Hägermann, MoritzMoritzHägermannBirtel, PhilipPhilipBirtelMeyne, SaschaSaschaMeyneSafi, DjamschidDjamschidSafiJacob, ArneArneJacob2019-04-252019-04-252018-06IEEE Transactions on Electron Devices 6 (65): 2236-2242 (2018-06)http://hdl.handle.net/11420/2461Two magnetic field tapering concepts for the suppression of backward-wave oscillations in helix traveling-wave tubes (TWTs) are presented. Therefore, the beam-wave interaction in a homogeneous helix section is modified. Increasing the field strength reduces the beam diameter and consequently the beam-wave coupling, while an additional offset in the focusing field alters the synchronism between both. The theoretical background is introduced and results from a 1-D small-signal and a 3-D particle-in-cell code are presented and compared. Furthermore, a concept to apply the suppression techniques to a complete TWT is presented, and the influence on the amplifier output characteristics is analyzed.en0018-93832018622362242Journal Article10.1109/TED.2018.2810501Other