[en] The measurement results are presented of plasma electron-concentration and discharge symmetry in the Focus device. The measurement have been performed by the methods of laser diagnostics. (author)

[en] The paper summarizes theoretical and experimental research curried out by the IPPLM team within the CRP Programme ‘Conceptual development of steady-state compact fusion neutron sources’. The aim of the activities reported here was to demonstrate that construction of the compact, pulsed, high neutron yield generator based on the Plasma-Focus concept is feasible. To realize the goals of the project the following tasks have been carried out: analysis of the experimental and theoretical scaling laws, preparation of the appropriate numerical codes to be used to select the most promising configuration of the PF based neutron generation, etc. The extensive experimental program performed on the Plasma-Focus PF–1000 accompanied the theoretical part of the research with the aim of identification of possible methods to enhance the neutron yield from the PF neutron generators. Finally, numerical simulation allowed to examine ~10⁶ configurations for assumed PF with 10 MJ stored energy, 150 kV charging voltage and to show, that according to the scaling laws, such optimized configurations should ensure the neutron yield 10¹⁶–10¹⁷ neutrons/discharge. (author)

[en] Determination of the electron density of plasma generated in a great plasma focus device by means of interferometry is very difficult or sometimes impossible. In order to determine spatial electron density distributions of plasma at the PF-1000 device, the special method was prepared. with the use of plasma images obtained by means of both an optical frame camera and shadowgraphy. Analysis of plasma radiation in the very narrow (Δλ = 60 A) optical range allows to determine the relation between an intensity of the plasma radiation and the electron density. It was also shown, that an influence of electron temperature on the plasma radiation is not large. The presented method allowed ono to obtain the spatial electron density distributions of plasma (in arbitrary units) at the PF-1000 device. By means of this method a number of important information about the plasma-focus phenomenon were obtained. (author)

[en] A brief history of investigation carried out on the PF-150 plasma-focus device is presented. Essential results concerning the dynamics of plasma sheath are summarized. The present state of investigation and main areas of interest are shown. (author)

[en] The paper presents results of studies of the behaviour of a laser-produced plasma in strong external axial and transverse magnetic field of 5-20 T in induction generated from a flat teflon target at the laser power densities of about 10¹⁴ W cm^-2. The investigations were carried on by means of a three-frame interferometry and a non-contact magnetic probe, so called remote magnetic probe (RMP). The dynamics of the process of creation of the diamagnetic cavity, its shape and dimensions have been determined. Computer simulation of plasma expansion by 2-D MHD code was made. (authors)

[en] A development of the polarimeter system for measuring the azimuthal magnetic field in the plasma focus (PF) device is presented. Measurements were carried out on the PF-360 device by means of the Faraday rotation (FR) method. It was concluded that current-driven instability of plasma does not cause enhanced diffusion of the magnetic field to the moment when the MHD m=0 instability of the plasma column is observed. (author)

[en] The paper presents results of formation of expanding plasma by combining laser-produced plasma with an external strong magnetic field. The plasma was generated by means of a Nd-glass laser which was focused on a solid target located on the axis of a single-turn coil providing magnetic field of up to 50 T. Spatial characteristics of the dynamics of interaction of the plasma with the magnetic field were registered by means of a three-frame interferometry. For registration and analysis of interferograms, CCD cameras and a multichannel image acquisition system were used. An interesting influence of the strong magnetic field on the plasma dynamics and shape was observed. Preliminary results of numerical modelling are compared with the experimental data. copyright 1996 American Institute of Physics

[en] A special experimental arrangement developed for the plasma-focus PF-1000 device studies is presented in this paper. It consists of high-bandwidth acquisition system for transient electrical signals registration, high-speed image-capturing system for registration of plasma images in different spectral range, and synchronization system. Some examples are given of the results obtained by means of this arrangement during experiments performed on the PF-1000 device. (author)

[en] The paper presents results of investigations and the analysis of the behaviour of a laser-produced plasma in a strong external magnetic field. The studies were carried out for a plasma generated from a planar teflon target irradiated with a neodymium laser beam of the power density of 10¹⁴ W/cm². Magnetic fields of 5 T up to 15 T in induction and a force-lines geometry parallel to the laser heating beam direction were used. A three-frame laser interferometry was used for the study of the plasma column formation and the disintegration process. The interferometric system was illuminated with a Nd laser beam (λ = 1.06 μm). Two kinds of plasma creation were observed in the external magnetic field, i.e., angular and axial expansion, related to the target illumination conditions. In the case of the angular expansion, a characteristic plasma configuration called ''horseshoe'' was observed again. Interaction of such configuration with the external magnetic field results in formation (at t > 25 ns) of a plasma cylinder of about 1 mm in length and with the external radius equivalent to the plasma magnetic confinement radius (R_B ∼ B^-2/3₀). In the case of axial expansion, the plasma concentrated on the axis has the longest lifetime as in the case of free expansion (B₀ 0). (orig.)

[en] Both the forming and decay stages of dense pinch in the PF-300 device of energy up to 360 kJ were investigated by means of four-frame shadow photography. A streak camera and standard diagnostics neutron and electrical measurements were applied as well. The characteristic times and velocities in the course of PF phenomenon, the dimensions of plasma sheath and pinch were also measured. The high neutron yield was connected with the thin and homogenous plasma sheath, minimum radius of the pinch about 2.5mm and short duration of the expansion and decay of one. It was also observed a MHD instability of the plasma sheath during its collapse in form-of two distortions. Theoretical investigations confirm such instability may appear. In some cases an anomalous structure of the plasma sheath was observed, when it was delaminated. One may conclude it was due to non-classical development of the MHD instability. Besides, a very low neutron yield was registered in such discharges. The streak camera photos made perpendicular to symmetry axis showed two luminous areas in visible range. The first one appeared in the moment of maximum compression, and its duration was only 30 ns when the neutron yield was high. It was observed the shorter time interval between the two luminosities the higher neutron yield. Recently detail studies of the sheath and pinch structure are carried out with an interferometry and Faraday rotation measuring