Ways to discharge-based soft X-ray lasers with the wavelength λ<15 nm
Ways to discharge-based soft X-ray lasers with the wavelength λ<15 nm
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DOI：
10.1017/s0263034608000190
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发表时间：
2008-06
影响因子：
0.9
通讯作者：
K. Kolacek;J. Schmidt;V. Prukner;O. Frolov;J. Straus
中科院分区：
文献类型：
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作者：
K. Kolacek;J. Schmidt;V. Prukner;O. Frolov;J. Straus
描述了在软 X 射线区域放大自发发射的两种基本方法。第一个是基于电子碰撞重组泵浦方案，该方案利用完全剥离的离子重组为类氢离子，以在属于巴尔默-α跃迁的能级上产生（在足够快的冷却情况下）粒子数反转。我们在氮气上测试了该方案，其激光波长为 13.4 nm。放大自发发射的第二种方法是基于电子碰撞激发泵浦方案：该方案使用 Ne- 或 Ni-like 离子的快速激发来创建粒子数反转。然而，对于低于 15 nm 的波长，有必要使用某些金属蒸气的类 Ni 离子。将金属蒸气送入毛细管是很困难的，如果送入，它们会沉积在毛细管壁上并显着缩短毛细管的寿命。这就是为什么我们在带有液壁的毛细管中通过在水中爆炸的方式制备金属蒸气等离子体。为了减缓等离子体通道的扩张，正在开发一种通过线性聚焦冲击波进行局部水压缩的方法。
Two basic ways to amplification of spontaneous emission in the soft X-ray region are described. The first is based on the electron-collisional recombination pumping scheme, which uses recombination of fully stripped ions into hydrogen-like ions to create (in the case of sufficiently fast cooling) a population inversion on energy levels belonging to the Balmer-alpha transition. We test this scheme on nitrogen, for which the lasing wavelength is 13.4 nm. The second way to amplification of spontaneous emission is based on the electron-collisional excitation pumping scheme: this uses for creation of population inversion a fast excitation of Ne- or Ni-like ions. However, for wavelength below 15 nm it is necessary to use Ni-like ions of some metal vapors. Feeding metal vapors into a capillary is difficult, and if being fed they deposit on the capillary wall and significantly reduce the capillary lifetime. That is why we prepare metal vapor plasma in a capillary with liquid wall – by wire explosion in water. For slowdown of the plasma-channel expansion a local-water-compression by linearly focused shock wave is being developed.