Corona discharge with a discharge current of a few hundred microamperes can blow out a small candle flame within about 1 cm of a discharge point. A pinwheel, with radial metal spokes and pointed tips bent to point along the circumference of a circle, can be made to rotate if energized by a corona discharge; the rotation is due to differential electric attraction between the metal spokes and the space charge shield region that surrounds the tips. Corona discharge A corona discharge is an electrical discharge brought on by the ionization of a fluid such as air surrounding a conductor that is
Townsend discharge discharge sets the upper limit to the blocking voltage a glow discharge gas-filled tube can withstand. This limit is the Townsend discharge breakdown voltage, also called ignition voltage of the tube. The occurrence of Townsend discharge, leading to glow discharge breakdown shapes the current-voltage characteristic of a gas discharge tube such as a neon lamp in a way such that it has a negative differential resistance region of the S-type. The negative resistance can be used to generate electrical oscillations and waveforms, as in the relaxation oscillator whose schematic is shown in the picture on the right. The sawtooth shaped