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Szewczak K.,Central Laboratory for Radiological Protection | Jednorog S.,Poland Institute of Plasma Physics and Laser Microfusion
Physica Scripta | Year: 2014

The Institute of Plasma Physics and Laser Microfusion operates the biggest plasma focus device built so far in the world. It is identified as DPF-1000 U (Dense Plasma Focus Upgrade). The plasma produced by the described device constitutes a pulse of highly effective neutron source with the neutron yield ranging up to 1012 n per impulse. The precise composition of the stainless steel from which the vacuum chamber of the plasma focus device is made, was determined by neutron activation analysis. It was found that nuclear reactions that occur inside the stainless steel are mainly (n, γ), (n, p) and (n, α) reactions. Taking into consideration the neutron energy spectrum and the material composition, 63 nuclear reactions leading to vacuum chamber material activation were identified in total. It was observed that in the first hour after shut-down, the main activity comes from 59Fe and 59Ni isotopes. One year after the shut-down, the main contribution to the observed radioactivity of the experimental chamber material was related to the presence of 54Mn isotope, while after 10 years the only significant contribution to the activity will be made by molybdenum isotopes such as 93mMo and 99Mo. © 2014 The Royal Swedish Academy of Sciences. Source

Szewczak K.,Central Laboratory for Radiological Protection | Jednorog S.,Poland Institute of Plasma Physics and Laser Microfusion
Central European Journal of Physics | Year: 2014

Plasma research poses a radiation hazard. Due to the program of deuterium plasma research using the PF-1000 device, it is an intensive source of neutrons (up to 1011 n · pulse -1) with energy of 2,45 MeV and ionizing electromagnetic radiation with a broad energy spectrum. Both types of radiation are mostly emitted in ultra-short pulses (∼100 ns). The aim of this work was to test and calibrate the RSS-131 radiometer for its application in measurements of ultra-short electromagnetic radiation pulses with broad energy spectrum emitted during PF-1000 discharge. In addition, the results of raw measurements performed in the control room are presented. © 2014 Versita Warsaw and Springer-Verlag Wien. Source

Badziak J.,Poland Institute of Plasma Physics and Laser Microfusion
Radiation Effects and Defects in Solids | Year: 2015

This paper summarizes briefly the main experimental and numerical results of the IPPLM team studies on the generation of ultra-intense ion beams by a short (≤1 ps) laser pulse. Basic laser-driven ion acceleration schemes capable of generating such ion beams are described including the target normal sheath acceleration (TNSA) scheme, the skin-layer ponderomotive acceleration (SLPA) scheme and the laser-induced cavity pressure acceleration (LICPA) scheme. It is shown that an efficient way for achieving high ion beam intensities and fluencies lies in using a short-wavelength laser driver of circular light polarization. In such a case, SLPA clearly dominates over TNSA, and dense and compact ion bunch is generated with high energetic efficiency. The LICPA scheme operating in the photon (radiation) pressure regime can be even more efficient than SLPA. As it is demonstrated by particle-in-cell simulations, the LICPA accelerator with a picosecond, circularly polarized laser driver of intensity ∼ 1021 W/cm2 can produce sub-picosecond light ion beams of intensity ∼ 1022 W/cm2 and fluence > 1 GJ/cm2 with the energetic efficiency of tens of percent. Laser-driven ion beams of such extreme parameters could open up new research areas in high-energy-density science, inertial fusion or nuclear physics. © 2015 Taylor & Francis. Source

Gribkov V.A.,Poland Institute of Plasma Physics and Laser Microfusion | Gribkov V.A.,RAS Institute of Metallurgy
Plasma Physics and Controlled Fusion | Year: 2015

The dense plasma focus (DPF) device represents a source of powerful streams of penetrating radiations (hot plasma, fast electron and ion beams, x-rays and neutrons) of ns-scale pulse durations. Power flux densities of the radiation types may reach in certain cases the values up to 1013W cm-2. They are widely used at present time in more than 30 labs in the world in the field of radiation material science. Areas of their implementations are testing of the materials perspective for use in modern fusion reactors (FR) of both types, modification of surface layers with an aim of improvements their properties, production of some nanostructures on their surface, and so on. To use a DPF correctly in these applications it is important to understand the mechanisms of generation of the above-mentioned radiations, their dynamics inside and outside of the pinch and processes of interaction of these streams with targets. In this paper, the most important issues on the above matter we discuss in relation to the cumulative hot plasma stream and the beam of fast ions with illustration of experimental results obtained at four DPF devices ranged in the limits of bank energies from 1 kJ to 1 MJ. Among them mechanisms of a jet formation, a current abruption phenomenon, a super-Alfven ion beam propagation inside and outside of DPF plasma, generation of secondary plasma and formation of shock waves in plasma and inside a solid-state target, etc. Nanosecond time-resolved techniques (electric probes, laser interferometry, frame self-luminescent imaging, x-ray/neutron probes, etc) give an opportunity to investigate the above-mentioned events and to observe the process of interaction of the radiation types with targets. After irradiation, we analyzed the specimens by contemporary instrumentation: optical and scanning electron microscopy, local x-ray spectral and structure analysis, atomic force microscopy, the portable x-ray diffractometer that combines x-ray single photon detection with high spectroscopic and angular resolutions, an x-ray microCT system with Cobra 7.4 and DIGIX CT software, microhardness measurements, etc. Some results in this area are presented. © 2015 IOP Publishing Ltd. Source

Barral S.,Poland Institute of Plasma Physics and Laser Microfusion | Peradzynski Z.,University of Warsaw
Physics of Plasmas | Year: 2010

The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations. © 2010 American Institute of Physics. Source

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