Observation of megagauss-field topology changes due to magnetic reconnection in laser-produced plasmas

The spatial structure and temporal evolution of megagauss magnetic fields generated by interactions of up to 4 laser beams with matter were studied with an innovative, time-gated proton radiography method that produces images of unprecedented clarity because it uses an isotropic, truly monoenergetic backlighter (14.7-MeV protons from (DHe)-He-3 nuclear fusion reactions). Quantitative field maps reveal precisely and directly, for the first time, changes in the magnetic topology due to reconnection in a high-energy-density plasma (n(e)similar to 10(20)-10(22) cm(-3), T-e similar to 1 keV).