Lifetime issues of CLIC accelerating structures

The present parameters concerning the accelerating cavities of the future CLIC will be discussed in relation with the main phenomena which limit their accelerating field and efficiency. Particular attention will be given to the electrical breakdown and fatigue deterioration of materials. Both effects were observed in high power RF tests performed on the CTF3 facility and at other institutes collaborating to the project and in simpler laboratory setups. The results of the various experiments to predict and improve the lifetime and performance of the structures will be presented.