Prof Peter Norreys FInstP;

Abstract:

We report on shadowgraphic measurements showing the first space- and time-resolved snapshots of ultraintense laser pulse-generated fast electrons propagating through a solid target. A remarkable result is the formation of highly collimated jets (<20-μm) traveling at the velocity of light and extending up to 1 mm. This feature clearly indicates a magnetically assisted regime of electron transport, of critical interest for the fast ignitor scheme. Along with these jets, we detect a slower (≈c/2) and broader (up to 1 mm) ionization front consistent with collisional hot electron energy transport. 1999 © The American Physical Society.

Abstract:

We present the first results of fast electron deposition in a laser shock compressed plasma. The interaction of a 3 ps, 15 J laser pulse with solid polyethylene targets is used to produce fast electrons on one side of foil targets and a 2 ns duration laser pulse is used to drive a shock wave into the target from the opposite side. Kα emission from chlorine fluor buried layers is used to measure the electron transport. The hot electron range in the shock compressed plastic is found to be approximately twice as large as the range in the solid density plastic. © 1998 The American Physical Society.