Showing papers by "V. Igochine published in 2005"
TL;DR: In this article, an integrated scenario has emerged which extrapolates to a 50% improvement in n T τ or a 30% reduction of the required current when compared with the ITER base-line assumptions, with moderately peaked electron and controllable high-Z density profiles.
Abstract: Significant progress has been made on ASDEX Upgrade during the last two years in the basic understanding of transport, in the extension of the improved H-mode in parameter space and towards an integrated operating scenario and in the development of control methods for major performance limiting instabilities. The important features were the understanding of particle transport and the control of impurity accumulation based on it, the satisfactory operation with predominantly tungsten-clad walls, the improved H-mode operation over density ranges and for temperature ratios covering (non-simultaneously) the ITER requirements on ν*, n/nGW and Te/Ti, the ELM frequency control by pellet injection and the optimization of NTM suppression by DC-ECCD through variation of the launching angle. From these experiments an integrated scenario has emerged which extrapolates to a 50% improvement in n T τ or a 30% reduction of the required current when compared with the ITER base-line assumptions, with moderately peaked electron and controllable high-Z density profiles.
30 citations
TL;DR: Gunter et al. as discussed by the authors analyzed the role of stochastization of magnetic field lines in fast reconnection phenomena occurring in magnetized fusion plasma and found that fast reconnections observed during amplitude drops of the neoclassical tearing mode instability in the frequently interrupted regime can be related to stochasticization.
Abstract: The role of stochastization of magnetic field lines in fast reconnection phenomena occurring in magnetized fusion plasma is analyzed. A mapping technique is applied to trace the field lines of toroidally confined plasma where the perturbation parameter is expressed in terms of experimental perturbation amplitudes determined from the Axially Symmetric Divertor Experiment (ASDEX) Upgrade tokamak [S. Gunter, C. Angioni, M. Apostoliceanu et al., Nucl. Fusion 45, S98 (2005)]. It is found that fast reconnection observed during amplitude drops of the neoclassical tearing mode instability in the frequently interrupted regime can be related to stochastization.
10 citations
01 Sep 2005
TL;DR: In this paper, the authors have demonstrated clear progress in ITER relevant plasma operation scenarios and showed that the operation space of the improved H-mode (advanced tokamak scenario) is enlarged in safety factor 3lesq95 les5 and density 0.4lesne/nGWles0.9.
Abstract: ASDEX Upgrade has demonstrated clear progress in ITER relevant plasma operation scenarios. Successful operation with about 70% Tungsten clad first wall is shown. The operation space of the improved H-mode (advanced tokamak scenario) is enlarged in safety factor 3lesq95 les5 and density 0.4lesne/nGWles0.9. The performance can clearly exceed the ITER reference value. At high densities type-II ELMs mitigate the peak power load in the divertor. A similar effect is achieved by increasing the type-I ELM frequency by shallow pellet injection or cyclic vertical plasma motion. Off-axis neutral beam current drive leads at low powers to a clear current density profile modification. Sawtooth tailoring by electron cyclotron current drive (ECCD) can prevent the growth of neoclassical tearing modes (NTM). (3, 2) and (2, 1) NTMs excited at high plasma pressure can be stabilized by ECCD at moderate power levels. Narrow ECCD absorption profiles are more effective than broad ones
1 citations