Beam Dynamics in the Accelerating RF Structures of the CTF2 Drive Beam Simulated with PARMELA Particle Tracking Program

The behavior of the CTF2 drive beam is studied through the first elements of the line for a bunch train of 48'10nC. Simulations were realised with the PARMELA program which tracks particles through different RF and magnetic elements. Space charge and beam loading in RF structures are included in the calculations, but not the wakefields. In this note, all the beam, RF and magnetic parameters are chosen to approach the operational settings of the CTF2 at the end of 98 and the beginning of 99. Two configurations are reported and compared. The first is chosen to describe the Nov. 98 experimental layout. The second one with a booster section is proposed to improve the beam characteristics. The PARMELA beam generation is discussed. Then, the fields in the HCS sections are studied, a purely standing wave in the couplers is put in evidence and a model of the HCS is deduced and tested for the PARMELA simulations. The RF effects of the HCS section on the beam dynamics are demonstrated, in particular the critical focusing of the input HCS1 coupler. The simulations of the two layouts focus also on train transmission, beam envelopes and energy spreads inside the bunches and over the train.