IMPROVING THE RELIABILITY OF SPACE-USE TRAVELING-WAVE TUBES AND CONFIRMING THE IMPROVEMENT

This study establishes the design method for the high reliability for the space-use traveling wave tube (TWT) and presents the verification experiment of the high-reliability performance for the case of TWT to be installed on CS-3, as an example. Based on the relation between the cathode current density and the lifetime, which is derived from the d egradation theory of the coated impregnated cathode, the convergence r atio of the electron gun and the cathode current density are optimized . A method is presented which realizes the long-life and highly reliab le TWT, by the high-reliability design and the screening based on theo ry. To verify the high-reliability design, the wear-out failure distri bution is estimated by the accelerated temperature test; and the failu re rate due to the random failure is estimated from the actual in-orbi t data. As a result of analysis of this mixed Weibull distribution, it is shown that the failure rate of 1000 fit, which is set as the desig n goal, can be achieved for 7 years of planned working period. It is s hown also that by employing the high-reliability design, the failure r ate of 1000 fit or less can be achieved even if the working period of 10 years is defined.