JP2001052899A - Orbiting frequency control device for electron in electron storage ring and electron trajectory correcting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an orbiting frequency control device for electrons in an electron storage ring and an electron trajectory correcting method, for stabilizing the orbiting trajectory of an electron beam without using any tuner. SOLUTION: This orbiting frequency control device 10 is equipped with a wiggler 90 inserted into an electron storage ring, a power supply 92 for excitation for exciting the wiggler 90, and an exciting-current control device 94 for controlling the amount of exciting current supplied from the power supply 92 for excitation to the wiggler 90, and adjusts the orbiting frequency of electrons orbiting within the electron storage ring by adjusting an electron trajectory within the wiggler 90 by controlling the amount of exciting current for the wiggler 90. The performance of the electron orbiting frequency control device 10 can be much enhanced by providing a central control device 20 equipped with a computing device 20a for computing the amount of exciting current for electron trajectory monitors 30A, 30B and for the wiggler 90, and a current-value setting signal generating device 20b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for accumulating an electron beam in a circular orbit at a desired energy, generating mainly synchrotron radiation, and using an insertion type light source to make high use of the radiation. More particularly, the present invention relates to an electron circulating frequency control device and an electron trajectory correction method for an electron storage ring that adjusts the circulating frequency of a stored electron beam.

[0002]

2. Description of the Related Art When charged particles such as electrons or positrons (hereinafter, collectively referred to as "electrons") and ions travel in a uniform magnetic field, a circular orbit (generally, 3 electrons) is generated by the action of Lorentz force perpendicular to the traveling direction. Dimensionally draw a spiral orbit).

Accordingly, using a bending electromagnet that generates a uniform magnetic field in the vertical direction, a charged particle having a constant kinetic energy is caused to draw an arc trajectory having a desired radius of curvature, and the traveling direction is bent at a desired angle. In addition, by arranging a plurality of bending electromagnets at appropriate positions, the charged particles can be made to orbit on an orbit in a horizontal plane.

[0004] That is, if the inside of the beam duct for accumulating the beam is kept in a vacuum, in principle, electrons can be accumulated in the orbit with desired energy only by the bending electromagnet.
In actual use, the electron storage ring requires a plurality of other devices. Therefore, the main configuration of the electron storage ring will be briefly described with reference to FIG.

FIG. 6 is a plan view of a race track 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. 6, 180 ° deflection type bending electromagnets 110A, 110B
Are arranged opposite to each other, and the orbit in the race-track-type beam duct 120 maintained at a high vacuum (up to 1 × 10 ⁻⁹ Torr) by a vacuum pump (not shown) (“designed orbit” or “closed orbit” for convenience of explanation) The electron beam is stored in BL.

According to the theory of relativity, when the kinetic energy of a particle increases, the mass increases with the kinetic energy, so that a phenomenon is seen in which the stored electrons are hardly bent in a magnetic field. Therefore, in order to confine the electron beam in a fixed design trajectory BL, generally, not only the one shown in FIG. 6 but also the electron storage ring adjusts the magnetic field strength of the bending electromagnet in conjunction with the energy of the electron beam.

Accordingly, the bending electromagnets 110A shown in FIG.
By reducing the field strength of 110B, any low energy electrons could theoretically be stored. However, when the electron energy is extremely small, there is a problem that the beam orbit becomes unstable and the electron beam cannot be stably stored for a long time.

Therefore, although not shown, electrons are accelerated to a constant energy by an injector so as to be incident on the electron storage ring 100. For example, in the type shown in FIG. 6, a pulse beam of electrons is accelerated to 150 MeV by an injector called a microtron. On the other hand, since the electrons made incident from the injector have a certain angle with respect to the orbit BL of the electron storage ring 100, the electrons of the electron beam A septum electromagnet (not shown) for changing the direction is used, and the septum electromagnet is incident on the electron storage ring 100 via the septum electromagnet.

In FIG. 6, reference numeral 130 denotes a quadrupole electromagnet. This quadrupole electromagnet 130 is rotationally symmetric
It has two magnetic poles, sets the magnetic field strength at the center to zero, forms a quadrupole magnetic field that has a magnetic field distribution that increases in proportion to the distance from the center, and the optical focusing lens collects light. Similarly, it plays a role of focusing the electron beam in the radial direction.

By these quadrupole electromagnets 130, the electron beam is stored in the electron storage ring 100 with stable and excellent beam quality without diverging from the orbit BL maintained in a high vacuum in the beam duct 120. Will be done. Although the electron storage ring 100 shown in FIG. 6 has eight quadrupole electromagnets 130 arranged therein, a straight line portion is shortened for compactness, and only two quadrupole electromagnets are arranged. Electron storage rings have also been put to practical use.

On the other hand, charged particles such as electrons have the property of emitting electromagnetic waves when subjected to an acceleration action. Therefore, the electron deflection electromagnets 110A, bendable when tangential to synchrotron radiation at 110B (S ynchrot
ron R diation: Hereinafter, it may be simply referred to as “SR” or “SR light” to emphasize that it is a kind of light. ), And the energy is attenuated.

Therefore, unless this energy loss is constantly compensated, there is a problem that the electron beam cannot be stably stored in the orbit BL with desired energy. In some cases, it is necessary to increase the energy of the stored electron beam to store electrons at a higher energy and to cope with various uses.

As described above, energy is supplied to the stored electron beam by the high-frequency accelerating cavity 140 shown in FIG.
It is. In brief, the high-frequency accelerating cavity 140 is a device to which high-frequency power is applied and electrons are emitted.
A device that synchronizes the phase of the high-frequency voltage generated in the high-frequency accelerating cavity 140 and the position of the electrons so as to be just accelerated when the acceleration gap approaches, and supplies energy to the stored electrons. is there.

The number of times the high-frequency voltage supplied to the high-frequency accelerating cavity 140 vibrates while the electrons make one round of the orbit BL in the electron storage ring 100 is referred to as a harmonic number.

By adjusting the length of the orbit BL and the frequency of the high frequency applied to the high frequency accelerating cavity 140 so that the harmonic number becomes an integer, energy is supplied each time an electron passes through the high frequency accelerating cavity 140. Can be devised so that it can be done. This makes it possible to supplement the energy loss of the electrons or to accelerate the electrons to a desired energy after the electrons are incident.

A method of accumulating the electron beam by the electron storage ring 100 shown in FIG. The electron beam accelerated to the desired energy by the injector is smoothly incident on the orbit BL of the electron storage ring 100 by the septum electromagnet.

Thereafter, in order to prevent a situation in which electrons collide with the septum electromagnet immediately after the incidence and disappear, a perturbation orbit deformed only at the time of incidence, called an incidence orbit, is formed by a part beta electromagnet (not shown). I do. After the energy dispersion of the electron group is attenuated, the electrons are stably accumulated with excellent beam quality in the orbit BL designed by the bending electromagnets 110A and 110B and the quadrupole electromagnet 130. Further, the high-frequency accelerating cavity 140 accumulates energy at a constant energy while supplementing the energy loss of the accumulated electron beam, or accelerates and accumulates at a desired energy.

By the way, as described above, in the electron storage ring, electrons are emitted from the bending electromagnet by emitting synchrotron radiation (SR) and energy is lost. This causes the upper limit of the energy of the electron beam that can be stored. It was one of the causes to define. In order to reduce the energy loss due to the SR and increase the energy of the electron beam that can be stored, a large electron storage ring has been developed by increasing the radius of curvature of the bending electromagnet.

On the other hand, SR is white light having a continuous spectrum with extremely high brightness and high directivity emitted in a certain horizontal plane. An electron storage ring has been developed to actively use this SR as a light source. ing. The electron storage ring 100 shown in FIG. 6 is a typical electron storage ring mainly developed as a light source for SR.

The electron storage ring 100 has a large current of the electron beam to be stored, reduces the radius of curvature of the bending electromagnet in a strong magnetic field, shortens the critical wavelength of SR to the X-ray region, and is particularly suitable for X-ray lithography. It is intended to be used as a small light source.

Next, a supplementary explanation of the insertion type light source inserted into the electron storage ring will be given. An insertion-type light source is inserted into the linear part of the electron storage ring and makes use of the property of emitting electrons by deflection to make the electrons meander or draw a spiral orbit by the action of a magnetic field. This is an apparatus for generating light having higher brightness than the bending electromagnets 110A and 110B and having specific properties such as circularly polarized light.

In FIG. 6, reference numeral 90 denotes one type of this insertion type light source called a wiggler. Reference numeral 92 denotes a power supply for the wiggler 90. As described above, the SR radiation spectrum generated at the bending electromagnets 110A and 110B of the electron storage ring 100 is white light continuous from far infrared rays to a relatively hard X-ray region, and the integrated radiation power is extremely high. However, this bending electromagnet 110A,
When the SR generated in the portion 110B is to be used by dispersing a narrow wavelength range, the light source is not necessarily a high-luminance light source.

Therefore, in the electron storage ring 100 of the type shown in FIGS. 6 and 7, the wiggler 90 is inserted into a straight line portion to forcibly meander the electron beam to radiate a SR of higher brightness and higher energy. The SR has been devised so that it can be used for various purposes.

The wiggler 90 will be described with reference to FIG. FIG. 7 is an essential part perspective view showing the deflecting magnets 90a to 90c of the wiggler 90 in order to explain the principle of vibrating the electron beam largely by the wiggler 90.

The wiggler 90 shown in FIG. 7 is called a three-pole wiggler in which three deflecting magnets 90a to 90c are alternately arranged with inverted polarities, and has the simplest configuration as an insertion type light source. is there. As described above, when the electrons travel in the magnetic field, they are deflected by the action of the Lorentz force. When the wiggler 90 is inserted into the linear portion of the electron storage ring 100, the stored electrons become as shown in FIGS. As shown, it vibrates roughly once. A more detailed description of the electron trajectory BL in the wiggler 90 will be described later.

The deflection magnet 90a of the three-pole wiggler 90
To 90c are deflecting magnets 9 having opposite polarities in order to restore the orbit largely bent by the central deflecting magnet 90b.
0a and 90c are arranged before and after, so that the integrated value of the magnetic field on the axis of the wiggler 90 is zero and the magnetic field distribution is designed to be symmetrical in the front and rear.

As a result, as shown in the plan view of FIG. 6, the electrons that have entered the wiggler 90 from the design trajectory BL vibrate once, and then return to the design trajectory BL even after exiting the wiggler 90. Is set.

By doing so, the electrons become wiggler 9
It is deflected in a magnetic field of 0, and forcibly emits SR light in a tangential direction. The type shown in FIGS. 6 and 7 is a superconducting electromagnet that cools an exciting coil at a liquid helium temperature in order to utilize the property that the wavelength of SR light emitted by electrons increases when the magnetic field intensity increases. Is used.

Thus, when a strong magnetic field is generated by the wiggler 90, white light having a spectrum shifted to a higher energy side than SR generated at the bending electromagnets 110A and 110B of the electron storage ring 100 can be obtained. Will be possible. Therefore, by using such a wiggler 90, it is possible to expand the usage of SR.

The wiggler 90 shown in FIGS.
Is a three-pole wiggler having three magnetic poles and vibrating the electron beam only once, as described above. But,
The wiggler includes a multipole wiggler of a type in which electrons are meandered more than once by increasing the number of magnetic poles. With this multipole wiggler, SR is superimposed in the traveling direction of electrons,
Strength can be increased.

6 and 7 are of the type using a superconducting electromagnet to generate a strong magnetic field, as described above. Some use conduction electromagnets or permanent magnets. Further, an electron storage ring using an insertion type light source, which is usually called an undulator, in which the number of magnetic poles is large and the electron beam meanders many times, has been put to practical use.

Next, the configuration of the high-frequency acceleration cavity 140 and the control device 150 of the high-frequency acceleration cavity for controlling the frequency of the high frequency supplied to the high-frequency acceleration cavity will be described with reference to FIGS.

First, the configuration of the control device 150 for the high-frequency acceleration cavity will be briefly described with reference to FIG. FIG.
FIG. 7 is a block diagram illustrating a schematic configuration of a control device 150 for the high-frequency acceleration cavity 140 that controls the frequency, supply power, and the like of the high-frequency acceleration cavity 140 used in the electron storage ring 100 of FIG. 6.

As shown in FIG. 8, the control device 150 for the high-frequency accelerating cavity includes a high-frequency oscillator 152 for generating a high frequency of a desired frequency, and a high-frequency oscillator for controlling the intensity and phase of the high-frequency signal of the high-frequency oscillator 152. The configuration includes a control circuit 154, a high-frequency amplifier 156 for amplifying high-frequency power from the high-frequency oscillator 152, a circulator 158 for protecting the high-frequency amplifier 156, and a directional coupler 159.

The directional coupler 159 is a high-frequency accelerating cavity 1
There is an apparatus for monitoring the power supplied to the power 40 and the power reflected by the high-frequency acceleration cavity 140.
If this is used, the high frequency acceleration cavity 1
It is possible to measure the degree of synchronization between the high frequency power 40 and the high frequency power supplied to the high frequency acceleration cavity 140.

Next, the structure of the high-frequency accelerating cavity 140 will be described with reference to FIGS. FIG. 9 shows a high-frequency accelerating cavity 140 formed in a beam duct 1 for accumulating an electron beam.
FIG. 4 is a longitudinal sectional side view showing a state where it is attached to the apparatus. Also,
FIG. 10 is an enlarged vertical sectional side view of a portion indicated by A in FIG.

The high-frequency accelerating cavity 140 is controlled by the high-frequency oscillator 152 so that the frequency of the high-frequency power becomes an integral multiple of the circulating frequency of the electrons circulating in the electron storage ring 100, so that the high-frequency phase and the high-frequency power are controlled. As described above, the device supplies energy to the electrons by well tuning the position of the electron.

As shown in FIG. 9, the high-frequency accelerating cavity 140 has a coupler 144 to which the amplified high-frequency is supplied.
, A tuner 146 for adjusting the resonance frequency of the high-frequency acceleration cavity 140, a cavity body 142, and, as shown in the enlarged view of FIG. 10, the tuner 146 and the high-frequency acceleration cavity 140.
And a contact finger 148 attached to the side wall of the cavity body 142 of the high-frequency accelerating cavity 140 in order to electrically connect the side wall of the high frequency accelerating cavity 140.

In FIG. 9, reference numeral 141 denotes a tuner port provided on the side wall of the high-frequency acceleration cavity 140;
5 is a coupler port, BL is a circular orbit of the electron beam passing through the high-frequency accelerating cavity 140, and the electron beam is in the beam duct 120 and a high-frequency accelerating cavity 14 maintained in a high vacuum.
It progresses in the direction of the arrow in 0.

The size and structure of the high-frequency accelerating cavity 140 are determined so as to resonate with the circulation of electrons at a predetermined frequency. The resonance frequency changes subtly.

As a countermeasure, the tuner 146 is connected to the high-frequency accelerating cavity 14 through the contact finger 148.
In the state of being electrically in contact with the side wall of No. 0, it is moved vertically by a remote control (the moving distance is about 2 cm), and the resonance frequency of the high-frequency acceleration cavity 140 is adjusted.

The tuner 146 is a high-frequency accelerating cavity 14.
In this configuration, a tuner port 141, which is a through hole, is formed in the side wall of the cavity body 142 of No. 0, and a conductor block is inserted therein. By changing the insertion amount, the inductance of the high-frequency acceleration cavity 140 is changed. And
By changing the inductance of the high-frequency acceleration cavity 140, the frequency of the high-frequency acceleration cavity 140 is adjusted so as to resonate with the circulation frequency of the electrons.

[0043]

In the above-described method of adjusting the frequency of the high-frequency accelerating cavity by using the conventional control device for the high-frequency accelerating cavity, the tuner attached to the high-frequency accelerating cavity is connected via the contact finger. As a result, mechanical operation is performed while making electrical contact with the side wall of the high-frequency accelerating cavity, causing the following problems.

First, since the tuner is slid while making electrical contact with the contact fingers attached to the side walls of the high-frequency acceleration cavity, the tuner and peripheral devices are liable to be mechanically damaged. Specifically, the nail of the contact finger is broken, a gap occurs with the tuner, a discharge occurs, a high-frequency power leaks out of the cavity,
The tuner is scraped off by the contact finger, or the contact finger bites into the tuner and the tuner does not move.

When the vacuum in the beam duct deteriorates, the amount of ions generated in the beam duct increases, and the beam diameter of the electron beam expands, thereby deteriorating the beam quality or losing the beam. I will. Therefore, it is necessary to maintain a high vacuum in the high-frequency accelerating cavity, and it is necessary to devise a method for preventing a leak from occurring at the tuner mounting portion. However, the tuner is provided with a drive mechanism for adjusting the insertion amount. Therefore, a complicated structure is required to maintain a high vacuum.

On the other hand, there is a method of synchronizing the high-frequency power and the high-frequency acceleration cavity without operating the tuner of the high-frequency acceleration cavity. This is a method in which the high-frequency oscillator 152 shown in FIG. 8 has a variable frequency function and changes the frequency of the high-frequency power.
This has the advantages that the configuration is simple and that no tuner needs to be attached to the high-frequency acceleration cavity.

However, when the frequency of the high-frequency power supplied to the high-frequency accelerating cavity is changed, the orbital frequency of the electron beam becomes
It changes in conjunction with this high frequency so as to be a fraction of an integer. This causes the following problems.

By the way, the orbital frequency of an electron is calculated by dividing the velocity of the electron by the orbital closed orbit length. Meanwhile, according to the theory of relativity can not any object than the light velocity C ₀ in a vacuum.

An electron storage ring 100 of the type shown in FIG.
Is designed to make electrons incident at an energy of 150 MeV and accelerate up to an energy of 700 MeV at the maximum. In such a high energy region (electron rest mass is 0.511 MeV), no problem as a traveling speed of the electron is constant light speed C _0.

Therefore, a change in the orbital frequency of an electron means a change in the closed orbital length of the electron, and a change in the closed orbital length of the electron means that the electron deviates from the design orbital. It means to go around. At this time, in an extreme case, the electron beam collides with the beam duct and disappears. Also, like a synchrotron radiation generator,
It can be said that a control method in which the orbit of the electron beam deviates from the design trajectory is inappropriate for a device that requires high stability with respect to the beam trajectory.

An object of the present invention is to solve the above-mentioned problems and to provide an electron orbit frequency control device and an electron orbit correction method in an electron storage ring for stabilizing an orbit of an electron beam without using a tuner. .

[0052]

According to a first aspect of the present invention, there is provided an electron circulating frequency control device for an electron storage ring, comprising: a plurality of bending electromagnets for deflecting an electron trajectory at a desired deflection angle; A high-frequency accelerating cavity for supplying energy to the electron beam at a frequency of: and storing the electron (including positron) beam in the orbit at a desired energy in the orbit. An insertion-type light source that forcibly changes an electron trajectory by the action of a magnetic field to emit radiated light; and a magnetic-field-intensity control unit that controls a magnetic-field intensity of the insertion-type light source. By controlling the magnetic field strength of the light source,
By adjusting the electron trajectory in the insertion type light source, the circulating frequency of the electrons circulating in the electron storage ring is adjusted.

With this configuration, the orbit of the electron beam when passing through the insertion type light source can be controlled by adjusting the magnetic field intensity of the insertion type light source. Can be absorbed, and as a result, the circulating frequency of electrons can be adjusted.

According to a second aspect of the present invention, there is provided an electron circulating frequency control device for an electron storage ring, comprising: a plurality of bending electromagnets for deflecting an electron trajectory at a desired deflection angle; and a high-frequency acceleration for supplying energy to an electron beam at a predetermined frequency. A wiggler inserted into the electron storage ring, wherein the wiggler is used to excite the wiggler. A power supply, and an excitation current amount control device that controls an excitation current amount supplied to the wiggler from the excitation power supply, and controls an excitation current amount of the wiggler to adjust an electron trajectory in the wiggler. Thus, the circulating frequency of the electrons circulating in the electron storage ring is adjusted.

With this configuration, by controlling the magnetic field strength of the wiggler, the length of the electron orbit when passing through the wiggler can be adjusted, and as a result, the orbital frequency of the electron storage ring can be controlled.

According to a third aspect of the present invention, there is provided an apparatus for controlling the orbital frequency of electrons in an electron storage ring, wherein an electron trajectory monitor for detecting the trajectory of an electron beam is arranged at a predetermined position on the electron storage ring.

With this configuration, the circulating frequency of the electrons can be adjusted by controlling the magnetic field of the wiggler while monitoring the trajectory of the electron beam, so that the control accuracy can be improved.

According to a fourth aspect of the present invention, there is provided an apparatus for controlling an orbiting frequency of electrons in an electron storage ring, comprising an arithmetic unit for calculating an amount of exciting current of a wiggler based on a position of an electron beam detected by the electron trajectory monitor. did.

With this configuration, the amount of excitation current for the wiggler can be immediately calculated based on the detection position of the electron beam, so that quick control is possible.

According to a fifth aspect of the present invention, there is provided an electron circulating frequency control device for an electron storage ring, comprising: an arithmetic device for calculating an amount of exciting current of the wiggler; and a frequency setting device for transmitting a frequency set value to the high-frequency accelerating cavity. And a central control device provided with

With such a configuration, even if the electron beam goes out of the design trajectory orbits when the orbiting frequency of the electron beam does not resonate with the frequency of the high-frequency accelerating cavity or the like, it is almost automatically generated. Then, the electron beam can be corrected to the design trajectory. Further, by disposing this central control device in a central control room or the like, it is possible to remotely control the trajectory of the electron beam.

According to a sixth aspect of the present invention, in the electron circulating frequency control device in the electron storage ring, a three-pole wiggler is used as the wiggler.

As described above, when a three-pole wiggler is used as the insertion type light source, the electron trajectory is the simplest, so that the trajectory calculation is easy and the control of the orbital frequency of the electrons can be easily performed.

In the electron trajectory correcting method according to the present invention, when the resonance frequency of the high-frequency acceleration cavity and the high-frequency power supplied to the high-frequency acceleration cavity deviate, first, the high-frequency acceleration cavity Second, the amount of displacement of the frequency of the high-frequency power supplied to the high-frequency acceleration cavity is detected, and secondly, the high-frequency acceleration is adjusted so that the frequency of the high-frequency acceleration cavity can be synchronized with the frequency of the high-frequency power. The frequency of the high-frequency power supplied to the cavity is changed, thirdly, the position of the electron beam is detected by the electron trajectory monitor, and fourthly, in the electron storage ring according to any one of claims 3 to 6, The setting of the amount of exciting current of the wiggler is changed by the circulating frequency control device of the electron so as to adjust the electron beam so as to pass through the design trajectory.

With this configuration, even when the resonance frequency of the high-frequency acceleration cavity is shifted from that of the high-frequency power supplied to the high-frequency acceleration cavity, the electron trajectory can be corrected without using a tuner. In addition, since no tuner is required, it is possible to use a high-frequency acceleration cavity without a tuner, and as a result, it is possible to simplify the structure of the high-frequency acceleration cavity and reduce maintenance work. Can be done.

[0066]

BEST MODE FOR CARRYING OUT THE INVENTION An orbiting frequency control device for an electron in an electron storage ring according to the present invention (hereinafter sometimes referred to simply as a "circulating frequency control device" for simplicity) and an electron orbit correction method (hereinafter referred to as an orbital correction method). Similarly, there may be a case where only the “correction method” is used.) An embodiment will be described. The following procedure will be used to facilitate understanding.

First, an outline of the present invention will be described in preparation for understanding the orbiting frequency control device of the present invention. Next, the basic configuration of the circulating frequency control device of the present invention will be described, and further, the basic operation of the circulating frequency control device of the present invention will be described. Lastly, a description will be given of a method of correcting an electron trajectory using the orbiting frequency control device of the present invention.

First, according to the above-described procedure, an outline of the orbiting frequency control device for electrons in the electron storage ring of the present invention will be described.
This will be described with reference to FIG. FIG. 4 is a characteristic diagram showing the relationship between the magnetic field strength of the wiggler, the displacement of the electron trajectory, and the traveling distance of the electron during the wiggler. In the figure, the magnetic field strength B (T) of the wiggler is shown by a continuous curve, and the displacement (mm) of the electron orbit is shown by a broken line.

As described above, when the frequency of the high-frequency accelerating cavity and the frequency of the high-frequency power supplied to this high-frequency accelerating cavity become inconsistent due to various factors, and it is necessary to tune, FIG. This is performed by changing the frequency of the high-frequency oscillator 152. At this time, the orbital frequency of the electrons changes, the orbital length of the electrons changes, the electrons orbit around the design orbit, and various problems such as a decrease in beam quality occur. As described above.

On the other hand, the insertion type light source inserted into the electron storage ring causes electrons to draw a desired trajectory by the action of a magnetic field, and generates light having higher luminance and specific characteristics than the bending electromagnet portion. Device. Therefore, if there is a means for controlling the magnetic field strength of the insertion type light source, it is possible to change the trajectory of electrons in the insertion type light source,
It is also possible to devise to absorb the displacement of the orbital length of the electrons.

For example, as the insertion type light source, a superconducting 3
Assuming that a polar wiggler is used, the electron incident on the wiggler is gently swung in the positive direction by the first magnetic pole, as shown in FIG. It is greatly swung in the positive direction by the two magnetic poles,
The third magnetic pole is designed to be gently swung in the negative direction and emitted to the designed orbit of the electron storage ring.

Since the amplitude of the electrons at this time changes depending on the magnetic field strength of the wiggler, the orbital length of the electrons passing through the wiggler can be adjusted by adjusting the amount of the excitation current supplied to the wiggler. . In other words, this means that by adjusting the amount of exciting current of the wiggler, the orbital length of the electrons can be changed to control the orbital frequency of the electrons.

That is, the basic principle of the device for controlling the orbital frequency of electrons in the electron storage ring of the present invention is that the high-frequency accelerating cavity and the high-frequency power supplied to the high-frequency accelerating cavity need to be synchronized. The change in the orbital length of the generated electrons is intended to be absorbed by controlling the magnetic field strength of an insertion type light source such as a wiggler.

Next, the basic configuration of the electron circulating frequency control device in the electron storage ring of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of an orbiting frequency control device for electrons in an electron storage ring according to the present invention. FIG. 2 is a plan view showing the arrangement of the main components of the orbiting frequency control device for electrons in the electron storage ring of the present invention.

As shown in FIG. 1, the orbiting frequency control device 10 of the present invention comprises a wiggler 90, an excitation power supply 92 for exciting the wiggler 90, and an excitation current amount supplied to the wiggler 90 by the excitation power supply 92. Is provided with an excitation current amount control device 94 for controlling the current. With these devices,
At least in principle, it is possible to control the orbital frequency of the electrons.

Further, the circulating frequency control device 10 of the present invention
In the embodiment, as shown in the plan view of FIG. 2, an electron trajectory monitor 30 for detecting the trajectory of the electron beam
A, 30B. These electron orbit monitors 3
2A, the electron beam actually circulates by detecting SR light emitted from the bending electromagnets 110A and 110B in the tangential direction of the orbit in the form of bremsstrahlung, as shown in FIG. This is to detect the trajectory that exists. If these electron trajectory monitors 30A and 30B are used, it is also possible to roughly estimate the deviation of the orbital frequency of electrons by the following procedure.

As described above, the speed of the electrons stored in the electron storage ring 100 may be considered to be a constant value of the light speed C _{0 in the} energy region where the electrons are stored. Therefore, the orbital frequency of the electron may be determined by the orbital length of the orbital electron actually orbiting.

On the other hand, the orbital length of the electron orbit is determined by the sum of the orbital lengths of the bending electromagnets 110A and 110B and the orbital length of the linear portion between the opposed bending electromagnets 110A and 110B. In the straight section,
The electrons travel substantially straight, except when passing through the wiggler 90. Therefore, the trajectory length in the straight line portion is wiggler 9
If the magnetic field strength of 0 is not changed, it can be considered as unchanged.

Accordingly, the displacement of the orbital length of the orbit of the electrons is remarkably exhibited in the bending electromagnets 110A and 110B, and the electron orbits in the bending electromagnets 110A and 110B are circular orbits.
By using 30B and detecting the radius of curvature of this orbit, the orbit length of the orbit of the electron can be roughly estimated.

Further, the orbiting frequency control device 10 according to the present embodiment includes an arithmetic device 20a for calculating the amount of exciting current of the wiggler 90 based on the positions of the electron beams detected by the electron trajectory monitors 30A and 30B, and FIG. High-frequency transmitter 152 of control device 150 for high-frequency acceleration cavity shown
And a central control device 20 having a frequency setting device 20b for giving a frequency setting value. The above is the basic configuration of the orbiting frequency control device 10 of the present invention, and the role of the central control device 20 will be described later.

Next, the basic operation of the electron circulating frequency control device 10 in the electron storage ring according to the present invention will be described with reference to FIGS.
FIG. 5 is a characteristic diagram showing the relationship between the magnetic field strength of the wiggler and the displacement of the orbital frequency of the electron beam. Note that this characteristic curve indicates that the electron storage ring 100 shown in FIG. 2 was operated under the operating conditions (perimeter 22 m, frequency 191.244 of the high-frequency accelerating cavity).
2 shows the relationship between the magnetic field strength (T) of the wiggler 90 and the displacement (kHz) of the orbital frequency of the electrons when operated at (MHz).

First, when the electron orbit monitors 30A and 30B detect that the orbital length of the electron has been displaced,
The detected electron trajectory data is transferred to the arithmetic unit 20a of the central control unit 20.

The arithmetic unit 20a calculates the orbital length of the electron beam according to the above-described procedure, and calculates the displacement of the orbital frequency of the electrons. Further, as shown by the characteristic curve in FIG. 5, since the relationship between the magnetic field strength of the wiggler 90 and the displacement of the circling frequency of the electron beam is stored in the arithmetic unit 20a, the magnetic field strength of the wiggler 90 and the The amount of the exciting current can be calculated. Then, as shown in FIG. 1, the current value setting signal is transmitted from the central control device 20 to the excitation current amount control device 94 of the wiggler 90.

As described above, when the magnetic field strength of the wiggler 90 is controlled, the displacement of the orbital frequency of the electron beam is absorbed by the wiggler 90, and the electron trajectory is substantially corrected to the design trajectory BL. In addition, by continuing to monitor the electron beam trajectory by the electron trajectory monitors 30A and 30B and finely adjusting the amount of exciting current of the wiggler 90, the electron trajectory can be accurately corrected to the design trajectory BL shown in FIG. it can.

Next, a method of correcting the trajectory of an electron beam by using the orbiting frequency control device 10 for electrons in the electron storage ring according to the present invention as shown in FIG. It will be described with reference to FIG. FIG. 3 is a flowchart for explaining a method of controlling the circulating frequency of electrons by using the circulating frequency control device for electrons in the electron storage ring of the present invention.

When the resonance frequency of the high-frequency accelerating cavity 140 shown in FIG. 2 is deviated due to the various causes described above, FIG.
As shown in (1), first, the tuning of the frequency of the high-frequency acceleration cavity 140 and the frequency of the high-frequency power supplied to the high-frequency acceleration cavity 140 is started (ST1).

Next, as described above, the signal from the directional coupler 159 shown in FIG.
And the frequency of the high-frequency power supplied to the high-frequency accelerating cavity 140 is detected (ST2), and based on the detected deviation from the frequency setting device 20b of the central control device 20 to the high-frequency transmitter 152. The frequency of the high-frequency oscillator 152 is changed by giving the calculated frequency setting value (ST3).

Then, actually, in the directional coupler 159,
It is detected whether the frequency of the high-frequency accelerating cavity 150 and the frequency of the high-frequency power have been synchronized (ST4). Here, if it is determined that the tuning is not performed, the frequency setting device 20b of the central control device 20 changes the frequency setting value of the high-frequency oscillator 152 again (ST3), and repeats until tuning can be performed.

On the other hand, if it is determined in step ST4 that the tuning has been achieved, the process proceeds to step ST5 to start correcting the deviation of the circulation frequency of the electrons. The deviation of the circulation frequency of the electrons is performed by the method described in the description of the basic operation of the circulation frequency control device 10 of the present invention described above. Therefore, although the description partially overlaps,
This will be briefly described with reference to the flowchart of FIG.

To correct the deviation of the orbital frequency of electrons,
First, as shown in FIG. 2, the beam trajectory monitors 30A and 30B arranged at predetermined positions detect SR light, thereby detecting the trajectory in which electrons actually orbit.

Next, monitoring is performed by the electron trajectory monitors 30A and 30B to determine whether or not the electron beam is on the design trajectory BL (ST6). And the design trajectory B
If not, the setting of the exciting current amount of the wiggler 90 is changed in ST7, and adjustment is performed by the method described above until the electron beam orbits the design trajectory (ST).
7).

When it is confirmed by the beam trajectory monitors 30A and 30B that the beam trajectory orbits on the design trajectory BL, the correction of the electron trajectory by the electron circulating frequency control device 10 in the electron storage ring of the present invention is performed. Complete (ST8).

Therefore, by using the above-described correction method, the deviation of the orbital frequency of the electrons caused when the frequency of the high-frequency accelerating cavity 140 is synchronized with the frequency of the high-frequency power is adjusted by adjusting the amount of the exciting current of the wiggler 90. By doing so, the electrons can be corrected so that the electrons orbit around the design trajectory BL.

The device for controlling the orbital frequency of electrons in the electron storage ring of the present invention is not limited to the above-described embodiment, but can be variously modified. First, in the above embodiment, an example in which a superconducting triode wiggler is used as an insertion type light source has been described. This is because the purpose of generating a strong magnetic field to emit light in a high energy region and the trajectory of an electron beam are the simplest. However, the gist of the present invention is to adjust the magnetic field strength of the insertion type light source to control the circulating frequency of the electron beam. Therefore, the present invention can be achieved by an insertion type light source provided with means capable of controlling the magnetic field intensity, and the present invention is not limited to a superconducting triode wiggler as an insertion type light source.

In the above embodiment, the orbit monitor of the electron beam has been described by measuring the SR light emitted from the electron and detecting the orbit of the electron. For example, a button-type beam monitor may be used. Further, the tuner may not be provided in the high-frequency accelerating cavity. However, it is natural that the present invention can be applied to an electron storage ring using the high-frequency accelerating cavity having the tuner.

In the above-described embodiment, the circulating frequency control device for the electron in the electron storage ring according to the present invention is used to correct the deviation of the circulating frequency of the electrons caused when the high-frequency accelerating cavity is synchronized with the high-frequency power. Although the description has been made on the assumption that it is used, it goes without saying that it may be used when such a situation occurs due to other factors.

[0097]

The circulating frequency control device for electrons in the electron storage ring according to the present invention has the following excellent effects because it is configured as described above. (1) As described in claim 1, in an electron storage ring, an insertion type light source inserted into the electron storage ring and forcibly changing an electron trajectory by the action of a magnetic field to emit radiated light. And a magnetic field intensity control means for controlling the magnetic field intensity of the insertion type light source. By controlling the magnetic field intensity of the insertion type light source and adjusting the electron trajectory in the insertion type light source, the inside of the electron storage ring is controlled. If the configuration is such that the circulating frequency of the circulating electrons is adjusted, the trajectory of the electron beam when passing through the insertion type light source can be controlled by adjusting the magnetic field strength of the insertion type light source. Can be absorbed, and as a result, the orbital frequency of electrons can be adjusted.

(2) As described in claim 2, in the electron storage ring, a wiggler inserted into the electron storage ring, an excitation power supply for exciting the wiggler, and a wiggler supplied from the excitation power supply are supplied to the wiggler. An exciting current amount control device for controlling the amount of exciting current, and controlling the amount of exciting current of the wiggler to adjust the electron trajectory in the wiggler, thereby adjusting the circulating frequency of the electrons circulating in the electron storage ring. With this configuration, the length of the electron orbit when passing through the wiggler can be adjusted by controlling the magnetic field strength of the wiggler, and as a result, the orbital frequency of the electron storage ring can be controlled.

(3) When the electron trajectory monitor for detecting the trajectory of the electron beam is arranged at a predetermined position on the electron storage ring, the trajectory of the electron beam can be monitored. Since the circling frequency of electrons can be adjusted by controlling the magnetic field of the wiggler, the control accuracy can be improved.

(4) As described in claim 4, based on the position of the electron beam detected by the electron trajectory monitor,
With a configuration including an arithmetic unit that calculates the amount of excitation current of the wiggler, the amount of excitation current of the wiggler can be calculated immediately based on the detection position of the electron beam, so that quick control becomes possible.

(5) As described in claim 5, a central control device is provided with a computing device for calculating the amount of exciting current of the wiggler and a frequency setting device for transmitting a frequency setting value to the high-frequency acceleration cavity. With this configuration, the electron beam can be designed almost automatically even if the electron beam goes out of the design trajectory when the circulating frequency of the electron beam does not resonate with the frequency of the high-frequency accelerating cavity. You will be able to correct it to orbit. (6) Further, by disposing the central control device in a central control room or the like, it is possible to remotely control the trajectory of the electron beam.

(7) As described in claim 6, when a three-pole wiggler is used as the wiggler, since the electron orbit is the simplest, the orbit calculation is easy and the control of the orbital frequency of the electron is easy. Can be done.

(8) On the other hand, in the electron trajectory correction method of the present invention, since the configuration is as described in claim 7, the resonance frequency of the high-frequency acceleration cavity and the high-frequency power supplied to the high-frequency acceleration cavity are shifted. In this case, the electron trajectory can be corrected without using a tuner. (9) Further, since it is not necessary to use a tuner, it is possible to use a high-frequency accelerating cavity without a tuner, and as a result, it is possible to simplify the structure of the high-frequency accelerating cavity and to reduce the maintenance. Effort can also be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an electron circulation frequency control device in an electron storage ring of the present invention.

FIG. 2 is a plan view showing an arrangement of a main configuration of an orbiting frequency control device for electrons in an electron storage ring of the present invention.

FIG. 3 is a flowchart for explaining a method of controlling the circulating frequency of electrons by using the circulating frequency control device for electrons in the electron storage ring of the present invention.

FIG. 4 is a characteristic diagram showing a relationship between a magnetic field strength of a wiggler, a displacement of an electron trajectory, and a traveling distance of electrons in the wiggler.

FIG. 5 is a characteristic diagram illustrating a relationship between a wiggler magnetic field intensity and a displacement amount of a circling frequency of an electron beam.

FIG. 6 is a plan view showing a schematic configuration of a conventional electron storage ring.

FIG. 7 is a perspective view of an essential part for explaining the principle of vibrating an electron beam largely by a wiggler.

FIG. 8 is a block diagram showing a schematic configuration of a control device of the high-frequency accelerating cavity of the electron storage ring.

FIG. 9 is a longitudinal sectional side view showing a state where the high-frequency accelerating cavity is attached to a beam duct for accumulating an electron beam.

10 is an enlarged vertical sectional side view of a portion indicated by A in FIG. 9;

[Explanation of Signs] 10: Electronic circulating frequency control device 20: Central control device 20a: Arithmetic device 20b: Frequency setting device 30A, 30B: Electron trajectory monitor 90: Wiggler (insertable light source) 92: Power supply for excitation 94: Excitation Current control device 100: electron storage ring 110A, 110B: bending electromagnet 140: high-frequency accelerating cavity BL: orbit

Claims (7)

[Claims] A plurality of bending magnets for deflecting an electron trajectory at a desired deflection angle; and a high-frequency accelerating cavity for supplying energy to the electron beam at a predetermined frequency. An electron storage ring adapted to accumulate at a desired energy therein; an insertion type light source which is inserted into the electron storage ring, forcibly changes an electron trajectory by the action of a magnetic field, and emits radiation. A magnetic field intensity control means for controlling the magnetic field intensity of the insertion type light source, by controlling the magnetic field intensity of the insertion type light source and adjusting the electron trajectory in the insertion type light source, the inside of the electron storage ring A circulating frequency control device for an electron in an electron storage ring, wherein a circulating frequency of circulating electrons is adjusted. 2. A deflecting electromagnet, comprising: a plurality of bending electromagnets for deflecting an electron trajectory at a desired deflection angle; and a high-frequency accelerating cavity for supplying energy to an electron beam at a predetermined frequency. A wiggler inserted into the electron storage ring, an excitation power supply for exciting the wiggler, and excitation to the wiggler supplied from the excitation power supply. An exciting current amount control device for controlling the amount of current, and controlling the exciting current amount of the wiggler to adjust the electron trajectory in the wiggler to adjust the circulating frequency of the electrons circulating in the electron storage ring. A frequency control device for electrons in an electron storage ring. 3. The electron circulating device according to claim 1, wherein an electron trajectory monitor for detecting the trajectory of the electron beam is arranged at a predetermined position of the electron storage ring. Frequency control device. 4. An arithmetic unit for calculating an amount of exciting current of a wiggler for correcting a circulating frequency of electrons based on a position of an electron beam detected by the electron trajectory monitor. A circulating frequency control device for electrons in an electron storage ring according to claim 1. 5. A central control device comprising: a calculating device for calculating an amount of exciting current of the wiggler; and a frequency setting device for transmitting a frequency setting value to the high-frequency accelerating cavity. 5. An electron circulating frequency control device in the electron storage ring according to 4. 6. The circling frequency control device for electrons in an electron storage ring according to claim 2, wherein a three-pole wiggler is used as said wiggler. 7. When the resonance frequency of the high-frequency acceleration cavity and the high-frequency power supplied to the high-frequency acceleration cavity deviate, first, the high-frequency acceleration cavity and the high-frequency supply to the high-frequency acceleration cavity Second, the frequency of the high-frequency power supplied to the high-frequency acceleration cavity is adjusted so that the frequency of the high-frequency acceleration cavity is synchronized with the frequency of the high-frequency power. Thirdly, the position of the electron beam is detected by the electron trajectory monitor, and fourthly, the excitation current of the wiggler by the circulating frequency control device for electrons in the electron storage ring according to any one of claims 3 to 6. A method for correcting the trajectory of electrons in an electron storage ring, characterized in that the setting of the amount is changed so that the electron beam passes through a designed trajectory.