Measurements and ERO simulations of carbon flows in the high-field side main SOL in AUG

Abstract

The plasma flow in the SOL is important for impurity migration. There are few measurements from the HFS main SOL. To study the flow in the HFS SOL of ASDEX Upgrade, methane was injected from a HFS valve. The ensuing carbon emission distribution was followed using a fast video camera and a spectrometer was used to determine the Doppler shift of the injected carbon. This was carried out in lower single null L-mode and H-mode for low and high density plasmas. To elucidate the coupling between the flow of the injected carbon and the actual deuterium flow, ERO simulations were utilized. A strong carbon and deuterium flow towards the lower inner divertor was observed for high density plasmas in the far SOL along with a shear in the flow profile.

Synthetic Doppler spectroscopy and curvilinear camera diagnostics in the ERO code

“…ERO was able to reproduce the experimental measurements for lineintegrated emission and flow velocity for both CII and CIII using realistic values for the background [9]. However, the temperature was not matched.…”

“…As discussed in the introduction, ERO simulations with these synthetic diagnostics were used to interpret methane injection experiments in AUG [9]. Several similar discharges were carried out with methane injection in the HFS SOL.…”

“…The synthetic data in figures 4, 5, 6, and 7 is from one ERO simulation. The agreement between experimental and synthetic data is good, but it required careful optimization of the plasma profiles (density, temperature, and flow velocity) used in the ERO simulation [9]. Therefore, this cannot be considered a benchmark of the ERO code or the new diagnostics.…”

“…The experimental setup is shown in figure 1. These experiments are reported in [9]. It should be noted that the spectrometer observes a line-integrated signal.…”

“…These diagnostics were designed to replicate the diagnostics shown in figure 1 but are also easily transferred to another setup. This paper describes the new synthetic diagnostics, cites results where they are used for interpreting the experiment described above [9], and explores the importance of 3D effects for this particular case.…”