Applications of dielectric pads, novel materials and resonators in 1.5T and 3T MRI

\u3cp\u3eIn order to boost the performance of magnetic resonance imaging without increasing the static magnetic field, it is necessary to increase its intrinsic sensitivity. This allows a reduction in the scanning time, increased spatial resolution, and can enable low-field strength systems (which are much cheaper and can be used to scan patients with metallic implants) to have a higher signal-to-noise ratio (SNR) so that they are comparable to more expensive higher field strength systems. In this contribution, we demonstrate radiofrequency field enhancing and shaping devices based on novel materials, such as high permittivity dielectric structures and metamaterials. These materials can substantially enhance SNR, thus potentially increasing image resolution or allowing faster examinations.\u3c/p\u3

A Ferroelectric Fast Reactive Tuner (FE-FRT) to Combat Microphonics

A prototype Fast Reactive Tuner (FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a newly developed ultra-low loss ferro-electric material residing within the tuner. The tuner operates at room temperature, outside of the cryostat and coupled to the cavity via an antenna and co-axial cable. This technique allows for active compensation of microphonics, eliminating the need to design over-coupled fundamental power couplers and thus significantly reducing RF power particularly for low beam current applications. Modelling; simulation; and stability analysis, of the tuner; cavity; measurement system; and feedback loop, have been performed in the frequency and time domain, and are compared to the latest experimental results. The potential benefits of applying this techniques to ERLs, which are seen as one of the major use cases, are detailed both in general and with regards to specific projects. Ideas and designs for an improved next generation FRT are also discussed

A Ferroelectric Fast Reactive Tuner for Superconducting Cavities

A prototype FerroElectric Fast Reactive Tuner (FE-FRT) for superconducting cavities has been developed, which allows the frequency to be controlled by application of a potential difference across a ferroelectric residing within the tuner. This technique has now become practically feasible due to the recent development of a new extremely low loss ferroelectric material. In a world first, CERN has tested the prototype FE-FRT with a superconducting cavity, and frequency tuning has been successfully demonstrated. This is a significant first step in the development of an entirely new class of tuner. These will allow electronic control of cavity frequencies, by a device operating at room temperature, within timescales that will allow active compensation of microphonics. For many applications this could eliminate the need to use over-coupled fundamental power couplers, thus significantly reducing RF amplifier power