| Project/Area Number |
59880002
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| Research Category |
Grant-in-Aid for Developmental Scientific Research
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| Allocation Type | Single-year Grants |
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| Research Field |
プラズマ理工学
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| Research Institution | Osaka University |
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Principal Investigator |
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| Project Period (FY) |
1984 – 1985
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| Project Status |
Completed (Fiscal Year 1985)
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| Budget Amount *help |
¥5,600,000 (Direct Cost: ¥5,600,000)
Fiscal Year 1985: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1984: ¥3,900,000 (Direct Cost: ¥3,900,000)
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| Keywords | Laser plasma / Uranium enrichment / Nuclear excitation / 核異性体 |
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| Research Abstract |
Nuclear excitation of <^(235)U> in a laser produced uranium plasma has been investigated experimentally and theoretically. This scheme may be applicable to uranium enrichment.
A metallic natural uranium target was irradiated by a focused <CO_2> laser beam. The 26 min isomers of <^(235)U> were produced by NEET (Nuclear Excitation by Electron Transition), which were confirmed by detecting the internal conversion electrons from the isomeric level of <^(235)U> nucleus.
The probability of the nuclear excitation of <^(235)U> in the laser produced plasma was estimated from the number of the excited nuclei. The value experimentally obtained was fairly in good agreement with the theoretically expected value.
The temperature dependence of the excitation rate to the isomeric level in the plasma was measured by varying the focusing condition of the laser beam to the uranium target, and was compared with the theoretically predicted dependence. When the electron temperature is lower than 50eV, the production of the isomer was not observed. The electron temperature of 400-500eV is favorable for the nuclear excitation of <^(235)U> in the plasma.
The efficiency of nuclear excitation increased linearly with the electron density of the plasma, which was confirmed from the comparison of the excitation rates by 1 <micro> m (Nd:YAG laser) and 10 <micro> m ( <CO_2> laser) irradiations. This shows the availability of the pellet implosion to improve the production rate of <^(235)U> isomers.
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