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

Abstract

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 Ti exceeding Te 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 Ti = Te. In addition to the decreases in collisionality and the increases in ion heating fraction in the discharges with high NBI power, Ti > Te can also be attributed to positive feedback between the high Ti/Te ratio and stabilisation of the turbulent heat flux resulting from the ion temperature gradient driven mode. The high Ti/Te 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 gasmore » puffing and pellet injection. Lastly, this reveals that particle fuelling played a key role for achieving high Ti/Te, and the improved fusion performance.« less

Authors:
 [1];  [2];  [3];  [3];  [3]; ORCiD logo [3];  [4];  [3];  [5];  [5]
  1. Culham Science Centre, Abingdon (United Kingdom). EUROfusion Programme Management Unit
  2. Culham Science Centre, Abingdon (United Kingdom). JET Exploitation Unit
  3. Culham Science Centre, Abingdon (United Kingdom). Culham Centre for Fusion Energy (CCFE)
  4. 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)
  5. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE; European Commission (EC)
Contributing Org.:
JET contributors
OSTI Identifier:
1432663
Grant/Contract Number:  
633053
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 3; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; JET-ILW; baseline scenario; Ti/Te; gas puffing; TRANSP; fusion performance

Citation Formats

Kim, Hyun-Tae, Sips, A. C. C., Romanelli, M., Challis, C. D., Rimini, F., Garzotti, L., Lerche, E., Buchanan, J., Yuan, X., and Kaye, S. High fusion performance at high Ti/Te in JET-ILW baseline plasmas with high NBI heating power and low gas puffing. United States: N. p., 2018. Web. doi:10.1088/1741-4326/aaa582.
Kim, Hyun-Tae, Sips, A. C. C., Romanelli, M., Challis, C. D., Rimini, F., Garzotti, L., Lerche, E., Buchanan, J., Yuan, X., & Kaye, S. High fusion performance at high Ti/Te in JET-ILW baseline plasmas with high NBI heating power and low gas puffing. United States. doi:10.1088/1741-4326/aaa582.
Kim, Hyun-Tae, Sips, A. C. C., Romanelli, M., Challis, C. D., Rimini, F., Garzotti, L., Lerche, E., Buchanan, J., Yuan, X., and Kaye, S. Thu . "High fusion performance at high Ti/Te in JET-ILW baseline plasmas with high NBI heating power and low gas puffing". United States. doi:10.1088/1741-4326/aaa582. https://www.osti.gov/servlets/purl/1432663.
@article{osti_1432663,
title = {High fusion performance at high Ti/Te in JET-ILW baseline plasmas with high NBI heating power and low gas puffing},
author = {Kim, Hyun-Tae and Sips, A. C. C. and Romanelli, M. and Challis, C. D. and Rimini, F. and Garzotti, L. and Lerche, E. and Buchanan, J. and Yuan, X. and Kaye, S.},
abstractNote = {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 Ti exceeding Te 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 Ti = Te. In addition to the decreases in collisionality and the increases in ion heating fraction in the discharges with high NBI power, Ti > Te can also be attributed to positive feedback between the high Ti/Te ratio and stabilisation of the turbulent heat flux resulting from the ion temperature gradient driven mode. The high Ti/Te 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 Ti/Te, and the improved fusion performance.},
doi = {10.1088/1741-4326/aaa582},
journal = {Nuclear Fusion},
number = 3,
volume = 58,
place = {United States},
year = {2018},
month = {2}
}

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Figures / Tables:

Figure 1 Figure 1: Measured neutrons against (a) NBI heating power, (b)ICRH power, (c) total heating power (NBI + ICRH). The red and black circles are the discharges with high neutron rates (>1e16#/sec) and low (<1e16#/sec) neutron rates, respectively. Please note, the red and black circles correspond to the discharges with themore » same symbols in Figure 2, Figure 3(a), Figure 4(a), and Figure 5(a)(b)(c)).« less

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