Wendelstein 7-X

The Wendelstein 7-X (W7-X) reactor is an experimental stellarator built in Greifswald, Germany, by the Max Planck Institute of Plasma Physics (IPP), and completed in October 2015. Its purpose is to advance stellarator technology (first conceived by Lyman Spitzer) and though this experimental reactor will not produce electricity, it is used to evaluate the main components of a future fusion power plant; it was developed based on the predecessor Wendelstein 7-AS experimental reactor. The Wendelstein 7-X (W7-X) reactor is an experimental stellarator built in Greifswald, Germany, by the Max Planck Institute of Plasma Physics (IPP), and completed in October 2015. Its purpose is to advance stellarator technology (first conceived by Lyman Spitzer) and though this experimental reactor will not produce electricity, it is used to evaluate the main components of a future fusion power plant; it was developed based on the predecessor Wendelstein 7-AS experimental reactor. As of 2015, the Wendelstein 7-X reactor is the largest stellarator device. It has been anticipated to achieve operations of up to approximately 30 minutes of continuous plasma discharge in 2021, thus demonstrating an essential feature of a future fusion power plant — continuous operation. The name of the project, referring to the mountain Wendelstein in Bavaria, was decided at the end of the 1950s, referencing the preceding project from Princeton University under the name Project Matterhorn. The research facility is an independent partner project with the University of Greifswald. The Wendelstein 7-X device is based on a five field-period Helias configuration. It is mainly a toroid, consisting of 50 non-planar and 20 planar superconducting magnetic coils, 3.5 m high, which induce a magnetic field that prevents the plasma from colliding with the reactor walls. The 50 non-planar coils are used for adjusting the magnetic field. It aims for a plasma density of 3×1020 particles per cubic metre, and a plasma temperature of 60–130 megakelvin (MK). The main components are the magnetic coils, cryostat, plasma vessel, divertor and heating systems. The coils (NbTi in aluminium) are arranged around a heat insulating cladding with a diameter of 16 meters, called the cryostat. A cooling device produces enough liquid helium to cool down the magnets and their enclosure (about 425 metric tons of 'cold mass') to superconductivity temperature (4 K). The coils will carry 12.8 kA current and create a field of up to 3 teslas. The plasma vessel, built of 20 parts, is on the inside, adjusted to the complex shape of the magnetic field. It has 254 ports (holes) for plasma heating and observation diagnostics. The whole plant is built of five near-identical modules, which were assembled in the experiment hall. The heating system includes 10 megawatts of microwaves for electron cyclotron resonance heating (ECRH) which can operate continuously, and can deliver 80 MJ in the operation phase 1.2. For operational phase 2 (OP-2), after completion of the full armor/water-cooling, up to 8 megawatts of neutral beam injection will also be available for 10 seconds,. An ion cyclotron resonance heating (ICRH) system will become available for physics operation in OP1.2.