Title: Ultra-intense laser interactions with nanostructures: creating extreme plasma conditions and high energy particles with ultrafast lasers
The interaction of femtosecond laser pulses of relativistic intensity with high aspect ratio nanostructures provides a unique combination of nearly complete optical absorption and enhanced energy penetration into near-solid density targets, volumetrically heating matter to an ultra-high-energy-density regime encountered in the center of stars [1]. It also generates gigantic quasi-static electromagnetic fields that efficiently accelerate particles. Here I will present an overview of the physics and applications of these dense relativistic plasmas that can be created with pulses of relatively modest energy from lasers that can operate at high repetition rate. Nanowire array experiments produced near-solid density plasmas with extreme degree of ionization (eg. Au+72), converted ultrafast pulses of laser light into intense x-ray flashes with record efficiency, and accelerated ions to MeV energies driving micro-scale fusion reactions that generate flashes of quasi - monoenergetic fusion neutrons 500 times larger than those from flat solid targets. Neutrons with energy > 10 MeV were also produced by nuclear interactions of energetic deuteron/protons from CD2 nanowires arrays with selected converter targets. These plasmas serve as a platform for advancing the understanding matter at extreme conditions, and open a possible new pathway to laser-driven fusion energy.