title: Pedestal bifurcation and resonant field penetration at the threshold of edge-localized mode suppression in the DIII-D Tokamak.
abstract: Rapid bifurcations in the plasma response to slowly varying n=2 magnetic fields are observed as the plasma transitions into and out of edge-localized mode (ELM) suppression. The rapid transition to ELM suppression is characterized by an increase in the toroidal rotation and a reduction in the electron pressure gradient at the top of the pedestal that reduces the perpendicular electron flow there to near zero. These events occur simultaneously with an increase in the inner-wall magnetic response. These observations are consistent with strong resonant field penetration of n=2 fields at the onset of ELM suppression, based on extended MHD simulations using measured plasma profiles. Spontaneous transitions into (and out of) ELM suppression with a static applied n=2 field indicate competing mechanisms of screening and penetration of resonant fields near threshold conditions. Magnetic measurements reveal evidence for the unlocking and rotation of tearinglike structures as the plasma transitions out of ELM suppression.
authors: Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA.
authors: R
authors: R
authors: Nazikian
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: C
authors: C
authors: Paz-Soldan
authors: University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706-1609, USA.
authors: J D
authors: JD
authors: Callen
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: J S
authors: JS
authors: deGrassie
authors: University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417, USA.
authors: D
authors: D
authors: Eldon
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: T E
authors: TE
authors: Evans
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: N M
authors: NM
authors: Ferraro
authors: Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA.
authors: B A
authors: BA
authors: Grierson
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: R J
authors: RJ
authors: Groebner
authors: Plasma Research Laboratory, Australian National University, Canberra, ACT 0200, Australia.
authors: S R
authors: SR
authors: Haskey
authors: University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706-1609, USA.
authors: C C
authors: CC
authors: Hegna
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: J D
authors: JD
authors: King
authors: Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA.
authors: N C
authors: NC
authors: Logan
authors: University of Wisconsin-Madison, 1500 Engineering Drive, Madison, Wisconsin 53706-1609, USA.
authors: G R
authors: GR
authors: McKee
authors: University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417, USA.
authors: R A
authors: RA
authors: Moyer
authors: Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA.
authors: M
authors: M
authors: Okabayashi
authors: University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417, USA.
authors: D M
authors: DM
authors: Orlov
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: T H
authors: TH
authors: Osborne
authors: Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA.
authors: J-K
authors: JK
authors: Park
authors: University of California, Los Angeles, Los Angeles, California 90095, USA.
authors: T L
authors: TL
authors: Rhodes
authors: Oak Ridge National Laboratory, PO Box 2008, Oak Ridge, Tennessee 37831, USA.
authors: M W
authors: MW
authors: Shafer
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: P B
authors: PB
authors: Snyder
authors: Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543-0451, USA.
authors: W M
authors: WM
authors: Solomon
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: E J
authors: EJ
authors: Strait
authors: General Atomics, PO Box 85608, San Diego, California 92186-5608, USA.
authors: M R
authors: MR
authors: Wade