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SUMMARY:Spontaneous tokamak rotation: observations turbulent momentum tran
 sport has to explain - Hutchinson\, I (Massachusetts Institute of Technolo
 gy)
DTSTART:20100722T084500Z
DTEND:20100722T093000Z
UID:TALK25560@talks.cam.ac.uk
CONTACT:Mustapha Amrani
DESCRIPTION:Ideal tokamaks have axisymmetric magnetic fields that\, by sym
 metry\, cannot impart toroidal angular momentum. Yet\, even without obviou
 s external sources of momentum\, such as neutral-beams\, they rotate at sp
 eeds up to a substantial fraction of the ion thermal speed. This spontaneo
 us rotation is an unequivocal signature of momentum transport (presumably 
 turbulent) *up* the velocity gradient --- that is\, in the opposite direct
 ion to any supposed shear viscosity. Theoretical suggestions for the mecha
 nisms producing spontaneous rotation exist\; but even qualitative confront
 ation of theory with experiment is at a rudimentary stage. This presentati
 on will summarize some key experimental observations that require explanat
 ion. Understanding the spontaneous rotation is vital for future devices li
 ke ITER\, where beam-driven rotation will be small\, and might be relevant
  also in the space and astrophysical context. 
LOCATION:Seminar Room 1\, Newton Institute
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