagnetically coupling the multiple magnetic alloy rings located in a single half-cavity to form an overall load unit; and an impedance transformation unit disposed on one side of each half-cavity and electrically connected to the overall load unit, used to transform the impedance of the overall load unit to an impedance matching the characteristic impedance of an external feed line, so as to connect to the radio frequency power source through the external feed line. This application, through a half-cavity fully coupled design, eliminates inter-path coupling, ensuring that the port impedance test value is consistent with the actual value, and is easy to adjust.

Description

Technical Field

[0001] This application relates to the field of ion accelerator technology, and in particular to a semi-cavity direct-coupled magnetic alloy high-frequency cavity. Background Technology

[0002] In multi-ion synchrotrons, the magnetic alloy-loaded high-frequency cavity is the core component for generating the required accelerating voltage. It can accelerate various charged ions and meet the requirements of single-cycle energy variation. This cavity has the characteristics of wide bandwidth and fast response.

[0003] Synchrotron high-frequency cavities operate in a swept-frequency mode, with a high-end frequency to low-end frequency ratio exceeding 8. Common magnetic alloy-loaded synchrotron ring high-frequency cavities have a peak cavity voltage of 2kV~4kV and typically consist of eight magnetic rings, divided into left and right halves. Each half-cavity usually contains four magnetic alloy rings and is driven by a solid-state broadband RF power source. To improve power transmission efficiency and achieve impedance matching, two of the magnetic alloy rings are commonly electromagnetically coupled to form an equivalent load, which is then connected to the RF power source output via an external impedance transformer—this is known as two-way coupling within the half-cavity.

[0004] However, this traditional two-way coupling design has the following drawbacks: due to the mutual coupling between the two paths, the impedance value of each path obtained by network analysis is lower than the actual impedance value. The greater the coupling, the greater the deviation. The power coupling coefficient is proportional to the frequency and the permeability of the alloy material. The permeability of the magnetic alloy rings available domestically is relatively high, resulting in a lower test impedance than the actual impedance at high-end operating frequencies. The circuit designed according to the test values ​​shows good test performance with a voltage standing wave ratio (VSWR) below 1.2. However, under actual operating conditions with simultaneous power applied to both paths, the actual VSWR reaches 1.5 to 1.6, leading to a significant decrease in power transmission efficiency and failing to meet the requirements for high-efficiency acceleration. Summary of the Invention

[0005] In view of the above problems, this application provides a semi-cavity direct-coupled magnetic alloy high-frequency cavity.

[0006] According to an embodiment of this application, a half-cavity direct-coupled magnetic alloy high-frequency cavity is provided for connection to a radio frequency power source, comprising: a cavity body including two symmetrically arranged half-cavities; a vacuum pipe disposed inside the cavity body and connecting the two half-cavities; multiple magnetic alloy rings disposed in a single half-cavity and coaxially arranged with the vacuum pipe, the multiple magnetic alloy rings being parallel to each other; a coupling device for electromagnetically coupling the multiple magnetic alloy rings located in a single half-cavity to form an overall load unit; and an impedance transformation unit disposed on one side of each half-cavity and electrically connected to the overall load unit for transforming the impedance of the overall load unit into an impedance matching the characteristic impedance of an external feed line, so as to connect to the radio frequency power source through the external feed line.

[0007] According to an embodiment of this application, the coupling device includes a coupling line that passes sequentially through the inner wall of a plurality of magnetic alloy rings and the two ends of the coupling line are connected to an impedance transformation unit.

[0008] According to an embodiment of this application, the impedance transformation unit includes a single-ended to balanced converter and an impedance transformer; the input terminal of the single-ended to balanced converter is connected to an external feed line, and the output terminal is connected to the input terminal of the impedance transformer, for converting the single-ended radio frequency signal transmitted by the external feed line into a balanced radio frequency signal; the output terminal of the impedance transformer is connected to both ends of the coupling line, and the impedance transformer is used to receive the balanced radio frequency signal and perform impedance transformation on the balanced radio frequency signal, and transform the impedance of the overall load unit into an impedance that matches the characteristic impedance of the external feed line through the balanced radio frequency signal after impedance transformation.

[0009] According to an embodiment of this application, the impedance transformation unit further includes an impedance matching circuit, which is connected to the impedance transformer and the external feed line respectively, and is used to further match the impedance after transformation by the impedance transformer to the characteristic impedance of the external feed line.

[0010] According to an embodiment of this application, multiple magnetic alloy rings are fixed in a semi-cavity by a support member; the support member includes: multiple fixing plates, which are evenly distributed along the circumference of the outer edge of the magnetic alloy rings and perpendicular to the magnetic alloy rings, and the two ends of each fixing plate are fixedly connected to the two ends of the semi-cavity respectively; and a plurality of connecting plates, which are evenly distributed along the circumference of the magnetic alloy rings and parallel to the magnetic alloy rings, with one end of the connecting plate fixedly connected to the inner wall of the magnetic alloy rings and the other end fixedly connected to the fixing plate.

[0011] According to an embodiment of this application, the magnetic alloy ring is a ring-shaped magnetic core formed by winding magnetic alloy strip.

[0012] According to embodiments of this application, the full-band voltage standing wave ratio of the magnetic alloy high-frequency cavity is less than 1.2.

[0013] According to an embodiment of this application, the impedance transformation ratio of the impedance transformation unit is designed as the ratio of the characteristic impedance of the external feeder to the equivalent impedance of the overall load unit.

[0014] According to an embodiment of this application, the impedance transformation ratio of the impedance transformation unit is 1:9.

[0015] According to an embodiment of this application, the impedance of a single magnetic alloy ring at the working center frequency of the magnetic alloy high-frequency cavity is 80Ω~130Ω.

[0016] The semi-cavity direct-coupled magnetic alloy high-frequency cavity provided in this application has at least the following technical advantages:

[0017] 1. This application uses a coupling device to uniformly couple all the magnetic alloy rings located in a half-cavity, making the half-cavity act as a single load port, thus eliminating the complex internal coupling effects caused by the traditional two-way coupling of half-cavities. The port impedance of the half-cavity is the impedance of the entire load unit, and the measured port impedance value is consistent with the actual value, making the actual test results true, reliable, and highly repeatable, providing accurate input parameters for subsequent design.

[0018] 2. In this application, since the impedance characteristics are clear, the appropriate impedance transformer can be accurately calculated and selected directly based on the impedance of the overall load unit and the impedance of the target system. The size of the magnetic alloy ring can be adjusted through actual test values. The matching process is changed from "complex debugging" to "calculation and selection", which greatly simplifies the engineering design and improves the success rate and efficiency. Attached Figure Description

[0019] The above-mentioned contents, other objects, features and advantages of this application will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0020] Figure 1 This schematic diagram illustrates the structure of a high-frequency cavity for a magnetic alloy-loaded synchronization ring in the prior art.

[0021] Figure 2 A top view of a half-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is schematically shown;

[0022] Figure 3 A schematic diagram of a semi-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is shown.

[0023] Figure 4 A schematic cross-sectional view of a half-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is shown.

[0024] Figure 5 The equivalent circuit diagram of a half-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is schematically shown;

[0025] Figure 6 The schematic diagram illustrates the circuit principle of an impedance transformation unit according to an embodiment of this application.

[0026] Reference numerals in the attached drawings: 1-Cavity body; 2-Half-cavity; 3-Vacuum pipe; 4-Magnetic alloy ring; 5-Coupled device; 6-Impedance transformation unit; 7-Fixing plate; 8-Connecting plate. Detailed Implementation

[0027] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0029] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0030] Figure 1 The diagram schematically illustrates the structure of a high-frequency cavity for a magnetic alloy-loaded synchronous ring in the prior art.

[0031] In related technologies, the high-frequency cavity of a synchrotron operates in a frequency-sweeping mode, with a high-end frequency to low-end frequency ratio exceeding 8. A common magnetic alloy-loaded synchrotron ring high-frequency cavity has a peak cavity voltage of 2kV~4kV and typically consists of eight magnetic alloy rings, divided into left and right half-cavities. Each half-cavity typically contains four magnetic alloy rings and is driven by a solid-state broadband power source. Figure 1 As shown, in order to improve power transmission efficiency and achieve impedance matching, it is common practice to electromagnetically couple two of the magnetic alloy rings 4 to form an equivalent load, and then connect it to the power source output through an external impedance transformer, i.e., two-way coupling of half cavity 2.

[0032] The impedance of a single magnetic alloy ring 4 at the design center frequency of 3.5MHz is approximately 100Ω. The equivalent load of only two coupled magnetic alloy rings 4 is approximately 200Ω. To achieve the 50Ω impedance required for matching the standard feeder, an impedance transformer with an impedance transformation ratio of 1:4 is needed to convert the impedance to 50Ω. However, during impedance testing, the other two uncoupled magnetic alloy rings 4 will experience unpredictable mutual inductance with the coupled portion through the spatial magnetic field. This results in the impedance Z_in seen from the port being smaller than the actual impedance value. The greater the coupling degree, the greater the deviation. The power coupling coefficient is proportional to the frequency and the permeability of the alloy material. The permeability of the magnetic alloy rings 4 available domestically is relatively high, resulting in a 25%~30% lower test impedance than the actual impedance at high-end operating frequencies. The matching circuit designed according to the test values ​​showed good test performance, with a voltage standing wave ratio below 1.2. However, after connecting the RF power source, the VSWR at the port can be calculated to be approximately 1.5 using a calibrated system. Since the operating frequency of a synchronous loop high-frequency system is generally below 10MHz, the RF power source system cannot be configured with a circulator for isolation protection, resulting in the system operating in a high-reflection state for an extended period. In this state, reflected power continuously flows back to the power module, subjecting it to significant reflected power surges over a long period, making it highly susceptible to damage.

[0033] Meanwhile, the traditional two-way coupling method of half-cavity requires the power source to output 4 RF signals, including 2 forward and 2 reverse signals. Therefore, the matching RF power source needs two reverse splitter chassis and a matching feeder system.

[0034] Figure 2 A schematic top view of a half-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is shown.

[0035] like Figure 2 As shown, this application provides a half-cavity direct-coupled magnetic alloy high-frequency cavity for connection to a radio frequency power source, comprising: a cavity body 1, including two symmetrically arranged half-cavities 2; a vacuum pipe 3, disposed inside the cavity body 1 and connecting the two half-cavities 2; multiple magnetic alloy rings 4, disposed in a single half-cavity 2 and coaxially arranged with the vacuum pipe 3, the multiple magnetic alloy rings 4 being parallel to each other; a coupling device 5, used to electromagnetically couple the multiple magnetic alloy rings 4 located in a single half-cavity 2 to form an overall load unit; and an impedance transformation unit 6, disposed on one side of each half-cavity 2 and electrically connected to the overall load unit, used to transform the impedance of the overall load unit to an impedance matching the characteristic impedance of an external feed line, so as to connect to the radio frequency power source through the external feed line.

[0036] For example, two semi-cavities 2 are symmetrically arranged about the central axis of the cavity body 1, located at both ends of the vacuum pipe 3. Each semi-cavity 2 is used to accommodate the magnetic alloy ring 4 and the coupling device 5.

[0037] For example, the vacuum pipe 3 runs horizontally through the entire cavity body 1, with its two ends extending to the outer ends of the two semi-cavities 2 respectively. The interior of the vacuum pipe 3 is an ultra-high vacuum environment for the passage of ion beams.

[0038] For example, each half-cavity 2 contains four magnetic alloy rings 4, arranged sequentially and parallel to each other along the axial direction of the vacuum pipe 3. Each magnetic alloy ring 4 is circular and coaxially fitted onto the outside of the vacuum pipe 3. The four magnetic alloy rings 4 are arranged parallel to each other along the axial direction, and the series coupling line passes through the inner wall of all the magnetic alloy rings 4 in sequence. Essentially, this utilizes the electromagnetic coupling principle of a transformer: the coupling line acts as the primary winding (single turn) of the transformer, and the magnetic alloy ring 4 acts as a high-permeability magnetic core. Due to the high permeability of the magnetic alloy rings, the magnetic flux generated by the primary current is effectively constrained and enhanced. Its electromagnetic effect is equivalent to the secondary side having a multi-turn winding, thereby coupling the four independent magnetic alloy rings 4 loads into a single load unit.

[0039] Based on the half-cavity direct-coupled magnetic alloy high-frequency cavity of this application embodiment, a coupling device 5 is used to directly couple multiple magnetic alloy rings 4 within the same half-cavity 2 into a single load unit. Only one load exists in the entire half-cavity 2, fundamentally eliminating interference from inter-path coupling to the test. The test state is completely consistent with the actual power-on operating state, and the impedance test value is the true impedance value, with no test error. Because the impedance test is deviation-free, the impedance transformation unit 6, designed according to the test value, can accurately transform the impedance of the entire load unit into an impedance matching the characteristic impedance of the external feeder. This application only requires one reverse distributor chassis and two feeder systems, reducing project costs.

[0040] like Figure 2 As shown, the coupling device 5 includes a coupling line that passes through the inner wall of multiple magnetic alloy rings 4 in sequence, and both ends of the coupling line are connected to the impedance transformation unit 6.

[0041] For example, the coupling wire is made of a conductive material, such as copper, copper alloy, or silver-plated copper wire, to reduce high-frequency losses. The cross-sectional shape of the coupling wire can be circular, rectangular, or flat strip. When a flat strip coupling wire is used, its width direction is parallel to the axis of the magnetic alloy ring 4 to increase the coupling area and improve electromagnetic coupling efficiency.

[0042] For example, when the coupling wire passes through each magnetic alloy ring 4, it remains insulated from the inner wall of each magnetic alloy ring 4. To achieve this, the surface of the coupling wire can be coated with an insulating layer or an insulating sleeve can be provided between the coupling wire and the inner wall of the magnetic alloy ring 4.

[0043] For example, the coupling device 5 also includes coupling strips of different structures, which pass sequentially through the inner walls of multiple magnetic alloy rings 4, and both ends of the coupling strips are electrically connected to the impedance transformation unit 6. The material of the coupling strips is preferably copper, beryllium copper, or silver-plated copper strip, and an insulating coating can be provided on their surface to prevent electrical contact with the inner walls of the magnetic alloy rings 4.

[0044] In the embodiments of this application, the impedance transformation unit 6 includes a single-ended to balanced converter and an impedance transformer; the input terminal of the single-ended to balanced converter is connected to the external feed line, and the output terminal is connected to the input terminal of the impedance transformer, which is used to convert the single-ended radio frequency signal transmitted by the external feed line into a balanced radio frequency signal; the output terminal of the impedance transformer is connected to both ends of the coupling line, and the impedance transformer is used to receive the balanced radio frequency signal and perform impedance transformation on the balanced radio frequency signal, and transform the impedance of the overall load unit into an impedance that matches the characteristic impedance of the external feed line through the balanced radio frequency signal after impedance transformation.

[0045] During operation, the single-ended RF signal output from the RF power source is transmitted to the impedance transformation unit 6 via an external feeder. First, the single-ended to balanced converter receives the single-ended RF signal, and its internal transmission line transformer converts the single-ended signal into two balanced RF signals: a first signal and a second signal. The first and second signals have equal amplitudes and a 180-degree phase difference. Both signals are output to the impedance converter. Next, the impedance converter receives the balanced RF signals and simultaneously performs impedance transformation on both signals. After impedance transformation, the impedance converter outputs the transformed balanced RF signal to both ends of the coupling line. Since the coupling line passes sequentially through the inner walls of multiple magnetic alloy rings 4, the balanced RF signal establishes an alternating current on the coupling line, thereby exciting an alternating magnetic field in the magnetic alloy rings 4. The alternating magnetic field induces a longitudinal accelerating electric field in the vacuum pipe 3, which is used to accelerate the ion beam. Meanwhile, because the impedance transformer transforms the impedance of the entire load unit to match the characteristic impedance of the external feeder, the energy output by the RF power source can be efficiently transferred to the load with minimal reflected power and a voltage standing wave ratio (VSWR) maintained below 1.2. Under the same output power requirements, a lower VSWR means less reflected power, eliminating the need for additional output power to compensate for reflection losses, reducing the actual workload of the power source, and extending its lifespan.

[0046] In the embodiments of this application, the impedance transformation unit 6 further includes an impedance matching circuit, which is connected to the impedance transformer and the external feed line respectively, and is used to further match the impedance after transformation by the impedance transformer to the characteristic impedance of the external feed line.

[0047] Although the impedance after being transformed by the impedance transformer is very close to the characteristic impedance of the external feeder, there is still a certain deviation. The impedance matching circuit is used to further finely match the impedance after being transformed by the impedance transformer to the characteristic impedance of the external feeder.

[0048] For example, an impedance matching circuit can use an L-shaped network consisting of an inductor and a capacitor. The connection method of the inductor and capacitor can be either series inductor-parallel capacitor or parallel capacitor-series inductor, depending on the actual impedance characteristics. By adjusting the values ​​of the inductor and capacitor, the impedance transformed by the impedance converter can be further finely matched to the characteristic impedance of the external feeder.

[0049] For example, the impedance matching circuit can be integrated into the same shielded box as the impedance transformation unit 6, or it can be set independently on the external feeder path.

[0050] Figure 3 A schematic diagram of a semi-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is shown. Figure 4 A schematic cross-sectional view of a half-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application is shown.

[0051] like Figure 3 , Figure 4 As shown, multiple magnetic alloy rings 4 are fixed in the semi-cavity 2 by a support member; the support member includes: multiple fixing plates 7, which are evenly distributed along the circumference of the outer edge of the magnetic alloy rings 4 and perpendicular to the magnetic alloy rings 4, and the two ends of each fixing plate 7 are fixedly connected to the two ends of the semi-cavity 2 respectively; and several connecting plates 8, which are evenly distributed along the circumference of the magnetic alloy rings 4 and parallel to the magnetic alloy rings 4, with one end of the connecting plate 8 fixedly connected to the inner wall of the magnetic alloy rings 4 and the other end fixedly connected to the fixing plate 7.

[0052] For example, there are 6 fixing plates 7, which are evenly distributed at 60-degree intervals on the outer edge of the magnetic alloy ring 4.

[0053] For example, the two ends of the fixing plate 7 are connected to the half cavity 2 by bolts.

[0054] For example, the inner wall of the magnetic alloy ring 4 is provided with a gasket, and the connecting plate 8 is connected to the gasket by bolts.

[0055] Based on the semi-cavity direct coupling magnetic alloy high-frequency cavity of this application embodiment, the magnetic alloy ring 4 is fixed to the fixing plate 7 through the connecting plate 8, thereby achieving the effect of fixing the magnetic alloy ring 4 to the semi-cavity 2.

[0056] In the embodiments of this application, the magnetic alloy ring 4 is a ring-shaped magnetic core made of magnetic alloy strip wound together.

[0057] For example, a thin strip of magnetic alloy with a certain width is tightly wound onto a mandrel or mold to form a ring-shaped magnetic core with a multi-layered structure. After winding, the magnetic alloy ring 4 is shaped to maintain its ring shape and dimensional stability.

[0058] Multiple magnetic alloy rings 4 are arranged sequentially along the axial direction of the vacuum pipe 3, parallel to each other and at equal intervals.

[0059] For example, magnetic alloy strips can be made from any of the following materials: iron-based nanocrystalline alloys, iron-based amorphous alloys, cobalt-based amorphous alloys, etc.

[0060] For example, since magnetic alloy strips are metallic, direct contact between adjacent layers after winding will create eddy current paths, leading to increased high-frequency losses. To reduce eddy current losses, an insulating coating is applied to the surface of the magnetic alloy strip.

[0061] In this embodiment, the voltage standing wave ratio (VSWR) of the magnetic alloy high-frequency cavity is less than 1.2 across the entire frequency band. A low VSWR means that the energy output from the RF power source can be efficiently fed into the cavity, with minimal reflected power, significantly improved power transmission efficiency, and reduced risk of damage to the RF power source from reflected waves.

[0062] In an embodiment of this application, the impedance transformation ratio of the impedance transformation unit 6 is designed as the ratio of the characteristic impedance of the external feeder to the equivalent impedance of the overall load unit.

[0063] Specifically, the equivalent impedance of the overall load unit at the working center frequency of the cavity is Z_load. The impedance transformer is connected between the coupling device 5 and the external feed line, and its impedance transformation ratio is 1:M, where M is a positive integer and M=(Z_feed / Z_load), and Z_feed is the characteristic impedance of the external feed line.

[0064] In the embodiments of this application, the impedance transformation ratio of the impedance transformation unit 6 is 1:9.

[0065] The impedance of a single magnetic alloy ring 4 at the working center frequency of the magnetic alloy high-frequency cavity is 80Ω~130Ω. Four magnetic alloy rings 4 are arranged in the half-cavity 2. After the coupling device 5 couples all four magnetic alloy rings 4, the equivalent impedance Z_load of the overall load unit is approximately 300Ω~460Ω. At this time, the transformation ratio of the impedance transformation unit 6 is 1:9, so as to transform the load impedance of approximately 400Ω to approximately 44Ω. By adding an impedance matching circuit, good matching with a standard 50Ω external feed line can be achieved.

[0066] Figure 5 The diagram schematically illustrates the equivalent circuit of a half-cavity direct-coupled magnetic alloy high-frequency cavity according to an embodiment of this application.

[0067] like Figure 5 As shown, the power source and resistor Rs are the internal resistances of the RF power source and the RF power source, respectively, used to provide the excitation signal. Resistor Rs is the source-end matching impedance (i.e., the characteristic impedance of the external feed line). The power source and resistor Rs on the left and the power source and resistor Rs on the right form a symmetrical excitation source, used to achieve bidirectional excitation and ensure the uniformity of cavity impedance. The transformer on the left is the equivalent electromagnetic coupling of the left half-cavity magnetic alloy ring 4, used to realize impedance transformation and electromagnetic coupling between the power source and the load of the left half-cavity. The parallel resistor Rp and capacitor on the left are the high-frequency equivalent impedance of the single magnetic alloy ring 4, R is the loss resistance of the magnetic alloy (corresponding to high-frequency loss), and the parallel capacitor is the parasitic distributed capacitance of the magnetic alloy ring 4. Capacitor Cg is the series coupling capacitor of the coupling device 5, used to realize the direct electromagnetic coupling between the left and right half-cavities, and at the same time undertakes the functions of impedance matching and bandwidth expansion. The transformer on the right, the parallel resistor Rp on the right, and the capacitor on the right are the equivalent structure of the right half-cavity magnetic alloy ring 4, which is symmetrical with the left half-cavity, forming a complete dual half-cavity load unit.

[0068] Example 1

[0069] This embodiment is a specific implementation of the aforementioned half-cavity direct-coupled magnetic alloy high-frequency cavity.

[0070] This embodiment provides a semi-cavity direct-coupled magnetic alloy high-frequency cavity. The cavity includes a cavity shell and four magnetic alloy rings 4 disposed inside the cavity shell. A coupling line passes sequentially through the inner walls of the four magnetic alloy rings 4, coupling all four magnetic alloy rings 4 together. The input end of the coupling line is connected to the secondary (high impedance end) of an impedance transformation unit 6 with an impedance transformation ratio of 1:9, while the primary end of the impedance transformation unit 6 is connected to a standard 50Ω coaxial feeder connector. The impedance of a single magnetic alloy ring 4 at the design center frequency of 3.5MHz is approximately 100Ω. When the four magnetic alloy rings 4 are fully coupled by the coupling line, the overall load impedance is approximately 400Ω.

[0071] Figure 6 The schematic diagram illustrates the circuit principle of the impedance transformation unit 6 according to an embodiment of this application.

[0072] like Figure 6 As shown, T1 is a single-ended to balanced converter, and T2 is an impedance converter with an impedance transformation ratio of 1:9.

[0073] The single-ended to balanced converter uses a cross-wound dual-winding transformer (windings 1-3 and 4-2 are cross-coupled). The input side is a single-ended structure (INPUT is connected to pin 4, and pin 1 is connected to ground), and the output side is a balanced differential structure (pins 3 and 2 are differential output terminals). It is used to convert a single-ended signal with an impedance of 50Ω from the coaxial feeder into a balanced differential signal with equal amplitude and opposite phase, providing symmetrical excitation for the subsequent impedance converter and eliminating common-mode interference.

[0074] The impedance transformer employs a push-pull dual-transformer cascade structure, comprising two sets of symmetrical transformer windings. The input side is a balanced differential signal input, and the output side is a balanced differential output (output+ / output-). The impedance transformation ratio of this transformer is 1:9. The overall load impedance formed by the four magnetic alloy rings 4 connected in series via a coupling line is approximately 400Ω. The impedance transformer transforms this 400Ω load impedance to approximately 44Ω, a value very close to that of a standard 50Ω feeder system. Good matching can be achieved with simple fine-tuning, thus achieving a voltage standing wave ratio (VSWR) of less than 1.2 across the entire frequency band at a center frequency of 3.5MHz. The input of the impedance transformer is connected to the RF power source via a standard 50Ω coaxial feeder connector. Actual testing showed that, after the RF power source supplied power, calculations based on directional coupler data revealed good consistency between the VSWR across the entire frequency band and the data from the cold-state cavity test.

[0075] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined or combined in various ways without departing from the spirit and teachings of this application. All such combinations or combinations fall within the scope of this application.

[0076] The embodiments of this application have been described above. However, these embodiments are merely illustrative and not intended to limit the scope of this application. Although various embodiments have been described above, this does not mean that the measures in the various embodiments cannot be used advantageously in combination. Without departing from the scope of this application, those skilled in the art can make various substitutions and modifications, all of which should fall within the scope of this application.

Claims

1. A semi-cavity direct-coupled magnetic alloy high-frequency cavity, connected to a radio frequency power source, characterized in that, include: The cavity body (1) includes two symmetrically arranged semi-cavities (2); A vacuum pipe (3) is disposed inside the cavity body (1) and connects the two half-cavities (2); Multiple magnetic alloy rings (4) are disposed in a single half cavity (2) and coaxially arranged with the vacuum pipe (3), and the multiple magnetic alloy rings (4) are parallel to each other; The coupling device (5) is used to electromagnetically couple the plurality of magnetic alloy rings (4) located in a single half cavity (2) to form an integral load unit; Impedance transformation unit (6) is disposed on one side of each of the half-cavities (2) and electrically connected to the overall load unit, for transforming the impedance of the overall load unit into an impedance that matches the characteristic impedance of the external feed line, so as to connect to the radio frequency power source through the external feed line.

2. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The coupling device (5) includes a coupling line that passes through the inner wall of the plurality of magnetic alloy rings (4) in sequence, and the two ends of the coupling line are connected to the impedance transformation unit (6).

3. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 2, characterized in that, The impedance transformation unit (6) includes a single-ended to balanced converter and an impedance converter; The input terminal of the single-ended to balanced converter is connected to the external feed line, and the output terminal is connected to the input terminal of the impedance converter, which is used to convert the single-ended radio frequency signal transmitted by the external feed line into a balanced radio frequency signal. The output terminals of the impedance transformer are connected to both ends of the coupling line. The impedance transformer is used to receive the balanced radio frequency signal and perform impedance transformation on the balanced radio frequency signal, and transform the impedance of the overall load unit into an impedance that matches the characteristic impedance of the external feed line through the impedance-transformed balanced radio frequency signal.

4. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 3, characterized in that, The impedance transformation unit (6) further includes an impedance matching circuit, which is connected to the impedance transformer and the external feed line respectively, and is used to further match the impedance after transformation by the impedance transformer to the characteristic impedance of the external feed line.

5. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The plurality of magnetic alloy rings (4) are fixed in the semi-cavity (2) by a support member; The support member includes: Multiple fixing plates (7) are evenly distributed around the outer edge of the magnetic alloy ring (4) and perpendicular to the magnetic alloy ring (4). The two ends of each fixing plate (7) are fixedly connected to the two ends of the half cavity (2). Several connecting plates (8) are evenly distributed along the circumference of the magnetic alloy ring (4) and parallel to the magnetic alloy ring (4). One end of the connecting plate (8) is fixedly connected to the inner wall of the magnetic alloy ring (4), and the other end is fixedly connected to the fixing plate.

6. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The magnetic alloy ring (4) is a ring-shaped magnetic core made of magnetic alloy strip wound together.

7. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The voltage standing wave ratio (VSWR) of the magnetic alloy high-frequency cavity is less than 1.2 across the entire frequency band.

8. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The impedance transformation ratio of the impedance transformation unit (6) is designed as follows: The ratio of the characteristic impedance of the external feeder to the equivalent impedance of the overall load unit.

9. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The impedance transformation ratio of the impedance transformation unit (6) is 1:

9.

10. The semi-cavity direct-coupled magnetic alloy high-frequency cavity according to claim 1, characterized in that, The impedance of a single magnetic alloy ring (4) at the working center frequency of the magnetic alloy high-frequency cavity is 80Ω~130Ω.

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