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In high-power fusion gyrotrons, the maximum heat-load on the wall of the interaction section is in the order of 2 kW/cm2, which is the major limiting technological factor for output power and pulse-length of the tube. The ongoing gyrotron development demands a very effective cavity cooling system for optimum gyrotron operation. In this work, the experimental investigation of a mini-channel cavity cooling using a mock-up test set-up is described. The mock-up test set-up will be used to experimentally validate the predictive simulation results and verify the mini-channel cooling performance. It is crucial for validation of the mini-channel cooling properties to determine the amount of the heat load introduced in the cavity wall by an induction heater. In order to estimate that heat load, full 3D electromagnetic simulations have been performed using the CST Studio Suite® software. A suitable calibration factor for the load deposited in the mock-up inner wall is identified after numerical investigation by a 3D thermal model. Calorimetry measurements are performed and the experimental results are compared with the simulation results obtained with a 3D thermal-hydraulic model, using the commercial software STAR-CCM+. When the calibration factor is applied, the experimental calorimetry is well reproduced by the simulations.

We designed a novel PET insert based on monolithic LYSO crystals. From our first evaluation, we can conclude that sub-millimeter detector spatial resolution, combined with accurate photon DOI determination, make it possible to acquire high resolution reconstructed images. This enables us to combine simultaneously high resolution and sensitivity PET with high field preclinical MRI to extract simultaneously complex data capable to provide both anatomical and molecular information and to dynamically follow non-invasively animal models of different pathologies with no compromise in performance of each imaging modality. Each detector head (8 in total) mounts a 50×50×10 mm3 LYSO block coupled to a high density array of SiPMs. The readout used on each detector returns the X and Y projections of the scintillation light distribution. The PET geometry defines an axial and transaxial FOV of 46 mm (1 ring system) and 80 mm, respectively. The PET is surrounded of carbon fiber to avoid RF field interferences into the PET electronics without generating eddy currents affecting the MRI integrity. Current results show a PET resolution nearing 750 um (using Derenzo-like phantoms) simultaneously working with the MRI. In-vivo pilot tests of the PET insert system at the KU-Leuven (Belgium) inside a 7 T Bruker MRI equipped with a BGA 20S-HP gradient coil have shown the capability of both PET and MRI to simultaneously work providing high resolution PET and MRI images.