Design of the Transmission Lines for 140 GHz ECRH System on HL-2A

Abstract

A new 140 GHz/2 MW/3 s electron cyclotron resonance heating (ECRH) system composed of two units is now being constructed on HL-2A. As a part of the system, two transmission lines marked No.7 & 8 play the role of carrying microwave power from two gyrotrons to the tokamak port. Based on the oversized circular corrugated waveguide technology, an evacuated transmission system with high power capability and high transmission efficiency is designed. Details are presented for the design of the corrugated waveguide, the layout of the proposed lines and the vacuum pumping system. Then mode conversion losses due to coupling, misalignment, bends and gaps are discussed to serve as a reference for analyzing the transmission efficiency and alignment. Finally, a dual-modes propagation case consisting of the HE11 and LP11 even modes is discussed

Investigation on the multi-hole directional coupler for power measurement of the J-TEXT ECRH system

“…H 1x and E 1y are normalized electromagnetic field components of the dominant LP 01 mode in the primary waveguide, which can be calculated as equations (7) [6,20].…”