Laser-Ion Acceleration from Transparent Overdense Plasmas at the Texas Petawatt: The 14,000,000.28 $ project

  I Pomerantz [1]  ,  J Blakeney [1]  ,  G Dyer [1]  ,  L Fuller [1]  ,  E Gaul [1]  ,  DC Gautier [2]  ,  AR Meadows [1]  ,  BM Hegelich [1]  ,  T Ditmire [1]  
[1] The University of Texas, Austin, Texas 78712, USA
[2] Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA

A steady increase of on-target laser intensity with also increasing pulse contrast is leading to light-matter interactions of extreme laser fields with matter in new physics regimes. At the 1.3PW Texas Petawatt laser  (TPW) we have realized interactions in the transperent-overdense regime (TOR), which is reached by interacting a highly relativistic, ultra-high contrast laser pulse with a solid density ultrathin target. The extreme fields in the laser focus are turning the overdense, opaque target transparent to the laser by the relativistic mass increase of the electrons. Thus, the interaction becomes volumetric, increasing the energy coupling from laser to plasma.

Using “plasma mirrors”, a simple and cheap laser pulse cleaning technique, we demonstrated generation of over 60 MeV proton beams, and used these beams to generate over 109 neutrons per shot.

Following an extensive pulse cleaning campaign planned for the TPW, we expect proton and deuteron beam energies to scale over 150 MeV/amu. The shown results now approach or exceed the limits set by many applications from ICF diagnostics over ion fast ignition to medical physics.

I will discuss these experimental results and supporting measurements to elucidate the underlying physics, as well as the properties of table-top laser accelerated ions expected in the near future.