First tungsten radiation studies in DIII-D’s ITER baseline demonstration discharges

Abstract

ITER Baseline Scenario plasmas were studied in DIII-D using krypton and xenon gases as a proxy for the tungsten that will be present in ITER. These impurities were chosen for having the same radiative loss rate Lz as tungsten would exhibit in the hotter ITER core. Results show that the scenario with these core radiators spans the range of impurity concentration and W radiated fraction expected for ITER, and up to 50% higher values, explored at zero injected torque, as well as 1 Nm and full co-torque injection with T ∼ 3 Nm. Stationary discharges with duration >2–4 τR are achieved with f rad ⩾ 30% leading to a reduction in confinement of ∼10%, and a comparison with real metal radiators in the same range of f rad shows that the higher Lz at the lower temperatures in these plasmas yields too pessimistic results on the survivability and performance of this scenario in ITER. Simulations of ITER power balance including W radiation show that with concentration up to three times higher than in the DIII-D plasmas the scenario can be stationary, remaining at acceptable core radiated fraction values.

Radiation induced non-linear oscillations in ITER baseline scenario plasmas in DIII-D

“…A series of experiments carried out in this scenario, with a scan of Kr and Xe injection rates performed on the β N flattop of IBS demonstration discharges, to explore the impact of Tungstenequivalent radiators in the IBS. The Kr and Xe flow scans were performed at T = 0, 1 Nm and full co-torque injection, (yielding ∼3-3.5 Nm) obtaining a variety of radiated fraction values and MHD stability regimes [11]. Representative examples of the Kr flow scan are reported in figure 2, for a control case without impurity injection (black), one Kr injection and one Xe injection case with intermediate flow values (red and blue).…”