Electrical breakdown in a collision-dominated plasma sheath

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Abstract
The field strength at a cathode is increased by the presence of a moving plasma due to the formation of a cathode sheath in which the ion mobility is reduced by the high neutral density in the cold boundary layer formed around the electrode. If further field intensification due to surface irregularities is included, the field at the cathode reaches and exceeds 3×107 V/cm, the field emission threshold. This field can be achieved at an applied voltage between electrodes of 40 V, which is well below the Paschen minimum. This effect was studied experimentally using the argon plasma generated in electromagnetically driven shock tube for wide ranges of plasma density (109−1016cm−3), degree of ionization, and initial pressure (0.1–10 Torr). The results should form the basis for prediction of the reignition characteristics in the all important period immediately (1–10 μsec) after the cessation of an arc.