A full-optical Compton scattering device with an even-order aspheric reflector

Abstract

An all-optical Compton scattering device containing an even-order aspheric reflector includes an ultra-intense incident laser, a gas target, and an even-order aspheric reflector. A beam of ultra-intense laser is incident on the surface of the even-order aspheric reflector, and after being reflected by the mirror, it converges on the z-axis and reacts with the gas target to generate an ultrafast electron beam without phase loss. During the propagation process, the electron beam generates self-synchronous continuous Compton scattering with the focused strong laser. The present invention integrates electron acceleration and radiation generation into one, and utilizes the converging effect of the even-order aspheric reflector on the laser to greatly improve the energy of the electron beam and its collision efficiency with the laser, so that the radiation is enhanced and the damage of the reflected laser to the optical element is avoided. The present invention is a beam focusing device suitable for laser tailfield electron acceleration, and relates to the field of laser tailfield electron acceleration and the generation of its radiation source, and in particular to the field of all-optical Compton scattering based on the laser tailfield.

Description

Technical Field

[0001] The invention discloses a beam focusing device suitable for laser tailfield electron acceleration, and relates to the field of laser tailfield electron acceleration and the generation of its radiation source, and in particular to the field of all-optical Compton scattering based on laser tailfield. Background Art

[0002] Ultra-intense ultra-short lasers are the brightest light sources known so far. Their rapid development has created unprecedented extreme physical conditions for mankind, allowing the interaction between light and matter to enter the realm of relativity. The new laser wakefield electron accelerator driven by femtosecond ultra-intense lasers has a huge acceleration gradient, which can accelerate electrons to the GeV level on a small scale, greatly reducing the scale and cost of the accelerator, and has great scientific significance for research in related fields of new radiation sources. Among them, gamma-ray sources have very important application value in nuclear astrophysics, quantum physics, medical imaging and diagnosis, and inverse Compton scattering based on the collision of relativistic electron beams and lasers is currently the most effective way to produce high-energy gamma rays.

[0003] Existing electron acceleration and radiation generation schemes lack effective laser focusing, and have problems such as laser loss and dephasing that prevent the electron energy from being further increased. The electron beam cannot collide accurately with the laser beam, and the collision efficiency is low, which limits the energy, brightness and yield of gamma rays. In addition, ultra-strong lasers are easily damaged by vertical reflection from plane mirrors, affecting subsequent experiments.

[0004] The quality of the gamma-ray source generated by the existing all-optical gamma-ray radiation source scheme cannot meet the current application requirements, so there is an urgent need to study an improved all-optical Compton scattering device. On the one hand, it can achieve effective focusing of the laser, increase the energy of the electron beam to produce high-energy gamma rays, and at the same time achieve precise collision of laser and electrons, and enhance the brightness of gamma rays to meet application requirements; on the other hand, it can prevent the reflected laser from damaging other optical devices after being reflected by the plane mirror. Summary of the invention

[0005] The purpose of the present invention is to address the shortcomings of the above-mentioned existing all-optical Compton scattering scheme, integrate electron acceleration and radiation generation into one, and effectively focus the laser by designing a reflector with a specific surface shape, accelerate the laser tail field electrons without phase loss, push the electrons to high energy, realize the continuous collision of laser and electron beam in self-synchronization, and improve the energy and brightness of the radiation source; and the return light is very weak and will not cause damage to the components at the front end of the laser.

[0006] The technical solution of the present invention is as follows:

[0007] A full-light Compton scattering device containing an even-order aspheric reflector is characterized in that it comprises: an ultra-strong incident laser, an even-order aspheric reflector, a gas target and a vacuum chamber; the gas target and the even-order aspheric reflector are sequentially placed in the incident direction of the ultra-strong incident laser, and the gas target and the even-order aspheric reflector are both placed in the vacuum chamber;

[0008] The focal spot center of the ultra-strong incident laser, the gas target center and the center of the even-order aspheric reflector are coaxial;

[0009] The radius of the even-order aspheric reflector is equal to the radius of the incident laser; the center of the even-order aspheric reflector is provided with a small hole, the radius of which is approximately one tenth of the diameter of the even-order aspheric reflector, thereby avoiding the loss of excessive super-strong incident laser light and ensuring that electrons and radiation can pass through the small hole and continue to propagate along the optical axis, thereby facilitating subsequent analysis of the radiation.

[0010] The gas target action point is located at the shortest focal length on the optical axis, and the gas length is roughly equal to the focal depth of the even-order aspheric reflector.

[0011] Optionally, the even-order aspheric reflector has a diameter of 200 mm and a radius of a central hole thereof of 30 mm.

[0012] Optionally, the ultra-strong incident laser spot diameter is 200 mm, the incident energy is 30 J, and the pulse width is 30 fs.

[0013] Optionally, the even-order aspheric reflector has only 2, 4, and 6 order coefficients with values, and the other order coefficients are all zero, and the 2, 4, and 6 order coefficients are respectively: -2.5×10 -4 , 1.25×10 -8 , -8.344×10 -13 .

[0014] Optionally, the gas target is produced by a supersonic gas nozzle, the gas is He gas, and the initial pressure is 3×10 5 Pa, the valve diameter is 1mm, the distance between the action point and the supersonic gas nozzle opening is 5mm, and a 10mm length and a density of 10 19 cm -3 of gas for electron acceleration in the laser tail field.

[0015] Compared with the prior art, the present invention has the following significant features:

[0016] 1. It achieves a long focal depth, effectively solves the phase loss problem in accelerating electrons, and can push electrons to high energy to generate high-energy gamma-ray radiation;

[0017] 2. It can realize self-synchronization with micron spatial precision and femtosecond time precision, and achieve precise collision;

[0018] 3. The lasers that collide with the electrons are all focused lasers, which significantly improves the collision efficiency between electrons and lasers and further increases the brightness of the radiation source;

[0019] 4. The reflected laser converges on the z-axis at a certain angle and diverges quickly to avoid the return light damaging the components at the front end of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the optical path of the present invention. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with embodiments and drawings, but the protection scope of the present invention shall not be limited thereto.

[0022] Please read first Figure 1 , Figure 1 This is a schematic diagram of the optical path of a full-light Compton scattering device containing an even-order aspheric reflector of the present invention. As can be seen from the figure, the specific optical path is:

[0023] A beam of ultra-strong incident laser light 1 with a radius of R is horizontally incident on the surface of an even-order aspheric reflector 2 located in a vacuum chamber along the positive direction of the z-axis. The reflected laser light 5 converges at different positions of the z-axis at different times. The reflected laser light 5 and the gas target 3 work together to generate an accelerated electron beam 6, which moves along the z-axis. Due to the different focal lengths of the reflected laser light, the accelerated electron beam 6 moves along the positive direction of the z-axis at a superluminal speed v. z Therefore, the accelerated electron beam 6 and the focused strong laser converged in its propagation direction produce self-synchronous continuous Compton scattering; the generated radiation continues to propagate along the z axis through the small hole in the center of the even-order aspheric reflector 2, and finally emits out of the vacuum cavity.

[0024] Combination Figure 1 The specific steps of the present invention are as follows:

[0025] 1) An ultra-strong ultrashort laser with an energy of 30 J, a pulse width of 30 fs, and a spot diameter of 200 mm is selected as the ultra-strong incident laser 1, and an even-order aspheric reflector with a diameter of 200 mm is selected as the even-order aspheric reflector 2. The even-order 2, 4, and 6 coefficients are: -2.5×10 -4 , 1.25×10 -8 , -8.344×10 -13 The radius of the central hole is 30 mm; the gas target 3 is produced by a supersonic gas nozzle, the gas is He gas, and the initial pressure is 3×10 5 Pa, the valve diameter is 1mm, the distance between the action point and the supersonic gas nozzle opening is 5mm, and a 10mm length and a density of 10 19 cm -3of gas for electron acceleration in the laser tail field;

[0026] 2) constructing an optical path so that the focal spot center of the ultra-strong incident laser 1, the center of the even-order aspheric reflector 2 and the center of the gas target 3 are coaxial;

[0027] 3) placing the gas target 3 at the shortest focal length on the optical axis; controlling the jet and laser emission time to ensure that the reflected laser 5 and the gas target 3 fully interact to generate an accelerated electron beam 6;

[0028] 4) The accelerated electron beam 6 and the laser light converged on the z-axis undergo Compton scattering, and the generated radiation passes through the small hole of the even-order aspheric reflector 2 and continues to propagate forward;

[0029] 5) In the embodiment of the present invention, since a high-power laser beam is used, in order to avoid the adverse effects of air on the experiment, the chamber 4 where the even-order aspheric reflector 2 and the gas target 3 are located needs to be evacuated during target shooting.

Claims

1. A full-optical Compton scattering device containing an even-order aspheric reflector, characterized in that: include: An ultra-intense incident laser (1), an even-order aspheric reflector (2), a gas target (3) and a vacuum chamber (4); the gas target (3) and the even-order aspheric reflector (2) are sequentially placed in the incident direction of the ultra-intense incident laser (1), and the even-order aspheric reflector (2) and the gas target (3) are both placed in the vacuum chamber (4); The focal spot center of the super-intense incident laser (1), the center of the gas target (3) and the center of the even-order aspheric reflector (2) are coaxial; The radius of the even-order aspheric reflector (2) is equal to the radius of the super-strong incident laser (1); the center of the even-order aspheric reflector (2) is provided with a small hole, and the radius of the small hole is one tenth of the diameter of the even-order aspheric reflector (2); The action point of the gas target (3) is located at the shortest focal length on the optical axis, and the gas length is equal to the focal depth of the even-order aspheric reflector (2).

2. A full-optical Compton scattering device containing an even-order aspheric reflector according to claim 1, characterized in that: The even-order aspheric reflector (2) has a diameter of 200 mm and a radius of a central aperture of 30 mm.

3. The all-optical Compton scattering device comprising an even-order aspheric reflector according to claim 1, characterized in that: The ultra-strong incident laser (1) has a spot diameter of 200 mm, an incident energy of 30 J, and a pulse width of 30 fs.

4. The all-optical Compton scattering device comprising an even-order aspheric reflector according to claim 1, characterized in that: The even-order aspheric reflector (2) has only 2, 4, and 6 order coefficients with values, and the other order coefficients are all zero. The 2, 4, and 6 order coefficients are respectively: -2.5×10 -4 , 1.25×10 -8 , -8.344×10 -13 .

5. The all-optical Compton scattering device comprising an even-order aspheric reflector according to claim 1, characterized in that: The gas target (3) is produced by a supersonic gas nozzle. The gas is He gas with an initial pressure of 3×10 5 Pa, the valve diameter is 1mm, the distance between the action point and the supersonic gas nozzle opening is 5mm, and a 10mm length and a density of 10 19 cm -3 of gas for electron acceleration in the laser tail field.

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