Measuring E and B fields in laser-produced plasmas with monoenergetic proton radiography.

Electromagnetic (E/B) fields generated by the interaction with plasmas of long-pulse, low-intensity laser beams relevant to inertial confinement fusion have been measured for the first time using novel monoenergetic proton radiography methods. High-resolution, time-gated radiography images of a plastic foil driven by a 10(14) W/cm(2) laser implied B fields of approximately 0.5 MG and E fields of approximately 1.5 x 10(8) V/m. Simulations of these experiments with LASNEX+LSP have been performed and are in overall (though not exact) agreement with the data both for field strengths and for spatial distributions; this is the first direct experimental test of the laser-generated B-field package in LASNEX. The experiments also demonstrated that laser phase plates substantially reduce medium-scale chaotic field structure.