Relativistic Laser Interactions with Deuterated Nanowire Arrays
Abstract
Arrays of aligned nanostructures are unique in that the vacant spaces surrounding the nanowires allow for the deep penetration of ultrafast optical laser pulse energy into near solid density material, where light is trapped and practically totally absorbed. Electrons ripped off from the nanowire surface by the large laser field are accelerated in the voids to relativistic energies. Collisions of these energetic electrons with the nanowires rapidly heats the material to extreme temperatures, causing the nanowires to explode. Ions are rapidly accelerated. The use of sufficiently short laser pulses allows for very efficient coupling of the pulse energy deep into the nanowire array, heating a large volume of near solid-density material to multi-keV temperatures. This new approach to volumetric heating opens access to the ultra-high energy density plasma regime using compact Joule-level lasers. We have very recently demonstrated that the intense irradiation of deuterated nanowires accelerates large number of deuterons to energies near the peak of the D-D fusion cross section, efficiently producing neutrons with compact high repetition rate lasers. In agreement with simulations, we have experimentally observed the generation of 3 MeV deuterons and 10 MeV protons from deuterated polyethylene (CD2) nanowire arrays irradiated with femtosecond laser pulses of 1 Joule-level energy at an intensity of 8 x 10^19 W/cm2. We have observed a 500-fold increase in the generation of 2.45 MeV D-D fusion respect to CD2 solid targets irradiated at the same conditions. The best shots produced ~2 x 10^6 neutrons/Joule, the highest neutron yield obtained to our knowledge with Joule-level laser pulses. We have also observed a strong supra-linear increase of the neutron yield with laser pulse energy, indicating very promising scaling.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 28, 2017
- Source ID
- FA95501710278
Entities
People
- Jorge G. Rocca
Organizations
- Air Force Office of Scientific Research
- Colorado State University
- United States Air Force