K-shell Spectroscopy of Plasmas Created by Intense Laser Irradiation of Micron-scale Pyramid and Sphere Targets

Abstract K-shell spectra of targets with microstructured features irradiated by an intense femtosecond laser have been studied. Examination of K α emission from laser irradiated Si targets coated with micron-scale polystyrene spheres indicates that the emission is enhanced by a factor of ∼3 over emission from planar solids. Sphere-coated targets also emit K-shell He-like Si radiation indicating the presence of a hot dense plasma beneath the microspheres. Furthermore, K α from Ti foils coupled to micro-tipped reentrant pyramid and wedge shaped targets has been studied, however, no significant enhancement of the K α yield is observed for these kinds of targets. These studies illustrate that, with correct tailoring of the target surface, field enhancements can be used to increase X-ray emission from intensely irradiated targets.