CN111948699A - A compact proton spectroscopy measuring device - Google Patents

Abstract

The invention provides a compact proton energy spectrum measuring device, which solves the problems of low efficiency and the risk of contacting pollutants in the existing proton energy spectrum detection using a stack detector. The device includes a wedge-shaped filter, a scintillator, an imaging lens and a detector that are coaxially arranged in sequence along the proton emission direction; the thickness of the thin edge of the wedge-shaped filter is 0.2mm-2mm, and the thickness of the thick edge is 1.0mm-10mm; the imaging lens adopts The object-side telecentric system; the proton beam is incident on the wedge-shaped filter, filtered by the energy spectrum of the wedge-shaped filter, and then enters the scintillator, which excites visible photons and enters the imaging lens, and the imaging lens images the spatial distribution image of the visible photons to the image of the detector. Enhance the target surface. The energy of the protons passing through different thickness positions of the wedge-shaped filter is different, so the continuous energy spectrum information of the proton can be obtained through the wedge-shaped filter, and the efficient measurement of the proton energy spectrum can be realized.

Description

A compact proton spectroscopy measuring device

technical field

The invention belongs to the field of laser fusion, relates to proton detection technology, and in particular relates to a compact proton energy spectrum measuring device applied to nuclear fusion research.

Background technique

Fusion energy is a kind of non-polluting clean energy, and all countries in the world are competing to invest a lot of manpower and material resources in the research and development of related technologies. However, the conditions for realizing fusion are extremely harsh, and the fuel needs to reach extreme high temperature and high pressure. At present, laser inertial confinement fusion and magnetic confinement fusion are the two most promising technical ways to achieve this condition.

In laser inertial confinement fusion, in order to achieve the "central hot spot" DH (DianHuo) condition of fuel, countries around the world have built or planned large-scale laser-driven devices, such as the NIF device that has been built in the United States, which has 192 high-energy beams Laser, the output energy is 1.8MJ; the LMJ device under construction in France has 240 high-energy lasers and the output energy is 1.8MJ; the KaЛbMep under construction in Russia, the output energy is 2.0MJ.

In recent years, in addition to expanding the scale of laser drive devices, a scheme based on high-energy proton beams to achieve fast DH has also been proposed, that is, when the fusion fuel is compressed to the maximum density, a beam of ultra-short and ultra-intensive laser pulses is focused on the target. On the surface, the extremely high gravitational force punches holes on the critical density surface of the plasma on the surface of the target shot, and presses the critical density surface to the high-density core of the target core. In this process, a large number of Mev energy high-energy proton beams are generated, proton beam It penetrates the critical density surface and injects into the high-density nucleus, so that the temperature of the ions is rapidly heated up and fast DH is achieved. Since the fast DH scheme will greatly reduce the driving laser energy, it has received extensive attention; the high-energy proton beam generated by the ultra-intensive laser-driven thin-film target has also become a research hotspot.

Currently, proton photographic image recording is usually performed with a stack detector, which consists of a stack of radiochromic diaphragms (RCFs) and filters. When the proton beam is irradiated on the RCF stack detector, the high-energy protons move fast and have a long range, and the energy is mainly deposited on the rear RCF layer; while the low-energy protons move slowly and have a short range, and the energy is mainly deposited on the front RCF layer. Proton spectral information is obtained by comparing images recorded by different layers of RC F. This method requires image analysis of different layers of membranes after the experiment, which is inefficient and easy for personnel to be contaminated by radiation. Therefore, there is an urgent need to design a proton detection device that can experimentally measure and study the directionality and energy spectrum of the proton beam generated by the interaction of the ultra-short and ultra-intensive laser pulse with the surface of the target.

SUMMARY OF THE INVENTION

In order to solve the technical problems of low efficiency and the risk of contact with pollutants in the existing proton energy spectrum detection using stack detectors, the present invention provides a compact proton energy spectrum measurement device.

For achieving the above object, the technical scheme provided by the present invention is:

A compact proton energy spectrum measurement device, which is special in that it comprises a wedge-shaped filter, a scintillator, an imaging lens and a detector which are coaxially arranged in sequence along the proton emission direction;

The thickness of the thin side of the wedge-shaped filter is 0.2mm-2mm, and the thickness of the thick side is 1.0mm-10mm;

The imaging lens adopts an object-side telecentric system;

The proton beam is incident on the wedge-shaped filter, and after being spectrally filtered by the wedge-shaped filter, it enters the scintillator, excites visible photons and enters the imaging lens, and the imaging lens images the spatial distribution image of the visible photons to the image intensification target of the detector. face.

Further, the thickness of the thin side of the wedge-shaped filter is 0.4 mm, the thickness of the thick side is 2.0 mm, and the surface size is 40 mm×40 mm.

Further, the object-side numerical aperture NA of the imaging lens is 0.164.

Further, it also includes a sealing window;

The imaging lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens that are coaxially arranged in sequence along the proton emission direction;

The sealing window is arranged between the sixth lens and the seventh lens, and the seventh lens, the eighth lens and the detector are jointly sealed in the atmosphere chamber or the atmosphere bag.

Further, the spherical radius of the front surface of the first lens is -81.65, and the spherical radius of the rear surface is -54.41;

The spherical radius of the front surface of the second lens is 153.46, and the spherical radius of the rear surface is -150.34;

The spherical radius of the front surface of the third lens is 59.16, and the quadratic curve coefficient k, second-order coefficient α ₁ , fourth-order coefficient α ₂ , sixth-order coefficient α ₃ of the front surface are 0.5313, 7.983×10 ⁻⁵ , − 3.125×10 ^-7 , -1.996×10 ^-11 ;

The spherical radius of the front surface of the fourth lens is -153.46, and the spherical radius of the rear surface is 52.24;

The spherical radius of the front surface of the fifth lens is 153.46, and the spherical radius of the rear surface is -150.34;

The spherical radius of the front surface of the sixth lens is 153.46, and the spherical radius of the rear surface is -150.34;

The spherical radius of the front surface of the seventh lens is 31.9, and the spherical radius of the rear surface is 30.57;

The spherical radius of the front surface of the eighth lens is -57.15, and the spherical radius of the rear surface is 141.88.

Further, the thicknesses of the scintillator, the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the sealing window, the seventh lens, and the eighth lens are respectively 2.0 mm and 13.1 mm. mm, 12.3mm, 13.5mm, 6.20mm, 12.3mm, 12.3mm, 12.0mm, 12.1mm, 3.2mm.

Further, the distance from the rear surface of the scintillator to the front surface of the first lens is 51.78mm;

The distance from the rear surface of the first lens to the front surface of the second lens is 146.22 mm;

The distance from the rear surface of the second lens to the front surface of the third lens is 0.63 mm;

The distance from the rear surface of the third lens to the front surface of the fourth lens is 2.83mm;

The distance from the rear surface of the fourth lens to the front surface of the fifth lens is 47.83mm;

The distance from the rear surface of the fifth lens to the front surface of the sixth lens is 24.19 mm;

The distance from the rear surface of the sixth lens to the front surface of the sealing window is 23.40mm;

The distance from the rear surface of the sealing window to the front surface of the seventh lens is 12.37 mm;

The distance from the rear surface of the seventh lens to the front surface of the eighth lens is 8.5mm;

The distance from the rear surface of the eighth lens to the image enhancement target surface is 9.91 mm.

Further, the diameters of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the sealing window, the seventh lens, the eighth lens, and the image enhancement target surface are respectively 70mm, 70mm, 64mm, 64mm, 70mm, 70mm, 100mm, 44mm, 40mm, 28mm.

Further, the refractive index nd of the first lens is 1.58, and the dispersion vd is 41.3;

The refractive index nd of the second lens is 1.50, and the dispersion vd is 81.6;

The refractive index nd of the third lens is 1.50, and the dispersion vd is 81.6;

The refractive index nd of the fourth lens is 1.58, and the dispersion vd is 41.3;

The refractive index nd of the fifth lens is 1.50, and the dispersion vd is 81.6;

The refractive index nd of the sixth lens is 1.50, and the dispersion vd is 81.6;

The refractive index nd of the sealing window is 1.46, and the dispersion vd is 67.8;

The refractive index nd of the seventh lens is 1.58, and the dispersion vd is 41.3;

The refractive index nd of the eighth lens is 1.58, and the dispersion vd is 41.3.

Further, the material of the scintillator is BC422;

The detector is an ICCD.

Compared with the prior art, the advantages of the present invention are:

1. The measuring device of the present invention uses a wedge-shaped filter to filter the energy spectrum of the proton beam, and is incident on the scintillator to excite visible photons, and then the spatial distribution information of the visible photons is imaged on the image enhancement target surface of the detector by the imaging lens, Since the proton energy transmitted through different thickness positions of the wedge-shaped filter is different, the continuous energy spectrum information of the proton can be obtained through the wedge-shaped filter, and the proton energy spectrum measurement can be realized; The imaging process has high fidelity, so that the solid angle of light received at each point of the scintillator is consistent, and the direction of the collected beam is consistent.

2. The object-side numerical aperture NA of the imaging lens of the present invention is 0.164, so that the solid angle of light received at each point of the scintillator and the direction of the collected beam are consistent, and the inconsistency of the collection efficiency of each point on the object surface (scintillator) is: 2%.

3. The imaging lens of the present invention can operate stably for a long time in the fusion radiation environment, and the collection rate of the luminescence of each point on the large-area scintillator is consistent, and will not bring distortion to the measurement of the luminescence distribution on the scintillator, thereby improving the accuracy of the measurement sex.

4. Due to the small distance between the detector and the imaging lens, if the sealing window is set between the detector and the imaging lens, the entire optical path needs to be enlarged in the same proportion, so that there is enough space between the lens and the detector to set the seal. Therefore, in the present invention, the sealing window is arranged between the sixth lens and the seventh lens, so that the detector, the seventh lens and the eighth lens can be jointly sealed in the atmospheric environment. While realizing the sealing of the detector, the miniaturization of the measuring device can also be realized.

5. The measuring device of the present invention can also be used in the measurement of fusion fuel compression symmetry, fuel surface density and the like.

Description of drawings

Fig. 1 is the structural representation of the compact proton energy spectrum measuring device of the present invention;

Among them, the reference numerals are as follows:

1- wedge filter, 2- scintillator, 3- first lens, 4- second lens, 5- third lens, 6- fourth lens, 7- fifth lens, 8- sixth lens, 9- seal Window, 10-seventh lens, 11-eighth lens, 12-image enhancement target surface.

Detailed ways

The content of the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

As shown in Figure 1, a compact proton spectroscopy measurement device based on a wedge-shaped filter and a scintillator includes a wedge-shaped filter 1, a scintillator 2, an imaging lens and a detector that are coaxially arranged in sequence along the proton emission direction; The beam enters a large-area wedge-shaped filter 1, and after the energy spectrum filtering of the wedge-shaped filter 1, it enters the scintillator 2 to excite visible photons, and then the imaging lens images the spatial distribution information (image) of the excited visible photons to the detector. on the image enhancement target surface 12.

The thickness of the thin side of the wedge-shaped filter 1 is 0.2mm to 2mm, the thickness of the thick side is 1.0mm to 10mm, and the thickness of the thin side is less than the thickness of the thick side. In this embodiment, the thickness of the thin side is 0.4mm, and the thickness of the thick side is 2.0 mm. mm, the surface shape of the wedge filter 1 is rectangular, and the size specification is 40mm×40mm; the proton energy transmitted by different thickness filter positions in the wedge filter 1 is different, so the continuous energy spectrum information of the proton can be obtained through the wedge filter 1 , to achieve proton spectroscopy measurements.

The protons transmitted from different positions of the wedge-shaped filter 1 are incident on the scintillator 2, the energy is stored in the scintillator 2, and visible photons (thermoluminescence) are emitted. The material of the scintillator 2 is BC422.

The imaging lens collects the visible photons (thermoluminescence) emitted by the scintillator 2, and images the photon spatial distribution image on the image intensification target surface 12 of the detector. After the image is enhanced, it is recorded by the subsequent CCD camera.

Since the scintillator 2 emits light with a large solid angle, it is usually difficult for the imaging lens to collect all the light emitted by the scintillator 2 . However, it should be ensured that the light-receiving rate of the imaging lens for each point of the scintillator 2 must be consistent, so that the light intensity distribution of the image surface can truly reflect the photon space distribution of the object surface of the scintillator 2 . In order to ensure the consistency of the light collection rate, the imaging lens of this embodiment adopts an object-side telecentric optical path, so that the solid angle of light-receiving at each point of the scintillator 2 and the direction of the collected beam are the same, and the object-side numerical aperture of the imaging lens is NA: 0.164 The light half angle is 9.5°), and the inconsistency of the collection efficiency of each point on the object surface (40mm×40mm) is 2%.

According to the luminescence spectrum (350nm-450nm) characteristics of scintillator 2, the imaging lens should be made of ultraviolet high-transmittance optical glass material, and in order to improve the light transmission efficiency of the imaging lens, the surface of the optical components of the imaging lens should be coated with UV anti-reflection coating, but Due to the lack of UV high-transmittance optical glass materials, the cost is high. Therefore, the imaging lens of this embodiment adopts the structure as shown in FIG. 1, and the imaging lens includes a first lens 3, a second lens 4, a third lens 5, a fourth lens 6, a fifth lens 7, a first lens 3, a second lens 4, a third lens 5, a fourth lens 6, a fifth lens 7, The sixth lens 8 , the seventh lens 10 and the eighth lens 11 . When the measuring device is used, it is located in a vacuum environment, and ordinary detectors cannot work in a vacuum. Therefore, the detector can be a vacuum-sealed detector; the wedge-shaped filter 1, scintillator 2 and imaging lens can also be located in a vacuum environment. The detector is located outside the vacuum environment, but since the distance between the detector and the imaging lens is small, if a sealing window is set between the detector and the imaging lens, the entire lens needs to be enlarged in the same proportion, which makes the measuring device larger. In practical applications, an atmospheric chamber/package is often designed in a vacuum, and the detector is placed in it. The chamber/package communicates with the atmosphere through two airtight air pipes, one for intake and one for exhaust. The detector inside is gas-cooled (or liquid-cooled by heat transfer). Therefore, it is necessary to set a vacuum sealing window between the imaging lens and the detector, which can allow light to pass through and achieve sealing at the same time. In this embodiment, the sealing window 9 is set on the sixth lens and the seventh lens, and the seventh lens 10 and the eighth lens are The lenses 11 are jointly arranged in the air chamber/package, so that the back focal distance is small, and the miniaturization of the measurement device can also be realized while the detector is sealed.

In order to improve the spatial resolution of the imaging lens, the third lens 5 of the imaging lens adopts an aspheric surface, which greatly reduces the chromatic spherical aberration of the system. The spatial resolution of the imaging lens to the scintillator 2 is less than 30 microns.

The parameters of the optical elements in the compact proton spectroscopy measuring device of this embodiment are shown in Table 1 below;

Table 1 Parameters of optical components in the compact proton spectrometry device

The coordinate data in the table adopts the right-handed coordinate system as shown in Figure 1, the horizontal right is +Z axis, the vertical paper is +X axis inward, and the upward is +Y axis. The symbol of the spherical radius of the lens is defined as follows: if the center of the sphere is on the left side of the sphere, the radius is negative, and if the center of the sphere is on the right side of the sphere, the radius is positive. The third lens 5 is an even-order aspheric surface, and its surface formula is shown in formula (1):

In the formula: z is the reflector sag; c is the reciprocal of the spherical radius; k is the quadratic curve coefficient; α ₁ ～α ₃ : even-order aspheric coefficients; r is the radial variable.

It can be seen from Table 1 that the imaging lens has a large object-side field of view (40mm×40mm). By using an aspherical lens, the structure of the lens is simple and compact (total length is 425mm), and the optical system can obtain a higher object-side field of view. Spatial resolution capability (less than 60 microns); the optical system adopts a separate structure, and there is no glue surface to prevent the optical glue from being denatured by radiation and affecting the light transmission performance of the system.

The above only describes the preferred embodiments of the present invention, and does not limit the technical solutions of the present invention to this. Any known deformations made by those skilled in the art on the basis of the main technical concept of the present invention belong to the protection of the present invention. technical category.

Claims (10)

1. A compact proton energy spectrum measuring device, characterized in that: the device comprises a wedge-shaped filter disc (1), a scintillator (2), an imaging lens and a detector which are coaxially arranged in sequence along the proton emergent direction;

the thickness of the thin edge of the wedge-shaped filter disc (1) is 0.2 mm-2 mm, and the thickness of the thick edge is 1.0 mm-10 mm;

the imaging lens adopts an object space telecentric system;

proton beams enter the wedge-shaped filter disc (1), enter the scintillator (2) after being subjected to energy spectrum filtering by the wedge-shaped filter disc (1), excite visible photons and enter the imaging lens, and the imaging lens images a space distribution image of the visible photons onto an image enhancement target surface (12) of the detector.

2. The compact proton energy spectrum measuring device according to claim 1, wherein: the thickness of the thin edge of the wedge-shaped filter disc (1) is 0.4mm, the thickness of the thick edge is 2.0mm, and the surface size is 40mm multiplied by 40 mm.

3. The compact proton energy spectrum measuring device according to claim 2, wherein: and the object-side numerical aperture NA of the imaging lens is 0.164.

4. The compact proton energy spectrum measuring device according to any one of claims 1 to 3, wherein: also comprises a sealing window (9);

the imaging lens comprises a first lens (3), a second lens (4), a third lens (5), a fourth lens (6), a fifth lens (7), a sixth lens (8), a seventh lens (10) and an eighth lens (11) which are coaxially arranged in sequence along the proton emergent direction;

the sealing window (9) is arranged between the sixth lens (8) and the seventh lens (10), the eighth lens (11) and the detector are sealed in an atmosphere cabin or an atmosphere bag together.

5. The compact proton energy spectrum measuring device according to claim 4, wherein: the spherical radius of the front surface of the first lens (3) is-81.65, and the spherical radius of the rear surface of the first lens is-54.41;

the spherical radius of the front surface of the second lens (4) is 153.46, and the spherical radius of the rear surface of the second lens is-150.34;

the spherical radius of the front surface of the third lens (5) is 59.16, and the conic coefficient k and the second-order coefficient alpha of the front surface₁Fourth order coefficient alpha₂Coefficient of order six alpha₃0.5313, 7.983 x 10 respectively^-5、-3.125×10^-7、-1.996×10^-11；

The spherical radius of the front surface of the fourth lens (6) is-153.46, and the spherical radius of the rear surface of the fourth lens is 52.24;

the spherical radius of the front surface of the fifth lens (7) is 153.46, and the spherical radius of the rear surface of the fifth lens is-150.34;

the spherical radius of the front surface of the sixth lens (8) is 153.46, and the spherical radius of the rear surface of the sixth lens is-150.34;

the spherical radius of the front surface of the seventh lens (10) is 31.9, and the spherical radius of the rear surface of the seventh lens is 30.57;

the spherical radius of the front surface of the eighth lens (11) is-57.15, and the spherical radius of the rear surface of the eighth lens is 141.88.

6. The compact proton energy spectrum measuring device according to claim 5, wherein: the thicknesses of the scintillator (2), the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), the sixth lens (8), the sealing window (9), the seventh lens (10) and the eighth lens (11) are respectively 2.0mm, 13.1mm, 12.3mm, 13.5mm, 6.20mm, 12.3mm, 12.0mm, 12.1mm and 3.2 mm.

7. The compact proton energy spectrum measuring device of claim 6, wherein: the distance from the rear surface of the scintillator (2) to the front surface of the first lens (3) is 51.78 mm;

the distance from the rear surface of the first lens (3) to the front surface of the second lens (4) is 146.22 mm;

the distance from the rear surface of the second lens (4) to the front surface of the third lens (5) is 0.63 mm;

the distance from the rear surface of the third lens (5) to the front surface of the fourth lens (6) is 2.83 mm;

the distance from the rear surface of the fourth lens (6) to the front surface of the fifth lens (7) is 47.83 mm;

the distance from the rear surface of the fifth lens (7) to the front surface of the sixth lens (8) is 24.19 mm;

the distance from the rear surface of the sixth lens (8) to the front surface of the sealing window (9) is 23.40 mm;

the distance from the rear surface of the sealing window (9) to the front surface of the seventh lens (10) is 12.37 mm;

the distance from the rear surface of the seventh lens (10) to the front surface of the eighth lens (11) is 8.5 mm;

the distance from the rear surface of the eighth lens (11) to the image enhancement target surface (12) is 9.91 mm.

8. The compact proton energy spectrum measuring device of claim 7, wherein: the diameters of the first lens (3), the second lens (4), the third lens (5), the fourth lens (6), the fifth lens (7), the sixth lens (8), the sealing window (9), the seventh lens (10), the eighth lens (11) and the image enhancement target surface (12) are respectively 70mm, 64mm, 70mm, 100mm, 44mm, 40mm and 28 mm.

9. The compact proton energy spectrum measuring device of claim 8, wherein: the refractive index nd of the first lens (3) is 1.58, and the dispersion vd is 41.3;

the refractive index nd of the second lens (4) is 1.50, and the dispersion vd is 81.6;

the refractive index nd of the third lens (5) is 1.50, and the dispersion vd is 81.6;

the refractive index nd of the fourth lens (6) is 1.58, and the dispersion vd is 41.3;

the refractive index nd of the fifth lens (7) is 1.50, and the dispersion vd is 81.6;

the refractive index nd of the sixth lens (8) is 1.50, and the dispersion vd is 81.6;

the refractive index nd of the sealing window (9) is 1.46, and the dispersion vd is 67.8;

the refractive index nd of the seventh lens (10) is 1.58, and the dispersion vd is 41.3;

the refractive index nd of the eighth lens (11) is 1.58, and the dispersion vd is 41.3.

10. The compact proton energy spectrum measuring device according to claim 1, wherein: the material of the scintillator (2) is BC 422;

the detector is an ICCD.

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