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Fast Ignition Workshop Pravesh Patel

Fast Ignition Workshop Pravesh Patel. Proton Fast Ignition. Focusability of the proton beam Rear surface thermal measurements (optical, XUV) Quantitative technique based on direct characterision of the proton beam as it goes through focus.

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Fast Ignition Workshop Pravesh Patel

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  1. Fast Ignition Workshop Pravesh Patel

  2. Proton Fast Ignition • Focusability of the proton beam • Rear surface thermal measurements (optical, XUV) • Quantitative technique based on direct characterision of the proton beam as it goes through focus

  3. XUV emission measurements with 400J incident laser energy Planar foil 1mm diameter foil 360µm diameter foil 500µm 280µm FWHM 94µm FWHM 45µm FWHM Increasing signal intensity

  4. Rear surface temperature from focused proton-heated foils Comparison of absolute XUV signal with LASNEX simulations gives peak temperatures of 200eV at rear surface

  5. A quantitative technique for characterizing proton focusing Beam distribution at focal plane Counts 80µm 32µm B. Zhang et al. 100 200 300 400 Distance D (µm) 80% of energy is contained within a 32µm diameter spot Protons focused from a 120µm diameter region x10-20 enhancement

  6. LSP simulations indicate focusability can be improved further 10µm 50µm More uniform laser irradiation produces better focused beam Requires higher laser energies (to maintain intensity over larger area)

  7. Proton conversion efficiency can be enhanced by tailoring the atomic surface composition • Higher Z atomic mixture increases separation between proton and ion fronts and differentially puts more energy into protons • Tailored surface can increase hydrogen density, and provide a deeper source of protons compared to thin contaminant layers Solid Hydrogen Hydrides Contaminants M. Foord et al., J. Appl. Phys. 103, 056106 (2008) D. Offermann et al., submitted (2008) Increase of 25% in conversion efficiency with ErH targets has been demonstrated in recent experiments

  8. 6.4MeV 8.4MeV 10.1MeV 245µm 190µm 140µm Characterizing the proton source 8-12Å layer of H20.CH2 Au Protons originate from a 250µm diameter, very thin 8-12Å layer, at the rear surface

  9. Hybrid Particle-in-Cell (PIC) modeling can reproduce most features of proton acceleration LSP (Large Scale Plasma) Simulation 8-12Å layer of H20.CH2 r (µm) Au M Foord et al. HEDP 3, 365 (2007) z (µm) LSP reproduces energy spectrum, peak energy, and divergence Simulations confirm rapid acceleration and initial pulse duration (ps)

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