JPH0386215A - Metal vapor generator - Google Patents

Abstract

PURPOSE:To drastically improve efficiency in vaporizing raw metal by irradiating the plural bodies impregnated with molten metal alternately with the electron beam emitted from an electron beam generator. CONSTITUTION:A vaporizing crucible 12 contg. raw metal 13 and an electron beam generator 14 for emitting an electron beam for heating and vaporizing the raw metal 13 are placed in a vacuum vessel 11. Plural porous bodies 21 and 22 to be impregnated with the molten metal are set in the crucible 12, and the bodies 21 and 22 are alternately irradiated with the electron beam emitted from the generator 14. Consequently, the amt. of the metal to be vaporized is stably secured, and efficiency in vaporizing raw metal is improved.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a metal vapor generator applied to an isotope separation device, and particularly relates to a metal vapor generator that efficiently evaporates metal raw materials. .

(Prior Art) A metal atom isotope separation apparatus using a laser method has a very high isotope separation efficiency and is superior to conventional gas diffusion methods, centrifugation methods, and the like.

For this reason, isotope separation equipment that uses the atomic laser method is
There is no need to repeat the same separation process in a multi-stage cascade method until a specific isotope reaches a predetermined concentration level, and the entire isotope separation device can be made smaller and more compact.
Excellent economy.

Isotope separation equipment that uses this laser method incorporates a metal vapor generator that generates metal vapor in order to perform isotope separation, and this metal vapor generator can efficiently evaporate metal raw materials. is known to improve the separation efficiency of isotope separation devices.

A conventional metal vapor generator includes an evaporation crucible containing a metal raw material in a vacuum container and an electron gun that heats, melts, and evaporates the metal raw material contained in the evaporation crucible. The emitted electron beam was irradiated onto the metal raw material, heating it, melting it, and vaporizing it.

(Problems to be Solved by the Invention) In conventional metal vapor generators, the metal raw material contained in the evaporation crucible is heated and melted by the electron beam emitted from the electron gun. When heated and melted in the crucible, convection of the molten metal occurs,
Due to this convection, the molten metal heated to a high temperature is cooled on the side wall of the evaporation crucible, so the heating by the electron beam does not effectively evaporate the metal raw material, and there is a risk that the evaporation efficiency of the metal raw material may deteriorate. .

There is a large difference in the evaporation efficiency of the metal raw material, for example, about 10 times, between when convection is generated in the evaporation crucible and when it is not, and the generation of convection has been a cause of deteriorating the evaporation efficiency of the metal raw material.

The present invention has been made in consideration of the above-mentioned circumstances, and generates metal vapor that greatly improves the evaporation efficiency of metal raw materials by alternately irradiating a porous body impregnated with molten metal with an electron beam. The purpose is to provide equipment.

Another object of the present invention is to provide a metal vapor generator that can effectively prevent fluctuations in the amount of evaporation of molten metal and stably generate metal vapor.

[Structure of the invention]

(Means for Solving the Problems) In order to solve the technical problems of the prior art, the metal vapor generator according to the present invention includes an evaporation crucible containing a metal raw material, and an electronic device for heating and evaporating the metal raw material. In a metal vapor generation device in which an electron beam generation device for emitting a beam and an electron beam generation device are housed in a vacuum container, a plurality of porous bodies impregnated with molten metal are installed in the evaporation crucible, and the metal vapor is emitted from the electron beam generation device. The porous body is alternately irradiated with electron beams.

Further, in order to solve the above-mentioned problems, the metal vapor generator of the present invention has two porous bodies in one evaporation crucible.
In order to solve the above-mentioned problems, an evaporation crucible is used in which the porous bodies are arranged integrally or integrally in parallel at intervals, and the electron beams from the electron beam generator are alternately irradiated onto each porous body. A plurality of crucibles are housed in close proximity to each other in a vacuum container, and a porous body is housed in each of the evaporation crucibles.

(Function) This metal vapor generator has a plurality of porous bodies impregnated with molten metal as a metal raw material in an evaporation crucible, and an electron beam emitted from an electron beam generator such as an electron gun is passed through each of the above porous bodies. By alternately irradiating the solid body and hitting the surface of the porous body, metal vapor is generated from the surface of each porous body alternately, and the metal vapor is stably evaporated as a whole, increasing the evaporation efficiency of the metal raw material. This is a significant improvement.

(Example) Hereinafter, an example of the metal vapor generator according to the present invention will be described with reference to the accompanying drawings.

FIG. 1 and FIG. 2 show an example in which the metal vapor generating device of the present invention is applied to an isotope separation device. This metal vapor generator 10 includes an evaporation crucible 12 that stores metal raw materials of isotopic metals such as zirconium, uranium, hafnium, platinum, and gadolinium in a vacuum container 11, and a metal raw material contained in the evaporation crucible 12. It has an electron gun 14 as an electron beam generator that heats, melts, and evaporates the electron beam 13.

A metal vapor flow A generated by heating, melting, and evaporating the metal raw material 13 is guided to spread at a predetermined angle and rises. The rising metal vapor flow A is irradiated with a selective excitation laser beam 16 output from a laser device 15. This laser beam 16 has a frequency corresponding to the resonance absorption line of the specific isotope in order to selectively excite the metal atoms (metal vapor) of the specific isotope to be separated.

The specific isotope irradiated with the selective excitation laser beam 16 is excited and ionized, and becomes an ionized isotope with a positive charge. When this ionized isotope passes between electrodes 17 in which positive and negative electrode plates are arranged alternately, it is attracted to the negative electrode side, adsorbed, and collected on the surface of the negative electrode.

On the other hand, isotopic metal atoms that are not ionized (metal vapor)
Since it is not affected by the electric field, it passes through the electric field space between the electrodes 17 and is collected and collected by the collection plate 18 disposed on the secondary side of the electrode 17.

Incidentally, the evaporation crucible 12 of the metal vapor generator 10 is made of copper, tungsten, or the like, and has a cooling passage (not shown) formed therein for guiding cooling water. When forming the evaporation crucible 12 with tungsten material,
It is necessary to mold tungsten at a high pressure of about 2000 kg/cnf, for example.

A storage recess 20 for storing a metal raw material is formed at the top of the evaporation crucible 12, and a plurality of block-shaped porous bodies 21, 22, for example two, are stored in this storage recess 20.

The porous bodies 21 and 22 are formed of tungsten material or ceramic material so as to have continuous pores, and the porosity thereof is, for example, about 70%. The molten metal of the isotope metal raw material is quickly sucked into the porous body 21, 22 with a large porosity by capillary action and is impregnated therein. For example, the two porous bodies 21 and 22 may be integrally arranged side by side with a spacer 24 in between as shown in FIG. It is also possible to have a similar structure. Moreover, even if each porous body 21 is installed in the storage recess 20 via a stand spacer 26 as shown in FIG.
It may also be placed solidly as shown in FIG.

The porous bodies 21 and 22 have, for example, an elongated block shape,
A groove 28 extending in the longitudinal direction is formed approximately at the center of the top. The groove 28 is formed to have a groove width of, for example, about 10+n+++ in consideration of the beam diameter of the electron beam, and the groove shape is determined in consideration of the diffusion rate (diffusion angle) of the metal vapor flow. The diffusivity of metal vapor flow is mainly determined by the groove shape and heating temperature.

The electron beam B emitted from the electron gun 14 is deflected, for example, by about 180 degrees by a deflection magnetic field formed by an external magnetic field coil 30 such as a Helmholtz coil, and is alternately irradiated onto the grooves of the porous body 21 and 22. be done. The molten metal impregnated into the porous body 21.22 by the irradiation with the electron beam B is heated and evaporated from the surface of the porous body 21.22. At this time, the molten metal impregnated in the porous body 21, 22 is irradiated with the electron beam B and does not cause natural convection, so that the irradiation with the electron beam B causes the evaporation of the heated molten metal. The evaporation efficiency of the metal raw material can be significantly improved, for example, several times higher than that of conventional metal vapor generators.

Note that the metal raw material accommodated in the evaporation crucible 12 can be melted by receiving heat from irradiation with the electron beam B, or by directly applying electricity to the conductive porous body 21 and 22 and melting it by heating with a heater. Good too.

Moreover, one porous body 2 accommodated in the evaporation crucible 12
By irradiating the electron beam B onto the porous body 21 or 22, the molten metal impregnated into the porous body 21 or 22 is heated and evaporated. There is a risk that the amount of evaporation of metal vapor may decrease while the surface of the porous body is impregnated.

Therefore, in this metal vapor generator 10, a plurality of porous bodies 2, two in the illustrated example, are installed in the evaporating loop 12.
1.22 is installed, and an electron gun 14 is installed in each porous body 21.22.
By alternately switching and irradiating the electron beams B emitted from the base plate, it is possible to suppress a decrease in the amount of evaporation of metal vapor and obtain a stable metal vapor flow.

In order to alternately irradiate each of the porous bodies 21 and 22 housed in the evaporation crucible 12, the voltage applied to the external magnetic field coil 30 may be switched. The switching speed is several H
z to several tens of Hz, and the irradiation time per time of each porous body 21.22 is 200 p sec or more, - for example, 1
Approximately 0mm5ec is considered. Irradiation time is 200μs
This is because if it is less than ec, it does not contribute to the evaporation of the molten metal.

When two porous bodies 21 and 22 are housed in the evaporation crucible 12, specific electron beam B irradiation is performed by first irradiating one of the porous bodies 21 with an electron beam B of, for example, 3500 mm. Heating and vaporizing molten metal. When the amount of evaporation of metal vapor from the surface of the porous material decreases or disappears,
The irradiation of the electron beam B is switched to irradiate the other porous body 22 to heat and evaporate the molten metal from the surface of the other porous body. While the other porous body 22 is being irradiated with the electron beam B, the surface of the one porous body 21 is once again impregnated with molten metal. Considering the impregnation speed of this molten metal, after this impregnation, the electron beam B is irradiated on one of the porous bodies 2.
The switching speed for switching to 1 is adjusted, and this switching is repeated thereafter.

By alternately generating metal vapor by switching the irradiation of the electron beam B, metal vapor can be stably generated and a decrease in the amount of metal vapor can be prevented.

FIG. 5 shows another modification of the evaporation crucible used in the metal vapor generator of the present invention. This evaporation crucible 12A has two (plurality of) porous bodies 31 and 32 accommodated in the housing recess 20, each having a semicircular rounded top, so that when the electron beam B is irradiated, the porous bodies 31 and 32 Even if the constituent materials 31 and 32 should melt, the liquid of the melted constituent materials is removed by being struck with an electron beam B and allowed to flow down to prevent it from accumulating on the surface of the porous bodies 31 and 32. For this purpose, the porous bodies 31, 32 may have any shape that slopes downward from the top surface, and are not limited to an arcuate roundness.

FIG. 6 shows a second embodiment of the metal vapor generator of the present invention.

The metal vapor generator 10A shown in this embodiment has two (or more than one) evaporation crucibles 35 and 36 arranged in close proximity in a vacuum container (not shown), and each evaporation crucible 35
．． One porous body 37, 38 is housed in each of the evaporation crucibles 35, 36, and the electron beam B emitted from the electron gun 39 as an electron beam generator is alternately applied to the porous body 37, 38 of each evaporation crucible 35, 36. This is the result of switching irradiation.

Further, the metal vapor generator may be configured as shown in FIG. In this metal vapor generator 10B, one porous body 37, 38 is housed in each of two (or more than one) evaporation crucibles 35, 36, and each porous body 37, 38 is , each corresponding electron gun 40.
41 was used. In this case, the electron gun 40.4
1, the electron beams B and B are alternately irradiated from each electron gun 40.41 onto the porous body 37.38 of the corresponding evaporation crucible 35.36.

In the embodiment of the present invention, an electron beam emitted from an electron gun as an electron beam generator is deflected by a deflecting magnetic field.
An example of irradiation with an 80 degree deflection was shown, but this electron gun 4
The electron beam B emitted from 4 is deflected by a deflecting magnetic field,
The beam may be irradiated with a deflection of 0 degrees or more, for example, 270 degrees as shown in FIG. By irradiating the electron beam B with a deflection of, for example, 270 degrees, the electron gun 44 is not affected by the evaporating metal vapor, and its reliability is improved and it can be made maintenance-free.

〔Effect of the invention〕

As described above, in the metal vapor generator according to the present invention, a plurality of porous bodies impregnated with molten metal are installed in the evaporation crucible, and the electron beam emitted from the electron beam generator is directed through each porous body. Since the body is irradiated alternately, metal vapor is generated alternately from each porous body, so that the amount of metal vapor generated can be stably ensured, and the evaporation efficiency of the metal raw material can be improved.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment in which the metal vapor generator according to the present invention is applied to an isotope separation device, and FIG. 2 is a perspective view showing the isotope separation device of FIG. 1 with the vacuum container removed. FIG. 3 is a diagram showing the principle of the metal vapor generator according to the present invention, FIG. 4 is a diagram showing a first modification of the evaporation crucible used in the metal vapor generator, and FIG. 5 is an evaporation crucible. FIG. 6 is a diagram showing the principle of the second embodiment of the metal vapor generator of the present invention, and FIG. 7 is a diagram showing the third embodiment of the metal vapor generator of the present invention. The principle diagram, FIG. 8, is a diagram showing a modification of the electron beam generator provided in the metal vapor generator. 10, IOA, IOB...metal vapor generator, 11.
...Vacuum container, 12.12A, 35.36...Evaporation crucible, 13...Metal raw material, 14,39,40゜41
．． 44...electron gun (electron beam generator), 15...
・Laser device, 16...Selective excitation laser beam, 17...
・Electrode, 18... Collection and recovery plate, 20... Storage recess,
21.22.31, 32.37.38...Porous body.

Claims (1)

[Scope of Claims] 1. A metal vapor generation device in which an evaporation crucible containing a metal raw material and an electron beam generator for emitting an electron beam for heating and evaporating the metal raw material are housed in a vacuum container, A metal vapor generator characterized in that a plurality of porous bodies impregnated with molten metal are installed in an evaporation crucible, and the porous bodies are alternately irradiated with electron beams emitted from an electron beam generator. 2. Two porous bodies are placed in one evaporation crucible integrally or in parallel at intervals, and each of the porous bodies is alternately irradiated with an electron beam from an electron beam generator. The metal vapor generator according to claim 1. 3. The metal vapor generating device according to claim 1, wherein a plurality of evaporation crucibles are housed in close proximity to each other in a vacuum container, and a porous body is housed in each of the evaporation crucibles.