Development Of An RF Transmission Line For Hyperfine Structure Studies At ISOLDE's VITO Beamline

This report details the design and prototyping of a custom radio frequency transmission line for the Versatile Ion-polarized Techniques On-line beamline at CERN’s ISOLDE facility. The project, conducted during a summer student internship, supports an upcoming upgrade to VITO that aims to enhance hyperfine structure spectroscopy of spin-polarized radioactive beams. Using CST Studio Suite, comprehensive electromagnetic simulations were carried out to optimize the geometry of the transmission line and its transition regions and internal support structures to improve the strength, homogeneity, and impedance matching of the RF field. The final design features a rectangular stripline with a precision-tapered transition region, a continuous Teflon support system, and refined conductor dimensions to minimize signal reflections. A prototype was constructed using water jet cut and 3D printed parts to validate the manufacturability and guide future implementation. Additionally, magnetic shielding composed of Mu-metal and iron was investigated to suppress ambient magnetic fields along the ion beam path, but it was determined that this shielding does not deliver the degree of magnetic shielding required for the experiment. This work provides the foundation for a robust and tunable RF delivery system integral to future precision measurements at VITO.