Fast-ion Dα spectroscopy diagnostic at KSTAR

Yoo, J. W.; Kim, Junghee; Lee, M. W.; Kang, Jisung; Ko, W. H.; Oh, Sungho; Ko, Jinseok; Lee, J. H.; Nam, Y. U.; Jung, L.; Park, B. H.; Yoon, S.W.

doi:10.1063/5.0040559

Cited by 10 publications

(6 citation statements)

References 15 publications

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“…The fast ion D-alpha (FIDA) diagnostic [25] confirms that the fast ion confinement is improved throughout the improved confinement phase under the 3D magnetic field. This is illustrated in the time trace of FIDA intensity signal at the core of plasma where R = 1.89 m in figure 5.…”

Section: Impact On Fast Ion Confinementmentioning

confidence: 80%

Observation of improved confinement by non-axisymmetric magnetic field in KSTAR

Kim

Kang

et al. 2023

Nucl. Fusion

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We report the observation of improved confinement discharge in the magnetic braking experiment in KSTAR tokamak. The improved confinement is achieved with reduced toroidal plasma rotation by non-axisymmetric magnetic field induced toroidal rotation braking along with significant reduction of ELMs.Modifications in multi-channel transport raise fast ion slowing-down time and improve neutral beam deposition, leading to improved fast ion confinement. We show that modifications of radial electric field and ExB shear flow by magnetic braking provoke enhanced pedestal to sustain thermal confinement against degradation in the typical 3D field experiment.

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Section: Impact On Fast Ion Confinementmentioning

confidence: 80%

Observation of improved confinement by non-axisymmetric magnetic field in KSTAR

Kim

Kang

et al. 2023

Nucl. Fusion

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“…The Motional Stark effect (MSE) diagnostic 65 is employed to extract the core current density pro le for the kinetic equilibrium construction. The properties of fast ions are diagnosed through the fast ion loss detector (FILD) 66 and the fast-ion D α (FIDA) 67…”

Section: Diagnosticsmentioning

confidence: 99%

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

Han

Park

Sung

et al. 2022

Nature

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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.

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“…Fast ion D α (FIDA) measurement [24] shows fast ion confinement is improved (or recovered) in the AE suppressed phase, as indicated by elevated FIDA intensity during the AE suppression period in figure 3(a). The FIDA intensity profiles before, during, and after the TAE suppression in figure 3(b) indicate the increase of the FIDA intensity in the whole plasma volume (R < 2.2 m).…”

Section: Experimental Observationsmentioning

confidence: 96%

Application of non-axisymmetric magnetic field for control of Alfvén eigenmodes in KSTAR

Kim,

Kang,

Rhee

et al. 2024

Nucl. Fusion

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We report the experimental examination of non-axisymmetric (3D) magnetic field for control of Alfvén eigenmodes (AEs) in KSTAR. Application of the phase-sweeping n=1 3D magnetic field identifies the effective 3D field phase and threshold amplitude for suppression of the toroidal Alfvén eigenmodes (TAE). Such observations indicate at least two conditions of 3D field phase and amplitude should be satisfied for the AE suppression. The phase window of AE suppression is largely resonant and thereby overlapped with that of mode locking, while the threshold of mode locking is slightly higher than that of AE suppression, which implies narrow 3D configuration window for AE suppression. Numerical analyses on the AE stability and fast ion phase-space transport suggest that key mechanism of the AE suppression is the reduction of the AE drive through redistribution of fast ion phase-space distribution by strong resonant interactions of the fast ions with the 3D magnetic field.

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Fast-ion Dα spectroscopy diagnostic at KSTAR

Cited by 10 publications

References 15 publications

Observation of improved confinement by non-axisymmetric magnetic field in KSTAR

Observation of improved confinement by non-axisymmetric magnetic field in KSTAR

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

Application of non-axisymmetric magnetic field for control of Alfvén eigenmodes in KSTAR

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