Speaker
Description
Transverse deflecting cavities (TDCs) are important tools for beam diagnostics, as they imprint a time-dependent transverse kick on a charged bunch via radio-frequency (RF) electromagnetic fields in transverse modes. The polarization, defined by the orientation of the electric field, is a key figure of merit of a TDC, as it determines the deflection direction. In conventional TDCs, the polarization is fixed by separating the orthogonally degenerate modes using asymmetric cell geometries and by employing mode launchers that couple the input RF power to the desired mode. Recently, the requirements of multi-dimensional phase space reconstruction for advanced beam diagnostics have driven the development of novel TDCs with variable polarization. We therefore propose an S-band parallel-coupled TDC for the Shenzhen Superconducting Soft X-Ray Free-electron Laser, in which two chains of asymmetric cells providing horizontal and vertical deflections are independently fed by waveguides, allowing the polarization to be controlled by adjusting their relative amplitude and phase. This design offers several advantages, including high fabrication feasibility, single-frequency operation, compactness, and high shunt impedance. Two prototype structures have been successfully fabricated and tuned. The proof-of-principle experiment is planned to be conducted at Dalian Coherent Light Source.