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PRODID:UW-Madison-Physics-Events
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SEQUENCE:1
UID:UW-Physics-Event-6212
DTSTART:20201207T180000Z
DURATION:PT1H0M0S
DTSTAMP:20260415T010430Z
LAST-MODIFIED:20201203T171609Z
LOCATION: Zoom Meeting
SUMMARY:Demonstration of helium exhaust enhancement during resonant ma
 gnetic perturbation (RMP) field application at DIII-D\, Plasma Physics
  (Physics/ECE/NE 922) Seminar\, Edward Hinson\, UW Engineering Physics
  department
DESCRIPTION:  It is shown for the first time in a diverted tokamak tha
 t<br>
\nkey metrics for continuous fusion\, effective helium particle<
 br>
\nconfinement time\, 𝛕_p*He\, and its ratio with energy confine
 ment\,<br>
\n𝛕_p*He/𝛕_E\, were reduced by a factor of 2-3 during
  suppression of<br>
\nedge localized modes (ELMs) by resonant magnetic
  field perturbations<br>
\n(RMPs) over the unperturbed ELMy case. Redu
 ced 𝛕_p*He during RMP was<br>
\nobserved in the core\, edge\, and p
 ump plenum\, where higher helium<br>
\npressure and concentration were
  also found. Elevated ionized helium<br>
\nline emission during ELM su
 ppression\, with a decay time matching<br>
\n𝛕_p*He\, was measured 
 at the inner strike point\, suggesting more<br>
\nhelium in the unconf
 ined region. These observations suggest that<br>
\nprocesses during ap
 plication of RMPs better retain helium at the edge\,<br>
\nin excess o
 f that expected from deuterium ‘pumpout\,’ where it is<br>
\npumpe
 d more quickly. A multi-reservoir model\, derived from a finite<br>
\n
 volume approximation of the continuity equation with diffusive and<br>
 
\nconvective transport\, fits the helium time evolution at each of th
 e<br>
\nabove-mentioned measurements well. Transport parameters obtain
 ed from<br>
\nthese fits indicate the data are consistent with strongl
 y increased<br>
\ntransport of helium in the separatrix region during 
 RMP application\,<br>
\nalthough higher core transport is also found. 
 These findings\, which<br>
\nwere obtained in ITER-shaped plasmas\, pr
 ovide evidence that<br>
\napplication of RMP ELM suppression in future
  devices such as ITER may<br>
\nbe capable of matching or exceeding th
 e helium impurity exhaust<br>
\nproduced by the ELM events themselves\
 , thereby helping to avoid helium<br>
\nash buildup in a burning regim
 e\, and maintain high fusion gain.<br>
\n<br>
\nConnection information
 :<br>
\n<br>
\nJoin Zoom Meeting<br>
\nhttps://uwmadison.zoom.us/j/991
 56107574?pwd=RnA0ZnJHbDdlOHN1dkpFYUVYcWZpUT09<br>
\n<br>
\nMeeting ID:
  991 5610 7574<br>
\nPasscode: 883688
URL:https://www.physics.wisc.edu/events/?id=6212
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