Accelerator slow extraction radio frequency kick device

Abstract

The application belongs to the technical field of strong current ion synchrotron, and relates to an accelerator slow extraction radio frequency excitation device, which comprises a digital programmable signal source, a microwave bridge, a power amplifier, an exciter and a high-power attenuator, the output end of the digital programmable signal source is connected with the input end of the microwave bridge, the output end of the microwave bridge is connected with the input end of the power amplifier, the output end of the power amplifier is connected with the input end of the exciter, the exciter is used for feeding radio frequency power to the pole plate of the exciter, the output end of the exciter is connected with the input end of the high-power attenuator, and the output end of the high-power attenuator is connected with the input end of the digital programmable signal source. The device has the functions of monitoring the output power of the power amplifier and whether the excitation pole plate works normally in real time, can realize high efficiency of slow extraction excitation (high transverse shunt impedance), and takes into account the working bandwidth.

Description

Technical Field

[0001] This invention relates to a slow-extraction radio frequency excitation device for an accelerator, belonging to the technical field of high-current ion ring accelerators. Background Technology

[0002] Synchrotron slow extraction systems can provide quasi-continuous beams on the order of seconds, applicable to materials science, biological irradiation research, proton and heavy ion therapy for cancer, and nuclear physics experiments. Heavy ion therapy is an effective radiotherapy method for cancer due to its deep dose distribution, low lateral scattering, high relative biological effect, and low oxygen enrichment ratio. Commonly used deep heavy ion therapy beam energies for cancer treatment range from 120 mevav / u to 400 mevav / u (heavy ions).

[0003] Radio frequency (RF) excitation is a common method for slow beam extraction in synchrotrons. It generates an RF electric field that kicks the beam, gradually increasing its emittance and leading to beam extraction. This method requires a first RF excitation device with two horizontally spaced electrodes. RF power is applied to these electrodes, creating a transverse RF electric field between them, which kicks the beam, increasing its emittance and leading to extraction. Existing slow beam extraction RF excitation devices for synchrotrons, such as CN209676568U, disclose an RF excitation device comprising: a vacuum chamber and four sets of electrode assemblies fixed within the vacuum chamber; two sets of electrode assemblies are spaced horizontally to generate a horizontal RF excitation electric field for beam extraction and measurement of either the horizontal or vertical operating point; the other two sets are spaced vertically to generate a vertical RF excitation electric field for measurement of the vertical operating point, thus integrating beam extraction, horizontal operating point measurement, and vertical operating point measurement. The patent discloses functions that enable slow lead-out and operating point measurement.

[0004] However, this slow extraction excitation device has drawbacks such as high beam coupling impedance, which cannot meet the requirements of high-current ion accelerators, lack of real-time monitoring of whether the applied power to the excitation plates is normal, and inability to achieve high efficiency of slow extraction excitation while also taking into account the operating bandwidth. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide an accelerator slow-extraction radio frequency excitation device, which has the function of real-time monitoring of the power amplifier output power and whether the excitation plate is working properly, and can achieve high efficiency of slow-extraction excitation (high lateral shunt impedance) while taking into account the operating bandwidth.

[0006] To achieve the above objectives, the present invention proposes the following technical solution: an accelerator slow-extraction radio frequency excitation device, comprising: a digital programmable signal source, a microwave bridge, a power amplifier, an exciter, and a high-power attenuator. The output terminal of the digital programmable signal source is connected to the input terminal of the microwave bridge, the output terminal of the microwave bridge is connected to the input terminal of the power amplifier, the output terminal of the power amplifier is connected to the input terminal of the exciter for feeding radio frequency power to the plates of the exciter, the output terminal of the exciter is connected to the input terminal of the high-power attenuator, and the output terminal of the high-power attenuator is connected to the input terminal of the digital programmable signal source.

[0007] Furthermore, there are at least two exciters, and multiple exciters are connected in series or in parallel. When the exciters are connected in series, each exciter is connected through a high-power coaxial radio frequency cable.

[0008] Furthermore, when the exciters are connected in series, the microwave bridge includes a 0° microwave circuit and a 180° microwave circuit. Each of the 0° microwave circuit and the 180° microwave circuit is connected to a power amplifier. The exciter's plates include an upper plate and a lower plate. The power amplifier connected to the 0° microwave circuit is connected to the upper plate, and the power amplifier connected to the 180° microwave circuit is connected to the lower plate.

[0009] Furthermore, the power amplifier is connected to the upper or lower electrode plate via an upstream ultra-high vacuum feedthrough, and the upper and lower electrode plates are respectively connected to a high-power attenuator via a downstream ultra-high vacuum feedthrough.

[0010] Furthermore, when the exciters are connected in parallel, an in-phase power divider is set between the digital programmable signal source and the microwave bridge. The output of the digital programmable signal source is connected to the input of the in-phase power divider, and the output of the in-phase power divider is connected to the input of the microwave bridge. There are multiple microwave bridges, and their number is the same as the number of exciters.

[0011] Furthermore, the microwave bridge includes a 0° microwave circuit and a 180° microwave circuit, each of which is connected to a power amplifier. The exciter's plates include an upper plate and a lower plate. The power amplifier connected to the 0° microwave circuit is connected to the upper plate, and the power amplifier connected to the 180° microwave circuit is connected to the lower plate.

[0012] Furthermore, the isolation of both the in-phase power divider and the 180° microwave bridge is greater than 25dB.

[0013] Furthermore, the power amplifier is connected to the upper or lower electrode plate via an upstream ultra-high vacuum feedthrough, and the upper and lower electrode plates are respectively connected to a high-power attenuator via a downstream ultra-high vacuum feedthrough.

[0014] Furthermore, the digital programmable signal source includes a direct digital frequency synthesizer, a digital-to-analog converter, and an analog-to-digital converter. The direct digital frequency synthesizer generates a radio frequency power signal. The digital-to-analog converter is located at the output end of the digital programmable signal source and is used to convert the radio frequency power signal into an analog signal. The analog-to-digital converter is located at the input end of the digital programmable signal source and is used to convert the input analog signal into a digital signal and then feed it back to the direct digital frequency synthesizer.

[0015] Furthermore, the power amplifier is an RF microwave power amplifier with a harmonic suppression degree greater than 20dBc, and the power capacity of the high-power attenuator is more than 1.5 times that of the power amplifier.

[0016] Due to the adoption of the above technical solutions, the present invention has the following advantages: the present invention has the advantages of balancing strong and weak beam currents, low beam coupling impedance, real-time monitoring of power amplifier output power and whether the excitation plate is working properly, and can achieve high efficiency of slow extraction excitation while taking into account the working bandwidth. It can be widely used in the field of slow beam extraction in high-current ion accelerators or medical heavy ion beam accelerators. Attached Figure Description

[0017] Figure 1 This is an accelerator slow-extraction radio frequency excitation device in one embodiment of the present invention;

[0018] Figure 2 This is an accelerator slow-extraction radio frequency excitation device in another embodiment of the present invention;

[0019] Figure 3 This is a diagram showing the calculation results of the transverse shunt impedance of the exciter with different electrode plate lengths in one embodiment of the present invention.

[0020] Figure label:

[0021] 1-Digital programmable signal source; 2-In-phase power divider; 3-Microwave bridge; 4-Power amplifier; 5-Exciter; 51-Electrode plate; 511-Upper electrode plate; 512-Lower electrode plate; 52-Vacuum pipe; 53-Vacuum flange; 54-Insulating support; 55-Ultra-high vacuum feedthrough; 551-Upstream ultra-high vacuum feedthrough; 552-Downstream ultra-high vacuum feedthrough; 6-High-power attenuator; 7-High-power coaxial RF cable. Detailed Implementation

[0022] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention is described in detail through specific embodiments. However, it should be understood that the specific embodiments are provided only for a better understanding of the present invention and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the terminology used is for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0023] To address the shortcomings of existing slow-extraction excitation devices, such as high beam coupling impedance (unable to meet the requirements of high-current ion accelerators), lack of real-time monitoring of the applied power on the excitation plates, and inability to achieve both high efficiency and sufficient operating bandwidth, a new accelerator slow-extraction radio frequency excitation device is proposed. This device includes: a digitally programmable signal source 1, a microwave bridge 3, a power amplifier 4, an exciter 5, and a high-power attenuator 6. The output of the digitally programmable signal source 1 is connected to the input of the microwave bridge 3, the output of the microwave bridge 3 is connected to the input of the power amplifier 4, the output of the power amplifier 4 is connected to the input of the exciter 5, and is used to feed radio frequency power to the plates 51 of the exciter 5. The output of the exciter 5 is connected to the input of the high-power attenuator 6, and the output of the high-power attenuator 6 is connected to the input of the digitally programmable signal source 1. This invention offers advantages such as balancing strong and weak beam currents, low beam coupling impedance, real-time monitoring of power amplifier output power and exciter electrode 51's normal operation, and high efficiency of slow excitation while maintaining sufficient operating bandwidth. It can be widely applied in the field of slow beam extraction in high-current ion accelerators or medical heavy ion beam accelerators. The following detailed description of the invention, in conjunction with the accompanying drawings, uses embodiments to illustrate the solution.

[0024] Example 1

[0025] This embodiment discloses an accelerator slow-extraction radio frequency excitation device, such as... Figure 1 As shown, the system includes: a digitally programmable signal source 1, an in-phase power divider 2, a microwave bridge 3, a power amplifier 4, an exciter 5, and a high-power attenuator 6. The output of the digitally programmable signal source 1 is connected to the input of the in-phase power divider 2. The digitally programmable signal source 1 is connected to the input of the microwave bridge 3 through the in-phase power divider 2. The output of the microwave bridge 3 is connected to the input of the power amplifier 4. The output of the power amplifier 4 is connected to the input of the exciter 5, which is used to feed radio frequency power to the plates 51 of the exciter 5. The output of the exciter 5 is connected to the input of the high-power attenuator 6. The output of the high-power attenuator 6 is connected to the input of the digitally programmable signal source 1, achieving slow beam extraction with low beam impedance and wide bandwidth.

[0026] The digital programmable signal source 1 includes a direct digital frequency synthesizer, a digital-to-analog converter, and an analog-to-digital converter. The direct digital frequency synthesizer generates a radio frequency power signal. The digital-to-analog converter is located at the output end of the digital programmable signal source 1 and is used to convert the radio frequency power signal into an analog signal. The analog-to-digital converter is located at the input end of the digital programmable signal source 1 and is used to convert the input analog signal into a digital signal and then feed it back to the direct digital frequency synthesizer.

[0027] There are at least two exciters 5; in this embodiment, there are two exciters 5 connected in parallel. The output terminal of the in-phase power divider 2 is connected to the input terminal of the microwave bridge 3, and there are two microwave bridges 3. The microwave bridge 3 includes a 0° microwave circuit and a 180° microwave circuit, and each of the 0° microwave circuit and the 180° microwave circuit is connected to a power amplifier 4.

[0028] Each actuator 5 includes an electrode plate 51, a vacuum pipe 52, a vacuum flange 53, an insulating support 54, and an ultra-high vacuum feedthrough 55. The electrode plate 51 includes an upper electrode plate 511 and a lower electrode plate 512, which are fixed above and below the vacuum pipe 52, respectively. The vacuum flange 53 is fixed at both ends of the vacuum pipe 52. The insulating support 54 and the ultra-high vacuum feedthrough 55 are both disposed on the outer wall of the vacuum pipe 52. The insulating support 54 is used to fix the upper electrode plate 511 and the lower electrode plate 512. The ultra-high vacuum feedthrough 55 includes a downstream ultra-high vacuum feedthrough 552 and an upstream ultra-high vacuum feedthrough 551. There are two downstream ultra-high vacuum feedthroughs 552, which are connected to the upper electrode plate 511 and the lower electrode plate 512, respectively. There are also two upstream ultra-high vacuum feedthroughs 551, which are also connected to the upper electrode plate 511 and the lower electrode plate 512, respectively. Power amplifier 4, connected to the 0° microwave circuit, is connected to the upper electrode 511, and power amplifier 4, connected to the 180° microwave circuit, is connected to the lower electrode 512. The isolation between the in-phase power divider 2 and the 180° microwave circuit is greater than 25dB. Power amplifier 4 is connected to either the upper electrode 511 or the lower electrode 512 via an upstream ultra-high vacuum feedthrough 551 for feeding in RF power. The upper electrode 511 and the lower electrode 512 are respectively connected to a high-power attenuator 6 via a downstream ultra-high vacuum feedthrough 552 for extracting RF power. In this embodiment, the characteristic impedance of the exciter 5 is 50 ohms, and the angle of the electrode 51 of the exciter 5 is 90°.

[0029] Power amplifier 4 is an RF microwave power amplifier with a harmonic suppression degree greater than 20dBc, and the power capacity of high power attenuator 6 is more than 1.5 times that of power amplifier 4.

[0030] Example 2

[0031] When there is ample space for beamline installation, and the extracted beam current energy is high and a large kick-out is required, two or more exciters 5 can be connected in parallel to reduce the output power of each power amplifier 44, thereby reducing the system cost. Therefore, based on the same inventive concept, this embodiment discloses an accelerator slow-extraction radio frequency excitation device, such as... Figure 2 As shown, it includes:

[0032] The circuit consists of a digital programmable signal source 1, a microwave bridge 3, a power amplifier 4, an exciter 5, and a high-power attenuator 6. The output of the digital programmable signal source 1 is connected to the input of the microwave bridge 3. The output of the microwave bridge 3 is connected to the input of the power amplifier 4. The output of the power amplifier 4 is connected to the input of the exciter 5 to feed radio frequency power to the plates 51 of the exciter 5. The output of the exciter 5 is connected to the input of the high-power attenuator 6. The output of the high-power attenuator 6 is connected to the input of the digital programmable signal source 1. This ultimately achieves high excitation efficiency (high lateral shunt impedance) and slow beam extraction. The output result is as follows: Figure 3 As shown.

[0033] The digital programmable signal source 1 includes a direct digital frequency synthesizer (DDS), a digital-to-analog converter (DAC), and an analog-to-digital converter (ADC). The direct digital frequency synthesizer generates an radio frequency power signal. The DAC is located at the output of the digital programmable signal source 1 and is used to convert the radio frequency power signal into an analog signal. The ADC is located at the input of the digital programmable signal source 1 and is used to convert the input analog signal into a digital signal and then feed it back to the direct digital frequency synthesizer.

[0034] There are at least two exciters 5. In this embodiment, there are two exciters 5 connected in series. The two exciters 5 are connected by a high-power coaxial radio frequency cable 7. The microwave bridge 3 includes a 0° microwave circuit and a 180° microwave circuit. Each of the 0° microwave circuit and the 180° microwave circuit is connected to a power amplifier 4. The electrode plates 51 of the exciters 5 include an upper electrode plate 511 and a lower electrode plate 512. The power amplifier 4 connected to the 0° microwave circuit is connected to the upper electrode plate 511, and the power amplifier 4 connected to the 180° microwave circuit is connected to the lower electrode plate 512.

[0035] Each actuator 5 includes an electrode plate 51, a vacuum pipe 52, a vacuum flange 53, an insulating support 54, and an ultra-high vacuum feedthrough 55. The electrode plate 51 includes an upper electrode plate 511 and a lower electrode plate 512, which are fixed above and below the vacuum pipe 52, respectively. The vacuum flange 53 is fixed at both ends of the vacuum pipe 52. The insulating support 54 and the ultra-high vacuum feedthrough 55 are both disposed on the outer wall of the vacuum pipe 52. The insulating support 54 is used to fix the upper electrode plate 511 and the lower electrode plate 512. The ultra-high vacuum feedthrough 55 includes a downstream ultra-high vacuum feedthrough 552 and an upstream ultra-high vacuum feedthrough 551. There are two downstream ultra-high vacuum feedthroughs 552, which are connected to the upper electrode plate 511 and the lower electrode plate 512, respectively. There are also two upstream ultra-high vacuum feedthroughs 551, which are also connected to the upper electrode plate 511 and the lower electrode plate 512, respectively. Power amplifier 4, connected to the 0° microwave circuit, is connected to the upper electrode 511, and power amplifier 4, connected to the 180° microwave circuit, is connected to the lower electrode 512. Power amplifier 4 is connected to the upper electrode 511 or the lower electrode 512 via an upstream ultra-high vacuum feedthrough 551 for feeding in radio frequency power. The upper electrode 511 and the lower electrode 512 are respectively connected to a high-power attenuator 6 via a downstream ultra-high vacuum feedthrough 552 for extracting radio frequency power. In this embodiment, the characteristic impedance of exciter 5 is 50 ohms, and the angle of the electrode 51 of exciter 5 is 90°.

[0036] Power amplifier 4 is an RF microwave power amplifier with a harmonic suppression degree greater than 20dBc, and the power capacity of high power attenuator 6 is more than 1.5 times that of power amplifier 4.

[0037] When the installation space for the exciter 5 is limited, such as in heavy ion therapy devices which are typically very compact and have limited installation space, one of the exciters 5 can also be used to achieve slow beam extraction.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific embodiments of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention. The above content is only a specific embodiment of this application, but the protection scope of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be covered within the protection scope of this application. Therefore, the protection scope of this application should be determined by the protection scope of the claims.

Claims

1. An accelerator slow-extraction radio frequency excitation device, characterized in that, include: Digital programmable signal source, microwave bridge, power amplifier, exciter and high power attenuator, The output terminal of the digital programmable signal source is connected to the input terminal of the microwave bridge, the output terminal of the microwave bridge is connected to the input terminal of the power amplifier, the output terminal of the power amplifier is connected to the input terminal of the exciter, and is used to feed radio frequency power to the plates of the exciter. The output terminal of the exciter is connected to the input terminal of the high-power attenuator, and the output terminal of the high-power attenuator is connected to the input terminal of the digital programmable signal source.

2. The accelerator slow-extraction radio frequency excitation device as described in claim 1, characterized in that, The exciter is at least two, and the multiple exciters are connected in series or in parallel. When the exciters are connected in series, each exciter is connected by a high-power coaxial radio frequency cable.

3. The accelerator slow-extraction radio frequency excitation device as described in claim 2, characterized in that, When the exciters are connected in series, the microwave bridge includes a 0° microwave circuit and a 180° microwave circuit. Each of the 0° microwave circuit and the 180° microwave circuit is connected to a power amplifier. The electrodes of the exciter include an upper electrode and a lower electrode. The power amplifier connected to the 0° microwave circuit is connected to the upper electrode, and the power amplifier connected to the 180° microwave circuit is connected to the lower electrode.

4. The accelerator slow-extraction radio frequency excitation device as described in claim 3, characterized in that, The power amplifier is connected to the upper or lower electrode plate via an upstream ultra-high vacuum feedthrough, and the upper and lower electrode plates are respectively connected to a high-power attenuator via a downstream ultra-high vacuum feedthrough.

5. The accelerator slow-extraction radio frequency excitation device as described in claim 2, characterized in that, When the exciters are connected in parallel, an in-phase power divider is provided between the digital programmable signal source and the microwave bridge. The output terminal of the digital programmable signal source is connected to the input terminal of the in-phase power divider, and the output terminal of the in-phase power divider is connected to the input terminal of the microwave bridge. There are multiple microwave bridges, and their number is the same as the number of exciters.

6. The accelerator slow-extraction radio frequency excitation device as described in claim 5, characterized in that, The microwave bridge includes a 0° microwave circuit and a 180° microwave circuit. Each of the 0° microwave circuit and the 180° microwave circuit is connected to a power amplifier. The exciter's plates include an upper plate and a lower plate. The power amplifier connected to the 0° microwave circuit is connected to the upper plate, and the power amplifier connected to the 180° microwave circuit is connected to the lower plate.

7. The accelerator slow-extraction radio frequency excitation device as described in claim 6, characterized in that, The isolation of the in-phase power divider and the 180° microwave bridge is greater than 25dB.

8. The accelerator slow-extraction radio frequency excitation device as described in claim 6, characterized in that, The power amplifier is connected to the upper or lower electrode plate via an upstream ultra-high vacuum feedthrough, and the upper and lower electrode plates are respectively connected to a high-power attenuator via a downstream ultra-high vacuum feedthrough.

9. The accelerator slow-extraction radio frequency excitation device according to any one of claims 1-8, characterized in that, The digital programmable signal source includes a direct digital frequency synthesizer, a digital-to-analog converter, and an analog-to-digital converter. The direct digital frequency synthesizer generates a radio frequency power signal. The digital-to-analog converter is located at the output end of the digital programmable signal source and is used to convert the radio frequency power signal into an analog signal. The analog-to-digital converter is located at the input end of the digital programmable signal source and is used to convert the input analog signal into a digital signal and then feed it back to the direct digital frequency synthesizer.

10. The accelerator slow-extraction radio frequency excitation device according to any one of claims 1-7, characterized in that, The power amplifier is a radio frequency microwave power amplifier with a harmonic suppression degree greater than 20dBc, and the power capacity of the high-power attenuator is more than 1.5 times that of the power amplifier.

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