Wake fields in HCS accelerator and CTS power line of the CLIC Test Facility (CTF II): simulation with program wake

One of the two parallel beam lines of the CTF II, (the 'Drive Beam') is providing the other (the accelerator) with 30 GHz power. Experimentation was performed in 98 and later with a CTF layout to study acceleration of a train of bunches with beam loading compensation, bunch length compression and 30 GHz conversion of the Drive Beam power [1]. This conversion is limited by the difficulty of transmitting the beam through the structures extracting the beam power (CTS). A large transverse wake loss factor is associated with the necessary high longitudinal wake loss factor in CTS. Therefore the limitation of transmission should come mainly from transverse wakes in CTS. Dynamics in HCS and in the bunch compression device was studied with codes GPT [2] and PARMELA [3], [4] using beam parameters input derived from calculations of the beam in the RF gun with code MAFIA. Code WAKE is used to verify that the influence of the wake-fields in HCS is small, to follow the beam along the 4 CTS of the drive linac, and to give results for the transmission, which can be compared with the experimental ones.