Analysis of ion beam extracted from reflex tetrode

A reflex tetrode is proposed to be made on the basis of a new idea that the plasma source is separated from the anode. It is shown that the ion beam is forced to move from the anode toward the virtual cathode in the reflex tetrode. The expressions are derived for the ion-beam current densities which are extracted from reflex tetrodes. Two types of tetrodes, one of which has the ion source and the other has the plasma source, are considered. The analyses are given for the three kinds of geometries; plane, cylindrical and spherical.