Plasma focus modification for material surface treatment

Abstract

The Plasma Focus Device has been studed since 1960. It is an excellent device for studying plasma dynamics and thermodynamics as well as being a rich source for a variety of plasma phenomena including soft x-ray production and plasma nuclear fusion. Plasma focus is a device that generates and accelerates plasma along Z-direction with Lorentz force. It produces a high-density (n>10[superscript 19] cm[superscript -3]) and high temperature plasma with a short life time of less than 100 ns during "focussing". This "focussing" process can be an intense source of neutron, X-ray radiation, ions beam, electron beam, and plasma jet. In this research, a 3 kJ plasma focus device was built and modified with an attempt to produce a consistent ion beam and plasma jet for surface modification and coating of materials. The properties of the plasma from the plasma focus were studied. Several diagnostic tools such as high voltage probe, Rogowski coil, magnetic probe, electric probe were used for characterisation. Results from these measurements are compared with a numerical model. It was found that the discharge current of the plasma is 136.77 kA and the speed of the plasma sheath can reach up to 6 cm/micro-s under 0.5 mbar of pressure. Average speed of the plasma jet was also estimated to be 0.6 cm/micro-s. Based on these results many reported publications, several areas of modification method are explored. Thorough experiments were carried out to study the effects of Argon and Nitrogen plasma on materials such as glass, Titanium, Aluminum and steel. The major contribution to surface modification process is possibly from a heating effect as well as a bombardment of ions or plasma jet.