The paper reports results of the recent experimental studies of pulsed electron beams and soft X-rays in plasma-focus (PF) experiments carried out within a modified PF-360U facility at the NCBJ, Poland. Particular attention was focused on time-resolved measurements of the fast electron beams by means of two different magnetic analyzers, which could record electrons of energy ranging from about 41 keV to about 715 keV in several (6 or 8) measuring channels. For discharges performed with the pure deuterium filling, many strong electron signals were recorded in all the measuring channels. Those signals were well correlated with the first hard X-ray pulse detected by an external scintillation neutron-counter. In some of the analyzer channels, electron spikes (lasting about dozens of nanoseconds) and appearing in different instants after the current peculiarity (so-called current dip) were also recorded. For several discharges, fast ion beams, which were emitted along the z-axis and recorded with nuclear track detectors, were also investigated. Those measurements confirmed a multibeam character of the ion emission. The time-integrated soft X-ray images, which were taken side-on by means of a pinhole camera and sensitive X-ray films, showed the appearance of some filamentary structures and so-called hot spots. The application of small amounts of admixtures of different heavy noble gases, i.e. of argon (4.8% volumetric), krypton (1.6% volumetric), or xenon (0.8% volumetric), decreased intensity of the recorded electron beams, but increased intensity of the soft X-ray emission and showed more distinct and numerous hot spots. The recorded electron spikes have been explained as signals produced by quasi-mono-energetic microbeams emitted from tiny sources (probably plasma diodes), which can be formed near the observed hot spots.
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1. Sadowski M. Herold H. Schmidt H. & Shakhatre M. (1984). Filamentary structure of a pinch column in plasma focus discharges. Phys. Lett. A 105 117-123.
2. Bernard A. Bruzzone H. Choi P. Chuaqui H. Gribkov V. Herrera J. Hirano K. Krejci A. Lee S. Luo C. Mezzetti F. Sadowski M. Schmidt H. Ware K. Wong C. S. & Zoita V. (1998). Scientific status of plasma focus research. J. Moscow Phys. Soc. 8 93-170.
3. Scholz M. Sadowski M. & Szydlowski A. (1999). Studies of the x-ray emission from high-current discharges performed in PF-1000 facility at different operational conditions. J. Tech. Phys. 40(Suppl. 1) 113-116.
4. Jakubowski L. & Sadowski M. J. (2002). Hot-spots in plasma-focus discharges as intense sources of different radiation pulses. Brazil. J. Phys. 32 187-192.
5. Skladnik-Sadowska E. Baranowski J. Sadowski M. & Zebrowski J. (2002). X-ray and corpuscular emission from different plasma discharges of axial symmetry. J. High Temp. Mat. Proc. 6 23-34.
6. Zebrowski J. Sadowski M. J. & Jakubowski L. (2004). Studies of electron beams and x-rays within different plasma-focus devices. Czech. J. Phys. 54(Suppl. C) C256-C263.
7. Zebrowski J. Sadowski M. J. Czaus K. Paduch M. & Tomaszewski K. (2004). Peculiar features of plasma-focus discharges within PF-360 facility. Czech. J. Phys. 54 643-659.
8. Scholz M. Paduch M. Tomaszewski K. Stepniewski W. Bienkowska B. Ivanova-Stanik I. Karpinski L. Miklaszewski R. Sadowski M. J. Jakubowski L. Skladnik-Sadowska E. Szydlowski A. Malinowska A. Kubes P. Kravarik J. Barvir P. Klir D. Tsarenko A. & Schmidt H. (2006). Recent results of MJ plasma- -focus experiment. AIP Conf. Proc. 808 207-210. http://dx.doi.org/10.1063/1.2159354.
9. Sadowski M. J. & Scholz M. (2008). The main issues of research on dense magnetized plasmas in PF discharges. Plasma Sources Sci. Technol. 17 024001.
10. Kubes P. Klir D. Kravarik J. Rezac K. Paduch M. Pisarczyk T. Scholz M. Chodukowski T. Bienkowska B. Ivanova-Stanik I. Karpinski L. Sadowski M. J. Tomaszewski K. & Zielinska E. (2012). Energy transformation in column of plasma-focus discharges with MA currents. IEEE Trans. Plasma Sci. 40(2) 481-486.
12. Surala W. Sadowski M. J. Paduch M. Zielinska E. & Tomaszewski K. (2015). Recent measurements of soft X-ray emission from the DPF-1000U facility. Nukleonika 60(2) 303-308.
13. Sadowski M. J. Paduch M. Skladnik-Sadowska E. Surala W. Zaloga D. Miklaszewski R. Zielinska E. & Tomaszewski K. (2015). Soft x-ray studies of plasma-focus pinch structures in PF-1000U experiments. Plasma Sources Sci. Technol. 24 055003.