Speaker
Gregory Wallace
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P5.1049.pdf
High field side LHCD in DIII-D: physics demonstration of reactor
relevant current drive
G.M. Wallace , P.T. Bonoli , S. Shiraiwa , S.J. Wukitch , J. Doody , R. Leccacorvi , R.
1 1 1 1 1 1
Vieira , W. Helou , C. Holcomb , J. Ferron , R.I. Pinsker
1 2 3 4 4
1
MIT Plasma Science and Fusion Center, Cambridge, MA USA
2
CEA, IRFM, F-13108 St-Paul-Lez-Durance, France
3
Lawrence Livermore National Laboratory, Livermore, CA USA
4
General Atomics, La Jolla, CA USA
Calculations show that high field side (HFS) launch of lower hybrid range of frequencies
(LHRF) power represents an integrated solution that both improves core wave physics (high
current drive efficiency at proper location) and mitigates plasma material interaction
(PMI)/coupling issues [1] . To demonstrate the benefits associated with HFS LHCD (wave
coupling, propagation, absorption, and current drive efficiency), a conceptual HFS LHCD
system has been developed for DIII-D, which represents the first fully developed HFS LHRF
system design for an operating tokamak.
Using existing DIII-D discharges, we have identified high performance scenarios with
excellent wave penetration, single pass absorption and high off-axis current drive efficiency
(r/a~0.6-0.8, FWHM of r/a=0.2 and driven current up to ~0.21 MA/MW). The DIII-D
antenna design utilizes proven launching technology (slotted waveguide, multijunction)
while remaining within established power density limits. The performance of the antenna
was simulated by ALOHA [2] and 3D MFEM [3] and shows low reflected power for a range
of plasma conditions.
From an operational perspective, launcher placement on the HFS has potential issues:
reduction of inner wall gap and launcher material compatibility. The former was investigated
through a scan of the plasma-HFS wall gap. Little or no impact of these plasma shape changes
was found on discharge confinement or stability. Data on material compatibility from a
molybdenum/carbon mockup antenna installed on the HFS wall of DIII-D will be presented.
Work supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences, using
User Facility DIII-D, under Award Number DE-FC02-04ER54698 and by US DoE Contract No. DE-FC02-
01ER54648 under a Scientific Discovery through Advanced Computing Initiative.
[1] P.T. Bonoli et al, 26th FEC IAEA TH/5-1 (2016).
[2] J. Hillairet, et al, Fusion Engineering and Design 84, 953-955 (2009).
[3] S. Shiraiwa et al, EPJ Web of Conferences 157, 03048 (2017).
