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Bremsstrahlung measurements of electron divergence. Cliff Chen. August 5, 2010. Special FSC Meeting on Electron Divergence in Fast Ignition. The angular distribution of Bremsstrahlung emission constrains the divergence angle and conversion efficiency. Ag Foil Target.
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Bremsstrahlung measurements of electron divergence Cliff Chen August 5, 2010 Special FSC Meeting on Electron Divergence in Fast Ignition
The angular distribution of Bremsstrahlung emission constrains the divergence angle and conversion efficiency Ag Foil Target Injected Electron Distribution 1.2 MeV 1-Temp CEA 0 deg 20 deg HA exp(-(theta/50deg)^4) EdN/dOmega (MeV/SR/e-) 75 deg HA Angle (degrees) The angular distribution of Bremsstrahlung may be useful for inferring the electron divergence angle.
Diagnostic Setup Al & Ag:1x1 mm CH: 5x10 mm 16° 10 Al / 500 Ag / 1mm CH 35° 0.7 ps, 7 μm FWHM, Ipeak≈1020 W/cm2 ≈10 mJprepulse 0° 6° 28° 66°
3 rear surface spectrometers are simultaneously fit using Monte Carlo modeling of an electron beam Bremsstrahlung emission matrix calculated for each: -Spectrometer Location -Max Injection Angle e- injected isotropically with max angle Central Angle can also be varied • 2-T electron distributions are simultaneously fit to each spectrometer for each angular distribution • Minimum reduced χ2 is calculated for each angle parameter 157 J 148 J 40 J
Electron Divergence in Planar Geometry 157 J 40 J 66° 0° 0° 66° 28° 28° Best Fit = 60±5°, ηLe-=32% Fitting hν > 100 keV = 50±5°, ηLe-=36% Best Fit = 60±5°, ηLe-=30% Fitting hν > 100 keV = 50±5°, ηLe-=34%