Lifetime and universal distribution of seed runaway electrons
Abstract
The lifetime of pre-existing runaway electrons determines how likely the runaways will undergo avalanche multiplication. We estimate the lifetime of runaway electrons via kinetic analysis. We show that the rate of runaway decay depends on the combination of parameters α≡(Z+1)/$$\sqrt{{\bar{τ}}_{rad}}$$ (where $$τ_{rad}$$ is the synchrotron timescale normalized to the collisional timescale and Z is the ion charge) compared to the electric field. We identify two cases where the decay rate is slow enough to enable a quasi-steady shape of the runaway distribution function. This distribution and its lifetime represent the eigenfunction and the lowest eigenvalue of the kinetic equation. In one case, α$$\ll$$1: the field required to sustain the pre-existing runaways is barely larger than the Connor-Hastie critical value. In the same manner as by Aleynikov and Breizman [Phys. Rev. Lett. 114, 155001 (2015)], we solve the kinetic equation perturbatively but extend the work to demonstrate that the lifetime grows exponentially with the field at a rate that depends on α. Finally, in the second case, α$$\gg$$1: the sustainment field is much greater than the Connor-Hastie value, and the largeness of the field in this case enables us to universalize the kinetic equation via the re-scaling procedure.
- Authors:
-
- Univ. of Texas, Austin, TX (United States). Inst. for Fusion Studies
- Publication Date:
- Research Org.:
- Univ. of Texas, Austin, TX (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC)
- OSTI Identifier:
- 1540126
- Alternate Identifier(s):
- OSTI ID: 1420640
- Grant/Contract Number:
- FG02-04ER54742; SC0016283
- Resource Type:
- Accepted Manuscript
- Journal Name:
- Physics of Plasmas
- Additional Journal Information:
- Journal Volume: 24; Journal Issue: 11; Journal ID: ISSN 1070-664X
- Publisher:
- American Institute of Physics (AIP)
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; Physics
Citation Formats
Fontanilla, Adrian K., and Breizman, Boris N. Lifetime and universal distribution of seed runaway electrons. United States: N. p., 2017.
Web. doi:10.1063/1.5001931.
Fontanilla, Adrian K., & Breizman, Boris N. Lifetime and universal distribution of seed runaway electrons. United States. https://doi.org/10.1063/1.5001931
Fontanilla, Adrian K., and Breizman, Boris N. Tue .
"Lifetime and universal distribution of seed runaway electrons". United States. https://doi.org/10.1063/1.5001931. https://www.osti.gov/servlets/purl/1540126.
@article{osti_1540126,
title = {Lifetime and universal distribution of seed runaway electrons},
author = {Fontanilla, Adrian K. and Breizman, Boris N.},
abstractNote = {The lifetime of pre-existing runaway electrons determines how likely the runaways will undergo avalanche multiplication. We estimate the lifetime of runaway electrons via kinetic analysis. We show that the rate of runaway decay depends on the combination of parameters α≡(Z+1)/$\sqrt{{\bar{τ}}_{rad}}$ (where $τ_{rad}$ is the synchrotron timescale normalized to the collisional timescale and Z is the ion charge) compared to the electric field. We identify two cases where the decay rate is slow enough to enable a quasi-steady shape of the runaway distribution function. This distribution and its lifetime represent the eigenfunction and the lowest eigenvalue of the kinetic equation. In one case, α$\ll$1: the field required to sustain the pre-existing runaways is barely larger than the Connor-Hastie critical value. In the same manner as by Aleynikov and Breizman [Phys. Rev. Lett. 114, 155001 (2015)], we solve the kinetic equation perturbatively but extend the work to demonstrate that the lifetime grows exponentially with the field at a rate that depends on α. Finally, in the second case, α$\gg$1: the sustainment field is much greater than the Connor-Hastie value, and the largeness of the field in this case enables us to universalize the kinetic equation via the re-scaling procedure.},
doi = {10.1063/1.5001931},
journal = {Physics of Plasmas},
number = 11,
volume = 24,
place = {United States},
year = {2017},
month = {11}
}
Search WorldCat to find libraries that may hold this journalWeb of Science
Works referenced in this record:
Disruption generated runaway electrons in TEXTOR and ITER
journal, March 1996
- Jaspers, R.; Cardozo, N. J. Lopes; Schuller, F. C.
- Nuclear Fusion, Vol. 36, Issue 3
Damping of relativistic electron beams by synchrotron radiation
journal, December 2001
- Andersson, F.; Helander, P.; Eriksson, L. -G.
- Physics of Plasmas, Vol. 8, Issue 12
Relativistic limitations on runaway electrons
journal, June 1975
- Connor, J. W.; Hastie, R. J.
- Nuclear Fusion, Vol. 15, Issue 3
Theory of Two Threshold Fields for Relativistic Runaway Electrons
journal, April 2015
- Aleynikov, Pavel; Breizman, Boris N.
- Physical Review Letters, Vol. 114, Issue 15
Electron and Ion Runaway in a Fully Ionized Gas. II
journal, January 1960
- Dreicer, H.
- Physical Review, Vol. 117, Issue 2
Electron and Ion Runaway in a Fully Ionized Gas. I
journal, July 1959
- Dreicer, H.
- Physical Review, Vol. 115, Issue 2
Momentum–space structure of relativistic runaway electrons
journal, June 1998
- Martı́n-Solı́s, J. R.; Alvarez, J. D.; Sánchez, R.
- Physics of Plasmas, Vol. 5, Issue 6
Marginal stability model for the decay of runaway electron current
journal, April 2014
- Breizman, Boris N.
- Nuclear Fusion, Vol. 54, Issue 7
Phase-space dynamics of runaway electrons in magnetic fields
journal, February 2017
- Guo, Zehua; McDevitt, Christopher J.; Tang, Xian-Zhu
- Plasma Physics and Controlled Fusion, Vol. 59, Issue 4
Zur Theorie des Durchgangs schneller Elektronen durch Materie
journal, January 1932
- Møller, Chr.
- Annalen der Physik, Vol. 406, Issue 5
Theory for avalanche of runaway electrons in tokamaks
journal, October 1997
- Rosenbluth, M. N.; Putvinski, S. V.
- Nuclear Fusion, Vol. 37, Issue 10
Works referencing / citing this record:
Spatial transport of runaway electrons in axisymmetric tokamak plasmas
journal, January 2019
- McDevitt, Christopher J.; Guo, Zehua; Tang, Xian-Zhu
- Plasma Physics and Controlled Fusion, Vol. 61, Issue 2
Physics of runaway electrons in tokamaks
journal, June 2019
- Breizman, Boris N.; Aleynikov, Pavel; Hollmann, Eric M.
- Nuclear Fusion, Vol. 59, Issue 8