So far, several MFCs were simply connected in series or in parallel to overcome the low voltage or power issue. However, although a serially stacked MFCs unit could provide a higher voltage, it has often been proven to be difficult and ineffective due to voltage reversal (reverse polarity owing to fuel shortage) of individual MFC units, leading to a significant overall voltage decay2,5,6,7. Recently, significant efforts have been made to control and suppress the voltage reversal occurrence by connecting individual MFC units with a maximum power point tracking (MPPT) system to charge a stacked polarized capacitor8,9. However, this technical approach could increase stacked voltages only within the range of 2 to 3 V8,9.
The gas discharge in a gas peaking switch was experimentally studiedand numerically simulated. For simulation, the discharge was divided intotwo phases, gas breakdown and voltage collapse. The criterion for anelectron avalanche to transit to streamer was considered as the criterionof gas breakdown. The spark channel theory developed by Rompe-Weizel wasused to calculate the spark resistance. It was found that the prepulseconsiderably lowers the voltage pulse applied to the gap. Even for a giveninput pulse, the voltage pulse applied to a peaking gap is different fordifferent gap distance due to existence of a different prepulse. In thiscase, the breakdown voltage of a gas peaking gap depends on gas pressureand gap distance, individually. For nitrogen pressure varying from 3 MPato 10 MPa and gap distance from 0.6 mm to 1.2 mm, the peak electric fieldhigher than 2 MV/cm was achieved when breakdown. The output 10% to 90%rise time, tr, varies from 145 ps to 192 ps.As gas pressure increases, tr decreases,which can be explained by the fact that the breakdown field increases withthe increase of gas pressure. It was found in experiment that the jitterin tr could be attributed to the jitter inbreakdown field. Instead of getting longer, the averaged experimentaltr gets shorter as gap distance increasesfrom 0.6 mm to 1.2 mm, which differs from the results of calculation andindicates there may exist something, other than electric field, that isalso related to tr. The reason for thisdifference may lies in the inverse coefficient of spark resistance varyingwith gap distance. On the whole, the results from the calculations agreewith the experimental ones.
High Voltage Engineering Fundamentals Kuffel Pdfl
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