Abstract
We report observations of the first low-to-high ([Formula presented]) confinement mode transitions in the National Spherical Torus Experiment. The [Formula presented]-mode energy confinement time increased over reference discharges transiently by [Formula presented], as high as [Formula presented]. This confinement time is [Formula presented] times higher than predicted by a multimachine scaling. Thus the confinement time of spherical tori has been extended to a record high value, leading to an eventual revision of confinement scalings. Finally, the power threshold for [Formula presented]-mode access is [Formula presented] higher than predicted by an international scaling from conventional aspect-ratio tokamaks, which could lead to new understanding of [Formula presented]-mode transition dynamics.
Original language | English |
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Pages (from-to) | 4 |
Number of pages | 1 |
Journal | Physical Review Letters |
Volume | 88 |
Issue number | 3 |
DOIs | |
State | Published - 2002 |