In this paper, a scheme for bandwidth and gain enhancement of 0.220 THz traveling wave tube amplifier (TWTA) is presented. A two-section staggered double vane (SDV) slow wave structure (SWS) loaded with two period Bragg reflector at both the ends is analyzed in this paper. The attenuator section that separates the input and output section comprises of a six pitch long rectangular waveguide loaded with lossy material on top and bottom walls. Velocity taper is provided at all transitions for improved impedance match. The dispersion characteristics were computed through Eigen mode analysis in Microwave studio module of Computer Simulation Technology (CST) and the results were validated using Ansys's High Frequency Software Simulator (HFSS). 15dB transmission and reflection loss across a bandwidth of 45 GHz from 0.205-0.250 THz is provided by the design optimized attenuator while separating the input and output sections. Through particle in cell (PIC) simulations in CST Particle studio, beam wave interaction between input RF signal and a sheet electron beam is studied. The proposed TWTA yields 22dB gain across the bandwidth of 32 GHz ranging from 0.218-0.250 THz range for a beam current of 30 mA fed at an operating voltage of 19kV. © 2019 IEEE.