Study On TWT With Sheet Beam Rectangular-ring Loop Structure

Higher operating frequencies and larger output power are currently the main purposes for the development of traveling-wave tubes(TWTs).The traditional(circular)ring loop(RL)slow wave structures(SWSs)have higher interaction impedance than ring bar(RB)SWSs,which can effectively improve the interaction efficiency of TWTs.However,due to the relative complexity of the structure,the processing of RL SWSs is relatively cumbersome.At the same time,the output power of RL TWT also needs to be effectively improved in practical use.In view of this,a novel type of rectangular ring vertex semi-rectangular loop(RRVL)SWS is proposed.Based on the analysis of its high-frequency characteristics,beam wave interaction research based on pencil electron beam and sheet electron beam is carried out.The main work of this article is as follows:1.The study of the high-frequency characteristics based on a novel square ring vertex semi-rectangular loop(SRVL)is carried out.The influences of the dimension parameters on the high frequency characteristics of the SRVL SWS are studied in detail.The high frequency characteristics of the traditional RL SWS and the novel SRVL SWS are compared under the same size conditions.The calculation results show that,the novel SRVL SWS can provide higher fundamental wave interaction impedance under flatter dispersion conditions.2.The study of a SRVL TWT with pencil electron beam is carried out.Based on the optimization of S parameters,with the beam voltage of 12.8 k V and beam current of 0.4 A,the SRVL TWT can produce the maximum output power of 3136 W,corresponding to a small-signal gain of 51.95 d B and an electron efficiency of 30.63 %,respectively.Compared with the RL TWT under the same electrical parameters,the output power is increased by 16.41 %,a small-signal gain is increased by 0.66 d B,and an electron efficiency is increased by 4.32 %,respectively.3.The study of a RRVL TWT with sheet electron beam is carried out.The calculation results of high frequency characteristics show that,with increasing the ratio of the outer length to width of rectangular ring,The RRVL SWS can provide higher fundamental wave interaction impedance while maintaining a substantially consistent dispersion with the SRVL SWS.Based on the optimization of S parameters,with the beam voltage of 12.8 k V and beam current of 0.4 A,The calculation simulation results show that,a certain intensity of Back Ward-Wave oscillation will be caused with increasing the ratio of the outer length to width of the rectangular ring.Therefore,the Back Ward-wave oscillation is suppressed by arranging truncation and loading attenuators.After suppressing the Back Ward-wave oscillation,the RRVL TWT can produce the maximum output power of 3364 W,corresponding to an electron efficiency of 32.85 % and a small-signal gain of 52.26 d B,respectively.Finally,the beam wave interaction characteristics of the RRVL TWT are compared with that of the SRVL TWT.The calculation results show that,in the case of longer interaction periods,the RRVL TWT can provide higher output power,a small-signal gain and an electron efficiency.