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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:1
UID:UW-Physics-Event-8880
DTSTART:20240923T170500Z
DTEND:20240923T180000Z
DTSTAMP:20260413T184622Z
LAST-MODIFIED:20240903T144349Z
LOCATION:1610 Engineering Hall
SUMMARY:Experimental and Modeling Results from the HSX Stellarator\, P
 lasma Physics (Physics/ECE/NE 922) Seminar\, Alexis Wolfmeister\, Univ
 ersity of Wisconsin-Madison
DESCRIPTION:The Helically Symmetric eXperiment (HSX) is an optimized s
 tellarator with a major radius of 1.2 m and a 1 Tesla magnetic field l
 ocated in Engineering Hall here at UW-Madison. Previous work has shown
  that the unique quasi-helical magnetic field configuration of HSX all
 ows for large intrinsic flows in the direction of symmetry [1] and red
 uces neoclassical transport [2] so that transport is predominantly dri
 ven by trapped electron mode turbulence [3].HSX is equipped with a set
  of auxiliary coils which are used to study the effects of magnetic fi
 eld geometry on plasma confinement.<br>
\n<br>
\nExcellent plasma perf
 ormance has been achieved following an intensive first wall reset\, wh
 ich involved removing coatings deposited on the plasma facing stainles
 s steel wall\, combined with a new vessel baking system and extensive 
 glow discharge cleaning. The resulting reduction in impurity content h
 as driven substantial improvements in plasma profiles\, including core
  electron temperatures well above 2 keV and higher overall energy conf
 inement. <br>
\n<br>
\nDuring studies with different main-ion species\
 , more pronounced electron temperature profile peaking has been measur
 ed in hydrogen fueled plasmas than with helium fueling. This is consis
 tent with non-linear GENE [4] simulations which predict reduced turbul
 ent heat fluxes in hydrogen plasmas. Although previous work suggested 
 the strong electron temperature peaking observed in the core of HSX is
  a result of turbulent suppression by ExB flow shear\, recent analysis
  of correlation ECE measurements have shown increased radiation temper
 ature fluctuations in regions with high electron temperature gradients
 . These measurements show qualitative agreement with non-linear gyroki
 netic flux tube simulations with GENE.<br>
\n<br>
\n[1] A. Briesemeist
 er et al.\, 2010 Contrib. Plasma Phys. 50 8<br>
\n[2] J. Canik et al.\
 , 2007 Phys. Rev. Lett. 98 8<br>
\n[3] W. Guttenfelder et al.\, 2008 P
 hys. Rev. Lett. 101 21<br>
\n[4] F. Jenko et al.\, 2000 Phys. Plasmas 
 7 1904<br>
\n[5] M.J. Gerard et al.\, 2023 Nucl. Fusion 63 056004<br>

 \n*Work supported by US DOE Grant No. DE-FG02-93ER54222
URL:https://www.physics.wisc.edu/events/?id=8880
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