PIC modeling of fast electron transport in plasmas

Understanding fast electron transport in plasma is crucial for fast ignition. A recent experiment [1] using the OMEGA EP laser (1 kJ/10 ps) study of fast electrons transport from the Au layer into hot (40 eV) dense (30 mg/cc) plasma created by shock heating of CH foam sandwiched between Au and Cu tracer layer, showed a strong reduction (20$\times )$ in Cu K$\alpha {\rm g}$yield compared to the cold target with a uniform and weak K$\alpha $ spot. To understand this transport experiment, 2D collisional PIC simulations, using the PICLS code, are performed to model fast electron transport in such plasma transport target. Simulations show a significant increase in fast electron divergence going from high density Au to less dense plasma transport layer due to strong B-fields generated at the Au/CH plasma interface. Fine B-field structures in plasma are also observed, possibly responsible for further electron scattering resulting in poor K$\alpha $ yield.\\[4pt] [1] T Yabuuchi, ``Study of fast electron transport in plasmas using a kJ-class laser pulse,'' IFSA 2011