Effect of a resistive vacuum vessel on dynamo mode rotation in reversed field pinches

R. Fitzpatrick, S.C. Guo, D.J. Den Hartog, C.C. Hegna

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Locked (i.e., nonrotating) dynamo modes give rise to a serious edge loading problem during the operation of high current reversed field pinches. Rotating dynamo modes generally have a far more benign effect. A simple analytic model is developed in order to investigate the slowing down effect of electromagnetic torques due to eddy currents excited in the vacuum vessel on the rotation of dynamo modes in both the Madison Symmetric Torus (MST) [Fusion Technol. 19, 131 (1991)] and the Reversed Field Experiment (RFX) [Fusion Eng. Des. 25, 335 (1995)]. This model strongly suggests that vacuum vessel eddy currents are the primary cause of the observed lack of mode rotation in RFX. The eddy currents in MST are found to be too weak to cause a similar problem. The crucial difference between RFX and MST is the presence of a thin, highly resistive vacuum vessel in the former device. The MST vacuum vessel is thick and highly conducting. Various locked mode alleviation methods are discussed. © 1999 American Institute of Physics.
Original languageEnglish
Pages (from-to)3878 - 3889
Number of pages12
JournalPhysics of Plasmas
Issue number10
Publication statusPublished - 1999
Externally publishedYes


All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Fitzpatrick, R., Guo, S. C., Den Hartog, D. J., & Hegna, C. C. (1999). Effect of a resistive vacuum vessel on dynamo mode rotation in reversed field pinches. Physics of Plasmas, 6(10), 3878 - 3889. https://doi.org/10.1063/1.873650