Speaker
Olaf Neubauer
(Forschungszentrum Jülich GmbH)
Description
The mission of Wendelstein 7-X is to assess the reactor capabilities of the HELIAS stellarator line. W7-X is equipped with superconducting coils (B=2.5 T) and is sufficiently large (V=30 m33) to potentially attain steady-state plasmas at low collisionalities and high densities at the same time. As prerequisite for long-pulse operation, W7-X will employ high power, cw microwave heating (initially >5MW) along with NBI and ICRH. The first operation phase (OP1.1) started late 2015 with five uncooled inboard limiter stripes made of graphite. This very first campaign will be followed by a one year operation phase OP1.2 from 2017 onward, following the exchange of the limiters by 10 uncooled 3D divertor modules, shape-wise exactly mimicking the actively cooled, steady-state-capable high heat flux divertor which will be installed for operation phase 2 (OP2), starting in ~2020.
The first campaign OP1.1 allowed commissioning and demonstration of the overall device operation, i.e. its primary aim was the demonstration of the proper functioning of the control and safety systems of all main device components, like vacuum system, cryogenics, magnetic field coils, ECRH heating and their interplay. Furthermore, this phase was used for putting into operation a significant fraction of the complete set of diagnostics for the divertor operation phase OP1.2 and for experimentally demonstrating the existence of nested flux surfaces.
Assuming the heat loads can be spread out evenly between the limiters, 1 second discharges at 2 MW of heating power could be run in OP1.1. The expected plasma parameters are sufficient to demonstrate the readiness of the installed diagnostics and even to run a first physics program, albeit restricted to relatively short pulses, and limiter configurations.
The diagnostics available for this first operation phase, including some special limiter diagnostics, and their capabilities will be presented. This will include engineering challenges in view of steady-state stellarator operation (long pulse operation, provision of machine safety, stray-radiation hardening, and 3D mechanical engineering). First experiences with the operation of the diagnostics will also be addressed. Furthermore, a survey on physics-requirement driven engineering developments (e.g. divertor manipulator) for future campaigns (OP2 and beyond) will be given.
This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
Co-authors
Dag Hathiramani
(Max Planck Institut für Plasmaphysik, 17491 Greifswald, Germany)
Gabor Kocsis
(Wigner RCP, Budapest, Hungary)
Michael Endler
(Max Planck Institut für Plasmaphysik, 17491 Greifswald, Germany)
Monika Kubkowska
(IPPLM, Warsaw, Poland)
Olaf Neubauer
(Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, 52425 Jülich, Germany)
Ralf Konig
(Max Planck Institut für Plasmaphysik, 17491 Greifswald, Germany)
Teresa Estrada
(CIEMAT, Madrid, Spain)
for the W7-X Team
(Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung - Plasmaphysik, 52425 Jülich, Germany;Max Planck Institut für Plasmaphysik, 17491 Greifswald, Germany;CIEMAT, Madrid, Spain;IPPLM, Warsaw, Poland;Wigner RCP, Budapest, Hungary;Princeton Plasma Physics Laboratory, Princeton, NJ, United States;IST, Lisbon, Portugal;CEA, Cadarache, France;PTB, Braunschweig, Germany;Los Alamos Nat’l Lab, NM, United States;Oak Ridge Nat’l Lab, TN, United States;Consorzio RFX, Padova, Italy;ENEA, Frascati, Italy;Innsbruck University, Innsbruck, Austria;ERM Brussels, Brussels, Belgium;Institute of Atomic and Subatomic Physics, Vienna University of Technology, Vienna, Austria;Aalto University, Helsinki, Finland;University of Seville, Seville, Spain;Technical University of Eindhoven, Eindhoven, Netherlands;Cagliari University, Cagliari, Italy;University of Wisconsin, Madison, WI, United States;National Institute for Fusion Science, Toki, Japan)
