TRAVELING-WAVE TUBE DEVICES WITH NONLINEAR DIELECTRIC ELEMENTS

The performance of traveling-wave tube (TWT) amplifiers incorporating nonlinear dielectric elements is studied via computer simulation. Two different situations are investigated: 1) the use of nonlinear dielect ric elements to reduce intermodulation distortion and 2) the use of vo ltage controlled dielectrics to provide rapid modification of the disp ersion characteristics of the slow-wave structure. In the first case, the use of dielectrics with negative second-order susceptibilities is studied as a means of reducing phase and intermodulation distortion, U se of these dielectrics along with dynamic velocity taper to reduce am plitude modulation distortion results in marked reduction of predicted intermodulation distortion. In the second case, the goal is to design an amplifying structure whose gain as a function of frequency can be varied electrically. Preliminary design studies show that relatively l arge changes in the center frequency of the amplification band can be achieved with relatively modest changes in the dielectric constant of helix support structure.