A study of the best electric arc heater regime for minimum copper cathode erosion is presented in this report. We take into account the dependence of the arc spot current density,
arc spot thermal volt-equivalent and arc velocity on magnetic field. We consider also the influence of the axial gas velocity on the erosion. We show that the minimum erosion value is attained only within a certain range of values of the magnetic field, temperature of the electrode surface and axial gas velocity.