Data analysis method of the small samples and zero-failure data for space TWT accelerated life test

Space traveling wave tube (TWT) is one kind of microwave vacuum tube for communication, which must have high reliability, high power. The life of the space TWT is requested for a long lifetime of 10-15 years. In order to shorten the testing process, accelerated aging tests are performed at higher than normal operating temperature and currents of cathode. But in the process of the actual test, the cathode degradation is very slow, the test time is too long for all samples failing to get the lifetime data. In order to obtain the lifetime of the long life tube in a short time, it is necessary to investigate a new method which can evaluate the long lifetime through short-term working data. This paper introduced how to solve the zero-failure test data with small samples. With no failure data in data processing of life test, parameter degradation extrapolation method is used to obtain the failure life time. All the expected life of the sample was estimated of each test samples by least-square method for linear fitting and the goodness of fit and the significance testing was done.