Numerical study for design of the passive stabilizer and its impact on MHD stability in the proposed KSTAR plasma

Lee, D.-Y.; Chang, C. S.; Manickam, J.; Pomphrey, N.; Chance, M. S.; Jardin, S.C.

doi:10.1016/s0920-3796(99)00060-5

Cited by 5 publications

(1 citation statement)

References 21 publications

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“…Unfortunately, while enhancing plasma performance, increasing κ areal can also act to destabilize magneto-hydrodynamic (MHD) modes like the n = 0 resistive wall mode, which can trigger vertical displacement events (VDEs) and ultimately result in the violent termination of the plasma discharge. To avoid VDEs while still operating at the maximum achievable elongation, many tokamaks employ passive stabilization techniques [3][4][5][6] and/or active real-time control feedback loops [7][8][9][10][11][12][13][14] that work to prevent the uncontrolled growth of the vertical instability.…”

Section: Introductionmentioning

confidence: 99%

Implications of vertical stability control on the SPARC tokamak

Nelson,

Garnier,

Battaglia

et al. 2024

Nucl. Fusion

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To achieve its performance goals, SPARC plans to operate in equilibrium configurations with a strong elongation of κ areal ∼ 1.75 , which in turn will destabilize the n = 0 vertical instability. However, SPARC also features a relatively thick conducting wall that is designed to withstand disruption forces, leading to lower vertical instability growth rates than usually encountered. In this work, we use the TokSyS framework to survey families of accessible shapes near the SPARC baseline configuration, finding maximum growth rates in the range of γ ≲ 100 s−1. The addition of steel vertical stability plates has only a modest ( ∼ 25 % ) effect on reducing the vertical growth rate and almost no effect on the plasma controllability when the full vertical stability system is taken into account, providing flexibility in the plate conductivity in the SPARC design. Analysis of the maximum controllable displacement on SPARC is used to inform the power supply voltage and current limit requirements needed to control an initial vertical displacement of 5% of the minor radius. From the expected spectra of plasma disturbances and diagnostic noise, requirements for filter latency and vertical stability coil heating tolerances are also obtained. Small modifications to the outboard limiter location are suggested to allow for an unmitigated vertical disturbance as large as 5% of the minor radius without allowing the plasma to become limited. Further, investigations with the 3D COMSOL code reveal that strategic inclusion of insulating structures within the VSC supports are needed to maintain sufficient magnetic response. The workflows presented here help to establish a model for the integrated predictive design for future devices by coupling engineering decisions with physics needs.

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