Design and Numerical Analyses of the M4 Steering Mirrors for the ITER Electron Cyclotron Heating Upper Launcher

Four electron cyclotron heating upper launchers (ECHULs) will be used at ITER to counteract magnetohydrodynamic plasma instabilities by targeting them with up to 24 MW of mm-wave power at 170 GHz. This mm-wave power is injected through eight ex-vessel (EV) waveguide assemblies for each ECHUL to the in-vessel (IV) waveguides. The mm-wave power exiting the eight IV waveguides inside the ECHUL is reflected by three fixed mirror sets and finally aimed by two independent steering mirrors to specific plasma locations. These two steering mirrors have recently experienced an important redesign in order to deal with the new requirements. This article reports the status of the steering mirrors as well as the fluid dynamic and thermomechanical analyses carried out to validate the design for the normal operation (NO) scenario. The fluid dynamic analyses show that the power dissipated in both steering mirrors due to the mm-wave radiation, nuclear heating, and plasma heat flux can be properly removed with an acceptable mass flow generating admissible pressure drop, temperature rise, and corrosion rate values. The results obtained in the thermomechanical simulation, validated using the American Society of Mechanical Engineers (ASME) code, shows that the steering mirror design is capable of withstanding the expected loads taking place during NO.

Design status of the double Closure Plate Sub-Plate concept for the ITER Electron Cyclotron Upper Launcher

René Chavan, Timothy Goodman, Jean-Daniel Landis, Avelino Mas Sanchez, Florian Ramseyer, Matteo Vagnoni

The Closure Plate Sub-Plate (CPSP), which defines the border between ex-vessel and in-vessel components of the Electron Cyclotron Upper Launcher (EC UL), bundles the waveguides into a sub-assembly which can be manipulated separately from the UL Port Plug (PP). The primary CPSP functions are to provide transmission line feedthroughs, support and alignment of the attached waveguides, neutron and gamma shielding, and Tritium/vacuum containment. The double CPSP concept, which is divided into In-vessel Waveguides CPSP and Thermal Isolation CPSP, was recently introduced in order to minimize the openings that expose the interior of the plug, to avoid the near environment activation in case of maintenance or intervention on the in-vessel components. This paper reports the most recent status of the CPSP as well as the analyses carried out to validate the design for normal operation. The fluid-dynamic analyses show that the power dissipated due to mm-wave transmission can be properly removed with an acceptable mass flow producing admissible values of pressure drop and temperature rise in the cooling systems. The results obtained in the thermo-mechanical simulation, validated using the ASME code, shows that the CPSP design is capable of withstanding the expected loads taking place during normal operation.

2018

Fluid-dynamic and thermo-mechanical analyses of the Monoblock Mitre Bend for the ITER electron cyclotron Upper launcher

René Chavan, Timothy Goodman, Avelino Mas Sanchez

The ITER Electron Cyclotron Heating (ECH) system will be used to counteract magneto-hydrodynamic plasma instabilities by aiming up to 20 MW of mm-wave power at 170 GHz. The primary vacuum boundary at the Electron Cyclotron Upper Launcher (EC UL) extends into the port cell region through eight beamlines, defining the so-called First Confinement System (FCS). Each beamline, designed for the transmission of 1.31 MW, is delimited by the closure plate at the port plug back-end and by a diamond window in the port cell. The FCS essentially consists of a Z-shaped set of straight corrugated waveguides (WG) connected by Mitre Bends (MB) with a nominal inner diameter of 50 mm. Due to the space restrictions, the eight MBs at the last FCS section are grouped into two monoblocks. Each Monoblock Mitre Bend (MBMB) consists of a body with corrugated feedthroughs defining a specific angle for each beamline and four mirrors attached by bolted connection to reflect the mm-wave power. The thermal expansion arising from the ohmic losses, the cooling pressure, the bolt pre-tension and the imposed displacements coming from the connection with the transmission lines are the primary design loads for the MBMBs. The fluid-dynamic analyses performed for both upper and lower MBMBs show that highest temperature takes place in the MB mirrors, reaching a maximum value of 203 degrees C at the beam center. The thermomechanical analyses demonstrate that the peak stress also occurs at this location with a maximum value of 324 MPa. These stresses are categorized and compared with the allowable limits defined in the ASME code, what probes that the current design of both upper and lower MBMBs are able to withstand the loads taking place during the mm-wave normal operation.

ELSEVIER SCIENCE SA2021

Progress of the ECRH Upper Launcher design for ITER

René Chavan, Timothy Goodman, Jean-Daniel Landis, Emanuele Poli, Francisco Sanchez, Olivier Sauter

The design of the ITER ECRH system provides 20 MW millimeter wave power for central plasma heating and MHD stabilization. The system consists of an array of 24 gyrotrons with power supplies coupled to a set of transmission lines guiding the beams to the four upper and the equatorial launcher. The front steering upper launcher design described herein has passed successfully the preliminary design review, and it is presently in the final design stage. The launcher consists of a millimeter wave system and steering mechanism with neutron shielding integrated into an upper port plug with the plasma facing blanket shield module (in-vessel) and a set of ex-vessel waveguides connecting the launcher to the transmission lines. Part of the transmission lines are the ultra-low loss CVD torus diamond windows and a shutter valve, a miter bend section and the feedthroughs integrated in the plug closure plate. These components are connected by corrugated waveguides and form together the first confinement system (FCS). In-vessel, the millimeter-wave system includes a quasi-optical beam propagation system including four mirror sets and a front steering mirror. The millimeter wave system is integrated into a specifically optimized upper port plug providing structural stability to withstand plasma disruption force and the high heat load from the plasma side with a dedicated blanket shield module. A recent update in the ITER interface definition has resulted in the recession of the upper port plug first wall panels, which is now integrated into the design. Apart from the millimeter wave system the upper port plug houses also a set of shield blocks which provide neutron shielding. An overview of the actual ITER ECRH Upper Launcher is given together with some highlights of the design. (C) 2014 Elsevier B.V. All rights reserved.

Elsevier Science Sa2014

Progress of the ECRH Upper Launcher design for ITER

René Chavan, Timothy Goodman, Jean-Daniel Landis, Emanuele Poli, Francisco Sanchez, Olivier Sauter

Elsevier Science Sa2014