skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Spatiotemporal Evolution of Runaway Electron Momentum Distributions in Tokamaks

Journal Article · · Physical Review Letters
 [1];  [2];  [3];  [1];  [1];  [4];  [5];  [6];  [4];  [2];  [6];  [7]
  1. General Atomics, San Diego, CA (United States)
  2. Oak Ridge Associated Univ., Oak Ridge, TN (United States)
  3. Max-Planck Inst. for Plasma Physics, Greifswald (Germany)
  4. Princeton Univ., NJ (United States)
  5. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
  6. Univ. of California, San Diego, CA (United States)
  7. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

Novel spatial, temporal, and energetically resolved measurements of bremsstrahlung hard-x-ray (HXR) emission from runaway electron (RE) populations in tokamaks reveal nonmonotonic RE distribution functions whose properties depend on the interplay of electric field acceleration with collisional and synchrotron damping. Measurements are consistent with theoretical predictions of momentum-space attractors that accumulate runaway electrons. RE distribution functions are measured to shift to a higher energy when the synchrotron force is reduced by decreasing the toroidal magnetic field strength. Increasing the collisional damping by increasing the electron density (at a fixed magnetic and electric field) reduces the energy of the nonmonotonic feature and reduces the HXR growth rate at all energies. Higher-energy HXR growth rates extrapolate to zero at the expected threshold electric field for RE sustainment, while low-energy REs are anomalously lost. The compilation ofHXR emission from different sight lines into the plasma yields energy and pitch-angle-resolved RE distributions and demonstrates increasing pitch-angle and radial gradients with energy.

Research Organization:
General Atomics, San Diego, CA (United States); Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)
Sponsoring Organization:
USDOE
Grant/Contract Number:
FC02-04ER54698; FG02-07ER54917; AC05-00OR22725; FC02-99ER54512; SC0016268
OSTI ID:
1374548
Alternate ID(s):
OSTI ID: 1365606
Journal Information:
Physical Review Letters, Vol. 118, Issue 25; ISSN 0031-9007
Publisher:
American Physical Society (APS)Copyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 52 works
Citation information provided by
Web of Science

References (30)

Radiation reaction induced non-monotonic features in runaway electron distributions journal July 2015
Simulation of runaway electrons during tokamak disruptions journal August 2003
Visible imaging and spectroscopy of disruption runaway electrons in DIII-D journal April 2013
An ITPA joint experiment to study runaway electron generation and suppression journal July 2014
Effective Critical Electric Field for Runaway-Electron Generation journal March 2015
Numerical characterization of bump formation in the runaway electron tail journal January 2016
Adjoint Fokker-Planck equation and runaway electron dynamics journal January 2016
Growth and decay of runaway electrons above the critical electric field under quiescent conditions journal February 2014
Suppression of runaway electron avalanches by radial diffusion journal January 2000
Relativistic limitations on runaway electrons journal June 1975
Avalanche runaway growth rate from a momentum-space orbit analysis journal June 1999
Status of research toward the ITER disruption mitigation system journal November 2014
Momentum–space structure of relativistic runaway electrons journal June 1998
Tomography of the fast electron bremsstrahlung emission during lower hybrid current drive on TORE SUPRA journal October 1999
Applying the new gamma ray imager diagnostic to measurements of runaway electron Bremsstrahlung radiation in the DIII-D Tokamak (invited) journal August 2016
Runaway electron drift orbits in magnetostatic perturbed fields journal March 2011
High performance gamma-ray spectrometer for runaway electron studies on the FT-2 tokamak
  • Shevelev, A. E.; Khilkevitch, E. M.; Lashkul, S. I.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 830 https://doi.org/10.1016/j.nima.2016.05.075
journal September 2016
Damping of relativistic electron beams by synchrotron radiation journal December 2001
Measurement of runaway electron energy distribution function during high-Z gas injection into runaway electron plateaus in DIII-Da) journal May 2015
Theory of runaway electrons in ITER: Equations, important parameters, and implications for mitigation journal March 2015
Effect of applied toroidal electric field on the growth/decay of plateau-phase runaway electron currents in DIII-D journal September 2011
Disruptions in ITER and strategies for their control and mitigation journal August 2015
Theory for avalanche of runaway electrons in tokamaks journal October 1997
Experimental Observation of Increased Threshold Electric Field for Runaway Generation due to Synchrotron Radiation Losses in the FTU Tokamak journal October 2010
Theory of Two Threshold Fields for Relativistic Runaway Electrons journal April 2015
Adjoint method and runaway electron avalanche journal December 2016
Space dependent, full orbit effects on runaway electron dynamics in tokamak plasmas journal April 2017
Reconstruction of distribution functions of fast ions and runaway electrons in fusion plasmas using gamma-ray spectrometry with applications to ITER journal November 2013
Chapter 3: MHD stability, operational limits and disruptions journal June 2007
Gamma ray imager on the DIII-D tokamak journal April 2016

Cited By (23)

Dynamics of positrons during relativistic electron runaway journal October 2018
Numerical simulation of runaway electrons: 3-D effects on synchrotron radiation and impurity-based runaway current dissipation journal May 2018
Resolving runaway electron distributions in space, time, and energy journal May 2018
High resolution gamma-ray spectrometer with MHz capabilities for runaway electron studies at ASDEX Upgrade journal October 2018
Development of a new compact gamma-ray spectrometer optimised for runaway electron measurements journal October 2018
Conversion of magnetic energy to runaway kinetic energy during the termination of runaway current on the J-TEXT tokamak journal March 2018
Study of runaway electrons in TUMAN-3M tokamak plasmas journal May 2018
Runaway electron experiments at COMPASS in support of the EUROfusion ITER physics research journal November 2018
Low-frequency whistler waves in quiescent runaway electron plasmas journal November 2018
Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod journal October 2018
The role of kinetic instabilities in formation of the runaway electron current after argon injection in DIII-D journal November 2018
Kink instabilities of the post-disruption runaway electron beam at low safety factor journal March 2019
Modeling of bremsstrahlung emission from the confined runaway electrons and applications to the hard x-ray monitor of ITER journal October 2018
Interpretation of runaway electron synchrotron and bremsstrahlung images journal June 2018
Measurements of runaway electron synchrotron spectra at high magnetic fields in Alcator C-Mod journal June 2018
Conservative magnetic moment of runaway electrons and collisionless pitch-angle scattering journal August 2018
Observation of toroidal Alfvén eigenmode excited by energetic electrons induced by static magnetic perturbations in the EAST tokamak journal August 2018
DIII-D research towards establishing the scientific basis for future fusion reactors journal June 2019
Physics of runaway electrons in tokamaks journal June 2019
MARS-F modeling of post-disruption runaway beam loss by magnetohydrodynamic instabilities in DIII-D journal October 2019
Observation of rapid frequency chirping instabilities driven by runaway electrons in a tokamak journal September 2019
Interpretation of runaway electron synchrotron and bremsstrahlung images text January 2017
Spatiotemporal evolution of runaway electrons from synchrotron images in Alcator C-Mod text January 2018

Similar Records

Resolving runaway electron distributions in space, time, and energy
Journal Article · Tue May 01 00:00:00 EDT 2018 · Physics of Plasmas · OSTI ID:1374548

Recent DIII-D advances in runaway electron measurement and model validation
Journal Article · Wed May 08 00:00:00 EDT 2019 · Nuclear Fusion · OSTI ID:1374548

Spatially dependent modeling and simulation of runaway electron mitigation in DIII-D
Journal Article · Wed Nov 18 00:00:00 EST 2020 · Physics of Plasmas · OSTI ID:1374548