Bright spots generated by lower hybrid waves on JET

Karin M. Rantamäki, V. Petržílka, P. Andrew, I. Coffey, A. Ekedahl, K. Erents, V. Fuchs, M. Goniche, G. Granucci, E. Joffrin, Seppo Karttunen, P. Lomas, J. Mailloux, M. Mantsinen, M-L. Mayoral, D.C. McDonald, J.-M. Noterdaeme, V. Parail, A.A. Tuccillo, F. ŽáčekJET-EFDA contributors

Research output: Contribution to journalArticleScientificpeer-review

23 Citations (Scopus)


Observations of bright spots on the JET divertor aprons during lower hybrid current drive experiments are described. These bright spots are important because they can potentially cause damage to large tokamaks. The bright spots arise due to the impact of a fast particle beam. This beam originates from the front of the lower hybrid launcher, where thermal particles are accelerated according to theory by interaction with the high spatial harmonics of the lower hybrid wave. The bright spots are clearly related to the lower hybrid power as they disappear when the lower hybrid power is switched off. According to the analysis versus various parameters, the brightness of the spots clearly decreases with increasing plasma–wall distance, i.e. the distance between the last closed flux surface and the poloidal limiter. This is clearly beneficial for ITER, as it is designed to operate at a large plasma–wall distance.
Original languageEnglish
Pages (from-to)1101-1108
JournalPlasma Physics and Controlled Fusion
Issue number7
Publication statusPublished - 2005
MoE publication typeA1 Journal article-refereed


  • JET
  • plasma
  • fusion energy
  • fusion reactors
  • tokamak
  • ITER
  • lower hybrid current drive
  • divertor
  • divertor tiles
  • first wall
  • plasma-wall interactions


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