JPH01249128A - Isotope separator - Google Patents

Abstract

PURPOSE:To reduce the amt. of ionized isotopes as the impurities to be incorporated into the product by imparting a DC electric field orthogonal to a DC deflection magnetic field before a metal vapor current is introduced into an isotope collector. CONSTITUTION:The metal atoms 1 contg. plural isotopes are charged in a vessel 2 with the upper surface opened and having thermochemical resistance. A DC deflection magnetic field 6 orthogonal to an electron beam 5 from its generator 4 is generated by a magnetic field generating means to project the beam onto the surface of the metal atoms 1. The vapor current 7 formed by the metal atoms 1 heated and melted by the electron beam 5 is induced in a vapor passage 17. The laser light 11 for selectively exciting and ionizing the specified isotope contained in the metal atoms 1 is emitted in an irradiation means, and injected into the vapor current 7. An electric field is generated by the electrode 15, and exerted on the ionized isotope to adsorb and recover the isotope. A DC electric field 18 orthogonal to the DC deflection magnetic field 6 is imparted by the electric field generator 21 provided in the vapor passage 17.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to an isotope separation device for metal atoms using a laser method, and in particular prevents the incorporation of impurity ions and improves isotope separation performance. Regarding the isotope separation device.

(Prior art) In general, it is often done to separate a specific isotope from a substance containing multiple isotopes and utilize it by extracting the characteristics of this specific isotope. Money to do, I2! For example, the c atom contains a small amount of a first isotope with a lighter mass number, and most of the remainder is a second isotope with a higher mass number, and the first isotope is separated from this metal atom and used. There are cases.

Conventionally, gas diffusion methods, centrifugation methods, laser methods, etc. have been used to separate the first isotope from metal atoms containing such isotopes and increase the concentration to a predetermined concentration level.
In both cases, separation and concentration operations are performed using differences in the chemical or physical properties of isotopes.

Here, we are talking about an isotope separation device using the laser method. A metal raw material containing multiple isotopes is heated and melted and evaporated, and the generated metal vapor flow is irradiated with laser light to separate characteristic isotopes in the vapor flow. For example, the first isotope is selectively cationized, and an electric field is applied to the cationized first isotope to separate and recover it.

An example of an isotope separation apparatus using this laser method will be explained with reference to FIGS. 4 and 5.

FIG. 4 is a perspective view schematically showing the configuration of an isotope separation apparatus using a laser method, and FIG. 5 is a cross-sectional view taken along line 1-1 in FIG. 4.

In FIGS. 4 and 5, metal atoms containing isotopes 1
is a thermochemically resistant evaporation container 2, such as a crucible.
loaded inside. This evaporation container 2 is installed at the inner bottom of a sealed container 3 that is maintained in a nearly vacuum state. Next, the electron beam 5 emitted from the linear electron gun 4 is deflected by a DC magnetic field 6 applied by an external magnetic field coil (not shown) and irradiated onto the metal atoms 1 in the evaporation container 2. The metal atoms 1 irradiated by the electron beam 5 are heated to a high temperature and evaporated, forming a vapor flow 7 . The vapor flow 7 contains, for example, two types of isotopes constituting the metal atoms 1.

On the other hand, above the evaporation container 2, band-shaped positive electrodes 8 and negative electrodes 9 are arranged alternately, and a photoreaction section 10 is provided between each of these electrodes. A laser beam 11 that selectively excites and ionizes only the first isotope of the two types is generated and incident by a laser generator 12, and undergoes a photoreaction with the vapor flow 7. The wavelength of the laser beam 11 is adjusted to the resonant ionization wavelength of the first isotope described above, and only the atoms of the first isotope contained in the vapor flow 7 introduced into the photoreaction section 10 interact with the laser beam 11. It resonates and is selectively ionized with a certain probability.

The ionized first isotope ions are transferred to the positive electrode 8 and the negative electrode 9.
8 is adsorbed and collected on the surface of the cathode 9, which serves as a collection electrode, by an electric field created by applying an electrode voltage synchronized with the laser beam 11 between the 8 and 8, while passing through the photoreaction part 11 without being ionized. The mixed vapor flow of the first isotope and the second isotope is suctioned and collected by the vapor recovery plate 13 disposed at the outer edge of the photoreaction section IO. The collected vapor particles are returned to the evaporation container 2 by a separate means.

(Problems to be Solved by the Invention) According to the above-described isotope separation apparatus, in the pretreatment for isotope separation operation, metal atoms are irradiated with a powerful electron beam to melt and evaporate them at high temperatures to form a vapor stream. Since the method includes a step of generating , the generated vapor flow contains various impurity ions generated under high temperature conditions.

Examples of impurity ions include collision ionized ions of a second isotope generated when an electron beam, which is a heating source for metal atoms, collides with a metal vapor flow, and secondary isotope ions generated when a metal vapor flow contacts a high-temperature heat source. isotopes and thermoionized ions of other metals.

Therefore, when a DC electric field is applied between the positive and negative electrodes through which a metal vapor flow containing these impurity ions flows,
The impurity ions are absorbed along with the first isotope ions into the negative electrode, which serves as the collection electrode.

As a result, the separation coefficient of the target isotope decreases and the degree of enrichment decreases, causing a decrease in the purity quality of the recovered first isotope.

The present invention has been made to solve the above-mentioned problems, and by providing a means for eliminating impurity ions contained in a metal vapor flow before it is introduced into an isotope collection device, impurity ions can be removed. The purpose of the present invention is to provide an isotope separation device that reduces the amount of ionized isotopes mixed into a product, maintains a high separation coefficient that is an indicator of separation efficiency, and provides a product with high purity.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a thermochemically resistant top open container containing metal atoms containing a plurality of isotopes, and a container disposed on the side of the container. a magnetic field generating means for providing a DC deflection magnetic field perpendicular to the electron beam and projecting it onto the surface of the metal atoms; A vapor flow path that guides a vapor flow in which metal atoms are generated, and a vapor flow path that is arranged from above the vapor flow path and that is incident on the vapor flow to selectively excite and ionize specific isotopes contained in the metal atoms. An isotope separation device has an irradiation means that emits ionized laser light, and an electrode that applies an electric field to the ionized isotope and adsorbs and collects it. An electric field generator was installed to provide a DC electric field perpendicular to the .

(Function) Specific isotopes contained in the evaporated flow of metal atoms heated and melted by the electron beam and ionized by the laser beam are adsorbed and collected by electrodes of opposite polarity. In addition to ions of specific isotopes that are characterized by recovery, the steam flow contains isotopes that have been ionized by thermal ionization or collision with electron beams, and thermoelectrons liberated from these ionized isotopes. Furthermore, the electron beam contains charged particles such as high-speed electrons that are reflected and dissipated on the metal atoms housed in the container, but since a DC electric field orthogonal to the DC deflection magnetic field is applied to the vapor flow path, these The charged particles are deflected by the electromagnetic drift caused by the DC deflection magnetic field and the DC electric field, and are alienated from the vapor flow, making it extremely rare for them to reach the electrodes that adsorb and collect isotopes. Therefore, only the specific isotope ionized by the laser beam is collected in the electrode, and the amount of impurities mixed in can be extremely reduced.

(Example) An example of the present invention will be described below with reference to FIG. FIG. 1 is a sectional view showing the structure of an embodiment of an isotope dispensing device according to the present invention. Note that the same components and parts as in the conventional example shown in FIGS. 4 and 5 are given the same reference numerals.

The isotope separation device includes an evaporation container 2 containing metal atoms 1
and a vapor generation device 14 that heats and evaporates the metal atoms 1 by irradiating the metal atoms 1 housed in the evaporation container 2 with an electron beam 5 emitted from a linear electron gun 4 to generate a vapor flow 7. There is. Above this steam generator 14,
An isotope collection device 15 formed by alternately arranging positive electrodes 8 and negative electrodes 9 is provided. A photoreaction section 10 is formed between the positive electrode 8 and the cathode 9, and the vapor flow 7 flowing through this photoreaction section 10 is irradiated with an ionizing laser beam 11. The isotope ionized by the irradiation with the ionizing laser beam 11 is deflected toward the recovery electrode by an electric field formed between the positive electrode 8 and the negative electrode 9 by the power supply bag [16] and separated.

between the steam generator 14 and the isotope collector 15.

A vapor flow passage 17 for the vapor flow 7 flowing radially from the evaporation vessel 2 is provided, and a DC electric field 18 for applying a DC electric field 18 intersecting the DC magnetic field 6 for deflecting the electron beam 5 to the vapor flow passage 17 is provided. It is equipped with a power supply device 119 and a DC electric field generating bag W121 consisting of an auxiliary electrode (anode) 20a and an auxiliary electrode (cathode) 20b arranged on both sides of the steam flow path 17.

That is, the DC electric field generating bag @21 is configured to generate a DC electric field 18 in the steam flow path 17 that is perpendicular to the direction of the steam flow 7 and the direction of the DC magnetic field 6.

Next, the effect of this will be described.

is the steam flow 7-! generated from the steam generator 14. -1 Isotopes ionized by thermal ionization or collision ionization with the electron beam 5, thermal electrons liberated from the ionized isotopes, and charged particles such as high-speed electrons that are reflected and dissipated by the electron beam 5 on the metal atoms 1. Contains.

That is, the impurity ions and electrons by-produced from the steam generator 14 are influenced by the DC electric field 18 and the DC magnetic field 6 as soon as they flow into the steam flow path 17 . The behavior of charged particles in mutually crossing DC electromagnetic fields is
It is described as a drift motion in an electromagnetic field as shown in FIG.

In the configuration of this embodiment, the impurity ion streams 22a, 22b and the electron stream 23 are pushed back toward the steam generator 14.

It does not reach the isotope collector 15 together with the vapor stream 7.

The above operation will be explained in detail below with reference to FIGS. 2 and 3. FIG. 2 shows particle behavior in the steam flow path 17 in FIG. 1, and the neutral atoms 24 that make up the majority of the steam flow 7 will not be affected by collision scattering between neutral atoms. It moves on a straight trajectory 25 regardless of the influence of electromagnetic fields. With this N, the average velocity Pa of the neutral atoms 24 is 1. For example, when the operating temperature T is 2700, the atomic substance ff1m is 3.952X10
−”kg, Boltzmann constant k is 1.381 × 1O−
If it is set to 23J/, it becomes the following formula 0.

The ions 26 have an average velocity similar to that of formula 0, but the DC electric field 18 is set to E = IOV/m, and the DC magnetic field 6 is set to B = 10.
−”iib/rr?, then orbit 22 of ion 26
a becomes a spiral motion as shown in the figure, and the electric field Σ and magnetic flux density B
It moves in the opposite direction to the neutral atom 24 at a drift velocity td in the field given by the equation 0.

However, B represents the size of B.

The electrons 27 also drift in the same direction and at the same speed as the ions 26, making a spiral motion similar to the orbit 28 and preventing charged particles from flowing into the isotope collection device above. . Strictly speaking, neutral atoms 24 and ions 26
Due to collision scattering with
By setting d sufficiently larger than the atomic velocity Pa, the ion blocking effect can be maintained.

? d>? Since a 00 formula and 0 formula satisfy 0 formula, in this example, ion 2
6 is removed from steam stream 7 and returned to steam generator 14 . At this time, since the mobility of the electrons 27 in the electromagnetic field is extremely greater than that of the ions 26, the electrons 27 move in accordance with the ions 26 and try to maintain electrical neutrality as a charged particle flow.

Also, the drift velocity as a parameter describing the drift motion of the ion 26? In addition to d, the turning radius γ.

, the mass J of ion 26 is approximately atomic mass m = 3.9
52 x 10-" kg, the velocity component V of the ion 26 perpendicular to the magnetic field 6 is approximately equal to the equation 0, and assuming that the ion 26 is a monovalent ion using the charge amount of the ion 26 as a spear, f = 1. By setting .602 x 10-''c, the radius of gyration γC of the ions 26 is given by equation (A).

miy upper γC: B msu α□yu0.12m (a) B In other words, the turning radius γ shown in equation (a). is steam flow passage 17
Since it is sufficiently small compared to the width of Furthermore, there is a collision process with the neutral atom 24 that inhibits the swirling motion, but the mean free path λ in the collision process is 5, Ox 1O-19rrr, where the collision cross section σ is 5.
, when the atomic number density n is 101 m, -3, it is obtained as shown in equation 0, and in this example, the mean free path λ is the radius of gyration γ, as shown in equation 0. , and the inhibition of turning motion due to collision is not very effective.

λ〉γ. 0
Also. The average velocity va of the neutral atoms 24 is given as shown in the formula 0, but strictly speaking, the velocity of the neutral atoms 24 is determined by the velocity distribution function, and the velocity in the formula 0 is only a statistical average value, so it is stochastic. There may also be fast neutral atoms in
The same applies to ions. Figure 3 illustrates this behavior for fast ions, with radius of gyration γ. becomes larger and moves like the orbit 22b. At this time, the turning radius γ is larger than the width of the steam flow passage 17, that is, the gap length of the auxiliary electrodes 20a and 20b. becomes large, and the high-speed ions are no longer able to drift toward the steam generator 14 and are collected by the auxiliary electrode 20b.

As described above, impurity ions and electrons generated by the irradiation of the electron beam 5 and mixed into the vapor flow 7 are removed from the vapor flow path 17.
It is removed in advance by a DC electric field generator 21 disposed at. Therefore, the vapor flow 7 flowing into the photoreaction part 1O does not contain charged particles as impurities, and can be supplied with a vapor flow 7 consisting only of electrically neutral components. Therefore, it is possible to significantly reduce the amount of impurities attracted to the collection electrode of the isotope collection device 15, improving the isotope separation coefficient of the device as a whole, and efficiently obtaining isotopes with excellent purity quality. be able to. Note that the operating procedure after introducing the vapor stream 7 into the photoreaction section 10 is similar to that in conventional devices.

Furthermore, according to this embodiment, there is no need to make any drastic modifications to the equipment configuration of the existing isotope separation device; in other words, simply by newly equipping the steam flow path with a DC electric field generator, the electrons contained in the steam flow can be ionized. Charged particles such as isotopes and metal ions can be easily removed.

In addition, in the present invention, when the right-hand screw is rotated from the direction of the DC electric field to the direction of the DC deflection magnetic field from the DC electric field to the direction of the DC deflection magnetic field, the traveling direction of this right-handed screw is the traveling direction of the steam flow (
(increasing) and in the opposite direction.

According to the present invention, it is possible to significantly reduce the amount of impurities attracted to the recovery electrode of the vapor complementation device of the isotope separation device. Therefore, the separation coefficient, which is an index of the motion efficiency of the isotope separation device, is high, and the purity and quality of the separated and recovered isotope products can be greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view schematically showing one embodiment of the present invention, and FIG.
3 and 3 are schematic diagrams for explaining the action of FIG. 1, and FIG. 4 is a perspective view showing the main parts of a conventional isotope separation device.
FIG. 5 is a sectional view taken along line 1-1 in FIG. 4. 1... Metal atom 2... Evaporation container 4...
・Linear electron gun 6...DC magnetic field 7...vapor flow 9...cathode 11...laser light
17... Steam flow path 18... DC electric field
21... DC electric field generator agent Patent attorney Nori Ken Chika Yudo Ken Daishimaru Figure 1 Figure 2

Claims (1)

[Claims] 1. A thermochemically resistant top-open container containing metal atoms containing a plurality of isotopes; an electron beam generating means disposed on the side of the container; magnetic field generating means for providing a direct current deflection magnetic field that causes the metal atoms to be projected onto the surface of the metal atoms; and a vapor flow passage that is disposed above the container and that guides a vapor flow generated by the metal atoms heated and melted by the electron beam. irradiation means disposed above the vapor flow path and emitting a laser beam that is incident on the vapor flow and capable of selectively exciting and ionizing specific isotopes contained in the metal atoms; an isotope separation device having an electrode that applies an electric field to the isotope and adsorbs and collects the same, an electric field generator provided in the vapor flow path and providing a DC electric field orthogonal to the DC deflection magnetic field. An isotope separation device featuring: