An energy supply unit for a traveling wave tube is configured to transform a first voltage present at a low voltage interface into a second voltage providable at a high voltage interface. The second voltage is greater than the first voltage and corresponds to a required operating voltage of the traveling wave tube. The energy supply unit is configured to receive a signal pattern via a signal input interface and to output a control signal via a control interface to the traveling wave tube for operating the traveling wave tube based on the signal pattern and to gradually and/or iteratively align or adapt the control signal to the signal pattern being present at the signal input interface when changing an operating mode of the traveling wave tube. A power draw at the beginning of the switched-on state may increase slowly and voltage drops at the high voltage supply may be minimized.