Amplitude model for beam oscillations in the main Linac of CLIC

To achieve the challenging goal of ultra-low emittance preservation in the main linac of CLIC, different techniques are used. The according algorithms often rely on an accurate, fast and efficient to compute model of the amplitude behavior of the beam oscillations in the beam line. In this paper such a model is developed, considering the accelerator design as well as the effect of filamentation. Filamentation is especially important, due to the high energy spread of the according beam and the large total phase advance of the lattice. Therefore a general model to describe filamentation is adapted to the properties of the beam in the main linac of CLIC. At the beginning of the linac, where made assumptions are not valid, this basic model is supported by a fit to simulation data. An accuracy evaluation of the produced data shows that the quadratic error is around 4 %. Therefore, the developed model delivers a fast and efficient procedure, to precisely predict the beam envelope behavior in the main linac of CLIC.