Whistler turbulence heating of electrons and ions: Three-dimensional particle-in-cell simuations
- Space Science Institute, Boulder, CO (United States)
- Univ. of Southern California, Los Angeles, CA (United States)
In this study, the decay of whistler turbulence in a collisionless, homogeneous, magnetized plasma is studied using three-dimensional particle-in-cell simulations. The simulations are initialized with a narrowband, relatively isotropic distribution of long wavelength whistler modes. A first ensemble of simulations at electron beta $${\beta }_{{\rm{e}}}$$ = 0.25 and ion-to-electron mass ratio $${m}_{{\rm{i}}}$$/$${m}_{{\rm{e}}}$$ = 400 is carried out on a domain cube of dimension $$L{\omega }_{\mathrm{pi}}$$/c = 5.12 where $${\omega }_{\mathrm{pi}}$$ is the ion plasma frequency. The simulations begin with a range of dimensionless fluctuating field energy densities, $${\epsilon }_{{\rm{o}}}$$, and follow the fluctuations as they cascade to broadband, anisotropic turbulence which dissipates at shorter wavelengths, heating both electrons and ions. The electron heating is stronger and preferentially parallel/antiparallel to the background magnetic field $${{\boldsymbol{B}}}_{{\rm{o}}};$$ the ion energy gain is weaker and is preferentially in directions perpendicular to $${{\boldsymbol{B}}}_{{\rm{o}}}$$. The important new results here are that, over 0.01 < $${\epsilon }_{{\rm{o}}}$$ < 0.25, the maximum rate of electron heating scales approximately as $${\epsilon }_{{\rm{o}}}$$, and the maximum rate of ion heating scales approximately as $${\epsilon }_{{\rm{o}}}^{1.5}$$. A second ensemble of simulations at $${\epsilon }_{{\rm{o}}}$$ = 0.10 and $${\beta }_{{\rm{e}}}$$ = 0.25 shows that, over 25 < $${m}_{{\rm{i}}}$$/$${m}_{{\rm{e}}}\;$$< 1836, the ratio of the maximum ion heating rate to the maximum electron heating rate scales approximately as $${m}_{{\rm{e}}}$$/$${m}_{{\rm{i}}}$$.
- Research Organization:
- Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC52-06NA25396
- OSTI ID:
- 1255083
- Report Number(s):
- LA-UR-15-27211
- Journal Information:
- The Astrophysical Journal (Online), Vol. 816, Issue 2; ISSN 1538-4357
- Publisher:
- Institute of Physics (IOP)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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