CN118301836A

CN118301836A - High-pass angular uniform proton beam generation method

Info

Publication number: CN118301836A
Application number: CN202410597387.7A
Authority: CN
Inventors: 蒋祥瑞; 邹德滨; 邵福球
Original assignee: National University of Defense Technology
Current assignee: National University of Defense Technology
Filing date: 2024-05-14
Publication date: 2024-07-05

Abstract

The invention provides a high-flux angular uniform proton beam generation method, which is characterized in that a plurality of femtosecond laser pulses are focused on the spherical surface outside the hemispherical target surface of a filament-hemispherical target, a laser field heats electrons in the filament and the hemispherical target surface and sends the electrons to the target, an ultra-strong sheath electric field which is uniformly distributed is formed under the charge separation effect, and then the sheath electric field accelerates protons on the spherical surface inside the hemispherical target surface to generate a high-flux angular uniform proton beam. By the proposal provided by the invention, the nearly uniform distribution of proton angles between-90 degrees and 90 degrees is realized, and the peak flux and total number of protons are up to 3.26 multiplied by 10 ³⁰/cm²/s and 8.32 multiplied by 10 ¹⁶, which are improved by 4 times and 7 times compared with the proposal of single-beam laser incidence flat-plate targets.

Description

High-pass angular uniform proton beam generation method

Technical Field

The invention mainly relates to the technical field of proton beam generation, in particular to a high-flux proton beam generation method with uniform angular direction.

Background

The high-current pulse ion beam can quickly melt, evaporate, ablate and resolidify the surface of a substance in a very short time, and can generate local high-temperature high-density colloidal plasmas, so that the high-temperature high-density colloidal plasmas have wide application in the research field of material surface engineering, such as surface modification of metal materials, film growth and nano powder preparation. The pulse width of the high current pulsed ion beam generated by conventional means such as magnetically isolated ion diodes is typically 10 to 1000 nanoseconds. Over the past several decades, many efforts have been made to shorten ion beam pulse width in order to meet the needs of applications such as Inertial Confinement Fusion (ICF) and the production of temperature dense matter (WDM). The existing ion source based on accelerator or electric pulse can realize the pulse width of 1-10 nanoseconds, but the ion beam with the pulse width level can still generate hydrodynamic expansion in the process of heating materials, and isothermal heating is difficult to realize. Therefore, how to generate shorter pulsed ion beams remains a challenge to be addressed.

With the development of chirped pulse amplification technology, the pulse width of a strong laser pulse can be compressed to the picosecond or even femtosecond order. The ultra-short laser pulse is used as an energy driving source, and provides possibility for generating a pulse ion beam with picosecond pulse width. Ultrashort pulsed ion beams find important applications in studying basic material properties and temperature dense materials, in particular, in studying the state equation and opacity, and in studying the fuel compression and ignition processes in inertial confinement fusion. In most applications, in order to suppress hydrodynamic instabilities, it is desirable not only for the ion beam to have a high flux, but also to have a uniform distribution that matches the target profile. In order to improve the ion beam flux, arc-shaped structured targets capable of improving the focusing property of the ion beam have been proposed. Targets of this shape can be prepared by 3D printing and chemical vapor deposition methods. In addition, the damage of the laser pre-pulse to the target surface can be reasonably controlled by the laser cleaning technique. However, how to achieve proper beam spatial uniformity remains a challenge.

Disclosure of Invention

The invention provides a high-flux angular uniform proton beam generation method, which is characterized in that a plurality of femtosecond laser pulses are focused on the spherical surface outside the hemispherical target surface of a filament-hemispherical target, a laser field heats electrons in the filament and the hemispherical target surface and sends the electrons to the target, an ultra-strong sheath electric field which is uniformly distributed is formed under the charge separation effect, and then the sheath electric field accelerates protons on the spherical surface inside the hemispherical target surface to generate a high-flux angular uniform proton beam.

In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:

the invention provides a high-flux angularly uniform proton beam generation method, which comprises the following steps:

Constructing a wire-hemisphere target, wherein the wire-hemisphere target comprises a hemisphere target surface and a plurality of metal wires attached to the sphere outside the hemisphere target surface, and each metal wire is used as an incident port of one femtosecond laser pulse;

Multiple femtosecond laser pulses are simultaneously incident on a wire-hemispherical target through corresponding metal wires at different angles, wherein: the femtosecond laser pulse interacts with the metal wire, a laser electric field pulls out dense electron strings from the metal wire and efficiently targets the dense electron strings to accelerate the dense electron strings, then the femtosecond laser pulse reaches a hemispherical target surface, and electrons in the hemispherical target surface are heated and sent to a hemispherical cavity behind the hemispherical target surface; electrons with high energy density from the metal wire and the hemispherical target surface are uniformly distributed in the hemispherical cavity behind the hemispherical target surface, a sheath electric field distributed in an angle direction is formed under the charge separation effect, and protons on the spherical surface on the inner side of the hemispherical target surface are accelerated by the sheath electric field, so that a high-flux uniform-angle proton beam is generated.

Preferably, three metal wires are attached to the outer spherical surface of the hemispherical target surface, and three femtosecond laser pulses are respectively incident on the wire-hemispherical target at different angles through the corresponding metal wires. Further, one metal wire is coaxial with the central axis of the hemispherical target surface, and the other two metal wires are radially and symmetrically distributed.

Preferably, the three femtosecond laser pulses are each linearly polarized p-polarized femtosecond laser pulses with a wavelength of 1 μm, an intensity of 4.56X10 ¹⁹W/cm², a power of 6.4TW, an energy of 0.16J, a focal spot radius and a pulse width of 3 μm and 33fs, respectively.

Preferably, the material of the hemispherical target surface is hydrogen, the density of the hemispherical target surface is 5.6X10 ²²cm^-3, the outer diameter is 20 μm, and the thickness is 3 μm.

Preferably, the three metal wires are all copper wires, the density is 2.2X10 ²³cm^-3, the diameter is 1 μm, the length is 5 μm, and three femtosecond laser pulses are respectively incident along the central axis of the corresponding metal wires.

On the other hand, a high-flux uniform-angle proton beam generating device is provided, which comprises a wire-hemisphere target, wherein the wire-hemisphere target comprises a hemisphere target surface and a plurality of metal wires attached to the outer spherical surface of the hemisphere target surface, and each metal wire is used as an incident port of one femtosecond laser pulse.

The time delay between the current multiple lasers can be controlled to a femtosecond time precision and the spatial deviation can also be controlled to a micrometer scale. That is, it has been possible to control the interaction process of multiple femtosecond laser pulses with the plasma very precisely. Therefore, the scheme of generating a high-flux angularly uniform proton beam by using multiple lasers is a very suitable choice in terms of improving both ion beam flux and spatial uniformity. Based on this, the present invention proposes a high-flux angularly uniform proton beam generation scheme. When multiple femtosecond laser pulses are simultaneously incident on a wire-hemispherical target at different angles, the laser pulses firstly interact with a metal copper wire attached to the outer spherical surface of the hemispherical target surface, and a laser electric field pulls out a dense electron string from the metal copper wire and accelerates the dense electron string after efficiently targeting the target. The laser pulse then reaches the hemispherical target surface, and electrons in the hemispherical target surface are heated and sent behind the target (i.e., the hemispherical cavity behind the hemispherical target surface) by a "hole-making" process. After electrons with high energy density from the metal copper wire and the hemispherical target surface are uniformly distributed on the target, an ultra-strong sheath electric field with uniform angular direction is formed under the charge separation effect, protons are accelerated by a target back sheath ion acceleration mechanism, and the proton beam with uniform angular direction and high symmetry is obtained. The protons move in collimation towards the central region of the cavity behind the target, forming a high-flux angularly uniform proton beam. By the proposal provided by the invention, the nearly uniform distribution of proton angles between-90 degrees and 90 degrees is realized, and the peak flux and total number of protons are up to 3.26 multiplied by 10 ³⁰/cm²/s and 8.32 multiplied by 10 ¹⁶, which are improved by 4 times and 7 times compared with the proposal of single-beam laser incidence flat-plate targets. The invention is expected to be applied to fields of laboratory celestial physics, basic material science, controllable nuclear fusion and the like.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic diagram of a proton beam generation method providing high-flux angular uniformity in one embodiment;

FIG. 2 is a schematic diagram of three comparative schemes in a comparative example, where (a) is a three-beam laser-incident hemispherical target scheme, (b) is a single-beam laser-incident hemispherical target scheme, and (c) is a single-beam laser-incident planar target scheme;

Fig. 3 is a schematic diagram of proton flux, angular distribution, energy spectrum and energy conversion efficiency of laser to protons for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), where (a) is a graph comparing proton flux evolution over time for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), (b) is a graph comparing angular distribution of protons after target at time 100T ₀ for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), (c) is a graph comparing proton energy spectrum for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme) at time 100T ₀, and (d) is a graph comparing energy conversion efficiency of laser to protons for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme) at time 100T ₀;

Fig. 4 is a schematic diagram of electron energy density distribution, electron trajectory, electron energy spectrum and energy conversion efficiency from laser to electrons, in which (a) is an energy density distribution of post-target hot electrons at time 100T ₀ of four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), fig. 4 (b 1) shows an energy density distribution of electrons from wires at time 55T ₀ of TWH scheme, fig. 4 (b 2) -4 (b 4) show motion trajectories and transverse electric field distribution of electrons in a single wire in the middle of three times 45T ₀、50T₀、55T₀ of TWH scheme, respectively, fig. 4 (c) is a time evolution comparison graph of total energy density of post-target electrons of four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), and fig. 4 (d) is an electron energy spectrum comparison graph of four schemes (TWH scheme, TH scheme, SH scheme, SP scheme); fig. 4 (e) is a graph comparing energy conversion efficiency of laser to electron in four schemes (TWH scheme, TH scheme, SH scheme, SP scheme);

Fig. 5 is a schematic diagram showing the electric field distribution of the sheath layer, wherein fig. 5 (a) is a graph showing the electric field distribution of the sheath layer after the target at the time of 50T ₀ in four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), and fig. 5 (b) is a graph showing the electric field intensity distribution of the four schemes (TWH scheme, TH scheme, SH scheme, SP scheme) at 0.3 μm after the target; FIG. 5 (c) is a graph showing the time evolution of the total electric field strength and the electric field area of the region where the field strength is higher than the threshold value 3.2TV/m for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme);

Fig. 6 is a schematic diagram of proton trajectories and energy density distributions of the TWH scheme, wherein (a) is a graph showing the evolution of the movement of 30 typical protons in the TWH scheme over time, and fig. 6 (b) is a graph showing the energy density distribution of protons in a circular region after the target at the time point 300T ₀ in comparison with four schemes (TWH scheme, TH scheme, SH scheme, SP scheme);

Fig. 7 is a schematic diagram of the effect of the laser incidence angle of the TWH scheme on the proton angular distribution and flux, where (a) is a schematic diagram of the effect of the laser incidence angle of the TWH scheme on the proton angular distribution, (b) is a schematic diagram of the effect of the laser incidence angle of the TWH scheme on the proton peak flux and the total number of protons, (c) is a schematic diagram of the effect of the deviation angle of the laser incidence direction of the TWH scheme from the central axis of the filament on the proton angular distribution, and (d) is a schematic diagram of the effect of the deviation angle of the laser incidence direction of the TWH scheme from the central axis of the filament on the proton flux.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

In one embodiment, a method for generating a high-flux angularly uniform proton beam is provided, comprising:

Constructing a wire-hemisphere target, wherein the wire-hemisphere target comprises a hemisphere target surface 100 and a plurality of metal wires 200 attached to a sphere 101 outside the hemisphere target surface, and each metal wire 200 is used as an incident port of one femtosecond laser pulse 300;

A plurality of femtosecond laser pulses 300 are simultaneously incident to a wire-hemispherical target at different angles through corresponding wires 200, wherein: the femtosecond laser pulse 300 interacts with the metal wire 200 first, the laser electric field pulls out dense electron strings from the metal wire 200 and efficiently targets the dense electron strings to accelerate, then the femtosecond laser pulse reaches the hemispherical target surface 100, and electrons in the hemispherical target surface 100 are heated and sent to a hemispherical cavity behind the hemispherical target surface; electrons 400 of high energy density from the wire 200 and hemispherical target 200 are uniformly distributed in the hemispherical cavity behind hemispherical target 100, forming an angularly distributed sheath electric field under the charge separation effect, and accelerating protons 500 of sphere 102 inside the hemispherical target by the sheath electric field, resulting in a high-flux angularly uniform proton beam 600.

It will be appreciated that the wire-hemispherical target includes a hemispherical target surface 100 and a plurality of wires 200 attached to the spherical surface 101 outside the hemispherical target surface, wherein the number of wires 200 is not limited, and the wires 200 are respectively used as the incident ports of the femtosecond laser pulses 300, so that the number of wires 200 is consistent with the number of beams of the femtosecond laser pulses 300, i.e., each of the femtosecond laser pulses 300 corresponds to one wire. Further, in order to achieve uniform distribution of the proton beam, the wires also need to be uniformly distributed on the front surface of the hemispherical target.

Referring to the embodiment shown in fig. 1, three wires 200 are attached to the outer sphere 101 of the hemispherical target surface, and three femtosecond laser pulses 300 are respectively incident on the wire-hemispherical target at different angles through the corresponding wires 200. One metal wire is coaxial with the central axis of the hemispherical target surface, and the other two metal wires are radially and symmetrically distributed. The three femtosecond laser pulses 300 are all linearly polarized p-polarized femtosecond laser pulses with a wavelength of 1 μm, an intensity of 4.56X10 ¹⁹W/cm², a power of 6.4TW, an energy of 0.16J, a focal spot radius and a pulse width of 3 μm and 33fs, respectively. The material of the hemispherical target surface 100 is hydrogen, the density of the hemispherical target surface 100 is 5.6X10 ²²cm^-3, the outer diameter is 20 μm, and the thickness is 3 μm. The three wires 200 are copper wires, the density is 2.2x10 ²³cm^-3, the diameter is 1 μm, the length is 5 μm, and the three femtosecond laser pulses 300 are respectively incident along the central axis of the corresponding wire 200. Three femtosecond laser pulses 300 are respectively incident on the wire-hemispherical target at an incident angle of-60 °,0 °, and 60 ° via the corresponding wire 200.

Further, the material of hemispherical target surface 100 may be tailored, specifically based on the ion beam to be obtained, such as a proton beam, a hydrogen target, a carbon ion beam, and a carbon target. Parameters of the target: the density is basically guaranteed, parameters such as the solid density, the outer diameter, the thickness and the like can be adjusted, but parameters such as the laser focal spot and the like are required to be adjusted synchronously to ensure the uniformity of the generated ion beam.

The material of the wire 200 may be also adjustable, and in order to obtain a large amount of electrons, the material of the wire 200 may be copper, aluminum, gold, or the like.

The embodiment shown in fig. 1 is defined as a three-beam laser-incident wire-hemispherical target solution, abbreviated as TWH (three laserbeams IRRADIATING AWIRE-hemisphere), and fig. 2 is a schematic diagram of three comparative solutions in a pair of examples, where (a) is a three-beam laser direct-incident hemispherical target solution, abbreviated as TH (THREE LASER beams IRRADIATING A HEMISPHERE), (b) is a single-beam laser-incident hemispherical target solution, abbreviated as SH (single laserbeam IRRADIATING A HEMISPHERE), and (c) is a single-beam laser-incident flat-plate target solution, abbreviated as SP (single laserbeam IRRADIATING PLANARTARGET). In fig. 2 (a), three laser beams directly enter the hemispherical target solution TH, i.e. the three wires in fig. 1 are eliminated, and the three laser beams directly enter the hemispherical target surface. In the single-beam laser incidence hemispherical target scheme SH in fig. 2 (b), namely, two lasers which are radially symmetrically distributed are canceled while three wires in fig. 1 are canceled, only the lasers which are coaxially incident with the central axis of the hemispherical target surface are reserved, and the single-beam lasers are directly incident to the hemispherical target surface. The laser, laser incidence angle, hemispherical target surface used in the comparative schemes shown in fig. 2 (a), 2 (b) are all identical to the arrangement in the embodiment shown in fig. 1. The laser used in the comparison scheme shown in fig. 2 (c) is identical to the laser parameters in the embodiment shown in fig. 1, and the planar target in fig. 2 (c) is identical to the hemispherical target surface in the embodiment shown in fig. 1.

In order to study the physical process of multi-beam laser driven filament-hemispherical targets to produce high-flux angularly uniform proton beams, numerical simulations were performed using the two-dimensional particle simulation program, EPOCH. At the center of the post-target cavity, a1 μm radius sample was assumed and proton information was counted across the sample surface. The proton fluxes of the three-beam laser incident wire-hemisphere target scheme provided in the embodiment shown in fig. 1 and the three comparison schemes in fig. 2 evolve with time as shown in fig. 3 (a), it can be seen that the peak proton fluxes and the total number of the TWH scheme are as high as 3.26×10 ³⁰/cm²/s and 8.32×10 ¹⁶, respectively, and are improved by 4 times and 7 times compared to the SP scheme, and are improved by nearly 2 times compared to the other two schemes, because the wire improves the energy absorption efficiency of the laser and achieves a more uniform laser intensity distribution at the front surface of the hemisphere. Fig. 3 (b) is an angular distribution of protons after the target at time 100T ₀, and it can be seen that by using multiple lasers, the angle of protons (relative to the x-axis) is more evenly distributed between-90 ° and 90 °.

The angular distribution of protons in the TWH scheme is more uniform than that of TH scheme, because the filaments act as a buffer for the gaussian laser light, resulting in a more uniform angular distribution of light intensity. The angular uniformity of protons can be described by two parameters, namely, the average deviation angle and the standard deviation of the angular distribution, wherein the deviation angle refers to the included angle between the movement direction of the protons and the line connecting the position of the protons with the center of the sample. For the SP scheme, the mean deviation angle and angular distribution standard deviation were 28 ° and 9.8x10 ¹⁴, respectively, while for the TWH scheme, the mean deviation angle and angular distribution standard deviation were only 4.6 ° and 3.6x10 ¹³, indicating that almost all spatial protons in the TWH scheme are moving towards the sample, which is advantageous for isovolumetric heating of the material. Fig. 3 (c) and 3 (d) show proton spectra and laser-to-proton energy conversion efficiencies at time point 100T ₀. It can be seen that the TWH scheme also has advantages in terms of increasing proton energy, with maximum proton energy, proton temperature and laser to proton energy conversion efficiencies of 9MeV, 2.2MeV and 12%, respectively, for the SP scheme these values are only 5MeV, 0.9MeV and 5%. Note that the maximum energy of protons for TH and SP schemes is comparable to the energy conversion efficiency of laser to protons, while being lower than for TWH and SH schemes, since proton acceleration is also affected by laser intensity in addition to wire configuration and arc structure targets.

Fig. 4 shows a schematic diagram of electron energy density distribution, electron trajectories, electron energy spectra, and energy conversion efficiency of laser to electron for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme). Fig. 4 (a) compares the energy density distribution of the post-target hot electrons for the four schemes (TWH scheme, TH scheme, SH scheme, SP scheme) at time point 100T ₀, and it can be seen that the post-target electron energy density in the TWH scheme is more uniformly distributed in the angular direction, and the electrons originate from the filament and hemisphere. Fig. 4 (b 1) shows the energy density distribution of electrons from the filament at time 55T ₀, and it can be seen that the electrons are distributed in the form of an angular periodic electron train. Fig. 4 (B2) -4 (B4) show the motion trajectory and the transverse electric field distribution of electrons in the middle single wire at three moments of 45T ₀、50T₀、55T₀, and it can be seen that the electrons are first pulled out from the surface of the copper wire by the laser transverse electric field and then accelerated under the action of v×b force, and most of the electrons are well confined to the rear surface of the target due to the confinement effect of the electric field of the charge separation sheath shown in fig. 5 (a), as shown in fig. 4 (B4). In contrast, in the SH and SP schemes, the hot electrons are distributed primarily in the rear axial focal spot region of the target. Fig. 4 (c) shows the time evolution of the total electron energy density after the target, and it can be seen that almost all of the electrons in the TWH scheme have several times the electron energy density of the other schemes at all times, and almost all of the electrons with high energy density are contributed by the copper wire in the period of 40T ₀ to 60T ₀. As shown in the electron energy spectrum of fig. 4 (d), the highest hot electron temperatures and energies in the TWH scheme are 3.2MeV and 19.4MeV, respectively, and most of the electrons with energies above 4MeV originate from the copper wire. Fig. 4 (e) shows the energy conversion efficiency of the laser to the electrons in the four schemes, and it can be seen that the TWH scheme is as high as 39%, which is significantly higher than the other schemes, and the energy conversion efficiency of the laser to the electrons in the filament is 31%.

Fig. 5 (a) shows the sheath electric field distribution after the target at time 50T ₀, the arrows in the figure represent the electric field magnitude and direction, and it can be seen that the post-target electric field is directed to the central region of the cavity in the TWH scheme. Furthermore, the sheath electric field is stronger in the TWH scheme than in the TH scheme because the TWH scheme has a higher electron temperature, and the sheath electric field strength is positively correlated with the electron temperature. Fig. 5 (b) shows the electric field intensity distribution at 0.3 μm after the target, and the uniformity of the sheath electric field can be described by the standard deviation of the field intensity distribution, as shown in the inset of fig. 5 (b), it can be seen that the standard deviation is the smallest in the TWH scheme, meaning that the field distribution is the most uniform. Fig. 5 (c) shows the total electric field strength and the time evolution of the electric field area in the region with the field strength higher than the threshold value 3.2TV/m, and it can be seen that both have the same trend, and the result of the TWH scheme is significantly higher than other schemes, which also explains the phenomenon that the maximum energy of protons and the energy conversion efficiency of laser light into protons are the highest in the TWH schemes shown in fig. 3 (c) and 3 (d).

Fig. 6 (a) shows the evolution over time of the movement of 30 typical protons in the TWH scheme, dividing the rear semicircular region of the target into 30 parts, randomly extracting 1 proton from each part region, resulting in the 30 protons. It can be seen that the trajectories of these protons are very symmetrical, the protons are aimed at the sample, a higher flux is achieved, as shown in fig. 3 (b) and 3 (a). Fig. 6 (b) shows the energy density distribution of protons in the circular region after the target at time 300T ₀ for four schemes (TWH scheme, TH scheme, SH scheme, SP scheme), consistent with expectations, a relatively large high energy density proton bright spot appears in the TWH scheme.

Fig. 7 shows the effect of laser incidence angle on proton angular distribution and proton flux in the TWH scheme, with simultaneous symmetrical variation of the angles of the upper and lower filaments. As can be seen from fig. 7 (a), as the laser incidence angle decreases, the proton angle distribution becomes similar to that of the single-beam laser scheme, that is, the SH scheme, and becomes more uniform as the laser incidence angle becomes larger. However, as can be seen from fig. 7 (b), the effect of the laser incidence angle on the proton peak flux and the total number of protons is small, because when the laser incidence angle is small, the interference effect between the optical fields increases the laser field strength, compensating for the loss in proton uniformity.

In fact, factors such as laser focal spot jitter make it difficult to achieve accurate incidence of laser along the wire center axis in experiments, and fig. 7 (c) and 7 (d) show the influence of the deviation angle of the incidence direction of laser and the wire center axis on the proton angle distribution and proton flux, respectively. It can be seen that as the incidence deviation angle increases, the optimizing effect of the wire on the proton angular distribution becomes weaker, and the proton angular distribution exhibits several peaks, resulting in a decrease in proton peak flux and total number. However, even if the incidence deviation angle reaches 10 °, the proton peak flux and the total number are reduced by only less than 10%.

The invention is not a matter of the known technology.

The technical features of the above embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the application, which are described in detail and are not to be construed as limiting the scope of the application. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the application, which are all within the scope of the application. Accordingly, the scope of protection of the present application is to be determined by the appended claims.

The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for generating a high-pass angularly uniform proton beam, comprising:

2. The high-pass angular uniform proton beam generating method as recited in claim 1, wherein: three metal wires are attached to the outer spherical surface of the hemispherical target surface, and three femtosecond laser pulses are respectively incident to the wire-hemispherical target at different angles through the corresponding metal wires.

3. The high-pass angular uniform proton beam generating method as recited in claim 2, wherein: one metal wire is coaxial with the central axis of the hemispherical target surface, and the other two metal wires are radially and symmetrically distributed.

4. The high-pass angular uniform proton beam generating method as recited in claim 3, wherein: the three femtosecond laser pulses are all linearly polarized p-polarized femtosecond laser pulses with the wavelength of 1 μm, the intensity of 4.56X10 ¹⁹W/cm², the power of 6.4TW, the energy of 0.16J, and the focal spot radius and pulse width of 3 μm and 33fs respectively.

5. The high-pass angularly uniform proton beam generation method according to claim 3 or 4, wherein: the material of the hemispherical target surface is hydrogen, the density of the hemispherical target surface is 5.6X10 ²²cm^-3, the outer diameter is 20 μm, and the thickness is 3 μm.

6. The high-pass angularly uniform proton beam generation method according to claim 5, wherein: the three metal wires are all copper wires, the density is 2.2X10 ²³cm^-3, the diameter is 1 μm, the length is 5 μm, and the three femtosecond laser pulses are respectively incident along the central axis of the corresponding metal wire.

7. The high-pass angularly uniform proton beam generation method according to claim 5, wherein: three femtosecond laser pulses are respectively incident on the wire-hemispherical target at the incident angles of-60 degrees, 0 degrees and 60 degrees through corresponding metal wires.

8. The proton beam generating device with uniform high-pass angular direction is characterized by comprising a wire-hemisphere target, wherein the wire-hemisphere target comprises a hemisphere target surface and a plurality of metal wires attached to the outer spherical surface of the hemisphere target surface, and each metal wire is used as an incident port of one femtosecond laser pulse.

9. The high-flux, angularly uniform proton beam generating device according to claim 8, wherein: three metal wires are attached to the outer spherical surface of the hemispherical target surface, and three femtosecond laser pulses are respectively incident to the wire-hemispherical target at different angles through the corresponding metal wires.

10. The high-pass angularly uniform proton beam generating device according to claim 9, wherein: one metal wire is coaxial with the central axis of the hemispherical target surface, and the other two metal wires are radially and symmetrically distributed.