Importance of magnetic resistive fields in the heating of a micro-cone target irradiated by a high intensity laser

Obtaining keV ion temperatures at solid density, i.e. “warm dense matter”, in the laboratory would be of great interest to measure opacity and equations of state of matter under extremes conditions. Here we report a new means to effectively confine the energetic electrons and localize the energy deposition to a small, more uniformly heated, volume at the tip of nanofabricated micro-cone targets. This is achieved with very high contrast laser irradiation, which interacts with the cone wall to generate strong (~10 MG) localized resistive magnetic fields within the target bulk. Temperatures of up to ~200 eV are observed, with an input laser energy of 10 J. This new means has been investigated both experimentally and with Particle-In-Cell simulations.