Speaker
Eva Macusova
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1019.pdf
Coupled Fokker-Planck and transport simulations of runaway electrons
in COMPASS
E. Macusova1 , J. Urban1 , O. Ficker1,2 , J. Mlynar1 , J. Decker3 , Y. Peysson4 ,
J. Cerovsky1,2 , M. Farnik1,2 , M. Hron 1 , R. Panek 1 , V. Weinzettl1 , M. Vlainic5 ,
the COMPASS team1 & the EUROfusion MST1 team ∗
1 Institute of Plasma Physics of the CAS, CZ-18200 Prague 8, Czech Republic
2 FNSPE, Czech Technical University in Prague, CZ-11519 Prague 1, Czech Republic
3 Swiss Plasma Centre, EPFL, CH-1015 Lausanne, Switzerland
4 CEA, IRFM, F-13108 Saint-Paul-lez-Durance, France
5 Institute of Physics, University of Belgrade, Belgrade, Serbia
∗ See the author list H. Meyer et al 2017 Nucl. Fusion 57 102014
An extensive study of discharges with the runaway electrons (RE) generation [J. Mlynar et
al. invited, EPS 2018] was performed within several dedicated campaigns at the COMPASS
tokamak [Panek et al. PPCF 2016]. The formation of the RE population and its dynamics are
strongly sensitive to the background plasma parameters (density, magnetic field, electric field,
impurity content etc.). Signals from RE related diagnostics at COMPASS such as HXR or neu-
tron detectors correspond to high energy RE losses. The low energy part of the RE population
and its losses are given by the ECE radiometer and the Cherenkov detector respectively. The lack
of direct measurement of the RE momentum distribution function motivates us to use sophis-
ticated numerical models as a complementary tool to obtain more comprehensive information
and insight. Presented RE simulations are based on coupling of the fast transport code METIS
[Artaud et al. NF 2010] and the 1D + 2V relativistic bounce-averaged kinetic Fokker-Planck
solver LUKE [Decker and Peysson, EUR-CEA-FC 2004]. The LUKE code includes avalanche
source of RE, radiation losses, fast particles radial transport with phase-space dependence and
trapping effect. The METIS-LUKE coupling allows us to calculate time and space resolved
electron distribution function and an improved evolution of plasma profiles. Plasma parameters
vary slowly in COMPASS quiescent and flat-top RE discharges. This makes them good candi-
dates for METIS-LUKE simulations which can give a better understanding of the RE related
physics. We demonstrate how METIS-LUKE simulations can reconstruct RE formation based
on available, indirect diagnostics, such as plasma current, loop voltage or electron temperature.
