Helical coil CW RF excitation of ion laser discharges

An rf discharge is produced by a helical coil with its axis parallel to the laser tube resonator axis. The energy is coupled into the discharge by the circulating currents induced in the relatively low resistivity plasma by the rf magnetic field. These currents are in a plane perpendicular to the rf magnetic field. The discharge is initiated by the electric field along the length of the coil.