A method is described for suppressing secondary electron emission from the negatively biased electrode of a beam direct energy converter by surrounding it with magnetic field lines. Experiments in a positive ion beam converter with a magnetically protected suppressor have shown that the secondary electrons generated by ion bombardment are successfully prevented from leaving the suppressor. It is also found that backscattered ions from the positive electrode occupy a noticeable portion of the loss currents generated in a converter with a copper electrode.