PURPOSE: To obtain a long-lived travelling-wave tube along with the improvement of the reliability by programming a circuit for controllig anode voltage and beam shaping voltage into a travelling-wave tube device.

CONSTITUTION: A voltage control device 19 that comes in the optimum condition in lapse of time by a program is connected with an electron beam shaping electrode 10 and an anode 11, and this voltage control device 19 can be previeously controlled in various ways by a program utilizing a microcomputer, etc. Namely, many data changing with lapase of time about a cathode that was previously obtained are simultated by a computer in order to obtain the orbital and current of an electron beam stabilized in lapse of time, enableing the control of beam shaping electrode voltae and anode voltage to be programmed. Hereby, it is possible to improve the lift and reliability of a device that were frequency limited due to the aging deterioration of electron beam discharge characteristics of the cathode.