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  • ELM pacing investigations at JET with the new pellet launcher
    Lang, P.T. ...
    A new pellet injection system was installed at JET designed for both fuelling and ELM pacing. The purpose of the pacing section was to validate pellet ELM pacing as a suitable tool for ELM mitigation ... in ITER. Pellet pacing was confirmed at the large size scale of JET. The dynamics of triggered ELMs was investigated with respect to their spontaneous counterparts. Triggered ELMs show features also typical for spontaneous ELMs in several operational regimes. Since none of these regimes was unsettled by the pellets this is a strong hint for compatibility with other plasma control tools. Observations and modelling results indicate the ELM triggering occurs by the evolution of the pellet ablation plasmoid into the first ELM filament followed by a poloidal spread of the instability. An ELM obviously can be forced by a pelletdue to the strong local perturbation imposed already under unusual onsetconditions but then evolves like any ELM typical for the corresponding plasma regime. For tool optimization the pellet mass and hence the convective confinement losses imposed have to be minimized. In our experiments, a lower mass threshold was observed for the first time. It has been found that to reliably trigger an ELM the pellet needs to be sufficiently large (and fast) to penetrate close to the pedestal top. Recent investigations are clear steps forward to validate the pellet pacing approach for ITER.
    Source: Nuclear fusion. - ISSN 0029-5515 (Iss. 3, Vol. 51, 2011, 033010-1-033010-12)
    Type of material - article, component part
    Publish date - 2011
    Language - english
    COBISS.SI-ID - 25303591

source: Nuclear fusion. - ISSN 0029-5515 (Iss. 3, Vol. 51, 2011, 033010-1-033010-12)
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