DESIGN STUDIES OF 170 GHz, 0.5-1.5 MW CW GYRO TR ON FOR PLASMA HEATING

Abstract

Energy for next generation is crucial issue due to limited availability of fossil fuel. Fusion energy comes up with potential and clean energy source for next decades. Fusion reactions require plasma environment at very high temperature of 10-15 x 106 Celsius. To achieve such a high temperature different plasma heating system is used simultaneously. Electron Cyclotron Resonance Heating (ECRH) is one of the effective heating methods which requires high frequency (28 - 170 GHz), high power (0.5 - 4 MW) continues wave (CW) RF-source. Gyro-oscillators (Gyrotrons) fulfills all requirement of ECRH source and highly accepted by plasma science community. This thesis includes design of gyrotron for thermonuclear fusion reactor. Along with ECRH system Gyrotron is also used extensively for plasma diagnostics, Material Processing, Deep-space Radar etc. as a source of RF-wave with different frequency and power level. In present work, conceptual design of 170 GHz CW gyrotron with power level of 0.5 MW for Indian Tokamak and with power level of 1.5 MW for International Thermonuclear Experimental Reactor (ITER) Tokamak are stated. Using mode selection and mode competition procedure various modes are examined and best mode is chosen with consideration of various physical parameters and starting cur-rent plots. TE24,6 and TE36,10 mode are chosen for 0.5 MW and 1.5 MW respectively. Triode type MIG is designed and optimized using ESRAY codes. Both Gyrotrons are designed with conventional cavity gyrotron which includes interaction section with weak input and output taper sections. Magnetic guidance system which consist of super-conducing magnets provide necessary magnetic field at the place of interaction. By changing physical dimension, number of turn and position of coil desired magnetic field profile is achieved. Output system of gyrotron consist of non-linear taper followed by Quasi-optical launcher and RF-window. Performance and reliability of gyrotron are checked by single mode and multi mode self consistence calculation in form of output power and efficiency. v Output of 600 KW power is achieved with efficiency of nearly 35 % with TE24,6 and low wall loss while more than 1500 KW power is achieved with same efficiency using TE36,10 mode. Results of RF-behavior justified reliability and feasibility of both the Gyrotron. Various software packages are used to design different part, like Gyrotron Design Suit V. 01 (GDS V. 01), Gyrotron Cavity Interaction Calculation and Launcher Optimization Tool (LOT) and Surf3D for quasi-optical design.