BEAM-LOADING EFFECT IN THE NORMAL-CONDUCTING ILC POSITRON SOURCE PRE-ACCELERATOR

Significant positron bunch charge (several nC) in the ILC Positron Source (PS) results in high pulse beam loading for normal-conducting accelerating structures in Positron Pre-Accelerator (PPA). Time interval between bunches (∼ 300ns) is not negligibly small in comparison with accelerating structure time constant (rise time for Standing Wave (SW) or filling time for Traveling Wave (TW) options). As the result, beam loading effect has particularities bothfromstoredenergyaccelerationregimeand continuous beam loading one. Taking into account particular PPA beam structure, beam loading effect is estimated for the present ILC base line parameters, both for SW and TW PPA options. Possible solutionsforbeamloadingcompensation are discussed.