Plasma Focus Installation Research Articles

The structure and current-voltage characteristics of copper-tungsten electric contacts prepared using a Plasma Focus installation

The structure and current-voltage characteristics (CVCs) of copper-tungsten electric contacts deposited using a Plasma Focus facility are studied. It is shown that the reduced contact resistance is ∼0.4 × 10−6 Ω cm2 at 300 K and ∼0.4 × 10−7 Ω cm2 at 80 K, which meets the highest requirements for ohmic contacts in electrical installations and semiconductor electronics. The formation of microcracks on the surface of tungsten exposed to high-speed plasma streams has no significant impact on the contact resistance. Under the effect of high pressure, a melt of copper penetrates deep into tungsten along the cracks, solidifies, and thereby forms zones of high conductivity. The soldering of electric contacts with tin solder leads to CVC deviation from linearity at 80 K. A probable cause of this is the formation of SnO2-copper Schottky barriers on the surface of Cu-W contacts.

The effect of pulse high-density plasma on superconducting properties of Bi-2223 multilayered tape

The effect of pulse high-power nonlinear shock waves generated at the Plasma Focus installation, which was created according to the nuclear fusion program, on some characteristics of multilayered high-temperature superconducting (HTSC) Bi-2223 tape is demonstrated. The tape is produced using the technique of HTSC powder rolling in a silver coating. A more than a twofold increase in the critical current in zero magnetic fields and external magnetic fields from 0.5 to 6 T at a temperature of 77 K is shown to take place under the action of shock waves at room temperature. The volt-ampere characteristics (VACs) of HTSC tape samples exposed to the effect of shock waves are found to drastically differ from the characteristics of the initial tapes. The shock waves suppress the “gear”-type VAC character of unprocessed plasma samples, their jump amplitudes increasing with an increase in the applied magnetic field intensity.

Application of high velocity streams of dense plasma for the creating of high adhesive compounds of chemically noninteracting metals

The work presents the experimental results of investigation of the possibility of the creating of high adhesive compound of chemically noninteracting metals by means of pulse streams of high temperature dense plasma. The 4 kJ plasma focus installation was used as a source of pulse streams of plasma. In the experiment assemblies of Cu–W and Pb–Fe samples were used. The deep penetration of atoms Cu and Pb accordingly in W and Fe was found. The mechanisms of the penetration of chemically neutral atoms into a material of the target can be connected with the following processes: the energy transfer from plasma pulse to implanting atoms, the origin and distribution of shock waves in the material of a target, and also the Rayleigh-Taylor instability of the border of two combining materials.

Changes of internal properties of vanadium and structure of its surface under the effect of pulsed high-temperature deuterium plasma

The work presents experimental research of the influence of a pulse of high-temperature dense plasma on materials, which as are supposed, will be used in future thermonuclear power stations. The experiments were made on 4 kJ Plasma Focus installation. Such type of installations is capable to form pulse of axial plasma flows moving with velocity approximately 108 cm/s and plasma density is about 1018 cm−3. Pure vanadium was chosen in our researches, because it can be used as a basic element at the creation of low-activated alloys. We found that due to a pulse irradiation of vanadium by deuterium plasma, shock waves arises, which result in super-deep penetration of deuterium into a volume of the studied sample. This process is accompanied with the change of vanadium structure, the occurrence of pores in it, and changes of its mechanical properties. The break-away of vanadium particles from the backside surface of the sample and forming of craters were also observed.

Investigation of photoabsorption effects of Li-like satellites in inhomogeneous hot dense pinching plasmas

Single-shot space-resolved X-ray spectra from He-like and Li-like argon ions of the plasma focus installation DPF-78 were analysed by means of spectra simulations. Spectra from different hot spots, even from single discharges, showed up with considerable intensity variations of the Li-like 1s2l2l'-1s22l'' satellites which cannot be ascribed by temperature variations. It is shown that photoabsorption of the Li-like satellites in outer cold plasma clouds which surround the hot spots can be responsible for the observed effect.

Control and command system for pulsed, high power fusion experiments

Abstract A Control and Command System (SECAM-4/5A) designed for the Plasma Focus Installation IPF-4/5A (1 MA plasma current and 40 kJ energy stored at 20 kV charging voltage) is presented.