Estimation of acceptable beam trip frequencies of accelerators for ADS, 4; Consideration of the probability density function for accidental interruptions of klystrons

Takei, Hayanori   ; Furukawa, Kazuro*; Yano, Yoshiharu*; Ogawa, Yujiro*

Experiences with existing high-power proton accelerators have shown that frequent beam trips have occurred. The reasons for occurring the beam trips may be classified into two broad categories: one is the failure and/or the repair/replacement of accelerator components, and the other is preventive interruption to protect accelerators against failures. In the former case, the beam-trip frequency can be evaluated based on a reliability database for accelerator components. On the other hand, in the latter case, the beam-trip frequency was not evaluated because the reliability database has not yet been established. A principal reason for the lack of this reliability database is the inconsistency of data collection and analysis methods among laboratories. In the present study, the probability density function that accidental interruptions occurred in the klystron system of an electron/positron injector linac at the High Energy Accelerator Research Organization (KEK) was evaluated based on the reliability engineering method, in order to build the reliability database using the uniform data collection and analysis method. As the result, the probability density function might be not the exponential distribution. As this result is obviously different from the traditional result, it is necessary to re-evaluate the probability density function of the accelerator component at other accelerator facilities by use of the present method.