阅读说明：本技术 一种测量黑腔m带x射线辐射对称性的方法 (Method for measuring symmetry of X-ray radiation in black cavity M-band ) 是由 李琦 郭亮 赵航 李志超 龚韬 潘凯强 李三伟 蒋小华 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种测量黑腔M带X射线辐射对称性的方法,首先将黑腔、单能通道、针孔阵列、微通道板和X射线成像设备的中心都放在在同一条直线上,其中黑腔两侧壁的中心开有诊断孔,将靶球涂上荧光材料,放置在黑腔中心；将激光射入黑腔,激光在黑腔内转换成软X射线和M带X射线,M带X射线会照射在靶球上会诱发特征荧光,特征荧光从诊断孔射出,经单能通道、针孔阵列和微通道板后,在X射线成像设备上得到单能的靶球荧光图像,由于荧光强度与M带X射线的强度成正比,所以通过靶球荧光图像,可以计算得到M带X射线的对称性。本发明可以通过荧光材料的阈值特性,将软X射线和M带X射线分离开来,实现对黑腔M带X射线辐射对称性的分频测量。(The invention discloses a method for measuring the symmetry of X-ray radiation in a black cavity M, which comprises the following steps of firstly, placing the centers of the black cavity, a single-energy channel, a pinhole array, a microchannel plate and an X-ray imaging device on the same straight line, wherein the centers of two side walls of the black cavity are provided with diagnostic holes, coating a target ball with a fluorescent material, and placing the target ball in the center of the black cavity; the laser is emitted into the black cavity, the laser is converted into soft X rays and M-band X rays in the black cavity, the M-band X rays can irradiate on the target ball to induce characteristic fluorescence, the characteristic fluorescence is emitted from a diagnosis hole, and a single-energy target ball fluorescence image is obtained on X-ray imaging equipment after passing through a single-energy channel, a pinhole array and a microchannel plate. The invention can separate the soft X-ray from the M-band X-ray through the threshold characteristic of the fluorescent material, thereby realizing the frequency division measurement of the symmetry of the black cavity M-band X-ray radiation.)

1. A method of measuring symmetry of X-ray radiation in a black cavity M-band, comprising the steps of:

s1, setting a measuring device; the measuring device comprises a black cavity, a single-energy channel, a pinhole array, a microchannel plate and X-ray imaging equipment which are sequentially arranged at intervals, wherein the centers of the black cavity, the single-energy channel, the pinhole array, the microchannel plate and the X-ray imaging equipment are positioned on the same straight line;

s2, coating a layer of fluorescent material on the surface of the target ball, and arranging the target ball in the center of the black cavity;

s3, emitting laser into the black cavity, and obtaining a single-energy target ball fluorescence image on the X-ray imaging equipment;

and S4, calculating to obtain the symmetry of the M-band X-ray radiation by using the fluorescence image of the target ball.

2. The method according to claim 1, wherein the black cavity is a cavity which is used for indirect drive laser fusion research and is provided with through holes at the upper part and the lower part and is communicated with the middle part, the method is characterized in that two diagnostic holes are respectively arranged on two side walls of the black cavity, and the angle formed by the normal lines of the two diagnostic holes is 180 degrees.

3. The method of claim 2, wherein the centers of the diagnostic well, the monoenergetic channels, the pinhole array, the microchannel plate, and the X-ray imaging device are all located on a same line.

4. The method of claim 3, wherein in step S3, laser is injected from the through hole and converted into soft X-ray and M-band X-ray on the black cavity wall, the M-band X-ray induces the characteristic fluorescence of the fluorescent material on the target ball, the characteristic fluorescence is emitted out of the black cavity through the diagnostic hole, the characteristic fluorescence passes through the monoenergetic channel, the pinhole array and the microchannel plate in sequence, and finally the fluorescence image of the target ball is obtained on the X-ray imaging device.

5. The method according to claim 1, wherein in step S4, the fluorescence image of the target ball is used to obtain an angular distribution f (θ) of fluorescence intensity, and f (θ) is expanded according to legendre polynomial to obtain:

coefficient of expansionThe obtained radiation asymmetry of each order of the M-band X-ray in the black cavity is c₁/c₀，c₂/c₀，c₃/c₀......c_l/c₀In which P is_l(cos θ) is a Legendre polynomial of degree l.

6. The method of claim 1, wherein in step S2, the target sphere is a solid hydrocarbon sphere at the center, and the outer layer of the fluorescent material is a silicon fluorescent material.

7. The method of claim 6, wherein the thickness of the silicon fluorescent material is 5-10 μ M.

8. The method of claim 1, wherein the single energy channel is a Ross filter or a spherical flexor for X-ray single energy gating.

9. The method of claim 1, wherein in step S3, the fluorescence images are monoenergetic X-ray images of the fluorescence of the target ball at different time periods.

Technical Field

The invention belongs to the technical field of indirect drive laser fusion, and particularly relates to a method for measuring symmetry of X-ray radiation in a black cavity M-band.

Background

In the indirect drive laser fusion, an ablation layer on the surface of the target pellet is heated by X rays in the black cavity to generate inward thrust, and finally the target pellet forms a high-temperature high-density central hot spot and realizes fusion ignition. Black cavity radiation symmetry is an important basis for achieving fusion ignition. When the radiation field is symmetrical, the target pill tends to ideal spherical compression, the compression efficiency is highest, and the hot spot temperature and density are higher; when the radiation field is asymmetric, the target pellet deviates from spherical compression, the compression efficiency is reduced, and the hot spot temperature and density are also reduced. Therefore, studying the radiation symmetry of the target pellet surface is of great importance for understanding the target pellet compression process.

The X-rays within the black cavity are typically divided by energy into soft X-rays and high energy M-band X-rays. The emission characteristics of the M-band X-rays, which are generated mainly near the corona plasma where the electrons are at a higher temperature and at a lower density, result in a more asymmetric distribution of the M-band X-rays. At present, experimental methods such as hot spot core self-luminous imaging, high-Z target ball re-luminous imaging, shock wave velocity measurement and the like are commonly adopted in indirect drive laser fusion research to measure the radiation symmetry of a black cavity. However, these experimental methods can only measure the radiation symmetry distribution of the full-band, and cannot measure the radiation symmetry distribution of the divided M-band X-ray. Simulation results show that the asymmetry of the frequency-divided M-band X-ray radiation also has important influence on the target pill compression process. Therefore, the accurate measurement of the symmetry of the M-band X-ray radiation facilitates accurate assessment of its effect on the target pellet compression process.

Disclosure of Invention

The invention aims to provide a method for measuring the symmetry of X-ray radiation in an M-band of a black cavity. Selecting energy from fluorescent powder emitted by a target ball through a single-energy channel, and finally forming a space-time resolution single-energy fluorescent image on X-ray imaging equipment through a pinhole array and a microchannel plate; and obtaining the intensity angle distribution of the fluorescence image through the fluorescence image of the target ball, and further obtaining the symmetry of the radiation of the M-band X-rays.

The purpose of the invention is realized by the following technical scheme: a method of measuring symmetry of X-ray radiation in a black cavity M-band, comprising the steps of:

s1, setting a measuring device; the measuring device comprises a black cavity, a single-energy channel, a pinhole array, a microchannel plate and X-ray imaging equipment which are sequentially arranged at intervals, wherein the centers of the black cavity, the single-energy channel, the pinhole array, the microchannel plate and the X-ray imaging equipment are positioned on the same straight line;

s2, coating a layer of fluorescent material on the surface of the target ball, and arranging the target ball in the center of the black cavity;

s3, emitting laser into the black cavity, and obtaining a single-energy target ball fluorescence image on the X-ray imaging equipment;

and S4, calculating to obtain the symmetry of the M-band X-ray radiation by using the fluorescence image of the target ball.

The surface of the target ball is coated with a layer of fluorescent material, the M-band X-ray in the black cavity can induce the characteristic fluorescence of the fluorescent material, the soft X-ray can not induce the fluorescence, the characteristic fluorescence can be subjected to energy selection through a single-energy channel, and then subjected to pinhole array imaging and a microchannel plate, and finally a space-time resolution single-energy target ball fluorescence image is formed on an X-ray imaging device. Since the intensity of the fluorescence emitted by the target ball is proportional to the intensity of the M-band X-ray, the intensity angle distribution of the fluorescence image of the target ball is equivalent to the symmetry distribution of the M-band X-ray radiation, so that the symmetry of the M-band X-ray radiation can be obtained through the intensity angle distribution of the fluorescence image.

Preferably, the black cavity is a cavity which is used for indirectly driving laser fusion research and is provided with through holes at the upper part and the lower part and is communicated with the middle part, and is characterized in that two diagnostic holes are respectively arranged on two side walls of the black cavity, and the angle formed by the normal lines of the two diagnostic holes is 180 degrees.

The black cavity adopted by the invention is a black cavity used in indirect drive laser fusion research, and is different from the black cavity in that two diagnostic holes are formed in the side wall of the black cavity and are used for carrying out symmetry measurement on M-band X rays.

Preferably, the centers of the diagnostic well, the monoenergetic channel, the pinhole array, the microchannel plate, and the X-ray imaging device are all located on the same straight line.

Aligning the center of the diagnostic well with the center of the measurement device ensures that the characteristic fluorescence can be injected into the measurement device.

Preferably, in step S3, laser is incident from the through hole and converted into soft X-rays and M-band X-rays on the black cavity wall, the M-band X-rays induce characteristic fluorescence of fluorescent material on the target ball, the characteristic fluorescence is emitted out of the black cavity through the diagnostic hole, the characteristic fluorescence sequentially passes through the single-energy channel, the pinhole array and the microchannel plate, and finally a single-energy target ball fluorescence image is obtained on the X-ray imaging device.

The characteristic fluorescence firstly carries out single energy selection through a single energy channel, then carries out pinhole array imaging, then passes through a microchannel plate for time resolution, and finally reaches a target ball fluorescence image on an X-ray imaging device.

Preferably, in step S4, the fluorescence intensity angular distribution f (θ) is obtained by using the fluorescence image of the target ball, and f (θ) is expanded by legendre polynomial to obtain:

coefficient of expansionThe obtained radiation asymmetry of each order of the M-band X-ray in the black cavity is c₁/c₀，c₂/c₀，c₃/c₀......c_l/c₀In which P is_l(cos θ) is a Legendre polynomial of degree l.

Since the intensity of the fluorescence emitted by the target ball is proportional to the intensity of the X-ray in the M band, the intensity angle distribution of the fluorescence image of the target ball is equivalent to the symmetry distribution of the X-ray radiation in the M band, and the symmetry of the X-ray radiation in the M band can be obtained through the intensity angle distribution of the fluorescence image.

Preferably, the target ball is a solid hydrocarbon ball at the center, and the outer layer is coated with a silicon fluorescent material.

By adopting the silicon fluorescent material and utilizing the fluorescent characteristic of the silicon fluorescent material, the M-band X-ray in the black cavity can induce fluorescence after irradiating on the silicon fluorescent material coating, and the soft X-ray can not induce fluorescence, so that the intensity of the M-band X-ray is in direct proportion to the fluorescence intensity, and the symmetry measurement of the M-band X-ray is convenient to carry out subsequently.

Preferably, the thickness of the silicon fluorescent material is 5-10 μm.

Preferably, the single-energy channel is a Ross filter or a spherical curved crystal for X-ray single-energy gating.

Preferably, in step S3, the fluorescence image is a monoenergetic X-ray image of the fluorescence of the target ball at different time periods.

Because the symmetry of the black cavity M-band X-ray radiation is changed along with time, the time evolution of the symmetry of the M-band X-ray radiation can be obtained by recording fluorescence images at different moments.

The main scheme and the further selection schemes can be freely combined to form a plurality of schemes which are all adopted and claimed by the invention; in the invention, the selection (each non-conflict selection) and other selections can be freely combined. The skilled person in the art can understand that there are many combinations, which are all the technical solutions to be protected by the present invention, according to the prior art and the common general knowledge after understanding the scheme of the present invention, and the technical solutions are not exhaustive herein.

The invention has the beneficial effects that:

the silicon fluorescent material is coated on the target ball, the characteristic fluorescence of the silicon fluorescent material can be induced only by the M-band X rays, the soft X rays and the M-band X rays are distinguished by using the threshold characteristic of fluorescence emission, and the frequency division measurement of the radiation symmetry of the black cavity M-band X rays is realized. The characteristic fluorescence emitted from the diagnosis hole is subjected to energy selection through a single-energy channel, is imaged through a pinhole array, and finally passes through a micro-channel plate for time resolution to form a space-time resolution single-energy fluorescence image on an X-ray imaging device. The intensity of the target ball single-energy fluorescence image is proportional to the intensity of the M-band X-ray, and the radiation symmetry of the M-band X-ray can be calculated by using the target ball single-energy fluorescence image.

Drawings

FIG. 1 is a flow chart of the method of the present invention.

Fig. 2 is a schematic structural diagram of the measuring device of the present invention.

Fig. 3 is a fluorescent image of a target sphere according to an embodiment of the present invention.

FIG. 4 is a graph of the intensity angle distribution of a fluorescent image of a target sphere according to an embodiment of the present invention.

Wherein, the names corresponding to the reference numbers are: 1-black cavity; 2-a diagnostic well; 3-target ball; 4-a monoenergetic channel; 5-pinhole array; 6-microchannel plate; 7-X-ray imaging equipment.

Detailed Description

The following non-limiting examples serve to illustrate the invention.

Example 1:

referring to fig. 1, a method for measuring symmetry of X-ray radiation in a black cavity M band includes the steps of:

s1, setting a measuring device; the measuring device comprises a black cavity, a single-energy channel, a pinhole array, a microchannel plate and X-ray imaging equipment which are sequentially arranged at intervals, wherein the centers of the black cavity, the single-energy channel, the pinhole array, the microchannel plate and the X-ray imaging equipment are positioned on the same straight line.

Referring to fig. 2, the black cavity 1, the single energy channel 4, the pinhole array 5, the microchannel plate 5 and the X-ray imaging apparatus are aligned in the center and spaced apart. The interval between each device is adjusted according to the measuring conditions of practical application, and the characteristic fluorescence can be ensured to obtain a complete and clear target ball fluorescence distribution image on the X-ray imaging device.

When the method is used for measuring the X-ray of the black cavity M, the adopted black cavity 1 is a columnar cavity which is used for indirect drive laser fusion research, is provided with holes at the upper part and the lower part and is communicated with the middle part. Two diagnostic holes 2 are respectively arranged on two side walls of the black cavity 1, the normal lines of the two diagnostic holes 2 are 180 degrees, and the centers of the diagnostic holes 2, the black cavity 1, the single-energy channel 4, the pinhole array 5, the microchannel plate 6 and the X-ray imaging equipment are all positioned on the same straight line.

The single-energy channel 4 of the embodiment is a Ross filter or a spherical curved crystal and is used for X-ray single-energy gating; the pinhole array 5 is used for imaging; the microchannel plate 6 is used for time resolution; the X-ray imaging apparatus is used for X-ray imaging.

And S2, coating a layer of fluorescent material on the surface of the target ball, and arranging the target ball in the center of the black cavity.

In this embodiment, a layer of silicon fluorescent material is coated on the target ball 3, the center of the target ball 3 is a hydrocarbon solid ball, i.e., a CH solid ball, and the thickness of the silicon fluorescent material coated on the outer layer is 5-10 μm. A target ball 3 coated with a fluorescent material is placed in the center of the black cavity 1.

And S3, injecting laser into the black cavity, and obtaining a fluorescent image of the target ball with single energy on the X-ray imaging device.

Injecting laser from an opening of the black cavity 1, converting the laser into soft X-rays and M-band X-rays on the wall of the black cavity 1, and simultaneously acting the soft X-rays and the M-band X-rays on the surface of the target ball 3; the surface of the target ball 3 is coated with a layer of Si fluorescent material, and due to the threshold characteristic of fluorescence emission, the M-band X-ray in the black cavity 1 induces the characteristic fluorescence of Si, but the soft X-ray cannot induce the fluorescence, so the fluorescence intensity emitted by the target ball 3 is in direct proportion to the intensity of the M-band X-ray; the fluorescence emitted by the target ball 3 is subjected to energy selection by the single energy channel 4, then passes through the pinhole array 5 and the microchannel plate 6, and finally forms a space-time resolution single energy fluorescence image on an X-ray imaging device 7. Because the symmetry of the black cavity M-band X-ray radiation is changed along with time, the time evolution of the symmetry of the M-band X-ray radiation can be obtained by recording fluorescence images at different moments. Referring to fig. 3, a fluorescent image of the target ball at a certain time recorded by the X-ray imaging apparatus in the present embodiment is shown.

And S4, calculating to obtain the symmetry of the M-band X-ray radiation by using the fluorescence image of the target ball.

Obtaining a fluorescence intensity angle distribution f (theta) by using the target ball fluorescence image, and expanding the f (theta) according to Legendre polynomial to obtain:

coefficient of expanding the above formulaThe obtained radiation asymmetry of each order of the M-band X-ray in the black cavity is c₁/c₀，c₂/c₀，c₃/c₀......c_l/c₀In which P is_l(cos θ) is a Legendre polynomial of degree l. Referring to FIG. 4, the fluorescence intensity angle distribution of the fluorescence image of the target sphere is shown, wherein A is the fluorescence intensity angle distribution of the original image, and B is the intensity angle distribution obtained by Legendre polynomial fitting.

Since the intensity of the fluorescence emitted by the target spheres 3 is proportional to the intensity of the M-band X-rays, the intensity angular distribution of the fluorescence image of the target spheres 3 is equivalent to the M-band X-ray radiation symmetry distribution, and thus the M-band X-ray radiation symmetry can be obtained from the intensity angular distribution of the fluorescence image.

In summary, according to the method for measuring the symmetry of the black cavity M-band X-ray radiation provided by the invention, the high-energy M-band X-ray in the black cavity is used for inducing the characteristic fluorescence of the Si material, and further the symmetry distribution of the M-band X-ray radiation can be obtained through the fluorescence image of the target ball; the invention can distinguish the effects of the soft X-ray and the M-band X-ray by utilizing the threshold characteristic of fluorescence emission, obtains the radiation symmetry of the frequency-divided M-band X-ray through the fluorescence image of the target ball, and has important application prospect in indirect drive laser fusion.

The foregoing basic embodiments of the invention and their various further alternatives can be freely combined to form multiple embodiments, all of which are contemplated and claimed herein. In the scheme of the invention, each selection example can be combined with any other basic example and selection example at will.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.