Temporally and spatially resolved harmonic emission from spherical laser fusion targets

Abstract

An electro‐optic streak camera was used to record 2ω₀ and (3/2) ω₀ harmonic emission from glass microsphere targets irradiated with a 0.3‐TW Nd : glass laser. These two harmonic frequencies are produced at the critical and quarter‐critical surfaces, respectively, and thus provide a measure of these electron‐density trajectories. After applying a refraction correction to the data, the trajectories were compared with predictions from the KMSF TRHYD code. It was found that hydrodynamic development in the critical‐density region was accurately depicted by the temporal behavior of the 2ω₀ emission. In addition, observed periodic fluctuations in (3/2) ω₀ emission along a meridian give direct evidence of density rippling in the underdense corona.