Time delay of a field-breakdown triggered vacuum switch with flat electrodes

Triggered vacuum switch (TVS) is one of the important switch apparatuses in the field of pulsed power system. The field-breakdown will bring long lifetime of TVS under rated working conditions. However, the load of trigger will be heavy, leading to the large time delay and jitter time. In this paper, a field-breakdown TVS sample with flat electrodes was fabricated and its time delay was tested. Initial plasmas play an important role in the turning-on process of TVS, so the time delay from the control signal to the switching-on of TVS is discussed in the trigger system time, the motion time and the collapse time, where the motion time and the collapse time are the needed time for the generation and development of the initial plasmas. Test results show that, under positive working mode, the trigger system time is about 34–36 μs with positive trigger pulse, while 39–41μs with negative trigger pulse, which prove that the polarities of trigger pulse have nothing to do with the trigger system time almost, and the long trigger system time is mainly owing to the limited performances of trigger pulse transformer. The motion time is about 50 ns and almost stable, due to the definite trigger gap. The collapse time is about 100–300 ns, which is decreased with the rise up of main gap voltage, exponentially. In negative working mode, both of the motion time and collapse time are about 10 μs, due to the ions of initial plasmas becoming the main moving particles in the main gap, no longer the electrons as positive working mode.