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Magnetic Configuration (magnetic + configuration)
Selected AbstractsOptimization Study of ICRF Heating in the LHD and HSX ConfigurationsCONTRIBUTIONS TO PLASMA PHYSICS, Issue 6-7 2010S. Murakami Abstract Two global simulation codes, TASK/WM (a full wave solver) and GNET (a 5-D drift kinetic equation solver), are combined to simulate the ICRF heating in the 3D magnetic configuration. The combined code is applied to the ICRF minority heating in the LHD configuration. An optimization of the ICRF heating is considered in changing the magnetic configurations and the resonance surfaces in the LHD plasmas using GNET code. It is found that the heating efficiency is improved about 30% with the heating power of 10MW in the optimized heating scenario from that of the present standard off-axis heating scenario. Also the ICRF minority heating is studied in the HSX plasma and it is found that the ICRF heating of about 100kW is still effective to heat the plasma even , /a , 1/7.5 for tail ions (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Influence of Low-Order Rational Surfaces on the Radial Electric Field of TJ-II ECH PlasmasCONTRIBUTIONS TO PLASMA PHYSICS, Issue 6-7 2010O. Bondarenko Abstract Dynamic magnetic configuration scan experiments have been conducted in order to investigate the influence of the rotational transform on plasma rotation, radial electric field and turbulence. The main magnetic resonances (7/4 and 5/3 in this work) make a positive contribution to the local radial electric field, which depends on the plasma density and plasma radius. A local reduction in the level of density fluctuations due to the influence of low order rational surfaces is also observed. These results could explain local transport changes associated to low order rational surfaces observed in TJ-II ECH plasmas (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Multi-Fluid Modeling of Low-Recycling Divertor RegimesCONTRIBUTIONS TO PLASMA PHYSICS, Issue 3-5 2010R. D. Smirnov Abstract The low-recycling regimes of divertor operation in a single-null NSTX magnetic configuration are studied using computer simulations with the edge plasma transport code UEDGE. The edge plasma transport properties pertinent to the low-recycling regimes are demonstrated. These include the flux-limited character of the parallel heat transport and the high plasma temperatures with the flattened profiles in the scrape-off-layer. It is shown that to maintain the balance of particle fluxes at the core interface the deuterium gas puffing rate should increase as the divertor recycling coefficient decreases. The radial profiles of the heat load to the outer divertor plate, the upstream radial plasma profiles, and the effects of the cross-field plasma transport in the low-recycling regimes are discussed. It is also shown that recycling of lithium impurities evaporating from the divertor plate at high surface temperatures can reverse the low-recycling divertor operational regime to the high-recycling one and may cause thermal instability of the divertor plate (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The influence of dipolar interaction on magnetic properties in nanomagnets with different shapesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2010Ying Li Abstract With the Monte Carlo method, we investigate the magnetic properties of four nanomagnets of different shapes, i.e., the circular-shaped, the square-shaped, the elliptical, and the ring-shaped nanomagnets. A systematic study of the effects of the dipolar interaction on the magnetic configurations is performed in these nanomagnets, and further the coercive field and the remanence as a function of dipolar interaction are analyzed. The results show that the magnetic configuration and thus the magnetization reversal process of nanomagnets are dependent strongly on the strength of dipolar interactions. For the case of small dipolar interaction, the magnetization reversal process is mainly dominated by spin rotation, while the reversal transforms to the vortex nucleation and propagation formations with increasing dipolar interaction. Moreover, if the dipolar interaction is neglected in the calculation of the total energy, no clear difference is found among hysteresis loops of four nanomagnets with same areas, but the inclusion of dipolar interaction can lead to different hysteresis loops for nanomagnets with same areas but different shapes. This indicates that the dipolar interaction is important for accounting for the shape effect of the magnetic properties in nanomagnets. [source] Magnetotransport of lateral Py/Pt/Py spin valve devicePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 12 2007Giju Han Abstract Spin injection and accumulation have been investigated for Py/Pt/Py lateral spin valves with various channel length. Clear spin valve effects were found at antiparallel magnetic configuration of two ferromagnetic electrodes. The observation of memory effect suggests the spin valve effect observed in Pt channel is resulted from effective spin injection and detection. The magnitude of spin valve signal decreases as the channel length increases. The measurement yields that spin diffusion length and spin injection polarization of Pt channel is 120 nm and 18% at 5K. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Optimization Study of ICRF Heating in the LHD and HSX ConfigurationsCONTRIBUTIONS TO PLASMA PHYSICS, Issue 6-7 2010S. Murakami Abstract Two global simulation codes, TASK/WM (a full wave solver) and GNET (a 5-D drift kinetic equation solver), are combined to simulate the ICRF heating in the 3D magnetic configuration. The combined code is applied to the ICRF minority heating in the LHD configuration. An optimization of the ICRF heating is considered in changing the magnetic configurations and the resonance surfaces in the LHD plasmas using GNET code. It is found that the heating efficiency is improved about 30% with the heating power of 10MW in the optimized heating scenario from that of the present standard off-axis heating scenario. Also the ICRF minority heating is studied in the HSX plasma and it is found that the ICRF heating of about 100kW is still effective to heat the plasma even , /a , 1/7.5 for tail ions (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Extensions of the 3-Dimensional Plasma Transport Code E3DCONTRIBUTIONS TO PLASMA PHYSICS, Issue 1-3 2004A. Runov Abstract One important aspect of modern fusion research is plasma edge physics. Fluid transport codes extending beyond the standard 2-D code packages like B2-Eirene or UEDGE are under development. A 3-dimensional plasma fluid code, E3D, based upon the Multiple Coordinate System Approach and a Monte Carlo integration procedure has been developed for general magnetic configurations including ergodic regions. These local magnetic coordinates lead to a full metric tensor which accurately accounts for all transport terms in the equations. Here, we discuss new computational aspects of the realization of the algorithm. The main limitation to the Monte Carlo code efficiency comes from the restriction on the parallel jump of advancing test particles which must be small compared to the gradient length of the diffusion coefficient. In our problems, the parallel diffusion coefficient depends on both plasma and magnetic field parameters. Usually, the second dependence is much more critical. In order to allow long parallel jumps, this dependence can be eliminated in two steps: first, the longitudinal coordinate x3 of local magnetic coordinates is modified in such a way that in the new coordinate system the metric determinant and contra-variant components of the magnetic field scale along the magnetic field with powers of the magnetic field module (like in Boozer flux coordinates). Second, specific weights of the test particles are introduced. As a result of increased parallel jump length, the efficiency of the code is about two orders of magnitude better. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The influence of dipolar interaction on magnetic properties in nanomagnets with different shapesPHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 5 2010Ying Li Abstract With the Monte Carlo method, we investigate the magnetic properties of four nanomagnets of different shapes, i.e., the circular-shaped, the square-shaped, the elliptical, and the ring-shaped nanomagnets. A systematic study of the effects of the dipolar interaction on the magnetic configurations is performed in these nanomagnets, and further the coercive field and the remanence as a function of dipolar interaction are analyzed. The results show that the magnetic configuration and thus the magnetization reversal process of nanomagnets are dependent strongly on the strength of dipolar interactions. For the case of small dipolar interaction, the magnetization reversal process is mainly dominated by spin rotation, while the reversal transforms to the vortex nucleation and propagation formations with increasing dipolar interaction. Moreover, if the dipolar interaction is neglected in the calculation of the total energy, no clear difference is found among hysteresis loops of four nanomagnets with same areas, but the inclusion of dipolar interaction can lead to different hysteresis loops for nanomagnets with same areas but different shapes. This indicates that the dipolar interaction is important for accounting for the shape effect of the magnetic properties in nanomagnets. [source] | ||||||||||