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PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:2
UID:UW-Physics-Event-8496
DTSTART:20231113T180000Z
DTEND:20231113T191500Z
DTSTAMP:20260408T171712Z
LAST-MODIFIED:20231104T163431Z
LOCATION:1610 Engineering Hall
SUMMARY:Global fluid simulations of plasma turbulence in stellarators\
 , Plasma Physics (Physics/ECE/NE 922) Seminar\, Antonio Coelho\, EPFL\
 , the Swiss Federal Institute of Technology in Lausanne\, France
DESCRIPTION:<br>
\nWe present the first 3D\, global\, two-fluid\, flux
 -driven simulations of plasma turbulence in stellarators with differen
 t configurations: one with an island divertor\; another one correspond
 ing to the TJ-K stellarator\; and a set of equilibria with increasing 
 torsion and ellipticity. The simulations were carried out with the GBS
  code [1]\, which solves the two-fluid drift-reduced Braginskii equati
 ons.<br>
\n<br>
\n	The vacuum magnetic field of the island divertor co
 nfiguration corresponds to a 5-field period stellarator and was constr
 ucted using the Dommaschk potentials [2]. It was found that the radial
  particle and heat transport is mainly driven by a field-aligned mode 
 with low poloidal wavenumber\, whose origin is investigated theoretica
 lly [3]. Transport is observed to be larger on the high-field side of 
 the device and this is explained by means of a non-local linear theory
 . In contrast to tokamak simulations and experiments\, but in agreemen
 t with edge measurements in W7-X [4]\, radial propagation of coherent 
 filamentary structures (blobs) is not observed\, revealing important d
 ifferences between stellarator and tokamak edge transport mechanisms.<
 br>
\n<br>
\n	We further present the first validation of a simulation 
 of plasma turbulence in a stellarator configuration against experiment
 al measurements in the TJ-K stellarator [5]. The comparison shows that
  GBS retrieves the main turbulence properties observed in the device\,
  namely the fact that transport is dominated by fluctuations with low 
 poloidal mode number.<br>
\n<br>
\n	Finally we present simulations in 
 a set of equilibria with increasing ellipticitiy and increasing torsio
 n generated by VMEC. The limit of zero ellipticity and zero torsion co
 rresponds to a tokamak with circular flux surfaces\, allowing to study
  edge turbulence in the transition between a tokamak and a stellarator
 .  The role of ellipticity and torsion as well as of magnetic shear is
  discussed.<br>
\n<br>
\n<br>
\n[1] P. Ricci et al.\, Plasma Physics a
 nd Controlled Fusion 54\, 124047 (2012)<br>
\n[2] W. Dommaschk\, Compu
 ter Physics Communications 40\, 203 (1986)<br>
\n[3] A. J. Coelho et a
 l\, Nuclear Fusion 62\, 074004 (2022)<br>
\n[4] C. Killer et al\, Plas
 ma Physics and Controlled Fusion 62\, 085003 (2020)<br>
\n[5] A. J. Co
 elho et al\, Plasma Physics and Controlled Fusion 65\, 085<br>
\n
URL:https://www.physics.wisc.edu/events/?id=8496
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