Abstract
These investigations were conducted to measure the prebreakdown current and breakdown voltage between aluminium, copper, stainless steel, niobium and gold electrodes in vacuum and uniform fields at room, liquid nitrogen and liquid helium temperatures. The range of electrode spacings for the current measurements was 0·1-4 mm and for the breakdown voltages was 0·1-1·8 mm. The results showed that the current decreased with decreasing electrode spacing and decreasing cathode temperature. They also showed that the breakdown voltage increased with increasing electrode spacing and decreasing cathode temperature. It was shown that the prebreakdown currents obeyed a cold-cathode emission law analytically similar to the Fowler-Nordheim relation and that the changes in values could be explained by changes in the field intensification factor and emitting area. The breakdown voltages indicated that the same mechanism prevailed at all spacings and temperatures and suggested that breakdown was initiated by the cold-cathode emission currents causing an instability at either the anode or the cathode.
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