Optimization of positions and currents of tokamak poloidal field coils using genetic algorithms

Plasma equilibrium geometry has a great influence on the confinement and magnetohydrodynamic stability in tokamaks. The poloidal field (PF) system of a tokamak should be optimized to support the prescribed plasma equilibrium geometry. In this paper, a genetic algorithm-based method is applied to solve the optimization of the positions and currents of tokamak PF coils. To achieve this goal, we first describe the free-boundary code EQT Based on the EQT code, a genetic algorithm-based method is introduced to the optimization. We apply this new method to the PF system design of the fusion-driven subcritical system and plasma equilibrium geometry optimization of the Experimental Advanced Superconducting Tokamak (EAST). The results indicate that the optimization of the plasma equilibrium geometry can be improved by using this method.

Design of triangular lattice photonic crystals using genetic algorithms

Genetic Algorithms (GAs) were used to design triangular lattice photonic crystals with large absolute band-gap. Considering fabricating issues, the algorithms represented the unit cell with large pixels and took the largest absolute band-gap under the fifth band as the objective function. By integrating Fourier transform data storage mechanism, the algorithms ran efficiently and effectively and optimized a triangular lattice photonic crystal with scatters in the shape of 'dielectric-air rod'. It had a large absolute band gap with relative width (ratio of gap width to midgap) 23.8%.

Effects of gamma irradiation and air annealing on Yb-doped YAlO3 single crystals

The effects of gamma irradiation on as-grown 5 at% Yb:YAlO3 (YAP) and air annealing on gamma-irradiated 5 at% Yb: YAP have been studied by the difference in the absorption spectra before and after treatment. The gamma irradiation and air annealing led to opposite changes of the absorption properties of the Yb: YAP crystal. After air annealing, the gamma-irradiation effects were totally removed over the wavelength range 390-800 nm and the concentrations of Fe3+ and Yb3+ were slightly increased. For the first time, the gamma-irradiation-induced valence changes between Yb3+ and Yb2+ ions in Yb: YAP crystals have been observed. (c) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of gamma-irradiation and air annealing on Yb-doped Y3Al5O12 single crystal

The effects of gamma-irradiation on the air-annealed 10 at.% Yb:Y3Al5O12 (YAG) and air annealing on the gamma-irradiated 10at.% Yb:YAG have been studied by the difference absorption spectra before and after treatment. The gamma-irradiation and air annealing led to opposite changes of the absorption properties of the Yb:YAG crystal. After air annealing, the gamma-irradiation induced centers were totally removed and the concentration of Fe3+ and Yb3+ were lightly increased. For the first time, the gamma-irradiation induced valence changes between Yb3+ and Yb2+ ions in Yb:YAG crystals have been observed. (C) 2007 Elsevier B.V. All rights reserved.