Feng Q.,CAS Chengdu Institute of Optics and Electronics |
Feng Q.,Southwestern Institute of Physics |
Pu M.,CAS Chengdu Institute of Optics and Electronics |
Hu C.,CAS Chengdu Institute of Optics and Electronics |
Luo X.,CAS Chengdu Institute of Optics and Electronics
Optics Letters | Year: 2012
We propose a broadband infrared absorber by engineering the frequency dispersion of metamaterial surface (metasurface) to mimic an ideal absorbing sheet. With a thin layer of structured nichrome, a polarizationindependent absorber with absorption larger than 97% is numerically demonstrated over a larger than one octave bandwidth. It is shown that the bandwidth enhancement is related with the transformation of the Drude model of free electron gas in metal film to the Lorentz oscillator model of a bound electron in the structured metallic surface. We believe that the concept of dispersion engineering may provide helpful guidance for the design of a broadband absorber. © 2012 Optical Society of America.
Guo B.,Wuhan University of Technology |
Qiu X.-M.,Southwestern Institute of Physics
Journal of Electromagnetic Waves and Applications | Year: 2011
In the present paper, we first show that the plasma injected into the interaction region forms a periodical distribution of the plasma density that is called self-induced density grating and exerts a periodic perturbation on the dielectric constant under two strong counterpropagating waves modulation. In succession, we demonstrate that the self-induced quasi periodic plasma density grating formed by the self-induced distributed feedback possesses the properties of plasma photonic crystal (PPC). Therefore, the formation of PPC by the self-induced quasi periodic plasma density grating is a feasible fabrication scenario for PPC. Based on an equivalent model of the plasma density grating, a dispersion relation is derived, and a simple case is calculated and discussed. © 2011 VSP.
Hao G.Z.,Southwestern Institute of Physics |
Wang A.K.,Southwestern Institute of Physics |
Liu Y.Q.,EURATOM |
Qiu X.M.,Southwestern Institute of Physics
Physical Review Letters | Year: 2011
A stability analysis for the resistive wall mode is studied in the presence of trapped energetic particles (EPs). When the EPs' beta exceeds a critical value, a fishbonelike bursting mode (FLM) with an external kink eigenstructure can exist. This offers the first analytic interpretation of the experimental observations. The mode-particle resonances for the FLM and the q=1 fishbone occur in different regimes of the precession frequency of EPs. In certain ranges of the plasma rotation speed and the EPs' beta, a mode conversion can occur between the resistive wall mode and FLM. © 2011 American Physical Society.
Shi B.-R.,Southwestern Institute of Physics
Chinese Physics B | Year: 2014
An analytical expression of the peeling mode in the near separatrix region of diverted tokamak plasma is derived. It is shown that in diverted plasmas both with single and double X points, though the perturbed potential energy of the unstable peeling mode tends to be large, its growth rate becomes very small due to the even larger kinetic energy. Compared to some recent studies that give qualitatively correct results about this growth rate, our result is directly related with the diverted equilibrium quantities suitable for application to realistic experiments. © 2014 Chinese Physical Society and IOP Publishing Ltd.
Qu H.,Southwestern Institute of Physics
Plasma Science and Technology | Year: 2013
A simple and direct theoretical method has been proposed to investigate the so- called ion-banana-orbit-width (IBW) effect on the bootstrap current in the region of magnetic islands generated by the neoclassical tearing mode (NTM). The result shows that, when the IBW approaches the island width, the (ion) bootstrap current can be partly restored inside the island while the pressure profile is flattened. This can lead to the reduction of the bootstrap current drive on the NTM. The strength of the IBW effect on the NTM is related to the safety factor and the inverse aspect ratio on the rational surface.
Luo T.,Southwestern Institute of Physics
Journal of Nuclear Materials | Year: 2011
Li4SiO4 will be applied as tritium breeding materials in future fusion reactor. The release behavior of tritium from neutron-irradiated Li4SiO4 should be sensitive to the chemical states of lithium, oxygen and silicon on the surface of Li 4SiO4 with irradiated defects. The present study is focused on the influence of hydrogen isotopes and irradiation defects on surface chemical state of Li4SiO4. The X-ray Photoelectron Spectroscopy (XPS) was compared between non-irradiated Li4SiO 4 and D2 +-irradiated one. It was observed by that the binding energy (BE) of electron for Li-1s, O-1s and Si-2p of non-irradiated Li4SiO4 were 60.9 eV, 536.1 eV and 107.1 eV respectively. However new XPS peak for Li-1s at 57.2 eV, three XPS peaks for O-1s (at 536.1 eV, 533.2 eV and 531.3 eV, respectively) and three XPS peaks for Si-2p (at 107.1 eV, 104.2 eV and 99.7 eV, respectively) were observed in D 2 +-irradiated Li4SiO4. It is considered that the XPS peaks of 531.3 eV and 104.2 eV should be corresponding to O-1s and Si-2p in -Si-O-D while the XPS peak of 533.2 eV should be corresponding to O-1s in D-O-D. The formation of -Si-O-D and D-O-D is considered to be due to typical irradiated defects (lithium vacancy, silicon vacancy and implanted deuterium) induced by D2 +-irradiation. © 2010 Elsevier B.V. All rights reserved.
Shi B.,Southwestern Institute of Physics
Plasma Physics and Controlled Fusion | Year: 2010
The tokamak pedestal density structure is generally studied using a diffusiondominant model. Recent investigations (Stacey and Groebner 2009 Phys. Plasmas 16 102504) from first principle based physics have shown a plausible existence of large inward convection in the pedestal region. The diffusion- convection equation with rapidly varying convection and diffusion coefficients in the near edge region and model puffing-recycling neutral particles is studied in this paper. A peculiar property of its solution for the existence of the large convection case is that the pedestal width of the density profile, qualitatively different from the diffusion-dominant case, depends mainly on the width of the inward convection and only weakly on the neutral penetration length and its injection position. © 2010 IOP Publishing Ltd.
Liu Y.,Southwestern Institute of Physics |
An X.,Southwestern Institute of Physics |
Wang Q.,Southwestern Institute of Physics
Applied Optics | Year: 2013
An improved method of backward ray tracing is proposed according to the theory of geometrical optics and thermal radiation heat transfer. The accuracy is essentially raised comparing to the traditional backward ray tracing because ray orders and weight factors are taken into account and the process is designed as sequential and recurring steps to trace and calculate different order stray lights. Meanwhile, it needs very small computation comparing to forward ray tracing because irrelevant surfaces and rays are excluded from the tracing. The effectiveness was verified in the stray radiation analysis for a cryogenic infrared (IR) imaging system, as the results coincided with the actual stray radiation irradiance distributions in the real images. The computation amount was compared with that of forward ray tracing in the narcissus calculation for another cryogenic IR imaging system, it was found that to produce the same accuracy result, the computation of the improved backward ray tracing is far smaller than that of forward ray tracing by at least 2 orders of magnitude. © 2013 Optical Society of America.
Shi B.,Southwestern Institute of Physics
Nuclear Fusion | Year: 2011
Generalized Grad-Shafranov equation for tokamak equilibrium with incompressible toroidal and poloidal flows is solved to obtain a double-null diverted configuration based on an approach presented before (Shi 2008 Plasma Phys. Control. Fusion 50 085006). This solution consists of only two terms of base functions obtained from the variable-separating method and suitable for describing both the internal region within the separatrix and a scrape-off layer region. Dependences of the main equilibrium properties, such as the magnetic field, plasma pressure and the equilibrium radial electric field and the plasma current on flows are revealed. In particular, we find that the presence of poloidal flow causes a deviation of the current surface from the magnetic surface and the sheared poloidal flow produces a non-zero toroidal current component that possibly affects the peeling-ballooning stability of the pedestal. © 2011 IAEA.
Southwestern Institute of Physics | Date: 2013-12-30
This device includes a molecular beam valve, a cold/hot precipitator and a magnetic shielding cylinder, wherein molecular beam valve is nested in cold/hot precipitator and precipitator is nested in magnetic shielding cylinder and molecular beam valve is fixed on flange connected to vacuum chamber of a fusion device, outlet of molecular beam valve has a lengthened Laval nozzle. The device solves technical problem that plasma feeding efficiency of existing supersonic gas injector is below 20% during operation of a high-performance Tokamak high confinement mode and constraint is poor; and an effect of applying device to existing large-scale superconducting Tokamak has shown: feeding efficiency reaches 40%; and a function of triggering a low constraint mode converted to a high constraint mode; and a function of mitigating instability of an edge localized mode, so heating load on wall surfaces of fusion device is reduced by 50%, thereby maintaining normal H-mode operation.