Speaker
Ray Chandra
Description
See the full Abstract at http://ocs.ciemat.es/EPS2018ABS/pdf/P1.1030.pdf
Numerical modelling of detached plasma experiments with differential
pumping in Magnum-PSI
R. Chandra1 , G. R. A. Akkermans1 , I. G. J. Classen1 , R. Perillo1 ,
H. J. de Blank1 , P. Diomede1 , E. Westerhof1
1 DIFFER - Dutch Institute for Fundamental Energy Research, Eindhoven, The Netherlands
Sufficient decrease of plasma pressure, ion and heat flux along the scrape-off layer of a toka-
mak fusion reactor are imperative to ensure the survival of the divertor tiles. This specific con-
dition, defined as detachment, occurs within low temperature, high density, highly recycling
plasma that can also be realized in linear plasma devices such as Magnum-PSI [1]. In Magnum-
PSI, high recycling is achieved by utilizing differential pumping across three vacuum chambers.
Experiments have been conducted to mimic detachment in the Magnum-PSI linear device by
varying the neutral background pressure at the chamber of the recycling target via H2 gas puff-
ing [2], while the hydrogen plasma source parameters are kept constant across the experiments.
Numerical modelling is carried out to help gain further insights regarding the physics behind
detachment.
The experiments are benchmarked with a coupled fluid-kinetic approach using the B2.5- EU-
NOMIA code package [3]. EUNOMIA is a Monte Carlo neutral simulation optimized for linear
geometry. Thomson scattering measurements without gas puffing are used as a plasma bound-
ary condition at the source in the simulation, and the gas pressure in the target chamber will
be varied. The resulting electron density and temperature simulated profiles near the target are
compared with profiles measured in experiments. This paper presents the result of the bench-
mark tests, and identifies the collisional processes and other physical effects relevant to the
detached plasma state.
References
[1] H. J. N. van Eck et al., Plasma Sources Science and Technology 20, 4 (2011)
[2] I. Classen et al., Abstract, 59th Annual Meeting of the APS Division of Plasma Physics,
http://meetings.aps.org/link/BAPS.2017.DPP.PP11.77 (2017)
[3] R. C. Wieggers et al., Contributions to Plasma Physics, 52(5-6):440-444 (2012)
