17 research outputs found

    Overview of the JET results in support to ITER

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    Potential for development of innovative processes in the high-tech sector of the region's economy

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    The development prospects of innovative processes in the economy of the region, characterized by technological diversity and diversified specialization, are considered. The development areas were prioritized on the basis of the need to develop high-tech and knowledge-intensive sectors of the economy, which are the locomotives of growth for basic and infrastructural ones. Assessment of strategic opportunities was based on an analysis of the development trends of world commodity markets, taking into account the potential of the region and the competitive positions of industries. The development of world markets was considered in the aspect of “global challenges” and national trends in two types of challenges, which determined the possibilities for their development and impact on national and local markets. At the same time, the emergence of new conditions for the development of commodity markets, which must be taken into account in the evaluation processes. The phasing of the study is determined. The prospects for the development of a high-tech sector of the economy in the field of high production redistribution in the context of traditional and new markets are presented. A positioning map has been compiled and the transition from local (niche) competitiveness to international. Potential elements of the region's scientific and technical system in the form of R&D, production and consumption centers that accompany the process of technological development along the entire life cycle are identified

    Stem Cell Senescence: the Obstacle of the Treatment of Degenerative Disk Disease

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    An Analytical Expression for the Electric Field and Particle Tracing in Modelling of Be Erosion Experiments at the JET ITER-like Wall

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    A new analytical approximation for the electric potential profile in the presence of an oblique magnetic field and the analytical solution for the particle motion just before the impact with a plasma-facing surface are presented. These approximations are in good agreement with fluid solutions and the corresponding PIC simulations. These expressions were applied to provide effective physical erosion yields for Be, which have in a second step been used in ERO code simulations of spectroscopy at Be limiters of the JET ITER-like wall. These new analytical expressions lead to an increase of the effective physical sputtering yields of Be by deuteron impact up to 30% in comparison with earlier pure numerical simulations. (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

    Improved ERO modelling for spectroscopy of physically and chemically assisted eroded beryllium from the JET-ILW

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    Physical and chemical assisted physical sputtering were characterised by the Be I and Be II line and BeD band emission in the observation chord measuring the sightline integrated emission in front of the inner beryllium limiter at the torus midplane. The 3D local transport and plasma-surface interaction Monte-Carlo modelling (ERO code [18]) is a key for the interpretation of the observations in the vicinity of the shaped solid Be limiter. The plasma parameter variation (density scan) in limiter regime has provided a useful material for the simulation benchmark. The improved background plasma parameters input, the new analytical expression for particle tracking in the sheath region and implementation of the BeD release into ERO has helped to clarify some deviations between modelling and experiments encountered in the previous studies [4,5]. Reproducing the observations provides additional confidence in our ‘ERO-min’ fit for the physical sputtering yields for the plasma-wetted areas based on simulated data

    Ion cyclotron resonance heating for tungsten control in various JET H-mode scenarios

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    Ion cyclotron resonance heating (ICRH) in the hydrogen minority scheme provides central ion heating and acts favorably on the core tungsten transport. Full wave modeling shows that, at medium power level (4 MW), after collisional redistribution, the ratio of power transferred to the ions and the electrons vary little with the minority (hydrogen) concentration n H/n e but the high-Z impurity screening provided by the fast ions temperature increases with the concentration. The power radiated by tungsten in the core of the JET discharges has been analyzed on a large database covering the 2013-2014 campaign. In the baseline scenario with moderate plasma current (I p = 2.5 MA) ICRH modifies efficiently tungsten transport to avoid its accumulation in the plasma centre and, when the ICRH power is increased, the tungsten radiation peaking evolves as predicted by the neo-classical theory. At higher current (3-4 MA), tungsten accumulation can be only avoided with 5 MW of ICRH power with high gas injection rate. For discharges in the hybrid scenario, the strong initial peaking of the density leads to strong tungsten accumulation. When this initial density peaking is slightly reduced, with an ICRH power in excess of 4 MW,very low tungsten concentration in the core (∼10-5) is maintained for 3 s. MHD activity plays a key role in tungsten transport and modulation of the tungsten radiation during a sawtooth cycle is correlated to the fishbone activity triggered by the fast ion pressure gradient

    Disruption prediction with artificial intelligence techniques in tokamak plasmas

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    In nuclear fusion reactors, plasmas are heated to very high temperatures of more than 100 million kelvin and, in so-called tokamaks, they are confined by magnetic fields in the shape of a torus. Light nuclei, such as deuterium and tritium, undergo a fusion reaction that releases energy, making fusion a promising option for a sustainable and clean energy source. Tokamak plasmas, however, are prone to disruptions as a result of a sudden collapse of the system terminating the fusion reactions. As disruptions lead to an abrupt loss of confinement, they can cause irreversible damage to present-day fusion devices and are expected to have a more devastating effect in future devices. Disruptions expected in the next-generation tokamak, ITER, for example, could cause electromagnetic forces larger than the weight of an Airbus A380. Furthermore, the thermal loads in such an event could exceed the melting threshold of the most resistant state-of-the-art materials by more than an order of magnitude. To prevent disruptions or at least mitigate their detrimental effects, empirical models obtained with artificial intelligence methods, of which an overview is given here, are commonly employed to predict their occurrence—and ideally give enough time to introduce counteracting measures

    Thermal analysis of protruding surfaces in the JET divertor

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