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Nature of 3D Magnetic Reconnection at Null Points. David Pontin Solar and Magnetospheric MHD Theory Group University of St. Andrews Collaborators: Eric Priest (St. Andrews) Gunnar Hornig (Bochum) St Andrews 8 th September 2003. B line velocity w , s.t.
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Nature of 3D Magnetic Reconnection at Null Points David Pontin Solar and Magnetospheric MHD Theory Group University of St. Andrews Collaborators: Eric Priest (St. Andrews) Gunnar Hornig (Bochum) St Andrews 8th September 2003
Bline velocity w, s.t. Bline mapping not continuous: break in diffusion region at X-point only. 1-1 correspondence of reconnecting Blines. 2D Reconnection: basic properties
in general now s.t. Blines followed through D do not move at v outside D. Blines continually change their connections in D. 3D Rec.: No w for isolated diffusion region (D)
3D Rec. at null points- ideal Ideal: spine rec. fan rec. flow imposed across: fan spine
Analytical examples • Solve kinematic steady resistive MHD eq.s: Resistive Ohm’s law Remaining Maxwell’s eq.s; t-independent • Impose deduce • Assume localised
Resistive spine rec. Impose: Influence of
v and w flows • Induced plasma flow rotational: • Add stag. pt. flow to see global effect. separatrices in z-const. plane:
Flux tube rec.: J parallel to spine • Tubes split entering D, flip, but do not rejoin. • No v across spine/fan
Resistive fan rec. • Impose:
Flux tube rec.: J parallel to fan Split, flip, no rejoin. Flux transported across fan at fan at finite rate.
Summary • Different structures of rec. at 3D nulls- very different from 2D. • Plan further analysis of fan rec. • Need to move to more realistic dynamical models: numerical expts. • The End.