Velocity and texture of a plasma jet created in a plasma torch with fixed minimal arc length

Abstract

A new plasma jet (PJ-100) plasma spraying torch with a fixed minimal arc length was tested and the basic working parameters were measured and evaluated. The velocity of the plasma exiting both the cylindrical and the conical anode nozzles was assessed by measuring the thrust generated by the plasma jet and by photographing the translation of plasma clouds (parts with different brightnesses) in the last third of the length of the plasma plume. The basic characteristics of the argon/hydrogen plasma jets (enthalpy, mean temperature, mean plasma velocity and effective exhaust thrust velocity) were determined for different working regimes, for both the cylindrical and the conical nozzles. The thermal efficiency of the new plasma torch is between 70% and 74% for the plasma generation power up to 90 kW. The plasma plume generated in the cylindrical nozzle has a homogeneous radial temperature (and velocity) distribution with a full laminar flow.

On the Gas Heating Mechanism for the Fast Anode Arc Reattachment in a Non-transferred Arc Plasma Torch Operating with Nitrogen Gas in the Restrike Mode

“…Unlike non-transferred arcs with fixed minimal lengths [3], the anode attachment location in a non-transferred arc is usually in motion, thus inducing arc voltage fluctuations. Three distinctive modes have been reported for the arc voltage fluctuations: the steady mode, rather detrimental for the anode life time because the anodic attached spot remains almost fixed in position; the takeover mode, obtained mainly with mono-atomic gases in which the anode attached spot presents a small amplitude oscillating motion; and the restrike mode, corresponding to diatomic gases or their mixtures, in which the spot expands along the anode moving away from the cathode (stretching the arc) until a new arc appears closer to the cathode and the original arc decays, giving place to an expanding movement of the new arc [4].…”

Hydroxyapatite coatings prepared by a high power laminar plasma jet

“…Vilotijevic et al (2009) documented that the plasma jet generated with this installation has considerably better characteristics of flow laminarity, temperature homogeneity, and higher plume velocity than that generated by the conventional PG. Fig.…”

“…The first difference between the plasma jet which is generated by PJ-100 installation and the one derived by the conventional PG can be seen in terms of plasma velocity. The PJ-100 plasma velocities, measured at its very end in the zone of 60-70 mm from anode nozzle exit, were 1500-1800 m/s (Vilotijevic et al, 2009). At the same distance from the anode nozzle exit, the plasma jet velocities of the conven- tional PG were determined to be about 200-400 m/s for the power range of 11-24 kW, respectively, as reported by Dyshlovenko et al (2004).…”

Multi-Electrode Plasma Torches: Motivation for Development and Current State-of-the-Art

“…The long arc length stabilizes the arc by limiting the axial movement thus producing a constant power demand. Similar developments are currently in use with the so-called PJ 100 torch from Plasma Jet Co. [12]. These plasma torches not only produce a more stable jet but make it also easier to adjust the total enthalpy of the plasma gas (T (r))v axial (r)h(T (r))2 r dr r=0 r=R W eff (1) by allowing to adjust the voltage as well as the jet radius by using different gas mixtures.…”