31 st ICPIG, July 14-19, 2013, Granada, Spain Spectroscopic investigations of electric arc plasma with additions of copper and molybdenum A. Veklich, A. Lebid, T. Tmenova, V. Boretskij Taras Shevchenko Kiev National University, Radio Phys. Dept., 64, Volodymirs’ka Str., Kiev, 01033, Ukraine The aim of this work is determination of plasma parameters of electric arc discharge between Cu-Mo composite electrodes in argon flow. The radial profiles of plasma temperature and electron density, obtained by optical emission spectroscopy, were used in calculation of plasma composition in assumption of local thermodynamic equilibrium. It was found that ionization of copper and molybdenum components have comparable contribution in plasma channel conductivity. Additionally Boltzmann plot method was used, as convenient instrument for analysis and selection of MoI spectral lines and their spectroscopic data. In result of such procedure oscillator strength of several MoI spectral lines are recommended. Introduction Composite materials on copper base with addition of high-melting metals, particularly molybdenum, have advanced electric and exploitation characteristics. They have applications as materials for switching devices’ contacts [1] and sliding contacts for mine slow-speed railway [2]. Arc discharges appear during operation of these devices and interact with electrodes material, so injection of electrode material into discharge gap has place. Therefore investigation of electric arc plasma between such composite electrodes can be useful for further optimization of contact materials. Additionally, analysis of Mo atomic spectral lines in visible spectral range for the purpose of spectroscopic applications was performed. 1. Experimental conditions and setup The arc was ignited in argon flow 6.4 slpm between the end surfaces of Cu-Mo non-cooled electrodes. The discharge gap was 8 mm, arc current was 3.5 and 30 A. To avoid the metal droplet appearing, a pulsing high current mode was used: the current pulse 30 A was put on the "duty" low- current (3.5 A) discharge. The high-current pulse duration was 30 ms. Cu-Mo composite electrodes fabricated by electron beam evaporation and following condensation in vacuum were used [2]. These electrodes have layered structure, content of molybdenum changes from layer to layer in range 1%-20%; average content of molybdenum was 12%. Technique of one-pass tomographic recording of the spatial distribution of spectral line intensities was used [3]. Appropriate experimental scheme is shown in Fig.1. Monochromator MDR-12 with 3000-pixels CCD linear image sensor Sony ILX526A (B/W) accomplished fast scanning of spatial distribution of radial intensity. Due to the instability of the discharge, statistical averaging of the recorded spatial distributions of the radiation characteristics was carried out. Because side-on (lateral) observation of plasma object was realized in proposed experimental setup, it is necessary to use Abel inversion [4] for obtaining of local values of intensity. Fig. 1 Registration of spatial distribution of spectral line intensities 11