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Title: Particle orbits in a force-balanced, wave-driven, rotating torus

Authors:
ORCiD logo [1]; ORCiD logo [1]
  1. Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08540, USA, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1389120
Grant/Contract Number:
FG02-97ER25308; SC0016072
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 9; Related Information: CHORUS Timestamp: 2018-02-14 15:09:52; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Ochs, I. E., and Fisch, N. J. Particle orbits in a force-balanced, wave-driven, rotating torus. United States: N. p., 2017. Web. doi:10.1063/1.4991510.
Ochs, I. E., & Fisch, N. J. Particle orbits in a force-balanced, wave-driven, rotating torus. United States. doi:10.1063/1.4991510.
Ochs, I. E., and Fisch, N. J. 2017. "Particle orbits in a force-balanced, wave-driven, rotating torus". United States. doi:10.1063/1.4991510.
@article{osti_1389120,
title = {Particle orbits in a force-balanced, wave-driven, rotating torus},
author = {Ochs, I. E. and Fisch, N. J.},
abstractNote = {},
doi = {10.1063/1.4991510},
journal = {Physics of Plasmas},
number = 9,
volume = 24,
place = {United States},
year = 2017,
month = 9
}

Journal Article:
Free Publicly Available Full Text
This content will become publicly available on September 11, 2018
Publisher's Accepted Manuscript

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  • We present the results of a numerical investigation of droplets walking on a rotating vibrating fluid bath. The drop's trajectory is described by an integro-differential equation, which is simulated numerically in various parameter regimes. As the forcing acceleration is progressively increased, stable circular orbits give way to wobbling orbits, which are succeeded in turn by instabilities of the orbital center characterized by steady drifting then discrete leaping. In the limit of large vibrational forcing, the walker's trajectory becomes chaotic, but its statistical behavior reflects the influence of the unstable orbital solutions. The study results in a complete regime diagram thatmore » summarizes the dependence of the walker's behavior on the system parameters. Our predictions compare favorably to the experimental observations of Harris and Bush [“Droplets walking in a rotating frame: from quantized orbits to multimodal statistics,” J. Fluid Mech. 739, 444–464 (2014)].« less
  • The inspiral of a stellar compact object into a massive black hole, an extreme-mass-ratio inspiral, is one of the main sources of gravitational waves for the future space-based Laser Interferometer Space Antenna. We expect to be able to detect and analyze many cycles of these slowly inspiraling systems, which makes them truly high-precision tools for gravitational-wave astronomy. To that end, the use of very precise theoretical waveform templates in the data analysis is required. To build them, we need to have a deep understanding of the gravitational backreaction mechanism responsible for the inspiral. The self-force approach describes the inspiral asmore » the action of a local force that can be obtained from the regularization of the perturbations created by the stellar compact object on the massive black hole geometry. In this paper we extend a new time-domain technique for the computation of the self-force from the circular case to the case of eccentric orbits around a nonrotating black hole. The main idea behind our scheme is to use a multidomain framework in which the small compact object, described as a particle, is located at the interface between two subdomains. Then, the equations at each subdomain are homogeneous wave-type equations, without distributional sources. In this particle-without-particle formulation, the solution of the equations is smooth enough to provide good convergence properties for the numerical computations. This formulation is implemented by using a pseudospectral collocation method for the spatial discretization, combined with a Runge-Kutta algorithm for the time evolution. We present results from several simulations of eccentric orbits in the case of a scalar charged particle around a Schwarzschild black hole, an excellent test bed model for testing the techniques for self-force computations. In particular, we show the convergence of the method and its ability to resolve the field and its derivatives across the particle location. Finally, we provide numerical values of the self-force for different orbital parameters.« less
  • Experiments in the National Spherical Torus Experiment [M. Ono et al., Nucl. Fusion 40, 557 (2000)] have yielded new, unique observations of nonlinear three-wave interactions between compressional Alfven eigenmodes (CAEs) and other fast-ion driven instabilities. Specifically, nonlinear interactions of CAEs have been conclusively identified with both energetic particle modes (EPMs) and toroidicity-induced Alfven eigenmodes (TAEs). These nonlinear interactions occur simultaneously with other three-wave interactions observed between the TAEs and EPMs [N. A. Crocker et al., Phys. Rev. Lett. 97, 045002 (2006)]. The interaction between the CAEs and EPMs spatially redistributes the energy of the CAEs, concentrating it into a toroidallymore » localized wave packet in the same way that the interaction between the TAEs and EPMs spatially concentrates the energy of the TAEs. The interaction between the CAEs and TAEs has been shown to further subdivide the CAE wave packet into a train of smaller wave packets. These nonlinear interactions occur during fast-ion loss events. The spatial redistribution of CAE fluctuation energy will modify the effect of the CAEs on fast-ion transport during these events.« less