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Abstract-Experimental results using a step-frequency tunable D-band gyrotron are reported. The short-pulse (~3 ms) gyrotron is equipped with an elliptically brazed CVD diamond Brewster angle output window. It is designed for the operation in the frequency range from 111.6 GHz up to 165,7 GHz. Operating parameters for 10 different frequencies corresponding to an equal number of different cavity operating modes has been measured. A minimum output power of 830 kW and a peak output power of 1.3 MW have been realized. For all frequencies the parameters of the RF beam generated by the internal quasioptical converter, such as fundamental Gaussian contents and beam waist, are sufficiently good to allow an efficient coupling of the RF power out of the window. This is the first time a diamond Brewster angle window has been used in a high power gyrotron (~ 1 MW). Such a system offers the path to a simple and compact window solution for high power broadband applications using gyrotrons.

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.

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Absiract -Various methods of utilizing the UWB spectrum have been developed to date, characterized by specific modulation schemes, such as pulse position, pulse amplitude or bi-phase modulation. A new method emerging today utilizes a multi-band appmacb, where information is encoded in multiple RF subbands at s t a g e d time, each occupying 500MHz bandwidth. A description of multi-band modulation schemes for UWB is included in the paper.The long term vision for UWBbased products is to enable personal devices with integrated wireless connectivity. This requires 110, 200 and 480Mbps at lOm, end reasonably low power consumption. UWB requires CMOS designs in order to achieve low power and low cost integration with other devices, and to fulfill the vision of integrated connectivity.One of the design challenges is the high operating frequencies (3.1-10.6CHz), an additional challenge is that low Q systems are more sensitive to parasitic% especially in pads and wire bonds. Same UWB receiver architectures require good isolation among subbands. They also require quick switching between subbands at dillerent fquencies. Example transmitter and receiver architectures. are described in the paper.