High Power Laser Science and Engineering, Volume. 5, Issue 3, 03000e17(2017)
Targets for high repetition rate laser facilities: needs, challenges and perspectives On the Cover
Fig. 1. Schematic view of the experimental setup used at the MEC endstation of the LCLS to study dynamic compression of graphite samples to pressures between 20 and 230 GPa. The VISAR system recorded the shock transit time providing information on the shock velocity. The microscopic state was probed by XRD. Image reproduced from Ref. [10], licensed under CC-BY 4.0[19].
Fig. 2. Examples of typical multilayer targets used for dynamic compression physics experiments: (a) in the simplest configuration the sample is coated with a low-Z layer (ablator), and occasionally with a preheat layer; (b) placing the sample layer between solid plates prevents expansion and maintains high-pressure conditions longer; (c) complex sample allows measurement of shock pressure by VISAR reflection from pressure standard (quartz) while also containing the sample.
Fig. 3. Scheme of iron–nickel alloy samples produced for ESRF experiments using an integrated process including four steps performed by different companies.
Fig. 4. Schematic layout of the experimental configuration used to investigate proton-driven isochoric heating of polycrystalline graphite rods
Fig. 5. Qualitative spatial distributions of electric field (left) and electron energy density (right) produced by the interaction of an ultra-intense laser pulse with a flat-top cone target. From T. Kluge.
Fig. 6. (a) Hollow cone target with thin wire at the tip (diameter
Fig. 7. 2D spatial distribution of free electron density and longitudinal electrostatic field at 43 fs prior to the peak laser intensity on the target. The density distribution shows that internal expansions compress the CD
Fig. 8. Simulated energy density distribution showing the growth of seeded Rayleigh–Taylor instabilities in samples with an initial surface roughness containing several spatial frequencies. For each image, the black bar illustrates the maximum spatial frequency of the initial roughness, the minimum spatial frequency is twice this size. Reproduced from Ref. [40], with the permission of AIP publishing.
Fig. 9. Scanning electron microscopy (SEM) micrograph of a grating with period around
Fig. 10. Schematic illustration of the production of X-rays in the interaction between a laser pulse and a gas target. The betatron motion of electrons propagating in the pulse wake results in the emission of synchrotron radiation.
Fig. 11. Adjustable length gas cell developed by SourceLAB. Courtesy of F. Sylla.
Fig. 12. Cross-section and assembly of fast electro-valve and nozzle for sub-millimetre He gas jets with peak density above
Fig. 13. Schematic illustration of TNSA – relativistic electrons produced in laser–matter interaction propagate through the target and form an electron sheath at the target rear surface producing a charge separation and intense electric fields.
Fig. 14. Schematic illustration of laser-driven ion acceleration from a metallic foil with a hydrogen-rich micro-dot on the back side. Reprinted with permission from Macmillan Publishers Ltd: Nature[77], copyright 2006.
Fig. 15. SEM microscope images of a single layer of polystyrene spheres (a) with diameter
Fig. 17. (a) Schematic view of a flat target grounded through a coil. The return current flowing in the coil produces electric fields allowing for energy selection, collimation and post-acceleration of laser-driven ions: (b) shows a scheme of the electric field configuration in the coil (snapshot), (c) and (d) illustrate the electric field profiles inside the coil along the coil axis and in the transverse plane at the location of the peak of charge density along the coil. Image reproduced from Ref. [94], licensed under CC-BY 4.0[19].
Fig. 18. SEM micrographs of poly(4-methyl-1-pentene) foams prepared from (a), (b) 1-hexanol, (c) 2-methyl-1-pentanol, (d) 2-ethyl-1-butanol. Image reproduced from Ref. [109]. Copyright 2002 The Japan Society of Applied Physics.
Fig. 19. (a) LSTI: wiper and frame with a 4 mm aperture. (b) Liquid crystal targets with four different thicknesses. Thickness is a function of the blade sliding velocity. (c) Film production process: the blade slides across the aperture drawing the liquid. The film is formed within
Fig. 20. Target fabrication and delivery process: flow chart. From N. Alexander (GA-IFT).
Fig. 21. SEM micrographs characterizing the surface quality of planar targets. (a) Al film deposited on Si wafer by magnetron sputtering. The inset shows a cross-section of the same film. Roughness measured by AFM is around 10 nm. (b) Commercial Ti foil (thickness
Fig. 22. Computer vision and force sensing have been added to the fixture-based robotic planar target assembly station. Unpublished from N. Alexander and P. Fitzsimmons (GA-ICF).
Fig. 23. Target damage observed for a sheet of Ti
Fig. 24. Targets mounted on thin foils. (a)
Fig. 25. Fast target positioning system developed for the ELIMAIA interaction area, ELI-Beams. From T. Wiste.
Fig. 26. Concept model of a ladder positioning system, composed of: a ladder supply cassette loaded with new targets; a motorized arm to pull out ladders from the cassette; precision motors to place the target at laser focus; a drop-off cassette receiving used ladders. From N. Alexander (GA-IFT).
Fig. 27. Target fielding system concept, utilizing mechanism of cinema film projector, mounts targets on carbon fibres over holes in linked belts or continuous steel film strips (not shown). Target quantities in excess of
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I. Prencipe, J. Fuchs, S. Pascarelli, D. W. Schumacher, R. B. Stephens, N. B. Alexander, R. Briggs, M. Büscher, M. O. Cernaianu, A. Choukourov, M. De Marco, A. Erbe, J. Fassbender, G. Fiquet, P. Fitzsimmons, C. Gheorghiu, J. Hund, L. G. Huang, M. Harmand, N. J. Hartley, A. Irman, T. Kluge, Z. Konopkova, S. Kraft, D. Kraus, V. Leca, D. Margarone, J. Metzkes, K. Nagai, W. Nazarov, P. Lutoslawski, D. Papp, M. Passoni, A. Pelka, J. P. Perin, J. Schulz, M. Smid, C. Spindloe, S. Steinke, R. Torchio, C. Vass, T. Wiste, R. Zaffino, K. Zeil, T. Tschentscher, U. Schramm, T. E. Cowan. Targets for high repetition rate laser facilities: needs, challenges and perspectives[J]. High Power Laser Science and Engineering, 2017, 5(3): 03000e17
Special Issue: TARGET FABRICATION
Received: Nov. 16, 2016
Accepted: May. 11, 2017
Published Online: Nov. 21, 2018
The Author Email: I. Prencipe (i.prencipe@hzdr.de)