Results are presented for physical experiments that illustrate the possibilities and efficiency of visualization for studying the effect of operating conditions (backward-facing stepped forming nozzle, exit diameter of anode, mass flow, and composition of working gas) on plasma flows at low Reynolds numbers for advanced coating and powder processing. In particular, the shadow method, based on a...

Arc ablation holds the promise of fast, low-cost metal removal at faster rates than laser, plasma and electron-beam methods and without the tooling and fixturing forces of conventional machining. Preliminary results show surface finishes in the tens of microns range at high material removal rates (MRRs) by adaptive control of arc voltage: up to 97 mm3/sec at 4 kW. These results far exceed the c...

Defects during Plasma Transfer Arc (PTA) beam fusion additive manufacturing (AM) processing of Ti-6Al-4V, including lack of fusion, porosity variations, and solidification cracking, have been monitored using near infrared (1.62 μm) imagery at 300 Hz, 300 μm spatial resolution and melt pool sizes of greater than 12μ. The temperature evolution exhibits a periodic temperature modulation of more th...

In this paper, the experimental design of using the Taguchi method is employed to optimize the processing parameters in the plasma arc surface hardening process. The processing parameters evaluated are arc current, scanning velocity and carbon content of steel. In addition, other significant effects such as the relation between processing parameters are also investigated. An orthogonal array, s...

Various techniques including plasma-arc, laser ablation, and chemical vapor-phase synthesis have been employed to Ž . produce bulk amounts of non-carbon such as boron nitride, BN nanotubes with some success, but in general the yields are low. We describe a new high-yield plasma-arc method that easily and reliably produces macroscopic amounts of pure BN nanotubes. Interestingly, the method produ...

In an earlier paper [Kosch et al., 1998], simultaneous all-sky TV imager and Scandinavian Twin Auroral Radar Experiment (STARE) observations of an ionospheric plasma vortex located poleward of an auroral arc were presented. The vortex is associated with a sudden brightening of the arc and corresponds to an ionospheric region of diverging horizontal electric fields, which is equivalent to a down...

Plasma acid is an acidic solution simply produced from water and a carrier gas in an electrical discharge. These produced solutions are of high value for biological decontamination and industrial pollutant abatement applications. While several electrical discharges have been shown to produce plasma acid, the subject of this study is the gliding arc plasmatron, a rotating gliding arc discharge. ...

Keyhole plasma arc welding is a unique arc welding process for deep penetration. To ensure the quality of the welds, the presence of the keyhole is critical. Understanding of the keyhole will certainly benefit the improvement of the process and weld quality. Currently, the size of the keyhole is assumed to be correlative with the robustness of the keyhole process in maintaining the keyhole. To ...

Nanocrystals in the lower-nanometer-size range are attracting growing interest due to their unique properties. A simple and versatile atmospheric direct current mini-arc plasma source has been developed to produce nanoparticles as small as a few nanometers. The nanoparticles are formed by direct vaporization of solid precursors followed by a rapid quenching. Both semiconductor tin oxide and met...

The spatio-temporal appearance and distribution of proteins forming the intercalated disc were investigated in adult rat cardiomyocytes (ARC). The 'redifferentiation model' of ARC involves extensive remodelling of the plasma membrane and of the myofibrillar apparatus. It represents a valuable system to elucidate the formation of cell-cell contact between cardiomyocytes and to assess the mechani...