The results are presented of the optical spectra measurements for free plasma streams generated with the use of the modified DPF-1000U machine. This facility was recently equipped with a gas injection system (the so-called gas-puff) placed on the symmetry axis behind the central opening in the inner electrode. The DPF-1000U experimental chamber was filled up with pure deuterium at the initial pressure of 1.6 or 2.4 mbar. Additionally, when the use was made of the gas-puff system about 1 cm3 of pure deuterium was injected at the pressure of 2 bars. The gas injection was initiated 1.5 or 2 ms before the triggering of the main discharge. The investigated plasma discharges were powered from a condenser bank charged initially to 23 kV (corresponding to the energy of 352 kJ), and the maximum discharge current amounted to about 1.8 MA. In order to investigate properties of a dense plasma column formed during DPF-1000U discharges the use was made of the optical emission spectroscopy. The optical spectra were recorded along the line of sight perpendicular to the vacuum chamber, using a Mechelle®900 spectrometer. The recent analysis of all the recorded spectra made it possible to compare the temporal changes in the electron density of a freely propagating plasma stream for discharges without and with the gas-puffing. Using this data an appropriate mode of operation of the DPF-1000U facility could be determined.
1. Scholz, M., Drozdowicz, K., Karpinski, L., Krauz, V., Kubes, P., Paduch, M., Pisarczyk, T., Sadowski, M. J., Kurowski, A., Igielski, A., Dankowski, J., Woznicka, U., Janik, W., Czaus, K., Malinowski, K., Kwiatkowski, R., Skladnik-Sadowska, E., & Zebrowski, J. (2013). Status of Plasma-Focus rese arch in Poland. In Proceedings of the International Conference PLASMA-2013, 2–6 September 2013 (T10). Warsaw, Poland.
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