JP3460867B2 - Undulator and intensity control system for undulator radiation - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an undulator and an undulator radiation intensity control system,
More specifically, it is suitable for use in controlling the intensity of undulator radiation of wavelengths in the X-ray region at high speed,
The present invention relates to an undulator and an undulator synchrotron radiation intensity control system that can be used in various X-ray application techniques such as X-ray lithography and X-ray structural analysis of substances.

[0002]

BACKGROUND OF THE INVENTION In an electron beam storage ring in a large synchrotron radiation facility, a portion where the electron beam goes straight between a bending electromagnet for bending the trajectory of the electron beam is called an undulator or a wiggler. By inserting a group of permanent magnets or a group of superconducting electromagnets, it is possible to take out emitted light with higher brightness and emitted light with shorter wavelength.

FIG. 5 shows a schematic structure of such a conventional undulator.
Includes a pair of undulator magnetic poles 102a and 102b.

These undulator magnetic poles 102a, 1
02b is configured by arranging a large number of permanent magnets so that the S poles and the N poles are regularly and alternately continuous, and the S pole (or N pole) of the undulator magnetic pole 102a and the N pole of the undulator magnetic pole 102b ( (Or S pole) are arranged so as to face each other.

In the above structure, when the electron beam passes through a magnetic field formed by regularly arranging a large number of permanent magnets by the undulator magnetic poles 102a and 102b,
The orbit of the electron is meandered many times, and synchrotron radiation is generated each time. The emitted lights thus generated overlap and interfere very strongly so that only light of a specific wavelength can be obtained with high brightness. The wavelength of the light thus obtained includes the wavelength in the X-ray region.

The high-luminance light of a specific wavelength emitted from the undulator as described above is referred to as "undulator radiation light" in the present specification.

Since such undulator radiation has a remarkably high brightness as compared with synchrotron radiation (SOR), undulator radiation having a wavelength in the X-ray region has been attracting attention as a new X-ray source. There is.

[0008]

However, in the prior art, there was no suitable intensity modulation method for the undulator radiation of the wavelength in the X-ray region generated by the undulator. There is a problem that the strength cannot be controlled.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to easily control the intensity of undulator radiation light having a wavelength in the X-ray region. An object of the present invention is to provide an undulator and an undulator radiation intensity control system capable of controlling the undulator.

[0010]

In order to achieve the above object, the undulator and the undulator radiation intensity control system according to the present invention change the wavelength of the undulator radiation when the characteristic value K of the undulator is changed. It was made paying attention to the knowledge that it changes.

That is, by using an electric field in addition to the undulator magnetic field, an undulator capable of easily controlling the characteristic value K of the undulator at a high speed is constructed, and the undulator radiation from this undulator is Bragg reflected. The wavelength of the undulator radiation that is incident on the single crystal plate that causes the undulator radiation is changed by controlling the characteristic value K of the undulator, and the undulator radiation that satisfies the Bragg reflection condition by the undulator is obtained. The light generation time is controlled to control the intensity of the undulator radiation light that is Bragg-reflected.

More specifically, the undulator according to the present invention is constructed by arranging a large number of permanent magnets so that the S poles and the N poles are regularly and alternately continuous, and the S poles and the N poles face each other. And a pair of undulator magnetic poles for generating a predetermined undulator magnetic field, an electric field generating means capable of generating an electric field in a direction perpendicular to the undulator magnetic field generated by the undulator magnetic pole, and the electric field generating means. And an electric field having a predetermined strength by controlling the electric field generating means by the control means to generate an electric field having a predetermined strength in a direction perpendicular to the undulator magnetic field. The characteristic value K of the vibrator is changed.

Further, the intensity control system for undulator radiation according to the present invention is configured by arranging a large number of permanent magnets so that the S poles and the N poles are regularly and alternately continuous, and the S poles and the N poles are arranged. A pair of undulator magnetic poles which are arranged so as to face each other and generate a predetermined undulator magnetic field, an electric field generating means capable of generating an electric field in the vertical direction of the undulator magnetic field generated by the undulator magnetic pole, and An undulator having a control means for controlling an electric field generating means to generate an electric field of a predetermined intensity, and an undulator radiation light emitted from the undulator are incident to cause a Bragg reflection of the undulator radiation light. A crystal plate, the electric field generating means is controlled by the control means, and The undulator is generated by changing the characteristic value K of the undulator by changing the wavelength of the undulator radiation incident on the single crystal plate by generating an electric field of a predetermined intensity in the direction perpendicular to the duller magnetic field. By controlling the generation time of the undulator radiation light that satisfies the condition of Bragg reflection by the above, and controlling the intensity of the undulator radiation light Bragg reflected by the single crystal plate.

[0014]

The characteristic value K of the undulator is the sum of the characteristic value given by the undulator magnetic field by the undulator magnetic pole and the characteristic value given by the electric field generated by the electric field generating means. Therefore, the characteristic value K of the undulator can be controlled by appropriately controlling the strength of the electric field generated by the electric field generating means by the control means.

By controlling the characteristic value K of the undulator as described above, the wavelength of the undulator radiation can be controlled.

Therefore, the control means appropriately controls the intensity of the electric field generated by the electric field generating means to control the characteristic value of the undulator, and the wavelength of the undulator radiation is set to a wavelength that satisfies the Bragg reflection condition. By controlling the generation time of the undulator radiation that satisfies the condition of Bragg reflection by matching or not matching with, it becomes possible to control the intensity of the undulator radiation that is Bragg reflected.

[0017]

Embodiments of the undulator and the undulator radiation intensity control system according to the present invention will now be described in detail with reference to the drawings.

1 to 3 show an embodiment of an undulator according to the present invention, FIG. 1 is a schematic longitudinal section, and FIG. 2 is a transverse sectional view taken along line II-II. 3 is a cross-sectional view taken along the line III-III. It should be noted that the same or corresponding structures as those of the conventional undulator shown in FIG. 5 described above are denoted by the same reference numerals as those in FIG. 5, and detailed description thereof will be omitted.

That is, the undulator 10 has a vacuum duct 12 through which an electron beam passes between a pair of undulator magnetic poles 102a and 102b.

A cable 14 is provided in the vacuum duct 12.
Is connected to the control device 16 via the
The pair of positive side electrode 18a and negative side electrode 18b, which are configured to generate a magnetic field, generate an electric field E in a direction perpendicular to the undulator magnetic field B generated by the undulator magnetic poles 102a and 102b. It is arranged.

More specifically, these positive electrodes 18
a and the minus side electrode 18b, the plus side electrode 18a and the minus side electrode 18b so that the direction of the electric field E changes corresponding to the change of the direction of the undulator magnetic field B generated by the undulator magnetic poles 102a and 102b.
Are arranged side by side so that they are regularly and alternately continuous, and the plus side electrode 18a and the minus side electrode 1
8b and the undulator magnetic field B generated by the undulator magnetic poles are arranged to face each other in the vertical direction.

Here, it is known that it is indispensable to operate the undulator when the characteristic value K of the undulator is in the vicinity of "1" in order to obtain high-intensity undulator radiation by the undulator. .

Also, a pair of undulator magnetic poles 102.
undulator magnetic field B generated by a, 102b
The characteristic value K of the undulator given by
K _B ”, K _B = 0.0934 × λ ₀ (cm) × B (kG) (1) λ ₀ : undulator period length (adjacent S pole (or N pole) and S pole) Distance between poles (or N poles) B: An undulator magnetic field generated by a pair of undulator magnetic poles.

In the above formula (1), when the calculation is performed with "λ ₀ = 5 (cm)" as the period length of a general undulator, the undulator magnetic field B for obtaining "K _B = 1" is "B = 2.15 (kG) ", the undulator magnetic field B of this magnitude can be easily generated.

On the other hand, when the characteristic value K of the undulator provided by an electric field generated between the positive electrode 18a and negative electrode 18b to "K = K _E", K _E = 3.115 × 10 ^{- 4} × λ ₀ (cm) × E (kV) (2) E: Electric field, and the electric field for obtaining “K _E = 1” is “E = 64
2 (kV / cm) "is calculated.

However, since it is extremely difficult to stably generate such a high electric field strength in the vacuum duct 12, in the present invention, the characteristic value K _B of the undulator is given by the characteristic value K _B given by the undulator magnetic field B. “1” is set so as to substantially satisfy the above condition, and the characteristic value K _E given by the electric field is added to slightly change the characteristic value K of the undulator.

That is, in the above embodiment, the undulator magnetic field B which does not change with time is always applied by the undulator magnetic poles 102a and 102b, and the characteristic value K _B by the undulator magnetic field _B is given. The characteristic value K _B given by the undulator magnetic field B appropriately configures the undulator magnetic poles 102a and 102b so that the characteristic value K of the undulator substantially satisfies “K = 1”. Is set in advance.

In this state, a pulse voltage is applied to the plus side electrode 18a and the minus side electrode 18b through the cable 14 under the control of the control device 16 to generate a periodic electric field E perpendicular to the undulator magnetic field. Let When the electric field E is generated in this manner, the characteristic value K _E due to the electric field _E is given.

[0029] Therefore, the overall characteristic value K of the undulator 10, since the "K = K _B + K _E", only generates a small electric field E of the intensity to provide a small characteristic value K _E, The overall characteristic value K of the undulator 10 can be changed.

Since the change of the electric field E can be performed at high speed by the control of the control device 16, the comprehensive characteristic value K of the undulator 10 can also be changed at high speed.

Further, since the pulse voltage can be applied to each of the plus side electrode 18a and the minus side electrode 18b while being delayed in accordance with the electron moving speed, the undulator radiation can be obtained more efficiently. Will be able to.

Next, an embodiment of the intensity control system for undulator radiation according to the present invention will be described with reference to FIG.

FIG. 4 shows a part of the electron beam storage ring, and the undulator 10 according to the present invention described above is arranged between the bending electromagnets 20a and 20b.

The undulator 10 is configured to emit undulator radiation having a wavelength in the X-ray region, and the undulator radiation having a wavelength in the X-ray region emitted from the undulator 10 is Bragg. It is configured to be incident on the single crystal plate 22 that causes reflection.

The electron beam emitted from the undulator 10 continues to rotate around the electron beam storage ring.

The Bragg reflection conditions are as follows: λ = 2d · sin θ λ: wavelength of undulator radiation (wavelength in X-ray region) d: lattice constant of single crystal plate 22 causing Bragg reflection θ: incident angle ( The angle between the undulator radiation and the single crystal plate 22), and the undulator 10 has a comprehensive characteristic value K (=
The wavelength of the undulator radiation when K _B + K _E ) is λ
Then, the lattice constant d of the single crystal plate 22 is set so that the condition of the Bragg reflection of “λ = 2d · sin θ” is exactly satisfied.
And the incident angle θ.

In the above structure, a pulse voltage is applied to the plus side electrode 18a and the minus side electrode 18b via the cable 14 under the control of the control device 16, and the undulator magnetic field B and the periodic electric field E in the vertical direction are applied. When the electric field E is generated, a characteristic value K _E is given by the electric field E.
(= K _B + K _E ), and undulator radiation of wavelength λ is emitted to the single crystal plate 22.

Since the undulator radiation with the wavelength λ satisfies the Bragg reflection condition as described above, the undulator radiation with the Bragg reflection is applied to the target.

On the other hand, under the control of the control device 16, the application of the pulse voltage to the plus side electrode 18a and the minus side electrode 18b via the cable 14 is stopped, and the undulator magnetic field B and the electric field E which is periodic in the vertical direction. If is not given, it means that the characteristic value K _E by the electric field E is not given, the undulator 10 shows the characteristic value K _B, the undulator radiation wavelength is a single crystal plate 22 which is different from the wavelength λ Is emitted.

Since the undulator radiation having a wavelength different from the wavelength λ does not satisfy the Bragg reflection condition as described above, Bragg reflection does not occur,
The target is not exposed to the undulator radiation.

That is, the control device 16 controls the application of the pulse voltage to the plus side electrode 18a and the minus side electrode 18b via the cable 14 to change the characteristic value K of the undulator 10 by the electric field E. Thereby, the wavelength of the undulator radiation light incident on the single crystal plate 22 can be changed. Thereby, the generation time of the undulator radiation that satisfies the condition of Bragg reflection is controlled, and the intensity of the undulator radiation of the wavelength in the X-ray region that is Bragg reflected by the single crystal plate 22 and is irradiated to the target is arbitrarily set. Can be controlled.

Moreover, as described above, the change of the electric field E can be performed at high speed under the control of the control device 16, so that the comprehensive characteristic value K of the undulator 10 can also be changed at high speed. Therefore, the intensity of the undulator light having the wavelength in the X-ray region with which the target is irradiated can also be controlled at high speed. Therefore, the undulator light with a wavelength in the X-ray region irradiated to the target is
Can be pulsed.

The wavelength λ of the undulator radiation that exactly satisfies the Bragg reflection condition is determined by the Bragg reflection condition described above. In practice, however, the undulator radiation light has a wavelength within a predetermined allowable range. Will cause Bragg reflections.

Therefore, when it is desired to irradiate the target with complete ON / OFF pulsed undulator radiation, the characteristic value K _E to be given by the electric field E is not given, and the undulator 10's When the comprehensive characteristic value K is given only by the characteristic value K _B given by the undulator magnetic field B, the wavelength of the undulator radiation is not included in the wavelength within this allowable range. The total characteristic value K, the characteristic value K _B given by the undulator magnetic field _B, and the characteristic value K _E given by the electric field E may be set.

When the undulator radiation that completely satisfies the Bragg reflection condition is emitted to the single crystal plate 22, the undulator radiation by the strongest Bragg reflection is emitted to the target, and the allowable wavelength range is The intensity of the undulator radiation emitted to the target by the Bragg reflection becomes weaker as the wavelength is farther from the wavelength satisfying the Bragg reflection condition.

When the intensity of the electric field E is changed, the electric field E
Since the characteristic value K _E given by changes, the characteristic value K _E
Undulator radiation from the wavelength that completely satisfies the Bragg reflection condition to the wavelength in the allowable range by
If the undulator 10 can be radiated, the intensity of the undulator radiation light with which the target is irradiated can be controlled arbitrarily.

[0047]

Since the present invention is configured as described above, it is possible to control the characteristic value K of the undulator at high speed, thereby changing the wavelength of the undulator radiation at high speed. it can.

Furthermore, since the wavelength of the undulator radiation can be changed at high speed, the intensity of the undulator radiation of the wavelength in the X-ray region can be controlled at high speed.

Therefore, it becomes possible to control the intensity of X-rays which can be used in various X-ray utilization techniques such as X-ray lithography and structural analysis of substances by X-rays at high speed.

[Brief description of drawings]

FIG. 1 is a schematic vertical section showing an embodiment of an undulator according to the present invention.

FIG. 2 is a cross-sectional view taken along the line II-II of FIG.

3 is a cross-sectional view taken along the line III-III in FIG.

FIG. 4 is a schematic configuration diagram showing a part of an electron beam storage ring.

FIG. 5 is a schematic perspective view showing a conventional undulator.

[Explanation of symbols]

10,100 undulator 12 vacuum duct 14 cables 16 Control device 18a Positive electrode 18b Negative electrode 20a, 20b Bending electromagnet 22 Single crystal plate 102a, 102b Undulator magnetic pole

Claims (4)

(57) [Claims] 1. A plurality of permanent magnets are arranged side by side so that S poles and N poles are regularly and alternately continuous, and the S poles and the N poles are arranged so as to face each other,
A pair of undulator magnetic poles for generating a predetermined undulator magnetic field, an electric field generating means capable of generating an electric field in a direction perpendicular to the undulator magnetic field generated by the pair of undulator magnetic poles, and controlling the electric field generating means. A control means for generating an electric field of a predetermined strength, and controlling the electric field generation means by the control means to generate an electric field of a predetermined strength in a direction perpendicular to the undulator magnetic field to thereby obtain a characteristic value of the undulator. An undulator characterized by changing K. Where K = K _B + K _E K _B : Characteristic value of the undulator given by the undulator magnetic field generated by the pair of undulator magnetic poles K _E : Of the undulator given by the electric field generated by the electric field generating means Characteristic value 2. The undulator according to claim 1, wherein the electric field generating means generates a pulsed electric field. 3. A plurality of permanent magnets are arranged side by side so that the S poles and the N poles are regularly and alternately continuous, and the S poles and the N poles are arranged so as to face each other,
A pair of undulator magnetic poles for generating a predetermined undulator magnetic field, an electric field generating means capable of generating an electric field in a direction perpendicular to the undulator magnetic field generated by the pair of undulator magnetic poles, and controlling the electric field generating means. An undulator having a control means for generating an electric field of a predetermined intensity, and undulator radiation emitted from the undulator is incident, and a single crystal plate that causes Bragg reflection of the undulator radiation, The control means controls the electric field generation means to generate an electric field of a predetermined intensity in a direction perpendicular to the undulator magnetic field to change the characteristic value K of the undulator, and to make the undulator incident on the single crystal plate. By changing the wavelength of the undulator radiation, The undulator radiation light is characterized in that the generation time of the undulator radiation light satisfying the condition of Bragg reflection is controlled to control the intensity of the undulator radiation light Bragg reflected by the single crystal plate. Strength control system. Where K = K _B + K _E K _B : Characteristic value of the undulator given by the undulator magnetic field generated by the pair of undulator magnetic poles K _E : Of the undulator given by the electric field generated by the electric field generating means Characteristic value 4. The undulator radiation intensity control system according to claim 3, wherein the electric field generating means generates an electric field in a pulsed manner.