Experimental Observation of Increased Threshold Electric Field for Runaway Generation Due to Synchrotron Radiation Losses in the FTU Tokamak Articles uri icon

publication date

  • October 2010

start page

  • 185002

issue

  • 18

volume

  • 105

international standard serial number (ISSN)

  • 0031-9007

electronic international standard serial number (EISSN)

  • 1079-7114

abstract

  • The threshold electric field for runaway generation has been investigated during runaway suppression experiments by means of electron-cyclotron-resonance heating in the flattop phase of FTU
    discharges. Runaway suppression has been experimentally found to occur
    at electric fields substantially larger than those predicted by the
    relativistic collisional theory of runaway generation,
    ER=nee3lnLambda/4piepsilon0(2)mec2. These experimental results are consistent with
    an increase of the critical electric field due to the electron
    synchrotron radiation losses. No runaway electrons are found in FTU
    experiments below the radiation threshold. These results support
    evidence for a new threshold electric field for runaway generation that
    accounts for the effect of the synchrotron losses, and which should be
    considered when making predictions on runaway generation and mitigation
    in devices such as ITER.