Design, Fabrication And Characteristics Of A Planar Solid-State High Voltage Single Shot Switch

Exploding foil initiator has obvious advantages on improving the safety and initiation speed of initiators. As the key component of capacitive discharge unit, high voltage triggered switches play the great role on the successful detonation of insensitive explosives. At present, several tapes of switches have been used to drive EFI systems including spark gap switches with three electrodes and triggered vacuum switches. But now these big volume switches not easily integrated are very expensive. This paper designs a novel switch called Planar Solid-State High Voltage Single Shot Switch. The structure has been designed to operate as a fast-turn-on, low-impedance device. The switch is a planar structure that allows for direct integration into the stripline geometries used in a conventional capacitive discharge unit. The switch fabrication process and the performance of Cu plasma were carried out in this paper. Finally we tested the switch discharging characterizations from several aspects. The main conclusions we gained are as follows:(1) Application of wet etching process and image-reversal process, Planar Solid-State High Voltage Single Shot Switch was successfully fabricated with Magnetron Sputtering. The optimum parameters of thin Cu film deposition and AZ5200 process were confirmed.(2) Electrical explosion curve tests showed that for our set of apparatus,1500V was the most matching voltage between the Cu films and experimental instruments. Explosion process of the trigger Cu film was observed by high speed camera which presented that the intensity of Cu plasma was very strong and spatial size was more than 3000μm. The Cu plasma emission spectrum line showed clear and its independence was better. The existing time of plasma exceeded 7000ns from development process of Cu emission spectra. Using Boltzmann plot method we calculated the electron temperatures of copper plasma and the electron densities of the plasma were calculated by Saha-Eggert equation. The results showed the electron temperatures of plasma rapidly rose to 7000K at the beginning and then slowly declined as time evolved. The change rule of densities of metal plasma was similar to the electron temperatures of plasma just discussed.(3) We made the designed planar switch used in the slapper detonating circuit. The voltage stress test showed the planar switch can withstand at least 3000V and met the need of McEFI system. With the rising of the main electrode distance, the delay time and jitter time of the switch, the inductance and resistance of the switch increased but the rising time and peak current of the switch decreased. When the main electrode shapes presented saw tooth, the delay time and jitter time of the switch, the loop peak current of the switch become relatively smaller. As the voltage of high capacitor in the trigger loop increase, the delay time and jitter time of the switch, the inductance and resistance of the switch, the rising time and peak current of the switch decreased, but peak current of the switch increased. Further more, before trigger electrode voltage achieved the most matching voltage of Cu films, variations of amplitude of the above-mentioned switch properties were relatively larger. Finally the mathematic models of high voltage switch designed by this paper and resistivity of EFI foil were established. With the Matlab language, Cu current curves had been simulated successfully and the results between actual measure and conclusion gained from analog line was basically the same.