Speaker
Doohyun Kim
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1003.pdf
Modeling of sawtooth-induced fast particle redistribution in
NSTX-U
D. Kim , D. Liu , M. Podestà and F.M. Poli ,
1 2 1 1
Princeton Plasma Physics Laboratory, Princeton, NJ 08543, USA
1
2
Department of Physics and A stronomy, University of California, Irvine, CA 92617, USA
The effects of sawtooth on fast ion transport have been studied in L-mode sawtoothing
discharges during the 2016 experimental campaign on National Spherical Torus Experiment
Upgrade (NSTX-U) [1]. Experimental observations show that passing particles are strongly
redistributed from the plasma core to the edge, while trapped particles are weakly affected by
sawteeth [2]. TRANSP [3] simulations using the implemented standard sawtooth models can
reproduce the experimental neutron rate drops with a proper parameter set. However, since
the different effect of sawtooth crash on fast ions with different orbit type and energy is not
taken into account in the sawtooth model, detailed simulation results do not agree with the
experimental measurement. Therefore a more comprehensive and improved model for
quantitative simulations needs to be developed including the characteristics of fast ion so that
more reliable interpretation of sawtoothing discharges can be possible. As a first step of the
development of the improved sawtooth model, simulations using the ORBIT code [4] have
been carried out [5]. The simulation results confirm the experimental observation that fast
ions are redistributed by sawtooth crash based on their orbit type and energy. In real space,
due to a sawtooth crash passing particles in the core region are expelled and move outside the
q=1 surface while a sawtooth crash does not have significant effects on trapped particles. The
initial TRANSP simulation using the kick model [6] based on the ORBIT modeling result
shows improvement of fast ion redistribution before and after a sawtooth crash but more
simulations are required as the neutron rate still has discrepancy compared to the
experimental measurement.
This work is supported by the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences
under contract number DE-AC02-09CH11466.
References:
[1] Battaglia D.J. et al., accepted to Nucl. Fusion (2018)
[2] Liu D. et al., submitted to Nucl. Fusion (2017)
[3] Hawryluk R. An empirical approach to tokamak transport Physics Close to Thermonuclear Conditions vol 1
ed B. Coppi et al. (Brussels: Commission of the European Communities) p 19. (1980)
[4] White R.B. and Chance, M.S. Phys. Fluids 27 (1984) 2455
[5] Kim D., Podestà M., Liu D. and Poli F.M., submitted to Nucl. Fusion (2018)
[6] Podestà M., Gorelenkova M. and White R.B., Plasma Phys. Control. Fusion, 56 (2014) 055003
