Propagation of plasma bullets in helium within a dielectric capillary?influence of the interaction with surfaces
This paper reports an experimental study on the propagation of an ionization wave inside a thin capillary, called ?plasma bullet?. A low-frequency sinusoidal voltage is applied and several bullets are emitted during each cycle. The delay between two successive discharges is short enough so the propagation of one bullet is influenced by the charges deposited on surfaces by the previous one. It was shown that the propagation length increases during the cycle. An interesting result is that a discontinuity during the propagation of a bullet has been clearly pointed out. When it crosses the discontinuity, the bullet has been shown to increase its light emission and its propagation velocity. It was explained by a transition between regions of different potential, due to charges deposited by the previous bullets.
Abstract Thanks to their high hydrogen permeability, vanadium based alloys can be a valuable and sustainable alternative to palladium alloys, commonly employed in commercial membranes for hydrogen purification/separation. In this work, the unprecedented deposition of micrometric vanadium-based multilayers and their investigation as hydrogen selective membranes have been reported. In particular, this work describes the use of High Power Impulse Magnetron Sputtering, a technique easily scalable also for complex geometries, for the deposition of dense and crystalline Pd/V93Pd7/Pd multilayers with total thickness