JPH0882700A - Undulator and intensity control system for undulator radiation - Google Patents

Abstract

(57) [Summary] [Object] To make it possible to easily control the intensity of undulator radiation having a wavelength in the X-ray region. A pair of undulator magnetic poles 102a and 102b for generating a predetermined undulator magnetic field B, a plus electrode 18a capable of generating an electric field in a direction perpendicular to the undulator magnetic field B generated by the undulator magnetic poles 102a and 102b, and A negative electrode 18b;
An undulator 10 having a control device 16 that controls the plus side electrode 18a and the minus side electrode 18b to generate an electric field of a predetermined intensity, and undulator radiation emitted from the undulator 10 are incident, and undulator radiation Single crystal plate 2 that causes Bragg reflection of light
And 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an undulator and an intensity control system for undulator radiation.
More specifically, it is suitable for use when controlling the intensity of undulator radiation having a wavelength in the X-ray region at a high speed,
The present invention relates to an undulator and an intensity control system of undulator radiation that can be used in various X-ray utilization techniques such as X-ray lithography and structural analysis of a substance by X-rays.

[0002]

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

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

[0004] These undulator magnetic poles 102a, 1
Reference numeral 02b denotes a structure in which a number of permanent magnets are arranged so that the S pole and the N pole are regularly and alternately continuous. The S pole (or N pole) of the undulator magnetic pole 102a and the N pole (or N pole) of the undulator magnetic pole 102b Or the S pole) are arranged to face each other.

In the above configuration, when an electron beam passes through a magnetic field formed by regularly arranging a number of permanent magnets formed by undulator magnetic poles 102a and 102b,
The trajectory of the electron is meandered many times, each time generating an emitted light. The emitted light thus overlapped and interfered very strongly, so that only light of a specific wavelength could be obtained with high brightness. The wavelength of the light thus obtained includes the wavelength in the X-ray region.

[0006] The high-luminance light of a specific wavelength emitted from the undulator as described above is referred to as "undulator radiation" in this specification.

Since such undulator radiation has much higher brightness than synchrotron radiation (SOR), undulator radiation having a wavelength in the X-ray region has attracted attention as a new X-ray source. I have.

[0008]

However, in the prior art, there has not been a proper method of modulating the intensity of the undulator radiation light having a wavelength in the X-ray region generated by the undulator. There was a problem that intensity control could not be performed.

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

[0010]

In order to achieve the above object, the undulator and the intensity control system of the undulator radiation light according to the present invention, when the characteristic value K of the undulator is changed, the wavelength of the undulator radiation light is changed. It was made focusing on 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 formed, and the undulator radiation light from this undulator is subjected to Bragg reflection. The undulator radiation that satisfies the condition of Bragg reflection by the undulator by changing the wavelength of the undulator radiation light incident on the single crystal plate to be caused and incident on the single crystal plate by controlling the characteristic value K of the undulator The intensity of the undulator radiation light reflected by the Bragg is controlled by controlling the light generation time.

More specifically, the undulator according to the present invention is constituted by arranging a large number of permanent magnets so that S poles and N poles are regularly and alternately continued, and the S pole and the N pole face each other. A pair of undulator magnetic poles arranged to generate 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 Controlling the electric field generation means by the control means to generate an electric field of a predetermined intensity in the vertical direction of the undulator magnetic field. The characteristic value K of the radiator is changed.

Further, the undulator radiation light intensity control system according to the present invention is constituted by arranging a large number of permanent magnets so that the S pole and the N pole are regularly and alternately continued, and the S pole and the N pole are connected to each other. Are disposed so as to face each other, a pair of undulator magnetic poles for generating a predetermined undulator magnetic pole, and an electric field generating means capable of generating an electric field in a vertical direction of the undulator magnetic field generated by the undulator magnetic pole, An undulator having control means for controlling the electric field generating means to generate an electric field of a predetermined intensity; and a undulator radiated light emitted from the undulator being incident thereon and causing Bragg reflection of the undulator radiated light. A crystal plate, the electric field generating means being controlled by the control means, By generating an electric field of a predetermined intensity in the vertical direction of the undulator magnetic field to change the characteristic value K of the undulator and changing the wavelength of the undulator radiation light incident on the single crystal plate, the undulator And the intensity of the undulator radiation that is Bragg-reflected by the single crystal plate is controlled by controlling the generation time of the undulator radiation that satisfies the Bragg reflection condition.

[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, by appropriately controlling the intensity of the electric field generated by the electric field generating means by the control means, the characteristic value K of the undulator can be controlled.

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

For this reason, the control means controls the characteristic value of the undulator by appropriately controlling the intensity of the electric field generated by the electric field generation means, and adjusts the wavelength of the undulator radiation light to a wavelength satisfying the condition of Bragg reflection. When the generation time of the undulator radiation light that satisfies the Bragg reflection condition is controlled so as to match or not to the above, the intensity of the undulator radiation light that is Bragg reflected can be controlled.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an undulator and an intensity control system for undulator radiation according to the present invention will be described below in detail with reference to the drawings.

FIGS. 1 to 3 show an embodiment of the 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 transverse sectional view taken along line III-III. Note that the same or corresponding components 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 is 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.
Connected to the control device 16 via the
A pair of plus side electrode 18a and minus side electrode 18b configured to 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, the positive electrode 18
a and the negative electrode 18b are connected to the positive and negative electrodes 18a and 18b so that the direction of the electric field E changes in response to the change in the direction of the undulator magnetic field B generated by the undulator magnetic poles 102a and 102b.
Are arranged side by side so as to be regularly and alternately continuous, and the plus side electrode 18a and the minus side electrode 1
8b are disposed so as to be vertically opposed to the undulator magnetic field B generated by the undulator magnetic pole.

Here, it is known that it is essential to operate the undulator when the characteristic value K of the undulator is near "1" in order to obtain high-brightness undulator radiation with the undulator. .

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

In the above equation (1), when the calculation is performed using “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) ", but an undulator magnetic field B of this magnitude can be easily generated.

On the other hand, assuming that the characteristic value K of the undulator given by the electric field generated between the plus side electrode 18a and the minus side electrode 18b is “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) ".

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

That is, in the above-described 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 KB by the undulator magnetic field _B is given. The characteristic value K _B provided by the undulator field B, so as to substantially satisfy the "K = 1" as the characteristic value K of the undulator, the size of the undulator field B constitute undulator magnetic pole 102a, 102b as appropriate Is set in advance.

In such a 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 it. When the electric field E is generated in this manner, a 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 electric field E can be changed at a high speed under the control of the control device 16, the overall characteristic value K of the undulator 10 can also be changed at a high speed.

Further, since the application of the pulse voltage to each of the plus side electrode 18a and the minus side electrode 18b can be performed while being delayed according to the moving speed of the electrons, undulator radiation can be obtained more efficiently. Will be able to

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

FIG. 4 shows a part of the electron beam storage ring, in which the above-described undulator 10 according to the present invention is disposed 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 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.

Here, the conditions of Bragg reflection 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 an overall characteristic value K (=
The wavelength of the undulator radiation at the time of the K _B + K _E) λ
Then, the lattice constant d of the single crystal plate 22 is set so as to exactly satisfy the condition of Bragg reflection of “λ = 2d · sin θ”.
And the incident angle θ.

In the above configuration, under the control of the control device 16, a pulse voltage is applied to the plus side electrode 18a and the minus side electrode 18b via the cable 14, and an electric field E that is periodic in the direction perpendicular to the undulator magnetic field B. Is generated, the characteristic value K _E is given by the electric field E, so that the undulator 10 has the overall characteristic value K _E.
(= K _B + K _E) indicates, undulator radiation at a wavelength λ is emitted to the single crystal plate 22.

Since the undulator radiation having the wavelength λ satisfies the Bragg reflection condition as described above, the target is irradiated with the Bragg-reflected undulator radiation.

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 periodic electric field E in the direction perpendicular to the undulator magnetic field B. 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 Radiated.

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

That is, under the control of the controller 16, the application of the pulse voltage to the plus side electrode 18a and the minus side electrode 18b via the cable 14 is controlled, and the characteristic value K of the undulator 10 is changed 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 light that satisfies the condition of Bragg reflection is controlled, and the intensity of the undulator radiation light having a wavelength in the X-ray region that is Bragg-reflected by the single crystal plate 22 and irradiated to the target is arbitrarily set. Can be controlled.

Further, as described above, the change of the electric field E can be performed at a high speed under the control of the control device 16, so that the overall characteristic value K of the undulator 10 can be changed at a high speed. Therefore, the intensity of the undulator light having a wavelength in the X-ray region irradiated on the target can be controlled at high speed. For this reason, undulator light having a wavelength in the X-ray region irradiated to the target is
It can be pulsed.

Although the wavelength λ of the undulator radiation light that exactly satisfies the Bragg reflection condition is determined by the above Bragg reflection condition, it is actually undulator radiation light having a wavelength within a predetermined allowable range. Will cause Bragg reflection.

Therefore, when it is desired to irradiate the target with complete ON / OFF pulsed undulator radiation, the characteristic value K _E given by the electric field E is not given, and the undulator 10 when overall characteristic value K is given by only the characteristic value K _B given by undulator field B, as the wavelength of the undulator synchrotron radiation is not included in the wavelength of the allowable range, the undulator 10 What is necessary is just to set the overall characteristic value K, the characteristic value KB given by the undulator magnetic field _B, and the characteristic value K _E given by the electric field E.

When the undulator radiation light that completely satisfies the Bragg reflection condition is radiated to the single crystal plate 22, the undulator radiation light due to the strongest Bragg reflection is radiated to the target, and the allowable wavelength range is changed. As the distance from the wavelength completely satisfies the condition of Bragg reflection, the intensity of undulator radiation emitted to the target by Bragg reflection decreases.

When the intensity of the electric field E changes, the electric field E
Since given characteristic value K _E is changed by the characteristic value K _E
, The undulator radiation from a wavelength that completely satisfies the condition of Bragg reflection to an acceptable wavelength,
If the target can be radiated from the undulator 10, the intensity of the undulator radiation emitted to the target can be arbitrarily controlled.

[0047]

Since the present invention is configured as described above, the characteristic value K of the undulator can be controlled at a high speed, whereby the wavelength of the undulator radiation light can be varied at a high speed. it can.

Further, since the wavelength of the undulator radiation can be varied at high speed, the intensity of the undulator radiation having a wavelength in the X-ray range can be controlled at high speed.

Therefore, the intensity of X-rays that can be used in various X-ray utilization techniques such as X-ray lithography and structural analysis of substances by X-rays can be controlled at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic longitudinal sectional view showing one embodiment of an undulator according to the present invention.

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

FIG. 3 is a cross-sectional view taken along line III-III of 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 Cable 16 Controller 18a Positive electrode 18b Negative electrode 20a, 20b Bending electromagnet 22 Single crystal plate 102a, 102b Undulator magnetic pole

Claims (4)

[Claims] A plurality of permanent magnets arranged so that an S pole and an N pole are regularly and alternately continuous; and the S pole and the N pole 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 undulator magnetic pole, Control means for generating an electric field of an intensity, and controlling the electric field generating means by the control means to generate an electric field of a predetermined intensity in a direction perpendicular to the undulator magnetic field, thereby setting a characteristic value K of the undulator. An undulator characterized by being changed. 2. The undulator according to claim 1, wherein said electric field generating means generates an electric field in a pulsed manner. 3. A structure in which a number of permanent magnets are arranged so that an S pole and an N pole are regularly and alternately continued, and the S pole and the N pole are arranged so as to face each other;
A pair of undulator magnetic poles for generating a predetermined undulator magnetic field, 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, An undulator having control means for generating a strong electric field, and a single crystal plate to which undulator radiation emitted from the undulator is incident and causes Bragg reflection of the undulator radiation, Means for controlling the electric field generating means to generate an electric field having a predetermined intensity in a direction perpendicular to the undulator magnetic field, thereby changing the characteristic value K of the undulator, and causing the undulator to be incident on the single crystal plate. By changing the wavelength of the emitted light, the The generation time of the undulator radiation light that satisfies the condition of reflection of the undulator, and the intensity of the undulator radiation light that is Bragg-reflected by the single crystal plate is controlled. Intensity control system. 4. The system for controlling the intensity of undulator radiation light according to claim 3, wherein said electric field generation means generates an electric field in a pulsed manner.