JP4085176B2 - Electron beam trajectory correction apparatus and trajectory correction method - Google Patents

Description

【００７２】
なお、蛇足ながら、変数Ｘ（１）は、上記第２で、第１のステアリング電磁石６０Ａに流した所定の励磁電流量ＩＳ（１）との比を、同様に、変数Ｘ（２）は、上記第３で、第２のステアリング電磁石６０Ｂに流した所定の励磁電流量ＩＳ（２）との比を表している（以下同じ）。
また、式（１）では、ステアリング電磁石６０Ａ、６０Ｂによる偏向角は実際は極めて小さいものであるので、励磁電流量とそれに伴う変位は比例関係にあるとしている（以下同様）。
【００７３】
第５に、第２の四重極電磁石６０Ｂについて、第２の四重極電磁石６０Ｂの励磁電流量を所定量変化させても、ビームポジションモニタ９２における電子ビームの位置が変化しないという条件を基にして、第１、第２のステアリング電磁石の夫々の励磁電流量を変数Ｘ（１）・ＩＳ（１）、Ｘ（２）・ＩＳ（２）とする第２の方程式を、演算装置１２において作成する（ＳＴ６）。
【００７４】
この第２の方程式は次式で与えられる。

【００７５】
第６に、図３のＳＴ７に示すように、上記第１、第２の方程式、式（１）、式（２）を連立方程式として、Ｘ（１）、Ｘ（２）の解を求め、第１、第２のステアリング電磁石６０Ａ、６０Ｂの励磁電流量を演算装置１２により算出する。
【００７６】
第７に、第６で算出した第１、第２のステアリング電磁石の励磁電流量に基づいて、第１、第２のステアリング電磁石６０Ａ、６０Ｂの励磁電流量Ｘ（１）・ＩＳ（１）、Ｘ（２）・ＩＳ（２）を、ステアリング電流制御装置６４Ａ、６４Ｂにより制御する（ＳＴ８）。
【００７７】
上述したように、電子ビームが四重極電磁石７０Ａ、７０Ｂの磁場中心を通過すれば、四重極電磁石７０Ａ、７０Ｂの励磁電流量を変化させても電子ビームのポジションモニタ９２において変位しなくなるので、このようにステアリング電磁石６０Ａ、６０Ｂの励磁電流量を制御することにより、電子ビームが双方の四重極電磁石７０Ａ、７０Ｂの中心を通るように補正するようにすることができ、従って、これにより本発明の電子ビームの軌道補正方法が終了する（ＳＴ９）。
【００７８】
なお、上記説明において、第１乃至第３で示した変位の測定は、夫々独立に行えるものであり、必ずしもこの順番で行わなければならない訳ではない。即ち、これらは補正方法の手順を説明するために便宜的に付したものであり、例えば、第２、第３、第１の順に変位の測定を行うようにしても良い。
【００７９】
上述したように、本発明の軌道補正装置１０Ａを用いると、簡易に電子ビームの軌道を四重極電磁石の中心を通過するように電子ビームの位置を補正することができ高品位の電子蓄積リングとすることが可能になる。
【００８０】
また、実際に電子ビームを蓄積した状態で軌道補正を行っているので、電子蓄積リングの運転中に四重極電磁石の磁場中心位置がずれることがあっても、簡単にそれに対応した軌道の補正ができる。
【００８１】
更に、四重極電磁石の磁場中心を通るように電子ビームの軌道を補正できるので、ビームポジションモニタの校正誤差、据え付け誤差などが軌道補正に影響を与えない。
【００８２】
第２の実施の形態：
第１の実施の形態では、本発明の骨格を理解する便を図るために、四重極電磁石の数を２、ステアリング電磁石の数を２とする特殊な場合で説明したが、本発明の第２の実施の形態では、四重極電磁石の数をｎ個、ステアリング電磁石の数をｍ個とする、一般化した場合の例についてであり、この第２の実施の形態について図４を用いて説明をする。
【００８３】
図４は、本発明の電子ビームの軌道補正装置の第２の実施の形態の構成を示すブロック図である。
本実施の形態における軌道補正装置１０Ｂは、図１に示す軌道補正装置１０Ａとは、主要構成においては本質的な相違点はなく、四重極電磁石をｎ個、ステアリング電磁石をｍ個と一般的に拡張した場合に対応したものである。
【００８４】
即ち、本実施の形態における電子ビームの軌道補正装置１０Ｂは、図４に示すように、先ず、ステアリング系では、ｍ個のステアリング電磁石６０Ａ１〜６０Ａｍと、このステアリング電磁石６０Ａ１〜６０Ａｍに励磁電流を供給するステアリング電磁石用電源６２Ａ１〜６２Ａｍと、このステアリング電磁石用電源６２Ａ１〜６２Ａｍからステアリング電磁石６０Ａ１〜６０Ａｍに供給される励磁電流を制御するステアリング電流制御装置６４Ａ１〜６４Ａｍとを備えている。
【００８５】
また、四重極電磁石７０Ａ１〜７０Ａｍに関連する四重極電磁石系では、四重極電磁石用電源７２と、この電源７２からの電流を夫々個別に変化させることができる分流器７４とを備えている。
また、それ以外の構成要素としては、図４に示すように、電子ビームの位置を検出するビームポジションモニタ９２と、ステアリング電磁石６０Ａ１〜６０Ａｍに通電すべき励磁電流量を算出する演算装置１２とを備えている。
【００８６】
以上の構成において、本実施の形態の電子ビームの軌道補正装置１０Ｂの基本動作及び軌道補正方法について、図４を用いて説明する。
本実施の形態における軌道補正装置１０Ｂの基本動作は、第１の実施の形態と本質的な相違点はなく、四重極電磁石をｎ個、ステアリング電磁石をｍ個と一般的に拡張した場合に対応している。
【００８７】
第１に、総てのステアリング電磁石を励磁させない状態で、第ｐの四重極電磁石の励磁電流量を単独で所定量変化させた場合のビームポジションモニタにおける電子ビームの変位を検出し、この変位をＺ（ｐ，０）とする。
ここでは勿論、ｐは１≦ｐ≦ｎの整数である。
整数ｐを１からｎまで順次変化させることにより、第１乃至第ｎの四重極電磁石７０Ａ１〜７０Ａｎの変位が、夫々Ｚ（１，０）〜Ｚ（ｎ，０）と求めることができる。
【００８８】
第２に、第ｑのステアリング電磁石６０Ａｑに単独で励磁電流を所定量供給した状態で、第ｐの四重極電磁石７０Ａｐの励磁電流量を単独で所定量変化させた場合のビームポジションモニタにおける電子ビームの変位を検出し、この変位をＺ（ｐ，ｑ）とする。
ここでは勿論、ｑは１≦ｑ≦ｍの整数である。
【００８９】
ここで、整数ｑを１からｍまで順次変化させることにより、第ｑのステアリング電磁石６０Ａｑに単独で励磁電流を所定量供給した第ｐの四重極電磁石７０Ａｐの励磁電流を所定両辺化させた場合におけるビームポジションモニタでの変位が、夫々Ｚ（ｐ，１）〜Ｚ（ｐ，ｍ）と求めることができる。
【００９０】
なお、各四重極電磁石７０Ａ１〜７０Ａｍの励磁電流量の変化量は、整数ｑを１からｍまで順次変化させる過程において、同一の四重極電磁石７０Ａ１〜７０Ａｍについては、同一の変化量であるものとする。
【００９１】
更に、この手順を、整数ｐを１からｎまで順次変化させながら繰り返すことにより、第１乃至第ｎの四重極電磁石７０Ａ１〜７０Ａｍの変位が、夫々Ｚ（１，１）〜Ｚ（ｎ，ｍ）のｍ・ｎ通りの変位を算出できる。
【００９２】
第３に、第ｐの四重極電磁石について、第ｐの四重極電磁石の励磁電流量を所定量変化させても、ビームポジションモニタにおける電子ビームの位置が変化しないという条件を基にして、第ｑのステアリング電磁石の夫々の励磁電流量を変数とする第ｐの方程式を作成する。
ｐを１からｎまで順次変化させることにより、ｎ個の方程式を演算装置１２において作成できる。
【００９３】
このｎ個の方程式は次式で与えられる。

【００９４】
第４に、上記第３で作成したｎ個の方程式を連立方程式とし、以下の方法で第１乃至第ｍのステアリング電磁石の励磁電流量の解を算出する。
【００９５】
ところで、ｎ＜ｍの場合は、連立方程式の解は不能となるので、ｎ＝ｍ又はｎ＞ｍである必要がある。
従って、第５に、ｎ＝ｍの場合は、第４の連立方程式を解くことにより算出した第１乃至第ｍのステアリング電磁石の励磁電流量に基づいて、第１乃至第ｍのステアリング電磁石の励磁電流量を制御する。
【００９６】
一方、ｎ＞ｍの場合は、第４の連立方程式を最小自乗法により最適値化して算出した第１乃至第ｍのステアリング電磁石の励磁電流量に基づいて、第１乃至第ｍのステアリング電磁石の励磁電流量を制御する。
【００９７】
これにより、本発明の軌道補正装置１０Ｂを用いると、四重極電磁石の個数をｎ、ステアリング電磁石の個数をｍと一般化した場合でも、簡易に電子ビームの軌道を四重極電磁石の磁場中心を通過するように電子ビームの軌道を補正することができ高品位の電子蓄積リングとすることが可能になる。
【００９８】
また、同様に、実際に電子ビームを蓄積した状態で軌道補正を行っているので、電子蓄積リングの運転中に四重極電磁石の磁場中心位置がずれることがあっても、簡単にそれに対応した軌道の補正ができる。
なお、上記説明において、第１、第２で示した変位の測定は、夫々独立に行えるもので、第１の実施の形態で説明したのと同様に、必ずしもこの順番に拘束されるものではないことを付記しておく。
【００９９】
本発明の電子ビームの軌道補正装置は上記各実施の形態に限定されず種々の変更が可能である。
例えば、上記各実施の形態では、ビームポジションモニタを１つだけ用いた場合で説明したが、ビームポジションモニタを複数個用い、これを電子蓄積リングの適当な位置に配置して、電子ビームの位置を補正するように構成しても良い。
【０１００】
この場合は、各ビームポジションモニタにおいて、上述した電子ビームの軌道補正を行うことになるが、これにより、一層精度の高い電子ビームの軌道補正が可能になり、例えば、超高精度を要求される電子蓄積リングに対応することが可能となる。
【０１０１】
【発明の効果】
（１）本発明の電子ビームの軌道補正装置は、請求項１に記載したように構成したために、簡易に電子ビームの軌道を四重極電磁石の中心を通過するように補正することができ、この結果、高品位の電子蓄積リングとすることが可能になる。
（２）また、実際に電子ビームを使って四重極電磁石の磁場中心位置を検出した補正を行っているので、電子蓄積リングの運転中に四重極電磁石の磁場中心位置がずれることがあっても、簡単にそれに対応した位置の補正ができる。
（３）更に、ビームポジションモニタの中心位置にこだわることなく、四重極電磁石の磁場中心を通るように電子ビームの軌道を補正できるので、ビームポジションモニタの校正誤差、据え付け誤差などが軌道補正に影響を与えない。
【０１０２】
（４）具体的には、請求項１に記載の電子ビームの軌道補正装置を用いた軌道補正方法は、請求項２に記載のような手順で行えばよい。
【０１０３】
（５）本発明の電子ビームの軌道補正装置は、請求項３に記載したように構成すると、ステアリング電磁石の個数をｍ個、四重極電磁石の個数をｎ個と一般化した場合にも対応が可能となる。
【０１０４】
（６）具体的には、請求項３に記載の電子ビームの軌道補正装置を用いた軌道補正方法は、請求項４に記載したような手順で行えばよい。
【０１０５】
（７）また、請求項５又は６に記載したように構成すると、電子ビームの軌道補正が一層精密に行え、超高精密を要求される電子蓄積リングに対応することが可能となる。
【図面の簡単な説明】
【図１】本発明の電子ビームの軌道補正装置の第１の実施の形態を示すブロック図である。
【図２】本発明の電子ビームの軌道補正装置の第１の実施の形態に用いる主要構成の配置を示す電子蓄積リングの平面図である。
【図３】本発明の電子ビームの軌道補正装置の第１の実施の形態の基本動作を説明するためのフローチャートである。
【図４】本発明の電子ビームの軌道補正装置の第２の実施の形態を示すブロック図である。
【図５】電子蓄積リングの基本構成を説明するための平面図である。
【図６】電子蓄積リングに用いるビームポジションモニタの構成を示す縦断面図である。
【図７】ステアリング電磁石の構成を示す縦断面図である。
【図８】ステアリング電磁石の構成を示す側面図である。
【符号の説明】
１０Ａ、１０Ｂ：電子ビームの軌道補正装置
１２：演算装置
６０：ステアリング電磁石
６２：ステアリング電磁石用電源
６４：ステアリング電流制御装置
７０：四重極電磁石
７２：四重極電磁石用電源
７４：分流器
９０Ａ、９０Ｂ：偏向電磁石
９２：ビームポジションモニタ
１００：電子蓄積リング[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a small electron storage ring for the purpose of accumulating an electron beam with a desired energy in a closed orbit and mainly generating synchrotron radiation, and in particular corrects the orbit of the accumulated electron beam. The present invention relates to a trajectory correction apparatus for the above and an electron beam trajectory correction method using the trajectory correction apparatus.
[0002]
[Prior art]
When charged particles such as electrons and ions travel in a uniform magnetic field, a circular orbit (generally a spiral orbit) is drawn by the action of a Lorentz force perpendicular to the traveling direction.
[0003]
Therefore, with a deflecting electromagnet that generates a uniform magnetic field in the vertical direction, an arc trajectory with a desired radius of curvature is drawn on a charged particle having a constant kinetic energy, and its traveling direction is bent at a desired angle. By arranging a plurality of deflection electromagnets at appropriate positions, it is possible to make charged particles circulate on a closed orbit in a horizontal plane.
[0004]
That is, in principle, electrons can be stored with a desired energy in a closed orbit in a beam duct kept in a vacuum only by a deflecting electromagnet. However, in an electron storage ring actually used, Equipment is required.
Therefore, the main configuration of the electron storage ring will be briefly described with reference to FIG.
[0005]
FIG. 5 shows a plan view of a racetrack type electron storage ring 100 as an example of the electron storage ring.
In this type of electron storage ring 100, as shown in FIG. 5, 180 degree deflection type deflecting electromagnets 90A and 90B are arranged opposite to each other, and a high vacuum (˜1 × 10 × 10) is provided by a vacuum pump (not shown).^-9The electron beam is accumulated in a circular trajectory (which may be referred to as “design trajectory” or “closed trajectory” for convenience of explanation) in the racetrack type beam duct 80 maintained at Torr).
[0006]
In FIG. 5, reference numeral 20 denotes an injector for supplying an electron beam having a constant energy to the electron storage ring 100.
According to the theory of relativity, when the kinetic energy of the particles increases, the mass increases accordingly, so the stored electrons are less likely to bend in the magnetic field.
[0007]
Therefore, in order to confine the electron beam in a fixed design trajectory, in general, the electron storage ring is not limited to the one shown in FIG. 5, and the magnetic field strength of the deflection electromagnet is adjusted in conjunction with the energy of the electron beam.
[0008]
Therefore, theoretically, any low energy electrons should be able to be accumulated by reducing the magnetic field strength of the deflecting electromagnets 90A and 90B shown in FIG.
However, if the electron energy is extremely small, the beam trajectory becomes unstable, and there is a problem that the electron beam cannot be stably accumulated.
[0009]
Therefore, the injector 20 accelerates the electrons to a certain energy, for example, the type shown in FIG.
In FIG. 5, reference numeral 22 denotes a septum electromagnet for changing the direction of the electron beam so that the electron beam provided to the electron storage ring 100 from the injector 20 is smoothly incident on the closed circular orbit. It is.
[0010]
In FIG. 5, reference numerals 70A and 70B denote quadrupole electromagnets, which excite a magnetic field with a magnetic field distribution that increases in proportion to the distance from the center with the magnetic field strength at the center being zero, The optical lens plays a role of focusing the electron beam in the same manner as the light lens collects the light.
By these quadrupole electromagnets 70A and 70B, the electron beam is accumulated in the electron storage ring 100 in a stable state without divergence from the closed orbit maintained in the vacuum in the beam duct 80.
[0011]
On the other hand, charged particles such as electrons and ions have the property of emitting electromagnetic waves in the form of bremsstrahlung when subjected to an acceleration action.
Therefore, when electrons are bent by the deflecting electromagnets 90A and 90B, synchrotron radiation (SynchronronRadiatuio: Hereinafter, it may be simply referred to as “SR”. ) Is emitted and its energy is attenuated. Therefore, unless this energy loss is always compensated, there is a problem that an electron beam cannot be stably accumulated with desired energy.
[0012]
In some cases, it is necessary to increase the energy of the accumulated electron beam to accumulate electrons with a higher energy to cope with various uses.
[0013]
In this way, the high-frequency acceleration cavity 30 shown in FIG. 5 supplies energy to the accumulated electron beam.
The high-frequency accelerating cavity 30 refers to the phase of the high-frequency voltage generated in the high-frequency accelerating cavity 30 and the electrons so that they are just accelerated when high-frequency power is applied and electrons reach the acceleration gap of the high-frequency accelerating cavity 30. It is a device that supplies energy to the stored electrons by synchronizing well with the position of.
[0014]
The number of times that the high-frequency voltage supplied to the high-frequency accelerating cavity 30 vibrates while the electron makes one round of the closed orbit in the electron storage ring 100 is called a harmonic number.
[0015]
By adjusting the length of the closed orbit and the frequency of the high frequency applied to the high frequency acceleration cavity 30 so that the harmonic number becomes an integer, the device can be devised so that energy can be supplied every time the electron passes through the high frequency acceleration cavity 30. it can.
This makes it possible to compensate for the loss of electron energy or to accelerate the electron to a desired energy after the electron is incident.
[0016]
In FIG. 5, reference numeral 50 denotes a perturbator electromagnet (or kicker electromagnet).
When the storage electrons are incident on the electron storage ring 100, they already have a certain spread, so that all the electrons do not circulate on the designed closed orbit, but the electron storage ring 100 around the designed orbit. During one round of the closed orbit, a slight vibration is caused about the closed orbit.
[0017]
This minute vibration is called betatron vibration, and the number of times that electrons oscillate during one round of the closed orbit is called betatron frequency or betatron tune, or simply tune.
[0018]
Due to this betatron oscillation, if no contrivance is applied to the electrons after the incident, the electron beam returns to the position of the incident septum electromagnet 22 and collides with the septum electromagnet 22 after making a round orbit around the closed orbit. It disappears before it accumulates on a stable design trajectory.
[0019]
Therefore, a pulse current is passed through the perturbator electromagnet 50 to instantly excite it, deflect the electron beam using the falling edge of the pulse, and form a trajectory that is deformed only at the time of incidence called the incident trajectory. Incident.
As a result, the electrons can stably circulate around the design trajectory without colliding with the septum electromagnet 22 even after incidence.
[0020]
In FIG. 5, reference numeral 92 denotes a beam position monitor, which plays a role of monitoring whether or not the electron beam is accumulated as designed on the circular closed orbit in the beam duct 80.
[0021]
An electron beam accumulation method using the electron accumulation ring 100 shown in FIG.
The electron beam accelerated to a desired energy by the injector 20 is smoothly incident on the closed orbit of the electron storage ring 100 by the septum electromagnet 22.
[0022]
Thereafter, as described above, the beam is temporarily deflected by the part beta electromagnet 50 and is stably accumulated in the closed track designed by the deflection electromagnets 90A and 90B and the quadrupole electromagnets 70A and 70B.
Further, the high-frequency accelerating cavity 30 supplements the energy loss of the accumulated electron beam and accumulates it with a constant energy, or accelerates it and accumulates it with a desired energy.
[0023]
By the way, as described above, in the electron storage ring, electrons emit synchrotron radiation (SR) in the deflecting electromagnet and lose energy, which defines an upper limit of the energy of the electron beam that can be stored. It was one cause.
In order to reduce the energy loss due to SR and increase the energy of an electron beam that can be stored, an electron storage ring that has a large curvature radius of a deflecting electromagnet and is enlarged has been developed.
[0024]
On the other hand, SR is white light of continuous spectrum with extremely high brightness and high directivity emitted in a certain horizontal plane, and an electron storage ring that actively uses this SR as a light source has been developed.
The electron storage ring 100 shown in FIG. 5 is a typical one developed mainly as a light source for SR.
[0025]
The accumulated electron beam current is large, the radius of curvature of the deflecting electromagnet is reduced in a strong magnetic field, and the critical wavelength of SR is shortened to the X-ray region, and it is particularly intended to be used as a small light source for X-ray lithography. It is said.
[0026]
Next, the beam position monitor 92 used for measuring the position of the electron beam in the electron storage ring 100 will be supplementarily described with reference to FIGS.
FIG. 6 is a longitudinal side view showing a schematic structure of the beam position monitor 92.
[0027]
The beam position monitor 92 used in the electron storage ring 100 shown in FIG. 5 is usually called a button-type beam position monitor, and is a typical monitor used in such an electron storage ring.
[0028]
The beam position monitor 92 has a structure in which four button electrodes 98A to 98D are fixed to a vacuum chamber 94 via coaxial connectors 96A to 96D, as shown in a longitudinal sectional view of FIG.
[0029]
When the electron beam passes through the vacuum chamber 94 in a direction perpendicular to the drawing, the electric charges induced in the four button electrodes 98A to 98D are detected as signals, and the position of the electron beam is prevented from proceeding with the electron beam. Without being detected, it can be detected in both the horizontal and vertical directions.
[0030]
In the case of the electron storage ring 100 shown in FIG. 5, the spot diameter of the electron beam is about (Φ˜0.6 mm), and if this button type beam position monitor type beam position monitor 92 is used, the measurement is about 10˜20 μm. With the error, the position of the electron beam can be measured.
[0031]
[Problems to be solved by the invention]
By the way, in the electron storage ring, when the electron beam is stored, it is preferable that the electron beam is stored on the designed orbit.
For example, in the case of a quadrupole electromagnet, this design trajectory is set to pass through the center of the quadrupole electromagnet. However, due to installation errors of the quadrupole electromagnet, the electron beam accumulates in the design trajectory. It is not always done.
[0032]
If the electron beam does not pass through the center of the quadrupole electromagnet, the excitation current of the quadrupole electromagnet is changed, the magnetic field intensity is changed, and the focusing force for focusing the electron beam of the quadrupole electromagnet is changed. There is a problem that the quality of the electron storage ring deteriorates because the position of the orbit of the electron beam shifts, for example, the position of light generation as a light source for X-ray lithography changes.
[0033]
Therefore, conventionally, a method has been adopted in which an electron beam deviating from the design trajectory is deflected at a desired angle by a steering electromagnet and corrected so as to go around the design trajectory.
A structure of the steering electromagnet and a method of correcting the electron beam trajectory by the steering electromagnet will be briefly described with reference to FIGS.
[0034]
FIG. 7 is a longitudinal sectional view of the steering electromagnet 60, and FIG. 8 is a side view of the steering electromagnet 60.
As shown in FIGS. 7 and 8, the steering electromagnet 60 includes an iron core 64 and exciting coils 62A to 62D wound around the iron core.
[0035]
An exciting current is supplied from a power source (not shown) to the exciting coils 62A to 62D of the steering electromagnet 60 to generate a magnetic field in the region through which the electron beam passes, and the electron beam is moved both horizontally and vertically by the action of this magnetic field. The beam position is corrected by deflecting it at a desired angle.
[0036]
At this time, the beam position monitor 92 shown in FIGS. 5 and 6 adjusts the deflection angle with the amount of exciting current while monitoring the trajectory of the electron beam, so that the orbit of the electron beam becomes exactly the designed trajectory. I was trying to adjust.
[0037]
Therefore, if the center of the beam position monitor 92 and the center positions of the quadrupole electromagnets 70A and 70B shown in FIG. 5 are strictly matched, the electron beam is moved around the center of the beam position monitor 92 by the method described above. By adjusting to pass, it is possible to pass through the center of the quadrupole electromagnets 70A and 70B.
[0038]
However, in general, it is difficult to strictly match the center position of the quadrupole electromagnet with the center position of the beam position monitor.
In particular, since the calibration of the installation of the quadrupole electromagnet and the installation of the beam position monitor has been calibrated in the so-called beam off-line that does not pass the electron beam, the center of the quadrupole electromagnet and the position of the beam position monitor have been adjusted. It is extremely difficult to match the two, and it is difficult to guarantee the quality of the electron storage ring.
[0039]
As described above, the quadrupole electromagnet is designed so that the magnetic field intensity is exactly zero at the center position.
In general, the center of the quadrupole electromagnet has a center position physically determined from the tip position of each magnetic pole of the quadrupole electromagnet and a magnetic field center where the magnetic field intensity is just zero.
Theoretically, the physical center and the magnetic field center coincide with each other, and the quadrupole electromagnet is manufactured so that both coincide with each other. However, due to various causes such as magnetic pole shape errors, the physical center and the magnetic field center are manufactured. The center may not exactly match.
[0040]
The center of the magnetic field of the quadrupole electromagnet may fluctuate slightly depending on the operation status of the electron storage ring. As described above, the physical center position of the quadrupole electromagnet and the beam position monitor can be used offline. This is always a problem in the method of correcting the trajectory of the electron beam after the alignment with.
Therefore, in order to correct the trajectory of the electron beam in accordance with the operating state of the electron storage ring, a trajectory correction method that can be executed while the electron beam is stored is required.
[0041]
The present invention solves the above-mentioned problems (problems), and an electron beam trajectory correcting apparatus capable of correcting the electron beam trajectory to an accurate design trajectory while accumulating the electron beam by a simple method, and an electron beam An object is to provide a trajectory correction method.
[0042]
[Means for Solving the Problems]
  An electron beam trajectory correcting apparatus according to the present invention is the electron beam (including positron) beam comprising a plurality of deflection electromagnets and first and second quadrupole electromagnets. In an electron storage ring that stores energy at a desired energy in a closed orbit, first and second steering electromagnets for deflecting an electron beam in a vertical direction and a horizontal direction, and an excitation current for each of the steering electromagnets. Supply power to steering electromagnet, steering current control device for controlling excitation current of each steering electromagnet, power supply for quadrupole electromagnet for excitation of each quadrupole electromagnet, and flow to each quadrupole electromagnet A quadrupole electromagnet current control device that can individually change the current value, a beam position monitor that detects the position of the electron beam, and each quadrupole electromagnetic Trajectory correction device of the electron beam, characterized in that an arithmetic unit for calculating an exciting current of each steering electromagnet. Therefore deflection angle that passes through the center of.
  However, the process of calculating the excitation current of each steering electromagnet for the deflection angle such that the electron beam passes through the center of each quadrupole electromagnet by the arithmetic unit is as follows.
  First, the displacement of the electron beam in the beam position monitor when the exciting current amounts of the first and second quadrupole electromagnets are individually changed by a predetermined amount without exciting all the steering electromagnets, respectively. Detected, and secondly, when the excitation current amount of the first and second quadrupole electromagnets is individually changed by a predetermined amount while the excitation current is supplied to the first steering electromagnet alone. The displacement of the electron beam is detected in the beam position monitor, and thirdly, the excitation current amount of the first and second quadrupole electromagnets is determined in a state where a predetermined amount of excitation current is supplied to the second steering electromagnet alone. The displacement of the electron beam in the beam position monitor when each is changed by a predetermined amount is detected, and fourthly, with respect to the first quadrupole electromagnet, the excitation current amount of the first quadrupole electromagnet is determined by a predetermined amount. change In this case, based on the condition that the position of the electron beam in the beam position monitor does not change, a first equation with the respective exciting current amounts of the first and second steering electromagnets as variables is created. In addition, for the second quadrupole electromagnet, the first quadrupole electromagnet is based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the second quadrupole electromagnet is changed by a predetermined amount. , A second equation having the respective exciting current amounts of the second steering electromagnets as variables is created, and sixth, the first and second steering electromagnets are defined as simultaneous equations. Exciting current amount solutioncalculate.
[0043]
If comprised in this way, the trajectory of an electron beam can be easily corrected so that the trajectory of an electron beam passes through the center of a quadrupole electromagnet, and it becomes possible to make a high-quality electron storage ring.
In addition, since the correction is performed by actually detecting the magnetic field center position of the quadrupole electromagnet using the electron beam, even if the magnetic field center position of the quadrupole electromagnet is shifted during the operation of the electron storage ring, The electron beam trajectory can be easily corrected. Furthermore, since the trajectory of the electron beam can be corrected so as to pass through the center of the magnetic field of the quadrupole electromagnet, the calibration error and installation error of the beam position monitor do not affect the trajectory correction.
[0044]
In the electron beam trajectory correction method according to claim 2, in the electron storage ring including the electron beam trajectory correction device according to claim 1, first, all the steering electromagnets are not excited. 1. Detecting the displacement of the electron beam in the beam position monitor when the excitation current of the second quadrupole electromagnet is changed by a predetermined amount, respectively. Second, exciting the first steering electromagnet independently. The displacement of the electron beam in the beam position monitor when the excitation current amounts of the first and second quadrupole electromagnets are each independently changed by a predetermined amount with a predetermined amount of current supplied is detected. The beam position monitor when the excitation current amounts of the first and second quadrupole electromagnets are individually changed by a predetermined amount while a predetermined amount of excitation current is supplied to the second steering electromagnet alone. The fourth position of the electron beam in the beam position monitor is detected even if the amount of excitation current of the first quadrupole electromagnet is changed by a predetermined amount for the first quadrupole electromagnet. Based on the condition that does not change, a first equation with the respective excitation current amounts of the first and second steering electromagnets as variables is created. Fifth, for the second quadrupole electromagnet, The excitation current amounts of the first and second steering electromagnets are based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the quadrupole electromagnet 2 is changed by a predetermined amount. 6 is used to calculate a solution of the excitation current amounts of the first and second steering electromagnets using the first and second equations as simultaneous equations, and seventh. , Calculated in the sixth Based on the exciting current amounts of the first and second steering electromagnets, the exciting current amounts of the first and second steering electromagnets are controlled so that the electron beam is centered on both the first and second quadrupole electromagnets. It was corrected to pass.
[0045]
Specifically, the electron beam trajectory correction method in the electron storage ring provided with the electron beam trajectory correction apparatus of the present invention may be performed according to such a procedure.
[0046]
  The electron beam trajectory correction apparatus according to claim 3 includes a plurality of deflection electromagnets and first to n-th n quadrupole electromagnets, and an electron beam (including positrons) is desired in a closed trajectory. 1 to m-th steering electromagnets for deflecting an electron beam vertically and horizontally, and a steering electromagnet for supplying an excitation current to each of the steering electromagnets Power supply, a steering current control device for controlling the excitation current of each steering electromagnet, a quadrupole electromagnet power supply for excitation of each quadrupole electromagnet, and a current value flowing to each quadrupole electromagnet, respectively A quadrupole electromagnet current control device that can be changed individually, a beam position monitor that detects the position of the electron beam, and an electron beam that passes through the center of each quadrupole electromagnet. Trajectory correction device of the electron beam, characterized in that an arithmetic unit for calculating an exciting current of each steering magnets for the deflection angle like.
  However, n and m are both natural numbers and n ≧ m.
  Further, the process of calculating the excitation current of each steering electromagnet for the deflection angle so that the electron beam passes through the center of each quadrupole electromagnet by the arithmetic unit is as follows.
  First, the displacement of the electron beam in the beam position monitor is detected when the excitation current amount of the p-th quadrupole electromagnet is changed by a predetermined amount without exciting all the steering electromagnets. The displacement of the electron beam in the beam position monitor when the excitation current amount of the pth quadrupole electromagnet alone is changed by a predetermined amount while the predetermined amount of excitation current is supplied to the qth steering electromagnet alone. Third, based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the p-th quadrupole electromagnet is changed by a predetermined amount for the p-th quadrupole electromagnet. Then, a p-th equation with the respective exciting current amounts of the q-th steering electromagnets as variables is created. Fourth, the n equations created in the third are used as simultaneous equations, and fifth, = For m, calculated by solving the simultaneous equations, whereas, in the case of n> m, is calculated by solving the simultaneous equations to the optimum value by the least square method.
  However, p and q are integers of 1 ≦ p ≦ n and 1 ≦ q ≦ m, p is assumed to sequentially vary from 1 to n, and q is sequentially varied from 1 to m.
[0047]
With such a configuration, it is possible to cope with the case where the number of steering electromagnets is generalized to m and the number of quadrupole electromagnets is generalized to n.
[0048]
  According to a fourth aspect of the present invention, there is provided an electron beam trajectory correction method comprising: an electron storage ring including the electron beam trajectory correction device according to claim 3; The displacement of the electron beam in the beam position monitor is detected when the amount of excitation current of the p quadrupole electromagnet alone is changed by a predetermined amount, and secondly, a predetermined amount of excitation current is supplied independently to the q-th steering electromagnet. In this state, the displacement of the electron beam in the beam position monitor when the excitation current amount of the p-th quadrupole electromagnet is changed by a predetermined amount alone is detected. Third, about the p-th quadrupole electromagnet, The qth steering electromagnet is based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the pth quadrupole electromagnet is changed by a predetermined amount. Create an equation of the p to the exciting current of each variable, the fourth, and the simultaneous equations of n equations created above thirdFifth, when n = m, the exciting current amounts of the first to m-th steering electromagnets are calculated based on the exciting current amounts of the first to m-th steering electromagnets calculated by solving the simultaneous equations. On the other hand, in the case of n> m, the first to the first through the first to the m-th steering electromagnets calculated by optimizing the simultaneous equations by the least square method and solving them are used. m to control the amount of exciting current of the steering electromagnet,An electron beam trajectory correction method, wherein the electron beam is corrected so as to pass through the center of each of the first to nth quadrupole electromagnets.
  However, p and q are integers of 1 ≦ p ≦ n and 1 ≦ q ≦ m, p is assumed to sequentially vary from 1 to n, and q is sequentially varied from 1 to m.
[0049]
Even when the number of steering electromagnets and quadrupole electromagnets is generalized to m and n, respectively, specifically, the trajectory of the electron beam may be corrected by such a procedure.
[0050]
  Claim 5Or 6In the electron beam trajectory correction method or the electron beam trajectory correction method described in 1), a plurality of the beam position monitors are provided, and the beam position monitors are arranged at appropriate positions of the electron storage ring.
  In this way, the trajectory correction of the electron beam can be performed more precisely, and it becomes possible to cope with an electron storage ring that requires ultra-high precision.
[0051]
DETAILED DESCRIPTION OF THE INVENTION
The electron beam trajectory correction apparatus of the present invention (hereinafter sometimes referred to as “correction device” for simplicity) and the electron beam trajectory correction method (hereinafter also referred to as “correction method”). )) About the first embodiment and the second embodiment,
This will be described with reference to FIGS.
[0052]
In the following, in order to facilitate the understanding of the present invention, first, as a first embodiment of the correction device of the present invention, an example of an electron storage ring using two quadrupole electromagnets and two steering electromagnets. Will be described with reference to FIGS. 1 to 3.
Next, based on the description of the first embodiment, as a second embodiment of the correction apparatus of the present invention, a generalized case using n quadrupole electromagnets and m steering electromagnets is used. An electron beam trajectory correction apparatus in the electron storage ring will be described with reference to FIG.
[0053]
First embodiment:
First, a first embodiment of an electron beam trajectory correcting apparatus according to the present invention will be described with reference to FIGS.
FIG. 1 is a block diagram showing the configuration of an electron beam trajectory correction apparatus according to the present invention.
FIG. 2 is a plan view of the electron storage ring showing the installation location of the steering electromagnet and beam position monitor used in the correction apparatus of the present invention.
FIG. 3 is a flowchart for explaining an electron beam trajectory correction method using the electron beam trajectory correction apparatus of the present invention.
[0054]
As shown in FIG. 1, the electron beam trajectory correcting apparatus 10A of the present invention mainly has a configuration of a steering system related to the steering electromagnets 60A and 60B and a configuration of a quadrupole electromagnet system related to the quadrupole electromagnets 70A and 70B. Divided.
In the following, these two systems will be broadly described.
[0055]
First, in the steering system, as described above, the first and second steering electromagnets 60A and 60B that deflect the electron beam in the vertical and horizontal directions by the action of the magnetic field, and the exciting current are supplied to the steering electromagnets 60A and 60B. Steering electromagnet power supplies 62A and 62B, and steering current control devices 64A and 64B for controlling excitation currents supplied from the steering electromagnet power supplies 62A and 62B to the steering electromagnets 60A and 60B.
[0056]
As will be described later, the steering current control devices 64A and 64B control the excitation current amounts of the steering electromagnets 60A and 60B via the steering electromagnet power supplies 62A and 62B, and information about the current amounts is described later. 12 to send.
Further, the steering current control devices 64A and 64B control the excitation current amount of the steering electromagnets 60A and 60B with the optimum value of the excitation current amount calculated by the arithmetic device 12.
[0057]
Further, the quadrupole electromagnet system includes a quadrupole electromagnet excitation power source 72 and a shunt 74 as a quadrupole electromagnet current control device capable of individually changing the current from the excitation power source 72. ing.
As will be described later, the shunt 74 sends information about the amount of change when the amount of exciting current of the quadrupole electromagnets 70A and 70B is changed to the arithmetic unit 12 described later.
[0058]
As other components, as shown in FIG. 1, a beam position monitor 92 for detecting the position of the electron beam and an excitation current amount to be applied to the steering electromagnets 60A and 60B are calculated, and from a microcomputer or the like. And an arithmetic device 12 configured.
[0059]
FIG. 2 shows an arrangement of two quadrupole electromagnets 70A and 70B, a beam position monitor 92, and steering electromagnets 60A and 60B for supplementary explanation.
FIG. 2 shows a beam position monitor 92, steering electromagnets 60A and 60B, quadrupole electromagnets 70A and 70B, and deflecting electromagnets 90A and 90B, which are the main components of the correction apparatus 10A in the present embodiment. Other configurations of the electron storage ring 100 are omitted for convenience of explanation.
[0060]
As shown in FIG. 2, in the electron storage ring 100 to which the correction device 10A of the present embodiment is attached, quadrupole electromagnets 70A and 70B are respectively attached to the center positions of the two linear portions.
Steering electromagnets 60A and 60B, which are the main components of the correction device 10A, are attached to the upstream positions of the electron beams of the quadrupole electromagnets 70A and 70B, and the beam positions at appropriate positions convenient for monitoring the electron beams. A monitor 92 is arranged.
[0061]
With the above configuration, the basic operation and the trajectory correction method of the electron beam trajectory correction apparatus 10A according to the present embodiment will be described with reference to FIG.
Although the electron beam trajectory correction is performed both in the horizontal direction and in the vertical direction, the correction method in the horizontal direction and the vertical direction is almost the same procedure, and will be described below without particular distinction.
[0062]
First, in order to facilitate the understanding of the present invention, the basic concept of the present invention will be described.
The light that passes through the central axis of the convex lens does not deviate from the central axis even if the focal length varies due to a change in the focusing power of the convex lens. However, the light that is off the central axis and passes through the convex lens is displaced in the distance from the central axis when the focal length of the convex lens changes.
[0063]
Similarly, since the quadrupole electromagnet has the function of focusing the electron beam, if the amount of excitation current of the quadrupole electromagnet is changed to change the focusing force of the quadrupole electromagnet, the electron beam is As described above, there is a problem that the quality of the electron storage ring is deteriorated when the electron beam is displaced without passing through the center of the quadrupole electromagnet.
[0064]
Therefore, in the present invention, on the contrary, by utilizing this property, the excitation current amount of the quadrupole electromagnet is changed to intentionally displace the trajectory of the electron beam, and the misalignment of the electron beam from the center is obtained. The optimum value of the excitation current amount of the steering electromagnet is calculated, and the trajectory of the electron beam is corrected so that the electron beam passes through the magnetic field center of the quadrupole electromagnet.
This method will be described in detail below.
[0065]
First, as shown in FIG. 3, after the start of the electron beam trajectory correction (ST1), first, the first and second quadrupole electromagnets 70A in a state where all the steering electromagnets 60A and 60B are not excited. , 70B respectively detect the displacement of the electron beam in the beam position monitor 92 when the excitation current amount is changed by a predetermined amount IQ (1) and IQ (2), respectively, and this displacement is respectively detected by Z (1,0). ), Z (2, 0) (ST2).
[0066]
Here, as for the index in parentheses regarding Z, “1” on the left means the first quadrupole electromagnet 70A, and similarly, “2” on the left means the second quadrupole electromagnet 70B, and “ “0” indicates a state in which all the steering electromagnets 60A and 60B are not excited.
Further, as shown in FIG. 1, the change amounts IQ (1) and IQ (2) of the excitation current amounts of the first and second quadrupole electromagnets 70A and 70B and the displacement Z ( 1, 0) and Z (2, 0) are sent to the arithmetic unit 12 (the same applies hereinafter).
[0067]
Secondly, the excitation current amounts of the first and second quadrupole electromagnets 70A and 70B are individually set in a state where the excitation current is supplied to the first steering electromagnet 60A by a predetermined amount IS (1) alone. The displacement of the electron beam in the beam position monitor 92 when it is changed by a predetermined amount is detected respectively, and these displacements are set as Z (1,1) and Z (2,1), respectively (ST3).
[0068]
Here, as for the index in parentheses regarding Z, “1” on the right indicates a state where the first steering electromagnet 60A is individually excited.
Further, as shown in FIG. 1, the excitation current IS (1) of the first steering electromagnet 60A and the data of the electron beam displacements Z (1,1) and Z (2,1) in the beam position monitor 92 are calculated. It is sent to the device 12 (the same applies hereinafter).
[0069]
Third, similarly, the excitation current amounts of the first and second quadrupole electromagnets 70A and 70B are independently set in a state where the excitation current is supplied to the second steering electromagnet 60B by a predetermined amount IS (2). Then, the displacement of the electron beam in the beam position monitor 92 when the predetermined amount is changed is detected, and these displacements are set as Z (1,2) and Z (2,2), respectively (ST4).
Here, as for the index in parentheses regarding Z, “2” on the right indicates a state in which the second steering electromagnet 60B is excited individually.
[0070]
Fourth, regarding the first quadrupole electromagnet 60A, even if the excitation current amount of the first quadrupole electromagnet 60A is changed by a predetermined amount IQ (1), the position of the electron beam on the beam position monitor 92 changes. On the basis of the condition that the first and second steering electromagnets are not based on the condition, the first equation with the variables X (1) · IS (1), X (2) · IS (2) It is created in the arithmetic unit 12 (ST5).
[0071]
This first equation is given by:

[0072]
Note that the variable X (1) is a ratio of the second exciting current amount IS (1) flowing through the first steering electromagnet 60A, and the variable X (2) is The third represents a ratio with a predetermined excitation current IS (2) passed through the second steering electromagnet 60B (the same applies hereinafter).
In the equation (1), since the deflection angle by the steering electromagnets 60A and 60B is actually extremely small, it is assumed that the excitation current amount and the displacement accompanying it are in a proportional relationship (the same applies hereinafter).
[0073]
Fifth, for the second quadrupole electromagnet 60B, the electron beam position in the beam position monitor 92 does not change even if the excitation current amount of the second quadrupole electromagnet 60B is changed by a predetermined amount. Then, the second equation with the respective excitation current amounts of the first and second steering electromagnets as variables X (1) · IS (1), X (2) · IS (2) Create (ST6).
[0074]
This second equation is given by:

[0075]
Sixth, as shown in ST7 of FIG. 3, the solutions of X (1) and X (2) are obtained by using the first and second equations, the expressions (1) and (2) as simultaneous equations, The amount of exciting current of the first and second steering electromagnets 60A and 60B is calculated by the arithmetic unit 12.
[0076]
Seventh, based on the excitation current amounts of the first and second steering electromagnets calculated in the sixth, the excitation current amounts X (1) and IS (1) of the first and second steering electromagnets 60A and 60B, X (2) and IS (2) are controlled by the steering current control devices 64A and 64B (ST8).
[0077]
As described above, if the electron beam passes through the magnetic field centers of the quadrupole electromagnets 70A and 70B, the electron beam position monitor 92 will not be displaced even if the excitation current amount of the quadrupole electromagnets 70A and 70B is changed. Thus, by controlling the amount of excitation current of the steering electromagnets 60A and 60B, the electron beam can be corrected to pass through the center of both quadrupole electromagnets 70A and 70B. The electron beam trajectory correction method of the present invention is completed (ST9).
[0078]
In the above description, the displacement measurements shown in the first to third can be performed independently and do not necessarily have to be performed in this order. That is, these are given for convenience in order to explain the procedure of the correction method. For example, the displacement may be measured in the second, third, and first order.
[0079]
As described above, when the trajectory correction apparatus 10A of the present invention is used, the position of the electron beam can be easily corrected so that the trajectory of the electron beam passes through the center of the quadrupole electromagnet. It becomes possible.
[0080]
In addition, since the trajectory correction is performed with the electron beam actually accumulated, even if the magnetic field center position of the quadrupole electromagnet shifts during operation of the electron storage ring, the trajectory correction corresponding to it can be easily performed. Can do.
[0081]
Furthermore, since the trajectory of the electron beam can be corrected so as to pass through the center of the magnetic field of the quadrupole electromagnet, the calibration error and installation error of the beam position monitor do not affect the trajectory correction.
[0082]
Second embodiment:
In the first embodiment, in order to facilitate the understanding of the skeleton of the present invention, the case where the number of quadrupole electromagnets is two and the number of steering electromagnets is two has been described. In the second embodiment, the number of quadrupole electromagnets is n and the number of steering electromagnets is m, which is a generalized example. This second embodiment will be described with reference to FIG. Explain.
[0083]
FIG. 4 is a block diagram showing the configuration of the second embodiment of the electron beam trajectory correcting apparatus of the present invention.
The trajectory correction apparatus 10B in the present embodiment is not fundamentally different from the trajectory correction apparatus 10A shown in FIG. 1 in the main configuration, and generally includes n quadrupole electromagnets and m steering electromagnets. It corresponds to the case where it is extended.
[0084]
That is, as shown in FIG. 4, the electron beam trajectory correction apparatus 10B in the present embodiment first supplies m exciting electromagnets 60A1 to 60Am and an excitation current to the steering electromagnets 60A1 to 60Am in the steering system. Steering electromagnet power supplies 62A1 to 62Am, and steering current control devices 64A1 to 64Am for controlling the excitation current supplied from the steering electromagnet power supplies 62A1 to 62Am to the steering electromagnets 60A1 to 60Am.
[0085]
The quadrupole electromagnet system related to the quadrupole electromagnets 70A1 to 70Am includes a quadrupole electromagnet power source 72 and a shunt 74 that can individually change the current from the power source 72. Yes.
As other components, as shown in FIG. 4, a beam position monitor 92 for detecting the position of the electron beam and an arithmetic unit 12 for calculating the amount of excitation current to be applied to the steering electromagnets 60A1 to 60Am are provided. I have.
[0086]
With the above configuration, the basic operation and the trajectory correction method of the electron beam trajectory correction apparatus 10B according to the present embodiment will be described with reference to FIG.
The basic operation of the trajectory correction apparatus 10B in the present embodiment is not fundamentally different from that of the first embodiment, and is generally expanded when n quadrupole electromagnets and m steering electromagnets are expanded. It corresponds.
[0087]
First, the displacement of the electron beam is detected in the beam position monitor when the excitation current amount of the p-th quadrupole electromagnet alone is changed by a predetermined amount without exciting all the steering electromagnets. Is Z (p, 0).
Here, of course, p is an integer of 1 ≦ p ≦ n.
By sequentially changing the integer p from 1 to n, the displacements of the first to nth quadrupole electromagnets 70A1 to 70An can be obtained as Z (1, 0) to Z (n, 0), respectively.
[0088]
Second, the electron in the beam position monitor when the excitation current amount of the p-th quadrupole electromagnet 70Ap is changed by a predetermined amount alone in a state where the predetermined amount of excitation current is supplied to the q-th steering electromagnet 60Aq alone. The displacement of the beam is detected, and this displacement is defined as Z (p, q).
Of course, q is an integer of 1 ≦ q ≦ m.
[0089]
Here, when the integer q is sequentially changed from 1 to m, the excitation current of the p-th quadrupole electromagnet 70Ap that has independently supplied a predetermined amount of excitation current to the q-th steering electromagnet 60Aq is changed to predetermined both sides. Can be obtained as Z (p, 1) to Z (p, m), respectively.
[0090]
The amount of change in the excitation current amount of each quadrupole electromagnet 70A1 to 70Am is the same amount of change for the same quadrupole electromagnet 70A1 to 70Am in the process of sequentially changing the integer q from 1 to m. Shall.
[0091]
Further, by repeating this procedure while sequentially changing the integer p from 1 to n, the displacements of the first to n-th quadrupole electromagnets 70A1 to 70Am are changed to Z (1,1) to Z (n, m) n displacements of m) can be calculated.
[0092]
Third, for the p-th quadrupole electromagnet, based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the p-th quadrupole electromagnet is changed by a predetermined amount, A p-th equation is created with the amount of exciting current of each of the q-th steering electromagnets as a variable.
By sequentially changing p from 1 to n, n equations can be created in the arithmetic unit 12.
[0093]
These n equations are given by the following equation.

[0094]
  Fourthly, the n equations created in the third are replaced with simultaneous equations.And in the following wayA solution of the excitation current amount of the first to m-th steering electromagnets is calculated.
[0095]
  By the way, in the case of n <m, the simultaneous equations cannot be solved, and therefore it is necessary that n = m or n> m.
Accordingly, fifthly, when n = m, the excitation of the first to mth steering electromagnets is based on the amount of excitation current of the first to mth steering electromagnets calculated by solving the fourth simultaneous equation. Control the amount of current.
[0096]
  On the other hand, if n> m, the fourth simultaneous equation isExcitation current amounts of the first to m-th steering electromagnets calculated by optimization using the least square methodBased on the above, the exciting current amount of the first to m-th steering electromagnets is controlled.
[0097]
Thus, when the trajectory correction apparatus 10B of the present invention is used, even when the number of quadrupole electromagnets is n and the number of steering electromagnets is generalized to m, the trajectory of the electron beam is easily centered on the magnetic field of the quadrupole electromagnet. The trajectory of the electron beam can be corrected so as to pass through the high-quality electron storage ring.
[0098]
Similarly, since the trajectory correction is performed with the electron beam actually accumulated, even if the magnetic field center position of the quadrupole electromagnet shifts during the operation of the electron storage ring, it can be easily dealt with. The trajectory can be corrected.
In the above description, the measurement of displacement shown in the first and second can be performed independently, and is not necessarily restricted in this order, as described in the first embodiment. I will note that.
[0099]
The electron beam trajectory correcting apparatus of the present invention is not limited to the above-described embodiments, and various modifications are possible.
For example, in each of the above-described embodiments, the case where only one beam position monitor is used has been described. You may comprise so that it may correct | amend.
[0100]
In this case, the above-described electron beam trajectory correction is performed in each beam position monitor. This makes it possible to perform electron beam trajectory correction with higher accuracy, and for example, ultra-high accuracy is required. It is possible to deal with an electron storage ring.
[0101]
【The invention's effect】
(1) Since the electron beam trajectory correction apparatus of the present invention is configured as described in claim 1, the electron beam trajectory can be easily corrected so as to pass through the center of the quadrupole electromagnet, As a result, a high-quality electron storage ring can be obtained.
(2) Since the correction is performed by actually detecting the magnetic field center position of the quadrupole electromagnet using the electron beam, the magnetic field center position of the quadrupole electromagnet may be shifted during operation of the electron storage ring. However, the corresponding position can be easily corrected.
(3) Furthermore, the electron beam trajectory can be corrected so that it passes through the center of the magnetic field of the quadrupole electromagnet without focusing on the center position of the beam position monitor. Does not affect.
[0102]
(4) Specifically, the trajectory correction method using the electron beam trajectory correction apparatus according to claim 1 may be performed according to the procedure as described in claim 2.
[0103]
(5) The electron beam trajectory correction apparatus according to the present invention is configured as described in claim 3 and can cope with the case where the number of steering electromagnets is m and the number of quadrupole electromagnets is n. Is possible.
[0104]
(6) Specifically, the trajectory correction method using the electron beam trajectory correction apparatus according to claim 3 may be performed according to the procedure as described in claim 4.
[0105]
(7) Further, claim 5Or 6If it is configured as described in (1), the trajectory correction of the electron beam can be performed more precisely, and it becomes possible to cope with an electron storage ring that requires ultra-high precision.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of an electron beam trajectory correcting apparatus of the present invention.
FIG. 2 is a plan view of an electron storage ring showing the arrangement of main components used in the first embodiment of the electron beam trajectory correction apparatus of the present invention.
FIG. 3 is a flowchart for explaining a basic operation of the first embodiment of the electron beam trajectory correcting apparatus of the present invention;
FIG. 4 is a block diagram showing a second embodiment of the electron beam trajectory correcting apparatus of the present invention.
FIG. 5 is a plan view for explaining a basic configuration of an electron storage ring.
FIG. 6 is a longitudinal sectional view showing a configuration of a beam position monitor used for an electron storage ring.
FIG. 7 is a longitudinal sectional view showing a configuration of a steering electromagnet.
FIG. 8 is a side view showing a configuration of a steering electromagnet.
[Explanation of symbols]
10A, 10B: Orbit correction device for electron beam
12: Arithmetic unit
60: Steering electromagnet
62: Power source for steering electromagnet
64: Steering current control device
70: Quadrupole electromagnet
72: Power supply for quadrupole electromagnet
74: Shunt
90A, 90B: Bending electromagnet
92: Beam position monitor
100: Electron storage ring

Claims (6)

In an electron storage ring comprising a plurality of deflecting electromagnets and first and second quadrupole electromagnets, and storing an electron (including positron) beam in a closed orbit with a desired energy,
First and second steering electromagnets for deflecting the electron beam vertically and horizontally;
A steering electromagnet power supply for supplying an excitation current to each steering electromagnet;
A steering current control device for controlling the excitation current of each steering electromagnet;
A quadrupole electromagnet power source for exciting each quadrupole electromagnet;
A quadrupole electromagnet current control device capable of individually changing the current value flowing to each quadrupole electromagnet;
A beam position monitor that detects the position of the electron beam;
An electron beam trajectory correction apparatus comprising: an arithmetic unit that calculates an excitation current of each steering electromagnet so that the electron beam has a deflection angle that passes through the center of each quadrupole electromagnet.
However, the process of calculating the excitation current of each steering electromagnet for the deflection angle such that the electron beam passes through the center of each quadrupole electromagnet by the arithmetic unit is as follows.
First, the displacement of the electron beam in the beam position monitor when the exciting current amounts of the first and second quadrupole electromagnets are individually changed by a predetermined amount without exciting all the steering electromagnets, respectively. Detect
Second, a beam position monitor when the excitation current amount of the first and second quadrupole electromagnets is changed by a predetermined amount independently while a predetermined amount of excitation current is supplied to the first steering electromagnet alone. Detecting the displacement of the electron beam in each
Third, the beam position monitor when the excitation current amount of the first and second quadrupole electromagnets is individually changed by a predetermined amount while the predetermined amount of excitation current is supplied to the second steering electromagnet alone. Detecting the displacement of the electron beam in each
Fourth, for the first quadrupole electromagnet, based on the condition that even if the excitation current amount of the first quadrupole electromagnet is changed by a predetermined amount, the position of the electron beam in the beam position monitor does not change, Create a first equation with the exciting current amounts of the first and second steering electromagnets as variables,
Fifth, for the second quadrupole electromagnet, based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the second quadrupole electromagnet is changed by a predetermined amount, Create a second equation with the respective excitation current amounts of the first and second steering electromagnets as variables,
Sixth, using the first and second equations as simultaneous equations, the solution of the excitation current amounts of the first and second steering electromagnets is calculated. An electron storage ring comprising the electron beam trajectory correction device according to claim 1.
First, the displacement of the electron beam in the beam position monitor when the exciting current amounts of the first and second quadrupole electromagnets are individually changed by a predetermined amount without exciting all the steering electromagnets, respectively. Detect
Second, a beam position monitor when the excitation current amount of the first and second quadrupole electromagnets is changed by a predetermined amount independently while a predetermined amount of excitation current is supplied to the first steering electromagnet alone. Detecting the displacement of the electron beam in each
Third, the beam position monitor when the excitation current amount of the first and second quadrupole electromagnets is individually changed by a predetermined amount while the predetermined amount of excitation current is supplied to the second steering electromagnet alone. Detecting the displacement of the electron beam in each
Fourth, for the first quadrupole electromagnet, based on the condition that even if the excitation current amount of the first quadrupole electromagnet is changed by a predetermined amount, the position of the electron beam in the beam position monitor does not change, Create a first equation with the exciting current amounts of the first and second steering electromagnets as variables,
Fifth, for the second quadrupole electromagnet, based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the second quadrupole electromagnet is changed by a predetermined amount, Create a second equation with the respective excitation current amounts of the first and second steering electromagnets as variables,
Sixth, using the first and second equations as simultaneous equations, the solution of the excitation current amount of the first and second steering electromagnets is calculated,
Seventh, based on the excitation current amounts of the first and second steering electromagnets calculated in the sixth, the excitation current amounts of the first and second steering electromagnets are controlled,
An electron beam trajectory correction method, wherein the electron beam is corrected so as to pass through the centers of both the first and second quadrupole magnets. In an electron storage ring comprising a plurality of deflection electromagnets and first to n-th n quadrupole electromagnets, and configured to store an electron (including positron) beam in a closed orbit with a desired energy,
First to m-th m steering electromagnets for deflecting the electron beam vertically and horizontally;
A steering electromagnet power supply for supplying an excitation current to each steering electromagnet;
A steering current control device for controlling the excitation current of each steering electromagnet;
A quadrupole electromagnet power source for exciting each quadrupole electromagnet;
A quadrupole electromagnet current control device capable of individually changing the current value flowing to each quadrupole electromagnet;
A beam position monitor that detects the position of the electron beam;
An electron beam trajectory correction apparatus comprising: an arithmetic unit that calculates an excitation current of each steering electromagnet so that the electron beam has a deflection angle that passes through the center of each quadrupole electromagnet.
However, n and m are both natural numbers and n ≧ m.
Further, the process of calculating the excitation current of each steering electromagnet for the deflection angle so that the electron beam passes through the center of each quadrupole electromagnet by the arithmetic unit is as follows.
First, the displacement of the electron beam in the beam position monitor when the excitation current amount of the pth quadrupole electromagnet is changed by a predetermined amount alone without exciting all the steering electromagnets,
Second, the electron beam current in the beam position monitor when the excitation current amount of the pth quadrupole electromagnet alone is changed by a predetermined amount while the predetermined amount of excitation current is supplied to the qth steering electromagnet alone. Detect displacement,
Third, for the p-th quadrupole electromagnet, based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the p-th quadrupole electromagnet is changed by a predetermined amount, Create a p-th equation with the amount of exciting current of each of the q-th steering electromagnets as a variable,
Fourth, the n equations created in the above third are simultaneous equations,
Fifth, when n = m, the calculation is performed by solving the simultaneous equations. On the other hand, when n> m, the calculation is performed by optimizing and solving the simultaneous equations by the method of least squares.
However, p and q are integers of 1 ≦ p ≦ n and 1 ≦ q ≦ m, p is assumed to sequentially vary from 1 to n, and q is sequentially varied from 1 to m. An electron storage ring comprising the electron beam trajectory correction device according to claim 3.
First, the displacement of the electron beam in the beam position monitor when the excitation current amount of the pth quadrupole electromagnet is changed by a predetermined amount alone without exciting all the steering electromagnets,
Second, the electron beam current in the beam position monitor when the excitation current amount of the pth quadrupole electromagnet alone is changed by a predetermined amount while the predetermined amount of excitation current is supplied to the qth steering electromagnet alone. Detect displacement,
Third, for the p-th quadrupole electromagnet, based on the condition that the position of the electron beam in the beam position monitor does not change even if the excitation current amount of the p-th quadrupole electromagnet is changed by a predetermined amount, Create a p-th equation with the amount of exciting current of each of the q-th steering electromagnets as a variable,
Fourth, the n equations created in the above third are simultaneous equations ,
Fifth, when n = m, the excitation current amounts of the first to m-th steering electromagnets are controlled based on the excitation current amounts of the first to m-th steering electromagnets calculated by solving the simultaneous equations. On the other hand, if n> m, the first to mth mth steering currents are calculated based on the excitation current amounts of the first to mth steering electromagnets calculated by optimizing and solving the simultaneous equations by the least square method. Control the amount of exciting current of the steering electromagnet,
An electron beam trajectory correction method, wherein the electron beam is corrected so as to pass through the center of each of the first to nth quadrupole electromagnets.
However, p and q are integers of 1 ≦ p ≦ n and 1 ≦ q ≦ m, p is assumed to sequentially vary from 1 to n, and q is sequentially varied from 1 to m.   4. The electron beam trajectory correcting apparatus according to claim 1, wherein a plurality of the beam position monitors are provided, and the beam position monitors are arranged at appropriate positions of the electron storage ring.   5. The electron beam trajectory correction method according to claim 2, wherein a plurality of the beam position monitors are provided, and the beam position monitors are arranged at appropriate positions of the electron storage ring.

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