Study of the soft x-ray emission from carbon ions in a capillary discharge

Includes bibliographical references.The soft x-ray emission from plasma produced in polyacetal and polyethylene capillary discharges excited by current pulses 100 ns full-width half-maximum (FWHM), 50 ns risetime, and peak currents up to 60 kA has been studied. Time-resolved spectra show that intense Cᴠɪ line emission dominates in the polyethylene discharges, peaking shortly after the maximum of the current and vanishing before the end of the current pulse. Polyacetal capillary spectra are dominated by Oᴠɪ lines and show weak Cᴠɪ emission. Plasma density and temperature for the polyethylene discharge were derived from the Stark broadening of Cᴠɪ Balmer lines and the relative intensities of Cᴠɪ and Cᴠ lines. A short (5 ns FWHM) pulse of energetic beam electrons was detected in coincidence with the onset of the discharge. The results are discussed in relation to the possibility of obtaining soft x-ray amplification by plasma recombination in a capillary discharge plasma column.This work was supported by the Department of Energy, Advanced Energy Projects Grant DE-F602-91ER12110 and by the National Science Foundation by Grant ECS 9013372. The work of M. C. Marconi was supported by the Universidad Nacional de Buenos Aires and Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina

Lasing at 60.8 nm in Ne-like sulfur ions in ablated material excited by a capillary discharge

Includes bibliographical references (page 1440).We report the observation of discharge-pumped extreme ultraviolet lasing in collisionally excited ions of a material ablated from a solid target. Excitation of sulfur plasmas by a capillary discharge resulted in amplification of the J=0-1 line of Ne-like sulfur at 60.8 nm, with a gain coefficient of 0.45 cm-1 and a gain-length product of 7.5. Overheating of the electron temperature and transient population effects are computed to make a significant contribution to the measured gain

Generation of highly ionized cadmium plasma columns for a discharge-pumped Nickel-like Cd laser

Includes bibliographical references (page 574).We report the observation of strong line emission from Ni-like Cd ions in a capillary discharge plasma. Spectroscopically pure Cd vapor was produced in a room temperature environment utilizing a capacitive discharge. The metal vapor was injected into a capillary channel where it was subsequently excited with fast current pulses of up to 200 kA These results open the possibility of observing laser amplification in the 3d94d-394p line of Ni-like Cd at 13.2 nm and in laser lines of other Nickel-like ions in a discharge-created plasma

Spatial coherence measurement of a high average power table-top soft X-ray laser

Includes bibliographical references (page 126).An extraordinarily high degree of spatial coherence from a high average power tabletop 46.9 nm laser was observed in two-pinhole interference experiments. Refractive anti-guiding and gain guiding along a capillary discharge-produced plasma column causes a rapid increase of the spatial coherence with amplifier length. Full spatial coherence was approached with a 36 cm long plasma of very high axial uniformity and a length to diameter ratio exceeding 1000: 1

Demonstration of a discharge pumped table-top soft-x-ray laser

Includes bibliographical references (page 2195).Includes errata.We report the first observation of large soft-x-ray amplification (gl = 7.2) in a discharge-created plasma. A fast, ~40 kA, current pulse from a compact discharge was used to excite plasma columns up to 12 cm in length in 4-mm channels, producing population inversion in the J = 0-1 line of Ne-like Ar and resulting in a gain of 0.6 cm-1 at 46.9 nm. The beam divergence was measured to be <9 mrad

Discharge-driven 46.9-nm amplifier with gain-length approaching saturation

Includes bibliographical references.Gain length products up to gl ≈ 14 for the J = 0-1 line of Ne-like Ar at 46.9 nm have been achieved in 15-cm long plasma columns generated by a fast capillary discharge. Amplification in plasma columns up to 20 cm in length was investigated. The laser line intensity is observed to increase exponentially for plasma lengths of up to 15 cm, above which it is observed to saturate. The saturation behavior is discussed.This work was supported in part by the National Science Foundation under grants ECS-9401952 and ECS-9412106, and the U.S. National Research Council

Applications of high repetition rate tabletop soft X-ray lasers become a reality in several fields

Includes bibliographical references (page 468).For many years researchers have envisioned the development of compact high repetition rate tabletop soft x-ray laser, that could be routinely used in application in numerous disciplines. With demonstrated average powers of several mW and millijoule-level pulse energy at 46.9nm, the Ne-like Ar capillary discharge-pumped laser is the first compact laser to reach this goal. In this paper we summarize the development status of high repetition rate tabletop soft x-ray lasers based on capillary discharge excitation, and give examples of their successful use in several applications. Results of the use of a caprllary discharge pumped 46.9nm laser m dense plasma interferometry, soft x-ray reflectometry for the determination of optical constants, characterization of diffraction gratings, laser ablation of materials, and plasma generation are described. The observation of lasing at 52.9nm line in Ne-like Cl with output pulse energy up to 10 μJ is also reported

The Effect of Neutral Atoms on Capillary Discharge Z-pinch

We study the effect of neutral atoms on the dynamics of a capillary discharge Z-pinch, in a regime for which a large soft-x-ray amplification has been demonstrated. We extended the commonly used one-fluid magneto-hydrodynamics (MHD) model by separating out the neutral atoms as a second fluid. Numerical calculations using this extended model yield new predictions for the dynamics of the pinch collapse, and better agreement with known measured data.Comment: 4 pages, 4 postscript figures, to be published in Phys. Rev. Let

Enhanced beam characteristics of a discharge-pumped soft-x-ray amplifier by an axial magnetic field

Includes bibliographical references (pages 2477-2478).We report results of the study of soft-x-ray amplification in a discharge-created plasma under an externally applied axial magnetic field. This technique is observed to improve the uniformity and divergence of the beam of a 46.9-nm discharge-pumped Ne-like Ar soft-x-ray amplifier by decreasing the plasma density gradients at the time of lasing. At the optimum strength of 0.15 T, the magnetic field also causes an increase in the laser beam intensity. At higher fields the Zeeman effect is found to contribute to line broadening, decreasing the laser output