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Title: Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas

Journal Article · · Physics of Plasmas
DOI:https://doi.org/10.1063/1.4981209· OSTI ID:1375656

The dynamics of RE (runaway electrons) in fusion plasmas span a wide range of temporal scales, from the fast gyro-motion, ~10–11 s, to the observational time scales, ~10–2 → 1 s. To cope with this scale separation, RE are usually studied within the bounce-average 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 three-dimensional 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 Landau-Lifshitz formulation of the Abraham-Lorentz-Dirac 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 gyro-averaging in the relativistic regime. To explore the practical impact of the results, DIII-D and ITER-like parameters are used in the simulations.

Research Organization:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1375656
Alternate ID(s):
OSTI ID: 1420618; OSTI ID: 1465072
Journal Information:
Physics of Plasmas, Journal Name: Physics of Plasmas Vol. 24 Journal Issue: 4; ISSN 1070-664X
Publisher:
American Institute of PhysicsCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 24 works
Citation information provided by
Web of Science

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Cited By (9)

Physics of runaway electrons in tokamaks journal June 2019
Conservative magnetic moment of runaway electrons and collisionless pitch-angle scattering journal August 2018
Test particles dynamics in the JOREK 3D non-linear MHD code and application to electron transport in a disruption simulation journal December 2017
MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D journal October 2019
Numerical simulation of runaway electrons: 3-D effects on synchrotron radiation and impurity-based runaway current dissipation journal May 2018
On the synchrotron emission in kinetic simulations of runaway electrons in magnetic confinement fusion plasmas journal October 2017
Interpretation of runaway electron synchrotron and bremsstrahlung images journal June 2018
Runaway electron modelling in the self-consistent core European Transport Simulator journal June 2019
Resolving runaway electron distributions in space, time, and energy journal May 2018