Cryogenic dielectrics are a crucial component for applied superconducting systems such as high-temperature superconductor (HTS) cables. Here two types of polymer nanocomposites were investigated as dielectrics for cryogenic applications. Both polyimide (PI) and polyamide (PA) nanocomposites showed exceptional performance as dielectrics, with PI as the stronger material. Significant dielectric strength improvement was observed for samples tested in the cryogenic environment when compared to those tested at the room temperature. The PI exhibited a high dielectric strength of 347 ± 67 kV/mm at 92 K, while its nanocomposites were in the range of 261-280 kV/mm. The performance change of these dielectrics was influenced by a number of factors including the density of free charge carriers, localized heat generation and material degradation, thermal contraction of polymers, and polymer-nanoparticle interfacial changes at cryogenic temperatures. The findings from this research can help advance the understanding of breakdown failures in cryogenic dielectrics.

中文翻译：

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聚酰亚胺 (PI) 和聚酰胺 (PA) 纳米复合材料的温度相关介电性能

低温电介质是高温超导 (HTS) 电缆等应用超导系统的重要组成部分。这里研究了两种类型的聚合物纳米复合材料作为低温应用的电介质。聚酰亚胺 (PI) 和聚酰胺 (PA) 纳米复合材料作为电介质都表现出卓越的性能，其中 PI 作为更强的材料。与在室温下测试的样品相比，在低温环境中测试的样品的介电强度显着提高。PI 在 92 K 下表现出 347 ± 67 kV/mm 的高介电强度，而其纳米复合材料在 261-280 kV/mm 的范围内。这些电介质的性能变化受到许多因素的影响，包括自由电荷载流子的密度、局部发热和材料降解，聚合物的热收缩，以及低温下聚合物-纳米颗粒界面的变化。这项研究的结果有助于加深对低温电介质击穿故障的理解。