Speaker
Emilia R. Solano
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P4.1044.pdf
Using rotating current ribbons to model MHD: the EHO
Emilia R. Solano1, K. Burrell2, T. Strait2, T. Evans2, S. Haskey3, T. Osborne2, X. Chen2,
B. S. Victor4, C. P. von Thun5,6, DIII-D team# and JET Contributors*
EUROfusion Consortium, JET, Culham Science Centre, Abingdon, OX14 3DB, UK.
1
Laboratorio Nacional de Fusión, CIEMAT, Madrid, Spain; 2General Atomics, San Diego,
California 92186-5608, USA;3Princeton Plasma Physics Laboratory, Princeton, New Jersey
08543-0451,U.S.A.;4Lawrence Livermore National Laboratory, Livermore, California
94550, USA; 5Forschungszentrum Jülich GmbH, Institut für Energie- und Klimaforschung -
Plasmaphysik, 52425 Jülich, Germany; 6EUROfusion PMU, Culham Science Centre,
Abingdon, United Kingdom.
From the earliest studies of MHD modes [1] it was assumed that field aligned current
distributions might be responsible for the magnetic fluctuations observed, but now analysis is
typically carried out in terms of mode numbers n (toroidal) and m (poloidal) of the measured
magnetic field fluctuations, taking into account toroidicity [2,3] and plasma shape [4] as
corrections on an effective poloidal angle.
Here we present a model of the MHD instability based on Mirnov’s initial assumption, now
taking into account the plasma shape. We assume there is ribbon of current parallel to the
magnetic field at a rational surface in the plasma. We reconstruct the plasma equilibrium with
kinetic constraints, trace candidate rational field lines with the TRIP3D code [5], and
compute the field from a unit current along a field line spinning past each of the Mirnov
probes, matching the frequency of the observed modes and their n number. The comparison
of the amplitude and shape of the synthetic signals with measured dB/dt informs us of the
accuracy of the reconstructed equilibrium, the width of the ribbon, and the applicability of
this model to the mode observed. Mode frequency is matched against measurements of the
main ion rotation profile, to obtain mode location and compare with the q profile. This
procedure can be used to model solitary modes, such as the Outer Mode in JET [6], and
possibly some EHOs in DIII-D [7]. The preliminary results obtained so far are promising
when compared to [8].
This material is based upon work supported by the Department of Energy under Award
Number DE-FC02-04ER54698.
[1] S.V. Mirnov, I.B. Semenov, Soviet Atomic Energy Vol.30, 1, 22 (1971); [2] V.G. Merezhkin,
Sov. J. Plasma Phys. 4, 152 (1978); [3] O. Klüber et al., Nucl. Fus. 31 907 (1991); [4] D. Testa et al.,
Rev. Sci. Inst. 74, 1694 (2003); [5] T.E. Evans et al., Phys. Plasmas 9, 4957 (2002); [6] E.R. Solano et
al., Phys. Rev. Lett. 104, 185003 (2010) [7] K. H. Burrell et al., Physics of Plasmas 8, 2153 (2001);
[8] E J Strait, Rev. Sci. Inst. 77, 023502 (2006)
# See the author list of “W.M. Solomon 2017 Nucl. Fusion 57 102018”
* See the author list of “X. Litaudon et al 2017 Nucl. Fusion 57 102001″
