Investigating highly dissipative X-Point Target scenarios for SPARC using SOLEDGE3X-EIRENE

One objective of SPARC tokamak experiments is to identify high-dissipation divertor scenarios for the ARC FPP. The X-Point Target (XPT) alternative configuration, featuring a long-legged divertor and a secondary X-point within the divertor volume, offers key advantages: radiation localization in the divertor, increased plasma-wetted area, reduction of the electron temperature at the targets for fixed upstream power fluxes and density [1,2]. The present study utilizes the full domain edge code SOLEDGE3X-EIRENE in 2D mode to compare two potential SPARC XPT configurations, Connected Double Null (CDN) and Disconnected Double Null. All cases are in H-mode condition, with B_T=12T, I_p=5.0 MA, P_SOL=17MW and n_GW=0.3, values consistent with the SPARC-ARC overlap space for SOL-similarity metric [4]. Results in pure Deuterium show that at the same conditions, the XPT CDN exhibits lower target temperatures (T_e,ot∼130eV) than other cases (T_e,ot∼360-200eV) and feasible heat fluxes (10MW/m²). Moreover, XPT CDN shows reversed flows due to high recycling at the outer target, which significantly impacts the impurity SOL distribution [3]. The study is extended to the use of Neon as the primary radiator to investigate the XPT configurations in detached scenarios.

Supported by Commonwealth Fusion Systems.



[1] Lee K. et al, Phys. Rev. Lett. (2025)

[2] Umansky M.V. et al, NME (2017)

[3] Krasheninnikov S.I. et al, NF (1992)

[4] Wigram M.R.K. et al, Poster SOFE (2025)