Understanding impurity and bulk plasma transport in the scrape-off layer (SOL) of tokamak plasmas is critical for the design of future reactors. The development of a system on Alcator C-Mod for inferring impurity transport behaviour parallel and perpendicular to local magnetic field lines from impurity emission patterns (“plumes”) generated by local gas injection will be presented. Gas is injec...

Light emitting diodes (LEDs) are widely used nowadays. They are used in major parts of our life. But it is still necessary to improve their characteristics. In this paper the impurity and Indium atoms influence on the LEDs characteristics is investigated by computer simulation. Simulation was carried out in Sim Windows. The program was improved for this purpose by creating new files for AlGaInN...

We examine the dynamics of a bright solitary wave in the presence of a repulsive or attractive localized “impurity” in Bose-Einstein condensates (BECs). We study the generation and stability of a pair of steady states in the vicinity of the impurity as the impurity strength is varied. These two new steady states, one stable and one unstable, disappear through a saddle-node bifurcation as the st...

We examine the dynamics of a bright solitary wave in the presence of a repulsive or attractive localized “impurity” in Bose– Einstein condensates (BECs). We study the generation and stability of a pair of steady states in the vicinity of the impurity as the impurity strength is varied. These two new steady states, one stable and one unstable, disappear through a saddle-node bifurcation as the s...

We perform self-consistent studies of two-dimensional (2D) s-wave topological superconductivity (TSC) with Rashba spin-orbit coupling and Zeeman field by solving the Bogoliubov-de Gennes equations. In particular, we examine the effects of a nonmagnetic impurity in detail and show that the nature of the spin-polarised midgap bound state varies significantly depending on the material parameters. ...

Glossary Quantum dot device: nanoscopic electronic device resembling a transistor which incorporates a quantum dot as the central active element; sometimes also called single electron transistor. A quantum dot is an extremely small puddle of electrons which can be considered as an artificial atom since the confinement of electrons leads to quantized energy levels: the electrons form orbitals mu...

A one-dimensional tight-binding Hamiltonian describes the evolution of a single impurity interacting locally with N electrons. The impurity spectral function has a power-law singularity A(ω) ∝| ω− ω0 |−1+β with the same exponent β that characterizes the logarithmic decay of the quasiparticle weight Z with the number of electrons N , Z ∝ N−β. The exponent β is computed by (1) perturbation theory...

We demonstrate that a quantum spin Hall current, spontaneously generated at the edge of a two-dimensional topological insulator, acts as a source of spin pumping for a magnetic impurity with uniaxial anisotropy. One can then manipulate the impurity spin direction by means of an electrical current without using either magnetic electrodes or an external magnetic field. Furthermore we show that th...

We propose a fast impurity solver for the general quantum impurity model based on the perturbation theory around the atomic limit, which can be used in combination with the local density approximation LDA and the dynamical mean-field theory DMFT . We benchmark the solver in the two-band Hubbard model within DMFT against quantum Monte Carlo QMC and numerical renormalization-group NRG results. We...

We study theoretically the effects of diffusion, convection, and sawteeth on impurity profile evolution in tokamaks. Sawtooth effects are modeled after our' experimental observations that internal disruptions flatten radial profiles of impurity densities in the Alcator-C plasma core. We present numerical simulations and analytic results for confinement times and profile shapes, and we predict t...