Fast Neutral Particles from Arc Cathode

Abstract

The rotating drum method was used to measure the velocity distribution in the vapor jet which emerges from the cathode region in a magnetically stabilized high-vacuum arc discharge maintained between cooled copper electrodes. To obtain sufficient detection sensitivity part of the cathode was made of radioactive copper. The number distribution of copper atoms deposited on the drum as a function of their velocity perpendicular to its surface was measured by a Geiger-Müller counter. An average of about 4×${10}^4$ cm/sec was found for the atomic beam velocity. It is suggested that misinterpretation of earlier observations has led to apparent velocities of up to ${10}^6$ cm/sec.