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PPPL contributions to the W7-X experimental program

Author: Samuel A Lazerson
Requested Type: Poster Only
Submitted: 2014-06-12 15:00:08

Co-authors: N. Pablant, D. Gates, H. Neilson, J. Lore

Contact Info:
Princeton Plasma Physics Laboratory
C-Site T140B, PO BOX 451
Princeton, New Jersey   08543
United States

Abstract Text:
The W7-X stellarator provides a unique experiment in which to understand the behavior of 3D fields in an optimized device. PPPL involvement in the project focuses on the development of perturbative trim coils, error field analysis, x-ray imaging of plasmas, 3D equilibrium reconstruction, and development of divertor control scenarios. A large set of window pane trim coils have been installed on the W7-X device allowing for error field studies. These coils provide a robust means to modify the edge divertor island structure and trim out low n error fields. A unique feature of stellarators is the existence of vacuum flux surfaces, allowing for field line tracing experiments to measure error field effects. Mapping experiments will focus on both intrinsic error field and those generated by the trim coils. An X-ray imaging crystal spectrometer will be installed at W7-X allowing for the measurement of ion temperature, electron temperature, and poloidal flow velocities. The XICS system features 5ms time and 2cm spatial resolution with coverage from the core out to a rho of ~0.8. Three-dimensional equilibrium reconstruction capabilities for W7-X are being developed. A forward modeling of the flux loops, segmented Rogowski coils, and Thomson scattering system has been performed. This is utilized to simulate a reconstruction with the STELLOPT code. The ability to measure the effect of error fields on divertor structure, trim out the effects, accurately measure the plasma profiles, and fit equilibria to those measurements allows for the development of divertor control scenarios. Simulations of strike point motion using field line diffusion are presented.

Characterization: 3.0

Comments:

Workshop on Exploratory Topics in Plasma and Fusion Research (EPR) and US-Japan Compact Torus (CT) Workshop
August 5-8, 2014
Madison, Wisconsin

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