Study On Sheath Stability For Dielectric Wall In Hall Thruster

Hall Thruster is the most mature and most widely used electrical propulsion device and develops in the direction of high efficiency, high specific impulse, long life and small plume divergence angle. The teams of research all over the world focus on improving and optimizing the performances of Hall Thruster, China also has been focusing on the application of power thrust. Sheath as the foundational physical problem becomes the focus and population of research currently because it makes important influences on heat fluxes onto the wall, ion streaming, near-wall electron conductivity, wall erosion and plasma state in the channel and so on.When collide with the channel wall, electrons can knock out secondary electrons, which is the so called SEE phenomenon. SEE plays a very important role in the operation of the device and influences the sheath especially. This paper has given a deep look to the relation between plasma and sheath, established the boundary condition of sheath. And also studied the relation between sheath and wall deeply, i.e. SEE phenomenon. reviewed the existed SEE Model, summarized the modeling method of SEE Model, then, we introduced a new SEE Model, which is in accord with dielectric material's SEE characteristic, and this new SEE Model has better numerical characteristic in sheath calculation.There is literature consider that the cause of near wall sheath's oscillation is the near wall SEE. We studied the effect orderliness of SEE yield and SE spectrum to sheath stationary.In this paper, we revealed electric particles'flowing orderliness, gave a determinant criterion about Classical sheath's existence condition, we can obtain Classical sheath's stationary potential whit this criterion theoretically, and the potential by analysis has good accordance with the numerical solution.As a fundamental physical problem, plasma sheath greatly influences the complex physical phenomenon in the channel, however it is very difficult to investigate it by experiments, so we introduce a one-dimensional kinetic model of the sheath, and the boundary condition on the wall position is the SEE model. Based on one-dimensional kinetic sheath model, we have taken a look to the sheath characteristic in Hall Thruster channel with the three different SEE Model.In the channel of Hall Thruster, electrons do not obey the Maxwellian distribution. We constructed a distribution function to indicate the real electron distribution character and analyzed the influence on sheath.