X-ray emission produced by hot electrons from fs-laser produced plasma - diagnostic and application

High intensity fs-laser pulses can deliver focused intensities in the regio n of 10(16)-10(19) W/cm(2). If the laser pulse is focused onto a solid or g aseous material, a plasma is created. The electrons, as well as the ions ar e accelerated in the strong laser field up to energies in the range of keV to several MeV. The interaction of the high energy particles with cold mate rial, that is, the solid target yield of intense X-ray emission, K-shell-as well as bremsstrahlung-radiation. The K-shell emission from layered target s is a useful indicator of the production efficiency, energy distribution, and transport of hot electrons produced in fs-laser plasmas. For the diagno sis of laser plasma interaction and its application as an intense X-ray sou rce, the spatial, temporal and spectral distribution of K-shell X rays is o f fundamental importance. Focusing crystal spectrographs can be used to obt ain a single shot X-ray spectra of laser plasmas produced by table tbp fs-l asers. With a spatial- and spectral-focusing spectrograph based on a toroid ally bent crystal, the emission region of the hot plasma and K alpha-radiat ion can be determined. Recording the spectra online by a frontside illumina ted charge-coupled device (CCD) allows alignment of the crystal spectrograp h, as well as the laser beam focusing leading to different X-ray source siz es. Using a controlled fs-prepulse, an increase in K alpha radiation could be observed with the diagnostic. Measurements of calibrated high resolution spectra are compared with partic le-in-cell (PIC) calculations of the laser absorption and hot electron prod uction postprocessed by a Monte Carlo (MC) transport model of electron stop ping and K alpha X-ray generation.