RU2778245C1 - Box for experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell - Google Patents

Abstract

FIELD: experiments conducting.

SUBSTANCE: invention relates to a box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell. The box is a metal structure with a spherical cavity inside, covered with a layer of gold, in the center of which there is a shell held on a capillary for the admission of hydrogen isotopes. A capillary was inserted into the box to let in helium through the appropriate hole. Four windows are made in the metal structure, two of which are used to observe the shell, and one is used to induce infrared radiation through optically transparent windows (external radiation induction scheme). The box provides for the implementation of three additional schemes for introducing infrared radiation. In a particular case, associated with varying the output parameters for the experiment, the box for conducting experiments on infrared heating of the cryogenic layer of hydrogen isotopes in a spherical shell has variations in the diameter of the inner spherical cavity from 10 to 25 mm with a step of 5 mm. To connect the halves of the structure into a single box, through holes are made in one of the halves, and in the counterpart there are threaded blind holes with a diameter of M2. The tightness of the assembly is ensured by the use of cryogenic glue.

EFFECT: increase in the experimental possibilities of the box for the implementation of various schemes for introducing infrared radiation into the box, while simplifying the design and reducing its weight and size parameters.

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Description

The present invention relates to the field of laser thermonuclear fusion (LTF) and cryogenics and can be mainly used to obtain an equal-thickness cryogenic layer of hydrogen isotopes in a spherical shell for subsequent experiments on the compression of a thermonuclear target near its ignition threshold.

Known Boxing for experiments on infrared heating of the cryogenic layer of hydrogen isotopes in a spherical shell [E.I. Osetrov, V.M. Izgorodin, E.Yu. Solomatina, et al. Experiments on leveling the cryogenic layer of deuterium in thickness by IR radiation. // V International Conference "Laser, Plasma Research and Technologies" LaPlaz-2019: Collection of scientific papers. Part 2. M.: NRNU MEPhI, 2619. - 388 p.s. 362-363].

The known device is a box with a spherical cavity inside, the so-called alignment sphere. In the center of the sphere there is a shell filled with hydrogen isogones through a capillary. The box has four windows for observing the layer, one of which is used to introduce infrared radiation. Boxing windows are made of lavsan.

In the known device, the source of infrared radiation is located outside the cryostat, the radiation passes through the windows of the cryostat, the cryogenic screen and the windows of the box (diagram of external radiation institution).

The disadvantages of this device are the inability to carry out experiments on the formation of a cryolayer with a different establishment of infrared radiation.

Known Boxing for experiments on infrared heating of the cryogenic layer of hydrogen isotopes in a spherical shell [D.N. Bittner, G.W. Collins, and J.D. sater. Generating Low Temperature Layers with IR Heating / Preprint, UCRL-JC-143446. Lawrence Livermore National Laboratory, 01/31/2003].

The known device is a box made of aluminum with an inner sphere with a diameter of 23 mm, on the surface of which a layer of gold is deposited. In the center of the sphere there is a shell filled with hydrogen isotopes through a capillary. The box has four windows for observing the cryolayer.

In this box, the optical fiber is inserted inside the alignment sphere to inject infrared radiation directly into the cavity of the box (scheme of internal radiation induction).

The disadvantages of this device is the impossibility to conduct experiments on the formation of a cryolayer with a different institution of infrared radiation, in addition, the complexity and large dimensions of the structure with a large number of constituent components can be of fundamental importance when conducting experiments on LTS.

The set of features closest to the set of essential features of the invention is inherent in the well-known box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes and a spherical shell [D.N. Bittner at al. Forming Uniform HD Layers in Shells Using Infrared Radiation / UCRL-JC-131371, PREPRINT, Lawrence Livermore National Laboratory, 10/12/1998].

The known device is a box with an inner sphere of 25 mm, in the center of which is a shell filled with hydrogen isotopes through a capillary. The inner sphere is made of aluminum (OFHC copper) and plated with gold for greater reflection of infrared radiation. The box has four holes with a diameter of 4 mm, one pair of holes is used to introduce infrared radiation into the box through the windows of the cryostat. The second pair of holes is used to observe the cryolayer (microscope with camera and illumination).

In contrast to the design being developed, the openings of the box are covered with sapphire lenses.

The disadvantages of this device are the large dimensions of the box, the laborious process of assembling the box and preparing for the experiment, the laborious implementation of the method of introducing infrared radiation without hitting the shell, the impossibility of introducing infrared radiation directly into the box, bypassing the cryostat and box windows. The known device does not allow to carry out experiments on the formation of a cryolayer with a different institution of infrared radiation. Also, the device does not allow achieving the minimum size of the box with a minimum number of components, which can be of fundamental importance when conducting experiments on LTS.

The task to be solved by the claimed invention is the universalization of the box design, aimed at the possibility of forming an equal-thickness cryolayer of hydrogen isotopes with the implementation of various schemes for introducing infrared radiation into the box cavity and its subsequent use in experiments on laser installations.

The technical result is an increase in the experimental capabilities of the box in terms of implementing various schemes for introducing infrared radiation into the box, while simplifying the design and reducing its weight and size parameters.

The technical result of the invention is ensured by the fact that the box for conducting experiments on infrared heating of the cryogenic layer of hydrogen isotopes in a spherical shell is a metal structure with a spherical cavity coated with a layer of gold inside, in the center of which there is a shell held on a capillary for puffing hydrogen isotopes; a capillary was inserted into the box to inject helium through the corresponding hole: four windows were made in the metal structure, two of which are used to observe the shell, and one is used to introduce infrared radiation through optically transparent windows (external radiation induction scheme). According to the invention, the box provides for the implementation of three additional schemes for inducing infrared radiation, for which the radiation initiation window is made larger relative to the observation windows, which are made of the minimum size for the possibility of observing the shell, while an additional hole for inducing infrared radiation is made above the radiation initiation window. radiation into a spherical cavity without a direct hit on the shell, as a means for inducing radiation, an optical fiber is used, which is led directly into the box (internal radiation induction scheme), or radiation is introduced through optically transparent windows (external radiation induction scheme): the window material is used lavsan film.

In a particular case, associated with varying the output parameters for the experiment, the box for conducting experiments on infrared heating of the cryogenic layer of hydrogen isotopes in a spherical shell has variations in the diameter of the inner spherical cavity from 10 to 25 mm with a step of 5 mm.

To connect the halves of the structure into a single box, through holes are made in one of the halves, and in the counterpart there are threaded blind holes with a diameter of M2, the tightness of the assembly is ensured by the use of cryogenic glue.

The location of the additional hole for introducing infrared radiation on the surface of the box was chosen taking into account the calculation of the propagation of the infrared beam in the alignment sphere. The result of this calculation was the conclusion about the need to direct the incoming light cone to where there are no windows (to avoid beam energy losses), preferably upwards (where the box surface is colder due to the temperature gradient), at the maximum possible angle of inclination to the horizontal plane (for more diffuse reflections). ), exactly in the vertical plane of symmetry of the alignment sphere (for maximally equal irradiation of the side poles of the shell).

In addition, in order to understand the temperature distribution in the box and shell, a thermal calculation of the model of the experimental box was carried out, as close as possible in geometry and conditions to real experiments. In the calculations, the temperature distribution in the experimental box and the cryogenic layer was analyzed under various conditions: the scheme of external insertion of a collimated beam of infrared radiation with a diameter of 8 mm and 2.5 mm directed strictly in the horizontal plane (on the shell) and at an angle of 17° to the horizontal (according to preliminary theoretical calculations). It was concluded that in order to obtain a cryogenic layer uniform in thickness, it is necessary to direct infrared radiation at an angle, avoiding direct contact with the shell, on the inner surface of the sphere of the matte alignment sphere to obtain uniformly scattered diffuse radiation (implemented for all four schemes for introducing infrared radiation, for this one of the windows is made of a larger diameter and an additional hole is made), as well as to avoid hitting a direct radiation beam on the box wall by creating a collimated beam with a diameter of less than 2.5 mm for a scheme with external radiation induction, or to lead the radiation inside the experimental box.

Introducing radiation through an additional hole makes it possible to use the vacated pair of windows along one axis for diagnosing the layer or for organizing optical observation of the cryolayer in the shell along two mutually perpendicular axes.

The thermal calculation of the experimental boxes showed that to achieve an isothermal thermal environment, the alignment sphere diameter of 15 mm is sufficient, which makes it possible to significantly reduce the dimensions of the box compared to foreign analogues and thereby increase the cooling rate to the required temperatures of the entire box structure. In the course of experiments on the formation of a cryolayer, it was found that the diameter of the alignment sphere does not significantly affect the thickness variation of the resulting layer, and a cryolayer of the required quality can be obtained in a sphere of a smaller diameter.

The use of lavsan film glued on cryogenic glue as a material for sealing the windows of the box makes it possible to simplify the design of the box, reduce the number of assembly components without losing the quality characteristics of the box.

The essence of the invention is illustrated by the drawings shown in Fig. 1-8.

In FIG. Figure 1 shows a box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell, installed on the table of the second stage of the cryostat, left view, where:

1 - left half of the structure;

2 - right half of the structure;

3 - alignment sphere (spherical cavity);

4 - spherical shell;

8 - hole for entering a capillary for helium puffing;

10 - boxing window for the introduction of infrared radiation;

11 - hole for input of infrared radiation;

14 - table of the second stage of the cryostat.

In FIG. Figure 2 shows a box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell, mounted on a table of the second stage of the cryostat, front view, where:

5 - capillary for the inlet of hydrogen isotopes;

6 - hole for entering the capillary for hydrogen isotopes;

7 - capillary for helium inlet;

8 - hole for entering a capillary for helium puffing;

9 - box windows for observation;

10 - boxing window for the introduction of infrared radiation;

11 - hole for input of infrared radiation;

12 - films on the windows of the box;

13 - threaded connections.

In FIG. Figure 3 shows a box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell, installed on the table of the second stage of the cryostat, right view, where:

6 - hole for entering the capillary for hydrogen isotopes;

12 - films on the windows of the box.

In FIG. 4 shows an external scheme for introducing infrared radiation into the alignment sphere through the box window, where:

2 - right half of the structure;

3 - alignment sphere (spherical cavity);

4 - spherical shell;

5 - capillary for the inlet of hydrogen isotopes;

9 - box windows for observation:

10 - boxing window for the introduction of infrared radiation;

11 - hole for input of infrared radiation;

14 - table in the throne of the cryostat stage;

15 - conditional image of infrared radiation;

16 - optical fiber, conducting infrared radiation;

17 - body of the cryostat;

18 - cryogenic screen.

In FIG. 5 shows a diagram of the internal introduction of infrared radiation into the alignment sphere through the box window, where:

15 - conditional image of infrared radiation;

16 - optical fiber that conducts infrared radiation.

In FIG. 6 shows a diagram of the external introduction of infrared radiation into the alignment sphere through an additional opening of the box, where;

15 - conditional image of infrared radiation;

16 - optical fiber that conducts infrared radiation.

In FIG. 7 shows a diagram of the internal introduction of infrared radiation into the alignment sphere through an additional opening of the box, where:

15 - conditional image of infrared radiation;

16 - optical fiber that conducts infrared radiation.

In FIG. 8 shows the process of formation of a cryogenic layer of ice in a shell with the final result of the experiment on the formation of a cryogenic layer of deuterium, with a thickness difference of less than 1%, where;

5 - spherical shell.

In the box structure developed in accordance with FIG. 1-3. it turned out to implement various schemes for introducing infrared radiation into the alignment sphere. In FIG. Figures 4-7 show diagrams for introducing infrared radiation into the alignment sphere. Each of these schemes was tested experimentally and satisfactory results were obtained for the alignment of the cryolayer of hydrogen isotopes by infrared heating, one of which is shown in Fig. eight.

The box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell is a metal structure of two symmetrical halves 1 and 2, made of M1 grade copper with recesses on the inner surface in the form of hemispheres, which, when assembled, represent a spherical cavity - an alignment sphere 3. which should provide uniform thermal heating of the cryogenic layer as a result of multiple reflections of infrared radiation. Each hemisphere is coated with gold (~1 µm thick) for better reflection of infrared radiation. In the center of the alignment sphere there is a spherical shell 4 (with a diameter of 1.3 to 2 mm and a wall thickness of 10 to 30 µm) held on a capillary for the inlet of hydrogen isotopes 5 (a composite capillary with a transitional diameter of 20 µm to 1 mm), which inserted into a hole in box 6; in the implemented invention, its diameter is ∅1.1 mm. A helium capillary 7 (1 mm in diameter made of steel 12Kh18N10T) was also inserted into the box through the corresponding hole 8; in the implemented invention, its diameter is ∅1.1 mm.

Windows 9 are made in the box to observe the behavior of the cryolayer in the shell, in the implemented invention their diameter is ∅2 mm, the window 10 for inputting infrared radiation is larger and in the implemented invention is ∅3 mm. Also on one of the sides of the box there is an additional hole 11 for inputting infrared radiation. Windows 9, 10 and an additional hole 11 are sealed with a film 12 made of lavsan with a thickness of 2.5 microns. To connect the halves of the structure into a single box, threaded connections 13 are made in the structure.

The box is assembled in 3 stages: shell 4 and hydrogen isotope capillary 5 are assembled; structure halves 1 and 2 are assembled with shell 4 inside; the assembled box is installed in the cryostat on the second stage stage 14.

The main task during assembly is to ensure the tightness of the box and capillaries for the inlet of working gases (helium, hydrogen isotopes), taking into account their use at cryogenic temperatures. In this case, the ease of installation of the box and the reliability of its connection should also be ensured, taking into account the small size of the experimental assemblies.

The introduction of infrared radiation 15 is carried out both according to the scheme of external introduction of the radiation beam through the box window (Fig. 4, Fig. 6), and for the introduction of fiber 16 inside the box (Fig. 5, Fig. 7).

The box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell is a system of isolated gas volumes with different pressures. The spherical shell 4 is fixed in a metal structure of two halves 1 and 2, which is installed in the working area of the cryostat 17, which is pumped out to a high vacuum of up to 10 ^-8 mbar. The metal structure acts as a container with good heat transfer properties, helium is filled into the spherical cavity 3 through the glued capillary 7 at a pressure of 0.1 mbar, which acts as a heat exchange basin to equalize the temperature of the surface of the spherical shell 4. The shell 4, in turn, through the capillary 5 is filled with hydrogen isotopes in the gas phase up to pressures of the order of 1 bar. The main criterion for a successful experiment is the complete tightness of the assembly of halves of structure 1 and 2 and, accordingly, the absence of helium leaks from the box into the volume of cryostat 17 and the absence of hydrogen isotopes from shell 4 into spherical cavity 3 or into the volume of cryostat 17 during the experiment.

Experiments to obtain a cryogenic layer of hydrogen isotopes are carried out in several stages:

1) Installation of cryoscreen 18 and cryostat body 17.

2) Pumping out the working volume of the cryostat and systems for puffing working gases (helium, hydrogen isotopes) with the help of forevacuum and turbomolecular pumps up to 10 ^-4 mbar.

3) Cooling of the experimental assembly to 20 K.

4) Inlet of helium heat exchange gas into spherical cavity 3 (up to 0.1 bar).

5) Inlet of hydrogen isotopes into spherical shell 4 (from 0.3 to 1 bar).

6) Cooling the assembly to the triple point temperature, dosing the amount of liquid in the shell to the required level.

7) Lowering the temperature with the given speed parameters until the complete transformation of the liquid phase into a solid one.

8) Redistribution of ice in the shell 4 using infrared heating.

9) Diagnostics of the resulting layer, calculation of the parameters of thickness variation.

The process of formation of a cryogenic layer of ice in the shell 4 occurs in accordance with Fig. eight.

To implement the infrared alignment method, it is necessary to introduce infrared radiation 13 with a wavelength corresponding to the absorption peak of the cryolayer substance into the spherical cavity 3 (any of the proposed options shown in Fig. 4-7), as a result of which the cryolayer of hydrogen isotopes begins to absorb infrared radiation and heats up. In this case, the area with a thick layer of ice becomes more heated, and with a thin layer less heated, as a result of which the substance is redistributed and the layer is equalized in thickness.

Alignment sphere 3 should ensure uniform thermal heating of the cryogenic layer as a result of multiple reflections of infrared radiation 15. For better reflection of infrared radiation, each hemisphere is coated with gold (~1 μm thick).

To equalize the cryogenic concentration of deuterium, a mid-infrared laser with a central wavelength of 3.6 μm (deuterium absorption peak) and an output under the optical fiber 16 is used. , which allows you to direct the radiation at different angles, limited only by the aperture of the viewing windows of the box, the cryoscreen and the optical glass of the cryostat. For the scheme of internal insertion (Fig. 5, 7), the optical fiber 16 is inserted into the cavity of the cryostat through the hole 11 and hermetically sealed.

The result of one of the experiments on the formation of a cryogenic layer of deuterium is shown in Fig. 8. The experiment was carried out in a box with an internal alignment sphere 3 with a diameter of 10 mm and gold sputtering. The thickness variation of the cryolayer was 0.5% with an average cryolayer thickness of 208 μm.

A series of experiments on obtaining an equal-thickness cryolayer of hydrogen isotopes in a shell and the results obtained that meet the specified requirements of the layer parameters allow us to conclude that the technical result has been achieved, namely, the box design implements the possibility of using various schemes for introducing infrared radiation into the box with a decrease in its weight and size parameters and simplification of the box design.

Claims (4)

1. A box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell is a metal structure with a spherical cavity coated with a layer of gold inside, in the center of which there is a shell held on a capillary for puffing hydrogen isotopes; a capillary was inserted into the box to let in helium through the corresponding hole; four windows are made in the metal structure, two of which are used to observe the shell, and one is used to introduce infrared radiation through optically transparent windows; characterized in that the box provides for the implementation of three additional schemes for initiating infrared radiation, for which the radiation initiation window is made larger relative to the observation windows, which are made of the minimum size for the possibility of observing the shell, while an additional hole is made above the radiation initiation window for introduction of infrared radiation into a spherical cavity without direct contact with the shell, as a means for introducing radiation, an optical fiber is used, which is brought directly into the box, or radiation is introduced through optically transparent windows: lavsan film is used as the window material. 2. A box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell according to claim 1, characterized in that the box design has variations in the diameter of the inner spherical cavity from 10 to 25 mm with a step of 5 mm. 3. A box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell according to claim 1, characterized in that for connecting the halves of the structure into a single box, through holes are made in one of the halves, and in the counterpart there are threaded blind holes with a diameter of M2 . 4. Box for conducting experiments on infrared heating of a cryogenic layer of hydrogen isotopes in a spherical shell according to claim 1, characterized in that the tightness of the assembly is ensured by the use of cryogenic glue.

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