As a method for investigating the minimum energy to produce a pinch plasma focus (PF) discharge, an ultra-miniature device for pinch discharges has been designed, constructed and characterized (nanofocus (NF): 5 nF, 5-10 kV, 5-10 kA, 60-250 mJ, 16 ns time to peak current). Submillimetric anode radii (0.8 and 0.21 mm) covered by coaxial insulators were used for experiments in hydrogen. Evidence of pinch was observed in electrical signals in discharges operating at 3 mbar and ∼100 mJ. A single-frame image converter camera (4 ns exposure) was used to obtain plasma images in the visible range. The dynamics observed from the photographs is consistent with (a) the formation of a plasma sheath close to the insulator surface, (b) the plasma covering the anode, (c) radial compression over the anode; (d) finally the plasma is detached from the anode in the axial direction. The total time from stages (a) to (d) was observed in ∼30 ns. This ultra-miniature device has a value for the 'plasma energy density parameter' and for the 'drive parameter' of the same order or greater than PF devices operating at energies several orders of magnitude higher.

An experimental study on hard x-ray production in a small plasma focus device operating in a few hundreds of Joule range is presented. A threshold in the voltage drop on the pinch was observed for x-ray emission. A comparison with Dreicer theory for electrons runaway in plasmas yields significant agreement. The study was performed at a constant pressure (1.8 mbar) of deuterium with three different anode lengths.

At present the Plasma Physics and Plasma Technology Group of the Comisión Chilena de Energía Nuclear (CCHEN) has the experimental facilities in order to study fast dense transient discharges in a wide range of energy and current, namely: I) energy from hundred of kilojoules to tens of joules, II) current from megaamperes to tens of kiloamperes. Also several diagnostics have been implemented. An overview of the work being carried out on dense pinch plasma focus discharges at the Comisión Chilena de Energía Nuclear is presented. The plasma energy density and scaling laws for the neutron yield are discussed. Possible applications of the radiation emitted are also discussed.