JP3015669B2 - Charged particle accelerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charged particle accelerator, and more particularly to a phase control of a microwave supplied to an accelerator for accelerating charged particles.

[0002]

2. Description of the Related Art FIG.
LERATORS P.345 (NORTH-HOLLAND PUBL-ISHING COMPANY-A
MSTERDAM 1970) is a diagram showing a microwave phase control in a conventional charged particle accelerator, in which 1 is a microwave (AC voltage in a broader sense) oscillator, and 2 is the phase of the microwave. Is an amplifier for amplifying this microwave, and a klystron is used for the amplifier. 4 is an accelerating tube or cavity for accelerating charged particles, 6 is a dummy load for absorbing excess accelerating microwaves at the output point of the accelerating tube 4, 7 is a phase comparator,
103 is a coupler for branching the microwave from the oscillator 1;
A coupler 104 detects an electric field at an output point of the acceleration tube 4.

Next, the operation will be described. The microwave oscillated from the oscillator 1 enters the amplifier 3 through the phase shifter 2. Then, it is amplified by the amplifier 3 and enters the accelerating tube 4, forms an electric field in the accelerating tube 4, and accelerates the charged particle beam 9 by the formed electric field. When the state of the charged particle beam 9 is constant, when the phase difference between the phase of the microwave detected by the coupler 104 and the phase of the microwave detected by the coupler 103 is a predetermined reference value, The charged particle beam 9 is most effectively accelerated by the electric field. Coupler 1
04, phase comparator 7, phase shifter 2, amplifier 3, accelerating tube 4,
The feedback control loop formed by the combiner 104 is
The output of the combiner 103 and the output of the combiner 104 are automatically controlled such that a predetermined phase difference is maintained.

Here, the effective length of the high-frequency coaxial cable or waveguide from the oscillator 1 to the accelerator tube 4 changes due to a change in ambient temperature or the like, and the phase of the microwave entering the accelerator tube 4 changes. Phase of the electric field deviates from the optimum acceleration phase, and the acceleration performance may be deteriorated. At this time, the phase difference between the phase of the microwave detected by the coupler 103 and the phase of the microwave detected by the coupler 104 deviates from a predetermined value. ) Is output as an error signal, and the acceleration tube 4
The operation of optimizing the phase of the microwaves in the device and preventing a decrease in the acceleration performance is performed.

[0005]

The conventional charged particle accelerator as described above operates and operates as described above.
When the timing of the charged particles entering the accelerating tube 4 is unstable, there is a problem that the phase of the microwave in the accelerating tube 4 deviates from the optimal phase, and the beam acceleration performance is deteriorated. The electric field detected by the coupler 104 is a combined electric field of the electric field generated by the charged particle beam 9 and the electric field applied from the amplifier 3 to the accelerator tube 4 and propagated up to this point. However, if the number (current value) of charged particles entering the accelerating tube 4 changes, the phase of the electric field detected by the coupler 104 changes, and the change is supplied from the amplifier 3 to the accelerating tube 4 due to this change. There is a problem that the phase of the microwave to be controlled is controlled to a point shifted from the optimum phase.

The present invention has been made to solve such a problem, and maintains an appropriate phase even when the timing of charged particles entering the acceleration tube 4 and the number (current value) of charged particles are unstable. It is another object of the present invention to provide a charged particle accelerator in which the beam acceleration performance does not deteriorate.

[0007]

A charged particle accelerator according to the present invention has a phase detection cavity placed upstream of an acceleration tube or an acceleration cavity for accelerating charged particles, and a phase comparator for comparing the phases of microwaves. A phase shifter that changes the phase was combined with a phase shifter.

That is, an accelerating tube for accelerating charged particles, a phase detecting cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the accelerating tube,
An oscillator for generating an AC voltage for accelerating the charged particles in the accelerating tube, a phase shifter for changing a phase of an AC voltage of an output of the oscillator, and an output of the phase shifter for amplifying the output of the charged particle An amplifier applied to an input point, a coupler coupled to an output of the amplifier to generate an AC voltage representing the output, and a phase difference between the AC voltage detected by the phase detecting cavity and the AC voltage detected by the coupler. A phase comparator for detecting a deviation amount from a predetermined reference phase difference, a means for performing a feedback control of the phase shifter so that the deviation amount detected by the phase comparator is used as an error signal, and the error signal is set to zero. It is characterized by having.

[0009] Further, the present invention is characterized in that charged particles are accelerated in a second accelerating tube provided in addition to the accelerating tube by the output of the amplifier.

An acceleration tube for accelerating charged particles, an input point phase detection cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the acceleration tube, and a charged particle output of the acceleration tube An output point phase detection cavity for detecting an AC voltage representing an electric field formed by charged particles output at a point, an oscillator for generating an AC voltage for accelerating the charged particles in the accelerator tube, and a phase of an AC voltage for the output of the oscillator. A phase shifter to be changed, an amplifier that amplifies the output of the phase shifter and adds it to the charged particle input point of the accelerator tube, and detects the AC voltage detected by the input point phase detection cavity and the output point phase detection cavity. A phase comparator for detecting an amount of deviation between a phase difference between the AC voltage and a predetermined reference phase difference, and using the amount of deviation detected by the phase comparator as an error signal; Characterized by comprising a means for feedback controlling the phase shifter to.

A first accelerating tube for accelerating the charged particles;
A phase detection cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the first acceleration tube; a second acceleration tube for accelerating the charged particles; the first and second accelerations An oscillator for generating an AC voltage for accelerating the charged particles in the tube, a first phase shifter for changing the phase of the AC voltage of the output of the oscillator, and amplifying the output of the first phase shifter to produce the first phase shifter A first amplifier coupled to the charged particle input of the accelerator tube, a first combiner coupled to the output of the first amplifier to generate an AC voltage representative of the output, a phase of the AC voltage at the output of the oscillator A second phase shifter, which amplifies the output of the second phase shifter and adds the amplified output to the charged particle input point of the second accelerator tube. A second combination for combining and producing an AC voltage representative of its output A coaxial switch for switching and outputting the output of the phase detection cavity, and a phase difference between one output of the coaxial switch and the AC voltage detected by the first coupler and a predetermined reference phase difference. First to detect the amount of deviation between
Means for controlling the first phase shifter to perform feedback control such that the error detected by the first phase comparator is used as an error signal, and the error signal to be zero; And a second phase comparator for detecting a deviation between a phase difference between the output of the second coupler and the AC voltage detected by the second coupler and the reference phase difference. The second phase comparator detects the deviation. The obtained deviation amount is used as an error signal, and a means for feedback-controlling the second phase shifter so as to make the error signal zero is provided.

Further, a first accelerating tube for accelerating charged particles, a phase detecting cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the first accelerating tube, and a charged particle A second accelerating tube for accelerating, an oscillator for generating an AC voltage for accelerating the charged particles in the first and second accelerating tubes, a first phase shifter for changing a phase of the AC voltage output from the oscillator; A first amplifier for amplifying the output of the first phase shifter and applying it to the charged particle input point of the first accelerator, generating an ac voltage coupled to the output of the first amplifier and representing the output; A first coupler,
A second phase shifter for changing the phase of the AC voltage at the output of the oscillator, a second amplifier for amplifying the output of the second phase shifter and applying the amplified output to the charged particle input point of the second accelerator tube; A second coupler for coupling to the output of the second amplifier to generate an AC voltage representing the output, a coaxial switch for switching and outputting the output of the first coupler or the output of the second coupler. Device, a phase comparator for detecting a deviation amount between a phase difference between the output of the coaxial switch and the AC voltage detected by the phase detection cavity and a predetermined reference phase difference, which is detected by the phase comparator. A deviation amount is used as an error signal, and a means for feedback-controlling the first or second phase shifter so as to make the error signal zero is provided.

[0013]

The charged particle accelerator according to the present invention includes a phase detection cavity and a coupler coupled to the output of the amplifier and generating an AC voltage representing the output, so that the phase of the charged particles detected by the phase detection cavity is reduced. On the other hand, the phase of the microwave supplied to the accelerating tube is adjusted to optimize the accelerating phase in the accelerating tube. Since the phase detection cavity is not affected by the microwave applied from the amplifier, only the electric field formed by the charged particles can be detected.

Further, by employing a configuration in which charged particles are accelerated in the second acceleration tube, the phase of the microwave is adjusted while using only one phase shifter and one amplifier.
It is possible to optimize the acceleration phase in the acceleration tube.

Further, by providing the input point phase detection cavity and the output point phase detection cavity, the phase of the microwave is adjusted without having to split the microwave entering the acceleration tube by the coupler, and the acceleration phase in the acceleration tube is adjusted. Can be optimized.

Further, even in the case of a charged particle accelerator having a plurality of acceleration tubes, the acceleration phase in the acceleration tube can always be optimized, and the acceleration performance can always be kept at the maximum.

Further, in a charged particle accelerator having a plurality of acceleration intervals, the phase comparator can be made one and the acceleration phase in the acceleration tube can always be optimized, so that the acceleration performance can always be kept at the highest state.

[0018]

【Example】

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram for explaining a charged particle accelerator according to Embodiment 1 of the present invention. In FIG. 1, the same reference numerals as those in FIG. 6 denote the same or corresponding parts, and 8 denotes a charged particle beam 9 formed. A phase detection cavity for detecting a microwave voltage to be detected, and a microwave voltage to be detected is used.
Called. Reference numeral 10 denotes a coupler.

The optimum phase of acceleration in the acceleration tube 4 is determined by determining the phase difference between the phase of the microwave voltage detected by the phase detecting cavity 8 and the phase of the microwave voltage detected by the coupler 10 to a predetermined reference value (this reference value). The value becomes a constant value if the conditions are kept constant, and can be measured in advance.
When the acceleration value reaches the first reference value), the acceleration performance of the acceleration tube 4 becomes the highest. Phase comparator 7, phase shifter 2,
A feedback loop constituted by the amplifier 3, the combiner 10, and the phase comparator 7 is automatically controlled so that the output phase of the combiner 10 maintains a phase difference of a predetermined reference value with respect to the output phase of the phase detection cavity 8. .

That is, the first reference value is set in the phase comparator 7, and the phase difference between the phase detected by the phase detecting cavity 8 and the phase detected by the coupler 10 is calculated by the first reference value.
When the reference value does not become the reference value, the difference between the two phase differences is used as an error signal, and the feedback loop operates so as to make this error signal zero.

Embodiment 2 FIG. FIG. 2 is a block diagram for explaining a charged particle accelerator according to Embodiment 2 of the present invention. In the figure, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, 81 denotes an input point phase detection cavity, 82 Is an output point phase detection cavity. In the above-described first embodiment shown in FIG. 1, the phase of the microwave detected by the phase detection cavity 8 is
Although the microwaves entering the acceleration tube 4 are branched by the coupler 10 and the phases are compared, instead of the microwaves branched by the coupler 10, the phases arranged before and after the acceleration tube 4 as shown in FIG. The phases of the microwaves induced in the detection cavities 81 and 82 may be compared with each other.

That is, the input point phase detection cavity 81 detects the electric field due to the charged particle beam 9 before the influence of the microwave electric field applied to the accelerator tube 4, and the output point phase detection cavity 82 detects the charged state after the acceleration. By detecting the combined electric field of the electric field by the particle beam and the electric field applied from the amplifier 3, the two phase detection cavities 81 are provided under the condition that the output amplitude of the amplifier 3 is kept constant. , 8
The fact that the phase difference between the two detected phases is kept at a predetermined reference value (tentatively referred to as a second reference value) means the optimum acceleration phase.

Embodiment 3 FIG. FIG. 3 is a block diagram for explaining a charged particle accelerator according to Embodiment 3 of the present invention. In the drawings, the same reference numerals as those in FIGS. 1 and 2 denote the same or corresponding parts, 11 denotes a coaxial switch, 41 and 42 are acceleration tubes, respectively, and 101 and 102 are couplers, respectively. FIG.
When there are a plurality of acceleration tubes, the microwaves induced in the phase detection cavity 8 are switched by the coaxial switch 11, and the phase of the microwaves entering the acceleration tubes 41 and 42 in the phase comparator 7 of each accelerator as shown in FIG. The same effect as in the first embodiment can be obtained by comparing

Embodiment 4 FIG. FIG. 4 is a block diagram for explaining a charged particle accelerator according to Embodiment 4 of the present invention. In the drawings, the same reference numerals as those in FIGS. 1 to 3 denote the same or corresponding parts. The charged particle accelerator according to the fourth embodiment has a single phase comparator 7, and when there are a plurality of acceleration tubes, the phase of the microwave induced in the phase detection cavity 8 is controlled by the coaxial switch 11 for each phase. The microwaves that enter the acceleration tubes 41 and 42 are switched, and the phase is compared by the phase comparator 7.

Embodiment 5 FIG. FIG. 5 is a block diagram for explaining a charged particle accelerator according to Embodiment 5 of the present invention. In the drawing, the same reference numerals as those in FIGS. 1 to 4 denote the same or corresponding parts. In the charged particle accelerator according to the fifth embodiment, one amplifier 3 supplies microwaves to a plurality of acceleration tubes 41 and 42, and a waveguide or a coaxial line from the amplifier 3 to each of the acceleration tubes 41 and 42 is supplied. When the effective lengths are equal, the same effect can be obtained by comparing only the phase of the microwaves entering one of the accelerating tubes 41 with the phase of the microwaves induced in the phase detection cavity 8. It is.

In the above-described third to fifth embodiments, two accelerator tubes 41 and 42 are described as an example of a case where there are a plurality of accelerator tubes. However, there are two or more accelerator tubes. Needless to say, the same can be implemented.

[0027]

As described above, the charged particle accelerator according to the present invention has a phase detection cavity placed upstream of an acceleration tube or an acceleration cavity for accelerating charged particles and a phase comparator for comparing the phases of microwaves. By combining the phase shifter and the phase shifter that changes the phase, the acceleration phase in the acceleration tube can always be optimized, and there is an effect that the acceleration performance can always be kept at the highest state.

Further, by employing a configuration in which charged particles are accelerated in the second accelerating tube, the phase of the microwave is adjusted while using only one phase shifter and one amplifier.
It is possible to optimize the acceleration phase in the acceleration tube.

Further, by providing the input point phase detection cavity and the output point phase detection cavity, it is possible to adjust the phase of the microwave without branching the microwave entering the acceleration tube by the coupler, and to increase the acceleration phase in the acceleration tube. Can be optimized.

Even in a charged particle accelerator having a plurality of accelerating tubes, the acceleration phase in the accelerating tubes can always be optimized, and the accelerating performance can always be kept at the highest level.

Further, in the case of a plurality of charged particle accelerators during the acceleration, there is an advantage that the acceleration phase in the acceleration tube is always optimized by using one phase comparator, and the acceleration performance can always be kept at the highest state. is there.

[Brief description of the drawings]

FIG. 1 is a block diagram for explaining a first embodiment of the present invention.

FIG. 2 is a block diagram for explaining a second embodiment of the present invention.

FIG. 3 is a block diagram for explaining a third embodiment of the present invention;

FIG. 4 is a block diagram for explaining a fourth embodiment of the present invention.

FIG. 5 is a block diagram for explaining Embodiment 5 of the present invention.

FIG. 6 is a block diagram for explaining a conventional charged particle accelerator.

[Explanation of symbols]

1 oscillator, 2 phase shifter, 3 amplifier, 4 accelerator tube, 6
Dummy load, 7 phase comparator, 8 phase detection cavity,
9 charged particle beam, 10 coupler, 11 coaxial switch, 41, 42 accelerator tube, 81 input point phase detection cavity,
82 output point phase detection cavity, 101, 102, 103,
104 combiner.

Claims (5)

(57) [Claims] An acceleration tube for accelerating charged particles, a phase detection cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the acceleration tube, and accelerating the charged particles in the acceleration tube An oscillator that generates an alternating voltage that changes the phase of an alternating voltage of the output of the oscillator; an amplifier that amplifies the output of the phase shifter and adds the output to the charged particle input point of the accelerator tube; A coupler coupled to the output to generate an AC voltage representative of the output; and a phase difference between the AC voltage detected by the phase detection cavity and the AC voltage detected by the coupler and a predetermined reference phase difference. A phase comparator for detecting the amount of deviation; and a means for feedback-controlling the phase shifter so that the amount of deviation detected by the phase comparator is used as an error signal, and the error signal is set to zero. A charged particle accelerator. 2. The charged particle accelerator according to claim 1, wherein the charged particles are accelerated in a second acceleration tube provided in addition to the acceleration tube by an output of the amplifier. 3. An acceleration tube for accelerating charged particles, an input point phase detection cavity for detecting an AC voltage representing an electric field formed by charged particles inputted at a charged particle input point of the acceleration tube, a charged particle output of the acceleration tube An output point phase detection cavity for detecting an AC voltage representing an electric field formed by charged particles output at a point; an oscillator for generating an AC voltage for accelerating the charged particles in the accelerator tube; A phase shifter for changing, an amplifier for amplifying the output of the phase shifter and applying it to the charged particle input point of the accelerator tube, and detecting the AC voltage detected by the input point phase detection cavity and the output point phase detection cavity. A phase comparator for detecting a deviation between a phase difference between the AC voltage and a predetermined reference phase difference; a deviation detected by the phase comparator as an error signal; Means for feedback controlling the phase shifter to the charged particle acceleration apparatus comprising the. 4. A first accelerating tube for accelerating charged particles, a phase detecting cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the first accelerating tube, A second accelerating tube for accelerating, an oscillator for generating an AC voltage for accelerating the charged particles in the first and second accelerating tubes, a first phase shifter for changing a phase of an AC voltage output from the oscillator, A first amplifier for amplifying the output of the first phase shifter and applying it to the charged particle input point of the first accelerating tube; generating an AC voltage coupled to the output of the first amplifier and representing the output; A second phase shifter for changing the phase of the AC voltage of the output of the oscillator, and an input of the charged particle input of the second accelerator tube by amplifying the output of the second phase shifter. A second amplifier to add to the point, the output of this second amplifier A second coupler for generating an AC voltage representing the output of the second phase detector, a coaxial switch for switching and outputting the output of the phase detection cavity, and detecting one output of the coaxial switch and the first coupler. A first phase comparator for detecting a deviation between a phase difference between the detected AC voltage and a predetermined reference phase difference; a deviation detected by the first phase comparator as an error signal; Means for feedback-controlling the first phase shifter so as to make the signal zero; a phase difference between the other output of the coaxial switch and the AC voltage detected by the second coupler; A second phase comparator for detecting an amount of deviation from the phase difference; an error signal using the amount of deviation detected by the second phase comparator; and a second phase shifter for setting the error signal to zero. Means for feedback control of Child accelerator. 5. A first accelerating tube for accelerating charged particles, a phase detecting cavity for detecting an AC voltage representing an electric field formed by charged particles input at a charged particle input point of the first accelerating tube, A second accelerating tube for accelerating, an oscillator for generating an AC voltage for accelerating the charged particles in the first and second accelerating tubes, a first phase shifter for changing a phase of an AC voltage output from the oscillator, A first amplifier for amplifying the output of the first phase shifter and applying it to the charged particle input point of the first accelerating tube; generating an AC voltage coupled to the output of the first amplifier and representing the output; A second phase shifter for changing the phase of the AC voltage of the output of the oscillator, and an input of the charged particle input of the second accelerator tube by amplifying the output of the second phase shifter. A second amplifier to add to the point, the output of this second amplifier A second coupler for generating an AC voltage representing the output of the second coupler, a coaxial switch for switching the output of the first coupler or the output of the second coupler for output, and an output of the coaxial switch. And a phase comparator for detecting a deviation between a phase difference between the AC voltage detected by the phase detection cavity and a predetermined reference phase difference.The deviation detected by the phase comparator is used as an error signal. Means for feedback-controlling the first or second phase shifter so that the error signal is reduced to zero.