Plasma jet seven-array discharge at atmospheric helium gas

A low temperature plasma jet array device using seven single electrodes surrounded with insulated organic glass is designed to study the discharge properties of atmospheric plasma jet. The ambient gas is atmospheric Helium gas, whose flow rate is controlled from 0 L/min to 10 L/min. This discharge device is driven by a sub-microsecond repetitive high voltage pulsed power with the pulse width about 230 ns, the rising edge about 120 ns. Using a repetitive frequency rate about 500 Hz, the high speed photographs are taken and the current pulse width is about 110 ns. The average jet length was measured under the conditions of changing gas flow rate and pulse voltage amplitudes in the experiment, in order to acquire the interactions of every plasma jet discharge. It is found that the average plasma jet length increases with the increasing voltage amplitude when the voltage amplitude is less than 20 kV and that it increases slowly when the voltage amplitude is higher, up to 35 kV. It is also found that the average jet length reaches the maximum when the gas flowrate is at a regular value, that is, the average length decreases if the gas flowrate is over or under the regular range. Besides, it is also discovered that the central electrode discharge is affected extremely by the gas flowrate. The central jet length is almost invisible when the gas flowrate is very high or very low, while the central jet with a weak discharge is longer than the surrounding jets when the gas flow rate is 1 L/min. The main reasons are that the air blocks the jet developing and the central electrode jet channel is impeded by the surrounding jets. It is easier for the surrounding electrode to develop jets.