Rotary and displacement tuners for multistub cavities

Rotary and displacement tuners are described for multistub superconducting rf resonators. The effectiveness of these tuners is made possible because the resonators have low currents between their outer conductors and tuner elements. Computer simulations and experimental data show that the devices provide a tuning range up to 100kHz with a frequency resolution of about 1Hz. As well, only a small driving force is required allowing use of a low-backlash drive mechanism. The use of the rotary tuner is limited to the resonators with two loading elements such as the 2-stub quarter wave resonator, the conventional split loop resonator, and the 2-stub, half wave resonator. The displacement tuner is more versatile and can be used for any TEM-like quarter wave resonator or half wave resonator resonators with two or more loading elements.