A. M. Yancharina

Influence of inert and molecular gas impurities on the lasing efficiency of a neon-hydrogen plasma laser operating at λ=585.3 nm He

A study has been made of the effect that inert and molecular gas impurities (He, Ar, Kr, Xe, N2, CO2) have on the lasing efficiency of a Penning plasma laser operating at λ=585.3 nm Hel in an Ne-H2 mixture excited in a longitudinal discharge. The optimal compositions found for ternary mixtures can substantially increase the laser output parameters. The lasing power gain obtained in an Ne-H2-Ar mixture is more than an order of magnitude higher than that in an Ne-H2 mixture.

Investigation of the active media in pulsed gas discharge lasers by the Rozhdestvenskii hook method

In this review we generalize the results of our experimental investigations in which the Rozhdestvenskii hook method was first used to look for an inverted population in new spectral transitions. An inverted population in new 3p–3s transitions of the neon atom with λ=588.1, 594.4, 650.6, and 653.2 nm was discovered in the active medium of a Penning plasma laser emitting the λ=585.3 nm neon line in Ne-H2 and Ne-H2-Ar mixtures. Results of investigations of a number of active media are given. An analysis is made of the spatial and temporal distributions of copper atoms in the ground state and of their influence on the lasing efficiency of a copper-vapor laser. Using the rhenium atom as an example, it was shown to be possible to obtain a sufficiently high concentration of refractory metal atoms (>1014 cm−3) in an active medium to form active media of lasers utilizing self-terminating transitions and also plasma lasers.

Optical diagnostics of dispersing He plasma

An experimental study has been made of the characteristics of radiation from a dispersing helium plasma. From measurements of the space-time dependence of the line intensities of the helium 23P — n3D series we obtained the distribution of the populations of the n3D levels for n=3−10. The study has shown that over a wide range of conditions the high-lying levels (n=5−10) are in equilibrium with electrons while a substantial deviation from equilibrium is observed for levels n=3, 4. From the energy distribution of the populations of the upper levels we determined the space-time dependence of the electron temperature, which reflects the process of effective electron cooling during dispersal of the plasma. The gas temperature was estimated from the populations of helium singlet and triplet levels with n=5. The time distribution of the electron density in the plasma was found from the Stark broadening of the spectral lines.

Pulsed plasma source of refractory metals

A pulsed plasma source of metal vapors is proposed, including refractory metals. The potentials of this source are illustrated on atomic rhenium, for example. A spectroscopic investigation of the spatial and temporal characteristics of the radiation arid the plasma parameters is conducted for a Re-He mixture. It is shown that the source permits one to realize a plasma over a wide range of parameters. In the spatial zone above the electrodes, the temporal evolution of the concentration distribution of Re atoms in the ground state is measured. A maximum value of 5·10+14 cm−3 is achieved.

Cadmium ion excitation in an expanding He-Cd plasma

Space-time characteristics of radiation, temperature, and electron concentration are studied for segmented excitation and subsequent recombination in an expanding He-Cd plasma. It is shown that recombination processes play the dominant role in excitation of levels. The collision of metastable helium and cadmium atoms is significant in populating the cadmium ion 42F5/2, 7/2 levels.

Level population by recombination in a pulsed plasma jet in an He-Xe mixture

Measurements have been made on the spatial and time characteristics of the radiation from an He-Xe plasma jet emerging from a discharge channel through a nozzle with a speed of about 105 cm/sec. A recombination mechanism is indicated for the line excitation by the delay between the current pulse and the production of the radiation, as well as by the substantial differences in time course for the intensities of the atomic and ionic lines and by the increase in intensity with pressure. Measurements have been made of the electron temperature and concentration, and estimates have been made of the recombination coefficients, which reflect the performance of the collisional-radiative recombination in a decaying He-Xe plasma jet.

Calculation of the quadratic stark effect in krypton

The quadratic Stark effect for the seventeen levels of krypton in the 4s2p5ns-, 4s2p5np- and 4s2p5nd -configurations is calculated in the Coulomb approximation. The calculation is conducted for j-l and j-j coupling. The results obtained are found to agree satisfactorily with experiment. The Stark effect constants are given.

Calculation of the Stark splitting for some levels of xenon

In the second approximation of the perturbation theory, the computation of the quadratic Stark effect was carried out for the number of 2pand 3p-levels of xenon. There are no wave functions for the excited states of xenon, which makes the theoretical estimation of the Stark constants difficult. Calculation of the Stark splitting of xenon levels was carried out in Coulomb approximation by making use of the Bates and Damgaard tables [i]. The calculations make possible, firstly, the theoretical estimation of the constants of the Stark effect, and secondly, the clarification of the nature of excitation of energy levels in the electric field. Calculation of splitting of the 3pc level makes it possible to explain the Stark effect of the spectral lines h 4624 ~ (3pG-ISs) , and ~ 4843 A (3pG-is4) which is relatively large as experimentally observed. In the field occurs splitting of the 3pG level into three sublevels, resulting from excitation of the near-by 4d 3 level. Similar estimation of the Stark constants can be performed for a number of othei: heavy elements.