TEMPORALLY AND SPATIALLY RESOLVED HARMONIC EMISSION FROM SPHERICAL LASER FUSION-TARGETS

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.