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Divergence, Instabilities, and Deposition: SESSION REPORT

Divergence, Instabilities, and Deposition: SESSION REPORT. Chairs: L.Gremillet, A.P.L.Robinson,C-K.Li 10 th International Fast Ignition Workshop. Divergence. Recognized as an important issue. Laser-solid experiments indicate divergent flows.

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Divergence, Instabilities, and Deposition: SESSION REPORT

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  1. Divergence, Instabilities, and Deposition:SESSION REPORT Chairs: L.Gremillet, A.P.L.Robinson,C-K.Li 10th International Fast Ignition Workshop

  2. Divergence • Recognized as an important issue. • Laser-solid experiments indicate divergent flows. • Diagnosis and Interpretation of Laser-solid experiments debated. • Origin of fast electron divergence debated. • Beam Instabilities? Absorption details? • Outcome may be different in fully integrated FI scenario! • New ideas for mitigating or controlling divergence were suggested. More work needed.

  3. Electron beam divergence Lancaster et al, PRL, 98, 125002 Green et al, PRL, 100, 015003 32o 76o 29o 54o 35o Kalpha/probe A – 5ps, defocused spot, I = 1.5 x 1019 W/cm2 Kalpha B – 5ps, focused spot, I = 4 x 1019 W/cm2 I = 5 x 1020 W/cm2

  4. Simulation Experiment

  5. Instabilities • Extensive summary given by LG. • New instability presented by Tony Bell. • Suggests that picture might be different on 10ps timescale. • How can we properly see instabilities in experiments (Stoeckl & Stephens) • More clarity from theorists! • Diagnostic approaches: X-rays (KL), CTR/OTR (CB), Protons (Patel and Roth)…?

  6. Energetic particles coupled to MHD plasma Lucek & Bell (2000) applied to cosmic rays Demonstrated dB/B>>1

  7. tilted filaments coalescence process L. O. Silva 6th DDFIW (2008) R. Evans 6th DDFIW (2008) nb/np = 0.3-0.5 ? nb/np = 1 injection of e-i stream How fastest-growing modes evolve from periodic systems to semi-infinite ones ?

  8. Deposition • Summary given by CKL. • Confident about understanding of deposition and scattering. • Collisionless ion heating mechanism discussed by R.Trines (paper by N.Sircombe) • CKL also presented measurements of E-fields in imploded fuel. Implications for FI?

  9. From talk by Trines Electrondistribution Iondistribution

  10. Radial E field at peak compression of cone-in-shell implosion? Strength of E field in an ignition target, >1010 V/m ? Increase electron range? Enhance electron collimation? e

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