W. Scales, J. Wang, C. Chang Center for Space Science and Engineering Research Virginia Tech

1. Hybrid Simulation of Ion-Cyclotron Turbulence Induced by Artificial Plasma Cloud in the Magnetosphere Progress Report: W. Scales, J. Wang, C. Chang Center for Space Science and Engineering Research Virginia Tech

2. Outline • I. Introduction • II. Hybrid PIC Simulation Model • III. Simulation Results • IV. Summary and Conclusion

3. I. Introduction • Objective: • To study the process and efficiency of energy extraction from a chemical release that may produce plasma turbulence which ultimately interacts with radiation belt electrons • Overview of Progress: • Developed and implemented a new EM hybrid PIC algorithm which incorporates finite electron mass • Developing a new ES hybrid PIC algorithm which incorporates finite electron mass • Simulated plasma turbulence generated by the injection of a velocity ring distribution of Li ions • Simulation results show that the excitation of Lithium cyclotron harmonics which extracts about ~20% to ~15% of the Lithium ring energy (for nLi/nH ~5% to 20% injection)

4. II. EM Hybrid PIC Simulation Model • Basic Assumption: • Quasi-neutral plasma; particle ions; fluid electrons; • displacement current ignored • Governing Equations: • Fields: • Fluid Electrons: • Particle Ions

5. Electric field equation incorporating finite-mass electron mass Ignoring the velocity convection term: Initial goal is to study process proposed by Ganguli et al. 2007

6. III. Simulation Results • Simulation Initialization: • Injected Lithium ion: ring velocity distribution vmax=7km/s, the orbit velocity at the ejection ring energy=1.75eV • ambient hydrogen ion and electrons: Maxwellian distribution T=0.3eV • Simulation Cases: • nLi/nH=0%, 5%, 10%, 20%

7. Simulation domain • 2-D, Z is parallel to Bo , X is perpendicular to Bo • Zmax=182.42 km, 100 cells in the domain • Xmax=0.58 km, 50 cells in the domain • The Lithium Larmor radius=0.126 km. Xmax~ 4.6 times Larmor radius (11 cells for one Larmor radius)

8. Time History of Field Energy nLi/nH=0% nLi/nH=5% nLi/nH=20% nLi/nH=10% Saturation occurs after ~2.5*(2π/ linear growth rate)

9. Linear Growth Rate nLi/nH=5%

10. Frequency Spectrum Analysis: nLi/nH=5%:

11. k Spectrum Analysis: nLi/nH=5%

12. Lithium ion ring velocity phase: nLi/nH=5%

13. Lithium & Hydrogen ion velocity distribution: nLi/nH=5% Li+ H+

14. Energy Extraction Efficiency H+ KE change Li+ KE change Energy Extraction Efficiency=1-(Li+ kinetic energy)/(Li+ initial kinetic energy)

15. Significant progresses have been made in developing a simulation model of ion cyclotron turbulence generated by a velocity ring distribution Initial simulation predictions of energy extraction efficiency are consistent with predictions from previous work (Mikhailovskii et al., 1989) Model may be used to study a variety of velocity ring EM instability mechanisms from various chemical releases (Li, Ba, ect.) Future work Refine the current electromagnetic EM hybrid PIC code for more direct comparisons of the NRL mechanism Complete the implementation of a electrostatic ES hybrid PIC model with electron inertia for studying energy extraction associated with lower hybrid turbulence from chemical release (both Ba and Li). V. Summary and Future Plans

16. Historical Plot of Magnetic Field

17. Historical Plot of Electric Field

18. Normalized Governing Equations Fields: Particles: Where:

19. Numerical Implementation:Predictor Corrector Scheme Leapfrog Particle Push; PCG Electric Field Solver • The basic procedure are in four steps: