Reduction of ion thermal diffusivity inside a magnetic island in JT-60U Tokamak plasma

A peaked ion temperature profile is observed inside the magnetic island during mode locking after the back transition from H mode to L mode in JT-60U. The thermal diffusivity evaluated inside the magnetic island is 0.1m2/s, which is much smaller than that outside the magnetic island by an order of magnitude. The present experiment gives clear evidence that ion heat transport inside a magnetic island can bifurcate and the transport level can be suppressed to the very low level associated with the strong flow shear at the boundary

Large Faraday rotation of resonant light in a cold atomic cloud

We experimentally studied the Faraday rotation of resonant light in an optically-thick cloud of laser-cooled rubidium atoms. Measurements yield a large Verdet constant in the range of 200 000 degrees/T/mm and a maximal polarization rotation of 150 degrees. A complete analysis of the polarization state of the transmitted light was necessary to account for the role of the probe laser's spectrum