Integration of X-Point Radiator Divertor Operation with High Beta Core Plasmas in DIII-D

Recent DIII-D experiments have demonstrated the compatibility of complete divertor detachment with a high beta core plasma by using both hybrid and high-poloidal-beta scenario approaches. In both cases the radiation peaks inside the X-point, indicating achievement of the X-Point Radiator (XPR) regime. For the high beta hybrid, shallow XPR with complete divertor detachment and high beta (β_N ~3.0, H₉₈~1.25) have been simultaneously achieved using an ITER-similar shape and N2 seeding. However, this plasma remains ELMing with giant ELMs with ~10% energy loss. With stronger N₂ puffing, the plasmas exhibit a deep XPR regime with 2x core radiation peaking at the pedestal, the ELMs are strongly mitigated, and the confinement is significantly reduced to H₉₈<1.0. With the high-bp approach, XPR, ELM suppression and a high beta core were achieved by optimizing neon seeding. Confinement is maintained with an enhanced ITB compensating the potential performance degradation from the weaker pedestal. In addition, the neon injection leads to an increase of ~20% in ion temperature profiles. Stability analysis confirms that pedestal peeling-ballooning modes are stable in this non-ELM regime. Furthermore, the good compatibility between complete detachment and high-beta core has also been demonstrated with the outer strike point positioned on the tungsten-coated tile of the SAS-VW divertor, highlighting the potential for using this approach to solve the core-edge integration with a reactor-relevant wall material.