Abstract
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 a larger edge pedestal pressure gradient P′ than JT-60U type I ELM discharges. These JT-60U discharges are near the ballooning mode first regime stability limit. The DIII-D results support an ideal stability based working model of type I ELMs as low to intermediate toroidal mode number, n, MHD modes. The results from a stability analysis of JT-60U type I ELM discharges indicate that the predictions of this model are also consistent with JT-60U edge stability observations.
Original language | English |
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Pages (from-to) | 295-300 |
Number of pages | 6 |
Journal | Nuclear Fusion |
Volume | 41 |
Issue number | 3 |
DOIs | |
State | Published - Mar 2001 |