DIVIMP simulations of 13C puffing experiments in ASDEX Upgrade L-mode plasma

Abstract

Carbon migration has been investigated both experimentally and numerically by injecting isotopically marked methane ( 13 CH 4 ) at trace levels into a series of identical low-density, low-confinement mode discharges at the last day of the 2007 ASDEX Upgrade experimental campaign. The experiment is simulated with the DIVIMP code to test which assumptions are needed to reproduce the observed deposition pattern. Including a realistic poloidal flow profile was observed to be crucial in replicating the experimental results.

The effect of non-axisymmetric wall geometry on 13C transport in ASDEX Upgrade

“…A reasonable match with the experimental results was found when a manually imposed deuteron flow field corresponding to these experimental observations was used, following the approach first presented in [8] and [9]. The DIVIMP modelling is described in more detail in [5].…”

“…The previous DIVIMP simulations were used as a basis for the ASCOT modelling [5]. The background plasma solution from the DIVIMP OSM solver for the discharge #22575 was used for the scrape-off layer (SOL) plasma, excluding the plasma flow field.…”

“…Near the outer midplane, protruding wall structures such as port and ICRH limiters collect substan- Table 1. Comparison between the 2007 experiment [1] and ASCOT and DIVIMP [5] simulations of large-scale 13 C deposition. In the first row, the measured deposition, assuming toroidal symmetry, is normalized to the amount of injected 13 C. In the second row, the deposition is normalized to the amount of found 13 C with excluding the uncertain deposition at the top of the vessel.…”

Global migration of 13C impurities in high-density L-mode plasmas in ASDEX Upgrade

“…Modelling of the 2011 injection experiment was initiated by simulating the background plasma with the 2D plasma fluid code SOLPS. The main aim was to obtain a range of background plasmas for simulations with ASCOT and a prediction for the poloidal flow profile as this has been noticed to have a significant influence on the simulated deposition distribution for 13 C [6,7].…”

“…AUG, being a full-W device [5] since 2007, is an ITER-relevant environment for such studies, and so far five global injection experiments have been realized there [4]. In addition to the experiments, attention has been paid to modelling the observed deposition patterns with the ASCOT [6], DIVIMP [7], and SOLPS [8] codes. This article gives an overview of the 2011 experiment and the 13 C results as well as the status of the recent modelling efforts with SOLPS and ASCOT.…”