J. Plasma Fusion Res. SERIES, Vol. 8 (2009)

Overview on Turbulence and Structure Formation during
Resonant Magnetic Perturbations at TEXTOR
Andreas Krämer-Flecken1) , Yuhong Xu2) , Sergey Soldatov1,3) , Marcin Jakubowski1,4) Yungfeng
Liang1) , Dirk Reiser1) and Oliver Schmitz1)
1)

Institute for Energy Research – Plasma Physics, Forschungszentrum Jülich, Association EURATOM-FZJ,
Trilateral Euregio Cluster, Germany, www.fz-juelich.de/ief/ief-42)Ecole Royale Militaire / Koninklijke Militaire School, Euratom-Belgian State Association,
Trilateral Euregio Cluster, Avenue de la Renaissance 30, B-1000 Brussels, Belgium
3)
Nuclear Fusion Institute, RRC Kurchatov Institute, 123182, Moscow, Russian Federation
4)
Max-Planck-Institute for Plasma Physics, EURATOM-IPP Association, Greifswald, Germany(Received: 29 August 2008 / Accepted: 15 December 2008)

Resonant magnetic perturbations (RMPs) are discussed in ELM mitigation scenarios at diﬀerent
devices and envisaged for future devices as ITER. In parallel extensive eﬀorts have been performed tomeasure and understand the interaction between turbulence and RMPs.
At TEXTOR poloidal cross correlation reﬂectometry, Mirnov coils and Langmuir probes are available
to observe turbulent aspects during RMP operation. This paper will present an overview on diﬀerent
aspects of turbulence during application of RMPs. The presented investigations concentrate on (i) the
reduction of the poloiodal connection length due to formation of ergodic layers by the RMP on thegeodesic acoustic mode at the plasma edge; (ii) the description of structures in RMP generated island
chains and especially on the observation of ﬂow patterns inside the island; (iii) the enhanced turbulent
transport in the pump out scenario at TEXTOR and (iv) the eﬀect of the RMP on the blobby transport
at the plasma edge.
Keywords: Turbulent transport, resonant magnetic perturbation, geodesic acoustic mode, island structure, blobby transport
R = 1.77 [m], I

1. Introductiona42

During the last years extensive eﬀorts have been
performed to measure the turbulence characteristics
and understand the interaction with resonant magnetic perturbations (RMPs). Turbulence and turbulent structures are the key for a better understandingof transport properties and a starting point for better control of particle– and energy transport with theaim to improve the plasma scenarios for future devices as ITER. As it was recently demonstrated at
JET, the ELM activity can be mitigated by application of RMPs [1]. However, a deeper understanding of
the interaction of RMPs with the plasma turbulenceis needed.
At TEXTOR the tools to investigate the plasma –RMP interaction are available. To generate RMPs
the dynamic ergodic divertor (DED) [2] is used. The
large variety of diﬀerent operation (3/1, 6/2 and 12/4)
conﬁgurations allows to modify the magnetic topology
at the plasma edge by varying the current in the perturbation coils, its frequency and the pulse shape. On
the other hand TEXTOR is equipped with a set of
diﬀerent fast sampled and high resolution diagnostics,
as poloidal correlation reﬂectometry (CR), reciprocating Langmuir probes and Mirnov coils. Those diagnostics have been successfully used in the study ofDED= 3 [kA], βpol= 0.2540

ρ [cm]

38
36

6/2
5/2

34
32
30
80

90

100
110
120
poloidal angle θ [deg]

130

140

Fig. 1 Poincaré plot obtained for a vacuum calculation
and a superimposed ohmic plasma with qa = 4.5.
The island chains of m/n = 5/2 and m/n = 6/2
are clearly visible.

zonal ﬂows and GAMs [3], turbulence transport andblobby transport [4]. Since diﬀerent plasma quantities are measured by these diagnostics, the correlation
between them can yield additional information on theorigin of turbulence itself.
In section 2 the DED and the diﬀerent diagnostic tools
are described. After a short overview on macroscopic
eﬀects and supposed structure formation at the edgein section 3, the inﬂuence of the RMP on the geodesic

author’s e-mail: a.kraemer-ﬂecken@fz-juelich.de44©2009 by The Japan Society of Plasma
Science and Nuclear Fusion Research

A. Krämer-Flecken et al., Overview on Turbulence and Structure Formation during Resonant Magnetic Perturbations at TEXTOR

acoustic mode (GAM) is presented in section 4. Section 5 presents aspects of the structure in a RMP generated island chain. In section 6 the enhanced turbulent transport in the pump out scenario is discussed
followed by section 7 on the blobby transport. Section 8 summarizes the observations and discusses theconsequences for future applications of RMPs.

chains, Poincaré plots are of help. In Fig. 1 the magnetic structure at the position of the CR system for aplasma with ﬁxed βpol and IDED is shown. The open
circles indicate the positions of the CR cutoﬀ layer for
diﬀerent probing frequencies, which are close to the
RMP generated m/n = 5/2 island. Furthermore the

2. Diagnostic Tools at TEXTORTEXTOR (Ro = 1.75 m, a = 0.46 m) a limiter tokamak with circular poloidal cross section isequipped with a dynamic ergodic divertor[2] to generate RMPs. It consists of a set of 16 coils wrappedhelically around the high ﬁeld side of the vessel. The
main resonances of the generated RMP can be set tom/n = 3/1, 6/2 and 12/4. All here reported experiments are performed in the 6/2 conﬁguration withdc DED operation and varying DED current. Due tothe RMP the plasma at the edge is not longer symmetrical in φ– and θ–direction, where φ and θ denotethe toroidal and poloidal angle, respectively. Due tothe applied RMP the nested ﬂux surfaces at the edge
become disturbed. Two diﬀerent regions can be identiﬁed using the Kolmogorov length Lk in braided magnetic ﬁelds [5] as a measure. As long as the poloidal
connection length (Lc ) is less than the Kolmogorov
length, the region is called laminar. If Lc � Lk the region is called ergodic. The transition between laminarzone and ergodic layer takes place for nc ≈ 3−4, wherenc denotes the number of poloidal turns. In practicethe laminar zone has a slab size of Δ r ≈ 2 cm depending on the plasma parameters and the DED current.
A 4–channel correlation CR system [6] is available
which measures density ﬂuctuations and the perpendicular plasma rotation at two poloidal positions (θ =0o , 90o ) with an array of 5 antennae at each position.
It is further used to determine the turbulence decorrelation time and mean turbulence wavelength frompoloidal distribution of the cross correlation coeﬃcient. A set of Mirnov coils, Δφ = 135o toroidally
apart from the CR system, measures magnetic ﬂuctuations at θ = 0o , 30o , 45o , 60o , 75o , 90o , 270o and 330o .
For the observation of the plasma potential and theion saturation current at the plasma boundary multi–
array Langmuir probes are installed on a fast reciprocating manipulator [7]. It allows the measurement oflocal electron temperature (Te ) and density (ne ) andthe determination of the radial electric ﬁeld (Er ) fromthe ﬂoating potential (φf ).

Fig. 2 Comparison of radial proﬁles from Langmuir probes
for plasmas with RMP (IDED = 6 kA) and without
RMP: (a) Te ; (b) ne ; (c) pe and (d) Er .

5/2 island marks the region between open ﬂux surfaces(ergodic layer) outside the island and intact surfaces
more deep in the plasma.
Due to the short connection length to the target in
the laminar region (r ≥ 0.44 m) the turbulent spectrum changes. Coherent structures are reduced due toopen ﬁeld lines. The electron temperature (Te ) showsa signiﬁcant reduction by a factor 2 (see Fig. 2a). In
the ergodic region the decrease in Te is much less pronounced compared to the laminar zone. The gradientsin electron density (ne ) and plasma pressure (pe ) become more steep in the laminar zone (see Fig. 2c,d).
The higher mobility of the electrons compared to theions in this region of open ﬁeld lines causes a fasterloss of electrons and increases the ﬂoating potential
φf , measured by probes. From two radial diﬀerent
measurements of φf the radial electric ﬁeld Er is calculated. In Fig. 2d the comparison of Er with andwithout RMP is shown. Note that the maximum in
Er is shifted from the position of the last closed ﬂux
surface in a discharge without RMP to the position
where the transition from the laminar to ergodic zone
takes place. More deep in the plasma Er decreases
again. The change Er is also obtained from the measurements of the perpendicular plasma velocity (v⊥ )by the CR system

3. General aspects of RMPs at TEXTOR

Eﬀects of the DED on the plasma are recently
presented in [8, 9]. For the knowledge of the positionof island chains in 3-dim geometry and the relative
position of the diagnostic with respect to the island

Er = −(v⊥ − vdia ) · Bt
45(1)

A. Krämer-Flecken et al., Overview on Turbulence and Structure Formation during Resonant Magnetic Perturbations at TEXTOR

0kA
1kA
2kA
3kA
4kA
5kA
6kA

v⊥ / km/s

3.5

5/2 Island

3

0.07

2.5
2
1.5
0.34

f=19.8kHz
f=15.5kHz.

0.06

δΦGAM/δΦtot

4

0.05
0.04
0.03
0.02

0.36

0.38
r/m

0.4

0.01
−2

0.42

0

2

I

DED

Fig. 3 Proﬁles of v⊥ for ohmic plasma at diﬀerent IDED
generating the RMP.

4

/ kA

6

8

Fig. 4 Development of the relative phase ﬂuctuations
δΦGAM /δΦtot for two frequencies with increasing
RMP. Each frequency belongs to a diﬀerent radius:(i) f = 19.8 kHz; 0.345 ≤ r ≤ 0.350 m and (ii)f = 15.5 kHz; 0.380 ≤ r ≤ 0.385 m.

where vdia is the diamagnetic drift velocity. Furthermore the RMP has a large impact on the plasma rotation. The braking of the plasma by the RMP is seenin Fig. 3, where radial proﬁles of v⊥ are shown fordiﬀerent IDED . A reduction of a factor 2, comparedto the non DED case is observed in the ergodic zone
for the highest IDED current. Comparing the data for
IDED = 3 kA with the Poincaré plot in Fig. 1, a clear
correlation between the hump in v⊥ at r = 0.375 m
and the position of the m/n = 5/2 island is seen for2 ≤ IDED ≤ 4 kA. The 5/2 island width obtained
from the calculations is indicated in Fig. 3 by a double arrow. The observed hump in v⊥ can be related tothe outer separatrix of the 5/2 island. Poincaré plotsat IDED 4 kA show a stronger ergodization which leads
to the disappearance of the hump.

the RMP on the plasma increases and the GAM disappears at the plasma edge, however, at r = 0.34m a
peak at f = 19.8 kHz is still visible for IDED = 6 kA.
The measured frequency agrees with the expected
GAM frequency. The phase ﬂuctuations measured by
the CR system are proportional to the density ﬂuctuations [13]. Fig. 4 shows the relative GAM induced
phase ﬂuctuation (δΦGAM /δΦtot ) for two diﬀerent frequencies. The frequencies belong to diﬀerent radial
positions. For f = 15.5 kHz, δΦGAM /δΦtot decreases
with IDED . However, for f = 19.8 kHz which corresponds to 0.345 ≤ r ≤ 0.350 m an increase in theamplitude is observed. This is the radial region where
the m/n = 5/2 is assumed (see Fig. 1). A further
test of the long distance correlation by measuring simultaneously with top and midplane antennae shows
no correlation at the frequency at the innermost radius. This is an indication that the observed peakis not a GAM. A critical test for the GAM is thesimultaneous measurement of GAM induced density
ﬂuctuations and the related velocity oscillations. It
stems from the fact that an increase in the density
ﬂuctuation is related to an increase in the potential
ﬂuctuations [11, 12]:

4. GAMs and RMP
Geodesic acoustic modes modulate or even suppress the ambient turbulence by means of zonal ﬂows.
The additional shearing of the rotation velocity [10]can act as a trigger mechanism to improved conﬁnement. GAMs are predominately visible at the plasmaedge where the eﬀect of RMP is large. They show up
in frequency spectra of diﬀerent diagnostics as a single sharp line in the frequency range 10 ≤ fGAM ≤25 kHz. The frequency is a function of the local electron (Te ) and ion temperature (Ti ). A further signature of GAMs is the long distance correlation e.g. formeasurements with Δθ ≥ 90 o .
In several experiments the inﬂuence of RMPs on
GAMs is studied. In these experiments the scalingof the GAM frequency with local temperature, thepoloidal distribution, the density ﬂuctuations and thevelocity oscillations are investigated. Therefore the
DED current is increased on a shot to shot basis by
Δ IDED = 1 kA. For each pulse the CR system scansa radial range of 0.34 ≤ r ≤ 0.41 m using the top
antennae array. With increasing IDED , the eﬀect ofδ nGAMeδφGAM
∼
nc
Te

(2)

Here δ nGAM /nc denote the GAM induced relative
density ﬂuctuations, φGAM the potential ﬂuctuations,
Te the electron temperature and e the electron charge.
Since Te does not change, an increase of δ nGAM /nc
is related to an increase in φGAM which implies anincrease in the Ẽ × B velocity oscillations. Since thereﬂection layer is ﬁxed, any oscillation in ṽE× B willshow up in the measured ﬂuctuation of the propagation time (δ t) measured between two antennae. In
Fig. 5 the phase ﬂuctuation (a) and the related oscil-46

A. Krämer-Flecken et al., Overview on Turbulence and Structure Formation during Resonant Magnetic Perturbations at TEXTOR

lations in the δ t (b) are shown for r = 0.347 m fora case without RMP and a case with IDED = 4 kA.
For the phase ﬂuctuations a clear increase with DED
is seen but no increase in the velocity oscillations isvisible. The phase ﬂuctuations are not driven by the�r as it could be expected from the inﬂuence of theE
RMP on Er . This indicates that the observed line at
the GAM frequency is not a GAM.
In the stochastic region the decrease of the GAMs canbe understood from the comparison of the poloidal
connection length to the target and the distance traveled by particles within the time of a GAM oscillation. The GAM period at TEXTOR is in the orderof 50 ≤ TGAM ≤ 70 μs. For thermal electrons at a
local temperature of 100 ≤ Te ≤ 300 eV the propagation distance lp = vth · TGAM within TGAM yields
420 m to 500 m, where vth denotes the thermal velocity. This has to be compared with the Lc = nc q2π R0 ,where nc is shown color coded in Fig. 6 and q denotes
the local safety factor. With 330 ≤ Lc ≤ 400m for
12 ≤ nc ≤ 14, Lc < lp and therefore GAM oscillations are not possible.
The disappearance of the GAMs is also seen in thefrequency spectrum of probe measurements [7], where
an exponential decrease in the frequency range f ≤50 kHz is observed for IDED = 6 kA.

Fig. 6 The color coded poloidal turns nc to reach the target. Black circles denote the poloidal position of
the cutoﬀ layer of the CR-system.

5/2 island. The CR-system covers the transition fromthe ergodic zone to the inner plasma where Lc → ∞.
At the outer separatrix a frequency of 19.8 kHz is ob46
44

r [cm]

42

5. Structures in RMP generated Islands
As mention in section 4 the observed peak at afrequency close to the GAM frequency shows not theGAM properties. For several discharges with qa = 3.7
and IDED = 6 kA this line is investigated in detail.
From a Poincaré plot (see Fig. 7), where the radial positions of the reﬂection layer for the probing frequencyof the CR system are included, it can be seen thatthe estimation of v⊥ is close to the separatrix of the

32
0

b

Φ / a.u.

0.15
0.1
0

5

10

15

20

Frequency / kHz25100θ [deg]150

served. Increasing the probing frequency a further line
at 23.2 kHz shows up. At the innermost position themeasurement is already outside the island and bothlines have disappeared. However, the ion temperature
gradient driven quasi coherent mode is observed in thecoherence spectrum which is a further indication thatthe measurement is already outside the 5/2 island. In
the island itself a constant density is assumed, so thatthe measurement showing both lines is representative
for the whole island width (indicated by the double arrow across the island), due to the reduction in radialresolution of the CR-system. The observations are inagreement with a poloidal ﬂow inside the island [14].
From the observed frequency gap detected by the CR
system and the assumption of a closed ﬂow in the island, it will be once in the direction of the plasma
perpendicular rotation (Ω⊥ ) and once antiparallel.

0kA
4kA

0.2

50

Fig. 7 Poincaré Plot with reﬂection layer of the CR system
for IDED = 6 kA. The red arrow indicates the radial elongation of the reﬂection layer. Black arrows
indicate the rotation direction in the island.

0kA
4kA

fGAM

5/2

34

2

0
0.25

δt / a.u.

a

38
36

r=0.347m
4

5/2

40

30

Fig. 5 Phase (Φ) and δ t spectrum for IDED = 4 kA. The
increase in the Φ spectrum is seen clearly whereas
no eﬀect in the δ t spectrum is seen. The black
dashed lines indicate the background level for thereference case47

A. Krämer-Flecken et al., Overview on Turbulence and Structure Formation during Resonant Magnetic Perturbations at TEXTOR

From the CR-system Ω⊥ is deduced for the ambient plasma (without the 19.8 kHz line) and yields
Ω⊥ = 10.1 krad/s. This corresponds to a measured
frequency diﬀerence of 10.1/π = 3.2 kHz, which is exactly the diﬀerence between the two frequency bands.
Since the 23.2 kHz line is observed more deep in theplasma the ﬂow inside the island and the plasma rotation must be parallel. For the the 19.8 kHz line
plasma rotation and ﬂow in the island are antiparallel(see also the arrows in Fig. 7).
Rotating magnetic ﬂuctuations, connected with theisland structure, are detectable by Mirnov coils. The
60

Specgram of Coil Pi030 #105760

Frequency / kHz

50

Critical I

DED

40

23.2kHz

Frequency / kHz

20
10
0
−10

19.8kHz

−20
−30
−40
0

1

2

Time / s3

4

Fig. 9 Cross correlation between antennae B on top and
Mirnov coil at 30o . Note that the 23.2 kHz line ismore inside located than the 19.8 kHz line.

5

frequency gap

40of the ﬂow inside the island is ion diamagnetic drift(idd) direction. The diﬀerent poloidal rotation directions are also seen in Fig. 9, where the color coded
coherence for -19.8 kHz line is dominating (edd direction) compared to the 19.8 kHz line. The 23.2 kHz line
(idd direction) is more pronounced than the -23.2 kHz
line. Furthermore looking at the cross phase between
two antennae at the 19.8 kHz line a strong deviationfrom the ambient rotation is found which indicates noor only small perpendicular rotation. This is in agreement with a set of closed surfaces in the island, as
expected in a developed island.

IDED /

30

kA

f=23.2kHz20

f=19.8kHz

100
0Radial step of 1cm

30

6
for

#105817: B−Pi030

01

2Time / s3

4

5

Fig. 8 Spectogram of a Mirnov coil at 30o . Overlaid is the
DED current. For IDED ≥ 5 kA (denoted at theright axis) two frequency bands are observed.

diﬀerent toroidal position (Δφ = 135o ) with respect
to the CR-system gives further insight in the magnetic
structure generated by he RMP. Looking at a Mirnov
coil signal during ramp up of IDED (Fig. 8) shows
broad band ﬂuctuations centered at f ≈ 25 kHz. Ata threshold of IDED = 5 kA two sharp bands are observed with the above mentioned frequencies. This
threshold can be related to the formation of a 5/2
island with a certain width. This can be veriﬁed experimentally by decreasing either the DED current orincreasing qa which will decrease the inﬂuence of the
RMP on the island. In both cases the observed frequency bands should disappear, which indeed is thecase.
Upper and lower frequency are a measurement of asecondary structure in the 5/2 island [15]. Further
evidence for this assumptions is found from the estimation of the cross correlation between a top antennae of the CR system and diﬀerent poloidal Mirnov
coils. They show a strong correlation at 19.8 kHz and23.2 kHz (see Fig. 9). Note that for t ≈ 2.1 s a step of
Δ f = 1 GHz in the CR system moves rc more inward,
thus covering the whole island, and detects beside the19.8 kHz line also a line at 23.2 kHz. Knowing the rotation direction of the background plasma, which is inelectron diamagnetic drift (edd) direction the rotation

6. Turbulent Transport in Pump Out
Scenario

A special case of the RMP application at TEXTOR is the pump out scenario, where the RMP yields
a 10-20% reduction in the line averaged density. Alsoa reduction in the eﬀective particle conﬁnement time
(τp∗ ) is found. To ﬁnd the region of enhanced transport, the turbulence properties in this scenario are
analyzed. Therefore the decorrelation time τDC =θF W HM · r/v⊥ and the mean perpendicular wavelength �λ⊥ � = 2π · rc /ζF W HM , where θF W HM andζF W HM denote the full width at half maximum of thepoloidal distribution of the cross and auto correlation
function, respectively, as obtained from diﬀerent antenna combinations of the CR-system [3]. Whereas�λ⊥ � does not change with the RMP a strong decrease in τDC is observed during RMP operation. Thisdecrease is observed more less for the complete radial range under investigation. A signiﬁcant reduction
from 12 μs without DED to 7 μs is observed during
DED operation. Assuming a turbulent transport coeﬃcient based on a simple random walk approach:
RW
Dturb
∼

�λ⊥ �2
τDC

an increase by ≈ 50% is obtained (see Fig. 10).
48

(3)

A. Krämer-Flecken et al., Overview on Turbulence and Structure Formation during Resonant Magnetic Perturbations at TEXTOR

TOR plasmas. Due to laminar and ergodic zones with
open stochastic ﬁeld lines electron losses become dominant and generate a positive Er at the plasma edge.
Also the plasma rotation is eﬀectively reduced over alarge radial range.
The open and stochastic ﬁeld lines forestall the generation of geodesic acoustic modes at the plasma boundary. The measured propagation length for the GAMs
is larger than the connection length to the target.
Since GAMs and zonal ﬂows are discussed as a trigger
for a transition to improved conﬁnement, in that sense
RMPs are not favorable.
A ﬂow in the 5/2 island chain is observed. The obtained frequency gap is explained by the superposition of the ﬂow inside the island with the ﬂow in thesurrounding plasma. In addition indications for secondary structures in the island are found.
The turbulence in the ergodic region is investigatedin the density pump out scenario. A signiﬁcant decrease in the decorrelation time of the turbulence isfound. The estimated turbulence wavelength is notchanged. The random walk turbulent diﬀusion coeﬃcient is therefore enhanced by ≈ 50 % in the ergodic
region. This may be the explanation for the decreasein τp∗ .
In the SOL a reduction of blob transport with theapplication of the RMP is found based on reduced radial E × B transport outside the LCFS. This could
be beneﬁcial for the plasma wall interaction.

80

D∼λ2 /τ

⊥ DC/ m2/s

70
60
50
I

IDED=6kA
I

30
20
0.3

=0kA

DED

40

=2kA

DED

IDED=4kA
0.32

0.34

0.36

r /m

0.38

0.4

0.42

c

RW
Fig. 10Increase of Dturb
during RMP operation in thepump out scenario for diﬀerent values of IDED

7. Blobby Transport
The transport in the scrape of layer (SOL), measured with a reciprocating probe, exhibits intermittency behaviour caused by the abrupt transition fromclosed to open ﬂux surfaces. Due to the E × B transport, blobs, generated at the last close ﬂux surface(LCFS), move into the SOL by 1–2 cm. With the application of RMPs the blob transport is reduced [16].
Fig. 11 a,e shows a reduction in the ion saturation√
current Is ∝ n¯e Te during RMP application. From
Fig. 11 b,f it can be seen that vr is not much changed
during RMP operation. Comparing the radial particle ﬂux Γr = � n˜e v˜r � in Fig. 11 c,g a reduction in Γrby the blobs is observed, when a RMP is applied andwhich agrees with simulations [17], where it is shownthat the radial E × B transport is reduced outside
the last closed ﬂux surface and the mean propagation
length is reduced, thus the blob cannot move into the
SOL.

Acknowledgment This work is performed underthe INTAS contract 1000008-8046.
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pp S730-S742[7] Y. Xu et al., Nucl. Fusion, 47, (2007), pp 1696-1709[8] K.H. Finken et al., Nucl. Fusion, 47, (2007), pp 522534[9] M. W. Jakubowski et al., Plasma Phys. Control. Fusion, 49, (2007), S109-S121[10] K.Itoh et al., Physics of Plasmas 13, 055502 (2006)[11] P. Diamond et al., Plasma Phys. Control. Fusion, 47,(2005), R35[12] T. Ido et al., Plasma Phys. Control. Fusion, 48,(2006), pp S41-S50[13] A. Krämer-Flecken et al., Nucl. Fusion, 44, (2004),
pp 1143-1157[14] K. Ida et al., Nucl. Fusion, 44, (2004), pp 290-295[15] Y. Liang et al., Nucl. Fusion, 47, (2007), pp L21-L25[16] Xu et al., 35th EPS, Hersonissos, Crete, Greece, June
9-13, 2008, O-4.052,[17] D. Reiser, Phys. Plasmas, 14, 082314, (2007)

Fig. 11Comparison of Is , vr and Γr in the SOL before andduring RMP application.

8. Discussion and Conclusion
The paper gives an overview on diﬀerent aspectsof resonant magnetic perturbations, applied at TEX-

49