A pseudo-spark switch triggered by a pulsed low-current gas discharge has been developed. It switches medium voltages and currents of typically less than 20 kV and 10 kA, respectively. The switch works at high repetition rates of up to 100 kHz and fast rates of current rise of up to 5*10¹¹ A s^-1. At positive charging voltage, the jitter may be much smaller than 1 ns. This pseudo-spark switch has been successfully tested by running a discharge-heated longitudinal copper vapour laser and a transverse Blumlein N₂ laser, replacing a hydrogen thyratron and a high-pressure spark gap switch, respectively.