2024 – Steady-state hybrid scenario with Tungsten radiation and control strategies for KSTAR long pulse operation

Steady-state hybrid scenario with Tungsten radiation and control strategies for KSTAR long pulse operation

2024 Research Campaign, Task Force: W Compatible Steady State Scenarios

Purpose of Experiment

This experiment has two aspects, that connect DIII-D and KSTAR in developing a successful steady-state scenario with various levels of Tungsten radiation, and devising strategies to mitigate the impurity and radiation issues. A synergistic aspect that aims at projecting these results to ITER and FPP regimes is included by utilizing W-equivalent radiators to compare the results to higher temperature machines, and correctly project forward.

Experimental Approach

The first goal is to adapt the SN hybrid steady-state scenario developed in DIII-D, which operates at q95~5-6, betaN~2.8-3, in a LSN shape, at density~3.5e10, to a scaled KSTAR shape (still LSN), or preferably to an ITER shape (depending on results from day 1). Modifications to the existing DIII-D scenario to react to the different trajectories will be the subject of the first part of the experiment. The second aspect is to assess which mitigation strategies work best and how they impact the scenario, under a variety of conditions that are compatible with KSTAR parameters. ECH power will use used primarily in the optimal location from the start, if time permits it will be moved to rho=0.4 to assess the differences. A parallel goal is to compare the Tungsten radiation to the W-equivalent impurities that are more relevant for mimicking the Tungsten impact in higher temperature machines such as ITER and FPP. This is necessary to correctly extrapolate the DIII-D and KSTAR results in this scenario to the fusion reactors our machines are tasked to prepare for. The Kr and Xe elements have the same radiative loss rate (Lz) at DIII-D’s and KSTAR temperatures, as W has in ITER and FPP-type scenarios, so the use of these radiators directly addresses the physics of W in ITER and FPP core plasmas. The data comparing W and Kr/Xe will greatly improve the fidelity of the integrated modelling codes that are necessary to make the KSTAR and DIII-D plasmas meaningful step-stones toward future reactors.

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