| Contributors: |
B, Lomanowski; M, Dunne; N, Vianello; S, Aleiferi; M, Brix; J, Canik; Is, Carvalho; L, Frassinetti; D, Frigione; L, Garzotti; M, Groth; A, Meig; S, Menmuir; M, Maslov; T, Pereira; Cp, von Thun; M, Reinke; D, Refy; F, Rimini; G, Rubino; Pa, Schneider; G, Sergienko; A, Uccello; D, Van Eester; Mailloux, J.; Abid, N.; Abraham, K.; Abreu, P.; Adabonyan, O.; Adrich, P.; Afanasev, V.; Afzal, M.; Ahlgren, T.; Aho-Mantila, L.; Aiba, N.; Airila, M.; Akhtar, M.; Albanese, R.; Alderson-Martin, M.; Alegre, D.; Aleiferis, S.; Aleksa, A.; Alekseev, A. G.; Alessi, E.; Aleynikov, P.; Algualcil, J.; Ali, M.; Allinson, M.; Alper, B.; Alves, E.; Ambrosino, G.; Ambrosino, R.; Amosov, V.; Andersson Sunden, E.; Andre, P.; Angelini, B. M.; Angioni, C.; Antoniou, I.; Appel, L. C.; Appelbee, C.; Aria, S.; Ariola, M.; Artaserse, G.; Arter, W.; Artigues, V.; Asakura, N.; Ash, A.; Ashika a, N.; Aslanyan, V.; Astrain, M.; As talos, O.; Auld, D.; Auriemma, F.; Austin, Y.; Avotina, L.; Aymerich, E.; Baciero, A.; Bairaktaris, F.; Balbin, J.; Balbinot, L.; Balboa, I.; Balden, M.; Balsha, C.; Balsha, N.; Bandaru, V. K.; Banks, J.; Baranov, Yu. F.; Barcellona, C.; Barnard, A.; Barnard, M.; Barnsley, R.; Barth, A.; Baruzzo, M.; Barwell, S.; Bassan, M.; Batista, A.; Batistoni, P.; Baumane, L.; Bauvir, B.; Baylor, L. |
| Description: |
Changes in global and edge plasma parameters (H (98(y,2)), dimensionless collisionality nu *, core density peaking, separatrix density n (e,sep)) with variations in the D-2 fueling rate and divertor configuration are unified into a single trend when mapped to ⟨T (e,ot)⟩, the spatially averaged spectroscopically derived outer target electron temperature. Dedicated JET with the ITER-like wall (JET-ILW) experiments in combination with an extended JET-ILW database of unseeded low-triangularity H-mode plasmas spanning a wide range of D-2 fueling rates, I (p), B (t) and heating power have demonstrated the importance of ⟨T (e,ot)⟩ as a key physics parameter linking the recycling particle source and detachment with plasma performance. The remarkably robust H (98(y,2)) trend with ⟨T (e,ot)⟩ is connected to a strong inverse correlation between ⟨T (e,ot)⟩, n (e,sep) and nu *, thus directly linking changes in the divertor recycling moderated by ⟨T (e,ot)⟩ with the previously established relationship between nu *, core density peaking and core pressure resulting in a degradation in core plasma performance with decreasing ⟨T (e,ot)⟩ (increasing nu *). A strong inverse correlation between the separatrix to pedestal density ratio, n (e,sep)/n (e,ped), and ⟨T (e,ot)⟩ is also established, with the rise in n (e,sep)/n (e,ped) saturating at ⟨T (e,ot)⟩ > 10 eV. A strong reduction in H (98(y,2)) is observed as ⟨T (e,ot)⟩ is driven from 30 to 10 eV via additional D-2 gas fueling, while the divertor remains attached. Consequently, the pronounced performance degradation in attached divertor conditions has implications for impurity seeding radiative divertor scenarios, in which H (98(y,2)) is already low (similar to 0.7) before impurities are injected into the plasma since moderate gas fueling rates are required to promote high divertor neutral pressure. A favorable pedestal pressure, p (e,ped), dependence on I (p) has also been observed, with an overall increase in p (e,ped) at I (p) = 3.4 MA as ⟨T (e,ot)⟩ is driven down from ... |