Laser Plasma Interactions & Related Diagnostics

Thomson scattering is widely used to measure plasma temperature, density, and flow velocity in laser-produced plasmas at Trident, and is also used to detect plasma waves driven by unstable and nonlinear processes. A typical configuration uses a low intensity laser beam (2^nd, 3^rd, or 4^th harmonic of 1054-nm) to probe a plasma volume. The Thomson scattered light is collected by a lens and is measured using a spectrometer coupled to a gated or streaked camera. The range of plasma wave numbers probed is determined by the Thomson probe beam wavelength and scattering geometry. Thomson scattering is routinely used at Trident in various configurations including self-Thomson scattering, imaging Thomson scattering, streaked Thomson scattering, and to obtain “ω-k” plasma wave dispersion. The Thomson scattered spectrum can be measured with temporal resolution ~ 10 ps, spatial resolution ~ 10-µm, and spectral resolution ~ 0.5 Å

Streaked Thomson scattering from electron plasma waves in a gas jet laser produced plasma. The probe laser is a 1-ns pulse, followed by three 100-ps pulses. The time-dependent plasma density can be deduced from the spectral shifts.