Observation of edge instability limiting the pedestal growth in tokamak plasmas.
With fusion device performance hinging on the edge pedestal pressure, it is imperative to experimentally understand the physical mechanism dictating the pedestal characteristics and to validate and improve pedestal predictive models. This Letter reports direct evidence of density and magnetic fluctuations showing the stiff onset of an edge instability leading to the saturation of the pedestal on the Alcator C-Mod tokamak. Edge stability analyses indicate that the pedestal is unstable to both ballooning mode and kinetic ballooning mode in agreement with observations.
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
A
A
Diallo
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J W
JW
Hughes
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
M
M
Greenwald
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
B
B
Labombard
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
E
E
Davis
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
S-G
SG
Baek
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
C
C
Theiler
General Atomics, San Diego, California 92186, USA.
P
P
Snyder
Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
J
J
Canik
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J
J
Walk
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
T
T
Golfinopoulos
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
J
J
Terry
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
M
M
Churchill
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
A
A
Hubbard
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
M
M
Porkolab
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA.
L
L
Delgado-Aparicio
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
M L
ML
Reinke
Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
A
A
White
Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA and Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA and General Atomics, San Diego, California 92186, USA and Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Alcator C-Mod Team