Page 8 - Achievement of Field-Reversed Configuration Plasma Sustainment via 10 MW Neutral-Beam Injection on the C-2U Device

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positive correlation between electron temperature and energy confinement time. Our power- balance analysis, detailing loss channel characteristics and plasma timescales, shows substantial improvements in equilibrium and transport parameters. Previously reported Te scaling of the confinement time from C-2 experiment [see Fig. 27 in Ref. 4], τE,e ∝ Te1.6 where τE,e is electron energy confinement time, still continues at the higher electron temperature range in C-2U. This very attractive scaling result, paired with the considerable accomplishment of plasma sustainment obtained in C-2U, may lead to intriguing possibilities for possible future FRC-based fusion reactors.
4. Summary
The C-2U experimental program commenced with various key system upgrades from C-2, which include increased total NB input power to ~10+ MW (15 keV hydrogen, higher current at reduced beam energy), tilted injection angle and enhanced edge-biasing capability for boundary/stability control. The upgraded NBI system enabled significant plasma performance advances and had a profound impact on C-2U performance: e.g. reduction of peripheral fast- ion losses; increased core heating; rapidly established dominant fast-ion pressure; better NB plasma coupling with reduced shine-through losses; and current drive. Under optimum C- 2U operating conditions, plasma sustainment for ~5+ ms was successfully achieved, in which the performance is limited only by hardware and stored energy constraints such as the NBs’ pulse duration and the current sourcing capability of the end-on plasma guns.
Acknowledgments
The authors wish to thank the entire TAE Team for their dedicated work and effort on the C- 2U project, our Budker Institute colleagues for many key contributions to our experiment and beam development, and our shareholders who made this exciting research effort possible.
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