E A Yukov

Density-Dependent Lines of One- and Two-Electron Ions in Diagnostics of Laboratory Plasma. II. Intensity Line Ratios of Hydrogenlike, Heliumlike and Oxygenlike Multicharged Ions

Density-dependent spectral lines play an important role in the plasma physics research. Such lines can be used for determination of plasma density from the ratio of spectral line intensities. In the preceding paper [1] we have considered the inelastic collisional transitions between close ion levels which are responsible for excited state distribution when it changes from coronal model at low electron densities up to Boltzman distribution at high electron densities. This variation is the reason of the density dependence of spectral line intensity ratios. In this paper basing on the results obtained in [1] the ratios of several spectral lines of H, He and O-like ions are plotted as a function of electron density. The regions of the plasma parameters for which this ratio may be used as a diagnostics tool are found. The results of this work makes it possible to diagnose plasmas (laser and electron beam plasma, exploding wires, plasma focus etc.) for electron densities 1018 < Ne < 1023cm-3.

The observation of intercombination lines 1s3p 3P1→1s2 1S0 of multicharged He-like ions in laser-produced plasmas

The intercombination lines 1s3p 3P1 to 1s2 1S0 of the ions Mg XI, Al XII, P XIV, S XV and Cl XVI have been observed for the first time in the spectra of laser-produced plasmas. The wavelengths and relative intensities of such lines were measured. The identification of the observed lines was carried out by means of a comparison of the experimental wavelengths and intensities with the theoretical ones. The dependence of the relative intensities of such lines on the plasma parameters was investigated.

Anomalous intensity ratios of the resonance to intercombination lines of He-like ions in Nd- and CO2-laser-produced plasmas

Anomalously small values of the intensity ratio alpha of resonance and intercombination lines of He-like ions have been observed in Nd- and CO2-laser-produced plasmas. The values of alpha obtained are explained via calculations using a non-stationary ionisation model for the plasma (overheated for CO2-laser plasma, and supercooled for expanding Nd-laser plasma). The measurements of the intensity ratio may be used to obtain information on the relative concentrations of H-, He-, and Li-like ions in the plasma. The results obtained allow one to answer the questions: when must the non-stationary character of the plasma ionisation state be taken into account for the observed spectra to be interpreted correctly; and when can one use more simple stationary models for the plasma concerned?.

Measurements of electron density in laser-produced plasmas from the XUV spectra of oxygen-like ions

Electron densities in laser-produced plasmas have been deduced from space-resolved spectra of oxygen-like ions Ca XIII, Ti XV, Fe XIX, Ni XXI and Cu XXII in the XUV (80-170 AA). The transition 2p6 1S0 to 2s2p5 1P1 has been identified for Cu XXII, the wavelength of the same transition for Ni XXI has been defined more precisely. Plasma images in the light of the different spectral lines have yielded the dimensions of the spatial regions in which Ca XIII, Fe XIX and Ni XXI exist.

High-power Ti:sapphire lasers for optical polarization of 3He

A current status and perspectives of the work on a high density polarized 3He target are reported. The problems of high-power laser design for optical pumping are discussed. A general formulation for the analysis of an arbitrary linear resonator with internal lens of variable focal length, which represents the rod of a solid-state laser is presented. It is shown that mode spot size is stable with respect to lens optical power fluctuations in one part of resonator when it reaches a minimum on a laser rod. The rules for the design of stable resonators with two or more variable lenses are proposed.

Possibility of using recombination reactions and alkali metals to obtain inversion on atomic iodine

The possibility of producing a continuous-flow laser operating on an atomic iodine transition is considered. Population inversion is the result of depletion of the lower laser level on account of predominant recombination into iodine molecules in the ground state. Alkali-metal atoms are used to obtain atomic iodine and free radicals without consumption of electric energy. The use of an electric discharge is proposed for the excitation of atomic iodine. The kinetics of the basic chemical reactions is considered and the possibility is demonstrated of obtaining inversion at reasonable working-mixture parameters. The schematic diagram of the laser setup is discussed.

Possible use of alkali metals to obtain population inversion in atomic iodine

The possibility of population inversion of the 52P1/2 and 52P3/2 levels in atomic iodine as a result of a fast recombination reaction between the atomic iodine and radicals R (such as CF3 and C3F7) is discussed. The proposed method is based on the experimentally observed difference between the reactivity of the iodine atoms in the ground 52P3/2 and excited 52P1/2 states in various recombination reactions. In this type of laser, an important part is played by the alkali metal which is the chemical source of free radicals and iodine atoms. Numerical calculations are made using a kinetic model of the proposed laser. The main design parameters of a feasible iodine recombination laser are estimated.