CF_4及其N_2混合物在普冷温区下绝缘机理分析（英文）

Breakdown mechanism of CF_4 and N_2 binary gas in refrigeration temperature range

普冷温区环境下气体绝缘机理依然不够明朗。本文在温度–153~25°C,气压50~2000 Pa的范围内对CF_4、N_2、20%CF_4/N_2以及50%CF_4/N_2混合气体进行了绝缘击穿试验。试验结果表明:气体临界击穿电压出现位置随着温度的降低向低气压偏移;N-2临界击穿电压随着温度的变化呈现明显的波动性,随着气体中CF_4含量的增高,混合气体临界击穿电压随着温度变化的波动性降低,纯CF_4气体临界击穿电压随着温度的降低呈单调下降趋势。这一现象与分子电负性强弱、附着效应、分子团以及二代电子崩的形成有关。

The mechanism of gas discharge in refrigeration temperature range is still not clear. N2, CF4, 20% CF4＋N2 and 50%CF4＋50%N2 binary gas mixtures were tested under the conditions of –153–25 ℃ and 50–2000 Pa. The experimental results show that the minimum of Paschen curves of all test samples shifts to low pressure, from 500 Pa to 200 Pa. The value of Paschen curve minimum of N2 shows remarkable fluctuation. This fluctuation is explained by molecule agglomeration and electronic mean energy. The fluctuation decreases with the increasing mixing ratio of CF4. What’s more, the value of Paschen curve minimum of CF4 decreases with temperature. This phenomenon is ascribed to attach-radiation and secondary process.