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The statistical distribution of the sparking time lag is studied theoretically. Especially the effects of the electrons remaining in the space near the cathode under over voltage to a continuously illuminated gap are discussed in detail.

The pulseless corona of a negative point to a plane gap in air was examined. At high pressures it behaves as a kind of abnormal glow discharge. By increasing the corona current, the reduced current density on the cathode surface increases from 267 µA/(cmTorr)2 at the onset to 490 µA/(cmTorr)2just before the spark breakdown. The gas temperature of the negative glow shows also an increase in the range of 1050~1170 K with increasing corona current. The current distributions on the plane electrode are similar for different values of the gap length. In the space gap near the plane electrode, at the moment of transition is equal to or greater than the electron attachment coefficient. This result can be used as a criterion for the occurrence of a transition from the negative pulseless corona to spark breakdown.

An investigation has been made of the photon pulses and the associated current pulses in the pre-onset stage of a positive point corona in air at atmospheric pressure. The transition from burst pulses to streamer pulses is discussed.

By using the general formulas derived from the analysis in a previous paper, calculations are made of the development of electronic and ionic space charges, the growth of space-charge-distorted field, the buildup of current, and the gain in ionization integral due to the field distortion in the transient Townsend discharge. On the basis of these data, two types of Townsend-mechanism spark breakdown are discussed. (auth)

Transient Townsend discharge in parallel plane electrodes is restricted by the wall at low pressure, but it has a discharge path narrower than the electrode area at high pressure. The present paper deals with the buildup of the transient Townsend discharge of non-uniformly lateral distribution due to electronic and ionic diffusion. The general solutions for the electronic and positive-ionic charge distributions are given and the characteristic constants, by which wall effects on the buildup of the discharge can be estimated, are decided.

Theoretical investigations are given on the statistical distribution functions of the number of electrons in a series of electron avalanches initiated by a high‐energy particle at an applied voltage below the sparking voltage. The distribution functions are derived for the electron avalanches started by initial electrons generated at the cathode, using the Poisson and geometric distributions for the initial electrons. Furthermore, the distribution function is obtained for the electron avalanches started by a single initial electron generated at any place in a discharge gap.

Behavior of plasma expanding along a uniform guide field and the thermalization processes of the kinetic energy of the plasma flow by shock wave due to a magnetic barrier are investigated with the parameter of initial plasma. Longitudinal expansion of a plasma in a uniform guide field is accompanied by a decrease in the density and the temperature. The decrease in the temperature is smaller than the density decrease. This seems to be in agreement with a model, which has been applied on Bille en Têté experiment. Shock wave propagates in the upstream direction accompanying the in creasing of the temperature and the density behind the shock front. This phenomenon is clearer in the case of lower density and higher temperature plasma.