Theoretical Study On THR Evolution Of Void In Dusty Plasma

The void is a local dust-free region that spontaneously evolves in the early stage of the growth of dust particles in the dusty plasma,which has a clear boundary with the dusty cloud.At present,the research on the void mainly focuses on the circular void,and there is no detailed explanation for the generation mechanism of the ring void.In this paper,the evolution mechanism of two kinds of voids is discussed by numerical method.In the past,experiments have proven that the electron temperature in the void is lower than that in the dust cloud.Based on this point,the influence of the spatial distribution of the electron temperature on the void is studied by calculating the one-dimensional nonlinear model of cylindrical symmetry including convection term and explicit ionization,and the images of the circular void and the ring void are obtained by simulation.The results show that the threshold value of electron temperature is required for the formation of circular void.It is found that when the electron temperature is greater than the threshold value,a stable circular void is generated,and as the electron temperature increases,the time required for the circular void to reach a steady state decreases and its size decreases.This law is not affected by electron temperature spatial distribution set in the center.Combined with the studies of circular void,we speculate that the electron temperature in the ring void is also lower than that in the dust cloud.Through the assumption of the spatial distribution of electron temperature,the simulation results in a ring-shaped void.And the influence of the intensity of the spatial variation of the electron temperature on the ring void is verified.The results show that when the electron temperature change is severe enough,a ring void is generated.And as the intensity increases,the time required for the ring void to reach a steady state decreases,and the size increases slightly.Based on the simulation results of the electron temperature,it is speculated that the formation of the ring void is related to the collision of ion-neutral particles.The collision leads to the local dissipation of energy,which may lead to the decrease of the electron temperature.The simulation results also show that there is no ring void when the local collision in the space is relatively weak.With the aggravation of the collision degree somewhere in the space,a stable ring void can be produced when the threshold is exceeded,and the more severe the collision is,the shorter the time to produce the ring void is,and the faster the ring void reaches the stable state.The evolution trend is close to the simulation results of electron temperature,which verifies the correctness of the hypothesis.The simulation results are helpful to the qualitative explanation of the experimental phenomena.