Study of Electron Transport across a Magnetic Filter

Electron transport across a magnetic filter is studied by the 2-dimensional particle simulation. It is found that low energy electrons diffuse much faster than high energy electrons. Dominant electron diffusion mechanism is found to be ExB-drift where E is the thermally excited low frequency electrostatic fluctuation field and B is the filter magnetic field. Because high energy electrons have large Larmor radii, those particles are immobile by ExB-drift by averaging out short wavelength fluctuations (Finite Larmor radius effect). Large gradient B drift of high energy electrons can also contribute to smooth out the effect of small scale fluctuations. Electrostatic fluctuation spectrum around the lower hybrid frequency is observed experimentally. Electron diffusion in the experiment may be dominated by these fluctuations.