A sustained high-temperature fusion plasma regime facilitated by fast ions

Abstract

We report a discovery of a fusion plasma regime suitable for commercial fusion reactor where the ion temperature was sustained above 100 million degree about 20 s for the rst time. Nuclear fusion as a promising technology for replacing carbon-dependent energy sources has currently many issues to be resolved to enable its large-scale use as a sustainable energy source. State-of-the-art fusion reactors cannot yet achieve the high levels of fusion performance, high temperature, and absence of instabilities required for steady-state operation for a long period of time on the order of hundreds of seconds. This is a pressing challenge within the eld, as the development of methods that would enable such capabilities is essential for the successful construction of commercial fusion reactor. Here, a new plasma con nement regime called fast ion roled enhancement (FIRE) mode is presented. This mode is realized at Korea Superconducting Tokamak Advanced Research (KSTAR) and subsequently characterized to show that it meets most of the requirements for fusion reactor commercialization. Through a comparison to other well-known plasma con nement regimes, the favourable properties of FIRE mode are further elucidated and concluded that the novelty lies in the high fraction of fast ions, which acts to stabilize turbulence and achieve steady-state operation for up to 20 s by self-organization. We propose this mode as a promising path towards commercial fusion reactors.

Progress in the development and understanding of a high poloidal-beta tokamak operating scenario for an attractive fusion pilot plant

“…The reference (Litaudon 2006) summarizes several approaches or physical mechanisms that could be responsible for ITB formation. In addition to that, recent studies from both modeling and experiment indicate that fast ions can also play an important role in turbulence suppression and ITB development (Citrin et al 2013;Di Siena et al 2021;Han et al 2022).…”

Tailoring error field of tokamak to control plasma instability and transport

“…Furthermore, ERMP maintains an advanced plasma regime with improved core confinement at a reactor-relevant ion temperature of 100 million kelvin by regulating edge transport of tokamak plasmas. These results show that tailoring the n = 1 EF of the tokamak is a promising new direction to control the stability and transport of tokamaks, with the potential to improve any high-performance tokamak scenario (H-mode [30,31], I-mode [32], FIRE mode [33], negative triangularity [34,35] L-mode) to accelerate fusion science.…”

“…6. The target discharge is an I-mode scenario in KSTAR, and it has improved core confinement with a core ion temperature up to 10 keV [33]. However, the improved core confinement is difficult to sustain without ERMP and vanishes with the further development of ETB.…”

Temperature separation under compression of moderately coupled plasma

“…2015; Han et al. 2022). Temperature separation can have a substantial impact on plasma properties including pressure, heat capacity, fast particle stopping power and driver–target coupling, which significantly affect the fusion yield in a system near ignition (Rinderknecht et al.…”