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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.

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First 14 MeV neutron images of imploded microballoons have been obtained at the Phébus laser facility at CEL-V in 1992 [Garconnet et al. Laser Part Beams 11, 3 (1994)]. The sizes of the neutron source have been measured by using a coded-aperture imaging system and a scintillator array as a detector. The threshold of the experimental setup was typically 2×1010 neutrons/shot. 600–800 μm source sizes in direct drive experiments have been measured with a 130 μm two-point resolution. In 1993 we improved the sensitivity of the camera by increasing the light collection efficiency. It can now work at a neutron yield as small as a few 108. Thanks to this improvement some images in indirect drive experiments have been recorded in the range 3×108–5×109 with a 56 μm two-point resolution. Wiener filter, homomorphic Wiener filter, and Nugent’s ‘‘comb filter’’ methods have been used and compared to deconvolve the penumbral images. Design of the camera and numerical method performances will be discussed.

A plane grid probe is operated in a cesium-vapor-discharge plasma. The collected electron and ion currents are separated. The characteristic curve and its second derivative are analyzed. The densities, temperatures, and plasma potentials deduced from these curves are given and compared. .