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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2735
DTSTART:20121119T180000Z
DURATION:PT1H0M0S
DTSTAMP:20260420T021902Z
LAST-MODIFIED:20121114T171641Z
LOCATION:1310 Sterling Hall
SUMMARY:Fast Ion Confinement and Stability of an NBI-heated RFP\, Plas
 ma Physics (Physics/ECE/NE 922) Seminar\, Jay Anderson\, University of
  Wisconsin-Madison
DESCRIPTION:The envisioned burning plasma experiment\, regardless of m
 agnetic concept\, relies on sufficient confinement of the charged fusi
 on products for plasma self heating. As such\, the confinement of fast
  ions and their impact on the bulk plasma are crucial issues. While we
 ll-studied in tokamak\, ST and stellarator plasmas\, relatively little
  is known in RFP plasmas about the dynamics of fast ions and the effec
 ts they cause as a large population. These studies are now underway in
  MST with an intense 25 keV\, 1 MW hydrogen neutral beam injector (300
  MW/m^2 at injection port). Fast particles are confined much better th
 an thermal particles in the stochastic RFP magnetic field\, and a sign
 ificant population of fast ions develops during NB injection. TRANSP s
 imulations predict a super-Alfvenic ion density of up to 25% of the el
 ectron density with both a significant velocity space gradient and a s
 harp radial density gradient. There are several effects on the backgro
 und plasma including enhanced toroidal rotation\, electron heating and
  an altered current density profile. The abundant fast particles affec
 t the plasma stability. Fast ions at the island of the core-most reson
 ant tearing mode have a stabilizing effect\, and up to 60% reduction i
 n the magnetic fluctuation amplitude is observed during NBI. Simultane
 ously\, beam driven instabilities are observed for the first time in t
 he RFP. Repetitive 50 us bursts of m=1 modes have scaling signatures o
 f both Alfvenic and continuum energetic particle modes. The dominant m
 odes are n=4 (EP-like) and n=5 (AE-like)\, which nonlinearly couple to
  an n=1 mode. The feedback of the altered plasma stability on the fast
  ion confinement is investigated.
URL:https://www.physics.wisc.edu/events/?id=2735
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