中文摘要：

为了解超临界状态下二氧化碳的直流放电特性，采用间距为200μm的点板形电极（其点电极尖端的曲率半径为35μm），实验研究了二氧化碳从气态、液态到超临界状态下的直流放电行为。研究表明二氧化碳在直流电场下的击穿特性随着温度和压力的变化而变化，在不同形态下击穿电压的增长速率是不一样的。由于液态中存在气泡触发效应，所以它的击穿过程与气体状态比较类似，而在超临界状态中击穿电压的增长速率较低，可能与超临界状态下的奇异特性相关。

英文摘要：

The discharge not only in the gas but also in the liquid and supercritical carbon dioxide I was researched in order to study the characteristics of direct current discharge in supercritical carbon dioxide. The gap length of the point to plane electrodes was 200μm, and the curvature radius of the point was 35μm. The breakdown characteristics of carbon dioxide in the direct field corresponded to the changing of temperature and pressure. The increasing rates of the breakdown voltage were different in different phases. Breakdown trait in liquid was similar to that of gas because of bubble triggering effect in liquid. The low increasing rate of breakdown voltage in supercritical carbon dioxide might be related to the unique characteristics of supercritical fluids.