High gas throughput SOLPS-ITER simulations extending the ITER database to strong detachment

Abstract

SOLPS-ITER simulations performed for $Q_{DT}$ = 10, $P_{SOL}$ = 100 MW burning plasmas on ITER extend the existing database to high values of separatrix averaged neon impurity concentration ($\cne$ $\approx$ 6\%) and divertor neutral pressure ($\pdiv$ $>$ 25 Pa) in order to determine the heat flux mitigation capability of these scenarios and whether strongly detached states are accessible. In the existing database of ITER simulations, the level of detachment was limited to cases where the integral ion flux to the outer target was greater than 80\% of the value at rollover, with the impurity radiation localized near the target. With the possibility of narrow heat flux channels and increased deposited power due to tile shaping, it is important to explore operation at a higher degree of detachment. Two series of simulations were explored to extend the database of SOLPS simulations. By increasing the deuterium and neon puff rates proportionally, the peak divertor energy flux ($\qpm$) is decreased from 5 to 3 $\mathrm{MW/m^2}$ while $\pdiv$ increased from 11 to 27 Pa. By increasing only the neon puff, $q_{\perp,max}$ can be reduced to $\mathrm{< 1 MW/m^2}$ while $\pdiv$ is maintained at $\sim 11$ Pa. As the neon puff level is increased, the position of the impurity radiation peak is shifted towards the X-point. At the highest neon puff levels with steady-state solutions, the electron temperature is reduced below 1 eV across 50 cm of each divertor target. The new cases extend previously observed tight relationships in power and momentum loss factors to low electron temperature.

A reduced model for the ITER divertor based on SOLPS solutions for ITER Q = 10 baseline conditions: A. identifying options for the control parameters*

“…This was done in order to determine the heat flux mitigation capability of these scenarios and whether strongly detached states are accessible. It was shown that (1 − f mom ) and (1 − f cool ) continue to be strongly correlated functions of T e,t , figure 10 of [16], even under the high impurity concentration and divertor pressure conditions; they also follow the extrapolated numerical fits reported here quite closely.…”

“…One is free to extrapolatively project, of course. This has very recently been done using new SOLPS-ITER simulations performed for Q DT = 10, P SOL = 100 MW burning plasmas on ITER that extend the database used here to high values of separatrix averaged neon impurity concentration ( c Ne ≈ 6%) and divertor neutral pressure ( p div > 25 Pa) [16]. This was done in order to determine the heat flux mitigation capability of these scenarios and whether strongly detached states are accessible.…”

Density pedestal prediction model for tokamak plasmas

“…Separating the data according to the divertor configuration and using a different dependence on the gas rate for each configuration improves the fit slightly. This indicates that the pumping efficiency is different for different divertors as is shown experimentally in [30] and points to the need for scrapeoff layer modelling with a code like SOLPS [31] for a truly physics based prediction of n e,sep .…”

Coupled KIPP-EDGE2D modeling of parallel transport in the SOL and divertor plasma for the ITER baseline scenario

“…Plasmas with an enhanced radiation from divertors may, however, also be reactor relevant. Highly radiative SOLPS-ITER runs were recently carried out in the study [14] aiming at exploring ITER operation at a higher degree of detachment. In this study, by increasing D and Ne puff rates proportionally, the peak divertor energy flux decreased from 5 to 3 MW m −2 , with the position of the impurity radiation peak shifting towards the X-point.…”