The temporal envelope of plasma density oscillations in the wake of an intense (I˜4 × 1018 W/cm2, λ = 1 μm) 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) are observed to reach maximum amplitude (δne/ne˜0.1) 300 fs after the pump pulse. The wakefield growth (3.5 ps-1) and decay (1.9 ps-1) rates are consistent with the forward Raman scattering instability and Landau damping, respectively.
ASJC Scopus subject areas
- Physics and Astronomy(all)