Multi-cm Long Magnetically Controlled Optical Plasma Channel

Experimental results from the Jupiter Laser Facility at the Lawrence Livermore National Laboratory which show multi-cm long plasma channels with minimum plasma densities below 5x10$^{17}$ cm$^{-3}$ are presented. These results are obtained using an external magnetic field ($<$5 Tesla) to limit the radial heat flux from a pre-forming laser beam. The resulting increased plasma pressure gradient produces a parabolic density gradient which is shown to be tunable by changing the external magnetic field strength. These results are compared with 3-D resistive MHD modeling. For these channel conditions, quasi-static kinetic simulations show that 90{\%} of the energy in a 150 TW short pulse beam is guided over 5 cm and predict electron energy gains of 3 GeV from Laser Wakefield Acceleration. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and was partially funded by the Laboratory Directed Research and Development Program under project tracking code 06-ERD-056.