A CONCEPT OF A WIDE-APERTURE KLYSTRON WITH RF ABSORBING DRIFT TUBES FOR A LINEAR COLLIDER

This paper is devoted to a problem of the optimal design of the electr odynamic structure of the X-band klystron for a linear collider. It is shown that the optimal design should provide a large aperture and a h igh power gain, about 80 dB. The most severe problem arising here is t hat of parasitic self-excitation of the klystron, which becomes more c omplicated at increasing aperture and power gain. Our investigations h ave shown that traditional methods for suppressing the self-excitation become ineffective at the desired technical parameters of the klystro n. In this paper we present a novel concept of a wide aperture klystro n with distributed suppression of parasitic oscillations. Results of a n experimental study of the wide-aperture relativistic klystron for VL EPP are presented. Investigations have been performed using the drivin g beam of the JINR LIA-3000 induction accelerator (E = 1 MeV, I = 250 A, tau = 250 ns). To suppress self-excitation parasitic modes we have used the technique of RF absorbing drift tubes. As a result, we have o btained design output parameters of the klystron and achieved a level of 100 MW output power.