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Turbulence intermittency in the confinement region
of I-mode plasmas in the ASDEX Upgrade tokamak
ASDEX Upgrade
Helmholtz Virtual Institute for Plasma Dynamical Processes and Turbulence Studies using Advanced Microwave Diagnostics
T. Happel,1 P. Manz,1,2 F. Ryter,1 M. Bernert,1 M. Dunne,1 P. Hennequin,3 A. Hetzenecker,1 G. D. Conway,1 L. Guimarais,4 C. Honoré,3 U. Stroth,1 E. Viezzer1
and the ASDEX Upgrade Team1
1Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany2Physik-Department E28, Technische Universität München, James-Franck-Str. 1, 85748, Garching, Germany3Laboratoire de Physique des Plasmas, Ecole Polytechnique, 91128 Palaiseau, France4Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Universidade de Lisboa, Portugal
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 2
ASDEX Upgrade
Outline
■ Weakly coherent mode and geodesic acoustic mode
■ Existence
■ Coupling
■ Intermittent density bursts
■ Linked to the WCM
■ Impact on divertor
■ Peeling-Ballooning stability analysis
■ Summary
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 3
ASDEX Upgrade
Pronounced temperature pedestal in I-mode
nb: heating power different for L-mode / I-mode
#30865
[Manz NF 2015]
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 4
ASDEX Upgrade
Both WCM and GAM are observed in I-mode
#30865
■ Both GAM and WCM observed in I-mode
■ GAM obtained from conventional reflectometry
via envelope method [Nagashima PPCF 2007]
[Manz NF 2015]
HP f > 400 kHz
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 5
ASDEX Upgrade
Both WCM and GAM are observed in I-mode
#30865
■ Both GAM and WCM observed in I-mode
■ GAM obtained from conventional reflectometry
via envelope method [Nagashima PPCF 2007]
[Manz NF 2015]
HP f > 400 kHz
Energy input
[Cziegler PoP 2013]
Alcator C-Mod
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 6
ASDEX Upgrade
Both WCM and GAM are observed in I-mode
#30865
density fluctuationsve
loci
ty f
luc
tua
tio
ns
cro
ss-b
ico
he
ren
ce
#30865
■ GAM and WCM coupled in I-mode
GAM determines WCM width⇒
■ Mode in Bpol is a geodesic alfvénic mode and
not related to the WCM[Manz NF 2015]
HP f > 400 kHz
~
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 7
ASDEX Upgrade
Temportal evolution of an I-mode discharge
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 8
ASDEX Upgrade
Temportal evolution of an I-mode discharge
0.96 0.97 0.98 0.99 1.00-10
-5
0
5
10
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sne prof.
ρpol
v ⊥ (
km/s
)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 9
ASDEX Upgrade
Temportal evolution of an I-mode discharge
0.96 0.97 0.98 0.99 1.00-10
-5
0
5
10
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sne prof.
ρpol
v ⊥ (
km/s
)
0.96 0.97 0.98 0.99 1.00-20
-10
0
10
20
ρpolE
r (kV
/m)
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sne prof.
v⊥ = vExB + vph
⇒ Er = v⊥B
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 10
ASDEX Upgrade
Improved confinement correlated with deeper edge Er
■ Separation between L- and H-mode in both
H98(y,2) and Er minimum
CXRS data from [Viezzer PPCF 2014]
0.2 0.4 0.6 0.8 1.0 1.2H98(y,2)
-50
-40
-30
-20
-10
0
Min
Er(k
V/m
)
DRCXRS
L-modeI-modeH-mode
open symb.:Bt > 0
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 11
ASDEX Upgrade
Improved confinement correlated with deeper edge Er
■ Separation between L- and H-mode in both
H98(y,2) and Er minimum
■ I-mode could be thought of a regime “in
between” for unfavorable configurations
- like I-phase in favorable configurations
■ Improved I-mode confinement accompanied
by a deeper Er compared to L-mode
CXRS data from [Viezzer PPCF 2014]
0.2 0.4 0.6 0.8 1.0 1.2H98(y,2)
-50
-40
-30
-20
-10
0
Min
Er(k
V/m
)
L-modeI-modeH-mode
open symb.:Bt > 0
DRCXRS
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 12
ASDEX Upgrade
In I-mode, less turbulence, but strong bursts
-3000
-2000
-1000
0
1000
2000
3000
f (kH
z)
-120
-111
-102
-93
-84
-75
-66
-58
Turb
ulen
ce le
vel (
dB)
1.8 1.9 2.0 2.1 2.2 2.3 2.4Time (s)
10-7
10-6
10-5
10-4
Int.
Powe
r (a.
u.)
AUG #29744
L-mode I-mode Hk⊥ = 12.1 cm-1
∝ Turbulence level
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 13
ASDEX Upgrade
Turbulence in I-mode shows burst character
2.080 2.082 2.084 2.086 2.088 2.0900.00
0.05
0.10
0.15Tu
rb.
Ampl
itude
(a.u
.)L-mode, pol = 0.99
I-mode, pol = 0.99
AUG #29744
2.380 2.382 2.384 2.386 2.388 2.390Time (s)
0.00
0.05
0.10
0.15
Turb
.Am
plitu
de (a
.u.)
0 5 10 15 20Amplitude (σL)
10-5
10-4
10-3
10-2
10-1
100
(Am
plitu
de)
I-mode
L-modeAUG #29744
■ Substantial difference between L-mode
and I-mode turbulence behavior
■ I-mode PDF develops heavy tail at large
amplitudes
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 14
ASDEX Upgrade
Evolution of PDF continuous, no abrupt change at L-I transition
2.0 2.1 2.2 2.3 2.4 2.5Time (s)
5
10
15
20
Turb
ulen
ce A
mpl
itude
(σL)
-5
-4
-3
-2
-1
0
Log(
PDF)
L-mode I-mode HAUG #29744
■ In H-mode, turbulence reduced
substantially
■ PDF evolves continuously
from L-mode to I-mode
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 15
ASDEX Upgrade
2.0 2.1 2.2 2.3 2.4 2.5Time (s)
5
10
15
20
Turb
ulen
ce A
mpl
itude
(σL)
-5
-4
-3
-2
-1
0
Log(
PDF)
L-mode I-mode HAUG #29744
= [2, 6]
= [10, 22]
= [6, 10]
0
2
4
6 = [2, 6]
L-mode I-mode H
0.00.51.01.52.02.53.0 = [6, 10]
2.1 2.2 2.3 2.4Time (s)
0.00.51.01.52.02.5 = [10, 22]
Mea
n(PD
F) (1
0-2)
Mea
n(PD
F) (1
0-3)
Mea
n(PD
F) (1
0-4)
Evolution of PDF continuous, no abrupt change at L-I transition
■ From L to I:
► more high turb. amplitudes
► less low turb. amplitudes
■ In H-mode, turbulence reduced
substantially
■ PDF evolves continuously
from L-mode to I-mode
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 16
ASDEX Upgrade
Intermittency increases with I-mode confinement
0 200 400 600 800 1000Frequency (kHz)
0.0
0.5
1.0
1.5
2.0
2.5
Fla
tnes
s (1
012)
(L) 2.00 - 2.01 s
2.40 - 2.41 s
0.41
0.86
AUG #29744
labels: H98(y,2)
Flatness definition:
F =⟨v
HP4⟩
⟨v
HP2⟩2
Frisch, Turbulence,Cambridge Univ. Press
■ Flatness increase with
confinement
intermittency increases⇒
■ Localized in frequency range
frequency corresponds to burst
duration (~5 μs)
[Happel NF 2016, submitted]
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 17
ASDEX Upgrade
Intermittency increases with I-mode confinement
0 200 400 600 800 1000Frequency (kHz)
0.0
0.5
1.0
1.5
2.0
2.5
Fla
tnes
s (1
012)
(L) 2.00 - 2.01 s2.20 - 2.21 s2.25 - 2.26 s
2.30 - 2.31 s2.35 - 2.36 s2.40 - 2.41 s
0.410.53
0.61
0.670.80
0.86
AUG #29744
labels: H98(y,2)
■ Flatness increase with
confinement
intermittency increases⇒
■ Localized in frequency range
frequency corresponds to burst
duration (~5 μs)
■ Flatness increases
continuously
F =⟨v
HP4⟩
⟨v
HP2⟩2
Flatness definition:
Frisch, Turbulence,Cambridge Univ. Press
[Happel NF 2016, submitted]
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 18
ASDEX Upgrade
Density bursts are linked to the WCM
-3000-2000-1000 0 1000 2000 3000Frequency (kHz)
-50-40-30-20-10
0 AUG #30865t = 3.8885 - 3.8887 s
Doppler reflectometryDopplerpeak
I-mode
L-mode
1 10 100 1000Frequency (kHz)
-90-80
-70
-60-50
Spec
tral P
ower
(dB)
WCM
Conv. reflectometryρpol = 0.985
106.8 104.7 107.4 106.8
-2200 -2100 -2000 -1900 -1800 -1700 -1600Frequency (kHz)
02
4
68
Spec
tral P
ower
(dB)
Spec
tral P
ower
(a.u
.)
ρpol = 0.992
■ In contrast to L-mode, I-mode
Doppler peak often discretized
■ Separation of sub-peaks
corresponds to WCM frequency
■ Reason: FM modulation of
backscattered signal
[Happel NF 2016, submitted]
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 19
ASDEX Upgrade
Density bursts are linked to the WCM
-3000-2000-1000 0 1000 2000 3000Frequency (kHz)
-50-40-30-20-10
0 AUG #30865t = 3.8885 - 3.8887 s
Doppler reflectometryDopplerpeak
I-mode
L-mode
1 10 100 1000Frequency (kHz)
-90-80
-70
-60-50
Spec
tral P
ower
(dB)
WCM
Conv. reflectometryρpol = 0.985
106.8 104.7 107.4 106.8
-2200 -2100 -2000 -1900 -1800 -1700 -1600Frequency (kHz)
02
4
68
Spec
tral P
ower
(dB)
Spec
tral P
ower
(a.u
.)
0 50 100 150 200Frequency (kHz)
-45-40
-35
-30
-25
-20
Spec
tral P
ower
(dB)
(i)
(ii)
(iii)
conv. reflectometry
-150 -100 -50 0 50 100Time rel. to burst (μs)
0.00.2
0.4
0.6
0.8
1.0
Turb
. am
p. (a
.u.)
+ of
set
(i) #30865
(iii) #29741
(ii) #29744
ρpol = 0.992
■ In contrast to L-mode, I-mode
Doppler peak often discretized
■ Separation of sub-peaks
corresponds to WCM frequency
■ Reason: FM modulation of
backscattered signal
■ Connection WCM – bursts also
observed in time traces
■ Correlation shown, causality
would involve energy transfer
treatment → not possible at the
moment[Happel NF 2016, submitted]
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 20
ASDEX Upgrade
Temporal evolution of bursts (AXUV diode bolometry)
1.0 1.2 1.4 1.6 1.8 2.0 2.2R (m)
-1.0
-0.5
0.0
0.5
1.0
Z (m
)
DDC 27
DDC 28
DR
#29744, t = 2.4 sDR
DDC 28DDC 27
0 200 400 600 800Time (μs)
0.00
0.02
0.04
0.06
0.08
4.0
4.1
4.2
4.3
4.4
Turb
. am
plitu
de (a
.u.)
SP B
olom
etry
(a.u
.)
■ Bursts visible in bolometry → end in divertor ?
■ Bursts first seen in Doppler reflectometry
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 21
ASDEX Upgrade
Temporal evolution of bursts (AXUV diode bolometry)
1.0 1.2 1.4 1.6 1.8 2.0 2.2R (m)
-1.0
-0.5
0.0
0.5
1.0
Z (m
)
DHC 42
DHC 43
DDC 27
DDC 28
DR
#29744, t = 2.4 sDR
DHC 43DHC 42x3
DDC 28DDC 27
0 200 400 600 800Time (μs)
0.00
0.02
0.04
0.06
0.08
9
10
11
12
134.0
4.1
4.2
4.3
4.4
Turb
. am
plitu
de (a
.u.)
SP B
olom
etry
(a.u
.)LF
S Bo
lom
etry
(a.u
.)
■ Bursts visible in bolometry → end in divertor ?
■ Bursts first seen in Doppler reflectometry
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 22
ASDEX Upgrade
Temporal evolution of bursts (AXUV diode bolometry)
1.0 1.2 1.4 1.6 1.8 2.0 2.2R (m)
-1.0
-0.5
0.0
0.5
1.0
Z (m
)
DHC 42
DHC 43
DDC 27
DDC 28
DVC 48
DVC 3
DR
#29744, t = 2.4 sDR
DHC 43DHC 42x3
DDC 28DDC 27
0 200 400 600 800Time (μs)
x5
DVC 48DVC 3
0.00
0.02
0.04
0.06
0.08
9
10
11
12
134.0
4.1
4.2
4.3
4.4
67
8
9
1011
Turb
. am
plitu
de (a
.u.)
SP B
olom
etry
(a.u
.)LF
S Bo
lom
etry
(a.u
.)LF
S/SP
Bol
omet
ry(a
.u.) ■ Bursts visible in bolometry → end in divertor
■ Bursts first seen in Doppler reflectometry
■ Generation in edge plasma → expelled
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 23
ASDEX Upgrade
I-mode is peeling-ballooning stable
■ Stability calculated with the MISHKA
code
■ H-mode close to instability boundary
type-I ELMs⇒
■ I-mode peeling-ballooning stable
no type-I ELMs⇒
■ Observations agree with those
obtained for Alcator C-Mod
[Hughes NF 2013, Walk PoP 2014]
0 1 2 3 4
0.0
0.2
0.4
0.6
0.8
j|| (M
A/m
2 )
H-modeI-modeL-mode
stab. boundary (H-Mode)
stab. boundary (I-Mode)
AUG #29741
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 24
ASDEX Upgrade
■ Both WCM and GAM are observed and they are coupled
■ H98(y,2) and Er well depth fill “gap” between L- and H-mode
■ General reduction of density turbulence level
■ Emergence of strong isolated turbulence bursts (at k⊥ = 11 – 13 cm-1)
► also observed by bolometry (and magnetics)
► linked to WCM, causality not clear
► generated in edge plasma, end up in divertor
► peeling-ballooning stable (no type-I ELMs)
■ Next steps:
► Investigate turbulence bursts at different k⊥
► Study B-field power threshold dependence (PL-I, PI-H)
Summary
In I-mode:
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 25
ASDEX Upgrade
Comparison DR – CXRS
Er_DR_2.0Er_DR_2.2Er_DR_2.3ER_DR_2.4ER_DR_2.5ER_DR_2.6
EC_CX_2.23ER_CX_2.35ER_CX_2.46ER_CX_2.57ER_CX_2.65
Er (
kV/m
)
ρpol
0.98 0.99 1.00-20
-10
0
10
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 26
ASDEX Upgrade
Envelope method
S(f)
f
vGAM = 0
f1 f2
vGAM > 0vGAM < 0
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 27
ASDEX Upgrade
Is there a connection bursts WCM?
-45
-40
-35
-30
-25
-20
S(f)
(dB)
0 50 100 150 200f (kHz)
conv. Reflectometry
#29744, #30865
0.000
0.010
0.020
0.000
0.010
0.020
0.030
-60 -40 -20 0 200.0000.0040.008
0.012
#29744, #30865, Doppler Reflectometry
1/Δt ≈ 120 kHz
rel. time to burst (μs)
1/Δt ≈ 105 kHz
1/Δt ≈ 75 kHzTur
bule
nce
ampl
itude
(a.
u.)
■ Small oscillations before burst
■ Frequency agrees roughly with
WCM from conv. Reflectometry
■ Effect is more obvious for
stronger bursts
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 28
ASDEX Upgrade
WCM is weakly coherent because of GAM
Energy input
[Cziegler PoP 2013]
Alcator C-Mod
Temporal evolution of bursts
1.0 1.2 1.4 1.6 1.8 2.0 2.2R (m)
-1.0
-0.5
0.0
0.5
1.0
Z (m
)
DHC 42
DHC 43
DDC 27
DDC 28
DDC 29
DVC 48
DVC 3
DR
#29744, t = 2.4 s
0.00
0.02
0.04
0.06
0.08DR
9
10
11
12
13DHC 43DHC 42x3
4.0
4.1
4.2
4.3
4.4
DDC 29DDC 28DDC 27
0 200 400 600 800Time (μs)
6
7
8
9
10
11
x5
DVC 48DVC 3
Turb
. am
plitu
de (a
.u.)
SP B
olom
etry
(a.u
.)LF
S Bo
lom
etry
(a.u
.)LF
S/SP
Bol
omet
ry(a
.u.)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 30
ASDEX Upgrade
Temporal Evolution of a typical I-mode (USN)
AUG #29741
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7Time (s)L-mode I-mode H
Pheat
(MW)
ne(1019 m-2)
Teped.top
(keV)
H98(y,2)
-86-58-30-3
S(f)
(dB)
04080
120f (kHz)
Reflectometry WCM
NBI
ECRHohmic
core
edge
012
0246
0.0
0.4
0.8
0.0
0.5
1.0
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 31
ASDEX Upgrade
Pheat
(MW)
ne(1019 m-2)
Teped.top
(keV)
H98
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7Time (s)
-86-58-30-3
S(f)
(dB)
04080
120f (kHz)
Reflectometry WCM
L-mode I-mode H
AUG #29741NBI
ECRHohmic
core
edge
012
0246
0.0
0.4
0.8
0.0
0.5
1.00.96 0.97 0.98 0.99 1.00
-10
-5
0
5
10
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sn e prof.
ρpol
u ⊥ (
km/s
)
u⊥ = vExB + vph
Temporal Evolution of a typical I-mode (USN)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 32
ASDEX Upgrade
Pheat
(MW)
ne(1019 m-2)
Teped.top
(keV)
H98
2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7Time (s)
-86-58-30-3
S(f)
(dB)
04080
120f (kHz)
Reflectometry WCM
L-mode I-mode H
AUG #29741NBI
ECRHohmic
core
edge
012
0246
0.0
0.4
0.8
0.0
0.5
1.00.96 0.97 0.98 0.99 1.00
-10
-5
0
5
10
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sn e prof.
ρpol
u ⊥ (
km/s
)
0.96 0.97 0.98 0.99 1.00
-20
-10
0
10
20
ρpol
Er (
kV/m
)
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sn e prof.
u⊥ = vExB + vph
⇒ Er = u⊥B
Temporal Evolution of a typical I-mode (USN)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 33
ASDEX Upgrade
Strong variation in u⊥ of different bursts
-3000
-2000
-1000
0
1000
2000
3000
f (kH
z)
-120
-109
-98
-87
-76
-65
-54
-44
S(f)
(dB)
2.572 2.574 2.576 2.578 2.580Time (s)
AUG #29741 ρpol = 0.992 (~Er min)
k⊥ = 12.3 cm-1
■ Doppler shift:
fD = u⊥k⊥/2π
mirror peaks due to a technical issue (not real)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 34
ASDEX Upgrade
Strong variation in u⊥ of different bursts
-3000
-2000
-1000
0
1000
2000
3000
f (kH
z)
-120
-109
-98
-87
-76
-65
-54
-44
S(f)
(dB)
2.572 2.574 2.576 2.578 2.580Time (s)
AUG #29741 ρpol = 0.992 (~Er min)
k⊥ = 12.3 cm-1
■ Doppler shift:
fD = u⊥k⊥/2π
■ Different bursts at different u⊥
► candidate: GAM
■ Possible ur influence?
► not likely since comparison with Er u⊥B from CXRS agrees well
mirror peaks due to a technical issue (not real)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 35
ASDEX Upgrade
Strong variation in u⊥ of different bursts
-3000
-2000
-1000
0
1000
2000
3000
f (kH
z)
-120
-109
-98
-87
-76
-65
-54
-44
S(f)
(dB)
2.572 2.574 2.576 2.578 2.580Time (s)
AUG #29741
0.96 0.97 0.98 0.99 1.00
-10
-5
0
5
10
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.40-2.50 s
2.50-2.60 s
2.60-2.66 sn e prof.
ρpol
u ⊥ (
km/s
)AUG #29741
(L) 2.00-2.10 s
2.20-2.30 s2.30-2.40 s
2.50-2.60 s
n e prof.
0.96 0.97 0.98 0.99 1.00
-10
-5
0
5
10
ρpol
u ⊥ (
km/s
)
AUG #29741
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 36
ASDEX Upgrade
Bursts clearly visible in magnetic signals- all y-axis equivalent
1.0 1.5 2.0 2.5R (m)
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Z (m
)
1.5 ms
dBpol
dt
0.020.040.060.080.10
Turb
ulen
ceam
plitu
de (a
.u.)
1.5 ms0.00
Turb. amplitude
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 37
ASDEX Upgrade
1.0 1.5 2.0 2.5R (m)
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Z (m
)
1.5 ms
dBpol
dt
Bursts clearly visible in magnetic signals- all y-axis equivalent
0.020.040.060.080.10
Turb
ulen
ceam
plitu
de (a
.u.)
1.5 ms0.00
Turb. amplitude
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 38
ASDEX Upgrade
1.0 1.5 2.0 2.5R (m)
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Z (m
)
1.5 ms1.5 ms
1.5 ms
Turb. amplitude dBpol
dt
Bursts clearly visible in magnetic signals- all y-axis equivalent
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 39
ASDEX Upgrade
Bursts clearly visible in magnetic signals- all y-axis scaled to respective data
1.0 1.5 2.0 2.5R (m)
-1.5
-1.0
-0.5
0.0
0.5
1.0
1.5
Z (m
)
1.5 ms
Turb. amplitude dBpol
dt
20
-20
20
-20
20
-20
4
-4
6
-6
4
-4
1.5
-1.5
0.2
-0.2
0.6
-0.60.5
-0.5
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 40
ASDEX Upgrade
Mode in magnetics signals is (m,n) = (1,1) sawtooth precursor
-100-84
-69
-53
-38
-22
-78
S(f)
(dB)
0
5
10
15
20
25
30
f (kH
z)
2.1 2.2 2.3 2.4Time (s)
12
3Te
(keV
) inv. radius: rho_pol = 0.48
0
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 41
ASDEX Upgrade
The I-mode at Alcator C-Mod
I-mode: improved confinement regime
► Increased energy confinement
► L-mode like particle confinement
► No ELMs, no impurity accumulation
Turbulence in I-mode
► Reduced fluctuation level (ñe/ne &Te/Te)
► Weakly Coherent Mode (WCM, 100 – 300 kHz)
► WCM coupled to GAM [Cziegler PoP 2013]
~
Whyte NF 2010Hubbard PoP 2011
IAEA 2014
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 42
ASDEX Upgrade
L- and H-mode PDFs compared to distribution functions
10-5
10-4
10-3
10-2
10-1
100PD
F (A
mpl
itude
) burrdagumgammagengammalognormalweibull
burrdagumgammagengammalognormalweibull
L-mode
AUG #29744
0 2 4 6 8 10 12 14Amplitude (L)
0.0
0.5
1.0
1.5
2.0
(Am
plitu
de)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 43
ASDEX Upgrade
Kurtosis – Skewness dependence parabolic as in SOL investigations of toroidal plasmas
0 2 4 6 8 10 12 14Skewness
0
50
100
150
200
250
Kurto
sis
AUG #29744
0 1 2 3 40
5
10
15
20L-mode
I-mode
Fit: K = 1.45 S2
Garcia PRL 2012 Theory for Gamma distribution:K = 1.5 S2
In agreement with measurements in the SOL of toroidal devicesGraves CJP 2005, Labit PRL 2007, Sattin PPCF 2009, Garcia JNM 2013
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 44
ASDEX Upgrade
Edge turbulence changes drastically during L–I–H transition
-2000
-1000
0
1000
2000
f (kH
z)
-120
-108
-96
-84
-72
-60
-48
-36
S(f)
(dB)
1.8 2.0 2.2 2.4 2.6Time (s)
10-710-6
10-5
10-4
10-310-2
Int.
Powe
r (a.
u.)
AUG #29741
k⊥ = 12.1 cm-1
f scan
(rad. inw.)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 45
ASDEX Upgrade
Turbulence in I-mode shows burst character
2.080 2.082 2.084 2.086 2.088 2.0900.00
0.05
0.10
0.15
Turb
.Am
plitu
de (a
.u.)
L-mode, pol = 0.99
I-mode, pol = 0.99
AUG #29744
2.380 2.382 2.384 2.386 2.388 2.390Time (s)
0.00
0.05
0.10
0.15
Turb
.Am
plitu
de (a
.u.)
2.3853 2.3854 2.3855 2.3856Time (s)
0.000.020.040.060.080.100.120.14
Turb
.Am
plitu
de (a
.u.)
-4 -2 0 2 4rel. Time (s)
-0.15
-0.10
-0.05
-0.00
0.05
0.10
0.15
I, Q
, Am
p
IQAmp.
Fit
-100
-50
0
50
100
Phas
e (ra
d)
16th Transport and Confinement Topical Group Meeting • Ahmedabad, India • 16 March 2016T. Happel 46
ASDEX Upgrade
I-modes in AUG with ECRH, LSN reversed Ip/Bt (2009)
Ryter NF 2015, to be submitted
Unfavorable configuration for I-mode
► Here: reversed Ip/Bt
► Later: Upper Single Null (USN)
I-mode starts at ~2.3 s:
► Ploss reduced better confinement⇒
► Density barely changes
► Significant temperature rise
► H98(y,2) between 0.6 and 0.8