JP7079489B2 - How to set up an accelerated electric field in an RF cavity at high speed - Google Patents
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本発明は、一台のＲＦ源を用いて、二つの特性が異なるＲＦ空洞を駆動するＲＦ電力とＲＦ電力の出力周波数であるＲＦ周波数をそれぞれの所定の値に高速で到達させ、ＲＦ空洞に所定の電場を形成する、「ＲＦ空洞に加速電場を高速で立ち上げる方法」に関する。 In the present invention, using one RF source, the RF frequency that drives an RF cavity with two different characteristics and the RF frequency, which is the output frequency of the RF power, reach their respective predetermined values at high speed, and the RF cavity is reached. The present invention relates to "a method of setting up an accelerated electric field in an RF cavity at high speed" that forms a predetermined electric field.
一．ＢＮＣＴ陽子加速器におけるＲＦ空洞について
特許文献１に示すように、中性子捕捉療法（ＢＮＣＴ）に用いる高周波加速器（ここでは、ＢＮＣＴ陽子加速器）におけるＲＦ空洞はＲＦＱ（Ｒａｄｉｏ Ｆｒｅｑｕｅｎｃｙ Ｑｕａｄｒｕｐｏｌｅ Ｌｉｎａｃ：高周波４重極型リニアック）空洞と、ＤＴＬ（Ｄｒｉｆｔ Ｔｕｂｅ Ｌｉｎａｃ：ドリフトチューブリニアック）空洞の二種類のＲＦ空洞で構成され、その二つのＲＦ空洞は構成と特性が大きく異なっている。
one. RF cavities in BNCT proton accelerators As shown in
構成面では、ＲＦＱ空洞とＤＬＴ空洞（以下、単に「それらＲＦ空洞」ともいう）に備えられている共振周波数調整システムが異なっている。ＲＦＱ空洞の共振周波数調整システムは冷却水循環システムを用いて水温で共振周波数を調整する。一方、ＤＴＬ空洞の共振周波数調整システムは冷却水循環システムと可動式機械チューナーを用いて共振周波数を調整する。 In terms of composition, the resonance frequency adjustment system provided in the RFQ cavity and the DLT cavity (hereinafter, also simply referred to as “these RF cavities”) is different. The resonance frequency adjustment system of the RFQ cavity adjusts the resonance frequency by the water temperature using the cooling water circulation system. On the other hand, the resonance frequency adjustment system of the DTL cavity adjusts the resonance frequency by using a cooling water circulation system and a movable mechanical tuner.
他方、ＲＦＱ空洞とＤＬＴ空洞の高周波の特性面では、主に次のような違いがある。
（１）
二つのＲＦ空洞は、負荷品質係数（ｌｏａｄｅｄ ｑｕａｌｉｔｙ ｆａｃｔｏｒ、以下「ＱＬ値」という）が大きく異なっている。ＱＬ値が大きいほうが、ＲＦ空洞の周波数帯域は狭くて、消耗電力は少ない。
ＲＦＱ空洞のＱＬ値は約３５００で、ＤＴＬ空洞のＱＬ値は約１６０００でＲＦＱ空洞のＱＬ値の約５倍である。またＱＬ値が大きく異なっていることから、ＱＬ値に関連するすべての特性が大きく異なっている。例えば、ＲＦ空洞自身の消費電力の割合、ＲＦ空洞のＲＦ立上げ時の充填時間（ｆｉｌｌｉｎｇ ｔｉｍｅ）などが大きく異なっている。
（２）
二つのＲＦ空洞は、ビームに対しての機能と負荷も大きく異なっている。
ＲＦＱ空洞の加速電場はビームを加速しながらｂｕｎｃｈｉｎｇする。ＤＴＬ空洞の加速電場はビームを加速するだけである。
さらに、二つのＲＦ空洞は、ビームに与えるエネルギー及びビーム負荷が異なっている。ＲＦＱ空洞はビームを３ＭｅＶまで加速し、ピーク電流５０ｍＡの場合のビーム負荷は１５０ｋＷである。一方、ＤＴＬ空洞はビームを更に８ＭｅＶまで加速するので、５０ｍＡの場合にビーム負荷は２５０ｋＷとなる。
On the other hand, there are mainly the following differences in the high frequency characteristics of the RFQ cavity and the DLT cavity.
(1)
The two RF cavities differ greatly in the loaded quality factor (hereinafter referred to as " QL value"). The larger the QL value, the narrower the frequency band of the RF cavity and the smaller the power consumption.
The QL value of the RFQ cavity is about 3500, and the QL value of the DTL cavity is about 16000, which is about 5 times the QL value of the RFQ cavity. Moreover, since the QL values are significantly different, all the characteristics related to the QL values are significantly different. For example, the ratio of the power consumption of the RF cavity itself, the filling time at the time of RF start-up of the RF cavity, and the like are significantly different.
(2)
The two RF cavities also differ significantly in function and load on the beam.
The accelerated electric field in the RFQ cavity bunches while accelerating the beam. The accelerated electric field in the DTL cavity only accelerates the beam.
Furthermore, the two RF cavities differ in the energy and beam load applied to the beam. The RFQ cavity accelerates the beam to 3 MeV and the beam load at a peak current of 50 mA is 150 kW. On the other hand, the DTL cavity further accelerates the beam to 8 MeV, so that the beam load is 250 kW at 50 mA.
二．ＲＦＱ空洞とＤＴＬ空洞を駆動するＲＦ源について
特性の異なる二つのＲＦ空洞であるＦＱ空洞とＤＬＴ空洞を駆動するＲＦ源は、２台の独立なＲＦ源を用いる場合と、一台のＲＦ源で行う場合がある。それぞれの利点と欠点を表１にまとめた。
two. About the RF source that drives the RFQ cavity and the DTL cavity The RF source that drives the FQ cavity and the DLT cavity, which are two RF cavities with different characteristics, can be used with two independent RF sources or with one RF source. May be done. Table 1 summarizes the advantages and disadvantages of each.
通常の加速器研究開発では、複数の特性が異なるＲＦ空洞は、各々独立したＲＦ源で駆動することが一般的である。特に、ＲＦＱ空洞とＤＴＬ空洞の特性は大きく異なっていることから、２台の独立したＲＦ源が必要であるということが今までの常識的な考えであった。 In ordinary accelerator research and development, it is common that multiple RF cavities with different characteristics are driven by independent RF sources. In particular, since the characteristics of the RFQ cavity and the DTL cavity are significantly different, it has been a common sense until now that two independent RF sources are required.
しかし、ＢＮＣＴ陽子加速器は、大型科学研究施設用ではなく、将来的に多くの医療機関に普及することを目指しているため、できるだけ低コストで、高性能であることが望まれる。 However, since the BNCT proton accelerator is not for large-scale scientific research facilities and aims to be widely used in many medical institutions in the future, it is desired that the cost is as low as possible and the performance is high.
従って、低コストと高性能の両立は重要課題で、ＢＮＣＴ陽子加速器では敢えて一台のＲＦ源で二つのＲＦ空洞を駆動する構成を採用し、医療用高周波加速器としての実現性を最優先にすることにした。 Therefore, achieving both low cost and high performance is an important issue, and the BNCT proton accelerator dares to adopt a configuration in which two RF cavities are driven by one RF source, and the feasibility as a medical high-frequency accelerator is given top priority. It was to be.
三．加速電場立ち上げ制御について
一台のＲＦ源で、二つのＲＦ空洞に、ＲＦ電源をＲＦ周波数で供給して加速電場を形成する場合に、ＬＬＲＦ制御に多くの課題がある。特に、加速電場立ち上げ時の制御は非常に重要で、医療利用できる高周波加速器の要求を満たす性能を実現しなければならない。
three. Accelerated electric field start-up control There are many problems in LLRF control when an RF power source is supplied to two RF cavities at an RF frequency to form an accelerated electric field with one RF source. In particular, control at the start of the accelerating electric field is very important, and it is necessary to realize the performance that meets the requirements of high-frequency accelerators that can be used for medical treatment.
医療用高周波加速器の加速電場立ち上げについて、基本的な要求は二つある。
一つは、加速電場立ち上げの際、それらのＲＦ空洞からの反射電力を同時にできるだけ最小に抑えなければならないことである。
そうしないと、どちらの一方から大きな反射電力があった場合に、設備の重故障を避けるための自動インターロック保護システムが作動し、立ち上げ失敗となり、途中で終了してしまうためである。
There are two basic requirements for setting up an accelerated electric field for medical high-frequency accelerators.
One is that the reflected power from those RF cavities must be minimized at the same time when the accelerated electric field is set up.
Otherwise, if there is a large amount of reflected power from either side, the automatic interlock protection system for avoiding serious equipment failure will operate, resulting in startup failure and termination in the middle.
もう一つは、加速電場立ち上げの所要時間をできるだけ短くしなければならないことである。目標は５分間以内である。
そうしないと、治療中に加速器運転再開が必要な場合に、患者の待ち時間が長くなって、医療用治療装置としての条件を満たさなくなる。
The other is that the time required to set up the accelerated electric field must be as short as possible. The goal is within 5 minutes.
Otherwise, if the accelerator needs to be restarted during treatment, the patient's waiting time will be long and the condition as a medical treatment device will not be satisfied.
一方、ＲＦＱ空洞とＤＴＬ空洞の特性は大きく異なっているから、加速電場立ち上げの際に、それらＲＦ空洞の温度と共振周波数は、時間の経過に伴い、それぞれ異なる変化を示し、一般的なＬＬＲＦの手法では、上記の二つの要求を満たすのは非常に困難である。
従って、加速電場立ち上げの制御について、一台のＲＦ源で二つのＲＦ空洞を駆動する場合、二台の場合よりも、より正確かつ精密な制御システムの開発が必要である。
On the other hand, since the characteristics of the RFQ cavity and the DTL cavity are significantly different, the temperature and resonance frequency of the RF cavity show different changes with the passage of time when the accelerated electric field is started, and it is a general LLRF. With this method, it is very difficult to meet the above two requirements.
Therefore, regarding the control of the acceleration electric field start-up, when driving two RF cavities with one RF source, it is necessary to develop a more accurate and precise control system than in the case of two units.
そこで、本発明は、一台のＲＦ源を用いて、二つの特性が異なるＲＦ空洞を駆動するＲＦ電力とＲＦ電力の出力周波数であるＲＦ周波数をそれぞれの所定の値に高速で到達させ、ＲＦ空洞に所定の電場を形成する、「ＲＦ空洞に加速電場を高速で立ち上げる方法」を提供することを目的とする。 Therefore, in the present invention, using one RF source, the RF frequency that drives the RF cavity having two different characteristics and the RF frequency, which is the output frequency of the RF power, reach their respective predetermined values at high speed, and RF. It is an object of the present invention to provide "a method of setting up an accelerated electric field in an RF cavity at high speed" in which a predetermined electric field is formed in the cavity.
（１）
第一ＲＦ空洞及びチューナーを有する第二ＲＦ空洞と、特性が異なる前記第一ＲＦ空洞及び前記第二ＲＦ空洞に、駆動電力であるＲＦ電力をＲＦ周波数で出力、供給することで、前記第一ＲＦ空洞及び前記第二ＲＦ空洞に加速電場を形成させる一台のＲＦ源を備える高周波加速器において、
前記第一ＲＦ空洞及び前記第二ＲＦ空洞の起動時に、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の両方の共振周波数を検出し、
前記ＲＦ源から前記第一ＲＦ空洞及び前記第二ＲＦ空洞に出力する前記ＲＦ電力の前記ＲＦ周波数を、前記検出にて得た前記共振周波数のいずれか一方に一致させるよう変調し、変調した周波数である変調周波数で、前記第一ＲＦ空洞及び前記第二ＲＦ空洞に前記ＲＦ電力を出力するとともに、
前記チューナーを制御して、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の共振周波数を同じにすることで、
前記第一ＲＦ空洞及び前記第二ＲＦ空洞の共振周波数と前記ＲＦ電力の前記ＲＦ周波数を同じにし、
前記第一ＲＦ空洞及び前記第二ＲＦ空洞からの反射電力を低減させることで、
前記ＲＦ源から出力され、前記第一ＲＦ空洞及び前記第二ＲＦ空洞を駆動する前記ＲＦ電力及び前記ＲＦ周波数を所定値に短時間で到達させ、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の加速電場を高速に所定の電場に形成することを特徴とする
ＲＦ空洞に加速電場を高速で立ち上げ方法。
（２）
前記第一ＲＦ空洞がＲＦＱ空洞で、前記第二ＲＦ空洞がＤＴＬ空洞であることを特徴とする
（１）に記載のＲＦ空洞に加速電場を高速で立ち上げ方法。
（３）
前記共振周波数の検出を、ＱＬ値が高い前記ＲＦ空洞から行うことを特徴とする（１）に記載のＲＦ空洞に加速電場を高速で立ち上げ方法。
（４）
前記加速電場高速立ち上げ方法が、ＢＮＣＴ陽子加速器に利用される場合においては、前記ＱＬ値が高いＲＦ空洞が、前記ＤＴＬ空洞であることを特徴とする（３）に記載のＲＦ空洞に加速電場を高速で立ち上げ方法。
とした。
(1)
By outputting and supplying RF power, which is a driving power, to the first RF cavity and the second RF cavity having a tuner, and the first RF cavity and the second RF cavity having different characteristics at an RF frequency, the first RF cavity and the second RF cavity have different characteristics. In a high frequency accelerator equipped with one RF source for forming an accelerating electric field in the RF cavity and the second RF cavity.
At the time of activation of the first RF cavity and the second RF cavity, the resonance frequencies of both the first RF cavity and the second RF cavity are detected.
The RF frequency of the RF power output from the RF source to the first RF cavity and the second RF cavity is modulated and modulated so as to match one of the resonance frequencies obtained by the detection. At the modulation frequency of, the RF power is output to the first RF cavity and the second RF cavity, and the RF power is output.
By controlling the tuner to make the resonance frequencies of the first RF cavity and the second RF cavity the same,
The resonance frequency of the first RF cavity and the second RF cavity and the RF frequency of the RF power are made the same.
By reducing the reflected power from the first RF cavity and the second RF cavity,
The RF power and the RF frequency output from the RF source and driving the first RF cavity and the second RF cavity are brought to a predetermined value in a short time, and the first RF cavity and the second RF cavity are formed. A method of setting up an accelerating electric field at high speed in an RF cavity, which is characterized by forming an accelerating electric field into a predetermined electric field at high speed.
(2)
The method for setting up an accelerating electric field at high speed in the RF cavity according to (1), wherein the first RF cavity is an RFQ cavity and the second RF cavity is a DTL cavity.
(3)
The method for raising an accelerating electric field at high speed in the RF cavity according to (1), wherein the resonance frequency is detected from the RF cavity having a high QL value.
(4)
When the accelerated electric field high-speed start-up method is used for the BNCT proton accelerator, the RF cavity having a high QL value is accelerated to the RF cavity according to (3). How to set up an electric field at high speed.
And said.
本発明は、上記構成であるので、次の効果を奏する。
本発明の方法では
（一）従来法に比して、４－１０倍も短く（３－５分に短縮）、加速電場を高速に立ち上げることが可能となる。
（二）ＲＦＱ空洞とＤＴＬ空洞など異なる複数の型のＲＦ空洞を有する高周波加速器に対し、一台のＲＦ源でＲＦ電力供給が可能になる。
（三）加速電場立ち上げの時、ＲＦＱ空洞とＤＴＬ空洞の共振周波数とＲＦ源の出力ＲＦ周波数は同じであり、それらＲＦ空洞からの反射電力を極めて少ないレベルに維持することができる。その結果、高周波加速器の運転維持は容易になるし、高周波加速システム全体（ＲＦ源、ＲＦ ｄｕｍｍｙ ｌｏａｄなど）に対する負荷は最少となり、機器故障確率も低減するので、高周波加速器システム全体は長寿命になる。
（四）加速電場立ち上げの時、入口水温は一定でも高速で立ち上げが可能となる。
（五）ＲＦ源とＬＬＲＦ制御はそれぞれ一台で、建設費用は約半分になり、敷地もコンパクトになり、高周波加速器は小型化できる。
との効果がある。
Since the present invention has the above configuration, it has the following effects.
The method of the present invention is (1) shorter than the conventional method by 4 to 10 times (shortened to 3-5 minutes), and the accelerating electric field can be started up at high speed.
(2) RF power can be supplied from one RF source to a high frequency accelerator having a plurality of different types of RF cavities such as RFQ cavities and DTL cavities.
(3) At the time of starting the accelerated electric field, the resonance frequency of the RFQ cavity and the DTL cavity and the output RF frequency of the RF source are the same, and the reflected power from those RF cavities can be maintained at an extremely low level. As a result, it becomes easier to maintain the operation of the high-frequency accelerator, the load on the entire high-frequency acceleration system (RF source, RF duty load, etc.) is minimized, and the probability of equipment failure is also reduced, so that the entire high-frequency accelerator system has a long life. ..
(4) When the accelerated electric field is started up, it can be started up at high speed even if the inlet water temperature is constant.
(5) With one RF source and one LLRF control, the construction cost will be halved, the site will be compact, and the high-frequency accelerator can be miniaturized.
There is an effect with.
以下、添付の図面を参照し、本発明の実施の形態について、従来技術と対比しながら、詳細に説明する。なお、本発明は下記形態例に限定されるものではない。 Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, in comparison with the prior art. The present invention is not limited to the following examples.
・従来技術
加速電場を所定の値に立ち上げる従来技術は、図１（１）に示すように、「ＲＦ空洞の共振周波数を加速器運転周波数ｆ０に維持しながら、徐々にＲＦ源の出力ＲＦ電力を上げる」方法であった。
なお、図１の記号の意味は次の通りである。
ｆ０：加速器運転周波数
ｆ１：ＲＦＱ共振周波数
ｆ２：ＤＴＬ共振周波数
ｆｒｆ：ＲＦ源の出力ＲＦ周波数
-Prior technique As shown in Fig. 1 (1), the conventional technique for raising the accelerating electric field to a predetermined value is "the output RF of the RF source gradually while maintaining the resonance frequency of the RF cavity at the accelerator operating frequency f0 . It was a method of "increasing power".
The meanings of the symbols in FIG. 1 are as follows.
f 0 : Accelerator operating frequency f 1 : RFQ resonance frequency f 2 : DTL resonance frequency frf : RF source output RF frequency
従来技術では、ＲＦＱ空洞３及びＤＴＬ空洞４の立ち上げの際は、加速器運転周波数ｆ０を持つ一台のＲＦ源２から、徐々に、ＲＦ源の出力ＲＦ電力を上げて、それらＲＦ空洞に与える。そうすると、それらＲＦ空洞が昇温するので、それらＲＦ空洞に付いている共振周波数調整システムを使って、それらＲＦ空洞のＲＦＱ共振周波数ｆ１及びＤＴＬ共振周波数ｆ２を、共に、加速器運転周波数ｆ０に近づけていく。
In the prior art, when the
ＲＦＱ空洞３は冷却水６の入口水温を調整することで、ＲＦＱ共振周波数ｆ１を加速器運転周波数ｆ０に維持する。一方、ＤＴＬ空洞４は冷却水６の入口水温調整とチューナー５の調整で、ＤＴＬ共振周波数ｆ２を加速器運転周波数ｆ０に維持する。
The
このような調整を行うことで、それらＲＦ空洞からの反射電力をある設定した閾値の以内に維持しながら、少しずつＲＦ源の出力ＲＦ電力を高めていく必要がある。冷却水６を提供する冷却水循環システムは、一回の温度調整に相当時間がかかるため、通常水温から目標水温まで安定するには１０分以上必要である。
By making such adjustments, it is necessary to gradually increase the output RF power of the RF source while keeping the reflected power from those RF cavities within a certain set threshold value. Since the cooling water circulation system that provides the cooling
従って、ＲＦ源２は時間をかけて、少しずつ出力ＲＦ電力を高めいくしかない。そうしないと、共振周波数の維持が間に合わない。実際ＢＮＣＴ陽子加速器では、この従来の方法を使って要求された出力までにＲＦを立ち上げるのに、約２０分～３０分ぐらいの時間が必要である。
Therefore, the
故に、従来技術の方法では、加速電場立ち上げの時間がかかるため、医療用の施設としての要求を満たすことができない。その問題を解決しないと、ＢＮＣＴ陽子加速器は最終的に普及可能な信頼できる医療装置に至らない。 Therefore, the method of the prior art cannot meet the demand as a medical facility because it takes time to set up the accelerated electric field. Unless the problem is solved, the BNCT proton accelerator will not eventually become a reliable medical device that can be widely used.
ここで、従来技術を整理すると、
ＢＮＣＴ陽子加速器のような高周波加速器において、一台のＲＦ源を用いて、二つの特性が異なる第一ＲＦ空洞（ＲＦＱ空洞）、チューナーを備える第二ＲＦ空洞（ＤＴＬ空洞）に加速電場を所定の値に到達させる立ち上げ方法であって、
前記ＲＦ源から前記第一ＲＦ空洞及び第二ＲＦ空洞に前記高周波加速器の加速器運転周波数を持つ加速電場を供給し、
前記第一ＲＦ空洞及び前記第二空洞が共振するように、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の冷却水の水温及びチューナーを調整することで、前記第一ＲＦ空洞及び前記第二空洞からの反射を低減させる共振調整工程を経た後、
前記ＲＦ源の出力ＲＦ電力を上げて前記前記第一ＲＦ空洞及び前記第二ＲＦ空洞の温度を上昇させることで前記共振にズレを生じさせ昇温工程を行い、
再び、前記前記第一ＲＦ空洞及び前記第二ＲＦ空洞が共振するように、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の前記冷却水の水温及び前記チューナーを調整し、前記第一ＲＦ空洞及び前記第二空洞からの反射を低減させる再共振調整工程を経る、
一連の前記共振調整工程、昇温工程、再共振調整工程を、
前記ＲＦ源の出力ＲＦ電力が所定の値に到達するまで繰り返す、立ち上げ方法を採用していた。
Here, if the conventional techniques are organized,
In a high-frequency accelerator such as a BNCT proton accelerator, a single RF source is used to set an accelerating electric field in a first RF cavity (RFQ cavity) with two different characteristics and a second RF cavity (DTL cavity) equipped with a tuner. It is a start-up method to reach the value,
An accelerating electric field having an accelerator operating frequency of the high frequency accelerator is supplied from the RF source to the first RF cavity and the second RF cavity.
By adjusting the water temperature and tuner of the cooling water of the first RF cavity and the second RF cavity so that the first RF cavity and the second cavity resonate, the first RF cavity and the second cavity are formed. After going through a resonance adjustment process to reduce reflections from
By increasing the output RF power of the RF source and raising the temperatures of the first RF cavity and the second RF cavity, the resonance is deviated and a temperature raising step is performed.
Again, the water temperature of the cooling water of the first RF cavity and the second RF cavity and the tuner are adjusted so that the first RF cavity and the second RF cavity resonate, and the first RF cavity and the first RF cavity and the tuner are adjusted. The resonance adjustment step of reducing the reflection from the second cavity is performed.
A series of the resonance adjustment step, the temperature rise step, and the resonance adjustment step,
A start-up method has been adopted in which the output RF power of the RF source is repeated until it reaches a predetermined value.
ＲＦ空洞の温度調整は、水冷機構であり、水の温度を設定してからＲＦ空洞の温度が安定するまで数分以上かかる。従来技術における、上記繰り返しサイクルは数十サイクル必要であり、２０分から３０分の立ち上げ時間を要している。医療用高周波加速器などでは患者を待たせる必要があるなど著しい時間的損失が避けられない。 The temperature adjustment of the RF cavity is a water cooling mechanism, and it takes several minutes or more from setting the temperature of water until the temperature of the RF cavity stabilizes. In the prior art, the above-mentioned repeating cycle requires several tens of cycles, and requires a start-up time of 20 to 30 minutes. Significant time loss is unavoidable, such as the need to keep patients waiting in medical high-frequency accelerators.
・本発明
他方、本発明は、図１（２）に示すように、主に、ＢＮＣＴ用に「二つの特性が異なるＲＦ空洞に対して、一台のＲＦ源の出力ＲＦ周波数変調よるＲＦ空洞の加速電場早い立ち上げ方法」という新しい技術を開発した。
具体的には、ＲＦＱ空洞３及びＤＴＬ空洞４の立ち上げの際は、ＱＬ値が高いＲＦ空洞、ＢＮＣＴ陽子加速器ではＤＴＬ空洞４の共振周波数ｆ２を検出して、ＲＦ源の出力ＲＦ周波数ｆｒｆをＤＴＬ共振周波数ｆ２に変調し、それらＲＦ空洞に出力する。同時にＤＴＬ空洞４のチューナー５を調整して、ＤＴＬ空洞４のＤＴＬ共振周波数ｆ２をＲＦＱ共振周波数ｆ１にする。
そうすると、それらＲＦ源の出力ＲＦ周波数ｆｒｆとＤＴＬ空洞の共振周波数ｆ２とＲＦＱ空洞の共振周波数ｆ１、その三つの周波数は同じになるため、それらＲＦ空洞からの反射電力は同時に最小に維持できる。その理由は、ＲＦ電力はＲＦ空洞に入る時、そのＲＦ電力のＲＦ周波数により、ＲＦ空洞内で形成した加速電場と、ＲＦ空洞からの反射電力が変わる。ＲＦ周波数はＲＦ空洞の共振周波数で、ＲＦ空洞内に形成した電場は最大となり、ＲＦ空洞からの反射電力は最小となる。
従って、ＲＦ源の出力ＲＦ電力が所定の値に到達する時間を大幅に短縮することが可能となる。
本発明の方法によれば、立ち上げ中も冷却水入口温度は一定のままでよく、その点からも、加速電場高速立ち上げが可能である。
The present invention On the other hand, as shown in FIG. 1 (2), the present invention is mainly for BNCT, "For RF cavities with two different characteristics, RF cavities by output RF frequency modulation of one RF source. We have developed a new technology called "How to start up the accelerated electric field quickly."
Specifically, when the
Then, since the output RF frequency frf of those RF sources, the resonance frequency f 2 of the DTL cavity, and the resonance frequency f 1 of the RFQ cavity are the same, the reflected power from those RF cavities is maintained to the minimum at the same time. can. The reason is that when the RF power enters the RF cavity, the accelerated electric field formed in the RF cavity and the reflected power from the RF cavity change depending on the RF frequency of the RF power. The RF frequency is the resonance frequency of the RF cavity, the electric field formed in the RF cavity is the maximum, and the reflected power from the RF cavity is the minimum.
Therefore, it is possible to significantly shorten the time for the output RF power of the RF source to reach a predetermined value.
According to the method of the present invention, the cooling water inlet temperature may remain constant even during the start-up, and from this point as well, the accelerated electric field high-speed start-up is possible.
そして、ＢＮＣＴ陽子加速器の立ち上げ試験では、冷却水６の入口水温を一定にして、本発明の新しい加速電場立ち上げの方法を適用すると、加速電場立ち上げの時間は、従来の２０分～３０分から、３分～５分に短縮することができた。
この新しいＲＦの立ち上げの方法である本発明は、現時点で同類の高周波加速器において、はじめての研究開発、実用例である。
Then, in the start-up test of the BNCT proton accelerator, when the inlet water temperature of the cooling
The present invention, which is a method for launching this new RF, is the first research and development and practical example of a high-frequency accelerator of the same type at present.
図２に、（１）従来技術と、（２）本発明を適用したＢＮＣＴ陽子加速器における加速電場立上げの試験結果を示した。 FIG. 2 shows the test results of (1) the prior art and (2) the start-up of the accelerating electric field in the BNCT proton accelerator to which the present invention is applied.
図２の記号の意味は次の通りである。
ｐｆ＿ｋｌｙ：ＲＦ源（ここではｋｌｙｓｔｒｏｎ）の出力ＲＦ電力
Ｐｒ＿ＲＦＱ：ＲＦＱ空洞からの反射電力
Ｐｒ＿ＤＴＬ：ＤＴＬ空洞からの反射電力
Ｄｆｒｑ＿ＤＴＬ＝ｆ２－ｆ０
Ｄｆｒｑ＿ＲＦＱ＝ｆ１－ｆ０
ｆ０：加速器運転周波数
ｆ１：ＲＦＱ共振周波数
ｆ２：ＤＴＬ共振周波数
The meanings of the symbols in FIG. 2 are as follows.
pf_kly: Output RF power of RF source (here, klystron) Pr_RFQ: Reflected power from RFQ cavity Pr_DTL: Reflected power from DTL cavity Dfrq_DTL = f 2 -f 0
Dfrq_RFQ = f 1 -f 0
f 0 : Accelerator operating frequency f 1 : RFQ resonance frequency f 2 : DTL resonance frequency
試験条件は、加速器の運転繰り返しは５０Ｈｚ、ＲＦ幅は１ｍｓ、ＲＦ源の出力ＲＦ電力の所定値は８５０ｋＷ、加速器運転周波数（ｆ０）は３２４ＭＨｚである。 The test conditions are that the accelerator operation is repeated at 50 Hz, the RF width is 1 ms, the predetermined value of the output RF power of the RF source is 850 kW, and the accelerator operation frequency (f 0 ) is 324 MHz.
従来技術では、（１）のグラフに、ＲＦ源の出力ＲＦ電力が、縦軸０から所定値まで、つまり、加速電場立上げ所要時間は２０～３０分であった。他方、本発明では、（２）のグラフに、ＲＦ源の出力ＲＦ電力が０から所定値まで、また両空洞（ＲＦＱ空洞とＤＴＬ空洞）の共振周波数ｆ１及びｆ２が加速器運転周波数ｆ０と一致するまで、すなわち、縦軸において、Ｄｆｒｑ＿ＲＦＱ＝ｆ１－ｆ０＝０、Ｄｆｒｑ＿ＤＴＬ＝ｆ２－ｆ０＝０になるまで、つまり、加速電場立上げ所要時間は３～５分に短縮され、加速電場高速立ち上げ方法であることがわかる。 In the prior art, in the graph of (1), the output RF power of the RF source is from 0 on the vertical axis to a predetermined value, that is, the time required to set up the accelerated electric field is 20 to 30 minutes. On the other hand, in the present invention, in the graph of (2), the output RF power of the RF source is from 0 to a predetermined value, and the resonance frequencies f1 and f2 of both cavities (RFQ cavity and DTL cavity) coincide with the accelerator operating frequency f0 . That is, until Dfrq_RFQ = f 1 -f 0 = 0 and Dfrq_DTL = f 2 -f 0 = 0 on the vertical axis , that is, the time required to start the accelerator electric field is shortened to 3 to 5 minutes and accelerated. It can be seen that this is a method for starting up the electric field at high speed.
グラフに、ＲＦ源の出力ＲＦ電力が０（縦軸）から所定値まで、また両空洞（ＲＦＱ空洞とＤＴＬ空洞）の共振周波数が加速器運転周波数と一致（特にＤＴＬ空洞の共振周波数が加速器運転周波数と一致）なったころから、つまり、加速電場立ち上げ時間は、２分５０秒であることがわかる。 In the graph, the output RF power of the RF source is from 0 (vertical axis) to a predetermined value, and the resonance frequencies of both cavities (RFQ cavity and DTL cavity) match the accelerator operating frequency (especially the resonance frequency of the DTL cavity is the accelerator operating frequency). It can be seen that the start-up time of the accelerator electric field is 2 minutes and 50 seconds.
図３の記号の意味は次の通りである。
Ｄｆｒｑ＿ＲＦＱ＝ｆ１－ｆ０
Ｄｆｒｑ＿ＤＴＬ＝ｆ２－ｆ０
その中
ｆ０：加速器運転周波数
ｆ１：ＲＦＱ共振周波数
ｆ２：ＤＴＬ共振周波数
ｐｆ＿ｋｌｙ／１０：ＲＦ源（ここではｋｌｙｓｔｒｏｎ）の出力ＲＦ電力の１０分の１という
Ｐｒ＿ＲＦＱ：ＲＦＱ空洞からの反射電力
Ｐｒ＿ＤＴＬ：ＤＴＬ空洞からの反射電力
The meanings of the symbols in FIG. 3 are as follows.
Dfrq_RFQ = f 1 -f 0
Dfrq_DTL = f 2 -f 0
Among them, f 0 : Accelerator operating frequency f 1 : RFQ resonance frequency f 2 : DTL resonance frequency pf_kly / 10: 1/10 of the output RF power of the RF source (here, klystron) Pr_RFQ: Reflected power from the RFQ cavity Pr_DTL : Reflected power from DTL cavity
試験条件は、加速器の運転繰り返しは５０Ｈｚ、ＲＦ幅は１ｍｓ、ＲＦ源の出力ＲＦ電力の所定値は８５０ｋＷ、加速器運転周波数（ｆ０）は３２４ＭＨｚである。 The test conditions are that the accelerator operation is repeated at 50 Hz, the RF width is 1 ms, the predetermined value of the output RF power of the RF source is 850 kW, and the accelerator operation frequency (f 0 ) is 324 MHz.
本発明は、医療用分野において、低コスト、省スペースで、医療用高周波加速器を提供することができる。 INDUSTRIAL APPLICABILITY The present invention can provide a medical high-frequency accelerator in the medical field at low cost and space saving.
１ ＬＬＲＦシステム
２ ＲＦ源
３ ＲＦＱ空洞
４ ＤＴｌ空洞
５ チューナー
６ 冷却水
1
Claims (4)
前記第一ＲＦ空洞及び前記第二ＲＦ空洞の起動時に、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の両方の共振周波数を検出し、
前記ＲＦ源から前記第一ＲＦ空洞及び前記第二ＲＦ空洞に出力する前記ＲＦ電力の前記ＲＦ周波数を、前記検出にて得た前記共振周波数のいずれか一方に一致させるよう変調し、変調した周波数である変調周波数で、前記第一ＲＦ空洞及び前記第二ＲＦ空洞に前記ＲＦ電力を出力するとともに、
前記チューナーを制御して、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の共振周波数を同じにすることで、
前記第一ＲＦ空洞及び前記第二ＲＦ空洞の共振周波数と前記ＲＦ電力の前記ＲＦ周波数を同じにし、
前記第一ＲＦ空洞及び前記第二ＲＦ空洞からの反射電力を低減させることで、
前記ＲＦ源から出力され、前記第一ＲＦ空洞及び前記第二ＲＦ空洞を駆動する前記ＲＦ電力及び前記ＲＦ周波数を所定値に短時間で到達させ、前記第一ＲＦ空洞及び前記第二ＲＦ空洞の加速電場を高速に所定の電場に形成することを特徴とする
ＲＦ空洞に加速電場を高速で立ち上げ方法。 By outputting and supplying RF power, which is a driving power, to the first RF cavity and the second RF cavity having a tuner, and the first RF cavity and the second RF cavity having different characteristics at an RF frequency, the first RF cavity and the second RF cavity have different characteristics. In a high frequency accelerator equipped with one RF source for forming an accelerating electric field in the RF cavity and the second RF cavity.
At the time of activation of the first RF cavity and the second RF cavity, the resonance frequencies of both the first RF cavity and the second RF cavity are detected.
The RF frequency of the RF power output from the RF source to the first RF cavity and the second RF cavity is modulated and modulated so as to match one of the resonance frequencies obtained by the detection. At the modulation frequency of, the RF power is output to the first RF cavity and the second RF cavity, and the RF power is output.
By controlling the tuner to make the resonance frequencies of the first RF cavity and the second RF cavity the same,
The resonance frequency of the first RF cavity and the second RF cavity and the RF frequency of the RF power are made the same.
By reducing the reflected power from the first RF cavity and the second RF cavity,
The RF power and the RF frequency output from the RF source and driving the first RF cavity and the second RF cavity are brought to a predetermined value in a short time, and the first RF cavity and the second RF cavity are formed. A method of setting up an accelerating electric field at high speed in an RF cavity, which is characterized by forming an accelerating electric field into a predetermined electric field at high speed.
請求項１に記載のＲＦ空洞に加速電場を高速で立ち上げ方法。 The method for setting up an accelerated electric field in an RF cavity according to claim 1, wherein the first RF cavity is an RFQ cavity and the second RF cavity is a DTL cavity.
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