Electron-scale dynamics of the diffusion region during symmetric magnetic reconnection in space.

Magnetic reconnection is an energy conversion process that occurs in many astrophysical contexts including Earth's magnetosphere, where the process can be investigated in situ by spacecraft. On 11 July 2017, the four Magnetospheric Multiscale spacecraft encountered a reconnection site in Earth's magnetotail, where reconnection involves symmetric inflow conditions. The electron-scale plasma measurements revealed (i) super-Alfvénic electron jets reaching 15,000 kilometers per second; (ii) electron meandering motion and acceleration by the electric field, producing multiple crescent-shaped structures in the velocity distributions; and (iii) the spatial dimensions of the electron diffusion region with an aspect ratio of 0.

Spectroscopic temperature determination of aluminum monoxide in laser ablation with 266-nm radiation.

We report time-resolved measurements of diatomic aluminum monoxide spectra in the study of laser ablation by the use of frequency-quadrupled 266 nm Nd:YAG laser radiation. Spectroscopic temperatures of 3432(35) K and 3329(13) K are obtained at a delay time of 20mu, respectively, by the use of the modified diatomic Boltzmann plot and by the use of the Nelder-Mead algorithm in the fitting of the recorded spectrum.

Computational fluid-dynamic model of laser-induced breakdown in air.

Temperature and pressure profiles are computed by the use of a two-dimensional, axially symmetric, time-accurate computational fluid-dynamic model for nominal 10-ns optical breakdown laser pulses. The computational model includes a kinetics mechanism that implements plasma equilibrium kinetics in ionized regions and nonequilibrium, multistep, finite-rate reactions in nonionized regions. Fluid-physics phenomena following laser-induced breakdown are recorded with high-speed shadowgraph techniques.