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Finding the Source of Ion Beams in the Solar Wind

Finding the Source of Ion Beams in the Solar Wind. Hanna Kristensen Advisors: Justin Kasper and Mike Stevens. Solar Wind. Plasma frozen into magnetic field lines (by the Lorentz Force) The proton density, velocity, temperature vary n ~ a few cm -3 v ~ hundreds of km/ s w ~ tens of km/ s

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Finding the Source of Ion Beams in the Solar Wind

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  1. Finding the Source of Ion Beams in the Solar Wind Hanna Kristensen Advisors: Justin Kasper and Mike Stevens

  2. Solar Wind • Plasma frozen into magnetic field lines (by the Lorentz Force) • The proton density, velocity, temperature vary • n~ a few cm-3 • v~ hundreds of km/s • w~ tens of km/s • Usually not in thermodynamic equilibrium!

  3. Maxwell distribution

  4. Maxwell distribution

  5. Magnetic Reconnection

  6. Reconnection Sites Gosling et al., 2005

  7. Wind Faraday Cup • Sitting at the first LaGrange point • Spinning at 3 second period • 2 Faraday cups (one tilted up and one down) SWE

  8. Data Collection

  9. March 25, 1998 Bz[nT] By [nT] Bx[nT] 15:45 16:00 16:15 16:30 16:45 15:45 16:00 16:15 16:30 16:45 15:45 16:00 16:15 16:30 16:45 vz[km/s] vy[km/s] vx[km/s] 15:45 16:00 16:15 16:30 16:45 15:45 16:00 16:15 16:30 16:45 15:45 16:00 16:15 16:30 16:45 (red points signify a beam detected)

  10. Density in the exhaust

  11. Transformation Out-of-plane speed [km/s] Inflow speed [km/s] Outflow speed [km/s]

  12. Fits Ion Flux Distribution for March 25, 1998; 16:21

  13. Relationship between inflow speed and Δv

  14. Differential flow vs. Alfvén speed

  15. Plasma Instabilities

  16. Instability Evolution • Configurations with ∆v››vAare unstable! • Beam loses energy to Alfvénic fluctuations • Waves become stronger • Waves scramble the structure • Growth rate is faster than the time it takes plasma to cross the exhaust Yoshiharu Omuraand Koichi Shin 
Research Institute for Sustainable Humanosphere, Kyoto University

  17. Conclusions • Beams do develop in magnetic reconnection exhausts • Their speed actually exceeds the inflow speed • Acceleration process? • In some cases, an unstable beam-core configuration arises (Alfvén/Ion cyclotron mode)

  18. Acknowledgements • Dr. Michael Stevens and Dr. Justin Kasper • NSF (grant number AGS-1263241) • CFA • Dr. Kathy Reeves and Dr. Trae Winter • SSXG & Admins • Fellow astronomy and solar interns

  19. Questions • What is the process that accelerates the beams faster than the inflow? • How does the instability affect the evolution of reconnection exhausts

  20. Much of the solar wind has Alfvénic beams of coronal origin This is the stuff we think reconnection might explain We actually found this stuff in some reconnection exhausts

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