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Acceleration of Solar Energetic Particles

Acceleration of Solar Energetic Particles. Rami Vainio University of Helsinki, Department of Physics, Finland University of Turku, Department of Physics and Astronomy, Finland. SPACECAST Stakeholder Meeting , BAS, 7 February 2014. Solar energetic particle events. Lario (2005).

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Acceleration of Solar Energetic Particles

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  1. Acceleration of Solar Energetic Particles Rami Vainio University of Helsinki, Department of Physics, Finland University of Turku, Department of Physics and Astronomy, Finland SPACECAST Stakeholder Meeting, BAS, 7 February 2014

  2. Solar energetic particle events Lario (2005)

  3. Flares or shocks? Large gradual SEP events nearly always accompanied with both! –30 min

  4. Solar energetic particle events Lario (2005)

  5. Present paradigm of SEP acceleration in gradual events CME-driven shocks are the mainsource of deka-MeV protons duringthe largest SEP events

  6. CME driven shocks

  7. Diffusive shock acceleration u2 SW frame u1 ∆u = u2 – u1

  8. Turbulent foreshock Outward-streaming ions scattering off turbulence leadto amplification of fluctuationsBootstrapping!

  9. Modeling in SPACECAST Proton intensity [cm–2sr–1 s–1 MeV–1] Alfvén wave intensity [G2] Distance of the shock from the Sun = 14 – 22 R

  10. Mathematical model (—) developedfor turbulent region explainssimulations (- - -) Three different initial particle distributions 1b 1a 1c R= 5.8–11 R θBn = 2.8°Vs = 1920 km/s  2b 2a 2c R= 14–22 R θBn = 5.4°Vs = 1820 km/s  3b 3a 3c R= 25–36 R θBn = 8.7°Vs = 1620 km/s  4b R= 40–60 R θBn = 14°Vs = 1430 km/s 4a 4c  New tool for space weather modelling

  11. Summary • Solar energetic particles are accelerated in flares and CME-driven shocks • CME-driven shocks responsible for large gradual events • SPACECAST project has developed models for particle acceleration in CME-driven shocks • First steps taken towards operational direction by analyzing simulations and developing a semi-analytical description of ion foreshocks in CMEs • Next steps: integration of SPACECAST results to a state-of-the-art transport code (see Angels Aran’s presentation)

  12. Acknowledgements • The research leading to these results has received funding from the European Union Seventh Framework Programme (FP7/2007-2013) under grant agreement no 262468, and is supported in part by the University of Helsinki

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