Observation of Local Structures in Asymmetric Ion Sheath

Abstract

Local structures of the potentialand ion saturation current profile are found in an asymmetric ion sheathunder which the ion sheath instability is excited.In the high density region, the local structureof the ion saturation current profilewas observed near the sheath edge for the first time.The formation of the sheath structure is confirmedby the numerical simulation using the particle-in-cell code.In this simulation, it was observed thatthe space potential oscillates in the both two regionsdevided by the asymmetric ion sheathand, the potential swell like as the virtual anode oscillatenear the sheath edge in the driver region.It was concluded that the oscillation of the space potentialsand the ion bounce motion inside the sheathlead to excite and suppress the grid current fluctuationfrom these experimental and numerical results.