Transmission of charged particles through probe apertures in fusion plasma edge diagnostics

The transmission of ions through a slit aperture perpendicular to a magnetic field is investigated. The investigation is important for the evaluation of particle collection probe measurements in fusion experiments in cases where such apertures are used. Analytic expressions which can be used for the interpretation of results from such probe measurements are derived. These expressions imply that the aperture influence on the ion flux is significant, provided the thickness to width ratio of the slit is not small. It is also seen that the aperture influence could be utilized for ion energy determination. (orig.)