CN109893777B - Phase detector and proton beam phase stabilization device including the same - Google Patents

Abstract

The invention relates to the technical field of cyclotrons, and discloses a phase detector, a proton beam phase stabilization device including the phase detector, and a control method, including a phase detector, a frequency multiplier, and a phase detector for picking up beam phase information. A phase detector connected with the detector and the frequency multiplier, an analog/digital converter connected with the phase detector, and a digital signal processing unit connected with the analog/digital converter. The resonant cavity of the phase detector picks up the beam phase information and the frequency tripled signal of the resonant cavity for phase detection. The phase-detected signal is processed by the digital signal processing unit to control and adjust the power supply of the main magnet, so as to realize the beam phase information and high-frequency phase. The fast and intelligent matching of information provides technical guarantee for the beam stabilization system in proton therapy equipment.

Description

Phase detector and proton beam phase stabilization device including the same

technical field

The present invention relates to the technical field of cyclotrons, in particular to a phase detector and a proton beam phase stabilization device including the phase detector.

Background technique

In proton therapy, in order to achieve the precise transmission of the therapeutic dose, in addition to the high requirements for the diagnosis accuracy of the patient's tumor and the subsequent beam transmission system, the quality and stability of the proton beam are also very important at the source of the beam, that is, the accelerator end. high demands.

Usually, in the stage of accelerator design, construction and debugging, the parameters such as the envelope, dispersion, and current intensity of the beam are optimized, which can fully meet the requirements of proton therapy for beam quality. However, since the proton therapy system needs to operate for a long time, during the long-term operation, the heating of accelerator components (such as high-frequency cavity, etc.) and the interference of external signals will adversely affect the beam stability of the accelerator, resulting in parameters such as beam current intensity and dispersion. changes, which are detrimental to the precise dose delivery required for proton therapy.

In order to solve the above problems, in the laboratory environment, professional operators and accelerator experts can intervene manually to readjust the accelerator parameters and optimize the beam parameters. However, for the future large-scale operation of proton therapy equipment in hospitals, the It is unrealistic, so it is necessary to develop an automatic measurement and feedback adjustment system for beam stability on the basis of fully studying the factors affecting beam stability.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a phase detector, which adopts a cavity structure and can be installed on the beam line, and the beam passes through the middle of the cavity, which can better induce resonance and make the signal more obvious.

The above-mentioned purpose of the present invention is achieved through the following technical solutions:

The phase detector includes a cylindrical cavity with a closed end face and a hollow inner rod located at the inner axis of the cavity. One end of the inner rod is open and the other end is closed. The interior is a resonant cavity, and the inner rod is open. The end is provided with an adjusting ring, and the end surface of the cavity cylinder corresponding to the open end of the inner rod is provided with a first opening which leads into the resonance cavity of the inner rod.

By using the above technical solution, it adopts a cavity structure to form a non-blocking phase detector, which can be installed on the beam line, the beam passes through the middle of the cavity, the open end of the inner rod forms an open end, and the closed end A short-circuit end is formed, and the beam phase information is picked up at the short-circuit end, and the resonance can be better caused, and the signal is more obvious.

In some embodiments, the end faces of the two ends of the cavity cylinder are respectively provided with cover plates in sealing connection with the cavity cylinder.

By adopting the above technical solution, the end face and the peripheral face of the cavity cylinder adopt a split structure, which facilitates the installation and maintenance of the inner rod.

In some embodiments, the inner rod is a hollow tube body with two open ends, the two ends of which are connected to the cover plate, and the cover plate corresponding to the closed end of the inner rod is provided with a resonant cavity leading to the inner rod The second opening of the cover plate is provided with a blind cover corresponding to the second opening, the inner rod is sealed with the cover plates at both ends, and the blind cover is sealed with the cover plates.

By adopting the above technical scheme, the resonant cavity is formed into a sealed ring shape, so as to realize vacuum extraction, avoid external factors from interfering with the beam current, and ensure the accuracy of picking up the beam current phase information.

In some embodiments, a vacuum quick-release flange is connected to the first opening on the outside of the cavity.

By adopting the above technical solution, the fast installation of the phase detector is realized, and the tightness of the beam inlet is ensured at the same time.

In some embodiments, the axial length of the cavity barrel is equal to a quarter wavelength.

By adopting the above technical scheme, the length of the cavity cylinder is controlled, which facilitates the installation of the phase detector on the beam line and avoids the interference from the fundamental frequency of the high-frequency cavity of the accelerator.

The second object of the present invention is to provide the above-mentioned proton beam phase stabilization device including the phase detector, which can automatically measure the beam phase information and perform feedback adjustment.

The above object of the present invention is achieved through the following technical solutions: a phase detector, installed on the cyclotron beam transport line, has a resonant cavity, and when the beam passes through the resonant cavity, a magnetic field is excited in the resonant cavity, and the phase The detector picks up the beam phase information;

Also includes:

A frequency multiplier, which converts the high-frequency phase information of the resonant cavity into a triple frequency signal output;

The phase detector is connected with the phase detector and the frequency multiplier to determine the phase difference relationship between the beam phase information and the high-frequency phase information;

The analog/digital converter is connected with the phase detector, and converts the phase difference information output by the phase detector into a digital signal;

The digital signal processing unit is connected with the analog/digital converter and the main magnet power supply of the cyclotron. The digital signal processing unit processes the digital signal transmitted by the analog/digital converter and controls and adjusts the main magnet power supply to tune the magnetic field strength of the cyclotron.

By adopting the above technical scheme, the resonant cavity of the phase detector picks up the beam phase information and the frequency tripled signal of the resonant cavity for phase detection, and the phase-detected signal is processed by the digital signal processing unit to control and adjust the power supply of the main magnet, so as to realize the beam current The fast and intelligent matching of phase information and high-frequency phase information provides technical guarantee for the beam stabilization system in proton therapy equipment.

In some embodiments, filters are connected between the phase detector and the phase detector, and between the frequency multiplier and the phase detector.

By adopting the above technical solution, the filter can effectively filter out the interference signal of the picked-up beam phase information, so as to ensure effective information and improve the picked-up quality.

In some embodiments, an amplifier is connected between the filter and the phase detector.

Since the strength of the phase signal is relatively weak, by adopting the above technical solution, the phase signal can be amplified, which is convenient for later comparison and comparison.

To sum up, the beneficial technical effects of the present invention are:

1. By setting the phase detector as a cavity structure, it can be installed on the beam line, and the beam passes through the middle of the cavity, which can better induce resonance and the signal is more obvious;

2. By using the resonant cavity of the phase detector to pick up the beam phase information and the frequency tripled signal of the resonant cavity for phase detection, the signal after phase detection is processed by the digital signal processing unit to control and adjust the main magnet power supply to realize the beam phase information. Fast and intelligent matching with high-frequency phase information provides technical guarantee for the beam stabilization system in proton therapy equipment.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the phase detector provided by the present invention.

FIG. 2 is an exploded view of the phase detector shown in FIG. 1 .

FIG. 3 is a structural block diagram of the proton beam phase stabilization device provided by the present invention.

In the figure: 1, phase detector; 10, resonant cavity; 2, frequency multiplier; 3, phase detector; 4, analog/digital converter; 5, digital signal processing unit; 6, main magnet power supply; 7, filter device; 8, amplifier; 101, cavity cylinder; 102, inner rod; 1011, cover plate; 1021, adjusting ring; 1012, first opening; 1014, blind cover; 121, vacuum quick release flange.

Detailed ways

The present invention will be further described in detail below with reference to the accompanying drawings.

The present invention discloses a phase detector, as shown in FIG. 1 and FIG. 2 , comprising a cylindrical cavity 101 and a hollow inner rod 102 penetrated at the axial center of the cavity 101 , and the inner rod 102 is a hollow tube with both ends open. The inner part is the resonant cavity 10, the two end faces of the cavity cylinder 101 are respectively provided with cover plates 1011, the two ends of the inner rod 102 are sealed with the cover plates 1011, and the cover plates 1011 at both ends are respectively provided with holes leading to the resonant cavity 10 of the inner rod 102. The first opening 1012 and the second opening (not shown in the figure), the cover plate 1011 with the second opening corresponding to the second opening is covered with a blind cover 1014. The blind cover 1014 is sealed with the cover plate 1011 , so that the end of the inner rod 102 corresponding to the first opening 1012 is open and the other end is closed. As shown in FIG. 2 , an adjusting ring 1021 is provided at the open end of the inner rod 102 , and a vacuum quick-release flange 121 is connected to the first opening 1012 at the outer side of the cavity cylinder 101 . The above structure forms a non-blocking phase detector, the open end of the inner rod 102 forms an open end, and the closed end forms a short circuit end. The end of the quick-release flange 121 is injected into the inner rod 102, and the magnetic field is excited when the beam passes through the resonant cavity, and the beam phase information is picked up at the short-circuit end, so as to realize the pickup of the beam phase information. The device adopts a cavity structure, which can be installed on the beam line, and the beam passes through the middle of the cavity, so as to better induce resonance and make the signal more obvious.

In order to control the length of the phase detector, and to avoid the interference from the fundamental frequency of the accelerator's high-frequency cavity, the axial length of the phase detector 1 is equal to a quarter wavelength, that is, its length is about 0.35m. At the same time, the beam current The sampling frequency of the phase information is the third harmonic frequency, the high frequency of the cyclotron is 71.5MHz, and the third harmonic frequency is 214.5MHz.

As shown in FIG. 3 , the present invention also discloses a proton beam phase stabilization device including the phase detector. The phase detector 1 is installed on the beam transport line of the cyclotron and has a resonant cavity 10 . When the beam passes through the resonant cavity 10 The magnetic field is excited in the resonant cavity 10, and the phase detector 1 picks up the beam phase information

Frequency multiplier 2, outputs the high-frequency phase information of the cavity of the resonant cavity 10 into a triple frequency signal;

Also includes:

The phase detector 3 is connected with the phase detector 1 and the frequency multiplier 2 to determine the phase difference relationship between the beam phase information and the high-frequency phase information;

Filter 7, located between the high-frequency phase detector 1 and the phase detector 3, and between the frequency multiplier 2 and the phase detector 3, is used to effectively filter out the interference signal that picks up the beam phase information to ensure effective information to improve picking quality;

Amplifier 8, located between filter 7 and phase detector 3, to amplify the phase signal, which is convenient for later comparison;

The analog/digital converter 4 is connected with the phase detector 3 to convert the phase difference information output by the phase detector 3 into a digital signal;

The digital signal processing unit 5 is connected with the analog/digital converter 4 and the main magnet power supply 6 of the cyclotron. The digital signal processing unit 5 processes the digital signal transmitted by the analog/digital converter 4 and controls and adjusts the main magnet power supply 6 to tune The magnetic field strength of the cyclotron.

When the beam passes through the resonant cavity 10 of the phase detector 1, a magnetic field is excited, and the high-frequency phase detector 1 picks up the beam phase information, and uses the beam phase information as the input of the feedback loop that controls the magnetic field strength, sampling the beam phase information The frequency selects its third harmonic frequency, the high frequency frequency of the cyclotron is 71.5MHz, and its third harmonic frequency is 214.5MHz; the frequency multiplier 2 outputs the high frequency phase information of the cavity 10 into a triple frequency signal, that is, in In this embodiment of the present invention, the high-frequency phase information frequency of the cavity of the resonant cavity 10 is 71.5MHz, and the output frequency of the triple frequency signal is 214.5MHz; the interference of the beam phase information and the high-frequency phase information through the filter 7 respectively The signal is effectively filtered, and the beam phase information is amplified by the amplifier 8 in two stages, and then is amplified and detected by limiting the zero-crossing; the beam phase information after filtering and amplifying processing and the filtered high-frequency phase information are sent. To the phase detector 3 composed of the double-balanced mixer, the output signal is the I component and the Q component related to the phase difference between the two; the phase difference information after the phase detection is transmitted to the analog-to-digital converter 4. It is sent to the digital signal processing unit 5, and the digital signal processing unit 5 controls and adjusts the main magnet power source 6 of the cyclotron according to the phase detection result to tune the magnetic field strength of the cyclotron, thereby realizing the fast and intelligent matching of the beam phase and the high-frequency phase.

In order to reduce the influence of external noise on the system, the phase detector provided by the present invention and all circuit boards of the proton beam phase stabilization device including the phase detector are placed in a VME chassis with a height of 3U, which can provide good At the same time, a high-precision linear power supply is used for power supply to reduce the adverse effects of power supply ripple on sensitivity. In addition, an inductance is added to the power supply circuit of high-frequency devices to prevent possible damage to other parts. interference.

The embodiments of this specific embodiment are all preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Therefore: all equivalent changes made according to the structure, shape and principle of the present invention should be covered in within the protection scope of the present invention.

Claims (4)

1. A phase detector, characterized in that it comprises a cylindrical cavity (101) and a hollow inner rod (102) passing through the axial position of the cavity (101), and the inner rod (102) is open at both ends The hollow tube body has a resonant cavity (10) inside, cover plates (1011) are respectively provided on both ends of the cavity cylinder (101), and both ends of the inner rod (102) are connected to the cover plates (1011). Sealed connection, the cover plates (1011) at both ends are respectively provided with a first opening (1012) and a second opening that are passed into the resonant cavity (10) of the inner rod (102), and a cover plate with a second opening is opened A blind cover (1014) is provided on the cover corresponding to the second opening on the (1011), and the blind cover (1014) is sealedly connected with the cover plate (1011), so that the inner rod (102) corresponds to the first One end of the opening (1012) is open and the other end is closed. 2 . The phase detector according to claim 1 , wherein the first opening ( 1012 ) is located outside the cavity ( 101 ) and is connected with a vacuum quick-release flange ( 121 ). 3 . 3. The phase detector according to claim 1, wherein the axial length of the cavity barrel (101) is equal to a quarter wavelength. 4. The proton beam phase stabilization device comprising the phase detector according to any one of claims 1 to 3, wherein the phase detector (1) is installed on the cyclotron beam transport line and has a resonant cavity (10) , when the beam passes through the resonator (10), a magnetic field is excited in the resonator (10), and the phase detector (1) picks up the phase information of the beam; Also includes: a frequency multiplier (2) for outputting the high-frequency phase information of the cavity of the resonant cavity (10) into a triple frequency signal; a phase detector (3), connected with the phase detector (1) and the frequency multiplier (2), to determine the phase difference relationship between the beam phase information and the high-frequency phase information; an analog/digital converter (4), connected with the phase detector (3), to convert the phase difference information output by the phase detector (3) into a digital signal; The digital signal processing unit (5) is connected to the analog/digital converter (4) and the main magnet power supply (6) of the cyclotron, and the digital signal processing unit (5) performs digital signal processing on the digital signal transmitted by the analog/digital converter (4). After processing, the control adjusts the main magnet power supply (6) to tune the magnetic field strength of the cyclotron, A filter (7) is connected between the phase detector (1) and the phase detector (3), and between the frequency multiplier (2) and the phase detector (3). An amplifier (8) is connected between the filter (7) and the phase detector (3).

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