I am trying to understand how energy is conserved in a magnetron. If the electrons are following a circular path in the magnetic field and never reach the anode will there be zero current between the anode and the cathode? If so how does the device consume power from the external circuit supplying the anode voltage? The electrons appear to be orbiting on at a constant potential in the electric field so how does the electric field impart energy to them? I think I am missing something fundamental about how this works, can anyone help? Thanks.