Characterizing the Interaction between Whistler-Mode Chorus and Energetic Electrons via Test Particle Simulations

Talk presented at 2016 Mini-GEM Meeting, San Francisco, CA, December, 2016

Transcript

1. Characterizing the interaction between whistler-mode chorus and energetic electrons via test particle simulations Caitano L. da Silva, Richard E. Denton, Mary K. Hudson, Robyn M. Millan Department of Physics & Astronomy Dartmouth College Mini-GEM Workshop December 11, 2016, San Francisco, CA
2. Waves in the Inner Magnetosphere 2 Thorne et al. [2016]
3. Waves in the Inner Magnetosphere 3 Motivation: “Understanding acceleration and loss mechanisms of radiation belt electrons due to whistler-mode chorus”
4. Simulation of Whistler-Mode Chorus 4 0.92 0.96 1 1.04 1.08 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Curvilinear Coordinates Dawn Noon Pure Dipole Field (b1 =0) Compressed Dipole Field (b1 =1.6B0) (a) (b) (c) Coordinate System da Silva et al. [JGR, In Press, 2016]
5. 5 0.92 0.96 1 1.04 1.08 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 0 0.2 0.4 0.6 0.8 1 Curvilinear Coordinates Dawn Noon Pure Dipole Field (b1 =0) Compressed Dipole Field (b1 =1.6B0) (a) (b) (c) Ring Current Electrons da Silva et al. [JGR, In Press, 2016] Simulation of Whistler-Mode Chorus 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1 1.5 2 2.5 3 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 0.01 0. 0.92 0.94 0.96 (a) (b) (c) 0.05 0.06 0.07 0.08 1 1.02 1.04 1.06 1.08 1 1.5 2 2.5 3 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 0° 5° 10° 15° 20° 25° 30° 0.01 0.02 0.03 0.04 0.05 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 (b) (c) Anisotropy
6. Model Formulation 6 Coupling Particles Fluid References: Hu and Denton [JGR, 114, A12217, 2009] Wu et al. [JGR, 120(3), 1908, 2015] da Silva et al. [JGR, In Press, 2016] Hybrid Fluid/Particle Simulation Approach
7. Wave Development 7 -0.04 -0.02 0 0.02 0.04 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 0° 5° 10° 15° 20° 25° 30° -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.92 0.94 0.96 0.98 1 1.02 1.04 1.06 1.08 (a) 200 (b) 300 (c) 400 0 1 2 3 4 5 6 7 0 - 100 100 - 200 200 - 300 300 - 400 4.5 5 0 1 2 3 4 5 6 7 8 9 7 (a) ( (c) ( Pure Dipole Field (b1 =0) 0 1 2 3 4 5 6 7 0 - 100 100 - 200 200 - 300 300 - 400 0 0.2 0.4 0.6 0.8 1 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 0 1 2 3 4 5 6 7 8 9 0 0 1 2 3 4 5 6 7 (a) ( (c) ( Pure Dipole Field (b1 =0) -3 -2 -1 0 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 -3 -2 -1 0 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0 20 40 60 80 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0 0.2 0.4 0.6 0.8 0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0 0.2 0.4 0.6 0.8 1 -0.04 -0.02 0 0.02 0.04 (d) (c) (b) (a) Linear Dispersion Analysis: Growth Rate Spectrum Hybrid-Code Simulations
8. Pitch-Angle Scattering, 100 keV electrons 8 0 100 200 300 400 0 20 40 60 80 100 120 140 160 180 -3 -2 -1 0 1 2 3 n = -1 n = 0 n = 1 n = 2 n = 3 -1.5 -1 -0.5 0 0.5 1 0 5 10 0 20 40 60 80 100 120 140 160 180 0 100 200 300 400 0 1 2 3 4 Maxwellian Resonance Curves
9. Energy Changes, 100 keV electrons 9 0 100 200 300 400 0 20 40 60 80 100 120 140 160 180 -4 -3 -2 -1 0 1 2 3 4 n = -1 n = 0 n = 1 n = 2 n = 3 -1.5 -1 -0.5 0 0.5 1 0 2 4 0 20 40 60 80 100 120 140 160 180 0 100 200 300 400 0 5 10 15
10. Pitch-Angle Scattering, 1 MeV electrons 10 0 1 2 3 4 0 20 40 60 80 100 120 140 160 180 -4 -3 -2 -1 0 1 2 3 4 n = -7 n = -5 n = -3 n = -1 n = 0 n = 1 n = 3 n = 5 n = 7 n = 9 -3 -2.5 -2 -1.5 -1 -0.5 0 0.5 0 0.5 1 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 0 0.2 0.4 0.6 0.8 Maxwellian Resonance Curves:
11. Energy Changes, 1 MeV electrons 11 0 1 2 3 4 0 20 40 60 80 100 120 140 160 180 -0.015 -0.01 -0.005 0 0.005 0.01 0.015 n = -7 n = -5 n = -3 n = -1 n = 0 n = 1 n = 3 n = 5 n = 7 n = 9 -2 -1.5 -1 -0.5 0 0.5 0 0.1 0.2 0 20 40 60 80 100 120 140 160 180 0 1 2 3 4 0 0.1 0.2 0.3 0.4 0.5
12. Summary 12 • Predominant energy and pitch-angle changes are easily explained by first harmonic resonance (n=1) for counterstreaming electrons and by Landau resonance (n=0) for costreaming electrons. • Significant pitch-angle scattering at high energies does not seem to be compatible with resonant interactions. • Further information: da Silva, C. L., S. Wu, R. E. Denton, M. K. Hudson, R. M. Millan, Hybrid Fluid-Particle Simulation of Whistler-Mode Waves in a Compressed Dipole Magnetic Field: Implications for Dayside High-Latitude Chorus, Accepted for publication in J. Geophys. Res., doi:10.1002/2016JA023446.
13. Thank you! Contact: caitano.dasilva@dartmouth.edu
14. Extra Slide 14 Maxwellian
15. Extra Slide E (MeV) 0 1 2 3 4 100 E (MeV) 0 1 2 3 100 E (MeV) 0 1 2 3 4 Normalized Spectrum 10-4 10-3 10-2 10-1 100 Precipitation Initially trapped E (MeV) 0 1 2 3 Precipitation Probability ×10-3 0 1 2 3 4 5 15 Maxwellian