Scaling laws ofwake field effects due to gradient changes in the CLIC main LINAC

The main linac of CLIC is designed to maximize the transportable bunch charge, since this parameter determines the energy efficiency of the CLIC accelerating structures. The bunch charge is limited by short-range wake field effects, which increase the projected beam emittance. For the main linac cost optimisation, it is important to understand how the charge limit scales with the change of the gradient of the accelerating structures. In this paper, we determine such a scaling law via simulations studies. It is shown that from different possible scenarios, the charge limit for a lower gradient CLIC structure scales advantageous and a relatively high charge can be used.