Studies of high efficiency interaction in traveling wave structures

We review the main experimental results on high power traveling wave amplifiers performed at Cornell; the highest efficiency achieved was 40% in a uniform periodic structure. For a higher efficiency, it is necessary to taper the output section. An analytical method to analyze and design quasi‐periodic output structure, is presented. It relies on the concept of interaction impedance matrix which is a generalization of the scalar interaction impedance in periodic structure. The efficiency is directly related to the largest eigen‐value of this matrix. We conclude with a brief discussion of the design of a new electron beam source for rf generation studies at low repetition rates.