On the measurement of the threshold electric field for runaway electron generation in the Frascati Tokamak Upgrade

Z. Popovic, B. Esposito, J.R. Mart�n-Sol�s, W. Bin, P. Buratti, D. Carnevale, F. Causa, M. Gospodarczyk, D. Marocco, G. Ramogida, M. Riva

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Abstract

Experiments have been carried out to evaluate the threshold electric field for runaway generation during the flat-top phase of ohmic discharges in the Frascati Tokamak Upgrade tokamak. An investigation of the conditions for runaway electron generation and suppression has been performed for a wide range of plasma parameter values. The measured threshold electric field is found to be significantly larger (∼2-5 times) than predicted by the relativistic collissional theory of runaway generation, ER=ne e3 lnΛ/4π ϵ02 me c2, and can be explained to a great extent by an increase of the critical electric field due to the effect of the electron synchrotron radiation losses. These findings are consistent with the results of an ITPA joint experiment to study the onset, growth, and decay of relativistic runaway electrons [Granetz et al., Phys. Plasmas 21, 072506 (2014)]. Confirmation of these results for disruptions with high electric field might imply significantly lower requirements on electron densities for suppression and prevention of runaway formation in ITER.
Original languageEnglish
Article number122501
Pages (from-to)-
JournalPhysics of Plasmas
Volume23
Issue number12
DOIs
Publication statusPublished - 1 Dec 2016
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics

Cite this

Popovic, Z., Esposito, B., Mart�n-Sol�s, J. R., Bin, W., Buratti, P., Carnevale, D., ... Riva, M. (2016). On the measurement of the threshold electric field for runaway electron generation in the Frascati Tokamak Upgrade. Physics of Plasmas, 23(12), -. [122501]. https://doi.org/10.1063/1.4968839