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Acceleration of Solar Energetic Particles Rami Vainio University of Helsinki, Department of Physics, Finland University of Turku, Department of Physics.

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Presentation on theme: "Acceleration of Solar Energetic Particles Rami Vainio University of Helsinki, Department of Physics, Finland University of Turku, Department of Physics."— Presentation transcript:

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 main source of deka-MeV protons during the largest SEP events

6 CME driven shocks

7 Diffusive shock acceleration ∆u = u 2 – u 1 SW frame u1u1 u2u2

8 Turbulent foreshock Outward-streaming ions scattering off turbulence lead to amplification of fluctuations Bootstrapping!

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

10 R = 5.8–11 R  θ Bn = 2.8° V s = 1920 km/s R = 14–22 R  θ Bn = 5.4° V s = 1820 km/s R = 25–36 R  θ Bn = 8.7° V s = 1620 km/s R = 40–60 R  θ Bn = 14° V s = 1430 km/s     1a 2a 3a 4a 1b 2b 3b 4b 1c 2c 3c 4c Three different initial particle distributions Mathematical model (—) developed for turbulent region explains simulations (- - -) 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/ ) under grant agreement no , and is supported in part by the University of Helsinki


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