Laser-Generated Ultrashort Multi-Megagauss Magnetic Pulses in Plasmas

High-resolution measurements of the spatial and temporal evolution of megagauss magnetic fields created in intense short-pulse laser-plasma interactions

A pump-probe polarimetric technique is demonstrated, which provides a complete, temporally and spatially-resolved mapping of the megagauss magnetic fields generated in intense short-pulse laser-plasma interactions. A normally-incident time-delayed probe pulse reflected from its critical surface undergoes a change in its ellipticity according to the magneto-optic Cotton-Mouton effect due to the azimuthal nature of the ambient self-generated megagauss magnetic fields. The temporal resolution of the magnetic field mapping is of the order of the pulsewidth, whereas a spatial resolution of a few mi…

飞秒超强激光-固体相互作用中微小磁场至兆高斯量级的10$^4$倍放大

10$^4$-fold amplification of a tiny magnetic field to megagauss scale in femtosecond, ultraintense laser-solid interaction

本研究利用超强飞秒激光与钕磁铁固体相互作用，将10$^{-3}$兆高斯弱磁场放大至数十兆高斯，并通过PIC模拟揭示轴向磁场放大的发电机机制。

Propagation of an ultrashort electromagnetic pulse in solid-state plasma

The change of the shape of an ultrashort electromagnetic pulse in its propagation in solid-state plasma was calculated in the linear approximation. A case of solid-state silver plasma and of a "Mexican hat" wavelet pulse was considered. The dielectric permittivity of the medium was calculated in the Drude model. Strong dispersion spreading of a pulse at distances of the order of several microns was shown, and the comparison of evolution of the pulse shape for different center frequencies was carried out.

Numerical simulation of copper ablation by ultrashort laser pulses

Using a modified self-consistent one-dimensional hydrodynamic lagrangian fluid code, laser ablation of solid copper by ultrashort laser pulses in vacuum was simulated to study fundamental mechanisms and to provide a guide for drilling periodic microholes or microgratings on the metal surface. The simulated laser ablation threshold is a approximate constancy in femtosecond regime and increases as the square root of pulse duration in picosecond regime. The ablation depth as a function of pulse duration shows four different regimes and a minimum for a pulse duration of ~ 12ps for various laser fl…

Wakefield Excited by Ultrashort Laser Pulses in Near-Critical Density Plasmas

Laser wakefield acceleration (LWFA) using high repetition rate mJ-class laser systems brings unique opportunities for a broad range of applications. In order to meet the conditions required for the electron acceleration with lasers operating at lower energies, one has to use high density plasmas and ultrashort pulses. In the case of a few-cycle pulse, the dispersion and the carrier envelope phase effects can no longer be neglected. In this work, the properties of the wake waves generated by ultrashort pulse lasers in near-critical density plasmas are investigated. The results obtained may lead…

Absorption of Ultrashort Laser Pulses in Strongly Overdense Targets

We report on the first absorption experiments of sub-10 fs high-contrast Ti:Sa laser pulses incident on solid targets. The very good contrast of the laser pulse assures the formation of a very small pre-plasma and the pulse interacts with the matter close to solid density. Experimental results indicate that p-polarized laser pulses are absorbed up to 80 percent at 80 degrees incidence angle. The simulation results of PSC PIC code clearly confirm the observations and show that the collisionless absorption works efficiently in steep density profiles.