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Dependence of Edge Stability on Plasma Shape and Local Pressure Gradients in the DIII-D and JT-60U Tokamaks...

Publication Type
Conference Paper
Book Title
CD: IAEA 18TH Conference Proceedings
Publication Date
Page Numbers
151 to 300
Conference Name
18th IAEA Fusion Energy Conference
Conference Location
Sorrento, Italy
Conference Sponsor
International Atomic Energy Agency (IAEA)
Conference Date

The dependence of edge stability on plasma shape and local pressure gradients, P, in the DIII-D and JT-60U tokamaks is studied. The stronger plasma shaping in DIII-D allows the edge region of DIII-D discharges with Type I ("giant") ELMs to have access to the second region of stability for ideal ballooning modes and larger edge P′than JT-60U Type I ELM discharges. These JT-60U discharges are near the ballooning mode first regime stability limit. DIII-D results support an ideal stability based working model of Type I ELMs as low to intermediate toroidal mode number, n, MHD modes. Results from stability analysis of JT-60U Type I ELM discharges indicate that predictions from this model are also consistent with JT-60U edge stability observations.