Local measurement of nonclassical ion heating during magnetic reconnection

Local ion temperature and flows are measured directly in the well-characterized reconnection layer of a laboratory plasma. The measurements indicate strongly that ions are heated due to reconnection and that more than half of the reconnected field energy is converted to ion thermal energy. Neither classical viscous damping of the observed sub-Alfvénic ion flows nor classical energy exchange with electrons is sufficient to account for the ion heating, suggesting the importance of nonclassical dissipation mechanisms in the reconnection layer.