RF Design and Experimental Test of a Quadrupole-Free X-Band TM_(01) Mode Launcher

摘要

In this work, we present a low-power RF characterization of a novel TM_(01) X-band mode launcher for the new generation of high-brightness RF photoinjectors. The proposed structure employs a fourfold symmetry in order to minimize both the dipole and the quadrupole fi elds that could cause an emittance growth in the early stages of the acceleration process. A “cold” model aluminum structure, comprising two mode launchers connected by a central 62 mm-long circular waveguide, was fabricated by milling aluminum blocks, assembled and measured in back-to-back confi guration. The low-power RF test, performed at the Istituto Nazionale di Fisica Nucleare Laboratori Nazionali del Sud (INFN-LNS), validated both the numerical simulations and the quality of the fabrication. An oxygen-free high-conductivity copper version of the device is being manufactured for high-power and ultrahigh- vacuum tests that are planned to be conducted at the Stanford Linear Accelerator Center (SLAC).