JPH0716083B2 - Method for improving efficiency of copper vapor laser - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser efficiency improving method, and in particular, a copper vapor laser capable of enhancing the efficiency of a metal copper vapor laser and a copper halide vapor laser. Related to the method of increasing efficiency.

[Conventional technology]

Today, the development and application of lasers are remarkable, and the fields of application are not limited to conventional machining, optical communication, and medical fields,
It is being used in the fields of laser fusion and laser uranium enrichment, and is drawing attention.

Especially, the importance of the laser uranium enrichment technology has been recognized from the viewpoint of energy measures in Japan, and its results are expected.

3% enriched uranium, which is a nuclear reactor fuel, is currently manufactured by the gas diffusion method, but the cost increases year by year, and 1970
Today, it is about 6 times higher than the previous year. However, when the laser method is used, the cost is expected to be about 1/10 to 1/3, which is the reason why remarkable development results are paid attention.

Here, the principle of isotope separation, which is the basis of the laser uranium enrichment method, will be briefly described with reference to FIG.

An atom has its own energy level and can be excited by laser light of an appropriate wavelength. However, even in the same atom, the energy levels are Er and E due to the isotopes A and B.
Slightly different from r '(isotope shift is Er'-Er), only specific isotopes can be excited by using laser light with sufficiently narrow wavelength width. At this time, no change occurs in the isotope that is not excited.

As described above, only a specific isotope can be ionized by using a laser, and can be separated and recovered by applying an electric field.

In the case of uranium atoms, there are many energy states equivalent to visible light, and only ²³⁵ U can be excited by using a dye laser. At present, a dye laser system using a copper vapor laser as an excitation light source is drawing attention as a light source for the laser uranium enrichment method.

[Problems to be solved by the invention]

However, in the conventional copper vapor laser, the excitation average lifetime of the upper level of the copper atom is 10.2 at ² P _1/2 30535 cm ^-1 .
Very short at 9.6 ns at 4 ns, ² P _3/2 30783 cm ^-1 , and because the lower laser level is a metastable level, the population inversion can be established only for a very short time, so only short pulse oscillation is possible. Therefore, high efficiency operation cannot be expected, and the efficiency is currently about 1.2%. Therefore, even if such a conventional copper vapor laser is used for a laser uranium enrichment device, there is a problem that the recovery efficiency of uranium cannot be sufficiently improved.

The present invention is to solve the above problems, the rise of the optical pulse of the copper vapor laser is fast, the oscillation time is extended,
It is an object of the present invention to provide a method for improving the efficiency of a copper vapor laser, which can improve the efficiency of the laser.

[Means for solving problems]

Therefore, the method for enhancing the efficiency of the copper vapor laser of the present invention is to use a cadmium atom as a highly efficient exciter, a molecule, copper metal as a copper vapor laser, and copper halide, and use metal cadmium as a highly efficient exciter. It is characterized by using.

[Action]

The present invention is based on the ³ P ₀ (energy level 301
_{^{14cm -1), 3 P 1 (}} 30656cm -1), 3 P 2 (31827cm -1) it compared the approximately 250 times longer excitation life expectancy of three metastable level is about 2.5μs and copper atoms Energy is transferred to the copper atom in the ground state by interatomic collision, and the laser upper level of the copper atom is ² P _1/2 (30535cm ^-1 ), ² P _3/2 (30783cm
^-1 ) is excited to accumulate discharge energy not only in copper atoms but also in metastable cadmium, which can contribute to oscillation, widen oscillation pulse width, and promote high efficiency. Is possible.

〔Example〕

 The present invention will be described below with reference to FIG.

Figure 1 shows the distribution of energy levels of cadmium and copper atoms.

The lowest energy level of the cadmium atom is almost equal to the laser level of the copper atom, and is a metastable level. That is, the energy level is ³ P ₁ state of 2 No. cadmium atom is is 30656cm ^{-1, 2} P _3/2 of the copper atoms, ² energy level, respectively 30783Cm ^-1 of P _1/2, in comparison with 30535Cm ^-1 127 cm
^-1 and 121 cm ^-1 are in the range where sufficient energy transition can be made, considering the temperature during discharge. Using this metastable level of the cadmium atom, energy is transferred by collision between the cadmium atom and the copper atom. Since the ³ P ₀ , ³ P ₁ , and ³ P ₂ states of the cadmium atom are metastable levels and thus have a long lifetime of 2.5 μs, collisions with the copper atoms cause the laser upper quasi-states of the copper atoms to continue for a long time. Energy can be supplied to the positions, and the population inversion of copper atoms can be made longer.

Further, since the laser lower level of copper atoms is a metastable level, optical energy transition is also prohibited, and the atomic number density of this level increases with the lapse of time of laser oscillation. Due to the increase in the number density of the lower level atoms of the laser, the population inversion necessary for laser oscillation cannot be established. To prevent an increase of the atomic number density of laser low level, ² D _3/2 13245cm ^-1 to ² S copper atoms by collisions between atoms with ³ P ₀ ^{30114cm -1} level No. 1 of cadmium atoms Excitation to _1/2 43137 cm ^-1 .

Similarly to excite the ² D _5/2 ^{11202cm -1} of copper atoms to the ² S _1/2 ^{43137cm -1} using ³ P ₂ ^{31824cm -1} level of third cadmium atoms.

The first ³ P ₀ 30 114 cm ^-1 level of cadmium atom and 4 of copper atom
The difference from the energy from ² D _3/2 to ² S _1/2 is 222 cm
^-1 . Similarly, the 3rd part of the cadmium atom, ³ P ₂ 31824cm ^-1
The difference between the energy of the ² D _5/2 5th and the level of copper atoms to the ² S _1/2 is 108cm ^-1. Considering the plasma temperature, this energy transition process is sufficiently established.

Therefore, the energy of one discharge is stored not only in the copper atoms but also in the cadmium atoms and contributes to the oscillation, so that the optical pulse oscillation time is extended and the efficiency of the copper vapor laser can be improved.

〔The invention's effect〕

As described above, according to the method for improving the efficiency of the copper vapor laser of the present invention, the energy is transferred by the collision between the cadmium atom and the copper atom, the excitation from the ground state of the copper atom, and the laser from the lower level. The population inversion can be made longer by the excitation and the reduction of the atomic number density of the lower level of the laser, and the optical pulse oscillation time (that is, pulse width) is also extended to improve the efficiency of the copper vapor laser.

As a result, the production efficiency of a laser uranium concentrating device or the like using such a copper vapor laser is also increased, which greatly contributes to industry.

[Brief description of drawings]

Figure 1 shows the distribution of energy levels of cadmium and copper atoms, and Figure 2 shows the principle of isotope separation.

Claims (2)

[Claims] 1. A method for increasing the efficiency of a copper vapor laser, characterized in that cadmium atoms and molecules are used as a highly efficient excitation agent for the copper vapor laser. 2. The method for improving the efficiency of a copper vapor laser according to claim 1, wherein metallic copper and copper halide are used as the copper vapor laser and metallic cadmium is used as the highly efficient exciter.