Multilayer optics for monochromatic high-resolution x-ray imaging mircoscopes

Within the framework of its researches on Inertial Confinement Fusion (ICF), the “Commissariat a l’Energie Atomique et aux Energies Alternatives” (CEA) studies and designs advanced X-ray diagnostics in order to probe dense plasmas produced by Laser facilities. The final goal for those diagnostics is to be used during experiments on the Laser Megajoules french facility (LMJ) at Bordeaux. We present two types of advanced monochromatic High Resolution X-ray Imaging microscopes (HRXI) who have high spatial resolution capability (3-6 µm) and high efficiency. The first microscope so-called MERSSIX consists of two toroidals mirrors mounted into a Wolter type geometry and working at grazing incidence. Non-periodic multilayer (depth graded) mirrors were developed with special coatings designed to provide broadband X-ray reflectance in the 1 - 22 keV energy range. Associated to this Wolter microscope a potential monochromatic third mirror coated with a multilayer stack can be used for monochromatic application in that range. The second microscope is composed of a transmission gold Fresnel Phase Zone Plate (FPZP) and a narrow bandwidth multilayer mirror. We present an experimental study with X-ray plasma-source and a complete characterization of the X-ray optics on the synchrotron radiation facility BESSY II. Potentialities (a few µm spatial resolution monochromatic images) and complementarity of these two monochromatic HRXI are discussed. The design of the MLs for each microscope is detailed. Keywords : Inertial confinement fusion, Plasma, X-ray microscopy, grazing X-ray microscope, Non-periodic multilayer, multilayer mirror, Super-mirror 1. INTRODUCTION The Laser MegaJoule (LMJ) [1-3] is commissioned by the French Commissariat a l’Energie Atomique (CEA) at CESTA laboratory near Bordeaux in France. The LMJ is dedicated to high energy density physics experiments, and among these, to obtain ignition and fusion of the DT fuel inside. LMJ will consist of 176 neodynium glass laser lines arranged in 8 beams bundles focused as 44 quads of 4 beams. Laser energy will be about 1.4 MJ at 0.35 µm. LMJ is commissioned in 2014 The principle of ICF experiments is to reach ignition with the implosion of a mm size diameter deuterium-tritium (DT) filled capsule at the center of 1 cm-long conversion cavity; the 176 very intense laser beams are focused on the inner side of the conversion cavity, which produce then a large amount of X-rays .