Sheared <i><b>E</b></i> × <i><b>B</b></i> flow encountered in space plasma excited from two controllable methods

Abstract

Sheared <i> <b>E</b> </i> × <i> <b>B</b> </i> flow has been frequently observed to excite instability in space plasma. In this study, two methods – the interpenetrating plasma and ring electrode methods – were developed in the Keda Space Plasma EXperiment (KSPEX) device to trigger sheared <i> <b>E</b> </i> × <i> <b>B</b> </i> flow. Both methods produce sheared <i> <b>E</b> </i> × <i> <b>B</b> </i> flow by generating a radial electric field. The results of the experiment indicated that plasma instabilities in the ion cyclotron range can be excited by these methods. Therefore, the methods reported here are important for research on the mechanism for generating sheared flow-driven plasma instabilities, which may enrich our understanding of geospace physics.