The behaviors of creeping streamer progressed in the narrow gap with the range of 0.1 mm to 0.2 mm between the pressboard mounted a BSE （back side electrode） and the acrylic resin plate were carried out in PFAE （pa...The behaviors of creeping streamer progressed in the narrow gap with the range of 0.1 mm to 0.2 mm between the pressboard mounted a BSE （back side electrode） and the acrylic resin plate were carried out in PFAE （palm fatty acid ester） oil under variable impulse voltage up to -4-140 kVpeak with ＋1.2/50 μs and ±1.2/1,000μs waveforms. The growth of positive and negative streamers depends on the gap space between two solid dielectrics. And the distinctive polarities of impulse voltage affect in the streamer length and flashover voltage between needle and counter electrodes as well. By decreasing the gap space, the flashover voltage largely increased while the mean velocity of positive streamer significantly decreased under the both polarities of impulse voltage. These results have been compared to commercial mineral oil （transformer oil： JIS-C2320）. It is shown that the behaviors of creeping discharge in both oils elegantly reveal the distinctive phenomena.展开更多
The E ～ j relation of an HTSC slab is solved strictly within the Bean’s model in two different situations where the system does and does not reach equilibrium state under the magnetic relaxation respectively, with b...The E ～ j relation of an HTSC slab is solved strictly within the Bean’s model in two different situations where the system does and does not reach equilibrium state under the magnetic relaxation respectively, with both forward and backward hopping taken into consideration (the backward hopping means the hopping from the barriers with low energy to high ones). Our results suggest and rigorously prove that the In E ～ In j curves show only positive curvature on the side of slab where the directions of current-created field and the applied field are the same, while they show both positive and negative curvatures at a certain field range on the other side where the directions are opposite. The relationship of the positive and negative curvatures with the critical current, applied field and temperature is also discussed.展开更多
文摘The behaviors of creeping streamer progressed in the narrow gap with the range of 0.1 mm to 0.2 mm between the pressboard mounted a BSE （back side electrode） and the acrylic resin plate were carried out in PFAE （palm fatty acid ester） oil under variable impulse voltage up to -4-140 kVpeak with ＋1.2/50 μs and ±1.2/1,000μs waveforms. The growth of positive and negative streamers depends on the gap space between two solid dielectrics. And the distinctive polarities of impulse voltage affect in the streamer length and flashover voltage between needle and counter electrodes as well. By decreasing the gap space, the flashover voltage largely increased while the mean velocity of positive streamer significantly decreased under the both polarities of impulse voltage. These results have been compared to commercial mineral oil （transformer oil： JIS-C2320）. It is shown that the behaviors of creeping discharge in both oils elegantly reveal the distinctive phenomena.
基金We thank Prof. Yao Xixian at Nanjing University for many helpful discussions and great help. This work was supported by National Laboratory for Superconductivity and the Key Project of Chinese Academy of Sciences.
文摘The E ～ j relation of an HTSC slab is solved strictly within the Bean’s model in two different situations where the system does and does not reach equilibrium state under the magnetic relaxation respectively, with both forward and backward hopping taken into consideration (the backward hopping means the hopping from the barriers with low energy to high ones). Our results suggest and rigorously prove that the In E ～ In j curves show only positive curvature on the side of slab where the directions of current-created field and the applied field are the same, while they show both positive and negative curvatures at a certain field range on the other side where the directions are opposite. The relationship of the positive and negative curvatures with the critical current, applied field and temperature is also discussed.
