JP5069673B2 - Particle accelerator - Google Patents

Description

  The present invention relates to a particle accelerator that accelerates charged particles such as electrons, protons, or heavy particles to generate a high-energy particle beam.

  The particle accelerator is an apparatus that generates a high-energy particle beam by accelerating charged particles such as electrons, protons, or heavy particles. In general, a particle accelerator is provided with an acceleration cavity that is excited by a high-frequency power and generates an electric field between electrodes disposed therein, and accelerates charged particles by the electric field, and a power supply device that supplies the high-frequency power to the acceleration cavity. (For example, refer to Patent Document 1). Generally, a power supply device includes a low power waveform generation unit that generates a low power waveform with controlled amplitude, frequency, phase, and the like, and an amplifier that amplifies the output waveform of the low power waveform generation unit to the power required for particle acceleration. Yes.

Japanese Unexamined Patent Publication No. 7-57898 (paragraphs 0009-0015, FIG. 1)

  Conventionally, when a low-power waveform generator having a digital signal processing unit is installed in a radiation management area where an acceleration cavity is arranged, the low-power waveform generator stops or malfunctions due to the influence of radiation generated by a beam accelerated by a particle accelerator, There is a problem that the power supply device cannot supply appropriate power to the accelerating cavity and the particles cannot be accelerated normally. For this reason, the power supply device may be covered with a metal plate such as lead to shield radiation, but there is a problem that the installation cost of the metal plate is required and the manufacturing cost is increased. In some cases, the power supply device may be arranged in a non-radiation control area, but the distance between the acceleration cavity and the power supply device becomes large, and there is a problem that the power loss in the transmission line becomes large. In addition, a coaxial tube or a waveguide that transmits a large high-frequency power necessary for the accelerating cavity is generally expensive, so that the manufacturing cost increases due to the length of the transmission line. Furthermore, since the output transmission path passes through the shielding wall that separates the radiation management area from the non-management area, a through hole is required in the shielding wall. At this time, since the shielding ability of the shielding wall is lowered, in order to obtain a sufficient effect, it is necessary to take measures such as bending the through hole and the coaxial tube in the through hole or making the shielding wall thicker. There is.

  The present invention has been made in order to solve the above-described problems, and provides a particle accelerator that realizes stable operation at a low cost.

A particle accelerator according to the present invention includes a power source device having a low power waveform generator and an amplifier that amplifies a low power output of the low power waveform generator, and an acceleration cavity that accelerates charged particles by the output of the amplifier, The low power waveform generator is a particle accelerating apparatus controlled by a computer such that charged particles are accelerated in the accelerating cavity, wherein the accelerating cavity and the amplifier are installed in a radiation management area, and the low power waveform generator includes the computer. Installing a waveform generator outside the radiation control area, installing a direct digital synthesizer that is an output of the low-power waveform generator in the radiation management area, and a cavity monitor signal for monitoring an electromagnetic field in the acceleration cavity; and The low-power waveform generator is controlled by feedback control using the cavity power monitor signal that monitors the power input to the acceleration cavity. Are your, the monitor signal is one which is a signal converted from an analog signal to a digital signal in the vicinity of the accelerating cavities.

  According to the particle accelerator of the present invention, it is possible to provide a particle accelerator that can prevent a low-power waveform generator from stopping and malfunctioning due to radiation and can realize a stable operation at low cost.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a particle accelerator according to Embodiment 1 of the present invention. In the figure, the particle accelerator includes an acceleration cavity 1 and its power supply 2, and the power supply 2 includes an amplifier 3 and a low power waveform generator 4. Here, the acceleration cavity 1 and the amplifier 3 of the power supply device 2 are installed in the radiation management area, and the low power waveform generator 4 of the power supply apparatus 2 is installed in the non-radiation management area.

  The direct digital synthesizer 5 of the low power waveform generator 4 supplies a low power output 10 to the amplifier 3 in accordance with the reference signal 7 output from the reference signal generator 6 and the command signal 9 output from the computer 8. At this time, the computer 8 uses a feedback control signal 11 or an external signal so that the waveform of the low power output 10 of the direct digital synthesizer 5 is appropriate so that the electromagnetic field generated in the accelerating cavity 1 efficiently accelerates the particles. The necessary instruction signal 9 is always calculated by the arithmetic processing unit 14 from the value set in the memory 13 by 12 and outputted. The feedback control signal 11 compares, for example, a cavity monitor signal 15 for monitoring the electromagnetic field in the acceleration cavity and a cavity input power monitor signal 17 for monitoring the waveform of the input power 16 to the cavity by the signal processing circuit 18 and performs analog-to-digital conversion. It is generated by processing by a device (A / D converter) 19. The amplifier 3 amplifies the low power output 10 to the power necessary for accelerating the particles and puts it into the acceleration cavity 1. The amplification factor of the amplifier 3 is adjusted by the amplifier output adjuster 20. Charged particles are accelerated using an electric field generated and controlled in the acceleration cavity by this input power.

According to the first embodiment, since the arithmetic processing unit 14 is installed in the non-radiation control area, it does not receive a high dose of radiation. For this reason, even when a shielding metal plate or the like is not used, the low power waveform generator 4 is not stopped or malfunctioned due to radiation.
In addition, the amplifier 3 can be installed at the same position in the radiation management area as that in the past, so that there is no need to extend the transmission line. For this reason, the power loss in the transmission line does not increase, and the additional cost of the coaxial tube / waveguide is not necessary. The signals passing through the shielding wall 21 are only the low power output 10, the cavity monitor signal 15 and the cavity input power monitor signal 17. Since these signals are low power, the transmission line has a small wire diameter. It is possible to minimize the decrease in the shielding ability of the shielding wall 21.
Further, as shown in FIG. 2, the command signals 9a and 9b output from the computer 8 may be plural, and the control target of the command signal 9b is a component of the low power waveform generator 4 such as the amplifier output regulator 20 or the like. Other elements may be used.

Embodiment 2. FIG.
FIG. 3 is a block configuration diagram showing the particle accelerator according to the second embodiment. In each figure, the same numerals indicate the same or corresponding parts. The second embodiment is different from the first embodiment in that the low-power waveform generator 4 has the reference signal generator 6 and the direct digital synthesizer 5 installed in the radiation management area. When the low power waveform generator 4 is installed in a non-radiation controlled area, the installation location is limited, and the particle accelerator and the facility where it is installed are large. The distance may need to be a long distance of about several hundred meters, for example. At this time, if the low power waveform generator 4 is arranged in the non-radiation control area, the distance from the amplifier 3 becomes large, and the output transmission path of the low power waveform generator 4 becomes long. When the output transmission line becomes longer, the power loss of the low power output 10 becomes larger, so that sufficient power may not be supplied to the amplifier 3 in some cases.

  In the second embodiment, the direct digital synthesizer 5 (the output unit of the low power waveform generator) that generates the low power output 10 is installed in the vicinity of the amplifier 3 in the radiation management area. For this reason, the transmission line of the low power output 10 may be the same length as the conventional one. Therefore, it is possible to inexpensively provide a particle accelerator that can prevent a low power waveform generator from stopping and malfunctioning due to radiation and realize stable operation without increasing power loss.

Embodiment 3 FIG.
FIG. 4 is a block configuration diagram showing the particle accelerator according to the third embodiment. In the third embodiment, the signal processing circuit 18, the analog-digital converter 19 that converts an analog signal into a digital signal, and the electric / optical signal converter 22 that converts an electric signal into an optical signal are included in an acceleration cavity in the radiation management area. 1 and 2 is different from the first and second embodiments in that an optical / electrical signal converter 23 that is disposed near 1 and converts an optical signal into an electrical signal is disposed in the low-power waveform generator 4.

  As described in the second embodiment, when the low power waveform generator 4 is arranged in the non-radiation management area, the distance from the acceleration cavity 1 may be increased. In general, high-frequency analog signals are easily affected by noise and the like when the transmission line is long, and it is difficult to accurately transmit the signals. If analog signals are used as the cavity monitor signal 15 and the cavity input power monitor signal 17 and the low power waveform generator 4 is arranged in the non-radiation management area, the transmission line becomes long and accuracy may deteriorate. At this time, the power supply device 2 cannot supply the input power 16 to the acceleration cavity 1 with high accuracy, and the acceleration cavity cannot efficiently accelerate the particles.

  In the third embodiment, the cavity monitor signal 15 and the cavity input power monitor signal 17 are digitally controlled by the signal processing circuit 18 and the A / D converter 19 installed in the vicinity of the acceleration cavity in the radiation management area. Convert to signal 11a. Further, this signal is converted into an optical signal by the electrical / optical signal converter 22 and transmitted through an optical fiber. The optical signal is converted into an electrical feedback control signal 11 b by the optical / electrical signal converter 23 installed in the non-radiation management area and input to the computer 8. For this reason, even when the transmission distance of the cavity monitor signal 15 and the cavity input power monitor signal 17 is long, it can be accurately input to the computer 8 without being affected by noise or the like. In the third embodiment, the configuration is shown in which the electrical signal converted into the digital signal is further converted into the optical signal. However, it goes without saying that sufficient accuracy may be obtained even if the electrical signal is transmitted.

Embodiment 4 FIG.
FIG. 5 is a block diagram showing a particle acceleration apparatus according to the fourth embodiment. In the fourth embodiment, the transmission paths for the cavity monitor signal 15 and the cavity input power monitor signal 17 are cooled. For example, as shown in FIG. 6, cooling water 26 circulated between a jacket 25 having a coaxial structure with the transmission path 24 as shown in FIG. Has been achieved. The transmission path 24 includes an inner conductor 27, a dielectric 28, an outer conductor 29, and a coating 30.

  The effect by Embodiment 4 is demonstrated. In general, in an analog signal transmission line, the electrical length, which is a value obtained by dividing the length of the wavelength of the electrical signal on the transmission line by the physical length of the transmission line, varies depending on the influence of the ambient temperature. When the electrical length of the transmission line changes, the phases of the cavity monitor signal 15 that reaches the signal processing circuit at a certain time and the cavity input power monitor signal 17 change. For this reason, when using PLL (Phase Lock Loop) control or the like that controls the frequency by comparing the phases of two signals, it is affected by the change in the electrical length of the transmission line, and the original two signal levels are affected. In some cases, the phase difference cannot be obtained with high accuracy. The change in electrical length generally increases as the transmission line becomes longer. Therefore, when the low-power waveform generator 4 is arranged in a non-radiation management area, the transmission line becomes longer, and this influence is increased. In the fourth embodiment, since the transmission paths for the cavity monitor signal 15 and the cavity input power monitor signal 17 are cooled, the change in the electrical length becomes small. For this reason, the phase change of the cavity monitor signal 15 and the cavity input power monitor signal 17 due to the temperature change around the transmission line can also be reduced, the influence of the ambient temperature change is small, and the waveform of the low power output 10 can be appropriately set. Can be controlled.

Embodiment 5 FIG.
FIG. 7 is a block configuration diagram showing the particle acceleration apparatus according to the fifth embodiment. In the fifth embodiment, the transmission lines of the cavity monitor signal 15 and the cavity input power monitor signal 17 are installed in the vicinity of the place where these monitor signals are obtained (in the vicinity of the acceleration cavity in the radiation management area). A signal such as a sine wave having a frequency band different from that of the monitor signal is mixed from the device 31 and transmitted to the signal processing circuit 18 together with the monitor signal. The two signals respectively input from the transmitter 31 to the two transmission paths are, for example, signals having the same phase at a certain point or signals having a clear phase difference, such as branching one signal.

  In the signal processing circuit 18, the cavity monitor signal 15, the cavity input power monitor signal 17, and the signal from the transmitter 31 are separated by the frequency band, and two signals output from the transmitter 31 to the two transmission paths are two. A phase shift (phase difference of the signal from the transmitter) when passing through the transmission line is detected. This shifted phase (phase difference) is converted into a phase difference in the frequency band of the two monitor signals, and corrected by subtracting from the phase difference during phase comparison in the PLL control of the cavity monitor signal 15 and the cavity input power monitor 17. And output to the A / D converter 11. At this time, the phase difference between the two monitor signals and the phase difference between the signals from the transmitter 31 are converted into digital signals by the A / D converter 11 and input to the computer 8, and the phase difference is corrected by the computer 8. May be.

  In the fifth embodiment, as described in the fourth embodiment, even when the electrical lengths of the transmission paths of the two monitor signals are changed, the change in the electrical length is transmitted from the transmitter 31 to the two A signal having a frequency band different from that of the monitor signal is input to the transmission path of the monitor signal, detected by the phase difference between the input signals, and a change in electrical length is corrected to control the low power waveform device. For this reason, the influence of the change in ambient temperature is small, and the waveform of the low power output 10 can be appropriately controlled.

It is a block block diagram which shows the particle | grain acceleration apparatus which is Embodiment 1 of this invention. It is a block block diagram which shows the other particle acceleration apparatus which is Embodiment 1. FIG. It is a block block diagram which shows the particle | grain acceleration apparatus which is Embodiment 2. FIG. FIG. 6 is a block configuration diagram illustrating a particle acceleration apparatus according to a third embodiment. FIG. 6 is a block configuration diagram illustrating a particle acceleration apparatus according to a fourth embodiment. FIG. 10 is a partial cross-sectional view showing a cooled transmission line in the particle accelerator of the fourth embodiment. FIG. 10 is a block configuration diagram illustrating a particle acceleration apparatus according to a fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Acceleration cavity 2 Power supply device 3 Amplifier 4 Low power waveform generator 5 Direct digital synthesizer 6 Reference signal generator 8 Computer 13 Memory 14 Arithmetic processing device 18 Signal processing circuit 19 Analog-digital converter 20 Amplifier output regulator 21 Shielding wall 22 Electricity / Optical signal converter 23 Optical / electrical signal converter 24 Transmission path 25 Jacket 26 Cooling water 27 Inner conductor 28 Dielectric 29 Outer conductor 30 Cover 31 Transmitter

Claims (1)

A power supply apparatus having a low power waveform generator and an amplifier for amplifying a low power output of the low power waveform generator, and an acceleration cavity for accelerating charged particles by the output of the amplifier, wherein the low power waveform generator includes the acceleration In a particle accelerator that is controlled by a computer so that charged particles are accelerated in the cavity,
The acceleration cavity and the amplifier are installed in a radiation management area, the low power waveform generator having the computer is installed outside the radiation management area , and a direct digital synthesizer that is an output unit of the low power waveform generator is used as a radiation. Set up in a controlled area,
The low power waveform generator is controlled by feedback control using a cavity monitor signal for monitoring an electromagnetic field in the acceleration cavity and a cavity input power monitor signal for monitoring input power to the acceleration cavity, and the monitor signal is 2. A particle accelerator according to claim 1, wherein the particle accelerator is a signal converted from an analog signal to a digital signal in the vicinity of the acceleration cavity .

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