Progress of KSTAR 5-GHz Lower Hybrid Current Drive System

Park, S.; Bae, Y.S.; Kim, J. H.; Do, Heejin; Kim, H. T.; Kim, K. M.; Kim, H. K.; Kim, H. J.; Han, W.S.; Yang, H. L.; Kwak, J. G.; Namkung, W.; Cho, M. H.; Park, H.; Delpech, L.; Hillairet, J.; Magne, R.; Hoang, G. T.; Litaudon, X.; Wallace, G. M.; Shiraiwa, S.; Vieira, R.; Doody, J.

doi:10.13182/fst12-493

Cited by 8 publications

(1 citation statement)

References 14 publications

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“…Since the AT operation mode in KSTAR is based on H-mode with pedestal, it would be difficult to sustain such a high performance plasma due to the lower single pass absorption if the LH wave is launched at the outer midplane. Presently, the 5 GHz KSTAR LHCD system is being operated with a 500 kW CW klystron prototype, which has recently demonstrated with 1000 s pulse operation at 500 kW output power at the window, and a conventional fully active waveguide grill launcher with fixed n || ~ 2 installed at the low-field side (outer) midplane [14]. Figure 1 shows the layout of the KSTAR 5 GHz, 500 kW LHCD system.…”

Section: Introductionmentioning

confidence: 99%

Simulation study of proposed off-midplane lower hybrid current drive in KSTAR

Bae¹,

Shiraiwa²,

Bonoli³

et al. 2016

Plasma Phys. Control. Fusion

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A new proposal of lower hybrid (LH) wave launching is studied for efficient current drive aiming for high performance H-mode operation in Korea Superconducting Tokamak Advanced Research (KSTAR). This new concept is the off-midplane launch which results in a rapid up-shift of the parallel component of refractive index and hence simultaneously maintains good wave accessibility and efficient single pass absorption via Landau damping. In order to locate an optimal position of the launcher in the poloidal direction, the ray-tracing and Fokker-Planck codes were used. Based on a survey of the LH wave launch parameters and operation conditions including the compatibility issues with the existing in-vessel components, the LH wave launch from the top position near the upper X-point of the plasma separatrix provides the possibility to eliminate the accessibility problem and reduce parasitic edge loss for the KSTAR high performance H-mode operation scenario using 5 GHz lower hybrid current drive.

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Section: Introductionmentioning

confidence: 99%

Simulation study of proposed off-midplane lower hybrid current drive in KSTAR

Bae¹,

Shiraiwa²,

Bonoli³

et al. 2016

Plasma Phys. Control. Fusion

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Design and tests of 500 kW RF windows for the ITER LHCD system

Hillairet

Kim

Faure³

et al. 2015

Fusion Engineering and Design

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In the frame of a R&D effort conducted by CEA toward the design and the qualification of a 5 GHz LHCD system for the ITER tokamak, two 5 GHz 500 kW/5 s windows have been designed, manufactured and tested at high power in collaboration with the National Fusion Research Institute (NFRI). The window design rely on a symmetrical pill-box concept with a cylindrical beryllium oxide ceramic brazed on an actively water cooled copper skirt. The ceramic RF properties have been measured on a test sample to get realistic values for guiding the design. Low power measurements of the manufactured windows show return losses below -32 dB and insertion losses between -0.01 dB and -0.05 dB, with an optimum frequency shifted toward lower frequencies. High power tests conducted at NFRI show unexpected total power loss for both windows. The ceramic temperature during RF pulses has been found to reach unexpected high temperature, preventing these windows to be used under CW conditions. A post-mortem RF analysis of samples taken from one window shows that the dielectric properties of the ceramic were not the ones measured on the manufacturer sample, which partly explain the differences with the reference modelling.

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