Numerical simulation studies of a turbulent heating experiment

Electrostatic, one-dimensional, numerical plasma simulations have been used to study results from the University of Saskatchewan turbulent heating experiment. In a simulation plasma with an initial sinusoidal density perturbation (approximating the effect of a bumpy magnetic field parallel to the plasma current in the experiment), the application of a constant external-electric field can cause the electrons to split into two groups, one freely accelerating and the other trapped near zero velocity in a potential well resulting from the inhomogeneous ion density. The ensuing electron-electron instability can cause reduced acceleration and heating of the electrons, even when the ions are infinitely massive. This process appears to have a role in the experiment although close quantitative agreement cannot be claimed. A common and important feature of the simulations was the tendency of all observed instabilities to heat the electrons at a rate which maintained the ratio of electron drift to thermal velocity near unity. This heating rate has been observed in the experiment.