Stability of Superconducting Magnet for KSTAR

Park, S.H.; Chung, Woosuk; Lee, H.J.; Han, W.S.; Moon, K.M.; Park, W.W.; Kim, J.S.; Yonekawa, H.; Chu, Yong; Cho, K.W.; Park, K.R.; Kim, W.C.; Kim, Y.S.; Oh, Y.K.; Bak, J.S.

doi:10.1109/tasc.2008.920828

Cited by 8 publications

(2 citation statements)

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“…These phenomena have a substantial influence on the helium behavior in the CICC. The measured helium properties showed quite different results from the estimated helium behavior analysed by several simulations in the ideal condition [3]- [5]. During the second campaign, the flow reduction phenomenon in the HDS became more serious, and went out of measurement range in several operations, which means that the helium flow was entirely blocked or changed to the reversed direction.…”

Section: Introductionmentioning

confidence: 75%

Analysis of the Reversal Flow Phenomenon of Supercritical Helium Due to AC Losses in the KSTAR PF Magnets at the Low Current

Lee

Park²,

Chu³

et al. 2011

IEEE Trans. Appl. Supercond.

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Superconducting magnets of the Korea Superconducting Tokamak Advanced Research (KSTAR) are cooled by supercritical helium with 4.5 K, which was supplied and recovered by the 9 kW of the Helium Refrigerator System (HRS). While current is being charged, the supercritical helium expands to both side of the helium inlet and the outlet of the magnets due to the generated AC losses. To maintain the pressure gradient, both the supply and the return pressures of the HRS are increased at the same time and the differential pressure of the HRS was reduced after the event. However, the pressure rising in the magnets may block the helium flow or create reversal flow of the helium. During unipolar experiment of PF1 magnet up to 2 kA with 1 kA/s of ramp-up rate, the mass flow rate was decreased at the PF1 cooling tube (manifold) in the helium distribution system (HDS), whereas the pressure is increased and the temperature is to be increased or decreased according to compression and expansion of the heated helium in the magnets. For the bipolar experiment of PF1 up to 2 kA with 1 kA/s ramp-up rate and 2 kA/s ramp-down rate, the conditions in the helium flow were drastically changed, especially the mass flow rate was measured to be maintained at zero for a few second (more than 4 s). This behavior could decisively affect the cryogenic stabilities in the magnet, and may impose a major limit on the long pulse operation of KSTAR. In this paper, we investigated this behavior and analysed by using 1-dimentional thermo-hydraulic code, GANDALF.Index Terms-CICC, KSTAR, reversal flow, thermo-hydraulic phenomenon of supercritical helium.

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Section: Introductionmentioning

confidence: 75%

Analysis of the Reversal Flow Phenomenon of Supercritical Helium Due to AC Losses in the KSTAR PF Magnets at the Low Current

Lee

Park²,

Chu³

et al. 2011

IEEE Trans. Appl. Supercond.

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“…8). We present result of CSMC current charging test [5] and then compare to KSTAR TF commissioning result later. CSMC was charged up to 20 kA and then kept for 8 hours (Fig.…”

Section: Friction Factormentioning

confidence: 99%

Hydraulics of KSTAR Central Solenoid Model Coil 2nd Campaign

Park

Han

Moon

et al. 2009

IEEE Trans. Appl. Supercond.

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KSTAR (Korea Superconducting Tokamak Advanced Research) superconducting magnet consists of a CICC (Cable-InConduit Conductor) and is cooled down less than 5 K using supercritical helium. The length of CICC is 610 m for TF coil and maximum about 2,500 m for PF coil respectively, especially the cooling channel is about maximum 300 m in PF coil because of continuous winding scheme.There are many cooling channels in KSTAR coils especially 84 channels in TF magnet system and 100 channels in PF magnet system. Flow imbalance affects cool down of magnet and leads to a difficulty of flow control.The pressure drop between CICC terminals has a close relationship with CICC hydraulic characteristic, helium refrigerator's performance and efficiency. The friction factor which is a representative parameter can be obtained under cryogenic operation condition. We attempt to find out the friction factor of KSTAR CS and PF CICC according to the test result of KSTAR CSMC (Central Solenoid Model Coil) 2nd campaign and compare the results with previous tests.The hydraulic characteristics of KSTAR superconducting magnet system like mass flow distribution, friction factor in conductor, pressure drop and etc during CSMC test and initial commissioning of KSTAR are presented.We can confirm the KSTAR CICC's unique hydraulic behavior in states of cool down and current charging period. Also, we expect that measured data will help to operate KSTAR and be a reference for thermo-hydraulic simulation.

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