Effect of Plasma Fluctuations on In-Flight Particle Parameters

摘要: The influence of arc root fluctuations in direct current (DC) plasma spraying on the physical state particle jet is investigated by correlating individual in-flight temperature and velocity measurements with instantaneous voltage difference between electrodes. In-flight diagnostics DPV-2000 sensing device involve two-color pyrometry time-of-flight technique for determination velocity. Synchronization torch are performed using an electronic circuit that generates a pulse when reaches some specific level; this pulse, which can be shifted arbitrary period time, used to trigger acquisition pyrometric signals. Contrary predictions obtained numerical modeling, time-dependent variations due power induced movement very large. Periodic mean velocity, up ΔT=600 °C Δv=200 m/s, recorded middle during cycle. To our knowledge, first time large effects (temperature velocity) experimentally demonstrated. Moreover, number detected particles observed throughout cycle; few parts existence quiet periods suggests injected at moments not heated sufficiently detected.