Space‐Charge Waves in Crossed Electric and Magnetic Fields

摘要

The problem of space‐charge waves propagating along a neutralized electron stream moving in a medium pervaded by crossed static electric and magnetic fields is discussed. From energy considerations it is shown that gain can be realized either by conversion of the electron kinetic or potential energy into electromagnetic energy. A small signal analysis shows that for the first case the TE and TM modes are coupled in general. However, when the electron velocity is much smaller than the velocity of light the coupling coefficients are negligible and the gain realized is identical with that of the conventional traveling‐wave tube. A similar analysis for the second case, which is that of the traveling‐wave magnetron tube, yields the interesting result that the TE and TM modes separate even when the electron velocity is comparable with the velocity of light.