A study of beam loading compensation on the Alternate Periodic Structure cavity of ILC e-driven positron source with an equivalent circuit model

The ILC is studying an e-drive method in which an electron beam of several GeV is incident on a metal target as a positron generation method. As a positron capture accelerator, we adopted a π/2 mode Alternate Periodic Structure cavity (APS cavity) that has a large diameter (2a = 60 mm) and can generate a high and stable acceleration gradient. In the e-driven method, electrons are generated in addition to positrons and the beam current is large, so compensation for them is a major issue. In this study, the transient state of the APS cavity was simulated by the equivalent circuit model, and the compensation of the beam loading effect was examined. (author)