A low-current atmospheric pressure discharge generating atomic magnesium fluxes

In the present work, we studied the stable operation of an atmospheric pressure discharge with magnesium electrodes in air and argon flows. We employed a plasma generator consisting of a central cathode and a coaxial anode. At a direct discharge current up to 200mA, spontaneous transitions to a low-voltage (30-40V) burning regime were observed when the current was slightly raised by several milliamperes. This phenomenon is reflected in the optical spectrum by the appearance of corresponding lines of singly charged and exited magnesium atoms. It has been found that for a discharge fed by a pulsed power supply, at a unipolar pulse repetition rate of 100kHz, with the working gas of argon, the aerosol emission becomes stabilized. The aerosol consists of magnesium particles suspended in the argon flow that eventually mixes up with the surrounding air. Based on our estimates, we have made an assumption that the physical nature of the discharge maintenance lies in the ion-electron emission due to the interaction of argon ions with the magnesium cathode surface.