Design and Performance of Microwave Components for ECH and ECE Applications at General Atomics

Abstract

This paper provides an overview of high power components for the application of Electron Cyclotron Heating transmission lines, and broadband devices for Electron Cyclotron Emission detection systems. The unique fabrication and assembly challenges are discussed, particularly in the context of ITER. The ITER ECH system will require robust, vacuum-compatible components such as polarizers, dummy loads, and switches that are sufficiently cooled to withstand 1 MW for 3,600 seconds. These elements, along with overmoded corrugated waveguide, are necessary to form transmission lines with efficiencies of 90%, and 90% transmitted HE11 mode purity. Recent high power test results are summarized and scaled from the 63.5 mm internal diameter design to the 50 mm diameter version that will be used for ITER. Elements designed for Electron Cyclotron Emission detection and reflectometry systems are discussed, such as frequency filters and polarization rotators. The large frequency operating range of corrugated waveguide is exploited for such applications. The application of additive manufacturing technology towards both low and high power components is considered as a promising new area of development.

High power mm-wave loss measurements of ITER ex-vessel waveguide components at the FALCON test facility at the Swiss Plasma Center

“…A GYCOM gyrotron occupies the second tower and its MOU is connected to a similar TL that starts at a similar height as the EU TL, then zig-zags down to 0.81m off of the false floor via 3 MBs to bypass the support tower of the TED gyrotron, and after ≈2.2m bifurcates in an RF switch (180°, or 90°bend) graciously provided by GA. The 90°b ranch of the switch has been used to test a GA RF load [22]. The through branch (180°) connects to a downtaper from 63.5mm to 50mm inner diameter.…”

Progress on performance tests of ITER gyrotrons and design of dual-frequency gyrotrons for ITER staged operation plan

“…A new MOU having a 50 mm-diameter waveguide interface adapter was designed and manufactured by QST. As part of FAT, an integrated test using ITER-relevant waveguide components (50 mm in diameter) [15] and the newly designed MOU was carried out. Figure 2(b) shows the layout of the transmission-line test-stand.…”

System of Electron Cyclotron Heating at the TRT Tokamak

“…To transport the microwave radiation from gyrotron to the tokamak discharge chamber, it is proposed to use a vacuum-tight transmission line (Fig. 5) based on the oversized cylindrical waveguide with corrugated inner surface [14][15][16]. The radiation of the gyro- tron is formed by a MOU and it is supplied to the entrance of the waveguide transmission line as a wave whose structure is close to the eigen НЕ 11 wave of the waveguide.…”