Multidevice pedestal scaling experiments in the DIII-D, ASDEX Upgrade (AUG), and JET tokamaks are presented in order to test two plasma physics pedestal width models. The first model proposes a scaling of the pedestal width Δ/aρ*1/2 to ρ* based on the radial extent of the pedestal being set by the point where the linear turbulence growth rate exceeds the E×B velocity. In the multidevice experiment where ρ* at the pedestal top was varied by a factor of four while other dimensionless parameters where kept fixed, it has been observed that the temperature pedestal width in real space coordinates scales with machine size, and that therefore the gyroradius scaling suggested by the model is not supported by the experiments. The density pedestal width is not invariant with ρ* which after comparison with a simple neutral fuelling model may be attributed to variations in the neutral fuelling patterns. The second model, EPED1, is based on kinetic ballooning modes setting the limit of the radial extent of the pedestal region and leads to Δψβp1/2. All three devices show a scaling of the pedestal width in normalised poloidal flux as Δψβp1/2, as described by the kinetic ballooning model; however, on JET and AUG, this could not be distinguished from an interpretation where the pedestal is fixed in real space. Pedestal data from all three devices have been compared with the predictive pedestal model EPED1 and the model produces pedestal height values that match the experimental data well.

1.
Editors of “
Progress in the ITER Physics Basis
,” Nucl. Fusion
47
,
S1
(
2007
).
2.
J. W.
Connor
,
Plasma Phys. Control. Fusion
40
,
531
(
1998
).
3.
J. R.
Ferron
 et al.,
26th EPS Conference on Plasma Physics and Controlled Fusion
(1999), Vol. 23J,
p
1201
.
4.
H. R.
Wilson
 et al.,
Phys. Plasmas
9
,
1277
(
2002
).
5.
P. B.
Snyder
 et al.,
Phys. Plasmas
9
,
2037
(
2002
).
6.
G. T. A.
Huysmans
,
Plasma Phys. Controlled Fusion
47
,
B165
(
2005
).
7.
S.
Saarelma
 et al.,
Plasma Phys. Controlled Fusion
51
, xxx (
2009
).
8.
T. H.
Osborne
 et al., in
19th IAEA Fusion Energy Conference
,
Lyon
,
France
,
14
19
October
2002
.
9.
P. B.
Snyder
 et al.,
Nucl. Fusion
44
,
320
(
2004
).
10.
A. E.
Hubbard
 et al.,
Plasma Phys. Controlled Fusion
42
,
A15
(
2000
).
11.
T.
Onjun
 et al.,
Phys. Plasmas
9
(
12
),
5018
(
2002
).
12.
A. W.
Leonard
 et al.,
J. Phys.: Conf. Ser.
123
,
012001
(
2008
).
13.
T. H
Osborne
 et al.,
Plasma Phys. Controlled Fusion
40
,
845
(
1998
).
14.
G.
Saibene
 et al.,
Nucl. Fusion
39
(
9
),
1133
(
1999
).
15.
A.
Kirk
 et al.,
Plasma Phys. Controlled Fusion
46
,
A187
(
2004
).
16.
H.
Urano
 et al.,
Nucl. Fusion
48
, (
2008
).
17.
D. A.
Mossessian
 et al.,
Phys. Plasmas
10
(
3
),
689
(
2003
).
18.
T.H.
Osborne
 et al., in
45th Annual Meeting of the APS Division of Plasma Physics
,
Albuquerque
,
NM
,
27
31
October
2003
, KP1.023.
19.
M. E.
Fenstermacher
, T.
H.
Osborne
 et al.,
Nucl. Fusion
45
,
1493
(
2005
).
20.
G
Maddisson
,
Nucl. Fusion
49
,
125004
(
2009
).
21.
R.
Neu
 et al.,
Phys. Scr.
T138
,
014038
(
2009
).
22.
M. A.
Mahdavi
 et al.,
Nucl. Fusion
42
,
52
(
2002
).
23.
R. J.
Groebner
 et al.,
Plasma Phys. Controlled Fusion
44
,
A265
(
2002
).
24.
I.
Nunes
 et al.,
Nucl. Fusion
44
,
883
(
2004
).
25.
I.
Nunes
 et al.,
Nucl. Fusion
45
,
1550
(
2005
).
26.
J.
Hughes
 et al.,
Phys. Plasmas
13
,
056103
(
2006
).
27.
R. J.
Groebner
 et al.,
Nucl. Fusion
49
,
085037
(
2009
).
28.
P. B.
Snyder
 et al.,
Phys. Plasmas
16
,
056118
(
2009
).
29.
P. B.
Snyder
 et al., in
22nd IAEA Fusion Energy Conference
,
Geneva
,
Switzerland
,
13
18
October 2008.
30.
C. F.
Maggi
 et al.,
Nucl. Fusion
50
,
025023
(
2010
).
31.
R.
Pasqualotto
 et al.,
Rev. Sci. Instrum.
75
,
3891
(
2004
).
32.
M. N. A.
Beurskens
 et al.,
Nucl. Fusion
48
,
095004
(
2008
).
33.
P.
Schneider
 et al., in
37th EPS Conference on Plasma Physics
, Dublin,
2010
, P2.157.
34.
R.
Scannell
 et al.,
Rev. Sci. Instrum.
82
,
053501
(
2011
).
35.
M. N. A.
Beurskens
 et al.,
Plasma Phys. Controlled Fusion
51
,
124051
(
2009
).
36.
A.
Loarte
 et al.,
Plasma Phys. Controlled Fusion
45
,
1549
(
2003
).
37.
M. A.
Mahdavi
 et al.,
Phys. Plasmas
10
(
10
),
3984
(
2003
).
38.
A.
Kallenbach
 et al.,
J. Nucl. Mater.
337–339
,
381
(
2005
).
39.
P. B.
Snyder
 et al., in
23rd IAEA Fusion Energy Conference, Daejeon, Korea
, 11-16 October 2010.
40.
A.
Kirk
 et al.,
Plasma Phys. Controlled Fusion
51
,
065016
(
2009
).
41.
L.
Barrera
 et al.,
Plasma Phys. Controlled Fusion
52
,
085010
(
2010
).
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