ELM control experiments in the KSTAR device

Kim, Jaewook; Jeon, Y.M.; Xiao, W.W.; Yoon, S.W.; Park, J.-K.; Yun, G. S.; Ahn, J.-W.; Kim, H.S.; Yang, H. L.; Kim, H.K.; Park, S.; Jeong, J.H.; Jung, Mi Jun; Choe, G.H.; Ko, W. H.; Lee, S.-G.; Nam, Y. U.; Bak, J.G.; Lee, K.D.; Na, H.K.; Hahn, S.H.; Diamond, P. H.; Rhee, T.; Kwon, Jae Min; Sabbagh, S. A.; Park, Y. S.; Park, H.K.; Na, Y.S.; Kim, W.C.; Kwak, J.G.

doi:10.1088/0029-5515/52/11/114011

Cited by 46 publications

(36 citation statements)

References 42 publications

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“…In the KSTAR tokamak, H-mode discharges with NBI and ECRH for diverted plasmas (R-1.8 m, a-0.5 m, κ = 1.8-2.0, BT = 1.6-2.4 T, Ip = 0.6-0.7 MA, <ne> = (1.2-4.3)×10 19 m −3 ) are achieved successfully [19]. The successful experiments of SMBI fuelling and ELM mitigation have been performed in 2011 [20]. The SMBI system was newly installed at a median port of the vacuum vessel to explore ELM mitigation.…”

Section: History Of Smbi and Its Application In Hl-2a And Kstarmentioning

confidence: 99%

ELM mitigation by supersonic molecular beam injection: KSTAR and HL-2A experiments and theory

et al. 2014

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We report recent experimental results from HL-2A and KSTAR on ELM mitigation by supersonic molecular beam injection (SMBI). Cold particle deposition within the pedestal by SMBI is verified in both machines.The signatures of ELM mitigation by SMBI are an ELM frequency increase and ELM amplitude decrease.These persist for an SMBI influence time τI. Here, τI is the time for the SMBI influenced pedestal profile to refill. An increase in f SMBI ELM /f 0 ELM and a decrease in the energy loss per ELM WELM were achieved in both machines. Physical insight was gleaned from studies of density and vφ(toroidal rotation velocity) evolution, particle flux and turbulence spectra, divertor heat load. The characteristic gradients of the pedestal density soften and a change in vφwas observed during a τI time. The spectra of the edge particle flux Г~ < ˜vr˜ne> and density fluctuation with and without SMBI were measured in HL-2A and in KSTAR, respectively. A clear phenomenon observed is the decrease in divertor heat load during the τI time in HL-2A. Similar results are the profiles of saturation current density Jsat with and without SMBI in KSTAR. We note that τI/τp (particle confinement time) is close to ~1, although there is a large difference in individual τI between the two machines. This suggests that τI is strongly related to particle-transport events. Experiments and analysis of a simple phenomenological model support the important conclusion that ELM mitigation by SMBI results from an increase in higher frequency fluctuations and transport events in the pedestal.

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Section: History Of Smbi and Its Application In Hl-2a And Kstarmentioning

confidence: 99%

ELM mitigation by supersonic molecular beam injection: KSTAR and HL-2A experiments and theory

et al. 2014

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“…This technique was first demonstrated on the Tokamak à configuration variable (TCV) tokamak 65 ; it was later demonstrated on ASDEX Upgrade 66 . It has also been demonstrated on JET 67 , the National Spherical Torus Experiment (NSTX) 68 and the KSTAR device 69 . The technique has become routine on JET but it may not be appropriate for use on the high-performance shots on ITER because of the demands on the vertical control system 64 .…”

Section: Box 2 | Ballooning Modes and Kink Modesmentioning

confidence: 98%

Filamentary plasma eruptions and their control on the route to fusion energy

et al. 2020

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“…. The approach, originally pioneered on TCV [35] has been also applied successfully on other devices [36][37][38]. Several simulations indicate that it could be considered a backup system also in ITER [6].…”

Section: Elm Pacing Via Vertical Kicks and With Pelletsmentioning

confidence: 99%

A methodology for discriminating phase and amplitude effects on synchronization in tokamak pacing experiments

Murari¹,

Peluso²,

Lang³

et al. 2022

Front. Phys.

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The control of macroscopic instabilities, such as Edge Localised Modes (ELMs) and sawteeth, is becoming an essential ingredient in the optimisation of scenarios in preparation for the next generation of tokamaks and the demonstrative reactor. Various pacing experiments have been indeed successfully carried out in many devices but various details of their interactions with the plasma remain poorly understood, in particular the assessment of the relative contribution of driver phase and amplitude to frequency synchronization. In this paper, a data analysis methodology for investigating the details of pacing experiments is proposed. The approach is based on the wavelet decomposition of the signals and the following implementation of information theoretic indicators, to determine the basic form of the interactions. The main analysis tool deployed is the conditional mutual information, equivalent to the informational transfer entropy, which can detect actual causal influences and not only statistical correlations between signals. The most flexible type of ELM pacing, the vertical kicks, permits to clearly confirm the potential of the analysis tools developed. In the dedicated experiments to optimise the ELMs pacing with pellets and sawteeth synchronization with ICRH modulation, the main effect is due to the influence of the amplitude of the external perturbations. Some evidence of phase synchronization has been found, in both JET and AUG, which indicates the direction of possible future optimization of the interventions. Indeed, adjusting the phase of the pacing schemes would free density and ICRH power to give more leeway to other feedback loops, an important aspect, particularly for the integrated control of the next generation of devices. The long-term objective of this line of research is therefore twofold. On the one hand, it is expected to contribute to better physical interpretation of the pacing experiments and possibly also of their target instabilities. From an operational perspective, hopefully these insights will help in the development of reactor relevant scenarios, as exemplified by examples of ELM a pacing with pellets carried out in preparation for the DT campaign on JET.

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ELM control experiments in the KSTAR device

Cited by 46 publications

References 42 publications

ELM mitigation by supersonic molecular beam injection: KSTAR and HL-2A experiments and theory

ELM mitigation by supersonic molecular beam injection: KSTAR and HL-2A experiments and theory

Filamentary plasma eruptions and their control on the route to fusion energy

A methodology for discriminating phase and amplitude effects on synchronization in tokamak pacing experiments

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