Overview of the KSTAR vacuum pumping system

Kim, K.P.; Lee, K.S.; Yang, H.L.; Kim, M.K.; Kim, H.K.; Kim, K.M.; Kim, H.T.; Kim, K.H.; Park, M.K.; Oh, Y.K.; Bak, J.S.

doi:10.1016/j.fusengdes.2008.12.064

Cited by 8 publications

(1 citation statement)

References 3 publications

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“…The reactions used in EIRENE are listed in table 1. The pumping surface is set to be the highlighted region in figure 3(a) for numerical simplicity, instead of extending the grid to the end of the port similar to the real geometry on KSTAR [15]. The simulation pumping surface is toroidally extended and the total area is 5.5 m 2 with the absorption probability set to be 0.2.…”

Section: Setup Of Solps-iter Simulationsmentioning

confidence: 99%

Atomic processes leading to asymmetric divertor detachment in KSTAR L-mode plasmas

Park¹,

Groth²,

Pitts³

et al. 2018

Nucl. Fusion

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Atomic processes leading to asymmetric divertor detachment in KSTAR L-mode plasmas. Nuclear Fusion, 58(12), [126033]. https://doi. AbstractThe experimentally observed in/out detachment asymmetry in KSTAR L-mode plasmas with deuterium (D) fueling and carbon walls has been investigated with the SOLPS-ITER code to understand its mechanism and identify important atomic processes in the divertor region. The simulations show that the geometrical combination of a vertical, inner target with short poloidal connection from X-point to target and a much longer outer divertor leg on an inclined target lead to neutral accumulation towards the outer target, driving outer target detachment at lower upstream density than is required for the inner target. This is consistent with available Langmuir probe measurements at both target plates, although the inner target profile is poorly resolved in these plasmas and further experiments with corroborating diagnostics are required to confirm this finding. The pressure and power loss factors defined in the two-point model [1][2][3][4] of the divertor scrape-off layer (SOL) and the sources contributing to the loss factors are calculated through post-processing of the SOLPS-ITER results. The momentum losses are mainly driven by plasma-neutral interaction and the power losses by plasma-neutral interaction and carbon radiation. The presence of carbon impurities in the simulation enhances pressure and power dissipation compared to the pure D case. Carbon radiation is a strong power loss channel which cools the plasma, but its effect on the pressure balance is indirect. Reduction of the electron temperature indirectly increases the momentum loss by decreasing the static pressure and increasing the volumetric reaction rates which are responsible for the loss of momentum. As a result, the addition of carbon saturates the momentum and power losses in the flux tube at lower upstream densities, reducing the rollover threshold of upstream density. The relative strengths of the various mechanisms contributing to momentum and power loss depends on the radial distance of the SOL flux tubes from the separatrix (near/far SOL) and the target (inner/outer target). This is related to the strong D2 molecule accumulation near the outer strike point, which makes the deuterium gas density at the outer target 2-10 times higher than that at the inner target. A large portion of the recycled neutral particles from both targets reach and accumulate in the outer SOL, which is attributed in strong part to the target inclination and gap structure between the central and outboard divertors and hence to the impact of geometry. The accumulated neutrals enhance the reactions involving D2 which cause momentum and power loss.

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Section: Setup Of Solps-iter Simulationsmentioning

confidence: 99%