1995 Fiscal Year Final Research Report Summary
Study on laser beam breakup effects in atomic laser isotope separations of uranium
| Project/Area Number |
06452431
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
エネルギー学一般・原子力学
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| Research Institution | Osaka University |
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Principal Investigator |
IZAWA Yasukazu Institute of Laser Engineering, Professor, レーザー核融合研究センター, 教授 (10029316)
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| Co-Investigator(Kenkyū-buntansha) |
CHEN Yen-wei Ryukyu University, Faculty of Engineering, Assistant Professor, 工学部, 講師 (60236841)
SAKABE Shuji Faculty of Engineering, Assistant Professor, 工学部, 講師 (50153903)
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| Project Period (FY) |
1994 – 1995
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| Keywords | AVLIS / near-resonant effects / laser beam propagation / spatial nonuniformity / self-focusing / nonlinear refractive index / beam breakup |
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| Research Abstract |
In atomic vapor laser isotope separations of uranium, the laser beams propagate through the uranium atomic vapor for a long distance in interacting with U-235 on resonance and U-238 in near-resonance. The nonuniformity in spatial intensity distribution of incident laser pulse will be amplified by nonlinear effects of near-resonant interaction (nonlinear refractive index) during the propagation, which leads the laser beam breakup. In this study, the growth of nonuniformity and the effects of such growth on uranium enrichment have been investigated by the experiments and the numerical calculations.
1) The 2-D simulation code named CEALIS-P-2P has been developed to study the spatial effects in laser beam propagation and atomic excitation simultaneously in multilevel photoionization system.
2) In the simulations, the effects of diffraction and the growth of nonuniformity on the ionization rates of target atoms have been successfully analyzed. When the incident laser beam is highly nonuniform, it was found that the ionization rate suddenly decrease after a critical distance of propagation. The nonuniformity should be less than <plus-minus>5% for atomic laser isotope separation of uraniu
3) The growth of nonuniformity was observed experimentally in the dye laser pulse propagating in the Na vapor in near-resonant conditions. By increasing nonlinear refractive index, the growth moves from linear region to nonlinear region which induced the higher harmonics components and finally the beam breakup. These features are in good agreements with the simulation results.
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