Najmudin Z, Tatarakis M, Pukhov A, Clark E L, Clarke R J, Dangor A E, Faure J, Malka V, Neely D, Santala M I, Krushelnick K
Imperial College of Science, Technology & Medicine, Prince Consort Road, London SW7 2BZ, United Kingdom.
Phys Rev Lett. 2001 Nov 19;87(21):215004. doi: 10.1103/PhysRevLett.87.215004. Epub 2001 Nov 5.
Magnetic fields in excess of 7 MG have been measured with high spatial and temporal precision during interactions of a circularly polarized laser pulse with an underdense helium plasma at intensities up to 1x10(19) W cm(-2). The fields, while of the form expected from the inverse Faraday effect for a cold plasma, are much larger than expected, and have a duration approaching that of the high intensity laser pulse ( <3 psec). These observations can be explained by particle-in-cell simulations in 3D. The simulations show that the magnetic field is generated by fast electrons which spiral around the axis of the channel created by the laser field.
