- Home

[hal-02071160] Development of a compact bushing for NBI (12/04/2019)

Research into a novel type of compact bushing is being conducted through the HVIV (High Voltage holding In Vacuum) partnership between CEA-Cadarache 1 , GeePs-Centralesupélec 4 , LPGP 3 and LCAR 2. The bushing aims to concentrate the high electric field inside its interior, rather than in the vacuum tank. Hence the field emission current is also concentrated inside the bushing and it can be attempted to suppress this so-called dark current by conditioning the internal surfaces and by adding gas. LCAR have performed theoretical quantum mechanical studies of electron field emission and the role of adsorbates in changing the work function. LPGP studied the ionization of gas due to field emission current and the behavior of micro particles exposed to emissive electron current in the vacuum gap under high electric fields. Experiments at Geeps have clarified the role of surface conditioning in reducing the dark current. Geeps also found that adding low pressure nitrogen gas to the vacuum is much more effective than helium in reducing the field emission. An interesting observation is the growth of carbon structures after exposure of an electrode to the electric field. Finally, IRFM have performed experiments on a single stage test bushing that features a 36 cm high porcelain insulator and two cylindrical electrode surfaces in vacuum or low-pressure gas. Using 0.1 Pa N 2 gas, the voltage holding exceeded 185 kV over a 40 mm "vacuum" gap without dark current. Above this voltage, exterior breakdowns occurred over the insulator, which was in air. The project will finish with the fabrication of a 2-stage compact bushing, capable to withstand 400 kV.

[hal-02065304] 4s to 5s and 4p photoexcitation dynamics of K atoms from the surface of helium nanodroplets: a theoretical study (12/04/2019)

[...]

[hal-02024345] Spontaneous emission of a sodium Rydberg atom close to an optical nanofibre (12/04/2019)

[...]

[hal-01982362] A three dimensional numerical quantum mechanical model of electronic field emission from metallic surfaces with nanoscale corrugation (12/04/2019)

The effects on the electronic emission of the presence of nanoscale steps on a tungsten surface are investigated for the first time using three dimensional quantum mechanical models. The plane wave periodic version of the density functional theory is used to obtain the electronic wavefunctions and potentials for flat and corrugated structures. Local and averaged emitted current densities are obtained from them using time dependent perturbation theory. The orders of magnitude of the averaged current densities resulting from these calculations are similar for both flat and corrugated cases, however, strong enhancements are observed on the local current densities near the edges of the steps. These numerical results are compared with those of the analytical Fowler-Nordheim type models. The slopes of the Fowler-Nordheim plots are in good agreement for both numerical and analytical models, but the magnitudes of the emitted currents are significantly different. This is related to weaknesses in the description of the electronic structure of the metal in the analytical models.

[hal-01965494] Contribution of the density-functional-based tight binding scheme to the description of water clusters: methods, applications and extension to bulk systems (12/04/2019)

[...]

[hal-01951617] Self-bound ultradilute Bose mixtures within local density approximation (12/04/2019)

[...]

[hal-01877234] Calculations with experimental validations of cross-sections and transport coefficients of Xe+ colliding with Xe (12/04/2019)

[...]

[hal-01834073] Quantum and semi-classical collision cross-sections and transport data for a Kr+/Kr system (12/04/2019)

[...]

[hal-01825664] Coherent quantum dynamics launched by incoherent relaxation in a quantum circuit simulator of a light-harvesting complex (12/04/2019)

[...]

[hal-01793017] Non-Markovianity in the optimal control of an open quantum system described by hierarchical equations of motion (12/04/2019)

[...]

[hal-01787210] Helium-induced electronic transitions in photo-excited BA+ –HEn exciplexes (12/04/2019)

[...]

ELECTRONIC BUBBLE FORMATION CONICAL INTERSECTION ELECTRON-NUCLEAR DYNAMICS Fast light Cope rearrangement Classical trajectory Calcium Flux operator ENERGY Coulomb presssure Muonic hydrogen FIELD CLASSICAL TRAJECTORY METHOD Half revival Extra dimension Ultrashort pulses Anharmonicity CAVITY Cluster Coordonnées hypersphériques elliptiques Alkali-halide DEPENDENT SCHRODINGER-EQUATION ENTANGLEMENT DRIVEN Bohmian trajectories COLLISION ENERGY Agrégats Slow light Atomic clusters Density functional theory Effets de propagation COHERENT CONTROL Effets isotopiques Dynamics Transport électronique Electronic transport inelastic effects Electron transfer Ab-initio HEME POCKET Théorie de la fonctionnelle de la densité Non-equilibrium Green's function DYNAMICS Wave packet interferences Theory DENSITY Diels-Alder reaction Collisions ultra froides MCTDH Tetrathiafulvalene Propagation effects Femtochemistry Fonction de Green hors-équilibre CHEMICAL-REACTIONS Transitions non-adiabatiques Deformation HYDROGEN-BOND Excitation energy transfer EET Dynamique quantique Electron-surface collision Effets transitoires WAVE-PACKET DYNAMICS HCN ISOMERIZATION Cryptochrome Ground states STATE Dynamique mixte classique HYDROGEN-EXCHANGE REACTION Dark energy Fluorescence ALGORITHM ATOMS MODEL QUANTUM OPTIMAL-CONTROL DIFFERENTIAL CROSS-SECTIONS Coherent control Collision frequency Energy spectrum Gaussian wave packets Fluctuations Composés organiques à valence mixte FEMTOSECOND LASER-PULSE Quantum dynamics Dissipative dynamics Close-coupling Hetero junction Effets inélastiques Dissipative quantum methods Drops Clusters Contrôle cohérent DISSIPATION Ab initio calculations Dynamique moléculaire quantique COMPLEX ABSORBING POTENTIALS ENTROPY Casimir effect Electric field AR ELECTRON DYNAMICS Cosmological constant