Selectivity in Laser Isotope Separation based on Polarization Selection Rules

在原子激光同位素分离过程中，利用同位素吸收峰的光谱差异（称为同位素位移），通过精细调谐的激光选择性地激发目标同位素。然而，在元素具有非常小的同位素位移的情况下或者在奇数同位素的超精细结构扩展覆盖其他不想要的同位素吸收峰的情况下，基于偏振选择规则的同位素分离方法是相当优选的。本论文研究了这种分离方法在核技术领域中非常有用的钆和锆富集同位素中的应用。数值分析了外加磁场对同位素选择性的影响。以下是本研究取得的主要成果.原子激发动力学数值分析程序的研制开发了原子激发动力学数值分析程序。同位素降解 ...更多信息 由于磁场的影响破坏了原子排列，所以出现IC选择性。由激光激发的磁子级之间的垂直跃迁由速率方程或密度矩阵运动方程描述，由磁场引起的横向跃迁由Larmor进动方程描述.磁场对同位素选择性的影响利用上述程序分析了磁场对同位素选择性的影响。结果表明，激光强度不是影响选择性的重要因素，而磁场强度和磁场与激光偏振方向的夹角是影响选择性的重要因素。结果表明，对于Gd的情况，仅需3高斯的场强，同位素选择性就可能完全丧失. Zr的激光同位素分离实验原始结果表明，Zr的激光同位素分离实验<91>的富集因子约为8。数值分析结果的可靠性有待于进一步的实验研究。少

In the atomic laser isotope separation process the target isotope is selectively excited by a finely tuned laser making use of a spectral difference of isotopic absorption peak so called isotope shift. In the case that element has a very small isotope shift or in the case that the hyperfine structure spread of the odd isotope covers other unwanted isotope absorption peak, however, the isotope separation method based on the polarization selection rules is rather preferable. In this research I studied the application of this separation method on Gadolinium and Zirconium enriched isotopes of which are very useful especially in the field of nuclear technology. And the influence of an external magnetic field on the isotopic selectivity was numerically analysed. The following are the main results obtained in this research.1. Development of the numerical analysis code of atomic excitation dynamicsThe numerical analysis code of atomic excitation dynamics is developed. Degradation of the isotop … More ic selectivity occurs because the atomic alignment is destroyed the influence of a magnetic field. Vertical transitions between magnetic sublevels by laser excitations are described by the rate equations or the density matrix equation of motion, and transverse transitions by an magnetic field are by the Larmor precession equation.2. Influence of a magnetic field on the isotopic selectivityBy using the code described above the influence of a magnetic field on the isotopic selectivity was analysed. It Was found that the laser intensities are not the significant factors for the selectivity but the magnetic field strength and the angle between the magnetic field and the laser polarization are. Results shows that for Gd case the isotopic selectivity may be completely lost by the field strength of only 3 gauss.3. Laser isotope separation experiment of ZrPrimitive results of the laser isotope separation experiment of ^<91>Zr showed the enrichment factor of about 8. Further experimental investigations are to be performed for making sure of the numerical analyses results. Less