High fusion performance at high Ti/Te in JET-ILW baseline plasmas with high NBI heating power and low gas puffing

Kim, Hyun-Tae; Sips, A. C. C.; Romanelli, M.; Challis, C. D.; Rimini, F.; Garzotti, L.; Lerche, E.; Buchanan, J.; Yuan, X.; Kaye, S.

doi:10.1088/1741-4326/aaa582

Title: High fusion performance at high T_i/T_e in JET-ILW baseline plasmas with high NBI heating power and low gas puffing

Journal Article · 01 February 2018 · Nuclear Fusion

DOI: https://doi.org/10.1088/1741-4326/aaa582 · OSTI ID:1432663

Kim, Hyun-Tae ^[1]; Sips, A. C. C. ^[2]; Romanelli, M. ^[3]; Challis, C. D. ^[3]; Rimini, F. ^[3];

^[3]; Lerche, E. ^[4]; Buchanan, J. ^[3]; Yuan, X. ^[5]; Kaye, S. ^[5]

Culham Science Centre, Abingdon (United Kingdom). EUROfusion Programme Management Unit
Culham Science Centre, Abingdon (United Kingdom). JET Exploitation Unit
Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE)
Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE); Lab. for Plasma Physics of the Ecole Royale Militaire / Koninklijke Militaire School (LPP-ERM/KMS), Brussels (Belgium)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

This article presents the transport analysis of high density baseline discharges in the 2016 experimental campaign of the Joint European Torus with the ITER-Like Wall (JET-ILW), where a significant increase in the deuterium–deuterium (D–D) fusion neutron rate (~2.8 × 10¹⁶ s^-1) was achieved with stable high neutral beam injection (NBI) powers of up to 28 MW and low gas puffing. Increase in T_i exceeding T_e were produced for the first time in baseline discharges despite the high electron density; this enabled a significant increase in the thermal fusion reaction rate. As a result, the new achieved record in fusion performance was much higher than the previous record in the same heating power baseline discharges, where T_i = T_e. In addition to the decreases in collisionality and the increases in ion heating fraction in the discharges with high NBI power, T_i > T_e can also be attributed to positive feedback between the high T_i/T_e ratio and stabilisation of the turbulent heat flux resulting from the ion temperature gradient driven mode. The high T_i/T_e ratio was correlated with high rotation frequency. Among the discharges with identical beam heating power, higher rotation frequencies were observed when particle fuelling was provided by low gas puffing and pellet injection. Lastly, this reveals that particle fuelling played a key role for achieving high T_i/T_e, and the improved fusion performance.

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Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: USDOE; European Commission (EC)

Contributing Organization:: JET contributors

Grant/Contract Number:: 633053

OSTI ID:: 1432663

Journal Information:: Nuclear Fusion, Vol. 58, Issue 3; ISSN 0029-5515

Publisher:: IOP ScienceCopyright Statement

Country of Publication:: United States

Language:: English

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Cited by: 29 works

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