JPH06326423A - Generation of cyclobunching coherent radiation and device therefor - Google Patents

Abstract

(57) [Summary] [Purpose] It is possible to generate coherently polarized high-intensity synchrotron radiation from the millimeter wave to the X-ray region without a large accelerator and electron beam storage ring. [Structure] The accelerated electron beam is obliquely introduced to the axis of the solenoid magnetic field, and the cyclotron resonance high-frequency cavity mounted in the magnetic field causes resonance in the cyclotron rotation of the electrons to induce the rotation phase bunching. so,
A device that extracts bunching electrons as an ultra-short pulse beam outside the solenoid magnetic field and passes them through a synchrotron radiation generation wiggler or undulator or a transition radiation light generation thin film to generate cyclobunching coherent radiation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and a device for generating cyclobunching coherent radiation in the millimeter wave to X-ray region.

[0002]

2. Description of the Related Art It is well known that synchrotron radiation is useful not only in the short wavelength region such as X-rays and vacuum ultraviolet light, but also in the long wavelength region of far infrared rays. There is a practical problem that the intensity is weak because the spectral intensity decreases with the fourth power of the wavelength. On the other hand, synchrotron synchrotron radiation and free electron lasers require large accelerators and electron storage rings, so regional restrictions are imposed on the spread of synchrotron radiation science and technology.

[0003]

The problems to be solved are that it is difficult to obtain high-intensity radiant light over a wide range from the millimeter wave to the X-ray region by the conventional technique, and the radiant light source is a large facility, This is a major obstacle to the spread of synchrotron radiation science and technology.

[0004]

According to the present invention, a part of accelerated electron energy is converted into a swirl energy in a solenoid magnetic field, and a swirl phase bunching caused by a relativistic effect in a swirl motion is used to generate an ultrashort pulse. After the bunching electron beam is generated, it is guided to a synchrotron radiation generating magnet or thin film, and coherent synchrotron radiation with a wavelength similar to the spatial spread of bunching electrons in the traveling direction is obtained with an intensity that cannot be obtained by conventional methods. It is characterized by being generated by.
That is, the conventional synchrotron radiation ring or free electron laser incorporates a huge amount of electron beam control equipment including auxiliary acceleration in addition to synchrotron radiation or laser generation equipment such as wiggler, undulator, and laser projection in the electron beam storage ring. So to speak, while it is a combine method,
The present invention is characterized by a complete function separation (separate function) method in which independent devices for acceleration, bunching, and generation of synchrotron radiation are connected to each other without requiring a storage ring. However, it goes without saying that the present invention can also be applied to accelerators and storage rings.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The drawings are conceptual layout diagrams of a compact cyclobunching coherent radiation generator for carrying out the present invention, in which an acceleration energy of 0.5 (MeV) (MeV: MeV: (Electron beam generator) 2, acceleration electron beam 3, turning energy adjusting magnet 4, solenoid coil 5, cyclotron resonance high frequency cavity 6, beam direction adjusting magnet 7, transition radiation light generation thin film 8, coherent radiation light 9 , Electron collector 1
0, a high voltage generator 11, and a bias adjustment resistor 12 are included.

Then, the electron beam 3 emitted from the electron beam generator 2 is introduced into the magnetic field of the solenoid coil 5 obliquely to the coil axis through the turning energy adjusting magnet 4, and the turning kinetic energy (γ ₁ -1 ) Pass through the high-frequency cavity 6 while drawing a spiral locus with m ₀ c ² . Where γ
₁ is a relativistic energy factor of turning, and γ ₁ m ₀ c ² is turning kinetic energy and rest mass energy m ₀ c ² = 0.
It is the sum of 511 MeV. m ₀ is the electronic mass, and c is the speed of light.

As long as the stability of the electric field frequency in the cavity is normal, the electrons flying in the high-frequency cavity 6 having the axial length L at the coil axial velocity β ₁₁ c will be in the time t = L / β ₁₁ c. Continues the swirling motion that resonates with the high-frequency electric field. Resonance frequency (ω
_rf / 2π) is due to the relativistic Doppler effect

[Equation 1] ω _c ^* ≡eB ₀ / m ₀ , γ ₁₁ ≡ (1-β ₁₁ ² )
It becomes ^-1/2 . (Ω _c ^* / 2π) is the cyclotron frequency in the particle stationary system, and B ₀ is the solenoid magnetic flux density. Further, β _rf c is a propagation velocity in the axial direction of the solenoid magnetic field of the high frequency electric field, and is positive when β ₁₁ is in the same direction as β ₁₁ . Practically, this high frequency does not have to be a traveling wave, and may be a standing wave. During the flight at time t, due to the relativistic effect of the turning motion that is the generation mechanism of the cyclotron maser,
The swirl phase of the electrons converges on the electric field phase, and the swirl phase width is compressed to 360 ° / a. Where a is a coefficient called bunching coefficient

[Equation 2] Can be given. Therefore, the electron beam is spatially bunched, and after passing through the bunch system composed of the solenoid coil 5 and the high frequency cavity 6,

[Equation 3] Is bunched in length. Where βc is an electron velocity corresponding to an acceleration energy of 0.5 MeV, that is, γ = 2, and β≡
(1-γ ⁻² ) ^1/2 = 0.87. If the turning energy is 0.30 MeV, that is, γ ₁ = 1.6, then γ ₁₁ = 1.4 and β ₁₁ = 0.70. Furthermore, L = 2.0 (m), ω _c ^{* /} 2π = 3.17 (GH
_z ), (GH _z : gigahertz) (2)
From the formula, a = 340, and from the formula (3), l = 190 (μ
It is estimated that the electrons are bunched in the length of m).
Experience shows that

[Equation 4] High-intensity coherent radiation is obtained in the wavelength region λ in the range. In this embodiment, λ

The number N in one pulse of the bunching electron population is the acceleration current I (A)

[Equation 5] Given in. e is an electronic charge. When I = 1 (A), in this embodiment,

Since the normal radiant light intensity is proportional to the electron current I, it is also proportional to N. A strong coherent radiant light with N = 4.5 × 10 ⁹ times the coherent radiant light intensity is generated. The multiplication factor N has a low electron energy of 0.5 M in this embodiment.
There is still more than the weakness of the incoherent synchrotron radiation intensity at eV.

In the present invention, the load of the high voltage generator 11 is, as can be understood from the figure, be the difference (II) between the current I drawn from the electron source 1 and the collector current I ′ flowing into the collector 10. Has become. From experience, (I-I ') can be suppressed to about ^10-4 times I, so that a high voltage generator having a very small current capacity is sufficient in the present invention.
Further, since the bunching electrons can be accelerated by slightly changing the resonance condition of the equation (1), it is theoretically possible to set I-I '= 0 or I-I'<0.

The electron flow path in the present invention is the electron source 1.
From coherent synchrotron radiation emitted from the collector 1
It reaches 0, and then returns to the electron source 1 again through the external connection. This return is essentially different from the return of electrons in a conventional synchrotron radiation photoelectron storage ring. In the electron storage ring, an ultra-high vacuum is indispensable, and besides, there are problems such as deterioration of electron beam quality due to generation of synchrotron radiation and efficiency of a reflection mirror for generating a free electron laser. Do not worry about the point at all.

In the present invention, as is clear from both equations (3) and (4), the wavelength λ of the coherent radiation becomes shorter in inverse proportion to the square of the cyclotron resonance frequency (ω _c ^* / 2π). Therefore, if the resonance frequency is increased by one digit from that of the present embodiment to be 50 (GH _z ), Visible light is generated. Furthermore, if the cyclotron resonance frequency (ω ₀ ^* / 2π) is increased up to the frequency 150 (GH _z ) obtained with a commercially available gyrotron oscillator, the wavelength is 2
It is also possible to generate a 0 (nm) coherent X-ray, that is, a straw X-ray laser. As is clear from the equation (3), the swirling energy (γ ₁ −
The wavelength can be significantly changed by adjusting 1).

The present invention is particularly effective in increasing the brightness of transition radiation. In order to generate synchrotron radiation for the purpose of improving coherency and monochromaticity of transition radiated light, it is particularly effective to use a laminated thin film having a multiple combination structure of metals or thin films having different refractive indexes.

[00014]

As described above, the present invention does not require an accelerator and an electron beam storage ring, which are indispensable in conventional synchrotron radiation facilities and free electron laser facilities, and is simple in the scale of a medium- or large-sized electron microscope. It is possible to generate photoluminance coherent radiation from the millimeter wave to the X-ray region with various devices and extremely simple operation. The effect of resource saving, energy saving or labor saving on the equipment, operating cost and operating system according to the present invention is immeasurable, and will greatly change the trend of synchrotron radiation science and technology in the world.

[Brief description of drawings]

FIG. 1 is a conceptual layout diagram of a compact cyclobunching coherent radiation generation device as an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electron source 2 Electron beam generator 3 Acceleration electron beam 4 Rotation energy adjustment magnet 5 Solesoid coil 6 Cyclotron resonance high frequency cavity 7 Beam direction adjustment magnet 8 Thin film for generation of transition radiation 9 Coherent radiation 10 Electron collector 11 High voltage generator 12 Bias adjustment resistor

Claims (2)

[Claims] 1. An accelerated electron beam is obliquely introduced to the axis of a solenoid magnetic field, and a cyclotron resonance high-frequency cavity mounted in the magnetic field causes resonance in the cyclotron rotation of electrons to induce rotation phase bunching. Then, bunching electrons are extracted as an ultra-short pulse beam outside the solenoid magnetic field, and are passed through a synchrotron radiation generating wiggler or undulator or a transition radiation generating thin film to generate cyclobunching coherent radiation. 2. An accelerated electron beam is obliquely introduced to the axis of a solenoid magnetic field, and a cyclotron resonance high-frequency cavity mounted in the magnetic field causes resonance in electron cyclotron rotation to induce rotation phase bunching. Then, a device for extracting bunching electrons as an ultrashort pulse beam outside the magnetic field of the solenoid and passing it through a synchrotron radiation generating wiggler or undulator or a transition radiation generating thin film to generate cyclobunching coherent radiation.