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For the development of a DEMOnstration Fusion Power Plant the design of auxiliary heating systems is a key activity in order to achieve controlled burning plasma. The present heating mix considers Electron Cyclotron Resonance Heating (ECRH), Neutral Beam Injection (NBI) and Ion Cyclotron Resonance Heating (ICRH) with a target power to the plasma of about 50MW for each system. The main tasks assigned to the EC system are plasma breakdown and assisted start-up, heating to L-H transition and plasma current ramp up to burn, MHD stability control and assistance in plasma current ramp down. The consequent requirements are used for the conceptual design of the EC system, from the RF source to the launcher, with an extensive R&D program focused on relevant technologies to be developed. Gyrotron: the R&D and Advanced Developments on EC RF sources are targeting for gyrotrons operating at 240GHz, considered as optimum EC Current Drive frequency in case of higher magnetic field than for the 2015 EU DEMO1 baseline. Multipurpose (multi-frequency) and frequency step-tunable gyrotrons are under investigation to increase the flexibility of the system. As main targets an output power of significantly above 1MW (target: 2MW) and a total efficiency higher than 60% are set. The principle feasibility at limits of a 236GHz, conventional-cavity and, alternatively, of a 238GHz coaxial-cavity gyrotron are under investigation together with the development of a synthetic diamond Brewster-angle window technology. Advanced developments are ongoing in the field of multi-stage depressed collector technologies. Transmission Line (TL): Different TL options are under investigation and a preliminary study of an evacuated quasi-optical multiple-beam TL, considered for a hybrid solution, is presented and discussed in terms of layout, dimensions and theoretical losses. Launcher: Remote Steering Antennas have been considered as a possible launcher solution especially under the constraints to avoid movable mirrors close to the plasma. With dedicated beam tracing calculations, the deposition locations coverage and the wave absorption efficiency have been investigated, considering a selection of frequencies, injection angles and launching points. An option for the EC system structure is proposed in clusters, in order to allow the necessary redundancy and flexibility to guarantee the required EC power in the different phases of the plasma pulse. Number and composition of the clusters are analysed to have high availability and therefore maximum reliability with a minimum number of components.

Microwave tomography (MWT) is exploited for the detection of haemorrhagic stroke by using a nonlinear iterative imaging algorithm. An anatomically realistic two-dimensional (2D) head model is simulated using a finite difference time-domain numerical solver. By using an iterative optimisation algorithm based on the GaussNewton approach, the head model with an artificially embedded stroke region modelled as blood is successfully reconstructed through a blind reconstruction procedure (i.e. no a priori information about the shape or the dielectric properties of the model is assumed). It is observed that beginning from a homogeneous guess similar to the background material, right after the first iteration the shapes of the layers are clearly distinguished and the values of the dielectric properties converge to the actual values after only 10 iterations.Introduction: A stroke is a rapid damage in the brain tissue due to an interruption in the blood flow. Stroke can be classified into ischaemic and haemorrhagic. The ischaemic stroke is caused by a blood vessel, whereas the haemorrhagic stroke is due to a vessel rupturing and bleeding into the surrounding area.Conventional imaging techniques for stroke detection are magnetic resonance imaging and computed tomography (CT-scan). Although they have proved to be efficient in detecting a stroke, there are drawbacks associated with both the techniques that have motivated the research for alternative or complementary techniques. Since a stroke is an emergency problem, to avoid loss of time, the favourite imaging system should have the potential of being implemented in a portable device available in emergency centres and even in ambulances. In this case, the diagnosis can be initiated while the patient is underway to a hospital.Microwave imaging offers a portable, cost-effective and safe imaging procedure for medical applications [1] and it can be regarded as an alternative or complementary imaging technique. Microwave tomography (MWT) is a promising imaging technique that provides a quantitative map of the dielectric properties of the object of interest, i.e. complex permittivity [2]. In fact, the tissues affected by disease exhibit other dielectric properties than the healthy tissues and this is the very basis MWT works upon.The human head is quite a high-contrast target consisting of both high-water-content (e.g. grey matter) and low-water-content tissues (e.g. skull) and therefore it is a complex imaging target for MWT. In [3], a simplified human head model has been imaged by the MWT approach. In this Letter, an anatomically realistic two-dimensional (2D) head model extracted from [4] with an artificially embedded haemorrhagic stroke is measured in an finite difference time-domain (FDTD) solver by using 24 ideal point source antennas surrounding the model in the form of a square array. By using a nonlinear iterative reconstruction program based on the Gauss-Newton optimisation implemented in C + + , the head model is successfully reconstructed after 10 iterations starting fr...

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Multistage Depressed Collectors (MDCs) are nontrivial for high-frequency gyrotrons. A basic conceptual design of an E Â B MDC using azimuthal electric fields was proposed in Part I of this series. In the present work, several upgraded design proposals based on the basic one will be elaborated. These proposals will significantly reduce the back-stream of electrons, which was the main drawback of the basic design proposal. Another upgraded design proposal will shrink the length and maximal radius of the MDC to be only a fraction of its full-length version. A conceptual design of the final MDC proposal will be given at the end.Published under license by AIP Publishing. https://doi.

A newly developed tool to simulate a tokamak full--discharge is presented. The tokamak "flight--simulator" Fenix couples the tokamak control system with a fast and reduced plasma model, yet realistic enough to take into account several of the plasma non--linearities. Distinguishing feature of this modeling tool is that it only requires the Pulse Schedule (PS) as input to the simulator. The output is a virtual realization of the full discharge, which time traces can then be used to judge if the PS satisfies control/physics goals or needs to be revised. This tool is thought for routine use in the control--room before each pulse is performed, but can also be used off--line to correct PS in advance, or to develop and validate reduced models, control schemes, and in general the simulation framework.

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