MITTON opening characteristics-dependence on grid bias voltage

The MIITON is a high voltage closing and opening switch. The switch is triggered into conduction by the application of a microwave pulse (3.05 GHz, 1 μs, ≈13 kW peak power) to a helix surrounding the grid region. The resultant electric field ionises the gas within the switch leading to closure. Uniform ionisation results in fast closure with anode fall times of 10 ns being measured. The MITTON is opened by applying a negative voltage pulse (≈1 μs, 1 kV) to the grid. The application of a negative voltage produces a positive ion sheath between the plasma and the grid, leading to an increase in the switch impedance. The current then falls, resulting in a progressive increase in impedance until the switch opens in a few hundred nanoseconds. Opening has been achieved at voltages up to 15 kV and currents of up to 15 amps