Measurements on nonlinear space-charge waves

Results of measurements on the nonlinear ac currents in a velocity modulated confined electron beam are reported. The test vehicle is a two cavity klystron type device with an axially movable demodulator. The ac beam currents at the fundamental and at the two lowest harmonic frequencies have been measured as functions of the distance along the beam for various modulation levels and dc beam currents. The work provides experimental data in the transition range between linear space-charge wave-type and ballistic-type behavior of the ac beam current. The experimental results are in good agreement with the nonlinear space-charge wave theory.