The continuous-wave breakdown of air and an air/carbon-tetrachloride mixture in uniform electric fields is examined, at frequencies between 3.5 and 30 Mc/s. The observations in air indicate that, if the pressure is reduced below atmospheric, the high-frequency breakdown voltage does not fall below the 50 c/s value until the amplitude of positive-ion oscillation has become much smaller than the gap width. This result is explained by a breakdown mechanism which depends both on positive-ion accumulation and on the variation of electron-ionization coefficient with electric field strength. Measurements by an air-stream method of a quantity related to pre-breakdown ionization in the gap appear to be consistent with the suggested breakdown mechanism. The h.f. measurements also exhibit the electron-diffusion type of breakdown, where a simple theoretical relationship must be satisfied for discharge initiation. A description is given of the effect of a small admixture of carbon tetrachloride vapour on the h.f. breakdown of air at reduced pressure. The vapour concentration was insufficient to affect 50 c/s breakdown. Where the electron-diffusion type of breakdown is normally operative, the h.f. breakdown strength increases by up to 50% when the vapour is present. The increase appears to be caused by electron attachment to vapour molecules.
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机译：检查了空气和空气/空气/四氯化碳混合物在均匀电场中的连续波击穿情况，频率在3.5到30 Mc / s之间。在空气中的观察结果表明，如果压力降低到大气压以下，则高频击穿电压不会降到50 c / s值以下，直到正离子振荡的幅度变得远远小于间隙宽度为止。该结果由击穿机理解释，该击穿机理既取决于正离子积累，也取决于电子电离系数随电场强度的变化。通过气流方法测量与间隙中的分解前电离有关的量似乎与建议的分解机理一致。 h.f.测量还显示出电子扩散类型的击穿，其中必须满足简单的理论关系才能引发放电。给出了四氯化碳蒸气的少量混合对h.f的影响的描述。减压下的空气分解。蒸气浓度不足以影响50 c / s的击穿。如果电子扩散类型的击穿正常发生，则h.f.存在蒸气时，击穿强度最多提高50％。这种增加似乎是由于电子附着在蒸气分子上引起的。
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