We study heat transport in magnetic island in Tokamak. As electron cyclotron resonance heating (ECRH) has good locality it is used to simulate ECRH plasmas for local Gaussian heat source in magnetic island. In the case of simultaneous existence of background heat source and local Gaussian heat source, variation of radial electron temperature distribution and heat transport in local Gaussian heat source are studied. Analysis is made on influence of local Gaussian heat source on temperature perturbation and magnetic island constraint energy.

With pseudo-potential plane-wave based on density functional theory (DFT), effects of zinc vacancies on ZnO lattice parameters and electronic structure of Al-P co-doped were studied. Formation energy, density of states are analysed. It shows that Al_Zn-P_Zn has the lowest formation energy and presents n-type in the process of co-doping. Presence of zinc vacancies make cell volume decrease, and lattice constant c increase and decreases as concentration of zinc vacancies increase. According to formation energy of co-doping, formation of zinc vacancies system is more stable than Al_Zn-P_O. System with Al and P ratio of 1:2 co-doping can reduce formation energy and become more stable. With comparisons of band structure of V_Zn and 2V_Zn, it is found that band gap increased with zinc vacancies increasing, which makes p-type ZnO more obvious and enhances conductivity of Al_Zn-2P_Zn co-doping systems. However, for Al_Zn-2P_Zn co-doping of 2V_Zn, it shows great superiority of p-type. According to state density analysis, Al_Zn-2P_Zn of 2V_Zn makes the state density more diffuse, and go through the Fermi level, which leads to formation of obvious p-type. As a result, better p-type ZnO can be obtained by controlling Al/P in proportion of 1:2 co-doing with zinc vacancy to 2V_Zn.

With plane-wave pseudo-potential method of first-principles,effect of dopant Fe on dehydrogenation characteristics of LiAlH₄ and mechanism were studied.Dopant formation energy,electronic density of states and dissociation energy of H were investigated.Bonding state and structure-stability of the crystal were analyzed.It indicates that as Fe occupied an interstitial site,an Al site or an Li site,dehydrogenation properties of LiAlH₄ were improved.Fe tended to occupy the interstitial site.Analysis on electronic structure reveals that there exist strong interactions between a dopant Fe and its nearest neighbouring Al atoms as Fe occupied an interstitial site.Meanwhile,interaction between a dopant Fe and its nearest neighbouring H atoms is also considerably strong.Stability of the [AIH₄] ligand is distorted.Therefore,dehydrogenation properties of LiAlH₄ are improved.In general,dopant Fe improve dehydrogenation properties of LiAlH₄,which is consistent with experimental observations.

A one-dimensional fluid model for RF methane plasma is presented.Equations of particle balance with drift-diffusion approximation for fluxes,and electron energy balance are solved.Totally 20 species(neutrals,radicals,ions,and electrons) are included in the model,as well as 49 reactions(27 electron reactions,7 ion-neutral reactions,and 15 neutral-neutral reactions).It is found that high electron reaction-rate occurs at high electric-field region.Besides inlet gas CH₄,neutral gases H₂,C₂H₆,C₃H₈,C₂H₄,and C₂H₂ also show high densities in the plasma.The main radical in plasma is CH₃,with a density of about 10¹⁹m^-3.At low pressures(e.g.,18Pa) the most important ion is CH₅⁺.At high pressures(e.g.,67Pa) C₂H₅⁺ becomes the dominant ion.Radical and ion fluxes towards electrode(except C₂H₅⁺) increase slightly with power.

Electron energy distribution function(EEDF) in RF methane plasma is calculated with Boltzmann equation and Lorentz approximation. Instead of a self-consistent RF field satisfying Poisson's equation,a simple electric field distribution is used.6 neutrals are included,as well as 27 electron-neutral reactions.EEDF yields information about electron reaction rates in plasma,electron average energy,and transport coefficients.In the sheath region,EEDF is Maxwellian,and in the bulk region a Druyvesteyn EEDF is found.An electron average energy peak occurs in the sheath region,together with electron reaction rates.Differing from constant transport coefficients used in references,electron diffusion and mobility coefficients strongly depend on RF period and space.

The mesoscopic transport through a quantum dot and a toroidal carbon nanotube (TCN) coupled system is investigated with the nonequilibrium Green's function technique.The coherent tunneling is strongly related to the energy structures of the TCN and the quantum dot.The Aharonov-Bohm effect causes energy levels of the TCN to change periodically,and the tunneling current oscillates with the magnetic flux.The detailed nanostructure of TCN exhibits metal-semiconductor transition,and this behavior is reflected in the output current.The matching-mismatching of quantum levels of the sub-systems plays important role in the mesoscopic transport.

A large-diameter coaxial relativistic backward-wave oscillator is presented. The linearized Lorentz force equation, continuity equation, and Maxwell equations are used to calculate the system dispersion relations for a backward-wave oscillator with a dual-plate rippled-wall waveguide. The system also includes an infinitely thin relativistic electron beam propagating between the opposing plates. Using this theory, the influences of various system parameters on the beam-wave interaction, especially on the exponential growth rate of the wave, are discussed in detail. This theory is also used to design a large-diameter coaxial relativistic backward-wave oscillator in 3cm waveband.

Quantum coherent transport through a superconductor-quantum-dot coupled system is investigated mainly for considering the current characteristics under the interactions of microwave field and Zeeman field. The mean field BCS theory and non-equilibrium Green function technique are employed to solve the tunneling problem. The Bogoliubov transformation is employed to derive the current formula, and the current-voltage, current-magnetic field and Josephson current curves are given by numerical calculations.