阅读说明：本技术 基于激光加速器的中微子束产生装置 (Neutron beam generating device based on laser accelerator ) 是由 李儒新 张辉 李顺 于 2020-04-13 设计创作，主要内容包括：一种基于激光加速器的中微子束产生装置,包括激光器、反射镜、离轴抛物面镜、加速靶、转化靶、电动平移台和真空室。本发明首先利用激光聚焦系统对激光脉冲进行聚焦提高激光光强,然后将聚焦后的强激光与加速靶相互作用获得质子束,最后利用质子束与转化靶相互作用产生中微子束。本发明具有小型化、变向灵活、能量可控、成本低等特点。(A neutron beam generation device based on a laser accelerator comprises a laser, a reflector, an off-axis parabolic mirror, an acceleration target, a conversion target, an electric translation table and a vacuum chamber. The invention firstly utilizes a laser focusing system to focus laser pulses to improve the laser intensity, then the focused strong laser interacts with an accelerating target to obtain a proton beam, and finally the proton beam interacts with a conversion target to generate a neutron beam. The invention has the characteristics of miniaturization, flexible direction change, controllable energy, low cost and the like.)

1. A neutron beam generation device based on a laser accelerator is characterized by comprising a laser (1), a reflector (2), an off-axis parabolic mirror (3), an acceleration target (4), a conversion target (5), an electric translation table (6) and a vacuum chamber (7): the laser device comprises a reflector (2), an off-axis parabolic mirror (3), an accelerating target (4) and a converting target (5) which are sequentially arranged along the direction of a laser pulse (101) output by the laser device (1), wherein the off-axis parabolic mirror (3), the accelerating target (4) and the converting target (5) are arranged on an electric translation table (6), the accelerating target (4) is positioned on the focal plane of the off-axis parabolic mirror (3), the reflector (2), the off-axis parabolic mirror (3), the accelerating target (4), the converting target (5) and the electric translation table (6) are arranged in a vacuum chamber (7), and an accelerated proton beam (401) is output by utilizing the interaction of the focused laser pulse (101) and the accelerating target (4); and generating a neutron beam (501) by utilizing the interaction of the proton beam (401) and the conversion target (5).

2. The neutron beam generating device according to claim 1, wherein the change of the transmission direction of the laser pulse (101) is realized by adjusting the angle of the mirror (2), and the angle adjustment of the mirror (2) is electrically adjusted.

3. The neutron beam generating device according to claim 1, wherein the pulse width of the laser pulse (101) is in the range of 15 femtoseconds to 500 femtoseconds, and the light intensity after focusing is in the range of 10 femtoseconds¹⁸W/cm²-10²³W/cm²。

4. The neutron beam generating apparatus according to claim 1, wherein the accelerating target (4) is a solid film or a gas rich in hydrogen element for generating and accelerating a proton beam.

5. The neutron beam generating device according to claim 4, wherein the thickness of the solid thin film is in the range of 1 nm to 10000 nm.

6. The neutron beam generating device of claim 4, wherein the density of the gas is greater than the critical density n_cr＝1×10²¹/cm³。

7. The neutron beam generating apparatus according to claim 1, wherein the energy of the proton beam (401) is in the range of 0.3GeV to 100 GeV.

8. The neutron beam generating device according to claim 1, wherein the conversion target (5) is a solid column made of carbon, beryllium, aluminum, copper, gold, silver or lead.

Technical Field

The invention relates to the technical field of ion acceleration and the field of nuclear physics, in particular to a laser accelerator-based neutron beam generation device.

Background

The interaction between the neutrino and the substance is small, the energy lost when the neutrino passes through the substance is small, and the neutrino can penetrate the earth, so that the neutrino can be used for the neutrino communication, and the arbitrary connection between two points of the earth is realized. The neutron communication can break through two forbidden zones which cannot be broken through by the underwater electromagnetic wave communication and the underground electromagnetic wave communication, global communication is achieved, and the neutron communication has wide application prospect in the aspects of national safety and civil requirements because the neutron communication is not easy to intercept, almost has no attenuation, and is not afraid of external interference. The premise of wide application of the mesoparticle is that a mesoparticle source with controllable energy and high flux can be obtained, and the mesoparticle source generated by cosmic rays has extremely high energy and limited flux and is difficult to capture and apply. Currently, the main method for obtaining neutron beam source is to utilize the interaction between energetic protons and matter, the collision between protons and nuclei to generate pi mesons, and the decay of pi mesons to generate neutrino (see Sacha e.kopp, Accelerator neutron beams. physics Reports,2007.439(3): p.101-159.). This method has high quality requirements for proton beams, and conventional mass production of such high-energy proton beams is performed using a conventional radio frequency accelerator. However, the conventional ion accelerator has low acceleration gradient, high construction cost, large volume and high operation and maintenance cost. The cost of heavy ion accelerators in Lanzhou neighborhood of China is more than hundreds of millions of RMB, and the cost of large ion accelerators such as German GSI which are put into operation at present is more than 10 hundred million Euros. Meanwhile, in practical application of the neutron beam communication, the transmission direction of the neutron beam needs to be changed in real time according to the target position of the received signal, which cannot be realized on the traditional accelerator, because the traditional accelerator controls the transmission of the proton beam by using a magnet, the direction and the position of the proton beam are difficult to change. In addition, for a conventional accelerator which is already built, the proton energy is single energy and can not be changed basically, so that the energy of the corresponding neutrino generated is also fixed, and the requirement of some applications which need different energies can not be met. In summary, the conventional rf accelerator driven neutron beam source has a great limitation in practical application.

In recent years, with the development of Chirped Pulse Amplification (CPA), the laser can generate ultra-short strong laser pulses in the femtosecond order, the laser power can reach 10PW, and the laser intensity can reach or even exceed 10PW²²W/cm²Accelerating protons by interaction of ultrashort intense laser pulses with substances (gases, solids and clusters) is a major concern (see Zhen Guo, et al, Improvement of the following dimensional transformation for mirrors 10-PW Ti: sapphire pulsed amplification laser system, 2018.26(20): p.26776-26786). Compared with the traditional accelerator, the acceleration gradient of the proton accelerator based on the interaction of the strong laser and the plasma can be improved by 4-5 orders of magnitude, the desktop and miniaturization of the accelerating device are expected to be realized, and the accelerator is greatly reducedThe construction cost. The beam quality of the proton source can be accelerated compared with the traditional method, and the proton source can be used for further generating novel particle beams such as neutrino and the like.

Disclosure of Invention

The invention mainly aims to overcome the defects of the prior art and provides a neutron beam generating device based on a laser accelerator. The invention has the characteristics of miniaturization, flexible direction change, controllable energy, low cost and the like.

The technical solution of the invention is as follows:

a neutron beam generating device based on a laser accelerator is characterized by comprising a laser, a reflector, an off-axis parabolic mirror, an accelerating target, a converting target, an electric translation table and a vacuum chamber: the reflector, the off-axis parabolic mirror, the accelerating target and the converting target are arranged on the electric translation stage in sequence along the laser pulse direction output by the laser, the accelerating target is positioned on the focal plane of the off-axis parabolic mirror, the reflector, the off-axis parabolic mirror, the accelerating target, the converting target and the electric translation stage are arranged in the vacuum chamber, and the accelerated proton beam is output by utilizing the interaction of the focused laser pulse and the accelerating target; and generating a neutron beam by utilizing the interaction of the proton beam and the conversion target.

The change of the transmission direction of the laser pulse is realized by adjusting the angle of the reflector, and the angle adjustment of the reflector is electric adjustment.

The pulse width range of the laser pulse is 15-500 femtoseconds, and the light intensity range after focusing is 10¹⁸W/cm²-10²³W/cm²。

The accelerating target is a solid film or gas rich in hydrogen elements and is used for generating and accelerating proton beams.

The thickness of the solid film ranges from 1 nanometer to 10000 nanometers.

The density of the gas is greater than the critical density n_cr＝1×10²¹/cm³。

The energy range of the proton beam is 0.3GeV-100 GeV.

The conversion target is a solid column made of carbon, beryllium, aluminum, copper, gold, silver or lead.

The invention has the following advantages:

1. and (3) miniaturization: the laser accelerated proton only relates to the laser, the reflector, the off-axis paraboloidal mirror, the accelerating target and other parts, compared with the traditional radio frequency accelerator, the invention has the advantages of great simplification and realization of miniaturization of the device.

2. Flexible direction change: the direction of generating the proton beam is controlled by adjusting the transmission direction of the laser pulse, the emission direction of the neutron beam is finally controlled, the flexible direction change of the neutron beam is realized by an optical method, and the invention is beneficial to the fields of neutron beam communication and the like.

3. The energy is controllable: by changing the parameters (energy, pulse width and light intensity) of the laser pulse and the parameters of the accelerating target, the energy of the accelerated proton beam can be controlled in real time, the energy of the generated neutron beam can be finally controlled, and the application requirements of the neutron beam communication under different environments can be met.

4. The cost is low: the acceleration gradient of the laser accelerated proton is 4-5 orders of magnitude of the traditional accelerator, the proton beam can obtain large energy in a short distance, the neutron beam can be generated in a mesa scale system, and the construction cost and the maintenance cost can be greatly reduced.

Drawings

Fig. 1 is a schematic structural diagram of a neutron generating device based on a laser accelerator according to the present invention.

Detailed Description

In order to make the aforementioned advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It should be noted that the present invention should not be limited to the details of the following embodiments, and those skilled in the art should understand the present invention from the spirit embodied in the following embodiments, and each technical term can be understood in the broadest sense based on the spirit of the present invention.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a neutron generating device based on a laser accelerator according to the present invention. It can be seen from the figure that the invention relates to a laser accelerator-based neutron beam generating device, which comprises a laser 1, a reflector 2, an off-axis parabolic mirror 3, an accelerating target 4, a converting target 5, an electric translation table 6 and a vacuum chamber 7: the laser device comprises a reflector 2, an off-axis parabolic mirror 3, an accelerating target 4 and a converting target 5 which are sequentially arranged along the direction of a laser pulse 101 output by the laser device 1, wherein the off-axis parabolic mirror 3, the accelerating target 4 and the converting target 5 are arranged on an electric translation stage 6, the accelerating target 4 is positioned on the focal plane of the off-axis parabolic mirror 3, the reflector 2, the off-axis parabolic mirror 3, the accelerating target 4, the converting target 5 and the electric translation stage 6 are arranged in a vacuum chamber 7, and an accelerated proton beam 401 is output by the interaction of the accelerating target 4 of the focused laser pulse 101; the proton beam 401 is used to interact with the conversion target 5 to generate a neutron beam 501.

The change of the transmission direction of the laser pulse 101 is realized by adjusting the angle of the mirror 2, and the angle adjustment of the mirror 2 is electrically adjusted.

The pulse width range of the laser pulse 101 is 15 femtoseconds-500 femtoseconds, and the light intensity range after focusing is 10¹⁸W/cm²-10²³W/cm²。

The acceleration target 4 is a solid film or gas rich in hydrogen element, and is used for generating and accelerating a proton beam.

The thickness of the solid film ranges from 1 nanometer to 10000 nanometers.

The density of the gas is greater than the critical density n_cr＝1×10²¹/cm³。

The energy range of the proton beam 401 is 0.3GeV-100 GeV.

The conversion target 5 is a solid column made of carbon, beryllium, aluminum, copper, gold, silver or lead.

The parameters of the examples are as follows:

the parameters of the laser 1 are: the center wavelength was 800 nm, the full width at half maximum of the spectrum was 90 nm, the pulse width was 30 femtoseconds, the maximum energy of the laser was 300 joules, and the beam diameter was 500 mm. The vacuum chamber 7 is in a vacuum state. According to neutron beam outflowThe transmission direction of the laser pulse 101 is changed by the angle of the electric adjusting reflector 2 according to the emission direction requirement, the position of the electric translation table 6 is adjusted accordingly, the direction of the laser pulse incident to the off-axis parabolic mirror 3 is guaranteed to be unchanged, the electric device is powered off and locked after adjustment is completed, the position of a device is guaranteed to be unchanged, and the emission direction adjustment of the neutron beam is completed. The laser pulse 101 is reflected by the mirror 2 and focused by the off-axis parabolic mirror 3. The focal length of the off-axis parabolic mirror 3 is 1000 mm, the full width at half maximum of the diameter of a laser focusing focal spot is 5 microns, the energy concentration ratio is 35%, and the laser light intensity at the focal point is 1.8 multiplied by 10²²W/cm²The corresponding normalized rise magnitude is 64. The focus of the off-axis parabolic mirror 3 is on the front surface of the accelerating target 4, the incidence direction is the normal direction of the target surface, the accelerating target 4 is a high-density hydrogen-containing solid film target with the thickness of 54 nanometers and the density of 300n_cr. Under the action of laser light pressure, the accelerating target 4 is continuously accelerated as a whole, under the condition of acceleration, the laser energy is effectively transferred to hydrogen ions, the emergent direction of a high-energy proton beam 401 generated by acceleration is the laser transmission direction, the energy is more than 0.8GeV, and the quantity is 1 multiplied by 10¹¹And (4) respectively. The conversion target 5 is a carbon target, placed behind the acceleration target 4, and has dimensions of 5 cm × 100 cm with the long side parallel to the laser transmission direction. The high-energy proton beam 401 generated by laser acceleration bombards the conversion target 5, collides with the nucleus to generate pi meson, then the pi meson decays to generate the neutron beam 501, and the average energy of the finally obtained neutrino is 0.035GeV, the number is 1 × 10¹⁰And (4) respectively.

In the present embodiment, the generation frequency of the neutron beam 501 is determined by the frequency of the laser 1, and the beam intensity of the neutron beam can be controlled by changing the frequency of the laser.

Experiments show that the invention has the characteristics of miniaturization, flexible direction change, controllable energy, low cost and the like, and can be applied to the fields of meson-micro communication and the like.