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An ultra fast, sub-picosecond resolution streak camera has been recently developed at the LLNL. The camera is a versatile instrument with a wide operating wavelength range. The temporal resolution of up to 300 fs can be achieved, with routine operation at 500 fs. The streak camera has been operated in a wide wavelength range from IR to x-rays up to 2 keV. In this paper we briefly review the main design features that result in the unique properties of the streak camera and present its several scientific applications: (1) Streak camera characterization using a Michelson interferometer in visible range, (2) temporally resolved study of a transient x-ray laser at 14.7 nm, which enabled us to vary the x-ray laser pulse duration from {approx}2-6 ps by changing the pump laser parameters, and (3) an example of a time-resolved spectroscopy experiment with the streak camera.

The propagation of laser-generated hot electrons through matter and across narrow vacuum gaps is studied. We use the ATLAS titanium-sapphire laser of Max-Planck-Institut fuer Quantenoptik to irradiate 10 {proportional_to}m to 100 {proportional_to}m thick copper foils at intensities up to 10{sup 19} W/cm{sup 2}, generating electrons with temperatures in the MeV-range. After propagating through the target the electrons are detected via Cerenkov radiation generated in a suitable medium and by hard X-rays emitted from an X-ray ''fluor''. In some experiments a plastic scintillator was used to monitor the electrons. These diagnostics allow to characterize the electrons with respect to their energy, number and directionality. We also investigate the propagation of the hot electrons across narrow vacuum gaps, with a width ranging from several 100 {proportional_to}m down to 25 {proportional_to}m. The effect of self-generated fields in preventing electrons to cross the gap is demonstrated. Implications of these experiments with respect to pumping of X-ray lasers, isochoric heating by X-rays and developing optics for 4th-generation light sources will be discussed.