Optical measurements of the velocities of plasma pulses generated in the rod plasma injector J. Piekoszewski, J. Stanisawski, J. Baranowski, E. Skadnik–Sadowska, Z. Werner, M. Barlak The Andrzej Soltan Institute for Nuclear Studies, 05–400 Otwock– ´ Swierk, Poland J. Piekoszewski Institute of Nuclear Chemistry and Technology, Dorodna 16, 03–195 Warszawa, Poland Z. Werner Institute of Physical Chemistry PAS, Kasprzaka 44/52, 01–224 Warszawa, Poland Received 24 April 2004 Time–resolved optical spectroscopy is used to characterize plasma pulses generated in a Rod Plasma Injector type of machine. A time evolution of the lines corresponding to various ionization states of the working gas atoms is studied. The time–of–flight measurements combined with an analysis of plasma pulse interaction with a solid target permit a conclusion on the composition of the plasma pulse to be drawn. The plasma pulse is found to contain two components – a high– and a low–energy ones, produced by different acceleration mechanisms. PACS: 52.40.Hf Key words: plasma, pulse, spectroscopy 1 Introduction Over the past two decades several groups all over the world investigated applications of high–intensity pulsed ion (HIPIB) and high intensity pulsed plasma beams (HIPPB) to surface treatment of materials e.g. [1-5]. These techniques combine features of laser treatment and ion implantation, since both, heat and mass transfers occur in the “beam– target” system. Ion energy may range from a few keV to 1 MeV, pulse duration from 10 ns to 10 ms, and energy density from 0.01 to 50 J/cm 2 . One of the facilities capable to produce plasma pulses of energy density in the range of 1 ÷ 5J/cm 2 and pulse duration of about 1 μs is Rod Plasma Injector (RPI) [6]. With the use of RPI type generators a variety of surface properties of materials such as semiconductors, metals, and ceramics were beneficially modified by plasma beams e.g [7, 8]. The principle of operation of RPI was described elsewhere [6]. Briefly, the plasma pulse is generated as a result of a low–pressure, high–current discharge between two coax- ial, cylindrical sets of the rod–type electrodes. The discharge is initiated by applying a high voltage 30 ÷ 40 kV pulse after some delay time τ from a moment of the injection of the working gas into the inter–electrode space. RPI device produces single plasma pulses and Czechoslovak Journal of Physics, Vol. 54 (2004), Suppl. C C217