Superintense laser pulses interacting with dense matter may drive extremely large currents of high energy electrons which, in turn, generate strong quasi-static magnetic fields. Such magnetized relativistic plasmas have interest for the study of exotic astrophysical processes on a laboratory scale.
By using an ultrafast proton beam technique an international research team has measured with high spatial and temporal resolution toroidal magnetic fields generated by electrons refluxing at both surfaces of a solid target (“fountain effect”) interacting with the high-power VULCAN laser beam at Rutherford Appleton Laboratory, UK. Magnetic field values up to 50 Megagauss have been estimated, implying that they play a role in the dynamics of the laser-generated plasma and in particular in the process of ion acceleration. Two CNR/INO scientists (C. A. Cecchetti and L. A. Gizzi) have participated to the experiment and the theorical interpretation has been supported by a simple model developed by another CNR/INO scientist (A. Macchi): see the preprint http://arxiv.org/abs/1202.0389 .
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