On the Application of Small-Angle Electron Scattering to Plasma Diagnostics

摘要

The scattering of an electron beam injected into a plasma is described by Moliere's theory of multiple collisions. Such a theory has the unique advantages of including multiple as well as single scattering, being quantum mechanically correct from the outset, and of being independent of the exact form of the differential scattering law provided only that it goes over to the Rutherford law for large angles. It is also explained how plasma diagnostics can be performed with such a technique in any of three scattering regions chosen to cover all possibilities of operation. Unavoidable finite-dimension effects inherent in any laboratory application are analyzed and shown not to negate the attractiveness or utility of the method. The uniqueness of the present method lies in its use of small angle deflections to measure charged particle number density even in weakly ionized gases, as opposed to previous large angle methods useful for measuring the number of nuclei present regardless of the completeness of the atomic shells. (Author)