ITACA

This paper presents a method for the numerical simulation of the interaction between high charged bunches and axi-symmetric fields inside a cylindrical structure (RF cavity or wave guide). A computer code named ITACA (Integration of Transients in Axi-symmetrical Cavities for Accelerators) has been written on the basis of the method presented here. ITACA is an electromagnetic particle-in cell code able to study both the radial and axial motion of a bunch of particles moving through a cavity, and the propagation of the wake-field excited by the bunch itself inside the cavity. The code can inject the particles of the bunch into the resonant field of the accelerating mode present inside the cavity, making it possible to study the dynamics of the bunch in presence of all the relevant forces acting on it: the accelerating field, the space charge forces due to the self-field of the bunch and the wake-field excited by the interaction between the self-field of the bunch and the boundary condition imposed by the cavity surface. The computer code ITACA can handle, presently, axi-symmetrical fields and bunches, allowing to study monopole wake fields and their effects on the particles. The code has been designed in order to represent with accuracy the behavior of the fields and the dynamics of the particles: the first test indicate that this goal has been reached