Abstract: Spacetravellingwavetube（STWT）withlonglifeplaysanimportantroleonthepoweramplifierforsatellitecommunicationsystem.ThelifeoftheSTWTismainlyrestrictedbythecathodelife.InordertoensurethattheSTWTcanhavealonginorbitoperatingtime,itisnecessarytocarryoutplentyexperimentalresearchesonthelifeofSTWTcathode,andtopredictthelifeoftheSTWTcathode.Theaccumulatinglifetesttimeis1823080hoursfor50electronguns,thelongestlifetesttimeisover65411hours.Thelifepredictionmodelwasbuiltonthebasisofthechangeoftheworkfunctionduringthelifetime.Thepredictinglifeismorethan43yearswhenthecathodeisdrawnacurrentdensityof1A/cm²at960℃_b (℃_b: brightnesstemperature),itismorethan22yearsat980℃_b,  anditismorethan15yearsat1000℃_b.ThepredictinglifeshowsthatthelonglifeSTWTcathodecanmeettherequirementsofthesatellitecommunicationsystem.

Key words: spaceTWT, cathode, workfunction;emissioncurrentdensity, lifetest, lifepredictionmodel