X-ray imaging technology is highly developed to meet the needs of high-energy physics and diagnostics of inertial
confinement fusion. In this paper, we describe the design of a non coplanar toroïdal mirrors microscope. It consists of
three off-axis revolution concave toroïdal mirrors working at grazing incidence. Non-periodic W/SiC multilayer coatings
have been deposited on each mirror, in order to increase until 10 keV the bandpass of reflectivity of the microscope.
These super mirrors have been designed to work at 0.6° grazing incidence angle and display a reflectivity better than
40% in the entire energy range 2-10 keV. Concerning the imaging performances, we have almost achieved 5 μm of
spatial resolution in a field of 500 μm. Regarding to these results, this prototype of microscope, the so-called "Plasma
Imageur X pour les Experiences Laser Mega Joule" (PIXEL), will be used for 2D spatial and 1D time resolved imaging
of dense plasmas produced during inertial confinement fusion experiments at the future Laser Mega Joule French facility
(LMJ).
Periodic multilayers of nanometric period are widely used as optical components for the X-ray and extreme UV
(EUV) ranges, in X-ray space telescopes, X-ray microscopes, EUV photolithography or synchrotron beamlines for
example. Their optical performances depend on the quality of the interfaces between the various layers: chemical
interdiffusion or mechanical roughness shifts the application wavelength and can drastically decrease the reflectance.
Since under high thermal charge interdiffusion is known to get enhanced, the study of the thermal stability of such
structures is essential to understand how interfacial compounds develop. We have characterized X-ray and EUV siliconcontaining
multilayers (Mo/Si, Sc/Si and Mg/SiC) as a function of the annealing temperature (up to 600°C) using two
non-destructive methods. X-ray emission from the silicon atoms, describing the Si valence states, is used to determine
the chemical nature of the compounds present in the interphases while X-ray reflectivity in the hard and soft X-ray
ranges can be related to the optical properties. In the three cases, interfacial metallic (Mo, Sc, Mg) silicides are evidenced
and the thickness of the interphase increases with the annealing temperature. For Mo/Si and Sc/Si multilayers, silicides
are even present in the as-prepared multilayers. Characteristic parameters of the stacks are determined: composition of
the interphases, thickness and roughness of the layers and interphases if any. Finally, we have evidenced the maximum
temperature of application of these multilayers to minimize interdiffusion.
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