Ion beam generation system based on interaction of laser and conical target

Abstract

The utility model belongs to the technical field of particle acceleration, and relates to an ion beam generation system based on interaction of laser and a conical target, which comprises a laser source, a vacuum target chamber, a transmission focusing device, a modulation solid target and a light beam separation module, the laser source is arranged outside the vacuum target chamber and serves as an input end, the light beam separation module is arranged outside the vacuum target chamber and serves as an output end, and the transmission focusing device and the modulation solid target are both arranged inside the vacuum target chamber; the modulation solid target comprises a plane target, the plane, facing the input end, of the plane target serves as the front surface, and a pre-plasma and / or a conical target are / is arranged on the front surface of the plane target; the laser source generates laser, and the laser enters the vacuum target chamber and then enters the modulation solid target after passing through the transmission focusing device, so that the laser and the modulation solid target interact and then are emitted out of the vacuum target chamber, and ion beams with electrons and protons separated are generated through the light beam separation module. According to the invention, the ion beam with high energy and high conversion efficiency can be generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of particle acceleration, in particular to an ion beam generation system based on interaction of laser and cone target. BACKGROUND

[0002] Interaction of laser and matter is one of the core problems in physics that has always attracted much attention. With the development of laser technology, high laser intensity of 10 21 -10 23 W / cm 2 can be generated in the current laboratory, which can directly ionize matter into plasma. The new type of particle accelerator based on ultrastrong laser plasma interaction has an acceleration gradient higher than that of traditional particle accelerators by more than three orders of magnitude, and the generated electron pulse has the characteristics of ultra-short, ultra-bright, collimation and high conversion efficiency, which has great significance in ion-driven inertial confinement fusion, beam target neutron source, warm-dense matter heating, tumor treatment and particle beam equipment, satellite anti-missile and other applications. Therefore, in recent years, it has attracted extensive attention of researchers at home and abroad. Among them, high-energy high-conversion efficiency ion beams obtained by laser plasma interaction have important value in secondary particle generation, free electron lasers, ion acceleration and other fields.

[0003] In recent years, people have proposed various ion acceleration mechanisms, including: target normal sheath acceleration (TNSA), laser radiation pressure acceleration (RPA), target breakout afterburner acceleration (BOA), electrostatic shock wave acceleration, double-peak electric field acceleration, etc. Among them, the TNSA acceleration mechanism has the advantages of simple scheme design and easy implementation in experiments, and is the most widely used ion acceleration scheme in experiments at present.

[0004] However, the final energy conversion efficiency of laser to high-energy ions through the TNSA acceleration mechanism is only 5%-12%, and the highest proton energy reported by the current experiment through the TNSA mechanism is only 85MeV, which limits its application in some fields. Therefore, how to improve the energy conversion efficiency from laser to electron and from electron to ion and improve the maximum proton energy is a key scientific problem to be solved in the TNSA mechanism. CONTENT OF THE UTILITY MODEL

[0005] Therefore, it is necessary to provide an ion beam generation system based on interaction of laser and cone target to improve the energy conversion efficiency and the maximum cut-off energy of protons, and generate high-energy high-conversion efficiency ion beams in view of the above technical problems.

[0006] An ion beam generation system based on laser and cone target interaction, comprising:

[0007] a laser source, a vacuum target chamber, a transmission focusing device, a modulation solid target and a beam separation module;

[0008] The laser source is arranged outside the vacuum target chamber as an input end, the beam separation module is arranged outside the vacuum target chamber as an output end, and the transmission focusing device and the modulation solid target are both arranged inside the vacuum target chamber;

[0009] The modulation solid target comprises a plane target, a front surface of the plane target being a plane facing the input end, and a pre-plasma and / or a cone target being arranged on the front surface of the plane target;

[0010] The laser source generates laser light, which is injected into the vacuum target chamber, passes through the transmission focusing device, is injected into the modulation solid target, and is emitted from the vacuum target chamber after interacting with the modulation solid target, so as to generate an ion beam with electron and proton separation through the beam separation module.

[0011] In an embodiment, the transmission focusing device comprises an optical transmission module and a laser focusing module;

[0012] The optical transmission module is arranged on the light path of the laser light and changes the direction of the laser light before injecting it into the laser focusing module;

[0013] The laser focusing module receives the emitted laser light from the optical transmission module and focuses it before injecting it into the modulation solid target.

[0014] In an embodiment, the vacuum target chamber has an input window and an output window, the laser light is injected into the vacuum target chamber through the input window and is emitted from the vacuum target chamber through the output window;

[0015] The beam separation module is two deflection magnets, which are respectively arranged on both sides of the output window and are both parallel to the emission direction of the ion beam.

[0016] In an embodiment, the cone target comprises a body and a target groove;

[0017] The body is a cylindrical structure, a front surface of the body being a plane facing the input end, and the target groove being recessed towards the output end on the front surface of the body;

[0018] The target groove is a conical structure, and the bottom surface of the target groove is coplanar with the front surface of the body.

[0019] In an embodiment, the angle between the axis of the conical structure and any generatrix is 45°.

[0020] In one embodiment, when the pre-plasma is arranged on the front surface of the planar target, the pre-plasma is a planar plate structure, one surface of which is in abutment with the front surface of the planar target, and the other surface is directed towards the direction of the laser source.

[0021] In one embodiment, when the pre-plasma and the conical target are arranged on the front surface of the planar target, the pre-plasma comprises a first part and a second part; the first part is a planar plate structure and is connected with the second part; the second part is a conical structure, and the side surface of the second part is in abutment with the conical target.

[0022] In one embodiment, the planar target is a carbon-hydrogen target.

[0023] In one embodiment, the laser source generates a linearly polarized femtosecond Gaussian laser.

[0024] In one embodiment, the intensity of the femtosecond Gaussian laser is 10 20 ~10 22 W / cm 2 .

[0025] The above ion beam generation system based on the interaction between the laser and the conical target designs a modulation solid target with a composite plasma structure. Specifically, on the basis of a carbon-hydrogen planar target, a pre-plasma and a conical target are arranged on the front surface of the planar target as a superhot electron source. The superhot electron source can provide additional superhot electrons for ion acceleration after laser incidence and can also assist the laser in self-focusing. Through the interaction between the linearly polarized Gaussian laser and the modulation solid target, a high-energy ion beam energy spectrum with much higher energy conversion efficiency and cut-off energy than the planar solid target can be generated under the existing laser technology conditions. The high-conversion-efficiency electron beam can generate a stronger sheath electric field in the target back vacuum area, thereby effectively driving ion acceleration. Moreover, the ion beam with high enough energy has important application value in driving inertial confinement nuclear fusion, beam-target neutron source, and warm-dense matter heating research. In addition, the generated ion beam energy spectrum can be effectively adjusted by changing the laser intensity, the structure and density of the pre-plasma or the solid target. Increasing the laser intensity can further improve the cut-off energy of the ion beam. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 FIG. 1 is a structural schematic diagram of an ion beam generation system based on the interaction between the laser and the conical target in one embodiment;

[0027] Figure 2 FIG. 4 is a proton energy spectrum diagram finally obtained by the ion beam generation system based on the interaction between the laser and the conical target in one embodiment;

[0028] Figure 3Figure of the proton energy conversion efficiency for the ion beam generation system based on the interaction of laser and cone target in one embodiment.

[0029] Reference signs:

[0030] Laser source 1, optical transmission module 2, laser focusing module 3, pre-plasma 4, beam separation module 5, vacuum target chamber 6, cone target 7, planar target 8, injector 9. DETAILED DESCRIPTION

[0031] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not intended to limit the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of the present application.

[0032] It should be noted that all directional indications, such as up, down, left, right, front, back, etc., in the embodiments of the present application are only used to explain the relative positional relationship, movement condition, etc. between components in a certain posture (as shown in the drawings), and if the certain posture changes, the directional indications also change accordingly.

[0033] In addition, the description of "first", "second", etc. in the present application is only for the purpose of description, and cannot be understood as indicating or implying the relative importance of the indicated technical features or implicitly indicating the number of the indicated technical features. Therefore, the features limited by "first" and "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple groups" is at least two groups, such as two groups, three groups, etc., unless otherwise specifically limited.

[0034] In the present application, unless otherwise specifically defined and limited, the terms "connection", "fixation", etc. should be understood broadly, for example, "fixation" can be fixed connection, or detachable connection, or integral; can be mechanical connection, or electrical connection, or physical connection, or wireless communication connection; can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements, unless otherwise specifically limited. For those of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] In addition, the technical solutions of each embodiment of the present application can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can realize it, and when the combination of technical solutions appears contradictory or unachievable, it should be considered that the combination of technical solutions does not exist, nor is it within the scope of protection claimed by the present application.

[0036] The application provides an ion beam generation system based on laser and cone target interaction, which comprises a laser source, a vacuum target chamber, a transmission focusing device, a modulation solid target and a beam separation module. Figure 1 As shown in the figure, in one embodiment, the system comprises a laser source, a vacuum target chamber, a transmission focusing device, a modulation solid target and a beam separation module.

[0037] The connection relationship between the components is that the laser source is arranged outside the vacuum target chamber as an input end, the beam separation module is arranged outside the vacuum target chamber as an output end, the transmission focusing device and the modulation solid target are arranged inside the vacuum target chamber, and the components are spaced apart.

[0038] The laser source 1 generates laser. Preferably, the laser source generates linearly polarized femtosecond Gaussian laser, and the laser path is arranged vertically to the vacuum target chamber, the laser intensity of the femtosecond Gaussian laser is 10 20 ~10 22 W / cm 2 .

[0039] The vacuum target chamber 6 has an input window and an output window, laser is shot into the vacuum target chamber through the input window and shot out of the vacuum target chamber through the output window, so as to prevent the influence of laser propagation in air on laser parameters and conversion efficiency. It should be noted that the ion beam is shot out of the vacuum target chamber through the output window.

[0040] The transmission focusing device is used for transmitting and focusing laser on the modulation solid target. Preferably, the transmission focusing device comprises an optical transmission module 2 and a laser focusing module 3; the optical transmission module is arranged on the laser path and changes the direction of the laser to be shot into the laser focusing module, so as to protect the equipment; the laser focusing module receives the outgoing laser of the optical transmission module, changes the optical path and focuses to be shot into the modulation solid target.

[0041] The modulated solid target comprises: a planar target 8, the front surface of which is the surface of the planar target facing the input end, and the front surface of the planar target is provided with a pre-plasma 4 and / or a conical target 7, and the pre-plasma 4 and / or the conical target cover the entire front surface of the planar target to improve the energy conversion efficiency and the cut-off energy; the center line of the modulated solid target is perpendicular to the surface on which the planar target is located, and the center line of the modulated solid target is parallel to the outgoing laser of the laser focusing module; the pre-plasma is a critical density thin plasma, which is composed of pure hydrogen and is arranged on the front surface of the conical target or the planar target (for example, an injector 9 is used as an external injection device to inject the pre-plasma into the vacuum target chamber); the conical target is arranged between the plasma and the planar target or on the front surface of the planar target. Preferably, the conical target comprises: a body and a target groove; the body is a cylindrical structure, the front surface of which is the surface of the body facing the input end, and the front surface of the body is provided with the target groove recessed in the direction of the output end; the target groove is a conical structure, and the bottom surface of the target groove is coplanar with the front surface of the body; this arrangement can focus the laser and generate superhot electrons to further improve the energy conversion efficiency and the cut-off energy. Further preferably, the angle between the axis of the conical structure and any generatrix is 45°, so as to better focus the laser to improve the sheath electric field strength, thereby improving the maximum cut-off energy of the protons and the energy conversion efficiency from the laser energy to the proton energy. Still further preferably, when the front surface of the planar target is provided with the pre-plasma, the pre-plasma is a planar plate structure, one surface of which abuts against the front surface of the planar target, and the other surface faces the direction of the laser source; when the front surface of the planar target is provided with the pre-plasma and the conical target, the pre-plasma comprises: a first part and a second part, the first part is a planar plate structure and is connected with the second part, and the second part is a conical structure and the side surface of the second part abuts against the conical target. Still further preferably, the planar target uses a carbon-hydrogen target, and the carbon and hydrogen are mixed in a certain proportion. The embodiment does not limit the specific size of the modulated solid target, as long as the laser can be fully irradiated on the modulated solid target. The embodiment also does not limit the connection mode between the pre-plasma, the conical target and the planar target, and the specific connection mode can be achieved by using the prior art.

[0042] The beam separation module 5 separates the outgoing ion beam through the vacuum target chamber to generate an electron beam and a proton beam. Preferably, the beam separation module is two deflection magnets, which are arranged on the two sides of the output window and are both parallel to the outgoing direction of the ion beam, so as to generate a deflection magnetic field, deflect the outgoing electron beam, and generate the ion beam.

[0043] The working process of the present application is: a femtosecond Gaussian laser with linear polarization is generated by a laser source, the femtosecond Gaussian laser is shot into a vacuum target chamber through an input window, is reversed by an optical transmission module, is transmitted to a laser focusing module, in the laser focusing module, the laser focal spot is reduced, the energy density is further improved, the focused laser is shot along the axis of the modulation solid target and passes through the modulation solid target, the focused laser interacts with the modulation solid target to generate an ion beam, the ion beam is shot out of the vacuum target chamber through an output window, reaches a deflection magnetic field, the ion beam is shaped and deflected by the magnetic field, the electrons mixed in the ion beam are deflected, thereby realizing the separation of electrons and protons, generating a high-energy and high-conversion-efficiency ion beam, and the energy and conversion efficiency are significantly improved.

[0044] The working principle of the present application is: when the ultra-short and ultra-strong laser pulse generated by the laser source acts on the modulation solid target, the modulation solid target is a composite plasma structure and is instantaneously ionized into a plasma state. Under the action of resonance absorption, vacuum heating and other effects in the vacuum target chamber, the energy of the laser pulse is absorbed by the plasma of different structures and heated to generate superhot electrons, which continuously propagate forward in the modulation solid target and finally enter the vacuum region behind the modulation solid target to generate a superstrong electric field at the back of the target to accelerate the ion beam. The present application designs a modulation solid target which can interact with the laser pulse under the existing laser conditions, the focused laser passes through the pre-plasma, accelerates part of the ions and electrons, generates superhot electrons, and continues to act on the conical target and the planar target to push the electrons and protons of the target backward, further generates superhot electrons, when the superhot electrons propagate to the back surface of the target, a superstrong sheath electric field will be established behind the target, which is an ion acceleration field and can directly ionize the ions on the back surface of the target, accelerate the ions to a very high energy and emit them along the back normal with a certain solid angle, generating a high-energy ion beam with higher cutoff energy and higher energy conversion efficiency. The structure of the modulation solid target improves the energy conversion efficiency of the laser to the heated electrons, the cutoff energy is increased by about 540% compared to the ion beam generated by the same laser pulse incident on a planar solid target, and the energy conversion efficiency is increased by 510%.

[0045] The ion beam generation system based on the interaction of laser and cone target comprises a laser source, a vacuum target chamber, an optical transmission module, a laser focusing module, a modulation solid target and a deflection magnet. The modulation solid target comprises a pre-plasma, a cone target and a carbon-hydrogen plane target.

[0046] It should be noted that the laser source, the vacuum target chamber, the optical transmission module, the laser focusing module, the plane target, the beam separation module and the connection mode between the components are all prior art.

[0047] In one specific embodiment, the ion beam generation system based on the interaction of laser and cone target comprises a laser source, a vacuum target chamber, an optical transmission module, a laser focusing module, a modulation solid target and a deflection magnet. The modulation solid target comprises a pre-plasma, a cone target and a carbon-hydrogen plane target.

[0048] The laser source generates a linearly polarized Gaussian laser, the laser intensity is 10 20 ~ 10 22 W / cm 2 , the laser wavelength is Lambda = 1μm, the focal spot radius is 4 μm, the time configuration is ladder-shaped, including a rising edge and a falling edge of 1T0 and a platform distribution area of 10T0, T 0= c / Lambda , T0 is the laser period, c is the speed of light in vacuum, the normalized laser intensity is 10a0, the pulse width is 1.0 s, and the direction is perpendicular to the surface of the carbon-hydrogen plane target. The pre-plasma is composed of protons (H+) and electrons (e-). The thickness of the first part is 2000 nm, and the density of the pre-plasma is the critical density n cThe conical target is a gold conical target, the included angle between the axis and the generatrix is 45°, and the whole is kept electrically neutral by gold ions (Au+) and electrons (e-). The carbon-hydrogen plane target is composed of protons (H+), hexavalent ionized carbon ions (C6+) and electrons (e-), and the whole is kept electrically neutral, the thickness is 3000 nm, the hydrogen (proton) density is 50 n c , the carbon density is 25 n c , and the electron density is 200 n c , wherein, n c is the plasma critical density.

[0049] The laser source generates a linearly polarized Gaussian laser with an intensity of 1.37*10 20 W / cm 2 , and through the optical transmission module and the laser focusing module in the vacuum target chamber, the Gaussian laser is focused and acts on the surface of the modulated solid target along the axis of the modulated solid target to ionize the modulated solid target into a plasma state. Under the effects of resonant absorption and vacuum heating, the energy of the laser pulse is absorbed by the plasma and heated to generate superhot electrons, which continuously propagate forward in the modulated solid target and finally enter the vacuum area behind the modulated solid target. Under the shaping and deflection of the magnetic field, the electrons mixed in the ion beam generated by the modulated solid target are deflected to separate the electrons and the ions, and the ion beam generated by the modulated solid target has a much higher cutoff energy and energy conversion efficiency than the ion beam generated by the unmodulated plane solid target.

[0050] As shown in Figure 2 , the solid line is the proton energy spectrum obtained after the laser pulse interacts with the modulated solid target, and the dashed line is the proton energy spectrum obtained after the laser pulse interacts with the ordinary plane target. As can be seen from the comparison in the figure, the modulated solid target has a significant effect on the cutoff energy of the proton beam. Compared with the ordinary plane target, the cutoff energy of the ion beam generated by the modulated solid target is increased by about 540%.

[0051] As shown in Figure 3 , the solid line is the energy conversion efficiency from laser energy to proton energy after the laser pulse interacts with the modulated solid target, and the dashed line is the energy conversion efficiency from laser energy to proton energy after the laser pulse interacts with the ordinary plane target. As can be seen from the comparison in the figure, the modulated solid target has a significant effect on the energy conversion efficiency of the proton beam. Compared with the ordinary plane target, the energy conversion efficiency of the modulated solid target is increased by about 510%.

[0052] Any combination of the technical features in the above embodiments can be made, and for the sake of brevity, not all possible combinations are described, however, any combination of the technical features is deemed to be within the scope of the present disclosure as long as there is no inconsistency.

[0053] The above embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the patent scope of the present application. It should be pointed out that for ordinary skilled persons in the art, several modifications and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. Ion beam generation system based on laser and cone target interaction, characterized in that, The application relates to a laser source, a vacuum target chamber, a transmission focusing device, a modulation solid target and a beam separation module. The laser source is arranged outside the vacuum target chamber as an input end, the beam separation module is arranged outside the vacuum target chamber as an output end, and the transmission focusing device and the modulation solid target are arranged inside the vacuum target chamber. The modulation solid target comprises a plane target, the plane of which towards the input end is a front surface, and the front surface of the plane target is provided with a pre-plasma and / or a conical target. The laser source generates laser light, which is injected into the vacuum target chamber, passes through the transmission focusing device, is injected into the modulation solid target, and is emitted from the vacuum target chamber after interacting with the modulation solid target, and the beam separation module generates an ion beam with electrons and protons separated. The transmission focusing device comprises an optical transmission module and a laser focusing module.

2. The ion beam generation system based on laser and a conical target interaction according to claim 1, wherein, The optical transmission module is arranged on the light path of the laser light and changes the direction of the laser light before injecting the laser light into the laser focusing module. The laser focusing module receives the emitted laser light of the optical transmission module and focuses the laser light before injecting the laser light into the modulation solid target. The vacuum target chamber is provided with an input window and an output window, the laser light is injected into the vacuum target chamber through the input window and is emitted from the vacuum target chamber through the output window.

3. The ion beam generation system based on laser interaction with a conical target according to claim 2, wherein, The beam separation module is two deflection magnets, which are arranged on the two sides of the output window and are parallel to the emission direction of the ion beam. The conical target comprises a body and a target groove.

4. The laser-based ion beam generation system based on laser and cone target interaction of any of claims 1 to 3, characterized in that, The body is a cylindrical structure, the plane of the body towards the input end is a front surface, and the front surface of the body is provided with a target groove recessed towards the output end. The target groove is a conical structure, and the bottom surface of the target groove is coplanar with the front surface of the body. The angle between the axis of the conical structure and any generatrix is 45 degrees.

5. The ion beam generation system based on laser interaction with a conical target according to claim 4, wherein, When the front surface of the plane target is provided with a pre-plasma, the pre-plasma is a plane plate structure, one surface of which abuts against the front surface of the plane target and the other surface thereof is towards the direction of the laser source.

6. The ion beam generation system based on laser interaction with a conical target according to any one of claims 1 to 3, characterized in that, When the front surface of the plane target is provided with a pre-plasma and a conical target, the pre-plasma comprises a first part and a second part, the first part is a plane plate structure and is connected with the second part, and the second part is a conical structure and the side surface of the second part abuts against the conical target.

7. The ion beam generation system based on laser interaction with a conical target according to claim 6, wherein, The plane target adopts a carbon-hydrogen target.

8. The ion beam generation system based on laser interaction with a conical target according to any one of claims 1 to 3, characterized in that, The laser source generates linearly polarized femtosecond Gaussian laser light.

9. The ion beam generation system based on laser interaction with a conical target according to any one of claims 1 to 3, characterized in that, ​ 10. The ion beam generation system based on laser and a conical target interaction according to claim 9, characterized in that, The femtosecond Gaussian laser has an intensity of 10 20 ~10 22 W / cm 2 .

Images