JP2004247191A

JP2004247191A - Charged particle beam accelerating device and charged particle beam accelerator

Info

Publication number: JP2004247191A
Application number: JP2003036226A
Authority: JP
Inventors: Nobuyuki Zumoto; 信行頭本; Takahisa Nagayama; 貴久永山; Hiroko Kijima; 裕子来島
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2003-02-14
Filing date: 2003-02-14
Publication date: 2004-09-02

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charged particle beam accelerating device and a charged particle beam accelerator using the same with improved cooling efficiency and easy to manufacture. <P>SOLUTION: The device for making charged particle beams pass through a hollow part of circular cores 4 or cores arranged in a circle with a part of the circle lacking and accelerating the beams by an induction field originating in magnetic flux density changing with time inside the cores, is provided with a heat transmission wall 11a closely arranged in the cores 4, an opposite wall 11b arranged in opposition to the heat transmission wall with an interval through an interval-holding member 12, and a cooling vessel 1 equipped with a guide-in hole 3a and a guide-out hole 3b for a coolant and with the coolant flowing inside. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
本発明は、磁心内で時間変化する磁束密度に起因する誘導電場により荷電粒子ビームを加速する装置およびそれを用いた荷電粒子ビーム加速器に関し、特に、磁心の冷却構造に関するものである。
【０００２】
【従来の技術】
従来の技術について説明する前に、まず、本発明で言う荷電粒子ビーム加速装置および荷電粒子ビーム加速器の定義を説明する。
本発明で言う荷電粒子ビーム加速装置とは、いわゆる荷電粒子ビーム加速器のうちの荷電粒子ビームを加速する部分を指し、荷電粒子ビーム加速装置に荷電粒子ビームを周回させる偏向電磁石を加えたものを荷電粒子ビーム加速器と定義する。
【０００３】
すなわち、荷電粒子ビームの軌道を囲むように環状または環の一部を欠いて環状に設置され、中空部に荷電粒子ビームを通過させ、磁束密度の時間変化に起因する誘導電場により荷電粒子ビームを加速する磁心、磁心内の磁束密度を時間変化させる励磁手段、および磁心を冷却する手段からなる荷電粒子ビーム加速手段を荷電粒子ビーム加速装置とよぶ。
荷電粒子ビーム加速装置としては、例えば、一般に加速コアと呼ばれるものと、高周波加速空洞と呼ばれるものを挙げることができる。加速コアと呼ばれるものは、磁心内の磁束密度を時間変化させる励磁手段が、磁心に巻きつけ高周波電源を接続した励磁コイルからなり、高周波加速空洞と呼ばれるものは、磁心内の磁束密度を時間変化させる励磁手段が、磁心を取り囲み中心部に設けた環状の開口部の両端に高周波電圧を印加する高周波空洞からなる。
【０００４】
上記のように定義される従来の荷電粒子ビーム加速装置においては、例えば、筒状に形成された内部導体および外部導体を同軸的に配置し、内部導体と外部導体とで構成される空間内にフェライトディスクとフェライトディスク冷却板とを軸方向に交互に積層して構成された半共振器が、軸方向に並設されてなるフェライト装荷型高周波加速空洞において、前記フェライトディスク冷却板が、良熱伝導体からなるリング状で、外周面に溝が形成された熱伝導板と、良熱伝導体からなり、前記熱伝導板の溝に周方向に配置されてロウ付けされた、冷媒が流通される冷却パイプとから構成されている。また、筒状に形成された内部導体および外部導体を同軸的に配置し、内部導体と外部導体とで構成される空間内にフェライトディスクを軸方向に積層して構成された半共振器が、軸方向に並設されてなるフェライト装荷型高周波加速空洞において、前記フェライトディスクは、その端面に渦巻き状の溝が形成され、該溝内に良熱伝導体で構成された冷媒を流通させる冷却パイプが配設されている（例えば、特許文献１参照）。
【０００５】
【特許文献１】
特開平８−３３９８９８号公報（第２−８頁、第１−１０図）
【０００６】
【発明が解決しようとする課題】
従来の荷電粒子ビーム加速装置は以上のような構成となっているので、フェライトディスクの側面に設置したリング状の熱伝導板の外周面に、冷媒が流通される冷却パイプを配置して冷却する構成では、リング状の熱伝導体の熱伝導率によってコア中心部の温度が決まるので、発熱量が大きい場合には、フェライトディスクの中心部を十分低い温度まで冷却できないという問題がある。また、熱伝導板の外周面に溝を形成するのに手間がかかるという問題もある。
また、フェライトディスクの端面に渦巻き状の溝が形成され、該溝内に良熱伝導体で構成された冷媒を流通させる冷却パイプが配設された構成では、フェライトディスクの端面に渦巻き状の溝を形成するのに手間がかかり、しかも、冷媒を大量に流す必要がある大発熱量の場合に、冷媒流通路の隔壁部分を出来るだけ薄く形成する必要があるが、薄くするのに限界があるという問題がある。
【０００７】
本発明は、冷却効率が向上し、しかも製造が容易な荷電粒子ビーム加速装置およびそれを用いた荷電粒子ビーム加速器を提供することを目的とするものである。
【０００８】
【課題を解決するための手段】
本発明に係わる荷電粒子ビーム加速装置は、環状の磁心または環の一部を欠いて環状に配置した磁心の中空部に荷電粒子ビームを通過させ、前記磁心内で時間変化する磁束密度に起因する誘導電場により該荷電粒子ビームを加速する装置であって、前記磁心に密着配置された伝熱壁と、間隔保持部材を介して前記伝熱壁と間隔を空けて対向配置された対向壁と、冷媒の導入口および導出口とを有し、内部を冷媒が流通する冷却容器を備えたものである。
【０００９】
また、本発明に係わる荷電粒子ビーム加速器は、上記の荷電粒子ビーム加速装置と、荷電粒子ビームを周回させる偏向電磁石とを備えたものである。
【００１０】
【発明の実施の形態】
実施の形態１．
図１は本発明の実施の形態１による荷電粒子ビーム加速装置の要部の構成を示し、（ａ）は側面図、（ｂ）は対向壁を取り除いて冷却容器の側から見た平面図である。
本実施の形態による荷電粒子ビーム加速装置は、荷電粒子ビームの軌道を囲むように環状に設置され、中空部に荷電粒子ビームを通過させ、磁束密度の時間変化に起因する誘導電場により荷電粒子ビームを加速する磁心４、磁心４内の磁束密度を時間変化させる励磁手段、および磁心を冷却する手段を備えているが、図１では要部の構成を示しており、励磁手段は図示していない。また、励磁手段が、磁心に巻きつけ高周波電源を接続した励磁コイルからなる、加速コアと呼ばれる荷電粒子ビーム加速装置、および励磁手段が、磁心を取り囲み中心部に設けた環状の開口部の両端に高周波電圧を印加する高周波空洞からなる、高周波加速空洞と呼ばれる荷電粒子ビーム加速装置の何れであってもよい。
【００１１】
本実施の形態による荷電粒子ビーム加速装置は、環状の磁心４に密着配置された伝熱壁１１ａと、間隔保持部材を介して伝熱壁１１ａと間隔を空けて対向配置された対向壁１１ｂと、冷媒の導入口（以下、冷媒導入口と称する。）３ａおよび導出口（以下、冷媒導出口と称する。）３ｂとを有し、内部を冷媒が流通する冷却容器１を備えている。１１ｃは側壁である。冷却容器１は伝熱壁１１ａと対向壁１１ｂと側壁１１ｃとで囲まれた密閉された容器であり、本実施の形態では側壁１１ｃの対向する位置に冷媒導入口３ａと冷媒導出口３ｂとが配置されている。
また、伝熱壁１１ａと対向壁１１ｂ間に配置され、冷媒導入口３ａから冷媒導出口３ｂへ至る冷媒の流路２を形成するガイド部材１２を備え、ガイド部材１２が間隔保持部材を兼ねている。本実施の形態では、ガイド部材１２は、複数の流路２を形成している。
なお、図中、矢印は冷媒の流れを示している。
【００１２】
以下、より具体的に説明する。環状の磁心４の側面に密着させた冷却容器１は、二枚の平板（伝熱壁１１ａと対向壁１１ｂに相当する。）とその内部に複数の互いに平行な隔壁（ガイド部材１２に相当する。）を設置して冷却水（冷媒に相当する。）の流路２としている。
【００１３】
本実施の形態では、伝熱壁１１ａ、対向壁１１ｂ、側壁１１ｃおよびガイド部材１２としては、熱伝導性を重視して、良熱伝導性金属である銅やステンレス鋼などを使用している。磁心４と冷却容器１（すなわち伝熱壁１１ａ）との間には、例えば、数十μｍ厚程度の電気絶縁性のポリイミドフイルムを、電気絶縁性の熱伝性グリス（例えばシリコングリス）を介して挟み込んで密着させている。伝熱壁１１ａおよび対向壁１１ｂと、側壁１１ｃおよびガイド部材１２との接合は、スポット溶接や接着剤によるが、冷却容器１内部のガイド部材１２は、伝熱壁１１ａと対向壁１１ｂ間の間隔を保持する間隔保持部材としての機能と流路２を規定する機能があれば十分であるので、ガイド部材１２の伝熱壁１１ａおよび対向壁１１ｂとの対向面は必ずしも全ての面が完全に接合されていなくてもよい（すなわち、完全な防水仕様である必要はない。）。したがって、製造も容易で、コストも低く抑えられる。
【００１４】
このように、本実施の形態によれば、二枚の平板（伝熱壁１ａと対向壁１ｂ）と間隔保持部材を兼ねるガイド部材１２による立体構造で冷却容器１の構造強度をもたせるので、特に磁心４に密着する側の平板（伝熱壁１ａ）の厚みを薄くでき、冷却効率を向上できる。すなわち、冷媒と磁心４との間が薄い平板（伝熱壁１ａ）であることから発熱量が大きい場合も磁心４を従来より低い温度まで冷却することができる。
さらに、内部を冷媒が流通する冷却容器１を磁心４に密着配置したので、冷却面積（冷媒によって冷却される部分の面積）を大きくすることができ、冷却効率が向上する。
しかも、上記のように、スポット溶接や接着剤によって作製した冷却容器１を、ポリイミドフイルムを熱伝性グリスを介して挟み込んで磁心４に密着させるので、従来例のように、熱伝導板の外周面やフェライトディスクの端面に溝を形成する必要がなく、切削加工が不要で製造が容易である。
【００１５】
さらに、本実施の形態では、複数の流路２を形成し、冷却水の導入部（冷媒導入口３ａに相当する。）は各ガイド部材１２間（各流路２に相当する。）のそれぞれに設けてあり、大流量の冷却水を導入できるので、磁心４の発熱が大きい場合にも高い冷却性能が得られる。
【００１６】
なお、図１では、ガイド部材１２として平板を使用しているが、図２に示すように、波板を用い、伝熱壁１１ａに平行な断面における形状を波形状としてもよい。
これにより、全体の構造強度がさらに高まるので、ガイド部材１２をさらに薄くでき、冷却効率をさらに向上できる。
【００１７】
なお、上記実施の形態では磁心４が環状である場合について示したが、環の一部を欠いて環状に配置した磁心であってもよい。これは、以下の各実施の形態においても、特に断らないが同様である。
【００１８】
また、上記実施の形態では冷媒が冷却水である場合について説明したが、これに限るものではなく、さまざまな液体および気体を用いることができる。これは、以下の各実施の形態においても、特に断らないが同様である。
【００１９】
実施の形態２．
図３は本発明の実施の形態２による荷電粒子ビーム加速装置の要部の構成を示す図であり、対向壁を取り除いて冷却容器の側から見た平面図である。
上記実施の形態１では、ガイド部材は、複数の流路２を形成するように設置されていたが、本実施の形態では、ガイド部材１２は一本の流路２を形成するように設置されている。他の構成は実施の形態１と同様である。
【００２０】
本実施の形態においても、実施の形態１の場合と同様の効果が得られる。
また、冷却水の量は実施の形態１に比較すると減少するが、冷却水の導入部（冷媒導入口３ａ）、取出し部（冷媒導出口３ｂ）がそれぞれ１箇所ですむので、磁心４の発熱が小さい場合には有効であり、この場合、冷却容器１の構造が簡単化し、加速装置コストが低減するという効果がある。
【００２１】
なお、ガイド部材１２として、平板の代わりに波板を用い、伝熱壁１１ａに平行な断面における形状を波形状としてもよく、これにより、全体の構造強度がさらに高まるので、ガイド部材１２をさらに薄くでき、冷却効率をさらに向上できるのは、実施の形態１の場合と同様である。
【００２２】
実施の形態３．
図４は本発明の実施の形態３による荷電粒子ビーム加速装置の要部の構成を示す図であり、対向壁を取り除いて冷却容器の側から見た平面図である。
上記実施の形態２では、ガイド部材１２は、折り返された一本の流路２を形成するように設置されていたが、本実施の形態では、ガイド部材１２は渦巻状の一本の流路２を形成するように設置されている。他の構成は実施の形態２と同様である。
【００２３】
本実施の形態においても、実施の形態２の場合と同様の効果が得られる。
また、通常、磁心４の発熱は磁心４中央部が大きいが、本実施の形態による冷却容器１は、冷却水を、図４に矢印で示すように、磁心４の中央部から外側に向けて流すことができるので、実施の形態２と比較して磁心４の冷却効率が向上する結果、冷却容器１総合の冷却効率が向上する。したがって、冷却容器１に冷却水を供給する冷却機器の小型化、低コスト化が可能になるという効果がある。
【００２４】
なお、ガイド部材１２として、平板の代わりに波板を用い、伝熱壁１１ａに平行な断面における形状を波形状としてもよく、これにより、全体の構造強度がさらに高まるので、ガイド部材１２をさらに薄くでき、冷却効率をさらに向上できるのは、実施の形態１の場合と同様である。
【００２５】
実施の形態４．
図５は本発明の実施の形態４による荷電粒子ビーム加速装置の要部の構成を示す図であり、冷却容器を対向壁の側から見た平面図である。
上記実施の形態１では、側壁１１ｃの対向する位置に冷媒導入口３ａと冷媒導出口３ｂとが配置されていたが、本実施の形態では、複数の流路２は放射状に形成されており、各流路２の冷媒導入口３ａは対向壁１１ｂの中央部に、各流路２の冷媒導出口３ｂは対向壁１１ｂの周縁部にそれぞれ設けられている。他の構成は実施の形態１と同様である。
【００２６】
本実施の形態においても、実施の形態１の場合と同様の効果が得られる。
また、冷媒導入口３ａおよび冷媒導出口３ｂは対向壁１１ｂに設け（伝熱壁に対して垂直に冷媒の導入および取り出しが可能であるように設け）、冷却容器１中空部の領域を広く取れるので、中空部に設置される電磁石のサイズが同じだとすると磁心および冷却容器の周長を短く、すなわちサイズを小型化できる。
通常、磁心４の発熱は磁心４中央部が大きいが、本実施の形態による冷却容器１では磁心４の中央部から冷却水３を導入するので、磁心４の発熱が大きい場合に有効であった実施の形態１と比較して冷却性能がさらに向上するという効果がある。
また、一本の流路２で磁心４中央部から冷却している実施の形態３と比較して、本実施の形態では複数の流路２を設けているので、冷却能力がさらに高くなる。その結果、磁心４損失の増大する高加速電圧化が可能となり、荷電粒子ビーム加速器に組み込んだ場合、そのビーム電流を増大できるという効果がある。
【００２７】
なお、図５では、ガイド部材１２として平板を使用しているが、図６に示すように、波板を用い、伝熱壁（図６では図示していない。）に平行な断面における形状を波形状としてもよい。
これにより、全体の構造強度がさらに高まるので、ガイド部材１２をさらに薄くでき、冷却効率をさらに向上できる。
【００２８】
また、図５および図６では、冷媒導入口３ａおよび冷媒導出口３ｂを共に対向壁１１ｂに設けた例を示したが、磁心４および冷却容器１の形状によっては、何れか一方のみを対向壁１１ｂに設けてもよく、さらには、冷媒導入口３ａおよび冷媒導出口３ｂの少なくとも何れか一方を伝熱壁（図５および図６では図示していない。）に設けてもよい。
【００２９】
実施の形態５．
図７は本発明の実施の形態５による荷電粒子ビーム加速装置の要部の構成を示す図であり、冷却容器の側から見た平面図である。
上記実施の形態１では、冷媒導入口３ａと冷媒導出口３ｂとが、側壁１１ｃの対向する位置に配置されていたが、本実施の形態では、側壁１１ｃの一箇所（一側面）に並んで設置されている。他の構成は実施の形態１と同様である。
【００３０】
本実施の形態においても、実施の形態１の場合と同様の効果が得られる。
また、実施の形態１ほどではないが、実施の形態２および３よりも冷却水量を大流量にでき、かつ給排水口（冷媒導入口３ａと冷媒導出口３ｂ）の設置個所が側壁１１ｃの一側面のみであるので、冷却系を小型化、低コスト化できるという効果がある。
【００３１】
なお、ガイド部材１２として、平板の代わりに波板を用い、伝熱壁（図７では図示していない。）に平行な断面における形状を波形状としてもよく、これにより、全体の構造強度がさらに高まるので、ガイド部材１２をさらに薄くでき、冷却効率をさらに向上できるのは、実施の形態１の場合と同様である。
【００３２】
実施の形態６．
図８は本発明の実施の形態６による荷電粒子ビーム加速装置の要部の構成を示す図であり、対向壁を取り除いて冷却容器の側から見た平面図である。
上記各実施の形態では、冷媒導入口３ａから冷媒導出口３ｂへ至る冷媒の流路２を形成するガイド部材１２を備え、ガイド部材１２が間隔保持部材を兼ねる場合について説明したが、本実施の形態では、ガイド部材１２を備えておらず、間隔保持部材１３を備えている。他の構成は実施の形態１と同様であるので、以下では主に実施の形態１と異なる点について説明する。
【００３３】
以下、より具体的に説明する。本実施の形態では、冷却容器１は、伝熱壁１１ａと対向壁（図８では図示していない。）に相当する二枚の平板の間に円柱（間隔保持部材１３に相当する。）を設置して冷却容器１の形状を保持している。冷却容器１と円柱（間隔保持部材１３）の材質は良熱伝導材として例えば銅やステンレス鋼などを使用し、円柱（間隔保持部材１３）と平板（伝熱壁１１ａと対向壁）との機械的な接続はスポット溶接などで行なう。二枚の平板（伝熱壁１１ａと対向壁）の周端部には平板（側壁１１ｃに相当する。）を溶接し、流路２を確保している。冷却容器１へ冷却水を導入および導出する冷媒導入口３ａおよび冷媒導出口３ｂは、側壁１１ｃの対向する位置に冷却容器１に冷却水を供給する冷却機器の能力の許す限りの断面積で設け、冷却効率を高めている。
【００３４】
なお、円柱（間隔保持部材１３）の太さや配置間隔などについては、冷却容器１の形状や冷媒の圧力などに応じて適宜決定される。
【００３５】
本実施の形態においても、実施の形態１の場合と同様の効果が得られる。
また、冷却水の流量を最大限にとることができ、冷却効率を向上できる結果、冷却容器１に冷却水を供給する冷却機器の小型化、低コスト化が可能になるという効果がある。
【００３６】
なお、間隔保持部材１３は円柱に限るものではなく、角柱やＬ字状の柱など他の形状であってもよいのは言うまでもない。
【００３７】
さらに、間隔保持部材１３とガイド部材１２とが混在していてもよい。
また、ガイド部材１２の一部が伝熱壁１１ａおよび対向壁の両方に固定されて間隔保持部材１３を兼用し、他の部分は伝熱壁１１ａおよび対向壁の少なくとも何れか一方との間に隙間を設けた構成であってもよい。
【００３８】
実施の形態７．
本実施の形態による荷電粒子ビーム加速装置は、荷電粒子ビームの軌道を囲むように環状に設置され、中空部に荷電粒子ビームを通過させ、磁束密度の時間変化に起因する誘導電場により荷電粒子ビームを加速する磁心４、磁心４内の磁束密度を時間変化させる励磁手段、および磁心を冷却する手段を備えており、励磁手段が、磁心を取り囲み中心部に設けた環状の開口部の両端に高周波電圧を印加する高周波空洞からなる、高周波加速空洞と呼ばれる荷電粒子ビーム加速装置である。
【００３９】
上記各実施の形態では、冷却容器１（伝熱壁１１ａ、対向壁１１ｂ、側壁１１ｃ、ガイド部材１２、間隔保持部材１３）は冷却効率を高めるために、熱伝導性を重要視して、材料として銅やステンレス鋼のような良熱伝導性金属を使用しているが、本実施の形態では、冷却容器１を例えば、エンジニアリングプラスチック（例えばカプトン、ＭＣナイロンなど）、ＦＲＰ、ＴｉＮ、アルミナのような電気絶縁性材料で形成し、寄生静電容量の問題（後で詳細に説明する。）を回避するようにしている。
【００４０】
この場合、上記のような電気絶縁性材料は良熱伝導性金属に比べて熱伝導性が劣るが、実施の形態１で説明したように、伝熱壁１ａと対向壁１ｂと間隔保持部材（ガイド部材１２）による立体構造で冷却容器１の構造強度をもたせるので、特に磁心４に密着する側の伝熱壁１ａの厚みを薄くできる結果、伝熱壁１ａの材料を良熱伝導性金属から上記のような電気絶縁性材料に置き換えても十分な冷却性能が得られる。
【００４１】
以下、寄生静電容量について説明する。磁心４の冷却効率を上げるために、磁心４の両側に電気伝導体からなる冷却容器１を設置した場合、寄生静電容量が発生し高周波加速空洞のインピーダンスが低下する。インピーダンス低下は電源負荷を増大させるので高出力電源が必要となり、励磁電源の製作が困難になるという問題がある。
【００４２】
上記問題を、図９および図１０に従ってさらに詳細に説明する。図９は環状の磁心および冷却容器の片側断面のみを示している。通常の磁心４は導電性のアモルファスシートに絶縁膜を塗布し巻きつけて製作してあり、磁束を囲む閉ループで発生する渦電流損を抑えるようにしている。したがって、磁心４の巻き取り方向（積層方向）には導電性が無いが、厚み方向には導電性が有る構造となっている。
この場合、冷却効率を上げるために磁心４の両側に冷却容器１を設置すると、共に導電性である磁心４と冷却容器１との間には電気絶縁層１９（電気絶縁性のポリイミドフイルムおよび熱伝性グリス）を挟んでいるので、コンデンサが形成されることになるため、高周波加速空洞に並列に静電容量（寄生静電容量）Ｃが挿入されるのと等価となり、図９を等価回路で表すと図１０に示すようになる。ここで、図９に示すように磁束密度Ｂの時間変化が紙面に垂直方向に発生すると、図９の矢印で示す方向に高周波の誘導起電力が生じるが、上記寄生静電容量Ｃの存在により、高周波誘導起電力に対しては電流パスが存在することになるため、インピーダンス低下の問題を発生させる。
【００４３】
なお、冷却容器１のうち伝熱壁１ａが、静電容量Ｃへの影響が最も大きいが、上記各実施の形態で説明した冷却容器１は、何れも、伝熱壁１ａと対向壁１ｂと間隔保持部材１３（または間隔保持部材を兼ねるガイド部材１２）による立体構造で冷却容器１の構造強度をもたせるので、特に磁心４に密着する側の伝熱壁１ａの厚みを薄くできる結果、上記各実施の形態のように冷却容器１を良熱伝導性金属で形成した場合にも静電容量Ｃはそれほど大きなものとはならないが、本実施の形態のように、冷却容器１を電気絶縁性材料で形成することにより、より確実に静電容量（寄生静電容量）Ｃの影響によるインピーダンス低下の問題を防止することができる。
【００４４】
なお、冷却容器１のうち静電容量Ｃへの影響が最も大きい伝熱壁１ａのみを電気絶縁性材料で形成してもよく、この場合にも同様の効果が得られる。
【００４５】
実施の形態８．
図１１は本発明の実施の形態８による荷電粒子ビーム加速器の要部の構成を示し、（ａ）は正面図、（ｂ）は（ａ）のＢ−Ｂ線での断面図、（ｃ）は（ｂ）のＣ−Ｃ線での断面図である。ただし、（ｃ）は（ｂ）のＣ−Ｃ線での断面図のうちの高周波空洞の部分を示している。
本実施の形態による荷電粒子ビーム加速器は上記各実施の形態のうちの何れかに記載された荷電粒子ビーム加速装置と、荷電粒子ビームの軌道を規定するための磁場が時間変化して荷電粒子ビームを周回させる偏向電磁石とを備えたものである。
【００４６】
本実施の形態による荷電粒子ビーム加速器は、より詳細には、荷電粒子ビームの軌道を囲むように設置され磁束密度の時間変化に起因する誘導電場により荷電粒子ビームを加速する磁心４、磁心４を取り囲み中心部に設けた環状の開口部の両端に励磁電源２１により高周波電圧を印加される高周波空洞２０、および磁心４の側面に設置された冷却容器１からなる高周波加速空洞（荷電粒子ビーム加速装置に相当する。）と、内部を真空に保ち荷電粒子ビームを周回させる真空ダクト２３と、荷電粒子ビームの軌道を真空ダクト２３内に維持する（すなわち荷電粒子ビームを周回させる）ために、真空ダクト２３を挟むように複数個設置される偏向電磁石２２と、真空ダクト２３に対して荷電粒子ビームを入射させる入射器（図示せず）と、荷電粒子ビームを取り出すビーム取り出し機器（図示せず）とから主に構成される。
なお、真空ダクト２３は、磁心４に囲まれた位置において電気絶縁性のギャップを設けてあり、この位置で加速電場を発生させるようになっている。
【００４７】
次に動作について説明する。ビーム入射器（図示せず）から荷電粒子ビームを出射させ、真空ダクト２３内に導入する。このとき励磁電源２１の励磁周波数は導入された荷電粒子ビームの回転に同期させ、荷電粒子ビームを一方向に繰り返し加速するように変化させる。加速された荷電粒子ビームは偏向電磁石２２により進路を曲げられ、環状の真空ダクト２３中を周回し（ほぼ円運動し）、励磁電源２１電圧が印加されている間、継続的に加速される。このとき、荷電粒子ビームの周回軌道を維持するため加速に応じて偏向電磁石２２による磁場を増加させる（荷電粒子ビームの軌道を規定するための磁場が時間変化する）。その後、所定の荷電粒子ビームエネルギーに達した段階でビーム出射器（図示せず）により取り出しを行なう。
【００４８】
なお、図１１では、荷電粒子ビーム加速装置として高周波加速空洞と呼ばれる種類のものを用いた場合を示しているが、これに限るものではなく、加速コアと呼ばれる種類のものを用いてもよい。
【００４９】
このように、本実施の形態による荷電粒子ビーム加速器では、上記実施の形態１〜７のうちの何れかに記載された荷電粒子ビーム加速装置を用いており、冷却容器１は冷却効率が高いので、磁心４を小型化および低コスト化できる。その結果、荷電粒子ビーム加速器も小型化および低コスト化できるという効果が得られる。
【００５０】
特に、荷電粒子ビーム加速装置として高周波加速空洞と呼ばれる種類のものを用いる場合に、上記実施の形態７で説明したように、少なくとも伝熱壁を電気絶縁性材料で形成することにより、寄生静電容量が発生し高周波加速空洞のインピーダンスが低下するのを確実に防止できる。その結果、高出力電源が不要になり低出力な電源で励磁できるようになるので、電源コストを低減できるという効果がある。
【００５１】
実施の形態９．
図１２は本発明の実施の形態９による荷電粒子ビーム加速器の要部の構成を示し、（ａ）は正面図、（ｂ）は（ａ）のＢ−Ｂ線での断面図である。
本実施の形態による荷電粒子ビーム加速器は上記各実施の形態のうちの何れかに記載された荷電粒子ビーム加速装置と、荷電粒子ビームの軌道を規定するための磁場を、荷電粒子ビーム周回軌道の径が大きくなる方向に単調増加で変化させ、時間的には一定として荷電粒子ビームを周回させる偏向電磁石とを備えたものである。
【００５２】
本実施の形態による荷電粒子ビーム加速器（ベータトロン加速器）は、より詳細には、荷電粒子ビームの軌道を囲むように設置され磁束密度の時間変化に起因する誘導電場により荷電粒子ビームを加速する磁心４、磁心４に巻きつけ磁心励磁電源２５（高周波電源）を接続した励磁コイル２４、および磁心４の側面に設置された冷却容器１からなる加速コア（荷電粒子ビーム加速装置に相当する。）と、内部を真空に保ち荷電粒子ビームを周回させる真空ダクト２３と、荷電粒子ビームの軌道を真空ダクト２３内に維持する（すなわち荷電粒子ビームを周回させる）ために、該真空ダクト２３を挟むように複数個設置される偏向電磁石２２と、真空ダクト２３に対して荷電粒子ビームを入射させる入射器（図示せず）と、荷電粒子ビームを取り出すビーム取り出し機器（図示せず）とから主に構成される。
【００５３】
次に動作について説明する。ビーム入射器（図示せず）から荷電粒子ビームを出射させ、環状の真空ダクト２３の中心から内部に導入を開始する。この時点から磁心励磁電源２５電圧を高電圧とすると、磁心４の断面を取り囲む荷電粒子ビームの軌道上に励磁電圧に等しい誘導電場が発生し、荷電粒子ビームが加速を開始する。加速された荷電粒子ビームは偏向電磁石２２により進路を曲げられ、環状の真空ダクト２３中を周回し（ほぼ円運動し）、磁心励磁電源２５電圧が印加されている間、継続的に加速される。偏向電磁石２２による磁場は、荷電粒子ビームの周回軌道の径方向を外側に向けて単調増加する（すなわち荷電粒子ビーム周回軌道の径が大きくなる方向に単調増加する）ように設計されており、速度の増加した荷電粒子の軌道を大きく広げることなく荷電粒子ビームを真空ダクト２３内に閉じ込めることを可能としている。荷電粒子ビームエネルギーが所定の値に達したときに環状の真空ダクト２３の外縁に設置したビーム出射器（図示せず）により取り出しを行なう。
【００５４】
なお、図１２では、荷電粒子ビーム加速装置として加速コアと呼ばれる種類のものを用いた場合を示しているが、これに限るものではなく、高周波加速空洞と呼ばれる種類のものを用いてもよい。
【００５５】
なお、上記例では偏向電磁石２２による磁場は荷電粒子ビーム周回軌道の径方向の外側に向けて単調増加する（すなわち、荷電粒子ビーム周回軌道の径が大きくなる方向に単調増加する）ようにしているが、径方向の内側に向けて単調増加する（すなわち、荷電粒子ビーム周回軌道の径が大きくなる方向に単調減少する）ようにしてもよい。この場合は上記例の逆で、荷電粒子ビームはエネルギーが増加するほど径方向の内側に引き寄せられる。したがって、環状の真空ダクト２３の外側からビームを入射し、内側からビームを取り出すようにする。
【００５６】
通常のベータトロン加速器の偏向電磁石２２では、磁場を時間的に変化させ、磁場が増大する位相条件下で、加速中の荷電粒子ビームを所定の軌道に維持するようにしているので、最大繰り返し周波数は１０〜１００Ｈｚが限界であり、ビームデューティー（単位時間あたりビームが出射する時間）は１％以下に限られるが、図１２に示す加速器では、荷電粒子ビームの軌道を規定するための偏向電磁石２２の磁場を荷電粒子ビーム軌道の径方向に変化させ、時間的には一定として荷電粒子ビームを所定の軌道に維持するようにしたので、繰り返し周波数１０ｋＨｚ程度までの向上が可能となり、ビームデューティーを１０％以上に向上することが出来る。例えば、繰り返し周波数１ｋＨｚ、ビーム時間幅１００μｓ（ビームデューティー：１０％）が可能である。
【００５７】
このように、加速される荷電粒子ビームに関し、加速の初期は内側の軌道を、加速の終期は外側の軌道を周回させることで、ビーム閉じ込めを行なっており、荷電粒子ビームの加速は磁心４中の磁束密度変化に起因する誘導電場により行なうので、軌道を周回する多数のビームを一度に加速でき、大ビーム電流が得られるという特徴がある。
【００５８】
このように、本実施の形態による荷電粒子ビーム加速器では、ビーム電流を増大するために加速電圧を高電圧化しビームデューティーを増大させると、磁心４損失増大の結果発熱量が増大するという問題があるが、上記実施の形態１〜７のうちの何れかに記載された荷電粒子ビーム加速装置を用いており、冷却容器１は冷却効率が高く磁心４を十分冷却することができる。その結果、従来並みのビーム電流であれば冷却容器および磁心の小型化による小型加速器が実現できる、あるいは、冷却容器および磁心のサイズを従来並とすれば従来よりも大きなビーム電流が得られる加速器が実現できる、という効果がある。
【００５９】
特に、荷電粒子ビーム加速装置として高周波加速空洞と呼ばれる種類のものを用いる場合に、上記実施の形態７で説明したように、少なくとも伝熱壁を電気絶縁性材料で形成することにより、寄生静電容量が発生し高周波加速空洞のインピーダンスが低下するのを確実に防止できる。その結果、高出力電源が不要になり低出力な電源で励磁できるようになるので、電源コストを低減できるという効果がある。
【００６０】
【発明の効果】
以上のように、本発明によれば、環状の磁心または環の一部を欠いて環状に配置した磁心の中空部に荷電粒子ビームを通過させ、前記磁心内で時間変化する磁束密度に起因する誘導電場により該荷電粒子ビームを加速する装置であって、前記磁心に密着配置された伝熱壁と、間隔保持部材を介して前記伝熱壁と間隔を空けて対向配置された対向壁と、冷媒の導入口および導出口とを有し、内部を冷媒が流通する冷却容器を備えたので、冷却効率が向上し、しかも製造が容易な荷電粒子ビーム加速装置が得られる。
【００６１】
また、上記の荷電粒子ビーム加速装置と、荷電粒子ビームを周回させる偏向電磁石とを備えたので、従来並みのビーム電流であれば冷却容器および磁心の小型化による小型の荷電粒子ビーム加速器が得られる、あるいは、冷却容器および磁心のサイズを従来並とすれば、従来よりも大きなビーム電流が得られる荷電粒子ビーム加速器が得られる。
【図面の簡単な説明】
【図１】本発明の実施の形態１による荷電粒子ビーム加速装置の要部の構成を示し、（ａ）は側面図、（ｂ）は冷却容器の側から見た平面図である。
【図２】本発明の実施の形態１による荷電粒子ビーム加速装置の要部の別の構成を示す平面図である。
【図３】本発明の実施の形態２による荷電粒子ビーム加速装置の要部の構成を示す平面図である。
【図４】本発明の実施の形態３による荷電粒子ビーム加速装置の要部の構成を示す平面図である。
【図５】本発明の実施の形態４による荷電粒子ビーム加速装置の要部の構成を示す平面図である。
【図６】本発明の実施の形態４による荷電粒子ビーム加速装置の要部の別の構成を示す平面図である。
【図７】本発明の実施の形態５による荷電粒子ビーム加速装置の要部の構成を示す平面図である。
【図８】本発明の実施の形態６による荷電粒子ビーム加速装置の要部の構成を示す平面図である。
【図９】本発明の実施の形態７に係わり、寄生静電容量について説明するための図である。
【図１０】本発明の実施の形態７に係わり、寄生静電容量について説明するための図である。
【図１１】本発明の実施の形態８による荷電粒子ビーム加速器の要部の構成を示し、（ａ）は正面図、（ｂ）は（ａ）のＢ−Ｂ線での断面図、（ｃ）は（ｂ）のＣ−Ｃ線での断面図である。
【図１２】本発明の実施の形態９による荷電粒子ビーム加速器の要部の構成を示し、（ａ）は正面図、（ｂ）は（ａ）のＢ−Ｂ線での断面図である。
【符号の説明】
１冷却容器、２流路、３ａ冷媒導入口、３ｂ冷媒導出口、４磁心、１１ａ伝熱壁、１１ｂ対向壁、１１ｃ側壁、１２ガイド部材、１３間隔保持部材、２２偏向電磁石、２３真空ダクト。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a device for accelerating a charged particle beam by an induced electric field caused by a time-varying magnetic flux density in a magnetic core, and a charged particle beam accelerator using the same, and more particularly to a cooling structure for a magnetic core.
[0002]
[Prior art]
Before describing the related art, first, definitions of the charged particle beam accelerator and the charged particle beam accelerator referred to in the present invention will be described.
The charged particle beam accelerator according to the present invention refers to a portion of a so-called charged particle beam accelerator that accelerates a charged particle beam, and is a charged particle beam accelerator that is provided with a deflection magnet that orbits a charged particle beam. Defined as a particle beam accelerator.
[0003]
In other words, the charged particle beam is installed in an annular shape or a part of the ring so as to surround the trajectory of the charged particle beam. A charged particle beam accelerator including a magnetic core to be accelerated, exciting means for changing the magnetic flux density in the magnetic core with time, and means for cooling the magnetic core is called a charged particle beam accelerator.
Examples of the charged particle beam accelerator include a device generally called an acceleration core and a device called a high-frequency acceleration cavity. What is called an acceleration core consists of an exciting coil that wraps around the magnetic core and connects to a high-frequency power supply, and an exciting means that changes the magnetic flux density in the magnetic core over time. The exciting means comprises a high-frequency cavity for applying a high-frequency voltage to both ends of an annular opening provided at the center and surrounding the magnetic core.
[0004]
In the conventional charged particle beam accelerator defined as above, for example, an inner conductor and an outer conductor formed in a cylindrical shape are coaxially arranged in a space formed by the inner conductor and the outer conductor. In a ferrite-loaded high-frequency accelerating cavity in which a ferrite disk and a ferrite disk cooling plate are alternately stacked in the axial direction and are arranged in a line in the axial direction, the ferrite disk cooling plate has good heat. In a ring shape made of a conductor, a heat conduction plate having a groove formed on the outer peripheral surface thereof, and a coolant made of a good heat conductor, which is arranged in the groove of the heat conduction plate in the circumferential direction and brazed, is circulated. And a cooling pipe. Further, a semi-resonator configured by axially laminating a ferrite disk in a space formed by the inner conductor and the outer conductor, in which a cylindrical inner conductor and an outer conductor are arranged coaxially, In the ferrite-loaded high-frequency accelerating cavity arranged in the axial direction, the ferrite disk has a spiral groove formed in an end surface thereof, and a cooling pipe through which a refrigerant formed of a good heat conductor flows in the groove. (For example, see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-8-339898 (page 2-8, FIG. 1-10)
[0006]
[Problems to be solved by the invention]
Since the conventional charged particle beam accelerator is configured as described above, cooling is arranged by arranging a cooling pipe through which a refrigerant flows on the outer peripheral surface of a ring-shaped heat conducting plate installed on the side surface of the ferrite disk. In the configuration, the temperature of the central portion of the core is determined by the thermal conductivity of the ring-shaped thermal conductor. Therefore, when the calorific value is large, the central portion of the ferrite disk cannot be cooled to a sufficiently low temperature. Another problem is that it takes time and effort to form grooves on the outer peripheral surface of the heat conductive plate.
Further, in a configuration in which a spiral groove is formed on the end surface of the ferrite disk and a cooling pipe for circulating a refrigerant formed of a good heat conductor is disposed in the groove, the spiral groove is formed on the end surface of the ferrite disk. In the case of a large calorific value that requires a large amount of refrigerant to flow, it is necessary to form the partition wall portion of the refrigerant flow passage as thin as possible, but there is a limit to thinning. There is a problem.
[0007]
SUMMARY OF THE INVENTION It is an object of the present invention to provide a charged particle beam accelerator with improved cooling efficiency and easy manufacture, and a charged particle beam accelerator using the same.
[0008]
[Means for Solving the Problems]
A charged particle beam accelerator according to the present invention passes a charged particle beam through a hollow portion of an annular magnetic core or an annularly arranged magnetic core lacking a part of an annular core, and is caused by a time-varying magnetic flux density in the magnetic core. A device for accelerating the charged particle beam by an induction electric field, and a heat transfer wall closely attached to the magnetic core, and an opposing wall spaced apart from the heat transfer wall via a spacing member, It has a cooling container having an inlet and an outlet for the refrigerant and through which the refrigerant flows.
[0009]
Further, a charged particle beam accelerator according to the present invention includes the above charged particle beam accelerator and a bending electromagnet for orbiting the charged particle beam.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Embodiment 1 FIG.
1A and 1B show a configuration of a main part of a charged particle beam accelerator according to a first embodiment of the present invention, wherein FIG. 1A is a side view, and FIG. 1B is a plan view of the charged particle beam accelerator with a facing wall removed. is there.
The charged particle beam accelerator according to the present embodiment is annularly installed so as to surround the trajectory of the charged particle beam, allows the charged particle beam to pass through the hollow portion, and causes the charged particle beam to be induced by an induced electric field caused by a temporal change in magnetic flux density. A magnetic core 4 for accelerating the magnetic flux, an exciting unit for changing the magnetic flux density in the magnetic core 4 with time, and a unit for cooling the magnetic core are provided. FIG. 1 shows a configuration of a main part, and the exciting unit is not shown. . In addition, the exciting means is a charged particle beam accelerator called an acceleration core, which comprises an exciting coil connected to a high frequency power supply wound around the magnetic core, and the exciting means surrounds the magnetic core and is provided at both ends of an annular opening provided at a central portion. Any charged particle beam accelerator called a high-frequency accelerating cavity composed of a high-frequency cavity for applying a high-frequency voltage may be used.
[0011]
The charged particle beam accelerator according to the present embodiment includes a heat transfer wall 11a closely attached to the annular magnetic core 4, and an opposing wall 11b opposed to the heat transfer wall 11a at an interval via a spacing member. A cooling container 1 having a refrigerant inlet (hereinafter, referred to as a refrigerant inlet) 3a and an outlet (hereinafter, referred to as a refrigerant outlet) 3b. 11c is a side wall. The cooling container 1 is a sealed container surrounded by the heat transfer wall 11a, the opposing wall 11b, and the side wall 11c. In the present embodiment, the refrigerant inlet 3a and the refrigerant outlet 3b are located at positions opposing the side wall 11c. Are located.
Further, a guide member 12 is provided between the heat transfer wall 11a and the opposing wall 11b and forms a coolant flow path 2 from the coolant inlet 3a to the coolant outlet 3b, and the guide member 12 also serves as a spacing member. I have. In the present embodiment, the guide member 12 forms a plurality of flow paths 2.
Note that, in the drawing, arrows indicate the flow of the refrigerant.
[0012]
Hereinafter, a more specific description will be given. The cooling vessel 1 closely attached to the side surface of the annular magnetic core 4 has two flat plates (corresponding to the heat transfer wall 11a and the opposing wall 11b) and a plurality of mutually parallel partition walls (corresponding to the guide member 12). .) Is provided as a flow path 2 for cooling water (corresponding to a refrigerant).
[0013]
In the present embodiment, the heat transfer wall 11a, the opposing wall 11b, the side wall 11c, and the guide member 12 are made of copper or stainless steel, which is a good heat conductive metal, with an emphasis on heat conductivity. Between the magnetic core 4 and the cooling container 1 (that is, the heat transfer wall 11a), for example, an electrically insulating polyimide film having a thickness of about several tens of μm is interposed with an electrically insulating heat conductive grease (for example, silicon grease). And stick it together. The connection between the heat transfer wall 11a and the opposing wall 11b and the side wall 11c and the guide member 12 is performed by spot welding or an adhesive, but the guide member 12 inside the cooling vessel 1 is provided with a space between the heat transfer wall 11a and the opposing wall 11b. It is sufficient to have a function as an interval holding member for holding the pressure and a function to define the flow path 2. Therefore, all surfaces of the guide member 12 facing the heat transfer wall 11 a and the opposite wall 11 b are not necessarily completely joined. It does not have to be (that is, it does not need to be completely waterproof). Therefore, the production is easy and the cost can be kept low.
[0014]
As described above, according to the present embodiment, the structural strength of the cooling vessel 1 is given by the three-dimensional structure of the two flat plates (the heat transfer wall 1a and the opposing wall 1b) and the guide member 12 which also serves as the spacing member, so The thickness of the flat plate (heat transfer wall 1a) on the side closely contacting the magnetic core 4 can be reduced, and the cooling efficiency can be improved. That is, since the space between the refrigerant and the magnetic core 4 is a thin flat plate (heat transfer wall 1a), the magnetic core 4 can be cooled to a lower temperature than in the related art even when the calorific value is large.
Further, since the cooling container 1 in which the refrigerant flows is disposed in close contact with the magnetic core 4, the cooling area (the area of the part cooled by the refrigerant) can be increased, and the cooling efficiency is improved.
Moreover, as described above, the cooling container 1 made by spot welding or an adhesive is tightly adhered to the magnetic core 4 by sandwiching the polyimide film through the heat conductive grease. There is no need to form a groove on the surface or the end face of the ferrite disk, and cutting is not required and manufacturing is easy.
[0015]
Further, in the present embodiment, a plurality of flow paths 2 are formed, and a cooling water introduction part (corresponding to the refrigerant introduction port 3a) is provided between each guide member 12 (corresponding to each flow path 2). And a large flow rate of cooling water can be introduced, so that high cooling performance can be obtained even when the heat generation of the magnetic core 4 is large.
[0016]
In FIG. 1, a flat plate is used as the guide member 12, but as shown in FIG. 2, a corrugated plate may be used, and a shape in a cross section parallel to the heat transfer wall 11a may be corrugated.
As a result, the overall structural strength is further increased, so that the thickness of the guide member 12 can be further reduced, and the cooling efficiency can be further improved.
[0017]
In the above-described embodiment, the case where the magnetic core 4 is annular has been described, but the magnetic core may be arranged in an annular shape with a part of the ring omitted. This is the same in each of the following embodiments, although not particularly specified.
[0018]
In the above embodiment, the case where the coolant is the cooling water has been described. However, the present invention is not limited to this, and various liquids and gases can be used. This is the same in each of the following embodiments, although not particularly specified.
[0019]
Embodiment 2 FIG.
FIG. 3 is a diagram showing a configuration of a main part of the charged particle beam accelerator according to the second embodiment of the present invention, and is a plan view in which an opposing wall is removed and viewed from a cooling container side.
In the first embodiment, the guide member is provided so as to form the plurality of flow paths 2, but in the present embodiment, the guide member 12 is provided so as to form one flow path 2. ing. Other configurations are the same as in the first embodiment.
[0020]
Also in the present embodiment, the same effects as those in the first embodiment can be obtained.
Although the amount of cooling water is reduced as compared with the first embodiment, since the cooling water inlet (refrigerant inlet 3a) and the outlet (refrigerant outlet 3b) only need to be provided at one location each, the heat generated by the magnetic core 4 is reduced. Is small, the effect is that the structure of the cooling vessel 1 is simplified and the cost of the accelerator is reduced.
[0021]
Note that, as the guide member 12, a corrugated plate may be used instead of a flat plate, and the shape in a cross section parallel to the heat transfer wall 11a may be a corrugated shape. This further increases the overall structural strength. As in the first embodiment, the thickness can be reduced and the cooling efficiency can be further improved.
[0022]
Embodiment 3 FIG.
FIG. 4 is a diagram showing a configuration of a main part of a charged particle beam accelerator according to a third embodiment of the present invention, and is a plan view in which an opposing wall is removed and viewed from a cooling vessel side.
In the second embodiment, the guide member 12 is installed so as to form a single flow path 2 that is folded back. However, in the present embodiment, the guide member 12 is a single spiral flow path. 2 are formed. Other configurations are the same as those of the second embodiment.
[0023]
Also in the present embodiment, the same effect as that of the second embodiment can be obtained.
In general, the heat generated by the magnetic core 4 is large at the central portion of the magnetic core 4, but the cooling vessel 1 according to the present embodiment directs the cooling water outward from the central portion of the magnetic core 4 as shown by an arrow in FIG. Since the flow can be performed, the cooling efficiency of the magnetic core 4 is improved as compared with the second embodiment, and as a result, the overall cooling efficiency of the cooling container 1 is improved. Therefore, there is an effect that the size and cost of the cooling device for supplying the cooling water to the cooling container 1 can be reduced.
[0024]
Note that, as the guide member 12, a corrugated plate may be used instead of a flat plate, and the shape in a cross section parallel to the heat transfer wall 11a may be a corrugated shape. This further increases the overall structural strength. As in the first embodiment, the thickness can be reduced and the cooling efficiency can be further improved.
[0025]
Embodiment 4 FIG.
FIG. 5 is a diagram showing a configuration of a main part of a charged particle beam accelerator according to Embodiment 4 of the present invention, and is a plan view of a cooling container as viewed from a side of an opposing wall.
In the first embodiment, the refrigerant inlet 3a and the refrigerant outlet 3b are arranged at positions facing the side wall 11c. However, in the present embodiment, the plurality of flow paths 2 are formed radially. The refrigerant inlet 3a of each flow path 2 is provided at the center of the opposing wall 11b, and the refrigerant outlet 3b of each flow path 2 is provided at the peripheral edge of the opposing wall 11b. Other configurations are the same as in the first embodiment.
[0026]
Also in the present embodiment, the same effects as those in the first embodiment can be obtained.
Further, the refrigerant inlet 3a and the refrigerant outlet 3b are provided in the opposed wall 11b (provided so that the refrigerant can be introduced and taken out perpendicularly to the heat transfer wall), so that the area of the hollow portion of the cooling vessel 1 can be widened. Therefore, if the size of the electromagnets installed in the hollow portion is the same, the circumference of the magnetic core and the cooling vessel can be shortened, that is, the size can be reduced.
Normally, the heat generated by the magnetic core 4 is large at the center of the magnetic core 4. However, in the cooling vessel 1 according to the present embodiment, since the cooling water 3 is introduced from the center of the magnetic core 4, it is effective when the heat generated by the magnetic core 4 is large. There is an effect that the cooling performance is further improved as compared with the first embodiment.
Further, as compared with the third embodiment in which cooling is performed from the center of the magnetic core 4 by one flow path 2, the plurality of flow paths 2 are provided in the present embodiment, so that the cooling capacity is further increased. As a result, it is possible to increase the acceleration voltage, in which the loss of the magnetic core 4 increases, and when incorporated in a charged particle beam accelerator, there is an effect that the beam current can be increased.
[0027]
In FIG. 5, a flat plate is used as the guide member 12, but as shown in FIG. 6, a corrugated plate is used, and a shape in a cross section parallel to a heat transfer wall (not shown in FIG. 6) is used. It may have a wave shape.
As a result, the overall structural strength is further increased, so that the thickness of the guide member 12 can be further reduced, and the cooling efficiency can be further improved.
[0028]
5 and 6, an example is shown in which both the refrigerant inlet 3a and the refrigerant outlet 3b are provided on the opposing wall 11b. However, depending on the shapes of the magnetic core 4 and the cooling vessel 1, only one of the opposing walls may be provided. 11b, or at least one of the refrigerant inlet 3a and the refrigerant outlet 3b may be provided on a heat transfer wall (not shown in FIGS. 5 and 6).
[0029]
Embodiment 5 FIG.
FIG. 7 is a diagram showing a configuration of a main part of a charged particle beam accelerator according to Embodiment 5 of the present invention, and is a plan view seen from a cooling container side.
In the first embodiment, the refrigerant inlet 3a and the refrigerant outlet 3b are arranged at positions facing the side wall 11c. However, in the present embodiment, the refrigerant inlet 3a and the refrigerant outlet 3b are arranged at one position (one side surface) of the side wall 11c. is set up. Other configurations are the same as in the first embodiment.
[0030]
Also in the present embodiment, the same effects as those in the first embodiment can be obtained.
Although not as large as in the first embodiment, the amount of cooling water can be made larger than in the second and third embodiments, and the location of the water supply / drain port (the refrigerant inlet 3a and the refrigerant outlet 3b) is located on one side of the side wall 11c. This is advantageous in that the cooling system can be reduced in size and cost.
[0031]
Note that, as the guide member 12, a corrugated plate may be used instead of a flat plate, and the shape in a cross section parallel to the heat transfer wall (not shown in FIG. 7) may be a corrugated shape. Since the height is further increased, the thickness of the guide member 12 can be further reduced, and the cooling efficiency can be further improved, as in the case of the first embodiment.
[0032]
Embodiment 6 FIG.
FIG. 8 is a diagram showing a configuration of a main part of a charged particle beam accelerator according to a sixth embodiment of the present invention, and is a plan view in which an opposing wall is removed and viewed from a cooling container side.
In each of the above-described embodiments, the case has been described in which the guide member 12 that forms the flow path 2 of the refrigerant from the refrigerant inlet 3a to the refrigerant outlet 3b is provided, and the guide member 12 also functions as the spacing member. In the embodiment, the guide member 12 is not provided, but the spacing member 13 is provided. Other configurations are the same as those of the first embodiment, and therefore, the points that are different from the first embodiment will be mainly described below.
[0033]
Hereinafter, a more specific description will be given. In the present embodiment, the cooling vessel 1 has a column (corresponding to the spacing member 13) between two flat plates corresponding to the heat transfer wall 11a and the opposing wall (not shown in FIG. 8). It is installed to keep the shape of the cooling vessel 1. The material of the cooling vessel 1 and the column (spacing member 13) is, for example, copper or stainless steel as a good heat conducting material. Connection is made by spot welding or the like. The flat plate (corresponding to the side wall 11c) is welded to the peripheral ends of the two flat plates (the heat transfer wall 11a and the opposing wall) to secure the flow path 2. The refrigerant inlet 3a and the refrigerant outlet 3b for introducing and discharging the cooling water to and from the cooling container 1 are provided at opposing positions on the side wall 11c with a cross-sectional area as far as the capacity of the cooling device for supplying the cooling water to the cooling container 1 allows. , Increasing the cooling efficiency.
[0034]
In addition, the thickness of the cylinder (the spacing member 13), the arrangement interval, and the like are appropriately determined according to the shape of the cooling vessel 1, the pressure of the refrigerant, and the like.
[0035]
Also in the present embodiment, the same effects as those in the first embodiment can be obtained.
Further, since the flow rate of the cooling water can be maximized and the cooling efficiency can be improved, there is an effect that the size and cost of the cooling device that supplies the cooling water to the cooling container 1 can be reduced.
[0036]
It is needless to say that the spacing member 13 is not limited to a cylinder, but may be another shape such as a prism or an L-shaped pillar.
[0037]
Further, the spacing member 13 and the guide member 12 may be mixed.
Further, a part of the guide member 12 is fixed to both the heat transfer wall 11a and the opposing wall, and also serves as the spacing member 13, and the other part is located between at least one of the heat transfer wall 11a and the opposing wall. A configuration in which a gap is provided may be used.
[0038]
Embodiment 7 FIG.
The charged particle beam accelerator according to the present embodiment is annularly installed so as to surround the trajectory of the charged particle beam, allows the charged particle beam to pass through the hollow portion, and causes the charged particle beam to be induced by an induced electric field caused by a temporal change in magnetic flux density. A magnetic core 4 for accelerating the magnetic flux, an exciting means for changing the magnetic flux density in the magnetic core 4 with time, and a means for cooling the magnetic core. The exciting means is provided with high-frequency waves at both ends of an annular opening surrounding the magnetic core and provided at the center. This is a charged particle beam accelerator called a high-frequency accelerating cavity composed of a high-frequency cavity for applying a voltage.
[0039]
In each of the above embodiments, the cooling container 1 (the heat transfer wall 11a, the opposing wall 11b, the side wall 11c, the guide member 12, and the spacing member 13) is made of a material with an emphasis on thermal conductivity in order to enhance cooling efficiency. In this embodiment, the cooling container 1 is made of, for example, engineering plastic (for example, Kapton, MC nylon, etc.), FRP, TiN, or alumina. It is made of a suitable electrically insulating material to avoid the problem of parasitic capacitance (to be described in detail later).
[0040]
In this case, the above-described electrically insulating material has lower thermal conductivity than the good thermal conductive metal, but as described in the first embodiment, the heat transfer wall 1a, the opposing wall 1b, and the spacing member ( The three-dimensional structure provided by the guide member 12) increases the structural strength of the cooling vessel 1, so that the thickness of the heat transfer wall 1a on the side closely contacting with the magnetic core 4 can be reduced. Sufficient cooling performance can be obtained even if the above-mentioned electric insulating material is replaced.
[0041]
Hereinafter, the parasitic capacitance will be described. When the cooling vessel 1 made of an electric conductor is installed on both sides of the magnetic core 4 in order to increase the cooling efficiency of the magnetic core 4, parasitic capacitance is generated and the impedance of the high-frequency acceleration cavity is reduced. Since a decrease in impedance increases a power supply load, a high output power supply is required, and there is a problem that it becomes difficult to manufacture an excitation power supply.
[0042]
The above problem will be described in more detail with reference to FIGS. FIG. 9 shows only one cross section of the annular magnetic core and the cooling vessel. The normal magnetic core 4 is manufactured by applying and winding an insulating film on a conductive amorphous sheet so as to suppress eddy current loss generated in a closed loop surrounding magnetic flux. Therefore, the core 4 has no conductivity in the winding direction (stacking direction), but has conductivity in the thickness direction.
In this case, if the cooling vessels 1 are installed on both sides of the magnetic core 4 in order to increase the cooling efficiency, an electric insulating layer 19 (an electrically insulating polyimide film and a heat Since conductive grease is interposed, a capacitor is formed, which is equivalent to inserting a capacitance (parasitic capacitance) C in parallel with the high-frequency accelerating cavity. When represented by, the result is as shown in FIG. Here, when the time change of the magnetic flux density B occurs in a direction perpendicular to the paper surface as shown in FIG. 9, a high-frequency induced electromotive force is generated in the direction shown by the arrow in FIG. In addition, since a current path exists for the high-frequency induced electromotive force, a problem of a decrease in impedance occurs.
[0043]
The heat transfer wall 1a of the cooling vessel 1 has the greatest effect on the capacitance C. However, the cooling vessel 1 described in each of the above embodiments has a heat transfer wall 1a and an opposing wall 1b. Since the structural strength of the cooling vessel 1 is given by the three-dimensional structure of the space holding member 13 (or the guide member 12 also serving as the space holding member), the thickness of the heat transfer wall 1a on the side closely contacting the magnetic core 4 can be reduced. Even when the cooling container 1 is made of a good heat conductive metal as in the embodiment, the capacitance C is not so large, but as in the present embodiment, the cooling container 1 is made of an electrically insulating material. In this case, it is possible to more reliably prevent the problem of impedance decrease due to the influence of the capacitance (parasitic capacitance) C.
[0044]
It should be noted that only the heat transfer wall 1a having the largest effect on the capacitance C in the cooling container 1 may be formed of an electrically insulating material, and in this case, the same effect is obtained.
[0045]
Embodiment 8 FIG.
11A and 11B show a configuration of a main part of a charged particle beam accelerator according to Embodiment 8 of the present invention, wherein FIG. 11A is a front view, FIG. 11B is a cross-sectional view taken along line BB of FIG. FIG. 3B is a cross-sectional view taken along line CC of FIG. However, (c) shows a portion of the high-frequency cavity in the cross-sectional view taken along line CC of (b).
The charged particle beam accelerator according to this embodiment is the same as the charged particle beam accelerator described in any of the above embodiments, and the magnetic field for defining the trajectory of the charged particle beam changes with time to change the charged particle beam. And a bending electromagnet for making the orbit rotate.
[0046]
More specifically, the charged particle beam accelerator according to the present embodiment includes a magnetic core 4 that is installed so as to surround the trajectory of the charged particle beam and accelerates the charged particle beam by an induction electric field caused by a temporal change in magnetic flux density. A high-frequency cavity 20 to which a high-frequency voltage is applied by an excitation power supply 21 at both ends of an annular opening provided at the center of the surroundings, and a high-frequency accelerating cavity (a charged particle beam accelerating device) comprising the cooling vessel 1 installed on the side of the magnetic core 4 And a vacuum duct 23 for maintaining the inside of the vacuum and rotating the charged particle beam, and a vacuum duct for maintaining the trajectory of the charged particle beam in the vacuum duct 23 (that is, rotating the charged particle beam). A plurality of bending electromagnets 22 provided so as to sandwich the electron beam 23; an injector (not shown) for injecting a charged particle beam into the vacuum duct 23; Mainly constituted from the beam outlet device taken as particle beams (not shown).
The vacuum duct 23 is provided with an electrically insulating gap at a position surrounded by the magnetic core 4 and generates an accelerating electric field at this position.
[0047]
Next, the operation will be described. A charged particle beam is emitted from a beam injector (not shown) and introduced into the vacuum duct 23. At this time, the excitation frequency of the excitation power supply 21 is changed in synchronization with the rotation of the introduced charged particle beam so as to repeatedly accelerate the charged particle beam in one direction. The path of the accelerated charged particle beam is bent by the bending electromagnet 22, orbits (substantially circularly moves) in the annular vacuum duct 23, and is continuously accelerated while the voltage of the excitation power supply 21 is applied. At this time, the magnetic field by the bending electromagnet 22 is increased in accordance with the acceleration to maintain the orbit of the charged particle beam (the magnetic field for defining the orbit of the charged particle beam changes with time). After that, when a predetermined charged particle beam energy is reached, extraction is performed by a beam emitting device (not shown).
[0048]
Although FIG. 11 shows a case where a charged particle beam accelerator of a type called a high-frequency acceleration cavity is used, the invention is not limited to this, and a type called an acceleration core may be used.
[0049]
As described above, the charged particle beam accelerator according to the present embodiment uses the charged particle beam accelerator described in any one of Embodiments 1 to 7, and the cooling vessel 1 has high cooling efficiency. In addition, the size and cost of the magnetic core 4 can be reduced. As a result, there is an effect that the charged particle beam accelerator can be reduced in size and cost.
[0050]
In particular, when a charged particle beam accelerator of a type called a high-frequency accelerating cavity is used, as described in the seventh embodiment, at least the heat transfer wall is formed of an electrically insulating material, so that a parasitic electrostatic It is possible to reliably prevent the occurrence of capacitance and a decrease in the impedance of the high-frequency acceleration cavity. As a result, a high-output power supply is not required, and excitation can be performed with a low-output power supply, which has the effect of reducing power supply costs.
[0051]
Embodiment 9 FIG.
FIG. 12 shows a configuration of a main part of a charged particle beam accelerator according to a ninth embodiment of the present invention, where (a) is a front view and (b) is a cross-sectional view taken along line BB of (a).
The charged particle beam accelerator according to the present embodiment uses the charged particle beam accelerator described in any of the above embodiments and a magnetic field for defining the trajectory of the charged particle beam, A deflection electromagnet is provided that changes monotonically in the direction in which the diameter increases, and circulates the charged particle beam while keeping the time constant.
[0052]
More specifically, the charged particle beam accelerator (betatron accelerator) according to the present embodiment is installed so as to surround the trajectory of the charged particle beam and accelerates the charged particle beam by an induced electric field caused by a temporal change in magnetic flux density. 4. An acceleration core (corresponding to a charged particle beam accelerator) comprising an exciting coil 24 wound around the magnetic core 4 and connected to a magnetic core exciting power supply 25 (high-frequency power supply), and the cooling vessel 1 installed on the side of the magnetic core 4. A vacuum duct 23 that keeps the inside vacuum and circulates the charged particle beam; and a vacuum duct 23 that sandwiches the vacuum duct 23 in order to maintain the trajectory of the charged particle beam in the vacuum duct 23 (that is, circulate the charged particle beam). A plurality of bending electromagnets 22, an injector (not shown) for injecting a charged particle beam into the vacuum duct 23, and a charged particle beam Mainly constituted from the beam extraction device (not shown) out.
[0053]
Next, the operation will be described. A charged particle beam is emitted from a beam injector (not shown), and introduction into the annular vacuum duct 23 is started from the center. At this point, if the voltage of the magnetic core excitation power supply 25 is set to a high voltage, an induced electric field equal to the excitation voltage is generated on the trajectory of the charged particle beam surrounding the cross section of the magnetic core 4, and the charged particle beam starts to accelerate. The accelerated charged particle beam is deflected by the bending electromagnet 22, orbits (substantially circularly moves) in the annular vacuum duct 23, and is continuously accelerated while the voltage of the magnetic core excitation power supply 25 is applied. . The magnetic field generated by the bending electromagnet 22 is designed so that the radial direction of the orbit of the charged particle beam monotonically increases outward (that is, monotonically increases in a direction in which the diameter of the orbit of the charged particle beam increases). The charged particle beam can be confined in the vacuum duct 23 without greatly expanding the trajectory of the charged particle. When the charged particle beam energy reaches a predetermined value, extraction is performed by a beam emitting device (not shown) installed at the outer edge of the annular vacuum duct 23.
[0054]
FIG. 12 shows a case where a charged particle beam accelerator of a type called an acceleration core is used. However, the present invention is not limited to this, and a type called a high-frequency acceleration cavity may be used.
[0055]
In the above example, the magnetic field generated by the bending electromagnet 22 monotonically increases outward in the radial direction of the charged particle beam orbit (that is, monotonically increases in a direction in which the diameter of the charged particle beam orbit increases). May monotonically increase toward the inside in the radial direction (that is, monotonically decrease in a direction in which the diameter of the charged particle beam orbit increases). In this case, contrary to the above example, the charged particle beam is drawn inward in the radial direction as the energy increases. Therefore, a beam is incident from the outside of the annular vacuum duct 23, and the beam is extracted from the inside.
[0056]
In the bending electromagnet 22 of a normal betatron accelerator, the magnetic field is changed with time so that the charged particle beam during acceleration is maintained in a predetermined orbit under a phase condition in which the magnetic field increases. Has a limit of 10 to 100 Hz, and the beam duty (time of beam emission per unit time) is limited to 1% or less. However, in the accelerator shown in FIG. 12, the bending electromagnet 22 for defining the trajectory of the charged particle beam is used. Is changed in the radial direction of the trajectory of the charged particle beam, and the charged particle beam is maintained at a predetermined trajectory while keeping the time constant. Therefore, the repetition frequency can be improved to about 10 kHz, and the beam duty can be reduced to 10 kHz. % Or more. For example, a repetition frequency of 1 kHz and a beam time width of 100 μs (beam duty: 10%) are possible.
[0057]
As described above, with respect to the charged particle beam to be accelerated, the beam is confined by orbiting the inner orbit at the beginning of the acceleration and the orbit at the end of the acceleration, and the acceleration of the charged particle beam is performed in the magnetic core 4. Since the induction is performed by an induction electric field caused by a change in magnetic flux density, a large number of beams orbiting the orbit can be accelerated at a time, and a large beam current can be obtained.
[0058]
As described above, in the charged particle beam accelerator according to the present embodiment, when the acceleration voltage is increased to increase the beam current and the beam duty is increased, there is a problem that the calorific value increases as a result of an increase in the loss of the magnetic core 4. However, the charged particle beam accelerator described in any of Embodiments 1 to 7 is used, and the cooling container 1 has high cooling efficiency and can sufficiently cool the magnetic core 4. As a result, a compact accelerator can be realized by reducing the size of the cooling vessel and the magnetic core if the beam current is about the same as the conventional one, or an accelerator that can obtain a larger beam current than the conventional one if the size of the cooling vessel and the core are the same as the conventional one. There is an effect that it can be realized.
[0059]
In particular, when a charged particle beam accelerator of a type called a high-frequency accelerating cavity is used, as described in the seventh embodiment, at least the heat transfer wall is formed of an electrically insulating material, so that a parasitic electrostatic It is possible to reliably prevent the occurrence of capacitance and a decrease in the impedance of the high-frequency acceleration cavity. As a result, a high-output power supply is not required, and excitation can be performed with a low-output power supply, which has the effect of reducing power supply costs.
[0060]
【The invention's effect】
As described above, according to the present invention, the charged particle beam is passed through the hollow portion of the annular magnetic core or the circularly arranged magnetic core lacking a part of the annular shape, and is caused by the time-varying magnetic flux density in the magnetic core. A device for accelerating the charged particle beam by an induction electric field, and a heat transfer wall closely attached to the magnetic core, and an opposing wall spaced apart from the heat transfer wall via a spacing member, Since a cooling container having an inlet and an outlet for the refrigerant and through which the refrigerant flows is provided, a charged particle beam accelerator with improved cooling efficiency and easy manufacture can be obtained.
[0061]
In addition, since the above-described charged particle beam accelerator and the deflection electromagnet for orbiting the charged particle beam are provided, a small charged particle beam accelerator can be obtained by reducing the size of the cooling vessel and the magnetic core if the beam current is at the same level as the conventional one. Alternatively, if the sizes of the cooling vessel and the magnetic core are made equal to those of the conventional one, a charged particle beam accelerator capable of obtaining a larger beam current than before can be obtained.
[Brief description of the drawings]
FIG. 1 shows a configuration of a main part of a charged particle beam accelerator according to a first embodiment of the present invention, where (a) is a side view and (b) is a plan view seen from a cooling vessel side.
FIG. 2 is a plan view showing another configuration of a main part of the charged particle beam accelerator according to the first embodiment of the present invention.
FIG. 3 is a plan view showing a configuration of a main part of a charged particle beam accelerator according to a second embodiment of the present invention.
FIG. 4 is a plan view showing a configuration of a main part of a charged particle beam accelerator according to a third embodiment of the present invention.
FIG. 5 is a plan view showing a configuration of a main part of a charged particle beam accelerator according to a fourth embodiment of the present invention.
FIG. 6 is a plan view showing another configuration of a main part of the charged particle beam accelerator according to Embodiment 4 of the present invention.
FIG. 7 is a plan view showing a configuration of a main part of a charged particle beam accelerator according to a fifth embodiment of the present invention.
FIG. 8 is a plan view showing a configuration of a main part of a charged particle beam accelerator according to a sixth embodiment of the present invention.
FIG. 9 is a diagram for explaining a parasitic capacitance according to the seventh embodiment of the present invention.
FIG. 10 is a diagram illustrating a parasitic capacitance according to the seventh embodiment of the present invention.
11A and 11B show a configuration of a main part of a charged particle beam accelerator according to an eighth embodiment of the present invention, where FIG. 11A is a front view, FIG. 11B is a cross-sectional view taken along line BB of FIG. () Is a cross-sectional view taken along line CC in (b).
12 shows a configuration of a main part of a charged particle beam accelerator according to a ninth embodiment of the present invention, in which (a) is a front view and (b) is a cross-sectional view taken along line BB of (a).
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Cooling container, 2 flow paths, 3a refrigerant inlet, 3b refrigerant outlet, 4 cores, 11a heat transfer wall, 11b opposing wall, 11c side wall, 12 guide member, 13 interval holding member, 22 deflection electromagnet, 23 vacuum duct.

Claims

An apparatus for passing a charged particle beam through a hollow portion of an annular magnetic core or an annularly arranged magnetic core lacking a part of the ring and accelerating the charged particle beam by an induced electric field caused by a time-varying magnetic flux density in the magnetic core And
A heat transfer wall closely attached to the magnetic core, an opposing wall arranged opposite to the heat transfer wall at an interval via a spacing member, and a refrigerant inlet and outlet, and the inside of the refrigerant A charged particle beam accelerator, comprising: a cooling vessel through which the gas flows.

2. The charged particle beam accelerator according to claim 1, further comprising a guide member disposed between the heat transfer wall and the facing wall, the guide member forming a flow path of the refrigerant from the inlet to the outlet of the refrigerant.

3. The charged particle beam accelerator according to claim 2, wherein the guide member also serves as a spacing member.

The charged particle beam accelerator according to claim 2, wherein the guide member has a wavy shape in a cross section parallel to the heat transfer wall.

The charged particle beam accelerator according to claim 2, wherein the guide member forms a plurality of flow paths.

The charged particle beam accelerator according to claim 5, wherein the plurality of flow paths are formed radially.

The charged particle beam accelerator according to claim 2, wherein the guide member forms a spiral flow path.

The charged particle beam accelerator according to claim 2, wherein the guide member forms an annular flow path.

The charged particle beam accelerator according to claim 1, wherein at least one of the inlet and the outlet of the refrigerant is provided on the heat transfer wall or the opposing wall.

The charged particle beam accelerator according to claim 1, wherein the heat transfer wall is formed of an electrically insulating material.

A charged particle beam accelerator comprising the charged particle beam accelerator according to any one of claims 1 to 10, and a deflection electromagnet for rotating the charged particle beam.

The charged particle beam accelerator according to claim 11, wherein the bending electromagnet changes a magnetic field for defining a trajectory of the charged particle beam with time.

The bending electromagnet changes the magnetic field for defining the trajectory of the charged particle beam in a monotonically increasing or decreasing manner in a direction in which the diameter of the charged particle beam orbit increases, and is constant in time. The charged particle beam accelerator according to claim 11, wherein: