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UNR activities in FSC

UNR activities in FSC. Y. Sentoku and T. E. Cowan. $40K from FSC to support a graduate student, Brian Chrisman, “Numerical modeling of fast ignition physics”. List of activities. Modeling of cone-guiding fast ignition by PICLS.

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UNR activities in FSC

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  1. UNR activities in FSC Y. Sentoku and T. E. Cowan $40K from FSC to support a graduate student, Brian Chrisman, “Numerical modeling of fast ignition physics”.

  2. List of activities • Modeling of cone-guiding fast ignition by PICLS. • Hot electron temperature scaling by changing the cone target density. (B. Chrisman) • Modeling of nail target experiment. (Collaboration with UCSD) • Perfect energy conservation scheme of relativistic collision between weighted particles. (previous model conserves energy and momentum statistically.)

  3. Summary of Cone-Guiding Fast Ignition Simulation • The Weibel instability occurs below and around 100nc density. No magnetic filament appears around the core. • The dominant core heating mechanism is identified as drag heating between hot and bulk electrons and consequent energy cascading from the bulk electrons to the core ions. • Hot electron temperature is inversely proportional to the square root of the cone target density,Th [MeV] ~ (I/1019 W/cm2•m2)•(nt/nc)1/2 , nt: target density,after preplasma is blown off by the laser pressure. Hot electron temperature is tunable by changing the cone target density. Laser intensity: 1020 W/cm2 Cone-Guiding Fast ignition simulation Electron energy density evolution

  4. The Weibel instability occurs below and around 100nc density. No magnetic filament appears around the core. Laser intensity: 1020 W/cm2 Kinetic instabilities are collisionally dumped in high density region > 100nc.

  5. Electron acceleration distance shrinks after pre-plasma blown off by super intense laser irradiation 1/2 (a) Preplasma (L>λs0) Interaction (acceleration) length L=λs0=c/ω0 Ponderomotive scaling plasma skin length at cut-off: λs0 [MeV] Steepened by photon pressure (b) After preplasma blown off (L<λs0) Interaction (acceleration) length L=λs=γ1/2•c/ωps plasma skin length of solid density: λs Acceleration distance will be (γnc/ns)1/2 shorter in the steep case, then Modified Ponderomotive scaling

  6. Demonstration of Modified Th scaling by PIC- Th ∝ 1/sqrt(n) - Laser intensity: 1020 W/cm2 Energy coupling is calculated in 2.5m spot along the laser- axis behind the cone target. 2D results by changing cone target density After the pre-plasma has been blown away, the hot electron temperature drops, though energy coupling from the laser to hot e- stays almost constant.

  7. Comparison cone/cone+wire - radiography LULI-100 TW (July 2006): J. Fuchs, M. Borghesi, O. Willi, R. Kodama, et al. (+UNR students) time Quasi-half spherical expansion from tip Propagation of fast electrons along wire @ ~c time

  8. time LULI-100 TW (July 2006): J. Fuchs, M. Borghesi, O. Willi, R. Kodama, et al. (+UNR students)

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