The characterization of plasma bursts produced after the pinch phase in a focus hundreds joules, using pulsed optical refractive techniques, is presented. A Nd-YAG laser at 532 nm and 8 ns FWHM pulse duration was used to obtain Schlieren images different times dynamics. energy, interaction time with target, power flux burst were assessed, providing useful information for application devices studying effects fusion-relevant pulses on material targets. In particular, it found that damage...

The basic engineering criteria for conceptual design of plasma focus devices is derived from a thermonuclear model, and applied successfully to the operation small neutron pulsors. theory able explain variation yield with gas pressure in deuterium-filled chambers, current evolution, electrode geometrical parameters. performance prototype designed optimize flux/fluence ratio presented, contrasting experimental outcomes model. A set effective parameters deduced, which ensure band confidence 20%.

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

As a first step in the design of repetitive pulsed neutron generator, very small plasma-focus device has been designed and constructed. The system operates at low energy (160 nF capacitor bank, 65 nH, 20–40 kV, ∼32–128 J). electrode was assisted by computer model Mather plasma focus. A single-frame image converter camera (5 ns exposure) used to obtain images visible range. umbrellalike current sheath running over end coaxial electrodes pinch after radial collapse can be clearly observed...

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

In this paper, a fast running computer model of plasma focus device is presented. The based on the snowplow constructed with effective parameters validated against experimental results. A pinch included to calculate temporal evolution focal variables. resulting neutron yield predictions are compared available data at different pressures, electrode length, and capacitor voltages from measurements, finding good agreements. ultimately calculates production given geometric filling deuterium pressure.

Applications of a small-chamber Plasma Focus used as portable radiation generator is presented. The device was designed to maximize the fluence. mean neutron yield 3 x 10(8) neutrons 2.45 MeV per shot, corresponding 10(6) neutrons/cm² fluence on external surface chamber. A technique detect presence water in neighborhood compact measuring system composed by two detectors operated simultaneously every shot. first detector register PF each shot; whereas other one for detecting scattered...

A discussion of the initial phase in plasma focus devices is given, light available experimental and theoretical knowledge on this subject. The influence also discussed.

A technique for the determination of inductance evolution in coaxial discharges based on measurements voltage between electrodes and discharge current time derivative is presented discussed. The applied to performed a 5.7 kJ plasma focus device operating with deuterium filling 1–6 mbar range (which neutron yield range) obtained results are good agreement expected sheet within system.

Measurements with magnetic probes performed in the initial phase of a plasma focus device (30 kV, ) pressure range 0.5 - 5 mbar deuterium are presented, and an interpretation obtained signals is given, which includes procedure for disentangling effect variations discharge current from signals. Thick sheaths, essentially filling all space between electrodes, shown to form at pressures, travelling radially outwards constant speeds 2.5 3.4 . Experimental confirmation theoretical prediction...

The measurement of the voltage between electrodes and discharge current time derivative in Plasma Focus devices can be used to obtain important information on neutron-producing pinch stage mentioned devices. analysis a 60-shots experimental run 5.7 kJ Mather-type device results correlations suggesting that neutron yield depends mostly average energy per particle delivered plasma during stage.

A simple model describing the lift-off of current sheet in initial stage plasma focus (PF) discharges is presented. The results are supported by measurements performed on a low energy PF device and also with other experimental found literature. ideas used have sufficient general validity so that they can be applied to essentially all existing devices.

The pinching efficiency of a plasma focus operating with an open cathode was studied by reconstructing the temporal evolution inductance plasma-electrodes system. It found that performance as neuron generator is substantially reduced compared same device configured surrounding cage-like cathode. In particular, no occurred in 30 shots performed at 1, 2 and 3?mbar without outer electrode.

An experimental study on plasma focus fusion mechanisms is presented in this paper. Simple diagnostic techniques such as current derivative, voltage, and time-integrated neutron detectors are used. This paper allows us to obtain information present a medium energy [Auto Confined Plasma (PACO), 2 kJ, 31 kV, T=2.9 μs]. The sheet (CS) inductance calculated through the anode voltage derivative signals, for some 80 shots performed within pressure range 0.8-2.1 mbar of deuterium. It concluded that...

The time-varying inductance of the plasma-electrode system in large plasma focus (PF) device PF1000 is experimentally determined from voltage and current-time derivative signals. signals were acquired several shots performed at same conditions (2.4 mbar D <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , 24 kV). Using these results, temporal evolution drop on pinch column also assessed. maximum values drops exceed 100 kV all shots.

A systematic study of TiN coatings produced with a low-energy pulsed plasma arc (500 peak current, 35 ms half-amplitude-full-width duration) is presented. The background pressure was varied in the range 0.6 - 10 mbar. Several diagnostic techniques were employed to coatings: Scotch tape test, weighting, scanning electron microscopy (SEM), x-ray diffraction (XRD), photoelectron spectroscopy (XPS), and Vickers microhardness. results show that two different microstructures can be obtained by...

A numerical model for the equivalent electrical circuit of a capacitive discharge that includes effects finite closure time switches and transit in transmission line is presented. An approximate analytical method to predict oscillations can be excited developed. The yields complex behavior over magnitudes currents voltages pulsed circuits simple configurations studies. Some predicted by calculations admit physical interpretations limiting cases (and are then predictable without need...

The effect of finite closure time switches in fast transient electrical circuits is presented. A simple theoretical model to predict the influence switching action developed, yielding a good description measured behavior.

An experimental study on the fluctuations in instants of time and amplitudes peaks voltage, current derivative, X-rays, neutron signals during a 150-shot series 2 kJ Plasma Focus device is presented. The results show reasonable correlation between voltage peak that X-ray emission, agreement with picture formation an electron beam accelerated by this voltage. However, differences X-rays maximum emission are difficult to interpret terms common origin.

The perturbations on magnetic probe signals, due to current redistribution in current-carrying plasmas, caused by the encasing body of are discussed. Calculations presented evaluating these for plane distributions, and relevance this effect is analysed.

The possibility of producing radiative collapses in pinches is studied using a 1/2D numerical model with pure bremsstrahlung as the source radiation, including anomalous resistivities and axial mass losses. results show existence both lower an upper limit value pinch current to produce collapses. It also shown that minimum initial radius (which depends on particle density) required order obtain inclusion losses makes production collapse more difficult, because it enhances resistivity heating.

First Page

The evolution of the plasma obtained from magnetic probes and other electrical measurements in a coaxial gun with Ti central electrode (cathode) used for coating studies mbar N2 atmosphere is given. results indicate that currently snowplough models adequately describe cinematic current sheet only if an additional mass to gas between electrodes included sheet. need include extra taken as evidence relevant erosion electrode, accordance production substantial coatings similar devices. Evidence...