The axially controlled magnetron: A new type of magnetron, controlled by current through the filament

In vacuum tubes with straight filaments of large diameter, it is found that the magnetic field of the heating current exercises a restraining effect on the escape of electrons, equivalent to the action of the grid in the pliotron, or the impressed magnetic field in the magnetron. This new valve principle may be utilized to control the output of the tube for practical purposes, such as changing high-voltage direct current into alternating current; and leads to a very simple and efficient type of tube.