Lead-free (Na 0:5 K 0:5 )NbO 3 (NKN) powders and thin films were fabricated from stoichiometric (Na/K ¼ 50=50), 4 mol % excess (52/52, 53/51, and 55/49), and 10 mol % excess (55/55, 56/54, 58/52, and 60/50) precursor solutions by the sol-gel process. The NKN55/55 powder heat-treated at 800 C showed an orthorhombic phase and rectangular grains whose size was estimated to be about 300 nm. With increasing Na/K ratio, grain size increased to about 1 mm and the cubic-tetragonal (T c ) phase transition peak emerged at 392 C in a differential thermal analysis (DTA) curve. On the other hand, single-phase NKN thin films were fabricated at 600 C from the (Na,K)-excess precursor solutions (58/52 and 60/50). In particular, the NKN58/ 52 thin film showed a low leakage current density (10 À7 A/cm 2 at 40 kV/cm), and the maximum polarization P max and dielectric constant " r at 1 kHz were 9.1 mC/cm 2 and 725, respectively.

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A tracer-encapsulated solid pellet (TESPEL) injection system for the TJ-II stellarator was recently developed. In order to reduce the time and cost for the development, we combined a TESPEL injector provided by National Institute for Fusion Science with an existing TJ-II cryogenic pellet injection system. Consequently, the TESPEL injection into the TJ-II plasma was successfully achieved, which was confirmed by several pellet diagnostics including a normal-incidence spectrometer for monitoring a tracer impurity behavior.

The new code version of EMC3, which can deal with non‐uniform cross‐field transport coefficient, is benchmarked with analytical problem and a finite difference method. It has been confirmed that for arbitrary spatial change of the transport coefficient the error is suppressed below tolerable level for the purpose of comparison with experiments. The first implementation of the new code in LHD stochastic layer shows existence of significant change of cross‐field transport in radial direction. The location of the change corresponds to the boundary between long flux tubes region and the edge surface layers (where long and short flux tubes co‐exist, i.e. laminar zone). (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

A 20 barrel solid hydrogen pellet injector, which is able to inject 20 cylindrical pellets with a diameter and length of between 3.0 and 3.8 mm at the velocity of 1200 m/s, has been developed for the purpose of direct core fueling in LHD (Large Helical Device). The in situ pipe gun concept with the use of compact cryo-coolers enables stable operation as a fundamental facility in plasma experiments. The combination of the two types of pellet injection timing control modes, i.e., pre-programing mode and real-time control mode, allows the build-up and sustainment of high density plasma around the density limit. The pellet injector has demonstrated stable operation characteristics during the past three years of LHD experiments.

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