First tests of the machine protection system for CTF3

CTF3, the test facility for the CERN Linear Collider study, is supposed to be operated at intensities and energies which may cause harm to the machine. For this reason there is a need for a machine protection system (MPS). The aim of the article is to describe the preliminary version of this system and to show first results measured in the CTF3 machine at the end of the 2004 running period. The MPS is based on comparison of particle losses to a given threshold. As the MPS is required to stop the beam production within 1.5μs beam train pulse, very fast response needs to be achieved. Due to that, the losses are evaluated in real time as an amplitude attenuation of the beam current measured at two consecutive wall current monitors (WCM). When losses exceed given threshold, the beam-stop information is transmitted to the CTF3 gun interlock system. This causes inhibition of the beam production within the currently produced beam train. Manual actions are needed in order to recover from the beam-stop state of the MPS.