Til bevillingsoversigt

Synthetic Phase Contrast Imaging Diagnostic for Turbulence Studies at Wendelstein 7-X

Carlsbergfondets internationaliseringsstipendier

What

The goal of the project is to study plasma turbulence at the Wendelstein 7-X fusion device, located at the Max Planck Institute for Plasma Physics (IPP) in Greifswald, Germany, as a postdoctoral associate on mission from MIT. Turbulence will be studied using the phase contrast imaging (PCI) diagnostic operated by MIT at Wendelstein 7-X.

Specifically, the project concerns the development of a synthetic PCI diagnostic, i.e., a code capable of reproducing the diagnostic signal that will be measured for particular plasma conditions. Such a synthetic diagnostic will improve the interpretation of the PCI turbulence measurements from previous experiments at Wendelstein 7-X and be of great use when planning and executing experiments in the steady-state operation phase, starting in 2021.

Why

The description of turbulence continues to present great experimental, numerical, and theoretical challenges in fluid mechanics and plasma physics. Plasma turbulence is of particular importance at astrophysical scales, e.g., when describing the dynamics of stars, the interstellar medium, and accretion disks of black holes, but also occurs in laboratory experiments, where it may be investigated and characterized in much more detail than what is possible for most space plasmas.

Additionally, laboratory scale plasma turbulence is the main phenomenon hampering the realization fusion power, which would provide a virtually inexhaustible, non-intermittent, carbon dioxide-free energy source, without the safety and waste issues of fission power.

How

The synthetic PCI diagnostic will be developed by extending the existing packages used at the DIII-D and Alcator C-Mod fusion devices to the more complex geometry of Wendelstein 7-X. This will involve coordination with the PCI group at MIT, as well as the groups performing gyrokinetic simulations of plasma turbulence in Wendelstein 7-X at IPP and elsewhere. A specific initial step will be to port the synthetic PCI diagnostic package used at DIII-D from IDL to Python.

Once the synthetic PCI diagnostic has been developed, it will be used to analyse plasma turbulence in the previous Wendelstein 7-X experimental campaigns and to prepare experiments for the upcoming steady-state campaign, starting in 2021.

SSR

The ability to compare experimental and theoretical predictions for the complex geometry of Wendelstein 7-X would aid the development of turbulence codes capable of handling rather general, e.g., astrophysical, conditions. Additionally, the implementation of a synthetic PCI diagnostic at Wendelstein 7-X would allow the technique to be applied to a significantly broader range of laboratory plasmas than what is possible at present, which may lead to a general improvement in the interpretation of PCI signals.

Finally, the possibility of creating plasmas where turbulence is significantly suppressed could make a fusion power plant feasible, potentially solving many of the energy-related problems facing humanity in the 21st century.