Cw recombination laser in a flowing negative glow plasma

Includes bibliographical references (page 1147).cw laser oscillation has been obtained in the 1.43-μm line of Cd I populated by electron-ion recombination in the flowing afterglow of a negative glow plasma. The metal vapor in there combining plasma is produced at room temperature by cathode sputtering. Negative glow plasmas having an electron energy distribution in which energetic beam electrons and supercooled secondary electrons coexist under steady-state conditions are shown to be an attractive medium for the excitation of cw recombination lasers

Temporal evolution of plasma from a highly ionized helium capillary discharge

Includes bibliographical references (page 788).Emission spectroscopy was used to study the temporal evolution of a highly ionized helium plasma generated in a 1-mm-diameter capillary by a fast (90-ns full width at half-maximum (FWHM)) discharge pulse. The time dependence of the plasma density was measured from the Stark broadened line profile of the HeII 468.5-nm transition. A 1.2-kA discharge current pulse was observed to create a plasma density of 8 × 1016 cm-3 in 1 torr of helium. The maximum intensity of HeII transitions occurs in the afterglow of the discharge pulse, following the collisional recombination of totally stripped ions with plasma electrons when the plasma cools. The study is of interest in relation to the possibility of obtaining amplification in the 164.0-nm line of HeII in a capillary discharge

Classification of the nickel-like silver spectrum (AgXX) from a fast capillary discharge plasma

Includes bibliographical references (page 25).A study of the Ni-like silver (AgXX) spectra in the 13:7-20:5 nm wavelength region using a plasma generated by a fast high power capillary discharge is reported. Forty-three AgXX transitions have been identified with the assistance of calculations performed using the Slater-Condon method with generalized least-squares fits of the energy parameters. The average difference between the measured transition wavelengths and the theoretical values is 0.0026 nm

Beam optics of gain-guided soft-x-ray lasers in cylindrical plasmas

Includes bibliographical references (page 2851).We analyze soft-x-ray beam propagation and amplification in gain-guided amplifiers of cylindrical geometry for arbitrary gain and density profiles. A general relation that must be fulfilled for refraction not to be an impediment to the exponential growth of the intensity is obtained. It is shown that for sufficiently long plasma columns the effective gain, reduced by refraction, is determined solely by the gain and the curvature of the density profile at the position of maximum density, even when the location of the gain and the density maxima do not coincide. We analyze the case of amplifiers with gain-length approaching saturation and show that refraction reduces the effective gain-length product at which gain saturation occurs. The theoretical results are used to analyze the output of a capillary discharge soft-x-ray laser

Effect of an axial magnetic field on the spontaneous emission from an argon hollow cathode discharge, The

Includes bibliographical references (page 122).An applied longitudinal magnetic field is observed to decrease the equilibrium population of excited argon ion levels in a hollow cathode discharge, whereas the excited state populations of neutral argon atoms are not significantly altered. The longitudinal magnetic field is shown to decrease the effective density of beam electrons in the negative glow

Zn II and As II CW laser transitions excited by an electron beam

Includes bibliographical references (page 1054).CW laser action was obtained on the 4911.6, 4924.0, 6102.5, and 7588.5 Å transitions of Zn II and on the 6511.7 Å transition of As II using electron beam excitation of He-Zn and He-As mixtures, respectively

Light collection and wavelength calibration for an extreme ultraviolet diode array spectrograph

Includes bibliographical references.We describe the use of a simple spherical aluminum-coated mirror to image the radiation of a distant XUV-emitting plasma in the slit of a vacuum spectrograph. Calculations to determine the optimum position and curvature radius of the mirror as a function of the divergence of the emitted plasma radiation are described, Efficient light collection by the grazing incidence mirror allows calibration of an intensified diode array used as a detector with a low-pressure (10-4 Torr) dc capillary discharge that does not require a complex differential pumping system.This work was supported by the National Science Foundation Grant No. ECS 8606226. M. C. Marconi was supported by a fellowship from Universidad Nacional de Buenos Aires and Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina

Origin of photoluminescence signals obtained by picosecond-excitation correlation measurements

Includes bibliographical references (page 14355).We have developed a theory that explains the spectral distribution and the different time decay behaviors of the signals observed in picosecond excitation-correlation measurements of semiconductor materials. The results display good quantitative agreement with experiments on multiple quantum wells and show that band filling has an important role in determining the characteristics of the correlation signals. Two limit cases are found and mathematically characterized: the nondegenerate regime, where the signals are positive with exponential-like decays, and the degenerate regime, where band filling gives rise to negative signals. It is shown that the technique is a sensitive probe of the carrier dynamics not fully exploited in previous work

Fast gating of a windowless dual-multichannel-plate intensified array detector

Includes bibliographical references (pages 851-852).A technique for rapid gating of the gain of a windowless dual-multichannel-plate-intensified array detector is described. A DC bias applied to the plates allows effective switching of the gain with a relatively low-voltage (500 V) pulse. The pulse is generated by discharging 50 Ω transmission lines through a single fast MOSFET. The pulser characteristics and the dependence of the intensifier sensitivity on the applied voltage are discussed. The apparatus was used to obtain time-resolved extreme ultraviolet spectra with an optical aperture time of about 5 ns