Conceptual design of the KSTAR Motor Generator

Kim, Chang-Hwan; Kong, Jong-Dae; Eom, Dae-Young; Joung, Nam-Young; Lee, Woojin; Kim, Yang-Soo; Kwon, M.; Han, Chul-Woo; Lee, Sel-Ki; Parker, F.J.; Hopkinson, D. A.; Flem, G.D. Le

doi:10.1016/j.fusengdes.2012.04.020

Cited by 8 publications

(1 citation statement)

References 4 publications

(5 reference statements)

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“…The (Nb 3 Sn) conductors of PF1-PF5 are designed and manufactured with a maximum current of 25 kA/turn, but the operating current of the central solenoid composed of PF1-PF4 is currently limited to 15 kA/turn. This is relevant for the safe operation of the preload uncertainty of the central solenoid [13] and the apparent power limited to 140 MVA supplied by the KSTAR motor generator [14,15]. The available poloidal flux is approximately estimated from the initial magnetization to the maximum PF coil current of 15 kA/turn.…”

Section: Approaches For the Lower Loop Voltage Scenariomentioning

confidence: 99%

Development of high-performance long-pulse discharge in KSTAR

Kim,

Jeon,

Han

et al. 2023

Nucl. Fusion

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High-performance long-pulse plasma operation is essential for producing economically viable fusion energy in tokamak devices. To achieve such discharges in KSTAR, firstly, the rapid increase in the temperature of plasma-facing components was mitigated. The temperature increase of the poloidal limiter, especially, was associated with beam-driven fast ion orbit loss and the discrepancy of the equilibrium reconstructed with heated magnetic probes of signal drift. The fast ions lost to the poloidal limiter were reduced by optimizing the plasma shape and the composition of neutral beam injection (NBI). This nonlinear signal drift was successfully reduced by a new thermal shielding protector on the magnetic probes. Secondly, a lower loop voltage approach was implemented to reduce a poloidal flux consumption rate. A plasma current of 400 kA and a line-averaged electron density of ∼2.0 × 1019 m−3 were chosen by considering the L–H power threshold, fast ion orbit loss, and beam shine-through power loss for low loop voltage in KSTAR. In addition, the application of electron cyclotron heating also helped maintain the plasma with low loop voltage (∼25 mV) by enhancing the NBI-driven current and achieving a high poloidal beta (β P) state. KSTAR has achieved a long pulse (∼90 s) operation with the high performance of β P ⩽ 2.7, thermal energy confinement enhancement factor (H98y2) ∼ 1.1, and fraction of non-inductive current (f NI) ⩽ 0.96. Still, gradual degradation of the plasma performance has been observed over time in the discharges. In one of the long-pulse discharges, β P reduced by ∼18% over the time of ∼8τ R (current relaxation time, τ R ∼ 5 s) and ∼1067τ E,th (thermal energy confinement time, τ E,th ∼ 45 ms). The degradation may be closely associated with weak, yet growing, and persistent toroidal Alfvén eigenmodes and their effect on fast ion confinement.

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Section: Approaches For the Lower Loop Voltage Scenariomentioning

confidence: 99%

Development of high-performance long-pulse discharge in KSTAR

Kim,

Jeon,

Han

et al. 2023

Nucl. Fusion

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Design of the Double-Fed Unit for J-TEXT 100 MVA Pulse Generator System

et al. 2015

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J-TEXT, formerly known as TEXT-U, has been reconstructed since 2004. The 100 MVA pulse generator system is the main power supply of J-TEXT, including the toroidal coil, the ohmic heat coil and the divertor coil and high-voltage power supply for Electron Cyclotron Resonance Heating. The pulse generator system was designed in USA with a 60 Hz grid so that the maximum rotation speed of the flywheel was 713 rpm and the maximum stored energy was 185 MJ. Now in China the grid is 50 Hz, in asynchronous mode the maximum rotation speed of the flywheel is 598 rpm and maximum stored energy is 128 MJ. To reach the designed maximum rotation speed of the pulse generator system, a doubled-fed unit is designed to ensure the tokamak operates with high parameters. This paper presents the design procedure of the double-fed unit: including the stator field oriented control of the double-fed induction motor, voltage oriented control of the AC-DC rectifier and the structure of the control system. The experiment results show the feasibility of the unit.

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