Transport Dynamics Characteristics Of Dusty Plasma In Two Typical Environments

Dusty plasma is a complex plasma system composed of electrons,ions,neutral molecules and charged dust particles,which exists widely in space,laboratory and semiconductor processing industry.Charged dust particles can introduce new electric potential structures and a slow time scale into the plasma system,which affects the transport characteristics of the plasma,resulting in lots of complex structures and dynamic processes that are not found in ordinary plasma.Many special physical phenomena in dusty plasma are related to the transpo rt process.Studying the transport characteristics of dusty plasma is the key to explain these physical phenomena and understand the physical characteristics of dusty plasma.Although much theoretical and experimental research on the transport characteristics of dusty plasma has been carried out,the understanding of some transport dynamics processes of dusty plasma is still limited,especially the transport dynamics process of dust particles with variable mass.In view of this,based on traditional plasma fluid model,relevant transport theory is investageted and a transport dynamics model of dusty plasma is established in this dissertation.The transport dynamics characteristics of charged particles and related impact factors in two typical dusty plasma environments,gas discharge and the mesopause region,are emphatically studied.The main research contents are as follows:Firstly,a physical model of dusty plasma transport dynamics is established based on traditional plasma fluid model.Considering the collision between plasma and dust particles,the influence of charged dust particles on transport coefficients of electrons and ions in these two typical dusty plasma environments,gas discharge and polar mesopause is computed.Also,the effects of charged dust particles on plasma ambipolar diffusion equations and diffusion velocity are studied on the time scale of ion motion.A multipolar diffusion model including charged dust particles is established on the time scale of dust particle motion,and the role of gravity in particle diffusion is discussed.Then,based on the dusty plasma transport dynamics model above,a dusty plasma fluid model for gas discharge is established.The electron energy conservation equation is introduced to describe the evolution pr ocess of electron temperature.The model is numerically solved by the plasma module of COMSOL multi-physics software.The influence of charged dust particles on DC glow discharge plasma transport is investigated.The effects of charged dust particles on density distribution of each kind of charged particles,flow density of electrons and ions,electric field and electron temperature are analyzed.By introducing transport equations of dust particles into the above gas discharge plasma fluid model,the transport process of charged dust particles in DC glow discharge plasma is studied,and the self-consistent solution of the transport dynamics process of dust particles and plasma is realized.Distribution of dust particle and plasma parameters in the discharge tube under different conditions is studied by changing the discharge current and dust particle radius.At last,the transport dynamics characteristics of ice particles and plasma in the polar summer mesopause region are studied.Based on the motion equatio n of a variable mass object,a transport dynamics model of ice particles is established to study the transport process and density distribution of ice particles.With the obtained ice particle density structures,the transport process and density distribution of electrons and ions are studied based on the dusty plasma diffusion model.A discrete charging model is introduced into the diffusion model to describe the dynamic charging process of ice particles.The effect of external environmental factors such as neutral wind velocity,water vapor density and altitude on the density structures of ice particles,electrons and ions is discussed.The results lay a theoretical foundation for understanding the formation mechanism of polar mesosphere summer echoes phenomenon.