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Our investigations demonstrated that utilizing copper bromide (CuBr) mixture as a source of Cu atoms in a RF-excited discharge can be a promising alternative to the Cu sputtered system, when the development of Cu ion gas laser is considered. Both spectroscopic and laser investigations showed that the threshold input power for lasing was reduced about 5 times using the CuBr-based system instead of the Cu-sputtered system. Pulsed and CW laser oscillation on Cu+ transitions in the near IR spectral region was obtained in RF-excited He-CuBr discharge operated at 13.56 MHz and 27.12 MHz. At input RF power of 800 W, a laser output power of 10 mW at the 780.8 nm Cu ion laser line was achieved. An increase of laser output power by a factor of two, as well as better Cu vapour axial distribution and better discharge stability, was attained when DC discharge was superimposed on the RF discharge. Laser gain on 11 UV Cu ion lines was observed in RF-excited Ne-CuBr discharge. basing on the obtained results, we consider the CuBr laser system excited by RF discharge capable of generating UV laser radiation at relatively low input power. [ABSTRACT FROM AUTHOR]

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By the use of graphite cathodes in argon the normally unstable arc root exhibiting strong vaporization of the cathode can be made stationary with a well defined, axially symmetrical vapour jet. Spectroscopic measurements of the C molecular bands give a vapour temperature between 4000 K and 5000 K. On strongly heated electrodes the hot plasma is to some extent hindered by the relatively cold vapour: this results in a displacement, supported by magnetic forces, of the arc root onto colder areas and thus in instability. [ABSTRACT FROM AUTHOR]

The root of an argon are was stabilized by strong cooling of the graphite cathode; both the composition and the temperature of the plasma at the arc root were determined spectroscopically. The measurements of the absolute intensities of two CI and two CII lines revealed that the plasma is composed almost entirely of atomic carbon. Immediately in front of the cathode a temperature of 12000 K was measured and the degree to which the gas was ionized was found to be 30%. The velocity of the plasma was 300 m/s. [ABSTRACT FROM AUTHOR]

Arc roots at which marked vaporization occur are unstable and therefore in general non-stationary. High speed photography of arc roots using various electrode materials in Ar, SF, and N shows that the appearance of the arc roots results from the superposition of several phenomena. On graphite cathodes in Ar it was possible to observe these phenomena separately by varying the cooling of the electrodes. It is shown that distinctions must be drawn between the real current transfer region with relatively weak vaporization, vaporization from the electrode surface outside this region and vaporization from within the body of the electrode. The energy-balance determined experimentally confirms the theoretical prediction that the energy for strong vaporization of the cathode is supplied by an ioncurrent. [ABSTRACT FROM AUTHOR]

The diffraction theory of image construction has been used, in the case of a differential interferometer employing a Wollaston prism, to derive the position of the interference fringes in dependence upon the phase object and the prism position. This procedure is not only more correct, but proves also to be simpler than the corresponding geometric-optical treatment. An example is presented in which the fringe shift resulting from a symmetrical gas flow has been used to evaluate the gradient of the optical path perpendicular to the rotational axis of symmetry. [ABSTRACT FROM AUTHOR]

Experimental and theoretical investigations have been performed to determine the thermal conductivity of hydrogen in the temperature range between 2000 and 7000 °K. For this purpose the radial temperature distributions for various currents and the E-I-characteristic of a low current wall-stabilized hydrogen arc have been measured. In the dark region of the arc outside the bright core the temperature and the thermal conductivity between 2000 and 4500 °K were found by means of the schlieren technique. The electron temperature in the core of the arc results from spectroscopic measurements. The gas temperature has been calculated with a formula, derived from the kinetic theory of gases. Assuming a constant collision integral Q the radial distribution of electric conductivity has been calculated according to Langevin's formula. The value Q=30·10 cm results by comparing the integrated conductance with the measured one. Since now the radial distribution of power input and the temperatures are known, the thermal conductivity between 4500 and 7000 °K can be determined as well. The total course of the heat conductivity shows a strong peak at the temperature of 3740 °K characteristic for the dissociation process. [ABSTRACT FROM AUTHOR]

The onset current of the helical instability of wall stabilized arcs can be determined by a theoretical model from a dimensionless function which is only dependent on the power input and a factor containing the gas properties and the arc conductance. The model describes the onset current of the instability in hydrogen and nitrogen as function of the tube diameter and of the pressure. Questions of restabilization are discussed. [ABSTRACT FROM AUTHOR]