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，利用精细调谐的激光对靶同位素进行选择性激发，称为同位素位移。然而，在元素具有很小的同位素位移的情况下，或者在奇同位素的超精细结构扩散覆盖其他不需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可取的。在这项研究中，我研究了这种分离方法在Gd和Zu的浓集同位素中的应用，特别是在核技术领域。并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研制开发了原子激发动力学数值分析程序。同位异顶…的降解由于磁场的影响破坏了原子的排列，所以产生了更高的离子选择性。激光激发的磁子能级之间的垂直跃迁由速率方程或密度矩阵运动方程描述，而磁场的横向跃迁由Larmor进动方程描述。利用上述程序分析了磁场对同位素选择性的影响。研究发现，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3个高斯的场强就可能完全丧失同位素的选择性。激光同位素分离实验研究。激光同位素分离实验的初步结果表明，浓缩倍数约为8。为确保数值分析的结果，还需进行进一步的实验研究。较少

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