Question Solved1 Answer Subject : ELECTRICAL ENGINEERING EET 730 ASSIGNMENT 7.(a). A TWT operates under following parameters, , circuit Beam voltage Vo 3 kV, beam current lo = 30 mA, characteristics impedance of helix Zo 10 length, N = 50 and frequency f = 10 GHz, Determine, (iv) (v) (vi) Gain parameter Output power gain in db and all Four propagation constants. (5pts) (b). Explain how oscillations are suppressed in TWT. (2pts) (c). Derive the expression for axial for electric field in helix type travelling wave tube. (2pts) 3.(a). Compare the performance characteristics of TWT amplifier and magnetron. (2pts) (b). Derive the expression for axial for electric field in helix type travelling wave tube. (2pts) (c). Derive the equation for gain of TWT amplifier. (2pts)

(ii) Output Power GainThe output power gain of helix TWT is given by,{:[A_(P)=-9.54+47.3 NC],[=-9.54+47.3 xx50 xx2.92 xx10^(-2)],[:.Ap=59.52dB]:}(iii) The Four Propagation constant Y_(1),Y_(2),Y_(3) and Y_(4) are given by,Y_(1)=-beta_(e)c(sqrt3)/(2)+jbeta_(e)(1+c//2)Where,{:[beta_(e)=(omega)/(V_(0))=[(2pi xx10^(10))/(0.593 xx10^(6)sqrt(3xx10^(3)))]],[=>beta_(e)=1.93 xx10^(3)rad//m],[y_(1)=-1.93 xx10^(3)xx2.9 xx10^(-2)xx0.87],[+j 1.93 xx10^(3)[1+(2.9 xx10^(-2))/(2)]],[:.y_(1)=-49.03+j 1952],[y_(2)=beta_(e)((sqrt3)/(2)+jbeta_(e)(1+c//2):}],[=1.93 xx10^(3)xx2.9 xx10^(-2)+j 1.93 xx10^(3)(1+(2.9 xx10^(-2))/(2))],[:.y_(2)=-49.03+j 1958]:}Scanned withCamScannery_(3)=jB_(e)(1-C)=j 1.93 xx10^(3)(1-2.9 xx10^(2)):.y_(3)=j 1873.64{:[y_(4)=-jB_(e)(1-c^(3)//4)],[=j 1.93 xx10^(3)[1+((2.9 xx10^(-2))3)/(4)]],[:.Y_(4)=-j 1930]]:}Scanned withCamScannerAns: b. As the slow wave structure of travelling wave tube is bidirectional, the signal can propagate in both the directions. When output of the coupler reflects the Signal, it reflects backward along slow wave structure and serves as a feedback signal. This results oscillations in the travelling wave tube.In travelling wave tube, oscillations are produced due to bunching. The bunching is the process in which electrons in the beam travel with higher speed than the wave travelling on the wire and interact with travelling wave fields due to velocity modulation.In order to prevent oscillations in TWT, it is neressary to slow down the speed of bunches. This can be accomplished by transferring the electron energy to the travelling wave fields with correct polarity. This increases the samplitude the of travelling wave along the TWT axis. As a CamScannerresult, the speed of electrons decreases and they cannot travel faster than the wave travelling on wire. Thus, no bunching takes place and no oscillations are produced.The above drawback can be overcome by using a slow wave structure, which reduces the speed of travelling wave below speed of electrons in the beam.Scanned withCamScannerAns:C. An electron beam with convection current generates an electric field and combines it with the existing field in the slow wave circuit and combines it with the existing field in the slow wave circuit. Thus, the electric field increases the circuit power. The relation between the electron beam and the equivalent slow wave circuit is illustrated in the figure.FigureThe equivalent circuit includes the following parameters,i-Convection currentL - Inductance/lengthScanned withCamScannerC - Capacitance/lengthI-Altern ... See the full answer