A simplified method for calculating klystron performance

Designers of multicavity klystrons, faced with decisions in connection with the drift length/gain/efficiency compromise, can find theoretical treatment in an alarming variety of literature based both on the space-charge wave and the ballistic-electron-bunching theory. The only papers which effectively combine both theories are those of Webber [1], [2], in which a large number of curves representing considerable diversity of conditions have been computed. It has been found that, at the cost of a small error, a rearrangement of these results leads to useful universal curves (Fig. 1) enabling rapid decision making with regard to the effficiency/gain/ drift length compromise, in most situations. Gain calculations using Fig. 2 have given good agreement with practical results.