Anisotropic Electron Velocity Distribution Functions in E×B Penning Source*

In the study of E×B Penning sources, the interaction between ambipolar electric fields and applied magnetic fields is crucial for determining electron trajectories, leading to a complex drift mechanism. Traditionally, experimental evaluations of electron variables have assumed isotropic electron energy probability functions. However, due to the significant magnetization and drift motions experienced by electrons, this assumption is often invalid. These conditions suggest a shift from isotropic to anisotropic behavior, presenting a challenge to both theoretical models and experimental approaches. This research focuses on the anisotropic velocity distribution of electrons in E×B Penning sources with a cross-field configuration. A rotatable planar probe is employed to gather data on the electron velocity distribution function under various operational conditions within the E×B Penning source. By rotating the probe 360 degrees, we can systematically map the angular distribution of plasma parameters, correlating these measurements with changes in magnetic field strength. The experimental data allow for the quantification of the degree of electron anisotropy, offering insights into the behavior of electrons under these specific conditions.