Short pulse interaction experiments for fast ignitor applications

A detailed investigation of many aspects of the physics of laser-plasma int eraction at very high laser intensities is required in order to assess the feasibility and the promise of the fast ignitor scheme for inertial confine ment fusion. Relevant results, obtained in a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Centre d 'Etudes Atomique, Limeil Valenton (France), are presented and discussed her e. In particular, the formation of plasma channels was observed following t he propagation of relativistically intense, ps laser pulses through underde nse plasmas. The channels persist long after the interaction, and their exp ansion has been measured. Efficient guiding of ultraintense laser pulses, b oth through preformed density channels and through solid guides, has been d emonstrated. Finally, indication of collimated fast electron propagation th rough solid targets has been obtained from the observation of filamentary i onization tracks in laser irradiated solid targets.