03pA04
LHDにおける共鳴磁場摂動による大振幅ELM制御実験結果のトカマクとの比較検討
Comparison Study of ELM Control Results by Resonant Magnetic Perturbations
in LHD Plasmas with Those in Tokamaks
東井和夫、鈴木康浩、大舘 暁、田中謙治、榊原 悟、成嶋吉朗、LHD実験グループ
K. Toi, Y. Suzuki, S. Ohdachi, K. Tanaka, S. Sakakibara, Y. Narushima, LHD Experiment Group
核融合研
NIFS

W (kJ)

w/o RMP(MW)

w/o RMPw/ RMPP

tottotp

w/ RMPew/o RMPw/ RMPGas puff rate
w/o RMP w/ RMP

H (a.u.)

w/ RMPGas puff rate (a.u.)

e<n >(1019-3m )H (a.u.)

w/o RMPZ(m)eiceiptc

H (w/o RMP) #111514
H (w/ RMP) #111522

width is r/a~0.1(a: averaged minor plasma radius).
The ETB is destroyed by each large ELM in thecase without RMPs. In the case with RMPs, theETB is partially destroyed by mitigated ELMs.
MHD equilibrium was calculated by the HINT2
code [6] in order to infer how much radial extent
RMPs penetrate into plasma edge region and affectmagnetic field structure there. Figure 2 shows thecalculated Poincare plot of field lines and radial
profile of the connection length in the H-mode withRMPs. The ETB indicated by shaded zones near
the edge is in stochastic field region (SFR). This
result that ETB is(a) Rax=3.9m, < >=0.5% (HINT2) w/ RMP
inSFR
is
0.6
0.4
consistent
with
0.2
0
the experiment,-0.2
because applied
-0.4
-0.6
RMPs obviously
2.5
3
3.5
4
4.5
5R(m)
modifythe(b)
61000
L5
pressure profile in100410
the ETB region.
312
Note that as seen
0.1
100.01
44.2
4.4
4.6
4.8
from Fig.2 SFRR (m)and island chain Fig.2 (a)Poincare plot of thezone
expands plasma with RMPs calculated
furtherinterior by HINT2 code, (b)profiles ofbeyond the ETB the calculated connection
region (R<4.5m). length and /2 together withThis is caused by electron mean free path.
Pfirsh-Schlüter
current in 3D plasma with large field period number
N=10. The existence of such extended SFR is notclarified experimentally yet, so far. In this talk,details of ELM mitigation on LHD are presentedand the differences and similarities to the results intokamaks will be discussed.
[1]T.E. Evans et al., Phys. Rev. Lett. 92 (2004)
235003 and Nature Phys. 2 (2006) 419.
[2]Y. Liang et al., Phys. Rev. Lett. 98(2007) 265004.
[3]W. Suttrop et al., Phys. Rev. Lett. 106 (2011)
225004.
[4]K. Toi et al., 24th IAEA FEC 2013, San Diego andsubmitted to Nucl. Fusion.
[5]P.B. Snyder et al., Phys. Plasmas 12 (2005) 056115.
[6]Y. Suzuki et al.,Nucl. Fusion 46 (2006) L19.
L ,  (m)In D-T burning plasmas having high pedestal
temperature, suppression or mitigation of edge
localized modes (ELMs) is required for machinesafety and good plasma performance. Various
ELM control techniques are being developed inmany tokamaks. In particular, 3D magnetic field
perturbations (MPs) applied externally cansuccessfully suppress or mitigates large amplitude
ELMs[1-3]. The results are interpreted that field
stochastization in the pedestal region by the MPs
would control ELMs. However, the mechanisms
are still unclear. Study of 3D MP effects on ELMs
in helical plasmas may give us insights into theunderstanding. Recently, large amplitude ELMs
were clearly mitigated by application of resonant
magnetic perturbations (RMPs) on LHD [4]. The
ELMs on LHD are thought to be induced byresistive interchange modes (RICs), instead of
peeling/ballooning modes in tokamak H-modes[5].
InFig.1,
discharge behavior
W(a)
60
with
m=1/n=1
40
10
RMP application isP
20
5compared with that00
withoutRMPs,80(b)60
where ELMs are7040
induced by RICs
50
destabilized at the30
rational
surface
42.8<n >(d)3.52.4
3
/2 =1 near the2
2.5
1.6
2
1.2
footofedge
1.5
0.8
1
0.4
0.5
transport
barrier00
3.8
4
4.2 4.4 4.6 4.8(ETB).
RMPstime(s)clearly
mitigate Fig.1 Discharge behaviors with
impacts of ELMs, and without RMPs, where thethat is, the relative plasma stored energy Wp, total
drop of stored absorbed power Ptot, Hemission,line
averagedenergy Wp/Wp iselectron density <ne> and gas
reducedfrom puff rate are shown.
~20% down to~5% or less, having an increased ELM repetition
frequency by more than a factor of 5. The ETB is
most prominent in density profile but is not clear inelectron and ion temperature profiles. The ETB