Due to the high conductivity of plasma, a thyratron is capable of switching higher currents than vacuum tubes which are limited by space charge. A vacuum tube has the advantage that conductivity may be modulated at any time whereas a thyratron becomes filled with plasma and continues to conduct as long as a voltage exists between the anode and cathode. A pseudospark switch operates in a similar regime of the Paschen curve as a thyratron and is sometimes called a cold cathode thyratron.