STUDY OF THE DYNAMICS OF HIGHLY IONIZED CAPILLARY DISCHARGE PLASMAS FOR XUV LASERS

该项目将研究快速放电产生的高电离毛细等离子体的动力学，并探索在紧凑和简单的放电装置中放大极端紫外线辐射的可能性。在毛细几何结构中高效的功率密度沉积可以产生高深宽比体积的高电离等离子体。大量电子热传导到毛细管壁，在电流脉冲结束时提供快速的等离子体冷却。这些条件是极端紫外线复合激光方案的理想条件。我们已经演示了利用仅5焦耳(1010W/cm~3)的放电能量产生直径500微米、长4厘米、温度约为30 eV、密度为1*1018 cm-3的毛细管等离子体，并观察到在等离子体复合过程中类氢锂的3-2跃迁的激发。考虑到复合等离子体中增益随Z的有利标度，我们将研究一种新型的毛细管放电的动力学，这种新型的毛细管放电具有更短的脉冲宽度和更高的功率密度(1013W/cm3)，关于BV(26.2 nm)和CVI(18.2 nm)3-2跃迁被放大的可能性。在电流脉冲期间产生的等离子体条件对于研究相对较低的Z离子的类Ne跃迁的碰撞激发也是感兴趣的，从而在28-70 nm光谱区域产生激光辐射。利用XUV光谱技术和亚皮秒激光诊断技术测量等离子体电阻率并独立确定等离子体密度和温度，将使我们能够研究支配等离子体行为的基本物理过程，并为输运理论提供检验。

This project will study the dynamics of highly ionized capillary plasmas created by fast discharges and explore the possibility of amplifying extreme ultraviolet radiation in a compact and simple discharge device. Efficient power density deposition in a capillary geometry can generate highly ionized plasmas with a high aspect ratio volume. Large electron heat conduction to the capillary walls provides rapid plasma cooling at the end of the current pulse. These conditions are ideal for an extreme ultraviolet recombination laser scheme. We have already demonstrated the generation of capillary plasmas 500 micrometers in diameter and 4 cm long with a temperature of approximately 30 eV and a density of 1*1018cm-3 utilizing a discharge energy of only 5 Joules (1010W/cm3), and we have observed excitation of the 3-2 transition in hydrogenic lithium during plasma recombination. Considering the favorable scaling of the gain with Z in a recombining plasma, we will study the dynamics of a new type of capillary discharges, of shorter pulsewidths and higher power density (1013 W/cm3), in relation to the possibility of amplification of the 3- 2 transitions of BV (26.2 nm) and CVI (18.2 nm). The plasma conditions that will be generated during the current pulse are also of interest in the study of collisional excitation of Ne-like transitions of relatively low Z ions for the generation of laser radiation in the 28-70 nm spectral region. The measurement of plasma resistivity and the independent determination of the plasma density and temperature using XUV spectroscopic techniques and subpicosecond laser diagnostics will allow the study of fundamental physical processes governing the plasma behavior and provide a test for transport theories.