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SUMMARY:Realistic multi-machine tokamak profile simulations and numerical 
 ramp-down optimization using the RAPTOR code
DTSTART:20180423T103000
DTEND:20180423T113000
DTSTAMP:20260407T230539Z
UID:1e2af1bbf86ebc0e631b52e4c868cfe5b70e1e2885eb616e26e694a8
CATEGORIES:Conferences - Seminars
DESCRIPTION:Dr. A. Teplukhina\, SPC-EPFL  \nPredictive modelling of plas
 ma profiles is an essential part of ongoing research in tokamak plasmas\, 
 required for a successful realization of future fusion reactors. In this r
 esearch we focus on upgrading the RAPTOR code to extend the area of its ap
 plicability for plasma modelling and scenario development and also demonst
 rate new strategy for ramp-down optimization. The RAPTOR transport model h
 as been extended to take into account the influence of the time-varying pl
 asma equilibrium geometry and background kinetic profiles on the evolution
  of the predicted plasma profiles. Also transport equations for the ion te
 mperature and plasma particles (electrons and ions) have been implemented 
 in the code. Benchmarks have been performed with more sophisticated transp
 ort ASTRA and CRONOS codes and with prescribed data for the particle trans
 port in ITER. A new ad-hoc transport model based on constant gradients for
  core and pedestal regions\, that is suitable for simulations of transitio
 n between H and L modes\, has been implemented into RAPTOR. This model ass
 umes ``stiffness'' of the plasma profiles in the core region\, reflecting 
 their relatively weak reaction to changes in the heat flux. We demonstrate
  the capabilities of RAPTOR for realistic predictions of plasma state over
  the entire plasma discharges\, i.e. from ramp-up to ramp-down\, for TCV\,
  ASDEX Upgrade and JET plasmas.\nAutomatic optimization algorithms can be 
 applied for searching the optimal ramp-down trajectory. Here we define the
  goal of the optimization as ramping down the plasma current as fast as po
 ssible while avoiding any disruptions caused by reaching physical or techn
 ical limits. Physical constraints are relevant for most tokamaks\, others 
 are technical and related to the specific tokamaks. A proper plasma shapin
 g during the current ramp-down can reduce significantly the plasma interna
 l inductance\, improving its vertical stability. Results of numerical and 
 experimental ramp-down studies for TCV\, AUG and JET plasmas are presented
 .
LOCATION:ppb 019
STATUS:CONFIRMED
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