The statistical-mechanical entropy of the stationary axisymmetric Einstein-Maxwell dilaton-axion black hole is investigated by using the “brick wall” model in which the original Dirichlet condition is replaced by a ...The statistical-mechanical entropy of the stationary axisymmetric Einstein-Maxwell dilaton-axion black hole is investigated by using the “brick wall” model in which the original Dirichlet condition is replaced by a scattering ansatz for the field functions at the event horizon and regularized with the Pauli-Villars scheme. It is also shown, for the Kerr black hole, that the statistical-mechanical entropy obtained from our derivation coincides with the one-loop correction to its thermodynamical entropy obtained by the conical singularity method.展开更多
We investigate the angular distribution and average kinetic energy of ions produced during ultrafast laser ablation （ULA） of a copper target in high vacuum. Laser produced plasma （LPP） is induced by irradiating th...We investigate the angular distribution and average kinetic energy of ions produced during ultrafast laser ablation （ULA） of a copper target in high vacuum. Laser produced plasma （LPP） is induced by irradiating the target with Ti：Sapphire laser pulses of -50 fs and 800 nm at an angle of incidence of 45°. An ion probe is moved along a circular path around the ablation spot, thereby allowing characterization of the time-of-flight （TOF） of ions at different angles relative to the normal target. The angular distribution of the ion flux is well-described by an adiabatic and isentropic expansion model of a plume produced by solid-target laser ablation （LA）. The angular width of the ion flux becomes narrower with increasing laser fluence. Moreover, the ion average kinetic energy is forward-peaked and shows a stronger dependence on the laser pulse fluence than on the ion flux. Such results can be ascribed to space charge effects that occur during the early stages of LPP formation.展开更多
基金the National Natural Science Foundation of China under Grant No.19575018the Natural Science Foundation of Hu'nan Province.
文摘The statistical-mechanical entropy of the stationary axisymmetric Einstein-Maxwell dilaton-axion black hole is investigated by using the “brick wall” model in which the original Dirichlet condition is replaced by a scattering ansatz for the field functions at the event horizon and regularized with the Pauli-Villars scheme. It is also shown, for the Kerr black hole, that the statistical-mechanical entropy obtained from our derivation coincides with the one-loop correction to its thermodynamical entropy obtained by the conical singularity method.
基金supported by the China National Scholarship Fund,the Executive Programme Italy-China for the years 2010–2012(No.CN10M02)the National Natural Science Foundation of China(No.11104201)+1 种基金the Key Laboratory of Opto-electronic Information Technology,Ministry of Education(Tianjin University)Open Fundthe European Union Seventh Framework Programme(FP7/2007–2013)(No.264098-MAMA)
文摘We investigate the angular distribution and average kinetic energy of ions produced during ultrafast laser ablation （ULA） of a copper target in high vacuum. Laser produced plasma （LPP） is induced by irradiating the target with Ti：Sapphire laser pulses of -50 fs and 800 nm at an angle of incidence of 45°. An ion probe is moved along a circular path around the ablation spot, thereby allowing characterization of the time-of-flight （TOF） of ions at different angles relative to the normal target. The angular distribution of the ion flux is well-described by an adiabatic and isentropic expansion model of a plume produced by solid-target laser ablation （LA）. The angular width of the ion flux becomes narrower with increasing laser fluence. Moreover, the ion average kinetic energy is forward-peaked and shows a stronger dependence on the laser pulse fluence than on the ion flux. Such results can be ascribed to space charge effects that occur during the early stages of LPP formation.
