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1

Measurements of fast electron beams and soft X-ray emission from plasma-focus experiments

Surała W., Sadowski M. J., Kwiatkowski R., Jakubowski L., Żebrowski J.

Nukleonika

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2016

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Vol. 61, No. 2

161--167

EN

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 modifi ed 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 fi lling, many strong electron signals were recorded in all the measuring channels. Those signals were well correlated with the fi rst 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 confi rmed 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 fi lms, showed the appearance of some fi lamentary 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.

2

Recent measurements of soft X-ray emission from the DPF-1000U facility

Surała W., Sadowski M. J., Paduch M., Zielinska E., Tomaszewski K.

Nukleonika

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2015

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Vol. 60, No. 2

303--308

EN

Soft X-ray imaging is a very useful diagnostic technique in plasma-focus (PF) experiments. This paper reports results of four experimental sessions which were carried out at the DPF-1000U plasma-focus facility in 2013 and 2014. Over 200 discharges were performed at various experimental conditions. Measurements were taken using two X-ray pinhole cameras with a line of sight perpendicular to the z-axis, at different azimuthal angles (about 20° and 200°), and looking towards the centre of the PF-pinch column. They were equipped with diaphragms 1000 μm or 200–300 μm in diameter and coated with filters of 500 μm Al foil and 10 μm Be foil, respectively. Data on the neutron emission were collected with silver activation counters. For time-resolved measurements the use was made of four PIN diodes equipped with various fi lters and oriented towards the centre of the PF-column, in the direction perpendicular to the electrode axis. The recorded X-ray images revealed that when the additional gas-puff system is activated during the discharge, the stability of the discharge is improved. The data collected in these experiments confi rmed the appearance of a filamentary fi ne structure in the PF discharges. In the past years the formation of such fi laments was observed in many Z-pinch type experiments. Some of the recorded X-ray images have also revealed the appearance of the so-called hot- -spots, i.e. small plasma regions of a very intense X-ray emission. Such a phenomenon was observed before in many PF experiments, e.g. in the MAJA-PF device, but it has not been investigated so far in a large facility such as the DPF-1000U. The time-resolved measurements provided the evidence of a time lapse between the X-ray emission from plasma regions located at different distance from the anode surface. The formation of distinct ‘hot-spots’ in different instants of the DPF-1000U discharge was also observed.

3

An analysis of the elemental composition of micro-samples using EDS technique

Wassilkowska A., Czaplicka-Kotas A., Zielina M., Bielski A.

Czasopismo Techniczne. Chemia

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2014

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R. 111, z. 1-Ch

133--148

EN

A classic example of the application of electron-dispersive spectroscopy (EDS) is the observation of the microstructure of solid samples using scanning electron microscope (SEM). This provides the possibility of taking measurements of chemical composition in very small areas. Measurements can be performed on any bulk sample through adjusting the X-ray excitation parameters to the elements of its expected composition. Examples of the applications of the EDS technique in the context of environmental engineering have been presented.

PL

Obserwacje mikrostruktury litych próbek przy użyciu skaningowego mikroskopu elektronowego (SEM) z możliwością wykonania lokalnego pomiaru składu chemicznego w bardzo małym obszarze, to klasyczny przykład zastosowania spektroskopii dyspersji energii (EDS). Pomiar wykonywany jest na dowolnej próbce stałej, stosując parametry wzbudzenia promieniowania rentgenowskiego adekwatne do pierwiastków, spodziewanych w składzie próbki. Omówiono przykłady zastosowania techniki EDS w zagadnieniach związanych z inżynierią środowiska.

4

Exploitation of the universe with regard to controlled thermonucIear fusion reaction of the sun

Ghosh S. K.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 2

571-573

EN

A physical interpretation of relevance to a mathematical argument is the determination of the reality of the universe by applying a radio frequency accelerator with the Sun. The exploitation of the universe deals with the controlled thermonuclear fusion reaction of the Sun at the re sonant level to produce X-ray ernission subject to an irregular fluctuation of a magnetic field in vacuum.

5

Reproducibility conditions for the pulsed X-ray emission in a vacuum spark discharge

Georgescu N., Serbãnescu C. G., Sandolache G.

Nukleonika

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2001

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Vol. 46, suppl. 1

17--20

EN

In our laboratory, a 1 kJ vacuum spark device is developed as a pulsed X-ray source for X-ray detector calibration and applications such as X-ray microscopy and microlithography. After our previous works for the X-ray emission maximization (up to around 10 J per pulse), this paper analyses the influence of four different triggering systems on the X-ray emission reproducibility. The main conclusion is that a high-power, very fast high voltage trigger pulse is required. In order to fulfill these conditions, a pulse transformer and an air spark gap have been added to the initial triggering device (a magnetic pulse compression circuit). With the new trigger pulse (20 J/pulse, 50 ns rise-time, 22 kV amplitude in an open circuit) a reasonable X-ray emission reproducibility is obtained.