Experimental observation of precursor solitons in a flowing complex plasma

TL;DR

This paper reports the first experimental observation of precursor solitons in a flowing dusty plasma, demonstrating their formation due to supersonic dust flow over an obstacle, with theoretical support from the forced Korteweg-deVries model.

Contribution

First experimental demonstration of precursor solitons in a flowing dusty plasma with theoretical analysis using the forced Korteweg-deVries equation.

Findings

Precursor solitons observed upstream of a moving object in plasma.

Wake structures of linear dust acoustic waves downstream.

Theoretical explanation based on the forced Korteweg-deVries model.

Abstract

The excitation of precursor solitons ahead of a rapidly moving object in a fluid, a spectacular phenomenon in hydrodynamics that has often been observed ahead of moving ships, has surprisingly not been investigated in plasmas where the fluid model holds good for low frequency excitations such as ion acoustic waves. In this paper we report the first experimental observation of precursor solitons in a flowing dusty plasma. The nonlinear solitary dust acoustic waves (DAWs) are excited by a supersonic mass flow of the dust particles over an electrostatic potential hill. In a frame where the fluid is stationary and the hill is moving the solitons propagate in the upstream direction as precursors while wake structures consisting of linear DAWs are seen to propagate in the downstream region. A theoretical explanation of these excitations based on the forced Korteweg-deVries model equation is provided and their practical implications in situations involving a charged object moving in a plasma are discussed.