CN109893777B - Phase detector and proton beam phase stabilizing device comprising same - Google Patents
Phase detector and proton beam phase stabilizing device comprising same Download PDFInfo
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- CN109893777B CN109893777B CN201910142792.9A CN201910142792A CN109893777B CN 109893777 B CN109893777 B CN 109893777B CN 201910142792 A CN201910142792 A CN 201910142792A CN 109893777 B CN109893777 B CN 109893777B
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Abstract
The invention relates to the technical field of cyclotrons, and discloses a phase detector, a proton beam phase stabilizing device comprising the phase detector and a control method. The resonant cavity of the phase detector picks up the phase information of the beam and carries out phase discrimination with the triple frequency signal of the resonant cavity, and the phase-discriminated signal is processed by the digital signal processing unit and then controls and adjusts the main magnet power supply, so that the rapid intelligent matching of the phase information of the beam and the high-frequency phase information is realized, and the technical guarantee is provided for a beam stabilizing system in proton treatment equipment.
Description
Technical Field
The invention relates to the technical field of cyclotrons, in particular to a phase detector and a proton beam phase stabilizing device comprising the same.
Background
In proton treatment, in order to realize accurate transmission of treatment dosage, the source of the beam, namely the accelerator end, has high requirements on the quality and stability of the proton beam besides high requirements on the tumor diagnosis precision of a patient and a subsequent beam transmission system.
In general, parameters such as envelope, dispersion and current intensity of a beam are optimized in the design, construction and debugging stages of an accelerator, and the requirements of proton treatment on the beam quality can be completely met. However, since the proton treatment system needs to operate for a long time, in the long-term operation process, the stability of the beam current of the accelerator is adversely affected by the heating of accelerator components (such as a high-frequency cavity) and external signal interference, so that parameters such as the beam current intensity and dispersion are changed, which is disadvantageous to the accurate transmission of the dosage required by the proton treatment.
In order to solve the above problems, in a laboratory environment, a professional operator and an accelerator specialist can perform human intervention to readjust accelerator parameters and optimize beam parameters, but it is not practical for proton treatment equipment which is operated in a hospital on a large scale in the future, and therefore, an automatic beam stability measurement and feedback adjustment system needs to be developed on the basis of fully researching factors affecting beam stability.
Disclosure of Invention
The first purpose of the invention is to provide a phase detector, which adopts a cavity structure and can be installed on a beam line, and a beam passes through the middle of a cavity, so that resonance can be better caused, and signals are more obvious.
The above object of the present invention is achieved by the following technical solutions:
the phase detector comprises a cylindrical cavity barrel with a closed end surface and a hollow inner rod positioned in the axis position in the cavity barrel, wherein one end of the inner rod is open, the other end of the inner rod is closed, a resonant cavity is arranged in the inner rod, an adjusting ring is arranged at the open end of the inner rod, and a first opening communicated with the inner rod resonant cavity is formed in the end surface of the cavity barrel corresponding to the open end of the inner rod.
By adopting the technical scheme, the non-blocking phase detector is formed by adopting a cavity type structure and can be installed on a beam line, the beam passes through the middle of the cavity, the open end of the inner rod forms an open end, the closed end forms a short-circuit end, the phase information of the beam is picked up at the short-circuit end, resonance can be better caused, and signals are more obvious.
In some embodiments, the end surfaces of the two ends of the cavity barrel are respectively provided with a cover plate which is in sealing connection with the cavity barrel.
By adopting the technical scheme, the end surface and the circumferential surface of the cavity barrel adopt a split structure, so that the installation and the maintenance of the inner rod in the cavity barrel are facilitated.
In some embodiments, the inner rod is a hollow tube with two open ends, two ends of the hollow tube are connected to the cover plate, a second opening leading into the inner rod resonant cavity is formed in the cover plate corresponding to the closed end of the inner rod, a blind cover is covered on the cover plate corresponding to the second opening, the inner rod is connected to the cover plates at two ends in a sealing manner, and the blind cover is connected to the cover plates in a sealing manner.
By adopting the technical scheme, the resonant cavity forms a sealed ring shape, so that the vacuumizing is realized, the interference of external factors on the beam current is avoided, and the accuracy of the phase information of the picked beam current is ensured.
In some embodiments, a vacuum quick release flange is attached to the first opening outside the chamber barrel.
By adopting the technical scheme, the phase detector is quickly installed, and meanwhile, the sealing performance of a beam inlet is guaranteed.
In some embodiments, the axial length of the cartridge is equal to a quarter wavelength.
By adopting the technical scheme, the length of the cavity barrel is controlled, the phase detector is convenient to mount on a beam line, and meanwhile, the interference from the fundamental wave frequency of the high-frequency cavity of the accelerator is avoided.
A second object of the present invention is to provide a proton beam phase stabilizing apparatus including the phase detector, which can automatically measure beam phase information and perform feedback adjustment.
The above object of the present invention is achieved by the following technical solutions: the phase detector is arranged on a beam transport line of the cyclotron and is provided with a resonant cavity, a beam excites a magnetic field in the resonant cavity when passing through the resonant cavity, and the phase detector picks up beam phase information;
in addition, the method also comprises the following steps:
the frequency multiplier is used for outputting the high-frequency phase information of the cavity of the resonant cavity into a frequency tripling signal;
the phase discriminator is connected with the phase detector and the frequency multiplier and used for determining the phase difference relationship between the beam phase information and the high-frequency phase information;
the analog/digital converter is connected with the phase discriminator and converts the phase difference information output by the phase discriminator into a digital signal;
and the digital signal processing unit is connected with the analog-to-digital converter and a main magnet power supply of the cyclotron, and controls and adjusts the main magnet power supply to tune the magnetic field intensity of the cyclotron after processing the digital signal transmitted by the analog-to-digital converter.
By adopting the technical scheme, the resonant cavity of the phase detector picks up the beam phase information and the resonant cavity frequency tripling signal to carry out phase discrimination, and the phase discriminated signal is processed by the digital signal processing unit and then controls and adjusts the main magnet power supply, so that the beam phase information and the high-frequency phase information are rapidly and intelligently matched, and technical guarantee is provided for a beam stabilizing system in the proton treatment equipment.
In some embodiments, a filter is connected between the phase detector and the phase detector, and between the frequency multiplier and the phase detector.
By adopting the technical scheme, the filter can effectively filter the interference signals of the phase information of the pickup beam, so that the effective information is ensured, and the pickup quality is improved.
In some embodiments, an amplifier is connected between the filter and the phase detector.
Because the phase signal intensity is weaker, by adopting the technical scheme, the phase signal can be amplified, and the phase discrimination comparison in the later period is facilitated.
In conclusion, the beneficial technical effects of the invention are as follows:
1. the phase detector is arranged in a cavity type structure and can be arranged on a beam line, and a beam passes through the middle of the cavity, so that resonance can be better caused, and signals are more obvious;
2. the resonant cavity of the phase detector is adopted to pick up beam phase information and resonant cavity frequency tripling signals for phase discrimination, and the phase discriminated signals are processed by the digital signal processing unit and then control and adjust the main magnet power supply, so that the beam phase information and the high-frequency phase information are rapidly and intelligently matched, and technical guarantee is provided for a beam stabilizing system in proton treatment equipment.
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 stabilizing device provided by the present invention.
In the figure, 1, a phase detector; 10. a resonant cavity; 2. a frequency multiplier; 3. a phase discriminator; 4. an analog/digital converter; 5. a digital signal processing unit; 6. a main magnet power supply; 7. a filter; 8. an amplifier; 101. a chamber cylinder; 102. an inner rod; 1011. a cover plate; 1021. an adjusting ring; 1012. a first opening; 1014. a blind cover; 121. and (4) vacuum quick-release flanges.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
The invention discloses a phase detector, as shown in fig. 1 and fig. 2, comprising a cylindrical cavity cylinder 101 and a hollow inner rod 102 penetrating through the axis position of the cavity cylinder 101, wherein the inner rod 102 is a hollow pipe body with two open ends, the interior of the hollow pipe body is a resonant cavity 10, two end faces of the cavity cylinder 101 are respectively provided with a cover plate 1011, two ends of the inner rod 102 are hermetically connected with the cover plates 1011, the cover plates 1011 at two ends are respectively provided with a first opening 1012 and a second opening (not shown in the figure) which are led into the resonant cavity 10 of the inner rod 102, the cover plate 1011 with the second opening is provided with a blind cover 1014 corresponding to the second opening, the blind cover 1014 is hermetically connected with the cover plate 1011, so that the inner rod 102 is arranged corresponding. As shown in FIG. 2, an adjusting ring 1021 is arranged at the opening end of the inner rod 102, and a vacuum quick release flange 121 is connected to the first hole 1012 at the outer side of the cavity barrel 101. The structure forms a non-blocking phase detector, the open end of the inner rod 102 forms an open end, the closed end forms a short-circuit end, the phase detector is arranged on a beam transport line of the cyclotron, a beam is emitted into the inner rod 102 from the end of the vacuum quick-release flange 121, the beam excites a magnetic field when passing through a resonant cavity, and beam phase information is picked up at the short-circuit end to realize the pickup of the beam phase information.
In order to control the length of the phase detector and at the same time avoid interference from the fundamental frequency of the high-frequency cavity of the accelerator, the axial length of the phase detector 1 is equal to a quarter wavelength, i.e. its length is about 0.35m, and at the same time the sampling frequency of the beam phase information is chosen to be the third harmonic frequency of 71.5MHz, which is 214.5 MHz.
As shown in FIG. 3, the invention also discloses a proton beam phase stabilizing device comprising the phase detector, the phase detector 1 is arranged on the beam transport line of the cyclotron and is provided with a resonant cavity 10, a beam excites a magnetic field in the resonant cavity 10 when passing through the resonant cavity 10, and the phase detector 1 picks up beam phase information
The frequency multiplier 2 is used for outputting the high-frequency phase information of the cavity of the resonant cavity 10 into a frequency tripled signal;
in addition, the method also comprises the following steps:
the phase discriminator 3 is connected with the phase detector 1 and the frequency multiplier 2 and determines the phase difference relationship between the beam phase information and the high-frequency phase information;
the filter 7 is positioned between the high-frequency phase detector 1 and the phase discriminator 3, and between the frequency multiplier 2 and the phase discriminator 3, and is used for effectively filtering interference signals of the picked beam phase information, ensuring effective information and improving the pickup quality;
the amplifier 8 is positioned between the filter 7 and the phase discriminator 3 to amplify the phase signal, so that the phase discrimination comparison in the later period is facilitated;
an analog/digital converter 4 connected to the phase detector 3 to convert the phase difference information output from the phase detector 3 into a digital signal;
and the digital signal processing unit 5 is connected with the analog-digital converter 4 and a main magnet power supply 6 of the cyclotron, and the digital signal processing unit 5 controls and adjusts the main magnet power supply 6 after processing the digital signal transmitted by the analog-digital converter 4 so as to tune the magnetic field intensity of the cyclotron.
A beam excites a magnetic field when passing through a resonant cavity 10 of a phase detector 1, a high-frequency phase detector 1 picks up beam phase information and uses the beam phase information as the input of a feedback loop for controlling the magnetic field intensity, the sampling frequency of the beam phase information selects the third harmonic frequency of the beam phase information, the high-frequency of the cyclotron is 71.5MHz, and the third harmonic frequency of the cyclotron is 214.5 MHz; the frequency multiplier 2 converts the cavity high-frequency phase information of the resonant cavity 10 into a frequency tripling signal and outputs the frequency tripling signal, that is, in the embodiment of the invention, if the cavity high-frequency phase information frequency of the resonant cavity 10 is 71.5MHz, the frequency tripling signal output frequency is 214.5 MHz; interference signals of the beam phase information and the high-frequency phase information are effectively filtered through a filter 7, the beam phase information is subjected to two-stage amplification through an amplifier 8, and then is subjected to amplitude limiting amplification and zero crossing detection; the filtered and amplified beam phase information and the filtered high-frequency phase information are sent to a phase discriminator 3 consisting of double-balanced mixers, and output signals are I components and Q components related to the phase difference between the I components and the Q components; the phase difference information after phase discrimination is transmitted to an analog-to-digital converter 4 to be converted into a digital signal, and then the digital signal is sent to a digital signal processing unit 5, and the digital signal processing unit 5 controls and adjusts a main magnet power supply 6 of the cyclotron according to the phase discrimination result so as to tune the magnetic field intensity of the cyclotron, thereby realizing the quick and intelligent matching of beam phase and high-frequency phase.
In order to reduce the influence of external noise on a system, all circuit boards of the phase detector and the proton beam current phase stabilizing device comprising the phase detector are arranged in VME boxes with the heights of 1U, so that good electromagnetic shielding can be provided, meanwhile, a high-precision linear power supply is adopted for supplying power to reduce the adverse effect of power supply ripples and the like on sensitivity, and in addition, 1 inductor is additionally arranged in a power supply line of a high-frequency device to prevent possible interference on other parts.
The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.
Claims (4)
1. The phase detector is characterized by comprising a cylindrical cavity barrel (101) and a hollow inner rod (102) penetrating through the axis position of the cavity barrel (101), wherein the inner rod (102) is a hollow pipe body with two open ends, a resonant cavity (10) is arranged in the hollow pipe body, two end faces of the cavity barrel (101) are respectively provided with a cover plate (1011), two ends of the inner rod (102) are hermetically connected with the cover plates (1011), the cover plates (1011) at two ends are respectively provided with a first opening (1012) and a second opening which are communicated with the resonant cavity (10) of the inner rod (102), a blind cover (1014) is arranged on the cover plate (1011) with the second opening and covers the second opening, the blind cover (1014) is hermetically connected with the cover plate (1011), and therefore the inner rod (102) is arranged corresponding to the opening at the end of the first opening (1012), and the other end is arranged in a closed.
2. Phase detector according to claim 1, characterized in that a vacuum quick-release flange (121) is connected to the first opening (1012) outside the chamber tube (101).
3. Phase detector according to claim 1, characterized in that the axial length of the bore (101) is equal to a quarter wavelength.
4. A proton beam phase stabilizing arrangement comprising a phase detector according to any one of claims 1 to 3, characterized in that the phase detector (1) is mounted on the beam transport line of the cyclotron and has a resonant cavity (10), a magnetic field is excited in the resonant cavity (10) when the beam passes through the resonant cavity (10), and the phase detector (1) picks up beam phase information;
in addition, the method also comprises the following steps:
the frequency multiplier (2) is used for converting the high-frequency phase information of the cavity of the resonant cavity (10) into a frequency tripled signal and outputting the frequency tripled signal;
the phase discriminator (3) is connected with the phase detector (1) and the frequency multiplier (2) and determines the phase difference relationship between the beam phase information and the high-frequency phase information;
the analog/digital converter (4) is connected with the phase discriminator (3) and converts the phase difference information output by the phase discriminator (3) into a digital signal;
the digital signal processing unit (5) is connected with the analog-digital converter (4) and a main magnet power supply (6) of the cyclotron, the digital signal processing unit (5) controls and adjusts the main magnet power supply (6) to tune the magnetic field intensity of the cyclotron after processing the digital signal transmitted by the analog-digital converter (4),
the phase detector (1) and between phase discriminator (3), and frequency multiplier (2) with be connected with wave filter (7) between phase discriminator (3), wave filter (7) with be connected with amplifier (8) between phase discriminator (3).
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| CN201910142792.9A CN109893777B (en) | 2019-02-26 | 2019-02-26 | Phase detector and proton beam phase stabilizing device comprising same |
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| CN110677976A (en) * | 2019-11-16 | 2020-01-10 | 中国原子能科学研究院 | Cavity structure for picking up beam phase signals based on inductance probe |
| CN111896993A (en) * | 2020-07-23 | 2020-11-06 | 苏州核道核能技术有限公司 | Ion ray angular distribution ionization chamber detector |
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| JPH08316000A (en) * | 1995-05-12 | 1996-11-29 | Toshiba Corp | High frequency accelerating system |
| CN102510655B (en) * | 2011-09-22 | 2014-06-04 | 湖北久瑞核技术股份有限公司 | Electron beam current control device of electron accelerator |
| CN202565565U (en) * | 2012-03-28 | 2012-11-28 | 中国科学院上海应用物理研究所 | Electron beam sub-harmonic buncher |
| US9603235B2 (en) * | 2012-07-27 | 2017-03-21 | Massachusetts Institute Of Technology | Phase-lock loop synchronization between beam orbit and RF drive in synchrocyclotrons |
| CN106211539B (en) * | 2016-07-29 | 2019-04-19 | 中国原子能科学研究院 | A kind of digital stabilising arrangement of cyclotron ejected beam phase and its method |
| CN106231777B (en) * | 2016-07-29 | 2019-01-29 | 中国原子能科学研究院 | A kind of signal source of high stability of superconducting cyclotron |
| EP3319403B1 (en) * | 2016-11-07 | 2022-01-05 | Ion Beam Applications S.A. | Compact electron accelerator comprising first and second half shells |
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