ELMs and strike point movements
2008 (English)In: Nuclear Fusion, ISSN 0029-5515, E-ISSN 1741-4326, Vol. 48, no 6Article in journal (Refereed) Published
A detailed study of position changes of plasma strike points before and after edge localized modes (ELMs) in JET was carried out. A hypothesis being tested is that in an ELM previously closed edge field lines would open up, releasing plasma current and leading to the formation of a new, smaller separatrix. It was observed that after each ELM strike points have shifted a few centimetres towards the plasma centre ( up in JET). In some cases a transient (< 100 mu s), upwards large (> 10 cm) jump of strike positions was observed first. It was followed by an equally fast jump down to the shifted strike positions. Such behaviour has not been described in previous computational models of the ELM. Therefore two novel instability mechanisms are presented, which contribute to explain the changes in strike point position: an X-point instability, due to positive toroidal current density at the X-point, and a diamagnetic instability, due to negative inboard toroidal current density.
Place, publisher, year, edition, pages
2008. Vol. 48, no 6
edge localized modes, magnetohydrodynamic stability, transport barrier, mhd activity, i elms, jet, tokamaks, divertor, plasmas, instabilities
IdentifiersURN: urn:nbn:se:kth:diva-17664DOI: 10.1088/0029-5515/48/6/065005ISI: 000257324500006ScopusID: 2-s2.0-44949094371OAI: oai:DiVA.org:kth-17664DiVA: diva2:335709
QC 201005252010-08-052010-08-05Bibliographically approved