Vacuum are plasma jets and their applications

Abstract

Summary form only given. The vacuum arc is a high current, low voltage electrical discharge in which a conducting medium is supplied in the form of vaporized electrode material. The plasma production is localized at one or several minute locations on the cathode (dependent on the arc current), known as cathode spots. The vacuum arc plasma originates from the cathode spots is a supersonic highly ionized plasma jet. Due to superior properties vacuum arc plasma jets have various applications. Historically high current interrupters were the first significant commercial application of the vacuum arc. The metal plasma jet produced by the vacuum arc is an attractive source of high-energy metal ion flux for the deposition of thin metallic films and multi-layers. A vacuum arc is excellent source of multiply charged metal ions and is used to create intense ion beams. Recently several other applications of the vacuum arc were proposed, such as plasma immersion ion implantation and plasma propulsion. Vacuum arc phenomena occur in unipolar arcs during current rise in Tokamaks and in exploding wires. The vacuum arc jet consists of ions, electrons, neutral vapor, and macroparticles (MP). MPs usually limit vacuum arc applications and considered as the major disadvantage. The MP's are molten droplets or solid particles (0.1-100 /spl mu/m in size), which are generated in the cathode spot region by action of the plasma pressure. In this work state-of-art of the vacuum arc plasma jet simulation will be reviewed. The principles of aforementioned applications will be also discussed. Several mechanisms of macroparticle elimination based on the fact that macroparticles are charged in the plasma will be considered. The vacuum arc plasma jet flow will be analyzed using the 2D hydrodynamic free plasma jet boundary expansion model. Several effects will be considered in this contest, such as multiply charged ions transport and separation, plasma jet behavior in a magnetic field and effects associated with electrode geometry. The diffuse vacuum arc in an axial magnetic field and V-shape arc voltage characteristics in a magnetic field will be discussed.