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<jats:p>Assume that a fluid is inviscid, incompressible, and irrotational. A nonlinear Schrödinger equation (NLSE) describing the evolution of gravity waves in finite water depth is derived using the multiple-scale analysis method. The gravity waves are influenced by a linear shear flow, which is composed of a uniform flow and a shear flow with constant vorticity. The modulational instability (MI) of the NLSE is analyzed, and the region of the MI for gravity waves (the necessary condition for existence of freak waves) is identified. In this work, the uniform background flows along or against wave propagation are referred to as down-flow and up-flow, respectively. Uniform up-flow enhances the MI, whereas uniform down-flow reduces it. Positive vorticity enhances the MI, while negative vorticity reduces it. Hence, the influence of positive (negative) vorticity on MI can be balanced out by that of uniform down (up) flow. Furthermore, the Peregrine breather solution of the NLSE is applied to freak waves. Uniform up-flow increases the steepness of the free surface elevation, while uniform down-flow decreases it. Positive vorticity increases the steepness of the free surface elevation, whereas negative vorticity decreases it.</jats:p>

<jats:p>During edge localized modes (ELMs), the sheath evolution in front of the Experimental Advanced Superconducting Tokamak (EAST) upper divertor is studied to estimate the sputtered tungsten (W) atoms from the divertor target. A large potential drop across the sheath is formed during ELMs by compared with inter-ELMs, and the maximum of sheath potential drop can exceed one thousand of eV in current EAST operation. Due to the enhancement of the sheath potential drop during ELMs, the W physical sputtering yield from the deuterium (D) ions and the impurity ions on the upper divertor target is found to be significant. It is established that the sputtered W yield during ELMs is at least higher by an order of magnitude than inter-ELMs, and D ions and carbon (C) ions are the main ions governing the W production for the current H-mode with ELMs discharges. With increase in the pedestal electron temperature, the maximum of the D and C ion impact energy during ELMs shows a nearly linear increase, and the D ions have sufficient impact energy to cause the strong W physical sputtering. As a consequence, the D ions may dominate the sputtered W flux from the divertor target when the C concentration is controlled less than one percent for the higher heating power H-mode with ELM discharges in near future.</jats:p>

<jats:p>Based on neon gas puffing, an active feedback control of H-mod plasma divertor detachment experiment was successfully operated on the EAST tokamak. During the feedback control discharge, the plasma was detached by puffing neon gas and the strike point splitting phenomenon on divertor target was also clearly observed by divertor probes diagnostic. In boundary region, many neutral particle processes (atom and molecule) were happened and accompanied by their emission spectra under the detachment discharge. By studying these emission spectra, it is helpful for us to understand the role of atoms and molecules in boundary recycling, which is important for studying the physical mechanism of divertor detachment. For the Fulcher-<jats:italic>α</jats:italic> system (<jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{d}}(3{\rm{p}})}^{3}{\Pi }_{{\rm{u}}}^{\pm }\to {{\rm{a}}(2{\rm{s}})}^{3}{\Sigma }_{{\rm{g}}}^{+})$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">d</mml:mi> <mml:mo>(</mml:mo> <mml:mn>3</mml:mn> <mml:mi mathvariant="normal">p</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> </mml:msup> <mml:msubsup> <mml:mo>Π</mml:mo> <mml:mi mathvariant="normal">u</mml:mi> <mml:mo>±</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">a</mml:mi> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mi mathvariant="normal">s</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> </mml:msup> <mml:msubsup> <mml:mo>Σ</mml:mo> <mml:mi mathvariant="normal">g</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_12_125202_ieqn1.gif" xlink:type="simple" /> </jats:inline-formula>, D<jats:sub>2</jats:sub> emission spectra in the range from 601 nm to 606 nm were observed, identified and fitted in the detachment experiment for the first time on the EAST, and the spectra in the <jats:italic>Q</jats:italic>(0–0) band (<jats:inline-formula> <jats:tex-math><?CDATA ${{\rm{d}}}^{3}{\Pi }_{{\rm{u}}}^{-}\to {{\rm{a}}(2{\rm{s}})}^{3}{\Sigma }_{{\rm{g}}}^{+})$?></jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mi mathvariant="normal">d</mml:mi> <mml:mn>3</mml:mn> </mml:msup> <mml:msubsup> <mml:mo>Π</mml:mo> <mml:mi mathvariant="normal">u</mml:mi> <mml:mo>−</mml:mo> </mml:msubsup> <mml:mo>→</mml:mo> <mml:msup> <mml:mrow> <mml:mi mathvariant="normal">a</mml:mi> <mml:mo>(</mml:mo> <mml:mn>2</mml:mn> <mml:mi mathvariant="normal">s</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mn>3</mml:mn> </mml:msup> <mml:msubsup> <mml:mo>Σ</mml:mo> <mml:mi mathvariant="normal">g</mml:mi> <mml:mo>+</mml:mo> </mml:msubsup> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="cpb_28_12_125202_ieqn2.gif" xlink:type="simple" /> </jats:inline-formula> in the <jats:italic>Q</jats:italic> branch of the Fulcher-<jats:italic>α</jats:italic> system were used for detailed analysis to acquire the boundary region temperature <jats:italic>T</jats:italic> <jats:sub>e</jats:sub> (below 5 eV), which could not be provided very well by other diagnostics on the EAST. An electronic version deuterium molecular spectral line database was established to identify the spectral lines and a multi-peak fitting program was developed to fit and analyze the observed spectra.</jats:p>

<jats:p>Nonlinear interaction between tearing modes (TM) and slab ion-temperature-gradient (ITG) modes is numerically investigated by using a Landau fluid model. It is observed that the energy spectra with respect to wavenumbers become broader during the transition phase from the ITG-dominated stage to TM-dominated stage. Accompanied with the fast growth of the magnetic island, the frequency of TM/ITG with long/short wavelength fluctuations in the electron/ion diamagnetic direction decreases/increases respectively. The decrease of TM frequency is identified to result from the effect of the profile flattening in the vicinity of the magnetic island, while the increase of the frequencies of ITG fluctuations is due to the eigenmode transition of ITG induced by the large scale zonal flow and zonal current related to TM. Roles of zonal current induced by the ITG fluctuations in the instability of TM are also analyzed. Finally, the electromagnetic transport features in the vicinity of the magnetic island are discussed.</jats:p>

<jats:p>Plasma equilibrium parameters such as position, X-point, internal inductance, and poloidal beta are essential information for efficient and safe operation of tokamak. In this work, the artificial neural network is used to establish a non-linear relationship between the measured diagnostic signals and selected equilibrium parameters. The estimation process is split into a preliminary classification of the kind of equilibrium (limiter or divertor) and subsequent inference of the equilibrium parameters. The training and testing datasets are generated by the tokamak simulation code (TSC), which has been benchmarked with the EAST experimental data. The noise immunity of the inference model is tested. Adding noise to model inputs during training process is proved to have a certain ability for maintaining performance.</jats:p>

<jats:p>To obtain large-volume non-thermal arc plasma (NTAP), a multiple NTAP generator with three pairs of electrodes has been developed. The arc plasma characteristics, including dynamic process, spatial distribution, and rotation velocity in the discharge zone, were investigated by high speed photograph and image processing methods. The results showed that the dynamic behaviors and spatial distribution of the arc plasma were strongly related to the electrode configuration. A swirl flow of multi-arc plasma was formed by adjusting the electrode configuration, and a steady luminance area was clearly observed in the center of the discharge zone. Moreover, the size of the luminance area increased by decreasing the gas flow rate. The electrical connection in series could be formed between/among these arc columns with their respective driving power supplies in the multi-arc dynamic evolution process. An approximately periodical process of acceleration and deceleration of the arc rotation velocity was observed in the multi-arc generator with swirl flow configuration. In general, the mean velocity of arc rotation was higher in the multi-arc generator with swirl flow configuration when a pair of electrodes driven by a power supply were opposite to each other rather than adjacent.</jats:p>

<jats:p>Control over the tunneling current in spintronic devices by electrical methods is an interesting topic, which is experiencing a burst of activity. In this paper, we theoretically investigate the transport property of electrons in a spin-diode structure consisting of a single quantum dot (QD) weakly coupled to one nonmagnetic (NM) and one half-metallic ferromagnet (HFM) leads, in which the QD has an artificial atomic nature. By modulating the gate voltage applied on the dot, we observe a pronounced decrease in the current for one bias direction. We show that this rectification is spin-dependent, which stems from the interplay between the spin accumulation and the Coulomb blockade on the quantum dot. The degree of such spin diode behavior is fully and precisely tunable using the gate and bias voltages. The present device can be realized within current technologies and has potential application in molecular spintronics and quantum information processing.</jats:p>

<jats:p>The electronic Fabry–Pérot interferometer operating in the quantum Hall regime may be a promising tool for probing edge state interferences and studying the non-Abelian statistics of fractionally charged quasiparticles. Here we report on realizing a quantum Hall Fabry–Pérot interferometer based on monolayer graphene. We observe resistance oscillations as a function of perpendicular magnetic field and gate voltage both on the electron and hole sides. Their Coulomb-dominated origin is revealed by the positive (negative) slope of the constant phase lines in the plane of magnetic field and gate voltage on the electron (hole) side. Our work demonstrates that the graphene interferometer is feasible and paves the way for the studies of edge state interferences since high-Landau-level and even denominator fractional quantum Hall states have been found in graphene.</jats:p>

<jats:p>The optical-induced dielectric tunability properties of DAST crystal in THz range were experimentally demonstrated. The DAST crystal was grown by the spontaneous nucleation method (SNM) and characterized by infrared spectrum. With the optimum wavelength of the exciting optical field, the transmission spectra of the DAST crystal excited by 532 nm laser under different power were measured by terahertz time-domain spectroscopy (THz-TDS) at room temperature. The transmitted THz intensity reduction of 26 % was obtained at 0.68 THz when the optical field was up to 80 mW. Meanwhile, the variation of refractive index showed an approximate quadratic behavior with the exciting optical field, which was related to the internal space charge field of photorefractive phenomenon in the DAST crystal caused by the photogenerated carrier. A significant enhancement of 13.7 % for THz absorption coefficient occurred at 0.68 THz due to the photogenerated carrier absorption effect in the DAST crystal.</jats:p>

<jats:p>NH<jats:sub>3</jats:sub>-plasma treatment is used to improve the quality of the gate dielectric and interface. Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> is adopted as a buffer layer between HfO<jats:sub>2</jats:sub> and MoS<jats:sub>2</jats:sub> to decrease the interface-state density. Four groups of MOS capacitors and back-gate transistors with different gate dielectrics are fabricated and their <jats:italic>C</jats:italic>–<jats:italic>V</jats:italic> and <jats:italic>I</jats:italic>–<jats:italic>V</jats:italic> characteristics are compared. It is found that the Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub>/HfO<jats:sub>2</jats:sub> back-gate transistor with NH<jats:sub>3</jats:sub>-plasma treatment shows the best electrical performance: high on–off current ratio of 1.53 × 10<jats:sup>7</jats:sup>, higher field-effect mobility of 26.51 cm<jats:sup>2</jats:sup>/V·s, and lower subthreshold swing of 145 mV/dec. These are attributed to the improvements of the gate dielectric and interface qualities by the NH<jats:sub>3</jats:sub>-plasma treatment and the addition of Al<jats:sub>2</jats:sub>O<jats:sub>3</jats:sub> as a buffer layer.</jats:p>