JPS58141000A - Cyclotron - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in cyclotrons used particularly in hospitals and the like.

First, a conventional cyclotron will be outlined with reference to FIG. 1, and then the present invention will be explained.

In FIG. 1, 2 is a resonator including a di-electrode 1.

a is a frequency compensation mechanism, for example, a capacitive frequency compensation mechanism; 4
・ is an exciter, and inside it there is a final stage vacuum tube 5 and a playback 1-
High frequency signal detector 9 and grid side high frequency signal detector 1
0, and the final stage vacuum tube is coupled to the resonator 2 via a coupling 6. 7 is a preamplifier, 8 is a signal processing system, and the signal processing system includes 11
11. A phase difference detector 11 receiving a high frequency signal from the high frequency signal detection HA9.10 and an oscillation)tH]2 are provided. The oscillator 12 has variable oscillation frequency and signal level depending on an external signal. ] 3 is a controller 1 that connects the phase difference detector 11 and the frequency compensation mechanism 3.
-I: I-le signal line.

In a cyclotron, 4 acceleration energies are applied to particles.
In a cyclotron, which generates a high frequency and high voltage on the di-electrode in order to generate high voltage, the system that generates such high frequency and high voltage is generally called a high frequency system. The high-frequency thread is roughly divided into resonator 2 including the de-electrode l, and resonator 2t.
It is comprised of a signal processing system 10 that processes a low-power high-frequency signal, including an exciter 4 that generates the injected high-frequency power and an oscillator 12.

Electrode] When generating a high frequency voltage at J2, high frequency high power is injected into the resonator 2;
Each part generates residual heat due to high frequency loss. These are removed by the cooling water flowing in the cooling pipe that has been pre-filled in the resonator, but when power is injected,
The temperature of the shaker changes.

This temperature change causes the shape of the resonator to change slightly, which in turn causes the resonant frequency of the resonator to vary.

In response to such frequency fluctuations, in the conventional cyclo1-ron, a mechanical Ii', l wave number compensation mechanism 3 is installed inside the resonator 2, and the phase difference detection visit 11J: recontrol signal 1i1131i< via the frequency Nlt fi′
A method has been used to compensate for fluctuations in Ii machine 1'flf3 so that the oscillation frequency always remains at a constant value.

The oscillation frequency of a high-frequency system is one of the parameters that determines the energy of particles accelerated by a cyclotron, and is essential for research purposes.

However, for this purpose, the resonator 2 of the cyclotron requires a mechanical frequency compensation mechanism 3, which is one of the factors that complicates the cyclotron body. In particular, this part is a part where a large high-frequency current flows, so the sliding contact part may burn out due to the high-frequency current.
Furthermore, since this is a part that penetrates the vacuum container, it is necessary to apply a f/it tight vacuum seal to the drive part to prevent vacuum leakage.

Furthermore, even when driving to generate a di-voltage, sophisticated driving techniques are required to find the resonance point by mechanically moving the frequency compensation mechanism minutely.

In a cyclotron whose purpose is to routinely produce radioactive iso-elements, it is no longer necessary to accurately determine the energy of accelerated particles. Therefore, even if a mechanical frequency compensation mechanism is installed, the performance
This would mean nothing, and would actually reduce reliability.
It only makes the operability worse.

The present invention was made to address these conventional problems, and its purpose is to improve reliability and operability by simplifying the main body of the cyclone 1-11. The objective is to realize a cyclotron that does not require technical operating personnel.

Next, the configuration of the ZAIK RJL Ron according to the present invention will be explained with reference to FIG. 2, but other components except for the important components of the present invention are the same as the conventional one explained in FIG. 1. Therefore, the same equipment as in FIG. 1 is designated by the same reference numeral 1, and the explanation thereof will be omitted, and only the different parts will be explained below.

The present invention is characterized in that the frequency compensation mechanism 3 installed in the conventional resonator 2 is omitted, and the phase difference detector 11 in the signal processing system 8 and the oscillator 12 are connected.

Next, the operation will be explained.

Whether the resonant frequency of the resonator 2 is tuned to the oscillator 120 frequency can be determined by using a phase difference detector to detect the phase difference between the high frequency signal on the plate side of the final stage vacuum tube of the exciter 4 and the high frequency signal on the grid side. 11. In the tuned state, the phase difference is approximately 180°. When power is injected into resonator 2, the resonant frequency of the resonator changes,
In the conventional method, the high frequency signal on the plate side of the final stage vacuum tube 5,
The resonant frequency of the resonator was corrected by the frequency compensation mechanism 3 so that the phase difference with the grid side high frequency signal was approximately iso°.

In contrast, in the present invention, the control signal line ]3' from the phase difference detector 11 is fed with a terminal that changes the oscillation frequency of the oscillator 12, so that the plate-side high-frequency signal of the final stage vacuum tube 5 and the grid The oscillation frequency of the oscillator 12 fluctuates so that the phase difference with the side high-frequency signal is always approximately 180 degrees (here, the frequency of the high-frequency system of the cyclotron can no longer be constant). .

However, in reality, large fluctuations occur only during the first three minutes or so after power is turned on. During this time, the resonator 2 will certainly undergo thermal deformation due to the loss of high-frequency current, and the resonance frequency will fluctuate greatly, so the oscillation frequency of the oscillator 2 will also fluctuate, but after 3 minutes or more, the resonator 2 will undergo thermal deformation stabilizes, and its fluctuation l] is determined by the fluctuation in the temperature of the cooling water that cools the resonator 2. For this reason, if the temperature of the cooling water is kept approximately constant by controlling it to within ±0.5 of the set temperature, for example, the frequency fluctuation can be controlled to a five-digit accuracy, as in the past. It can be suppressed.

Therefore, if more than 3 minutes have passed after powering on the high frequency system,
The frequency of the cyclotron's high-frequency system can also be considered constant, and does not affect the energy of the accelerated particles.

Note that a cyclotron may have two or more resonators, but if the present invention is applied to this, the frequencies that settle in each resonator will be different values, making it difficult to accelerate particles. Therefore, the present invention is effective only when there is only one resonator.

As detailed above, according to the present invention, the mechanical frequency compensation mechanism 3 is omitted from the cyclotron main body, and the frequency of the resonator is changed by following the electrical frequency of the oscillator. It solves the problems with conventional cyclotrons and contributes to improved reliability. In particular, the advanced technical operations and control system required when starting the de-electrode are simplified, resulting in labor savings and improved operability. Extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a control system diagram of a conventional Cyclo 1-ron. FIG. 2 shows a control system diagram of a cyclotron according to the present invention. l... De-electrode 2... Resonator 3... Frequency compensation mechanism 4... Exciter 5... Final stage vacuum tube 6...
Coupling 7... Preamplifier 8... Signal processing system 9... Plate side high frequency signal detector 10... Grid side high frequency signal detector 11... Phase difference detector 12... Oscillator 13 .13'...Control signal line Patent applicant Sumitomo Heavy Industries, Ltd.

Claims (1)

[Claims] In a high-frequency cyclotron consisting of a single resonator including a di-electrode, and a signal processing system that processes a low-power high-frequency signal including an exciter and total oscillator that generate high-frequency power to be injected into the resonant kl. In addition to removing the frequency compensation mechanism installed in the resonator, the phase difference detector and the oscillator in the signal processing system are connected to each other, so that the electrical frequency of the oscillator follows the frequency and wave number fluctuations of the resonator. A cyclotron that is characterized by a trembling structure.