JPH11150000A - High frequency accelerating device and annular accelerator using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency acceleration system capable of adjusting impedance with a circuit element having low voltage resistance or measuring accelerating gap voltage even when the accelerating gap voltage is high. SOLUTION: A high frequency acceleration system 1 is constituted with an accelerating gap 2 for inducing an accelerating electric field of charged particle beams; a central conductor 3 forming a path of the charged particle beams and having the accelerating gap 2; and an annular magnetic body core 4 crossing in a chain state as the central conductor 3. The magnetic body core 4 is divided into a plurality of groups and each group crosses in a chain state as a loop antenna 5. An impedance adjusting means 6 or an accelerating gap voltage measuring means 7 is connected to each loop antenna 5. The voltage being applied to these has a value obtained by dividing the voltage value of the accelerating gap 2 by the number of divided groups, and in this example, it is 1/6 the accelerating gap voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the structure of a high-frequency accelerator for accelerating a charged particle beam, and more particularly to the structure of a high-frequency accelerator for a synchrotron for accelerating an ion beam.

[0002]

2. Description of the Related Art In order to accelerate a charged particle beam with high efficiency, impedance matching between a high-frequency accelerator and a power source is essential. Also, for stable acceleration of the charged particle beam, constant monitoring of the acceleration gap voltage is indispensable. In a conventional high frequency accelerator, as shown in FIG. 8, a circuit element for impedance adjustment and a circuit element for measuring acceleration gap voltage are directly connected to the acceleration gap. FIG. 8A shows an example of a tuned high-frequency accelerator.
A capacitor is connected to the acceleration gap, and the resonance frequency variable range is set in the operation frequency range. FIG. 8B shows an example of a non-tuning type high-frequency accelerator, in which a resistor is connected to the acceleration gap to extend the operable range to the entire operating frequency range. FIG.
(C) shows an example in which a capacitive voltage divider is connected to the acceleration gap to measure the acceleration gap voltage.

The above prior arts are described in "OHO'89 High Energy Accelerator Seminar", Chapter 5, High Frequency Accelerator of Proton Synchrotron (pp. 19-32, published by High Energy Accelerator Science Research Encouragement Society) and "Conceptual Design". of a
Proton Therapy SynchrotronFor Loma Linda Universit
y Medical Center ”(p.25-p.27, Fermi NationalAccel
erator Laboratory, 1986).

[0004]

In a conventional high-frequency accelerator, a circuit element for impedance adjustment and a circuit element for measuring an acceleration gap voltage are directly connected to the acceleration gap. Since the voltage of the acceleration gap is high, these circuit elements are required to have a high withstand voltage. In particular, a large vacuum capacitor with high withstand voltage is required for the capacitor. For this reason,
The structure around the acceleration gap is complicated, large, and difficult to assemble and disassemble. Further, since it is difficult to manufacture a high-frequency resistor having high withstand voltage and high power consumption, it has been difficult to obtain a high accelerating gap voltage in a non-tuned high-frequency accelerator.

An object of the present invention is to provide a high-frequency accelerator which is small in size and easy to assemble and disassemble, which enables impedance adjustment and acceleration gap voltage measurement with circuit elements having a low withstand voltage even when the acceleration gap voltage is high.

[0006]

According to a first aspect of the present invention, there is provided a high-frequency accelerator, wherein the loop antenna includes at least one of the magnetic core groups including a plurality of magnetic cores. And the impedance adjusting means is provided so as to intersect with the magnetic cores of the group in a chain, and the impedance adjusting means is connected to the loop antenna.

A second feature of the high-frequency accelerator according to the present invention resides in that a loop antenna is provided so as to intersect at least one magnetic core in a chain shape, and impedance adjusting means is connected to the loop antenna.

According to the above feature, the voltage applied to one impedance adjusting means is reduced, and the impedance adjusting means can be constituted by a circuit element having a low withstand voltage, so that the high-frequency accelerator can be downsized.

A third aspect of the invention is characterized in that the loop antenna is provided in at least one of the magnetic core groups including a plurality of magnetic cores in a chain with the magnetic cores of the group. A voltage measuring means provided to cross and measure the voltage of the acceleration gap is connected to the loop antenna.

The high-frequency accelerator according to claim 4 is characterized in that a loop antenna is provided so as to intersect at least one magnetic core in a chain shape, and voltage measuring means for measuring a voltage in an acceleration gap is provided in the loop antenna. Have been connected.

According to the above feature, the voltage applied to the voltage measuring means is reduced, and the voltage measuring means can be constituted by a circuit element having a low withstand voltage, so that the high-frequency accelerator can be downsized. Further, if at least one voltage measuring means is provided, the voltage of the acceleration gap can be measured, so that the high-frequency accelerator can be further downsized.

A feature of the high-frequency accelerator according to claim 5 is that voltage measuring means is connected in series.

According to the above feature, the same operation as that of the high-frequency accelerator according to the third or fourth aspect can be obtained, and the voltage of the acceleration gap can be measured accurately.

According to a sixth aspect of the present invention, the annular accelerator is provided with the high-frequency accelerator according to the first, second, third, fourth or fifth aspect.

[0015]

(Embodiment 1) FIG. 1 shows a first embodiment of the present invention.
FIG. 4 is an explanatory diagram of a high-frequency accelerator according to the embodiment. The high-frequency accelerator 1 includes an acceleration gap 2 for inducing an acceleration electric field of a charged particle beam, a center conductor 3 forming a passage for the charged particle beam and having an acceleration gap, and an annular magnetic body intersecting the center conductor in a chain shape. And a core 4. The magnetic core 4 is divided into a plurality of groups, each of which has a loop antenna 5.
And cross in a chain. Each loop antenna is connected to impedance adjustment means 6 or acceleration gap voltage measurement means 7. Two loop antennas may be provided for each group of magnetic cores, and impedance adjustment and acceleration gap voltage measurement may be connected to each.

The impedance adjusting means 6 is composed of a capacitor, a resistor, an inductance, or a network thereof. For example, a capacitor or an inductance is used to adjust the resonance frequency, and a resistor is used to adjust the sharpness Q value of the resonance.

On the other hand, the accelerating gap voltage measuring means 7 comprises a capacitive voltage divider, a resistive voltage divider, or a combination thereof. The voltage applied to the impedance adjusting means 6 or the accelerating gap voltage measuring means 7 is a value obtained by dividing the voltage of the accelerating gap 2 by the number of divided groups of the magnetic core. In this embodiment, the voltage is 1/6 of the accelerating gap voltage. Becomes

The effect of reducing the applied voltage increases as the number of divided groups increases. When the magnetic core is ultimately divided into individual magnetic cores, the applied voltage is up to a value obtained by dividing the acceleration gap voltage by the number of magnetic cores. It is reduced.

Since the voltage applied to the impedance adjusting means 6 or the accelerating gap voltage measuring means 7 becomes low,
The impedance adjusting means 6 or the accelerating gap voltage measuring means 7 may have a low withstand voltage and can be miniaturized.

In this embodiment, a loop antenna is provided for each divided group of the magnetic material and the impedance adjusting means 6 or the accelerating gap voltage measuring means 7 is connected, but this is not always necessary. For example, when the influence on the high-frequency characteristics due to the individual difference between the magnetic cores and the difference in the installation position can be neglected, a single set of loop antenna and measuring means is sufficient for measuring the acceleration gap voltage. If the number of the impedance adjusting means 6 or the accelerating gap voltage measuring means 7 is reduced, the high-frequency accelerator becomes more compact.

When the number of the impedance adjusting means 6 is increased, the impedance can be adjusted more accurately over the entire length of the high-frequency accelerator.

According to this embodiment, even when the acceleration gap voltage of the high-frequency accelerator is as high as several tens of kV, impedance adjustment and voltage measurement of the acceleration gap can be achieved with a commercially available small high-frequency circuit element having a withstand voltage of 1 kV or less. As a result, a high-frequency accelerator that is small and easy to assemble and disassemble can be realized.

(Embodiment 2) FIG. 2 is an explanatory view of a high-frequency accelerator according to a second embodiment of the present invention. In this embodiment, the loop antenna 5 is provided by grouping a plurality of groups of the divided magnetic cores, and the impedance adjusting unit 6 or the accelerating gap voltage measuring unit 7 is connected thereto. In the present embodiment, the voltage applied to them is の of the voltage of the acceleration gap 2 and the effect of reducing the applied voltage is smaller than in the first embodiment. 7 may have low withstand voltage and can be miniaturized. Also. Since the number of loop antennas, impedance adjusting means, and accelerating gap voltage measuring means can be reduced, the high-frequency accelerator can be downsized.

(Embodiment 3) FIG. 3 is an explanatory view of a high-frequency accelerator according to a third embodiment of the present invention. In the present embodiment, the loop antenna 5 is provided by integrating all the magnetic material cores, and the impedance adjusting means 6 or the measuring means 7 of the acceleration gap voltage is connected. A power feeding loop antenna 9 is used to feed power from the high frequency power supply 8 to the high frequency accelerator 1. In this case, the voltage applied to the impedance adjusting means 6 or the acceleration gap voltage measuring means 7 is the same as the voltage of the acceleration gap 2, and there is no effect of reducing the applied voltage.
However, since the feed line, the vacuum capacitor, or the resistor connected to the acceleration gap in the conventional high-frequency accelerator (FIG. 8) is not provided, the space in the acceleration gap can be effectively used for loading the magnetic material. As a result, the overall length of the device can be reduced.
Furthermore, since the center conductor 3 has no object to be connected, it can be completely structurally free from the main body of the high-frequency accelerator. As a result, assembly and disassembly of the device are facilitated. The effect of the present embodiment can be similarly achieved by using a loop antenna for power supply from the high-frequency power supply 8 in the first and second embodiments.

(Embodiment 4) FIG. 4 is an explanatory view of a high-frequency accelerator according to a fourth embodiment of the present invention. In this embodiment, the magnetic core 4 is divided into a plurality of groups, each of which intersects the feeding loop antenna 9 in a chain shape. Electric power from the multi-channel high-frequency power supply 8 is supplied to the high-frequency accelerator 1 through the feeding loop antenna 9. The impedance adjusting means 6 or the accelerating gap voltage measuring means 7
It is connected to the feeding loop antenna 9. The induced voltage in the acceleration gap 2 is the sum of the voltages applied to the respective feeding loop antennas 9, and the voltage applied to the impedance adjusting means 6 or the acceleration gap voltage measuring means 7 is obtained by dividing the acceleration gap voltage into the divided groups of the magnetic cores. It is a value divided by a number. As in the first embodiment, since the voltage applied to the impedance adjusting means 6 or the acceleration gap voltage measuring means 7 is reduced, the impedance adjusting means 6 or the accelerating gap voltage measuring means 7 is reduced.
Can have a low withstand voltage and can be miniaturized.

In this embodiment, there is no need to separately provide a loop antenna for impedance adjustment or acceleration gap voltage measurement, so that the configuration of the high-frequency accelerator can be simplified.

(Embodiment 5) FIG. 5 is an explanatory view of a high-frequency accelerator according to a fifth embodiment of the present invention. Magnetic core 4
Are divided into a plurality of groups, each of which crosses a plurality of loop antennas 5 and 9 in a chain shape. The impedance adjusting means 6a and 6c connected to each loop antenna are connected to the other impedance adjusting means 6b and the magnetic core 4 (L
(C parallel circuit) to form a network. In this embodiment, a bridge T-type network is formed, and the frequency characteristics of the voltage induced in the acceleration gap 2 can be adjusted.

The voltage applied to each loop antenna is a value obtained by dividing the accelerating gap voltage by the number of divided groups of the magnetic core, and the voltage applied to the impedance adjusting means 6 becomes lower as in the first embodiment. Therefore, the impedance adjusting means 6 may have low withstand voltage and can be downsized.

As in the first embodiment, if the number of the impedance adjusting means 6 is reduced, the high-frequency accelerator becomes smaller, and if the number is increased, the impedance is more accurately adjusted over the entire length of the high-frequency accelerator. can do.

The above-described impedance adjustment circuit network can be integrated into the impedance adjustment means 6c, so that the high-frequency accelerator becomes more compact. (Embodiment 6) FIG. 6 is an explanatory view of a high-frequency accelerator according to a sixth embodiment of the present invention. The magnetic core 4 is divided into a plurality of groups, each of which intersects the loop antenna 5 in a chain shape. Each loop antenna is connected to an acceleration gap voltage measuring means 7.

The acceleration gap voltage measuring means 7 is a capacitive voltage divider. In the present embodiment, the capacitive voltage dividers located on the left and right sides of the acceleration gap are connected in series, and these two signals are combined by the differential amplifier 14 and at the same time a long transmission line to the control room is driven. The capacitor 15 is connected to adjust the voltage division ratio. The provision of the differential amplifier 14 and the capacitor 15 simplifies the subsequent signal processing system. Increasing the number of capacitive voltage dividers connected in series,
If the voltage in the acceleration gap can be accurately measured and reduced, the RF accelerator becomes more compact.

As in the first embodiment, the voltage applied to each loop antenna is a value obtained by dividing the acceleration gap voltage by the number of divided groups of the magnetic core. The acceleration gap voltage measuring means 7
Can have a low withstand voltage and can be miniaturized.

In this embodiment, a capacitive voltage divider is used, but a resistive voltage divider may be used.

(Embodiment 7) FIG. 7 is an explanatory view of a ring accelerator according to a seventh embodiment of the present invention. The annular accelerator shown in the present embodiment includes an injector 10 for injecting a charged particle beam transported from a pre-stage accelerator into a ring, a deflection electromagnet 1 for deflecting the trajectory of the charged particle beam and orbiting along the ring.
1, a focusing electromagnet 12 for giving a focusing force so that a charged particle beam does not spread, a high-frequency accelerator for accelerating an incident beam to a required energy, and an emitter 13 for taking out a charged particle beam having reached a predetermined energy out of a ring. Be composed.

In order to stably accelerate the charged particle beam by the high-frequency accelerator, it is necessary to increase the exciting current of the bending electromagnet and the focusing electromagnet in synchronization with the acceleration. In addition, since the ring circulation cycle of the charged particle beam is shortened with acceleration, the frequency of the acceleration gap voltage of the high-frequency accelerator, that is, the output frequency of the high-frequency power supply needs to be correspondingly increased. Therefore, constant monitoring of the acceleration gap voltage is indispensable for stable acceleration of the charged particle beam. Further, in order to accelerate a charged particle beam with high efficiency, impedance matching between a high-frequency accelerator and a power supply over a wide frequency band is essential.
The above object can be easily achieved by providing the annular accelerator with the high-frequency accelerator described in the first to sixth embodiments. In particular, the acceleration gap voltage of the high-frequency accelerator is several tens kV.
Even if it is high, since a resistor with a realistic withstand voltage and power consumption (500 V-1 kW) can be used, a non-tuned high-frequency accelerator can be adopted, and the charged particle beam is adjusted to the ring circulation cycle. That is, it is not necessary to control the resonance frequency of the high-frequency accelerator according to the output frequency of the high-frequency power supply, and the operation control of the annular accelerator becomes easy.

[0036]

According to the high frequency accelerator of the first aspect, at least one of the magnetic core groups including a plurality of magnetic cores includes the loop antenna and the magnetic core of the group. Since the impedance adjusting means is connected to the loop antenna, the voltage applied to one impedance adjusting means becomes low, and the impedance adjusting means can be constituted by a circuit element having a low withstand voltage. Therefore, the high-frequency accelerator can be downsized.

According to the high-frequency accelerator of the second aspect, the loop antenna is provided to intersect at least one magnetic core in a chain shape, and the impedance adjusting means is connected to the loop antenna. The same function and effect as those of the high-frequency accelerator of item 1 can be obtained.

According to the third aspect of the present invention, the loop antenna is provided in at least one of the magnetic core groups including a plurality of magnetic cores in a chain with the magnetic cores of the group. The voltage measuring means for measuring the voltage of the acceleration gap, which is provided to intersect, is connected to the loop antenna, so that the voltage applied to the voltage measuring means is reduced, and the voltage measuring means is a circuit element having a low withstand voltage. Therefore, the high-frequency accelerator can be downsized. Also,
If at least one voltage measuring means is provided, the voltage of the acceleration gap can be measured, so that the high-frequency accelerator can be further miniaturized.

According to the high-frequency accelerator of claim 4, the loop antenna is provided so as to intersect at least one magnetic core in a chain shape, and the voltage measuring means for measuring the voltage of the acceleration gap is provided on the loop antenna. With the connection, the same operation and effect as those of the high-frequency accelerator according to claim 3 can be obtained.

According to the high frequency accelerator of the fifth aspect, the same operation and effect as those of the high frequency accelerator of the third or fourth aspect can be obtained, and the voltage of the acceleration gap can be reduced by connecting the voltage measuring means in series. It can measure accurately.

According to the annular accelerator of the sixth aspect, the operation control of the annular accelerator is facilitated by the provision of the high-frequency accelerator of the first, second, third, fourth or fifth aspect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a high-frequency accelerator 1 according to a first embodiment.

FIG. 2 is a diagram showing a high-frequency accelerator 1 according to a second embodiment.

FIG. 3 is a view showing a high-frequency accelerator 1 according to a third embodiment.

FIG. 4 is a diagram showing a high-frequency accelerator 1 according to a fourth embodiment.

FIG. 5 is a diagram showing a high-frequency accelerator 1 according to a fifth embodiment.

FIG. 6 is a diagram showing a high-frequency accelerator 1 according to a sixth embodiment.

FIG. 7 is a view showing a ring accelerator according to a seventh embodiment.

FIG. 8 is a diagram showing a conventional high-frequency accelerator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... High frequency accelerator, 2 ... Acceleration gap, 3 ... Central conductor, 4
... magnetic core, 5 ... loop antenna, 6 ... impedance adjusting means, 7 ... accelerating gap voltage measuring means, 8 ... high frequency power supply, 9 ... feeding loop antenna, 10 ... injector, 11
... deflecting electromagnet, 12 ... focusing electromagnet, 13 ... exiter, 14
... Differential amplifier, 15 ... Capacitor.

Claims (6)

[Claims] An annular magnetic body comprising: a central conductor having a passage for a charged particle beam formed therein and having an acceleration gap for inducing an acceleration electric field of the charged particle beam; and a plurality of annular magnetic cores. In a high-frequency accelerator in which a core is penetrated by the center conductor, at least one of a group of the magnetic cores including a plurality of the magnetic cores, a loop intersecting the magnetic cores of the group in a chain shape. A high-frequency accelerator, comprising: an antenna; and an impedance adjusting unit connected to the loop antenna. 2. An annular magnetic body, comprising: a central conductor having a passage for a charged particle beam formed therein and having an acceleration gap for inducing an acceleration electric field of the charged particle beam; and a plurality of annular magnetic cores. A high-frequency accelerator having a core penetrated by the center conductor, comprising: a loop antenna intersecting at least one of the magnetic cores in a chain shape; and an impedance adjusting means connected to the loop antenna. Accelerator. 3. A ring-shaped magnetic body comprising: a central conductor having a passage for a charged particle beam formed therein and having an acceleration gap for inducing an acceleration electric field of the charged particle beam; and a plurality of annular magnetic cores. In a high-frequency accelerator in which a core is penetrated by the center conductor, at least one of a group of the magnetic cores including a plurality of the magnetic cores, a loop intersecting the magnetic cores of the group in a chain shape. A high-frequency accelerator, comprising: an antenna; and voltage measuring means for measuring a voltage of the acceleration gap connected to the loop antenna. 4. An annular magnetic body, comprising: a central conductor having a passage for a charged particle beam formed therein and having an acceleration gap for inducing an accelerating electric field of the charged particle beam; and a plurality of annular magnetic cores. In a high-frequency accelerator having a core penetrated by the central conductor, a loop antenna crossing at least one of the magnetic cores in a chain shape is provided, and voltage measuring means for measuring a voltage of the acceleration gap connected to the loop antenna A high frequency accelerator comprising: 5. A high-frequency accelerator according to claim 3, wherein said voltage measuring means is connected in series. 6. An annular accelerator comprising the high-frequency accelerator according to claim 1, 2, 3, 4, or 5.