Dynamic Electric Potential Redistribution And Its Influence On The Development Of A Dielectric Barrier Plasma Jet

We investigate the initiation and development of a streamer-like plasma jet generated in a single-electrode dielectric barrier configuration at atmospheric pressure. The influence of dielectric boundary conditions on discharge propagation dynamics, morphology and current distribution was studied using spatially and temporally resolved emission spectroscopy and wide-bandwidth current measurements. A Phantom high-frame-rate camera system was used to visualize discharge inception as a function of pulse repetition frequency, which was varied between 1 and 20 kHz. At discharge inception, with the copper ring anode located 20mm behind the capillary tip, the discharge propagated along the 2mm diameter inner wall of the glass capillary regardless of pulse repetition frequency. The steady-state morphology remained annular below 6 kHz, but gradually transitioned to an axial morphology with the expansion of a dark wall sheath towards the anode as the pulse repetition frequency was increased to 10 kHz. In the axial mode, the ionization front steadily decelerated with a corresponding decrease in peak emission intensity, while emission from the residual plasma channel increased. This indicated a dynamic redistribution of electric potential from the ionization front into the residual plasma channel that was attributed to charge accumulation on the dielectric surface between discharge pulses.
Pub in PLASMA SOURCES SCIENCE AND TECHNOLOGY, v21, p1-11, 2012. The original document contains color images.