期刊
JOURNAL OF COMPUTATIONAL PHYSICS
卷 418, 期 -, 页码 -出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcp.2020.109639
关键词
Asymptotic preserving; Charged particle orbit; Implicit; Energy conserving
资金
- U.S. Department of Energy [DE-AC52-07NA27344, DE-AC52-06NA25396]
- Exascale Computing Project, a collaborative effort of the U.S. Department of Energy Office of Science [17-SC-20-SC]
- National Nuclear Security Administration
- DOE Office of Applied Scientific Computing Research
We present a new implicit asymptotic preserving time integration scheme for charged-particle orbit computation in arbitrary electromagnetic fields. The scheme is built on the Crank-Nicolson integrator and continues to recover full-orbit motion in the small time-step limit, but also recovers all the first-order guiding center drifts as well as the correct gyroradius when stepping over the gyration time-scale. In contrast to previous efforts in this direction, the new scheme also features exact energy conservation. In the derivation of the scheme, we find that a new numerical time-scale is introduced. This scale is analyzed and the resulting restrictions on time-step are derived. Based on this analysis, we develop an adaptive time-stepping strategy the respects these constraints while stepping over the gyration scale when physically justified. It is shown through numerical tests on single-particle motion that the scheme's energy conservation property results in tremendous improvements in accuracy, and that the scheme is able to transition smoothly between magnetized and unmagnetized regimes as a result of the adaptive time-stepping. (C) 2020 Elsevier Inc. All rights reserved.
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