Effect of finite Larmor radius on the performance of electrostatic energy analyzer

A method for estimating the effect of magnetic field on the measurements of the electrostatic energy analyzer is described. The exact effect of the finite Larmor radius rL, relative to the analyzer grid mesh radius rm, i.e. the ratio α (α=rL/rm), has been investigated. The ratio α defines a critical limit at which the analyzer data starts to be blur. Magnitude of errors γ in the measured velocity and energy distribution functions and the collector current are computed as a function of magnetic field and for stationary and flowing plasmas. Critical values of particle energy Uc, velocity vc and of magnetic field Bc for both electrons and ions, in a wide range of rm are determined. The method of analysis is useful for any plasma regardless of the type of the distribution function. (author)