Study of noise in crossed-field electron guns

A theoretical program was carried out for determining the source of excess noise in crossed-field diodes. The theory was based on the assumption that the noise was due to instabilities arising from the continuous interaction between the reflection of electrons back to the cathode and the effective beam potential in front of the cathode. The generation of noise by the interaction was studied for unbounded parallel-plate short circuited diodes. The theory was carried out first in the absence of transit time effects and then later with the inclusion of transit time effects. Although the numerical results for the theory in the absence of transit time effects showed noise factors always less than unity, it is believed that numerical calculations yet to be carried out for the case including transit time effects will show noise factors in excess of unity and therefore the required condition for excess noise generation.