Isotope Separation by Lasers

与激光同位素分离相关的是激光技术的发展、激光与原子/分子相互作用的研究以及光电离原子的收集。1）在激光技术方面，利用半导体激光器和两级磁脉冲压缩器成功地研制了大口径铜蒸气激光器的全固态开关。2）在激光与原子相互作用中，对啁啾激光绝热快速通过方案进行了理论分析和实验研究。从频率扫描速度和峰值激光强度两个方面估计了实现粒子数完全反转的条件。实验结果与理论分析结果吻合较好。3）研究了双色激光脉冲在共振三能级介质中的传输。通过数值求解三能级布洛赫-麦克斯韦方程组，分析了激光脉冲形状和原子布居数随时间的变化。观察到脉冲延迟和脉冲破碎，特别是对于第一个激发激光脉冲。结果表明，电离效率的急剧下降是由两束激光脉冲的分离引起的。4）发展了一种新的测量金属原子电荷转移截面的交叉束技术。由激光光电离的一个原子束产生的脉冲离子束与第二个原子束碰撞。在10- 1000 eV范围内，测量了Gd、Y和U的电荷转移截面随能量的变化。通过简单的分析模型，与理论预测值相比，测量值相当大。

Related to the laser isotope separation, developments of laser technologies, researches on laser-atom/molecule interaction and collection of photoionized atoms have been performed.1) In laser technology, all solid state switches for large-bore copper vapor laser (CVL) have been successfully developed by using SI thyristors and two-stage magnetic pulse compressers. Without hydrogen thyratron switches, the life of CVL power supply was greatly improved.2) In laser-atom interaction, the adiabatic rapid passage scheme by using a frequency chirped laser has been investigated analytically and experimentally. The conditions to achieve complete population inversion were estimated with respect to the frequency scanning velocity and the peak laser intensity. The experimental data show a fairly good agreement with the analytical ones.3) The propagation of two-different-color laser pulses in the resonant three-level medium has been studied. The three-level Bloch-Maxwell equations were solved numerically to analyze the change of the laser pulse shapes and the timevarying atomic populations. The pulse delay and pulse break-up were observed especially for the first excitation laser pulse. It is shown that the rapid decrease of the ionization efficiency is caused by the separation of the two laser pulses.4) A new cross-beam technique has been developed to measure the charge transfer cross sections of metallic atoms. A pulsed ion beam produced from one atomic beam by laser photoionization was collided with the second atomic beam. The charge transfer cross sections of Gd, Y and U have been measured as a function of impact energy in the range of 10-1000eV. The measured values are fairly large compared with the theoretically predicted ones by using a simple analytical model.