Directional Motion Of Dust Particles In A Plasma

Dusty plasma is composed of electrons,ions,neutral particles and dust particles which contain thousands of basic charges,and their motion is coupled with each other.Generally,dusty particles move randomly,and the energy they absorb from plasma through particle-particle and particle-wave interactions cannot be effectively collected and utilized.Rectifying the random motion of dust particles into directional motion is the key to solve this problem.The realization of particle rectification in random environment is a scientific and technical problem that people have been concerned about.When disturbed by external forces,Feynman ratchet can cause particle flow by asymmetric potential without net macroscopic force,which has aroused widespread interest in physics,chemistry and biology systems.Necessary condition for the realization of Feynman ratchet is symmetry breaking mechanisms.Different systems may have different symmetry breaking mechanisms.In this work,the Feynman ratchet model is extended to the field of dusty plasma for the first time,and the concept of dusty plasma ratchet is proposed.The directional movement of dust particles is realized in the plasma environment,which can be controlled by changing the control parameters.The physical mechanism of the directional movement of dust particles is revealed: the potential of the asymmetric ratchet and the collective effect of dust particles.In the third chapter,the plasma parameters in the vacuum chamber are obtained by using COMSOL simulation and are utilized to calculate the electric charge of particles,the balance height of dust particles,the electric potential energy of particles at the balance height.Therefore,the inversion process of particle flow observed in the experiment is explained quantitatively,and the clear physical image is given.Further,a detailed study on the potential energy of asymmetric ratchet: By changing the number of ratchet teeth to change the asymmetry of ratchet,it is found that under the same experimental conditions,with the increase of ratchet teeth,the angular velocity of particles first increases and then decreases,There is an optimal number of teeth to make the best rectification effect of dust particles,which is further verified by numerical simulation.The results of this work are of great significance to the collection and utilization of the scattered energy in plasma.