Resolving runaway electron distributions in space, time, and energy

C. Paz-Soldan; C. M. Cooper; P. Aleynikov; N. W. Eidietis; A. Lvovskiy; D. C. Pace; D. P. Brennan; E. M. Hollmann; C. Liu; R. A. Moyer; D. Shiraki

doi:10.1063/1.5024223

Resolving runaway electron distributions in space, time, and energy

C. Paz-Soldan, C. M. Cooper, P. Aleynikov, N. W. Eidietis, A. Lvovskiy, D. C. Pace, D. P. Brennan, E. M. Hollmann, C. Liu, R. A. Moyer, D. Shiraki

Fusion Engineering

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41 Scopus citations

Abstract

Areas of agreement and disagreement with present-day models of runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from runaway electrons (REs) with a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent RE transport, and can be used to perform full two-dimensional (energy and pitch-angle) inversions of the RE phase-space distribution. Energy-resolved measurements find qualitative agreement with modeling on the role of collisional and synchrotron damping in modifying the RE distribution shape. Measurements are consistent with predictions of phase-space attractors that accumulate REs, with non-monotonic features observed in the distribution. Temporally resolved measurements find qualitative agreement with modeling on the impact of collisional and synchrotron damping in varying the RE growth and decay rate. Anomalous RE loss is observed and found to be largest at low energy. Possible roles for kinetic instability or spatial transport to resolve these anomalies are discussed.

Original language	English
Article number	056105
Journal	Physics of Plasmas
Volume	25
Issue number	5
DOIs	https://doi.org/10.1063/1.5024223
State	Published - May 1 2018

Funding

This material was based upon the work supported in part by the U.S. Department of Energy under Grant Nos. DE-FC02-04ER54698, DE-FG02-07ER54917, DE-AC05-00OR22725, DE-FC02-99ER54512, and DE-SC0016268.

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title = "Resolving runaway electron distributions in space, time, and energy",

abstract = "Areas of agreement and disagreement with present-day models of runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from runaway electrons (REs) with a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent RE transport, and can be used to perform full two-dimensional (energy and pitch-angle) inversions of the RE phase-space distribution. Energy-resolved measurements find qualitative agreement with modeling on the role of collisional and synchrotron damping in modifying the RE distribution shape. Measurements are consistent with predictions of phase-space attractors that accumulate REs, with non-monotonic features observed in the distribution. Temporally resolved measurements find qualitative agreement with modeling on the impact of collisional and synchrotron damping in varying the RE growth and decay rate. Anomalous RE loss is observed and found to be largest at low energy. Possible roles for kinetic instability or spatial transport to resolve these anomalies are discussed.",

author = "C. Paz-Soldan and Cooper, \{C. M.\} and P. Aleynikov and Eidietis, \{N. W.\} and A. Lvovskiy and Pace, \{D. C.\} and Brennan, \{D. P.\} and Hollmann, \{E. M.\} and C. Liu and Moyer, \{R. A.\} and D. Shiraki",

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doi = "10.1063/1.5024223",

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T1 - Resolving runaway electron distributions in space, time, and energy

AU - Paz-Soldan, C.

AU - Cooper, C. M.

AU - Aleynikov, P.

AU - Eidietis, N. W.

AU - Lvovskiy, A.

AU - Pace, D. C.

AU - Brennan, D. P.

AU - Hollmann, E. M.

AU - Liu, C.

AU - Moyer, R. A.

AU - Shiraki, D.

PY - 2018/5/1

Y1 - 2018/5/1

N2 - Areas of agreement and disagreement with present-day models of runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from runaway electrons (REs) with a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent RE transport, and can be used to perform full two-dimensional (energy and pitch-angle) inversions of the RE phase-space distribution. Energy-resolved measurements find qualitative agreement with modeling on the role of collisional and synchrotron damping in modifying the RE distribution shape. Measurements are consistent with predictions of phase-space attractors that accumulate REs, with non-monotonic features observed in the distribution. Temporally resolved measurements find qualitative agreement with modeling on the impact of collisional and synchrotron damping in varying the RE growth and decay rate. Anomalous RE loss is observed and found to be largest at low energy. Possible roles for kinetic instability or spatial transport to resolve these anomalies are discussed.

AB - Areas of agreement and disagreement with present-day models of runaway electron (RE) evolution are revealed by measuring MeV-level bremsstrahlung radiation from runaway electrons (REs) with a pinhole camera. Spatially resolved measurements localize the RE beam, reveal energy-dependent RE transport, and can be used to perform full two-dimensional (energy and pitch-angle) inversions of the RE phase-space distribution. Energy-resolved measurements find qualitative agreement with modeling on the role of collisional and synchrotron damping in modifying the RE distribution shape. Measurements are consistent with predictions of phase-space attractors that accumulate REs, with non-monotonic features observed in the distribution. Temporally resolved measurements find qualitative agreement with modeling on the impact of collisional and synchrotron damping in varying the RE growth and decay rate. Anomalous RE loss is observed and found to be largest at low energy. Possible roles for kinetic instability or spatial transport to resolve these anomalies are discussed.

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U2 - 10.1063/1.5024223

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SN - 1070-664X

VL - 25

JO - Physics of Plasmas

JF - Physics of Plasmas

IS - 5

M1 - 056105

ER -

Resolving runaway electron distributions in space, time, and energy

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