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Abstract

The increasing precision of Penning-trap experiments requires the development of novel cooling techniques to cool particles down to their motional ground state. One promising approach for ions that cannot be laser cooled is sympathetic cooling using a self-cooled electron cloud. This approach is currently under investigation in the ELCOTRAP experiment at the Max Planck Institute for Nuclear Physics (MPIK).
In this work, a superconducting B₀-tuning coil for ELCOTRAP is developed. This coil is used to shift the frequencies of the trapped electrons, thereby matching them to the cavity modes generated by the trap electrodes. The simulation shows that a two-coil geometry is the best option to achieve a strong and homogeneous magnetic field within the given boundary conditions of the experiment. Additionally, several methods for spot welding joints between NbTi wires are tested. No significant difference between a direct joint and a joint performed within a NbTi cylinder is observed. Furthermore, the wire diameter has no significant influence on the achievable current, which is determined to be over 2.5 A for a 0.5 mm wire diameter and over 1.4 A for a 0.3 mm wire diameter in a zero background field. Higher currents were not investigated. In an initial test using a 7 T background field, the tested joint lost its superconductivity for reasons that could not be futher investigated due to time limitations. The other joints were not tested in the strong background field.