In 1948, P. Kirkpatrick and A. V. Baez developed an x-ray microscope ͑energy range about 100 eV-10 keV͒ composed of two concave spherical mirrors working at grazing incidence. That device, named KB microscope, presents a 3-5 m resolution within a field having a radius about 100 m; outside that field, its resolution lowers rapidly when the object point recedes from the center. The adjunction of two similar mirrors can notably increase the useful field ͑typically, the resolution can be better than 10 m within a 2-mm-diam field of view͒, which is necessary for studying laser plasmas. Its main advantage with respect to more simple optics, as the pinhole, is that it can be located far enough from the plasma to avoid any destruction during the shot. We describe such a microscope that we call KBA microscope and present some images of fine metallic grids. Those grids were backlighted by x-ray sources, either a cw one or a series of laser plasmas from the Octal-Héliotrope facility. Examining the films in detail shows that the experimental results are very close to the theoretical characteristics; hence the interest of this device for the x-ray diagnostics on the future powerful laser facilities.

A transmission grating streaked spectrograph (SPARTUVIX) has been developed at the Centre d’Etudes de Limeil-Valenton for measuring the temporal evolution of soft-x-ray spectra in laser-produced plasmas. In this article the ideas behind the instrument are described as well as a description of the actual working diagnostic and its relevant components. This diagnostic has been used to look at the time behavior of x-ray laser emission, and a number of very interesting results have been obtained. A representative sample of these results will also be shown.

This paper describes the use of a deflecting magnetic field to reduce the duration of an electron pulse from a Febetron 707 (normally 90 nsec at the base, Imax=4000 A) to 12 nsec (6–7 nsec half-width) with Imax =450 A. Under these conditions a dose of about 300 kilorad is delivered in a circular area 2 cm in diameter.

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