Femtosecond-Laser-Driven Cluster-Based Plasma Source for High-Resolution Ionography

The intense isotropic source of multicharged ions, with energy above 300 keV, was produced by femtosecond Ti:Sa laser pulses irradiation (intensity of ~ 4xl0(17) W/cm(2)) of the He and CO(2) gases mixture expanded in supersonic jet. High contrast ionography images have been obtained for 2000 dpi metal mesh, 1 urn polypropylene and 100 nm Zr foils, as well as for different biological objects. Images were recorded on 1 mm thick CR-39 ion detector placed in contact with back surface of the imaged samples, at the distances 140-160 mm from the plasma source. The obtained spatial resolution of the image was ~ 600 nm. A 100 nm object thickness difference was resolved very well for both Zr and polymer foils. The multicharged ion energy for Carbon and Oxygen ions passing through the 1 urn polypropylene foil is estimated to give the energy of more than 300 keV. An almost equal number of ions were measured with total number of about 10(8) per shot at a different direction from plasma source. Easy production of different sub-MeV ions in wide space angle, recognizes femtosecond-laser-driven-cluster-based plasma as a well-suited bright source for novel type of submicron ionography to image different media, including nanofoils, membranes, and other low-contrast objects.