ABSTRACT
Whichever mechanism might be employed for the generation or amplification of high-power microwaves, it is bound to involve the use of an electron beam. This is dictated by the ability of the beam to carry a large amount of power P b. If the average electron has a (relativistic) kinetic energy equal to (γ0 − 1)mc2 = eVb (with Vb being the accelerating, or “beam” voltage) and I b /e electrons cross any position per unit time (with I b being the beam current), then clearly P b = (γ0 − 1)mc2I b/e = V b I b. Even if the beam acceleration is accomplished by purely electrostatic means, the beam power can reach values approaching 1GW, hence any respectable value for the conversion efficiency can result in (output) microwave power well in the vicinity of, say, 10MW. (It is recalled that mc 2/e = 511kV, which enters in the correspondence between the relativistic factor γ0 and the beam voltage V b.)
