[en] Effect of a poloidal electric field on the electron cyclotron current drive is studied in a tokamak geometry. A general discussion of its influence on the electron phase-space dynamics and current drive efficiency is presented. It is shown that the modification to the current drive efficiency increases as the heating location is moved out in the major radius. It is concluded that the modification is only moderate to insignificant (<10% for low magnetic field side heating and <3% for high field side heating) for a poloidal electrostatic potential variation of order inverse aspect ratio under an efficient current drive

[en] A significantly improved analytic understanding of the extrinsically driven diffusion process is presented in a nonlinear dynamical system in which the phase space is divided into periodic two-dimensional tiles of regular motion, separated by a connected separatrix network (web) [previously studied by A. J. Lichtenberg and Blake P. Wood, Phys. Rev. Lett. >62, 2213 (1989)]. The system is represented by the usual 'kicked Harper map' with added extrinsic noise terms. Three different diffusion regimes are found depending upon the strength of the extrinsic perturbation l relative to the web and regular motions. When the extrinsic noise is dominant over the intrinsic stochasticity and the regular rotation motions in the tile, diffusion obeys the random phase scaling l². When the extrinsic noise is dominant over the intrinsic stochasticity, but weaker than the regular rotation motion, the diffusion scales as lK^1/2, where K is the strength of the intrinsic kick. These findings agree well with numerical simulation results. When the extrinsic noise process is weaker than the stochastic web process, we analytically reproduce the well-known numerical result: The web diffusion is reduced by the ratio of phase-space areas of intrinsic to extrinsic stochasticity

[en] This paper presents the results of a study on the optical transmittance of hot-pressed magnesium fluoride dome and disk blanks in terms of the optical anisotropy caused by the material texture. The issues involving the hot-pressing dome texture are discussed using the X-ray diffraction pattern method. It is shown that the texture is produced by the magnesium fluoride compaction during the hot-pressing process due to the plastic flow in the individual micrograins. Further details on the textural features of hot-pressed magnesium fluoride dome sample can also be obtained using the interference polarization pattern method. A comparison of the transmittance in the two principal directions in a hot-pressed disk sample strongly suggested that a reduction in the birefringent scattering loss resulting from the optical anisotropy is mainly responsible for the high transmittance

[en] The influence of annealing on the AgGaS₂ films grown by pulsed laser deposition has been investigated. The X-ray diffraction results show the AgGaS₂ films were found with preferential orientation (1 1 2) normal to the surface and silver droplets were diminished after the post-annealing. Photoluminescence (PL) measurements reveled the exciton energy is slightly red shifted that is possibly due to the thermal strain effect. The binding energy of the shallow donors is ∼28 meV determined from temperature dependent PL spectra. In addition, the A-exciton and the B/C-exciton could be observed in the transmittance spectra at room temperature

[en] Conclusions: • WDMApp is a leading priority of the fusion community and will deliver a computational tool of unprecedented power and versatility. • We have focused here on two primary goals: (1) Coupling of core gyrokinetic code (GENE and GEM) and edge gyrokinetic code (XGC), and performance of the coupled code with FOM > 50 (2) Development of a user-friendly extensible framework EFFIS 2.0 for code-coupling in WDMApp. • The science is potentially transformational, and compute power will help realize Hawking’s vision for fusion in the 21st century.

[en] When the thickness of a metallic film is in the nanometre range, electrons in the film as well as those transmitting through the film can both manifest the quantum size effect (QSE). For the former, electrons are confined in the quantum well of a metal film to form quantum-well states. For the latter, electrons scattered by the quantum well in the film can bring about the phenomenon of transmission resonance. Scanning tunnelling microscopy (STM) combined with spectroscopy is a powerful tool to explore these two kinds of QSE. In this paper, we review our recent studies on the QSE of thin Pb and Ag films by using STM. We demonstrate that the formation of the quantum-well states in the Pb film can significantly affect the morphology, thickness, growth process and electronic structures of Pb films. On the other hand, the transmission resonance can be observed on the Ag film with Z-V spectroscopy in STM. The energy level of the transmission resonance varies with the film thickness and can be shifted by the electric field. Moreover, in the studies of transmission resonance, it is unavoidable to observe the standing-wave states, i.e. Gundlach oscillations, which are the QSE in the tunnelling gap. We have also discovered that the Gundlach oscillation can be exploited to measure the work function of thin metal films with very high precision. (topical review)

No abstract available

[en] P-glycoprotein (Pgp) and multidrug resistance-associated protein (MRP) expressions as well as Tc-99m methoxisobutylisonitrile (MIBI) images were assessed in 25 patients hepatocellular carcinoma (HCC). Tc-99m MIBI imaging was performed 10 minutes after intravenous injection of 20 mCi Tc-99m MIBI. Using immunohistochemical staining, 60% of the HCC lesions showed positive for Pgp and 64% showed positive for MRP. In 3 patients with MIBI uptake, immunohistochemical study of tumor tissue showed no Pgp stained cells. Nevertheless, they were all positive for MRP. The result of Tc-99m MIBI imaging is more related to the expression of Pgp than MRP gene. It is possible that other membrane transporters as well as Pgp and MRP are involved in the efflux of Tc-99m MIBI

[en] Full text: The gyrokinetic neoclassical particle-in-cell code XGCa coupled to the MHD code M3D-C1 is applied to study the particle and heat flux caused by external 3D magnetic perturbations in a DIII-D H-mode plasma. Despite the existence of KAM surfaces in the pedestal, our simulations, which so far are limited to the 0.5 to 1 ms directly after the RMP field is switched on, show the beginning of density pump-out at the pedestal top as well as a steepening and narrowing electron temperature pedestal around the separatrix similar to observations in the DIII-D tokamak. The RMP field is known to enhance particle transport leading to density pump-out and to be able to suppress edge localized modes (ELMs) in tokamak plasma. Pump-out occurs with or without ELM suppression, and understanding its physics basis is important for developing predictive understanding. Due to the short time scales studied so far with XGCa, core heat and torque sources, and turbulent transport can be neglected. Only an electron heat sink on the separatrix and in the scrape-off layer is added to model radiative cooling. The increased, RMP induced particle and energy fluxes observed in our study — despite the presence of KAM surfaces in the M3D-C1 computed screened RMP field — are mostly of convective nature as can be seen from the weak change in the electron temperature compared to the particle density at the pedestal top. While these XGCa simulations already reproduce essential experimental findings such as the beginning density pump-out and the convective nature of the RMP induced energy flux, several enhancements are being investigated. Those enhancements include initializing the simulation with experimental toroidal rotation profiles, adding NBI torque source, replacing the simple SOL heat sink by an actual model for impurity radiation, and adding a turbulent transport model, and core heat and torque sources. Self-consistent, kinetic calculation of the screened RMP field with an XGCa-internal solver for Ampére’s law and comparison to the M3D-C1 screened RMP field is investigated as well. Supported by the U.S. Department of Energy via contracts DE-AC02-09CH11466, DE-FC02-04ER54698. Computing time provided by ALCF (DE-AC02-06CH11357) and NERSC (DEAC02-05CH11231) through ALCC, INCITE, and ERCAP. (author)

[en] We investigated flow characteristics in a hydraulic coupling at different charged water conditions and speed ratios. Hence, simulations were performed for three-dimensional two-phase flow by using the VOF method. The realizable k-ε turbulence model was adopted. To resolve the interaction of passing blades of the primary and secondary wheels, simulations were conducted in the unsteady framework using a sliding grid technique. The results show that the water-air distribution inside the wheel is strongly dependent upon both amount of charged water and speed ratio. Generally, air is accumulated in the center of the wheel, forming a toroidal shape wrapped by the circulating water. The results also show that at high speed ratios, the solid-body-like rotation causes dry areas on the periphery of the wheels and, hence, considerably decreases the circulating flow rate and the transmitted torque. Furthermore, the momentum transfer was investigated through the concept of a mass flux triangle based on the local velocity multiplied by the local mixture density instead of the velocity triangle commonly used in a single-phase turbomachine analysis. Also, the mass fluxes along the radius of the coupling in the partially charged and fully charged cases were found to be completely different. It is shown that the flow rate at the interfacial plane and also the transmitted torque are closely related and are strongly dependent upon both the amount of charged water and speed ratio. Finally, a conceptual categorization together with two comprehensive maps was provided for the torque transmission and also circulating flow rates. These two maps in turn exhibit valuable engineering information and can serve as bases for an optimal design of a hydraulic coupling.