JP2003287594A - X-ray generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an X-ray generator improving the X-ray generation efficiency. <P>SOLUTION: X rays called synchrotron radiation and visible rays are generated through the meandering of an electron beam e<SP>-</SP>when it passes between pairs of magnets 25a and 25b constituting an insertion light source 22 in an accelerator 21. The visible rays generated in the accelerator 21 oscillates laser by reciprocating in an optical system 23 composed of a first mirror 27, an asymmetrical mirror 29 and a second mirror 32. The X rays (γ rays) 28-1 are generated through the head-on collision of the oscillated laser light with the electron beam e<SP>-</SP>passing through the insertion light source 22. Since the laser light collides with the electron beam e<SP>-</SP>more frequently than in a conventional device, the generation efficiency of the X rays 28-1 is improved. The X rays 28-1 generated in the insertion light source 22 is emitted from the accelerator 21 and is reflected at an angle θ2 which is different from that of the laser light going along a light path 30 by the asymmetrical mirror 29. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] [0001] The present invention relates to an X-ray generator.
I do. [0002] 2. Description of the Related Art FIG. 4 is a diagram showing the principle of a conventional X-ray generator.
FIG. 5 is an enlarged view of the elliptical area A of FIG. An X-ray generator 1 shown in FIG.
Crotron radiation source (LSS), mainly laser light 2
Light source 3 that generates laser light, focuses laser light, collimates
Lens group 4 and an electron gun for generating an electron beam (Fig.
Not shown. ) And an accelerator that accelerates the electron beam (not shown).
Not. ) And collimate and collimate the electron beam from the accelerator
The four-pole magnet 5, the laser beam 2 and the electron beam
Compton cell 6 for collision and Compton cell
Electron beam passing through 6 and generated in Compton cell 6
Laser Compton scattering X-ray and electron beam separated
And a dipole 7. The Compton cell 6 shown in FIG.
8 and one side (left side in the figure) in the casing 8.
And a through-hole 9 is formed in the center,
Laser light 2 incident perpendicular to the hand direction is applied to the casing.
8. A first concave mirror that reflects and condenses light in the longitudinal direction
(The left side in the figure) 10 and the other side in the casing 8 (the figure
On the right), a through hole 11 is formed in the center,
The laser beam 2 from the first concave mirror 10
A second concave mirror that emits at right angles to the hand direction (right in the figure)
Side) 12 and enters from the other side of the casing 8
Electron beam e^-Are the through holes 9, 1 of the biconcave mirrors 10, 12.
1. In Compton cell 6
Is a laser beam 2 passing between the biconcave mirrors 10 and 12,
Electron beam e passing through through holes 9 and 11^-Collide with
It has become. [0005] Incidentally, 13 is an electron beam e^-Observe the position of
BPM (Beam Position Monitor)
14 is an electron beam e^-Steer to fine-tune the position of
It is a ring coil. 15 is the race in Compton cell 6.
16 is an IR camera for observing the light 2;
Electron beam e from Puton cell 6^-To observe
This is the Faraday Cup. 17 is a beryllium window
Yes, 18 observes X-rays separated by dipole 7
X-ray detector for [0006] SUMMARY OF THE INVENTION Compton
In the cell 6, the laser beam 2 and the electron beam e^-Is at first glance
Appears to collide, but not a complete head-on collision
The vehicle collides at a predetermined angle at a predetermined angle. This is both
If a perforated mirror like the concave mirrors 10 and 12 is used,
Optical axis of laser beam 2 and electron beam e^-Perfect match with the trajectory of
This is because it cannot be done. For this reason, laser
It is necessary to synchronize and amplify.
Since there are through holes 9 and 11, laser light is lost, and
However, there is a problem that the generation efficiency of X-rays is limited. Therefore, an object of the present invention is to solve the above problems.
To provide an X-ray generator with improved X-ray generation efficiency
It is to be. [0008] [MEANS FOR SOLVING THE PROBLEMS] To achieve the above object
The present invention provides an electron beam and a laser beam accelerated by an accelerator.
X-rays that generate X-rays by colliding with laser light from a source
In the generator, the linear electron beam trajectory in the accelerator
So that the directions of adjacent magnetic fields are alternated
Pairs of magnets that constitute an insertion light source
Placed on one extension of the linear electron beam trajectory outside
A first mirror for returning visible light from the insertion light source to the insertion light source
And the other extension of the linear electron beam trajectory outside the accelerator
The visible light reflection surface and the X-ray reflection surface are different.
From an asymmetric mirror and an asymmetric mirror located outside the accelerator
The visible light from the asymmetric mirror and return it to the insertion light source.
Causes laser oscillation, and the obtained laser light is
Laser inverse Compton scattering X-rays in frontal collision with a proton beam
And a second mirror for generating
You. According to the present invention, the insertion light source in the accelerator is configured.
A high-speed electron beam accelerated between multiple pairs of magnets
When passing through, the electrons meander and are called X
Generates lines and visible light. The visible light generated by the accelerator is
Light consisting of a first mirror, an asymmetric mirror and a second mirror
Laser oscillation occurs by reciprocating in the academic system (FEL, Fr
ee Electron Laser: Free Electron Ray
The). Laser light from this laser oscillation passes through the insertion light source
Collide with the rotating electron beam, causing laser inverse Compton scattering.
Irregular X-rays (γ-rays) are generated. Laser light and electron beam
Since the number of collisions increases compared to the conventional example, X-ray generation efficiency is improved.
Up. X-rays generated by the insertion light source exit from the accelerator
The light is reflected by the asymmetric mirror at an angle different from that of the laser light. [0010] Embodiments of the present invention will be described below.
This will be described in detail with reference to the drawings. FIG. 1 shows an embodiment of an X-ray generator according to the present invention.
FIG. 2 is a conceptual diagram showing the state of the X-ray generator shown in FIG.
FIG. 3 is an explanatory view of an asymmetric mirror used in the device, and FIG.
FIG. 7 is a diagram showing a modification of the asymmetric mirror shown in FIG. The X-ray generator 20 shown in FIG.
Beam e^-An electron gun (not shown) that generates
Ome e^-Accelerator 21 for accelerating and placed in accelerator 21
And the optical system 23.
You. The insertion light source 22 has a linear shape inside the accelerator 21.
Adjacent magnetic fields sandwiching the electron beam orbit (optical path) 24
Pairs of magnets arranged so that their directions are alternated
25a and 25b. The optical system 23 has a linear power supply outside the accelerator 21.
On the extension of one (right side in the figure)
Laser light that passes through the optical path 26 from the insertion light source 22
Through the input / output window (not shown) of the accelerator 21
A first mirror 27 returning to the source 22 and a straight line outside the accelerator 21
Extension of the other (right side in the figure) of the electron beam trajectory 24
And an entrance / exit window (not shown) of the accelerator 21.
Laser light passing through the optical path from the insertion light source 22 through the
An asymmetric mirror 29 on which the line 28-1 is incident;
The light path 31 is reflected by the asymmetric mirror 29
The visible light reflecting surface 29a of the asymmetric mirror 29
With the second mirror 32 which is reflected back to the insertion light source 22
It is configured. Each mirror 27, 29, 3 of the optical system 23
The optical axis adjustment 2 is performed by a geared motor or
This is performed by a ping motor. Note that L_naIs the visible light of the asymmetric mirror 29
The normal to the launch surface 29a, L_nxIs the X of the asymmetric mirror 29
This is a normal line of the line reflection surface 29b. As shown in FIG. 2, the asymmetric mirror 29 is a crystal.
(For example, Be) and a laser passing through the optical path 30
The visible light reflection surface 29a is a crystal surface (reflection of X-rays 28-1).
Surface) 29b so as to be inclined by an angle θ2.
ing. When generating γ-rays, the asymmetric
The mirror 29 becomes unnecessary and resonates at the position of the asymmetric mirror 29.
Mirror is arranged. Next, the operation of the X-ray generator shown in FIG.
This will be described with reference to FIG. The insertion light source 22 in the accelerator 21 shown in FIG.
Constituent pairs (8 pairs in the figure, but not limited
No. ) High-speed electrons accelerated between the magnets 25a and 25b
Beam e ^-Passes through the electron beam e^-Is affected by the magnetic field
X-rays and visible light called synchrotrons
appear. Of the visible light generated by the insertion light source 22,
Visible on the optical path 26 from the vessel 21 to the first mirror 27
The light is reflected by the first mirror 27 and returns to the accelerator 21,
After passing through the insertion light source 22, the asymmetric mirror 2
Go to 9. The visible light passing through the optical path 30 is reflected by the asymmetric mirror 29.
Incident on the optical path 30, the visible light on the optical path 30 is reflected by the visible light reflecting surface 29.
The light is reflected by a and goes to the second mirror 32. On the light path 31
The visible light is reflected by the second mirror 32 and is on the same optical path 31
And head toward the asymmetric mirror 29. Visible light on optical path 31
Is reflected by the visible light reflecting surface 29a of the asymmetric mirror 29.
A linear electron beam trajectory 24 passing through the same optical path 30
Through the optical path 26 to the first mirror 27. Sand
The visible light generated by the insertion light source 22 is reflected by the first mirror 2.
7, reflected by the asymmetric mirror 29 and the second mirror 32
Reciprocating the optical paths 24, 26, 30, 31 multiple times
More laser oscillation (FEL) occurs. This laser oscillation
Laser beam passes through a linear electron beam orbit 24
Electron beam e^-Inverse Compton scattering with head-on collision
X-rays (γ-rays) 28-1 are generated. Laser output is tens of M
Since it is about W, it can be used as an X-ray source. Leh
The light and electron beam e^-Number of collisions with
Therefore, X-ray generation efficiency is improved. The X-ray 28-1 generated by the insertion light source 22 is
The light exits from the gearbox 21 and travels toward the asymmetric mirror 29. Here, in FIG.
Laser light and X-rays generated in a linear electron beam orbit 24
28-1 on the visible light reflecting surface 29a of the asymmetric mirror 29
Both are incident at an incident angle θ1, but the laser passes through the optical path 30.
The light is reflected at the reflection angle θ1 on the visible light reflection surface 29a.
On the other hand, the X-ray 28-1 is reflected at the X-ray reflection surface (crystal surface) 29b.
The light is reflected at an angle of incidence θ3 (Bragg diffraction). The distance between the crystal planes 29b is d, and the X-ray 2
The wavelength of 8-1 and 28-2 is λ, and the crystal of X-ray 28-1 is
When the incident angle with respect to the surface 29b is (θ1 + θ2),
The wavelength λ of the X-ray 28-1 is less than 2 dsin (θ1 + θ2).
It is supposed to help. That is, the X-ray generator 20 shown in FIG.
Represents visible light or laser light reciprocating in the optical system 23.
Of which, the laser light traveling on the optical path 31 by the asymmetric mirror 29 is
X-rays 28-2 are reflected at different angles θ2
I have. The laser is a FEL (Free Electror).
on Laser: Free electron laser)
The laser wavelength is obtained continuously. As a result, the accelerator 21
Not only the stored energy of the laser but also the oscillation laser wavelength of the FEL
Can be changed, so that X-rays of any wavelength can be generated.
You. FIG. 3 shows a modification of the asymmetric mirror shown in FIG.
FIG. This asymmetric mirror 40 is composed of a diffraction grating.
And a plurality of grooves 41 are formed at predetermined intervals on the reflection surface 40a.
Is formed. Even if such an asymmetric mirror 40 is used,
The same effect as the asymmetric mirror 29 shown in FIG. Next, the light is generated by the X-ray generator 20 shown in FIG.
X-rays will be described. The X-ray generator 20 shown in FIG.
And electron beam e^-Not only make a head-on collision, but also
° Collide (rear impact). However, a 180 ° collision is a mirror
Not diffracted (the energy of X-rays generated during a head-on collision is 5
Assuming 0 keV, the energy generated by electromagnetic waves at the time of a 180 ° collision
The energy is only 1 eV. However, stored energy 5
This is the case of 3 MeV and a laser wavelength of 1 μm. ). The energy Er of the generated X-ray is represented by the following equation (1).
The generated laser wavelength is expressed by equation (2). [0030] (Equation 1) [0031] (Equation 2) Stored energy E = 53 MeV, λ1 = 1
μm, λu = 22 mm, K = 0.26 (Gap = 2
0 mm), which is feasible. [0033] In summary, according to the present invention, the generation of X-rays
To provide an X-ray generator with improved production efficiency
Can be.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a conceptual diagram showing an embodiment of an X-ray generator according to the present invention. FIG. 2 is an explanatory diagram of an asymmetric mirror used in the X-ray generator shown in FIG. FIG. 3 is a diagram showing a modification of the asymmetric mirror shown in FIG. FIG. 4 is a principle diagram of a conventional X-ray generator. FIG. 5 is an enlarged view of an elliptical area A of FIG. DESCRIPTION OF SYMBOLS 20 X-ray generator 21 Accelerator 22 Insertion light source 23 Optical system 24 Linear electron beam orbit (optical path) 25a, 25b Magnets 26, 30, 31 Optical path 27 First mirror 29 Asymmetric mirror 32 Second mirror

Claims (1)

Claims: 1. An X-ray generating an X-ray by colliding an electron beam accelerated by an accelerator with a laser beam from a laser light source.
In the line generator, a plurality of pairs of magnets constituting an insertion light source, which are arranged so that the directions of adjacent magnetic fields sandwich the linear electron beam trajectory in the accelerator and are alternated,
A first mirror that is arranged on one extension of the linear electron beam trajectory outside the accelerator and returns visible light from the insertion light source to the insertion light source; and the other of the linear electron beam trajectory outside the accelerator. An asymmetric mirror that is disposed on an extension of and has a reflection surface for visible light and an X-ray reflection surface different from each other, and that is disposed outside the accelerator and reflects visible light from the asymmetric mirror to the asymmetric mirror and returns the light to the insertion light source. An X-ray generator comprising: a second mirror for generating laser oscillation thereby causing the obtained laser beam to collide head-on with the electron beam to generate a laser inverse Compton scattered X-ray. .