Measurements and correction of the 1/1 error field in Wendelstein 7-X

Bozhenkov, S. A.; Otte, M.; Biedermann, C.; Jakubowski, M.; Lazerson, S. A.; Sunn Pedersen, T.; Wolf, R. C.

doi:10.1088/1741-4326/aaf20c

Measurements and correction of the 1/1 error field in Wendelstein 7-X

Journal Article · Wed Dec 19 00:00:00 EST 2018 · Nuclear Fusion

DOI:https://doi.org/10.1088/1741-4326/aaf20c· OSTI ID:1512870

^[1]; Otte, M. ^[1]; Biedermann, C. ^[1]; Jakubowski, M. ^[1]; ^[2]; Sunn Pedersen, T. ^[1]; ^[1]

Max-Planck-Inst. für Plasmaphysik, Greifswald (Germany)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

In this paper, vacuum flux surface mapping is used to measure the error field in Wendelstein 7-X. Two methods for discriminating the perturbation from other co-resonant modes are applied: measurements of the helical axis shift in a magnetic configuration with the rotational transform barely above one on the axis; and measurements of the edge island structure with cancellation of intrinsic islands by divertor control coils. The normalized radial amplitude in Boozer coordinates is found to be about in the first case and about in the second one, with the discrepancy being attributable to different currents in the planar coils. The error field can be reliably compensated by using error field trim coils with currents about 100 A. Here, this compensation also helps to identify the error field of about . During plasma operation in divertor configurations, it is confirmed that the present field leads to asymmetries in the power distribution and that the compensation improves this symmetry.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: European Commission; USDOE

Contributing Organization:: W7-X Team

Grant/Contract Number:: AC02-09CH11466

OSTI ID:: 1512870

Alternate ID(s):: OSTI ID: 22929618

Journal Information:: Nuclear Fusion, Journal Name: Nuclear Fusion Journal Issue: 2 Vol. 59; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Performance of Wendelstein 7-X stellarator plasmas during the first divertor operation phase Wolf, R. C.; Alonso, A.; Äkäslompolo, S. Physics of Plasmas, Vol. 26, Issue 8 https://doi.org/10.1063/1.5098761	journal	August 2019
Coherence imaging spectroscopy at Wendelstein 7-X for impurity flow measurements Perseo, Valeria; Gradic, Dorothea; König, Ralf Review of Scientific Instruments, Vol. 91, Issue 1 https://doi.org/10.1063/1.5126098	journal	January 2020
Drift effects on W7-X divertor heat and particle fluxes Hammond, K. C.; Gao, Y.; Jakubowski, M. Plasma Physics and Controlled Fusion, Vol. 61, Issue 12 https://doi.org/10.1088/1361-6587/ab4825	journal	October 2019
First demonstration of radiative power exhaust with impurity seeding in the island divertor at Wendelstein 7-X Effenberg, F.; Brezinsek, S.; Feng, Y. Nuclear Fusion, Vol. 59, Issue 10 https://doi.org/10.1088/1741-4326/ab32c4	journal	August 2019
Experimental characterization of a quasi-coherent turbulent structure in the edge plasma in Wendelstein 7-X Han, X.; Krämer-Flecken, A.; Windisch, T. Nuclear Fusion, Vol. 60, Issue 1 https://doi.org/10.1088/1741-4326/ab4e75	journal	October 2019

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