Wendelstein 7-X at the Greifswald branch of IPP is a large stellarator with modular superconducting coils which enable steady state plasma operation in order to explore the reactor relevance of this concept.
WISP gauges (Thierry Kremeyer/Jessica Hoffman)
The WISP gauge project is an ongoing collaboration between UW Madison and the Max-Plank Institute. The Wisconsin In Situ Penning (WISP) gauge has been developed and successfully implemented at the Max-Plank Institute for Plasma Physics in Greifswald, Germany, within the Wendelstein 7-X (W7X) Stellarator.
With the goal of advancing research for efficient, clean fusion energy, W7X is a multinational endeavor and the largest steady-state fusion energy experiment of its kind. The contribution to W7X from the WISP gauge project comes from the capacity to measure impurities within the neutral reservoir space.
A WISP gauge itself is a miniaturized Penning gauge arrangement, which exploits the ambient magnetic field of magnetic confinement fusion experiments to establish the Penning discharge. Through these discharges, impurities can be detected, thus allowing adjustments to avoid radiative energy loss and fuel dilution. The employability of the WISP gauge extends beyond W7X, and is also applicable to other Stellarators, as well as other fusion energy devices, such as Tokamaks.
Helium Beam Diagnostic (Erik Flom)
Two copies of a thermal helium beam diagnostic have been installed and operated on Wendelstein 7-X in stellarator-symmetric locations. These have been used to measure density and temperature profiles in the device’s scrape-off layer, including the plasma within its novel island divertor setup. These profiles provide important experimental measurements of temperature and density gradients, which in turn reveal the energy and particle transport behavior in the device. This in turn allows for validation of computer modeling results and for the development of global models to link edge and core plasmas. These diagnostics are ideally situated to explore transport effects arising from the slight changes in the 3D boundary of W7-X caused by divertor control coils and changes in the overall device rotational transform.