Microwave shot noise in electron beams and the minimum noise factor of travelling wave tubes and klystrons

A theorem recently proposed by J. R. Pierce concerning the intrinsic noise of electron streams is verified for electron beams originating in thermionic diodes under arbitrary conditions. The theorem is applied to the calculation of the minimum noise factor of klystrons and travelling wave tubes which is found to be 6 db. The treatment of partition noise is made possible by a generalization of the theorem.