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

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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.