Return current heating of plasma in a relativistic electron ring experiment

Plasma heating was observed in a relativistic electron ring experiment. The diamagnetic field was measured with small magnetic probes. From these measurements it was found that about 50% of the beam energy was transferred to the plasma. The plasma heating was found to be due to return current dissipation. The return current decay time calculated from the ion-acoustic turbulence is consistent with the observed net current rise times. The evolution of these fields showed that the use of a diamagnetic loop to measure the plasma temperature would be inadequate.