Development of KSTAR in-vessel components and heating systems

Yang, H.L.; Park, Y.M.; Bae, Y.S.; Kim, H.K.; Kim, K.M.; Lee, K.S.; Bang, Eunnam; Kim, H.T.; Lee, H.J.; Kwag, S.W.; Chang, Y.B.; Song, N.H.; Park, H.T.; Joung, M.; Kim, J.S.; Han, W.S.; Kwon, M.; Park, S.I.; Do, Heejin; Cho, Minsuk; Park, H.; Namkung, W.; Chang, Dae-Sik; Jeong, Seung-Ho; Jin, J.; Jhang, D.S.; Kwak, J.G.; Wang, S.J.; Kim, S.H.; Kim, S.K.; Bae, Y.D.

doi:10.1016/j.fusengdes.2011.02.083

Cited by 15 publications

(3 citation statements)

References 8 publications

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“…Along with the performance enhancement in various operating regimes, validation of critical physics and the study of improved stability and confinement of the plasma have been pursued, utilizing three unique features of KSTAR. They are a plasma with nearly perfect toroidal symmetry [4], a robust and versatile magnetic perturbation tool [5] and state-of-theart 2D/3D microwave imaging diagnostics [6,7]. The nearly perfect axisymmetry of the KSTAR plasma (a magnetic ripple of 0.04% and an error field of δB/B 0 ~ 1 × 10 −5 ) results in an extremely high toroidal rotation speed up to 0.8 M, where M is the Mach number, with a strong edge shear which may influence the confinement and stability of the plasma.…”

Section: Introductionmentioning

confidence: 99%

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

et al. 2019

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A decade-long operation of the Korean Superconducting Tokamak Advanced Research (KSTAR) has contributed significantly to the operation of superconducting tokamak devices and the advancement of tokamak physics which will be beneficial for the ITER and K-DEMO programs. Even with limited heating capability, various conventional as well as new operating regimes have been explored and have achieved improved performance. As examples, a long pulse high-confinement mode operation with and without an edge-localized mode (ELM) crash was well over 70 and 30 s, respectively. The unique capabilities of KSTAR allowed it to improve the capability of controlling harmful instabilities, and they have been instrumental in uncovering much new physics. The highlights are that the L/H transition threshold power is sensitive to the resonant magnetic perturbation (RMP) and insensitive to non-resonant magnetic perturbation. Co-Ip offset rotation dominated by an electron channel predicted by general neoclassical toroidal viscosity theory was confirmed. Improved heat dispersal in a divertor system using three rows of rotating RMP was demonstrated and predictive control of the ELM-crash with a priori modeling was successfully tested. In magnetohydrodynamic physics, validation of the full reconnection model (i.e. q0 > 1 right after the sawtooth crash) and self-consistent validation of the anisotropic distribution of turbulence amplitude and flow in the presence of the 2/1 island with theoretical models were achieved. The turbulence amplitude induced by RMP was linearly increased with the slow RMP coil current ramp-up time (i.e. the magnetic diffusion time scale). The Dα spikes (i.e. ELM-crash amplitude) was linearly decreased with the turbulence amplitude and not correlated with the perpendicular electron flow. In the turbulence area, a non-diffusive ‘avalanche’ transport event and the role of a quiescent coherent mode in confinement were studied. To accommodate the anticipation of a higher performance of the KSTAR plasmas with the increased heating powers, a new divertor/internal interface with a full active cooling system will be implemented after a full test of the new heating (neutral beam injection II and electron cyclotron heating) and current drive (CD) (Helicon and lower hybrid CD) systems. An upgrade plan for the internal hardware, heating systems and efficient CD system may allow for a long pulse operation of higher performance plasmas at βN > 3.0 with f bs ~ 0.5 and Ti > 10 keV.

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Section: Introductionmentioning

confidence: 99%

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

et al. 2019

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“…Most of the perturbation experiments have been carried out with high toroidal mode numbers (n > 2) due to fear that deeper penetration of the perturbed field at lower toroidal mode numbers (n = 1 or 2) could provide a seed for destabilizing internal MHD instabilities such as the sawtooth and NTMs in the core of the plasmas. The three rows of in-vessel control coils (IVCC) with n = 1 and/or n = 2 toroidal mode numbers are used for suppression of the 'ELM' on KSTAR [120]. 'ELM'-free H-mode operation of a plasma with a pulse length over~30 s was produced [121].…”

Section: What Are the New Findings In The Study Of Alfvén Mode Instabmentioning

confidence: 99%

“…Empirically the RMP has been very effective in suppression and/or mitigation of the ELM-crash as described in the previous section. For instance, predictive design of the operation window for the ELM-crash suppression based on the amplitude and phase of RMP coils [120] is quite encouraging but the recipe is not universal yet. The essence of this design suggests that the modeling has to account for the presence of the plasma in modeling of the RMP-induced suppression.…”

Section: What Are the New Findings In The Study Of Alfvén Mode Instabmentioning

confidence: 99%

Newly uncovered physics of MHD instabilities using 2-D electron cyclotron emission imaging system in toroidal plasmas

Park

2019

Advances in Physics: X

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Validation of physics models using the newly uncovered physics with a 2-D electron cyclotron emission imaging (ECEi) system for magnetic fusion plasmas has either enhanced the confidence or substantially improved the modeling capability. The discarded "full reconnection model" in sawtooth instability is vindicated and established that symmetry and magnetic shear of the 1/1 kink mode are critical parameters in sawtooth instability. For the 2/ 1 instability, it is demonstrated that the 2-D data can determine critical physics parameters with a high confidence and the measured anisotropic distribution of the turbulence and its flow in presence of the 2/1 island is validated by the modelled potential and gyro-kinetic calculation. The validation process of the measured reversed-shear Alfvéneigenmode (RSAE) structures has improved deficiencies of prior models. The 2-D images of internal structure of the ELMs and turbulence induced by the resonant magnetic perturbation (RMP) have provided an opportunity to establish firm physics basis of the ELM instability and role of RMPs. The importance of symmetry in determining the reconnection time scale and role of magnetic shear of the 1/1 kink mode in sawtooth instability may be relevant to the underlying physics of the violent kink instability of the filament ropes in a solar flare.

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Design and operation results of nitrogen gas baking system for KSTAR plasma facing components

Kim

Joung

et al. 2013

Fusion Engineering and Design

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Development of KSTAR in-vessel components and heating systems

Cited by 15 publications

References 8 publications

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

Overview of KSTAR research progress and future plans toward ITER and K-DEMO

Newly uncovered physics of MHD instabilities using 2-D electron cyclotron emission imaging system in toroidal plasmas

Design and operation results of nitrogen gas baking system for KSTAR plasma facing components

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