No abstract

As the power available in the initial phase of the ITER operation will be limited, accessing the high confinement mode (H-mode) with low heating power will be a critical issue. In the recent experiment on EAST, the H-mode was obtained for the first time with lower hybrid current drive (LHCD) wave only. Reciprocating Langmuir probe measurements at the outer midplane showed that the electron density ne and electron temperature Te in the scrape-off layer (SOL) were significantly reduced in the ELM-free phase, resulting in the increase of lower-hybrid wave (LHW) reflection. It was found that the power loss P loss was comparable during the L-H transition, by comparing the adjacent L-mode and H-mode discharge. The Dα emission, Te and ne decreased rapidly in the time scale of about 1 ms, and the radial electric field Er turned positive in this process near the last closed flux surface. Multiple L-H-L transitions were observed during a single shot when the applied LHW power was marginal to the threshold. The floating potential (V f) had negative spikes corresponding with the Dα signal, and Er oscillation evolved into several intermittent negative spikes just before the L-H transition. In some shots, dithering was observed just before the L-H transition.

New perylenebisimide derivatives hydroxyperylenebisimide and naphthoperylenebisimide were obtained and applied to construct a new solvatochromic dyad 9. The solvatochromic behavior of hydroxyperylenebisimide was studied, and the structure of naphthoperylenebisimide was determined by X-ray crystallography. The spectral studies indicated that the hydroxyperylenebisimide and naphthoperylenebisimide units of dyad 9 were strongly coupled in the ground state, and as a result the fluorescence of the naphthoperylenebisimide unit was almost quenched and that of the hydroxyperylenebisimide unit was greatly enhanced due to the fluorescence resonance energy transfer (FRET). As we expected, this FRET process could be tuned with the addition of protons, base, and ferric ions. This behavior of dyad 9 could be interpreted by a two-input INH logic gate, while in the presence of Fe(III), the ion complex of 9 could execute a two-input XOR logic gate. By changing the output signal, a combinational logic circuit with three inputs could also be interpreted.

The first high harmonic spectrum containing only the odd orders was observed in experiments 30 years ago. However, a spectrum containing pure even harmonics has never been observed. We investigate the generation of pure even harmonics from oriented CO molecules in linearly polarized laser fields employing the time-dependent density-functional theory. We find that the even harmonics, with no odd orders, are generated with the polarization perpendicular to the laser polarization when the molecular axis of CO is perpendicular to the laser polarization. The generation of pure even harmonics reveals a type of dipole acceleration originating from the permanent dipole moment. This phenomenon exists in all systems with permanent dipole moments, including bulk crystal and polyatomic molecules.

To study bistatic scattering from a target at low altitude above twodimensional (2D) randomly rough sea surface under an electromagnetic (EM) wave incidence at low grazing angle (LGA), a numerical approach of the finite element method (FEM) is developed. The conformal perfectly matched layer (PML), as the truncation boundary of the FEM, is employed to reduce the reflection error of planar PML in conventional FEM. Numerical code of our FEM is examined by available solution of the forward backward iterative (FBM) method. Bistatic and back-scattering from composite model of a target above random rough sea surface generated by Monte Carlo realization, and functional dependence upon the sea surface wind speed, target altitude, incident and scattering angles, etc. are numerically simulated and discussed. This paper presents a numerical description of the observation principle and physical insight associated with the coupling interactions of a complex volumetric target and random rough sea surface.A study of scattering from a volumetric target above random rough surface is of great significance in target detection in terrain and oceanic clutters. Most of analytical approaches to rough surface scattering are based on some approximations, such as the Kirchhoff tangent plane approximation, small perturbation approximation, two-scale model and others [1] . Analytical study of scattering from an object above the surface has been limited to the model of a sphere or a cylinder above a planar conducting surface [2,3] . Numerical model for simulation of scattering from complex target and rough surface should have the aid of computational methods of electromagnetics, e.g. integral equation method [4] , finite element method [5] , finite difference time domain method (FDTD), as well as widely discussed forward backward method(FBM) [6ü8] .

Wavelength division multiplexing technology, adopted to increase the information density, plays a significant role in optical communication. However, in acoustics, a similar function can be hardly implemented due to the weak dispersion in natural acoustic materials. Here, an acoustic demultiplexer, based on the concept of metasurfaces, is proposed for splitting acoustic waves and propagating along different trajectories in a low frequency range. An acoustic metasurface, containing multiple resonant units, is designed with various phase profiles for different frequencies. Originating from the highly dispersive properties, the resonant units are independent and merely work in the vicinity of their resonant frequencies. Therefore, by combing multiple resonant units appropriately, the phenomena of anomalous reflection, acoustic focusing, and acoustic wave bending can occur in different frequencies. The proposed acoustic demultiplexer has advantages on the subwavelength scale and the versatility in wave control, providing a strategy for separating acoustic waves with different Fourier components.

No abstract

The ionization rate of molecules in intense laser fields may be much lower than that of atoms with similar binding energy. This phenomenon is termed the ionization suppression of molecules and is caused by the molecular inner structure. In this paper, we perform a comprehensive study of the ionization suppression of homonuclear diatomic molecules in intense laser fields of linear and circular polarizations. We find that for linear polarization the total ionization rate and the ionization suppression depend greatly on the molecular alignment, and that for circular polarization the ionization suppression of molecules in the antibonding ͑bond-ing͒ shells disappears ͑appears͒ for laser intensities around 10 15 W / cm 2 . We also find that the molecular photoelectron energy spectra are greatly changed by the interference effect, even though the total ionization rate of molecules remains almost the same as that of their companion atoms.