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VERSION:2.0
PRODID:-//Memento EPFL//
BEGIN:VEVENT
SUMMARY:"Excitation of flow-stabilized resistive wall mode in rotating tok
 amak plasmas"
DTSTART:20141008T103000
DTEND:20141008T113000
DTSTAMP:20260501T092159Z
UID:93ba9edafaba27e9f03ee89f118cfe70e7c9d787717510af66c05b58
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. Nobuyuki AIBA\, Japan Atomic Energy Agency\, J\nMagnetohyd
 rodynamic (MHD) instability in rotating tokamak plasmas is found numerical
 ly for the first time. This instability is excited by the interplay betwee
 n a resistive wall mode (RWM) and a stable MHD mode. When the plasma has a
  stable ideal MHD mode\, a reversed shear Alfven eigenmode (RSAE) for exam
 ple\, this mode is Doppler-shifted by rotating the plasma. The MHD instabi
 lity appears in the case that resistive wall surrounds the plasma and the 
 Doppler-shifted mode frequency approaches to zero. After passing zero freq
 uency\, the unstable mode changes from RWM to a negative energy ideal MHD 
 mode. This destabilization of MHD mode is basically the same as the coupli
 ng between unstable RWM and a stable ideal kink mode in a cylindrical plas
 ma discussed by Lashmore-Davies etc.. In tokamaks\, however\, we found tha
 t not only an external kink mode but also many Alfven eigenmodes can becom
 e the counterparts of the coupling\, and the excited mode can appear even 
 when both RWM and ideal!\nMHD mode are stable. The destabilization is also
  observed even when continuum damping and ion Landau damping effects affec
 t the MHD stability. This result suggests that for steady state high beta 
 tokamaks\, like DEMO\, it is necessary to shape the safety factor profile 
 in such a way that no stable eigenmode exists in the band of rotation freq
 uency.
LOCATION:PPB 019
STATUS:CONFIRMED
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