JPH05217697A - Electron storage ring and its operating method - Google Patents

Abstract

PURPOSE:To stably maintain the output of synchrotron radiation for a long period of time by compensating the decreased current value of stored beam on the time basis with increase of the energy of stored beam. CONSTITUTION:An electron storage ring 2 is composed of a sensing means 4 for the current value of an stored beam, a calculating means 5 to calculate the set value of stored beam energy relative to the current value of the stored beam, an adjusting means to control the energy of the stored beam, and a generating means for synchrotron radiation. The calculating means 5 receives a current value signal 10 sensed by the sensing means 4, calculates the energy increasing amount of stored beam necessary for setting off the decreased current value of stored beam on the time basis, transmits the set signals 11, 12, 13 to adjusting means 6, 7, 8 to increase the energy of the stored beam, and thereby maintains the output of the radiation stably. Concretely described, the energization currents for a deflecting electric magnet 7 and quadruple electromagnet 8 are increased in compliance with the decreased current value of stored beam on the time basis, and the set signals 12, 13 are set so that the magnetic field of each magnet increases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron storage ring for deflecting a high-energy electron beam by a magnetic field to emit synchrotron radiation and a method of operating the same, and more particularly to radiation accompanied with a temporal decrease in the current value of the electron beam. The present invention relates to an electron storage ring suitable for suppressing a decrease in light output and an operating method thereof.

[0002]

2. Description of the Related Art A technique utilizing synchrotron radiation emitted from an electron storage ring has been attracting attention as a light source for semiconductor lithography. When using this technique, a stable synchrotron radiation output that guarantees a constant throughput is required. In order to keep the output of the synchrotron radiation stable, it is necessary to control the current value of the electron beam accumulated in the ring to a constant value, but in reality, this current value decreases with the passage of time. Will end up. Therefore, conventionally, in response to the temporal decrease in the current value of the electron beam, a new electron beam is sequentially additionally injected into the ring to operate so that the current value of the accumulated beam becomes constant. As a conventional device of this kind,
Vol. 3, No. 2, pp. The "Soltech 1 GeV radiation source facility" described in 17-32 is mentioned.

[0003]

In order to prevent the current value of the accumulated beam from decreasing by additionally injecting a new electron beam into the electron accumulation ring as in the above-mentioned prior art,
It is necessary to prepare a large-scale pre-accelerator and increase the energy of the additional electron beam by this pre-accelerator to an energy almost equal to that of the electron beam in the storage ring. In other words, it is necessary to use a full energy injection system. This full-energy injection method requires a large-scale pre-accelerator, which is a problem from the viewpoint of system size reduction and cost reduction.

On the other hand, in a system adopting a low energy injection method which requires only a small pre-accelerator, an electron beam whose energy has been increased by the pre-accelerator is injected into a storage ring and the energy of the electron beam is further increased in the storage ring. It is like this. Therefore, even if a low energy electron beam is to be additionally injected into the ring from the preceding stage accelerator,
This is impossible because electron beams having different energies have different trajectories in the ring. In a system that adopts the low energy injection method, if the electron beam is additionally injected from the pre-accelerator to suppress the decrease in the electron beam current value, the electron beam energy in the storage ring is additionally injected at the time of the additional injection. It is necessary to reduce the energy to the above energy, and it is necessary to frequently repeat re-injection, re-acceleration, and re-accumulation. This has many problems from the viewpoint of reliability as a stable light source and operating rate, and cannot be adopted.

An object of the present invention is to provide an electron storage ring and a method of operating the same which can maintain the output of synchrotron radiation light stably for a long time after the electron beam storage.

[0006]

The above object is achieved by compensating for the temporal decrease in the current value of the accumulated beam by increasing the energy of the accumulated beam. That is,
The electron beam is stored in the ring at an energy that is less than the maximum energy that can be accelerated, and the surplus acceleration capacity of the electron storage ring compensates for the decrease in the synchrotron radiation output due to the temporal decrease in the current value of the accumulation beam, and the synchrotron radiation output. Keep stable.

More specifically, the energy of the accumulated beam is increased by increasing the exciting current of the electromagnet and increasing the strength of the deflection magnetic field and the converging / diverging magnetic field in accordance with the temporal decrease of the current value of the accumulated beam. To do.

In addition to increasing the deflection magnetic field and the converging / diverging magnetic field strength in accordance with the temporal decrease in the current value of the accumulated beam, the acceleration voltage of the high frequency acceleration cavity is increased.

Further, in the case of adopting the full energy injection method, the above operating method is also used when additionally injecting,
Maintains stable synchrotron output.

[0010]

FIG. 2 is a graph showing the dependence of the emitted light spectrum on the energy of the accumulated beam. When the energy of the accumulated beam is increased to E1, E2, ... Under a constant current value, the synchrotron radiation output is enhanced in the short wavelength region near the peak wavelength and below, and near the peak wavelength of the synchrotron radiation output, The radiated light output, that is, the number of photons, increases in proportion to about the 7th power of beam energy. The emitted light output is proportional to the current value of the accumulated beam. Therefore, if the wavelength range used by the emitted light is set to the above wavelength range, the decrease in the emitted light output due to the decrease in the current value of the accumulated beam can be efficiently compensated by the increase in the energy of the accumulated beam.

FIG. 3 is a graph showing a radiant light spectrum when the decrease in the radiant light output due to the decrease in the current value of the accumulated beam is compensated for by the increase in the energy of the accumulated beam. The current value of the accumulated beam changes from the initial value I1 to I2 over time.
When the energy of the accumulated beam is increased from the initial value E1 to E2, the integrated value of the radiated light output P in the wavelength range λ1 to λ2 used by the radiated light can be made substantially constant.

The energy loss of the accumulated beam due to the emission of synchrotron radiation is compensated by the acceleration of the high frequency acceleration cavity by the high frequency electric field. The electron beam orbits the storage ring in synchronism with the high frequency electric field of the high frequency accelerating cavity, and is synchronized with the phase in which the accelerating electric field is applied to compensate the energy loss due to the emission of synchrotron radiation. Under this condition, the energy of the accumulated beam is kept constant.

When the exciting current of the electromagnet is increased and the strengths of the deflection magnetic field and the converging / diverging magnetic field are increased in accordance with the temporal decrease of the current value of the accumulated beam, the orbit of the electron beam shifts to the inside of the accumulation ring, and the orbit of the orbit is shifted. The length becomes shorter. as a result,
The orbit time of the electron beam is shortened, the synchronous phase of the beam in the high frequency acceleration cavity shifts to the side where the acceleration electric field increases,
The energy of the stored beam can be increased. The orbit of the electron beam returns to its original position due to this increase in energy, and the electron beam orbits the storage ring again in synchronization with the high frequency electric field of the high frequency acceleration cavity.

In accordance with the temporal decrease in the current value of the accumulated beam, the deflection magnetic field and the converging / diverging magnetic field strength are increased, and the accelerating voltage of the high frequency accelerating cavity is increased to increase the maximum value of the high frequency electric field and the above-mentioned value. The energy of the accumulated beam can be increased while keeping the ratio of the accelerating electric field in the synchronous phase constant.

Further, in the case where additional injection is possible by the full energy injection method, by adopting the above operating method between the additional injection of the beam, the above operating method can smooth the radiated light output even if the frequency of the additional injection is reduced. It is possible to keep the synchrotron radiation output stable by the chemical action.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an acceleration system according to an embodiment of the present invention. This accelerator system is composed of an electron storage ring 2 and its preceding stage accelerator 3. The electron storage ring 2 has a function of injecting a low-energy electron beam supplied from the pre-accelerator 3 and accelerating and storing up to the stored energy. The pre-stage accelerator 3 is, for example, a linac or a microtron, but in any case, it can be small.

The electron storage ring 2 controls the accumulated beam current value detecting means 4, the calculating means 5 for calculating the set value of the accumulated beam energy with respect to the accumulated beam current value, and the accumulated beam energy. It comprises adjusting means (high-frequency acceleration cavity 6, deflection electromagnet 7, quadrupole electromagnet 8) and means for generating synchrotron radiation (deflection electromagnet 7, insertion light source 9). However, the insertion light source 9 shall be installed as needed.

The calculating means 5 receives the current value signal 10 detected by the detecting means 4, calculates the energy increase amount of the accumulated beam necessary for canceling the temporal decrease of the accumulated beam current value, and the adjusting means 6 , 7 and 8 have setting signals 11 and 1, respectively.
2 and 13 to increase the energy of the accumulated beam,
Maintains stable synchrotron output. In this embodiment, the current value of the accumulated beam is detected by the detecting means 4, but the emitted light output is directly detected and the adjusting means 6, 7, 8 are controlled so that the emitted light output becomes constant. It can also be configured.

FIG. 3 is a synchrotron radiation spectrum diagram for explaining the calculation contents of the calculation means 5. The energy of the accumulated beam is increased temporally so that the integrated value of the emitted light output P between the wavelength regions λ1 and λ2 used by the synchrotron radiation becomes substantially constant according to the temporal decrease of the current value of the accumulated beam. To go. FIG. 3 illustrates the case where the current value of the accumulated beam decreases from the initial value I1 to I2 with time, and the energy of the accumulated beam increases correspondingly from the initial value E1 to E2.

Since the decrease in the synchrotron radiation output due to the temporal decrease of the accumulated beam current value is compensated by the increase of the accumulated beam energy and the synchrotron radiation output is maintained stable, the accumulated beam current value is temporally decreased. Accordingly, setting signals 12 and 13 are transmitted to increase the exciting currents of the deflection electromagnet 7 and the quadrupole electromagnet 8 and increase the strengths of the deflection magnetic field and the converging / diverging magnetic field.
Alternatively, depending on the temporal decrease of the accumulated beam current value,
The setting signals 11, 12 and 13 are transmitted so as to increase the intensity of the deflection magnetic field and the converging / diverging magnetic field and increase the acceleration voltage of the high frequency acceleration cavity 6. In the latter case, the height of the bucket, that is, the maximum value of the high-frequency electric field and the ratio of the acceleration electric field to the orbiting beam can be kept constant, so that the beam life determined by the acceleration voltage of the high-frequency acceleration cavity 6 can be kept above a certain level.

FIG. 4 is a synchrotron radiation spectrum diagram for explaining the calculation contents of the calculation means 5 when the monochromatic light from the insertion light source 9 is used. Even when the synchrotron radiation generating means is the insertion light source 9, the decrease in the radiation output due to the temporal decrease in the current value of the accumulated beam can be compensated by the increase in the energy of the accumulated beam. However, with this alone, the shift of the central wavelength to the short wavelength side due to the increase in the energy of the accumulated beam may pose a problem. In order to correct the deviation of the center wavelength, the magnetic field of the magnet group forming the insertion light source 9 may be increased. Therefore, when the monochromatic light from the insertion light source 9 is used, the calculation unit 5 calculates the magnetic field of the insertion light source, and transmits the setting signal 14 to the insertion light source 9. In FIG. 4, when the current value of the accumulated beam decreases from the initial value I1 to I2 with time, the energy of the accumulated beam increases correspondingly from the initial value E1 to E2, and the above-mentioned deviation of the center wavelength is corrected. Therefore, the case where the magnetic field of the insertion light source is increased from B1 to B2 is shown.

FIG. 5 is an electron storage ring operation pattern explanatory view for explaining an example of the operation method of the electron storage ring in the accelerator system adopting the low energy injection method.
In the present embodiment, after the electron beam is incident on the storage ring 2 and accelerated, the electron beam is accumulated with energy equal to or less than the maximum energy that can be accelerated, and the supply of synchrotron radiation light is started. afterwards,
The decrease in the emitted light output due to the temporal decrease in the current value of the accumulated beam is compensated by the increase in the energy of the accumulated beam, and the emitted light output is maintained stable. When the energy of the accumulated beam reaches the maximum energy that can be accelerated, the supply of synchrotron radiation is stopped, and the electron beam is re-injected, re-accelerated, and re-accumulated. Hereinafter, the above process is repeated. When the radiated light output is allowed to vary to some extent as the light source, the duration of the radiated light supply can be further extended within the allowable range.

FIG. 6 is a block diagram of an accelerator system according to an embodiment of the present invention which employs the full energy injection method. This accelerator system is composed of an electron storage ring 16 and its pre-stage accelerator 17. Electron storage ring 16
Has a function of injecting and accumulating an electron beam accelerated to the accumulated energy by the pre-stage accelerator 17. Front-stage accelerator 1
Reference numeral 7 is, for example, a synchrotron or a linac. Figure 6
Shows the case where the pre-stage accelerator 17 is a synchrotron. The structure of the electron storage ring 16 is basically the same as that of the electron storage ring 2 in the above embodiment.

FIG. 7 is an electron storage ring operation pattern explanatory diagram for explaining the operation method of the electron storage ring in the accelerator system shown in FIG. The electron beam accelerated to the accumulated energy by the pre-stage accelerator 17 is incident on and accumulated in the accumulation ring 16, and the supply of synchrotron radiation light is started. After that, the decrease in the emitted light output due to the temporal decrease in the current value of the accumulated beam is compensated by the increase in the energy of the accumulated beam, and the emitted light output is maintained stable. The operation method at that time is the same as that of the above-mentioned embodiment. When the energy of the accumulated beam reaches the maximum energy that can be accelerated by the accumulation ring 16, the supply of the synchrotron radiation light is temporarily stopped and the beam is additionally incident. In the additional injection, first, the energy of the accumulated beam is returned to the accumulated energy before the above compensation is performed, and then the electron beam accelerated to the accumulated energy by the pre-stage accelerator 17 is additionally incident on the accumulation ring 16 and the current of the accumulated beam is increased. Supply the reduced value.
Hereinafter, the above process is repeated. When the radiated light output is allowed to vary to some extent as the light source, the duration of the radiated light supply can be further extended within the allowable range.

FIG. 8 is a block diagram of a radiation exposure apparatus according to an embodiment of the present invention. The synchrotron radiation exposure apparatus includes an accelerator system 1 and an exposure apparatus 19. The light source of the synchrotron radiation may be the bending magnet 7 of the electron storage ring 2 or the insertion light source 9.
But good. FIG. 8 shows a case where the deflection electromagnet 7 is used as a light source. The calculation means 5 of the electron storage ring 2 sets the energy of the accumulated beam necessary for maintaining the radiated light output stably in accordance with the temporal decrease of the current value of the accumulated beam. The exposure device 19 receives the setting signal 20 of the emitted light output from the calculation means 5 and adjusts the exposure time.

The accelerator system 1 according to this embodiment is of a low energy injection type. Therefore, since additional injection is impossible, the current value of the accumulated beam at the time of completion of injection / acceleration cannot always be constant in the operation pattern shown in FIG. Therefore, the exposure time is adjusted for each period of each radiant light supply. Needless to say, the synchrotron radiation exposure method in this embodiment is also effective for an exposure apparatus that employs a full energy injection type accelerator system.

[0027]

According to the present invention, the decrease in the output of the synchrotron radiation due to the temporal decrease in the current value of the accumulated beam is compensated by the increase in the energy of the accumulated beam, and the output of the synchrotron emitted light is maintained for a long time. The electron storage ring can be stably maintained and the reliability of the electron storage ring as a stable light source can be improved.

Specifically, 50% of the current value of the accumulated beam
The drop can be compensated by a 10% increase in the energy of the stored beam. For example, when an electron storage ring with a stored beam life of 6 hours is allowed as a light source with a fluctuation in output of emitted light of up to 10%, the conventional method is to re-inject / re-accelerate / re-inject the beam once every 30 minutes. It needs to be accumulated again. On the other hand, according to the present invention, a constant radiant light output can be maintained for 4 hours or more with a facility margin of 10% increase in accumulated beam energy.

The present invention is particularly effective for a low energy injection type electron storage ring in which additional injection of a beam is impossible,
A small pre-accelerator will suffice, and it will greatly contribute to the practical application of the low-energy injection method, which makes it easy to downsize the system.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an accelerator system according to an embodiment of the present invention.

FIG. 2 is a graph showing the dependence of the emitted light spectrum on the energy of the accumulated beam.

FIG. 3 is a graph showing a spectrum of emitted light when a decrease in output of emitted light due to a decrease in current value of the accumulated beam is compensated by an increase in energy of the accumulated beam.

FIG. 4 is a synchrotron radiation spectrum diagram for explaining calculation contents of a calculation means when an insertion light source is used.

FIG. 5 is an electron storage ring operation pattern explanatory diagram illustrating an example of an operation method of an electron storage ring in an accelerator system adopting a low energy injection method.

FIG. 6 is a configuration diagram of an accelerator system according to an embodiment of the present invention that employs a full energy injection method.

7 is an electron storage ring operation pattern explanatory diagram illustrating an operation method of an electron storage ring in the accelerator system shown in FIG.

FIG. 8 is a configuration diagram of a radiation exposure apparatus according to an embodiment of the present invention.

[Explanation of symbols]

2, 16 ... Electron storage ring, 3, 17 ... Pre-stage accelerator, 4
... storage current value detection means, 5 ... calculation means, 6 ... high-frequency acceleration cavity, 7 ... deflection electromagnet, 8 ... quadrupole electromagnet, 9 ... insertion light source, 10 ... detection signal, 11-14, 20 ... setting signal, 1
9 ... Exposure device.

Claims (11)

[Claims] 1. An electron storage ring that emits synchrotron radiation by deflecting a high-energy electron beam with a magnetic field to reduce synchrotron radiation output decrease due to temporal reduction of current value of the accumulation beam by increasing energy of the accumulation beam. A method of operating an electron storage ring, which is characterized by compensating and maintaining the synchrotron radiation output stably. 2. An electron storage ring for deflecting a high-energy electron beam with a magnetic field to supply synchrotron radiation light, stores the electron beam with energy smaller than the maximum energy that can be accelerated, and uses the surplus accelerating ability of the accumulated beam. A method for operating an electron storage ring, characterized in that a decrease in synchrotron radiation output due to a temporal decrease in current value is compensated by an increase in accumulated beam energy to stably maintain synchrotron radiation output. 3. The electron storage ring according to claim 1, wherein the exciting current of the electromagnet is increased and the strengths of the deflection magnetic field and the converging / diverging magnetic field are increased in accordance with the temporal decrease of the current value of the accumulated beam. Driving method. 4. The acceleration voltage of a high frequency accelerating cavity according to claim 1, in addition to the increase of the deflection magnetic field and the converging / diverging magnetic field strength according to claim 3, in response to the temporal decrease of the current value of the accumulated beam. A method for operating an electron storage ring, comprising: 5. An electron storage ring for deflecting a high-energy electron beam with a magnetic field to emit synchrotron radiation, the method of operation according to claim 1, and a beam accelerator for maintaining a current value of the stored beam. A method of operating an electron storage ring, which is characterized in that synchrotron radiation output is stably maintained by using additional incidence. 6. A means for detecting the current value of the accumulated beam, and an arithmetic means for calculating the energy of the accumulated beam necessary for maintaining a stable radiant light output according to the temporal decrease of the current value of the accumulated beam. An electron storage ring having an adjusting means for controlling the energy of the accumulated beam based on the calculation result and a radiant light generating means. 7. Synchrotron radiation output detection means, calculation means for calculating the energy of the accumulated beam required to maintain stable radiation light output, and adjustment for controlling the energy of the accumulated beam based on the calculation result. An electron storage ring comprising means and means for generating emitted light. 8. An electron storage ring that emits synchrotron radiation by deflecting a high-energy electron beam with a magnetic field, which is necessary for maintaining stable radiation light output in accordance with the temporal decrease of the current value of the accumulation beam. Electron storage ring control device characterized in that the energy of the accumulated beam is calculated and the energy of the accumulated beam is controlled. 9. A radiation exposure method using an electron storage ring as a light source, wherein the exposure time is adjusted according to the current value and energy of the accumulated beam. 10. An electron storage ring for deflecting a high-energy electron beam with a magnetic field to emit synchrotron radiation by reducing the emitted light output due to the temporal decrease of the current value of the accumulated beam by increasing the energy of the accumulated beam. An electron storage ring comprising means for compensating and maintaining the synchrotron radiation output stable. 11. An electron storage ring according to claim 10,
Exposure means for performing exposure by using synchrotron radiation light extracted from the electron storage ring as an exposure source, and an amount of increase in energy of the accumulated beam increased in accordance with a temporal decrease in current value of the accumulated beam in the electron storage ring. And an exposure time adjusting means for adjusting the exposure time in the exposure means according to the stable time of the output of the radiant light determined by.