The Experts below are selected from a list of 13878 Experts worldwide ranked by ideXlab platform

G A Bird - One of the best experts on this subject based on the ideXlab platform.

  • the rate of energy transfer from Air as an initially stationary particle acquires brownian motion
    Nano Energy, 2015
    Co-Authors: G A Bird
    Abstract:

    Abstract Physical simulation methods are used to determine the average time that is required for the Molecules in standard Air to transfer sufficient energy to an initially stationary particle to bring it to equilibrium with the gas as a Brownian particle. Individual particle trajectories are subject to random fluctuations and the average relaxation times are determined as ensemble averages over thousands of trajectories. The average initial power input to the particle is given by the equilibrium energy divided by the relaxation time. The relaxation time is determined for both spherical and cylindrical particles which vary in mass, diameter and, in the case of the cylinder, aspect ratio. The particle mass is normalized by the mass of an average Air Molecule, the diameter through the Knudsen number (the mean free path divided by the diameter) and the aspect ratio is the cylinder length to diameter. The relaxation time is found to be directly proportional to the product of the mass ratio and the square of the Knudsen number and inversely proportional to the aspect ratio. Empirical relations are developed for the relaxation times in each case. Should a cylindrical particle be fixed to a surface, it becomes a cantilevered nanowire that, if piezotronic, is capable of extracting energy. The relevance of the second law to this process is discussed together with speculations about the possibility of energy harvesting from nanodevices in Air.

Jie Zhang - One of the best experts on this subject based on the ideXlab platform.

  • tightly focused femtosecond laser pulse in Air from filamentation to breakdown
    Optics Express, 2010
    Co-Authors: Xiaolong Liu, X Y Liu, F Liu, Jie Zhang
    Abstract:

    The propagation of tightly focused femtosecond laser pulse with numerical aperture of 0.12 in Air is investigated experimentally. The formation and evolution of the filament bunch are recorded by time-resolved shadowgraph with laser energy from 2.4 mJ to 47 mJ. The distribution of electron density in breakdown area is retrieved using Nomarski interferometer. It is found that intensity clamping during filamentation effect still play a role even under strong external focusing. The electron density in some interaction zones is higher than 3×1019 cm-3, which indicates that each Air Molecule there is ionized.

Xiaolong Liu - One of the best experts on this subject based on the ideXlab platform.

  • tightly focused femtosecond laser pulse in Air from filamentation to breakdown
    Optics Express, 2010
    Co-Authors: Xiaolong Liu, X Y Liu, F Liu, Jie Zhang
    Abstract:

    The propagation of tightly focused femtosecond laser pulse with numerical aperture of 0.12 in Air is investigated experimentally. The formation and evolution of the filament bunch are recorded by time-resolved shadowgraph with laser energy from 2.4 mJ to 47 mJ. The distribution of electron density in breakdown area is retrieved using Nomarski interferometer. It is found that intensity clamping during filamentation effect still play a role even under strong external focusing. The electron density in some interaction zones is higher than 3×1019 cm-3, which indicates that each Air Molecule there is ionized.

F Liu - One of the best experts on this subject based on the ideXlab platform.

  • tightly focused femtosecond laser pulse in Air from filamentation to breakdown
    Optics Express, 2010
    Co-Authors: Xiaolong Liu, X Y Liu, F Liu, Jie Zhang
    Abstract:

    The propagation of tightly focused femtosecond laser pulse with numerical aperture of 0.12 in Air is investigated experimentally. The formation and evolution of the filament bunch are recorded by time-resolved shadowgraph with laser energy from 2.4 mJ to 47 mJ. The distribution of electron density in breakdown area is retrieved using Nomarski interferometer. It is found that intensity clamping during filamentation effect still play a role even under strong external focusing. The electron density in some interaction zones is higher than 3×1019 cm-3, which indicates that each Air Molecule there is ionized.

X Y Liu - One of the best experts on this subject based on the ideXlab platform.

  • tightly focused femtosecond laser pulse in Air from filamentation to breakdown
    Optics Express, 2010
    Co-Authors: Xiaolong Liu, X Y Liu, F Liu, Jie Zhang
    Abstract:

    The propagation of tightly focused femtosecond laser pulse with numerical aperture of 0.12 in Air is investigated experimentally. The formation and evolution of the filament bunch are recorded by time-resolved shadowgraph with laser energy from 2.4 mJ to 47 mJ. The distribution of electron density in breakdown area is retrieved using Nomarski interferometer. It is found that intensity clamping during filamentation effect still play a role even under strong external focusing. The electron density in some interaction zones is higher than 3×1019 cm-3, which indicates that each Air Molecule there is ionized.