Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas
Abstract
The dynamics of RE (runaway electrons) in fusion plasmas span a wide range of temporal scales, from the fast gyromotion, ~10^{–11} s, to the observational time scales, ~10^{–2} → 1 s. To cope with this scale separation, RE are usually studied within the bounceaverage or the guiding center approximations. Although these approximations have yielded valuable insights, a study with predictive capabilities of RE in fusion plasmas calls for the incorporation of full orbit effects in configuration space in the presence of threedimensional magnetic fields. We present numerical results on this problem using the Kinetic Orbit Runaway electrons Code that follows relativistic electrons in general electric and magnetic fields under the full Lorentz force, collisions, and radiation losses. At relativistic energies, the main energy loss is due to radiation damping, which we incorporate using the LandauLifshitz formulation of the AbrahamLorentzDirac force. The main focus is on full orbit effects on synchrotron radiation. It is shown that even in the absence of magnetic field stochasticty, neglecting orbit dynamics can introduce significant errors in the computation of the total radiated power and the synchrotron spectra. The statistics of collisionless (i.e., full orbit induced) pitch angle dispersion, and its key role played on synchrotronmore »
 Authors:

 Oak Ridge National Laboratory, Oak Ridge, Tennessee 378318071, USA
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1375656
 Alternate Identifier(s):
 OSTI ID: 1420618; OSTI ID: 1465072
 Grant/Contract Number:
 AC0500OR22725
 Resource Type:
 Published Article
 Journal Name:
 Physics of Plasmas
 Additional Journal Information:
 Journal Name: Physics of Plasmas Journal Volume: 24 Journal Issue: 4; Journal ID: ISSN 1070664X
 Publisher:
 American Institute of Physics
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY
Citation Formats
Carbajal, L., delCastilloNegrete, D., Spong, D., Seal, S., and Baylor, L. Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas. United States: N. p., 2017.
Web. doi:10.1063/1.4981209.
Carbajal, L., delCastilloNegrete, D., Spong, D., Seal, S., & Baylor, L. Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas. United States. doi:10.1063/1.4981209.
Carbajal, L., delCastilloNegrete, D., Spong, D., Seal, S., and Baylor, L. Tue .
"Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas". United States. doi:10.1063/1.4981209.
@article{osti_1375656,
title = {Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas},
author = {Carbajal, L. and delCastilloNegrete, D. and Spong, D. and Seal, S. and Baylor, L.},
abstractNote = {The dynamics of RE (runaway electrons) in fusion plasmas span a wide range of temporal scales, from the fast gyromotion, ~10–11 s, to the observational time scales, ~10–2 → 1 s. To cope with this scale separation, RE are usually studied within the bounceaverage or the guiding center approximations. Although these approximations have yielded valuable insights, a study with predictive capabilities of RE in fusion plasmas calls for the incorporation of full orbit effects in configuration space in the presence of threedimensional magnetic fields. We present numerical results on this problem using the Kinetic Orbit Runaway electrons Code that follows relativistic electrons in general electric and magnetic fields under the full Lorentz force, collisions, and radiation losses. At relativistic energies, the main energy loss is due to radiation damping, which we incorporate using the LandauLifshitz formulation of the AbrahamLorentzDirac force. The main focus is on full orbit effects on synchrotron radiation. It is shown that even in the absence of magnetic field stochasticty, neglecting orbit dynamics can introduce significant errors in the computation of the total radiated power and the synchrotron spectra. The statistics of collisionless (i.e., full orbit induced) pitch angle dispersion, and its key role played on synchrotron radiation, are studied in detail. Numerical results are also presented on the pitch angle dependence of the spatial confinement of RE and on full orbit effects on the competition of electric field acceleration and radiation damping. Lastly, full orbit calculations are used to explore the limitations of gyroaveraging in the relativistic regime. To explore the practical impact of the results, DIIID and ITERlike parameters are used in the simulations.},
doi = {10.1063/1.4981209},
journal = {Physics of Plasmas},
number = 4,
volume = 24,
place = {United States},
year = {2017},
month = {4}
}
DOI: 10.1063/1.4981209
Web of Science
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