This paper investigates the dielectric breakdown properties of humid air, taking into account ion kinetics. Initially, an overall kinetic scheme that includes all the main reactions likely to happen in humid air is established for the first time. Then, the calculation method of dielectric properties is improved, based on more comprehensive avalanche model considering both spatial growth and temporal processes. Better consistency between present results and experimental values confirms the validity of the improved method and kinetic schemes. Finally, the effective ionization Townsend coefficients αeff in humid air at different humidity and gas pressures are calculated and analyzed considering ion kinetics. Reduced critical electric field strength (E/N)cr can be determined when αeff  =  0. The results show that (E/N)cr in humid air increases sharply in the beginning and then tends to be constant with the humidity rises. Besides, the mechanism of humidity’s effect on dielectric breakdown properties is well explained: at relatively low E/N, αeff decreases with the increase of humidity mainly due to more frequent three-body conversions, while at higher E/N, the main reason is the increased number of attachment reactions.

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We report electron transport studies of a thin InAs-Al hybrid semiconductor-superconductor nanowire device using a four-terminal design. Compared to previous works, thinner InAs nanowire (diameter less than 40 nm) is expected to reach fewer sub-band regime. The four-terminal device design excludes electrode contact resistance, an unknown value which has inevitably affected previously reported device conductance. Using tunneling spectroscopy, we find large zero-bias peaks (ZBPs) in differential conductance on the order of 2e 2 /h. Investigating the ZBP evolution by sweeping various gate voltages and magnetic field, we find a transition between a zero-bias peak and a zero-bias dip while the zero-bias conductance sticks close to 2e 2 /h. We discuss a topologically trivial interpretation involving disorder, smooth potential variation and quasi-Majorana zero modes.

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