Temporal characterization of a self-modulated laser wakefield

摘要

The temporal envelope of plasma density oscillations in the wake of an intense (I ∼ 4×1018 W/cm2,I∼4×1018W/cm2, λ = 1 μmλ=1μm) laser pulse (400 fs) is measured using forward Thomson scattering from a copropagating, frequency doubled probe pulse. The wakefield oscillations in a fully ionized helium plasma (ne = 3×1019 cm−3)(ne=3×1019cm−3) are observed to reach maximum amplitude (δne/ne ∼ 0.1)(δne/ne∼0.1) 300 fs after the pump pulse. The wakefield growth (4 ps−1)(4ps−1) and decay (1.9 ps−1)(1.9ps−1) rates are consistent with the forward Raman scattering instability and beam loading, respectively. © 1997 American Institute of Physics.