Yang Henglei(???),Wang Xiaogang(???)

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Effects of Inflow Disturbance at Boundaries on
the Magnetic Reconnection

• Yang Henglei(???),Wang Xiaogang(???)
• State Key Laboratory of Materials Modification by
  Laser, Ion and Electron Beams
• The Department of Physics
• Dalian University of Technology

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Outline

• Driven reconnection
• Model
• Simulation results
• Summary and discussions

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• Magnetic reconnection usually happens in the
  magnetic confined plasmas as well as the
  planetary space plasma
• Magnetic fields embedded in plasmas undergo
  topological rearrangement due to nonideal
  instabilities or perturbations imposed at the
  boundary free or driven
• Liberate free energy that can be converted to
  thermal and kinetic energy.

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The sketch of reconnection
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Ohms Law

• Collisional Ohms law

• Generalized Ohms Law

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Outline

• Driven reconnection
• Model
• Simulation results
• Summary and discussions

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Taylor model (Classical driven reconnection
model)
Fundamental model proposed by Taylor, and
investigated by Hahm and Kulsrud
is subjected to a boundary deformation
Xiaogang Wang .etc have made some researches and
corrections on the model in the early work
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z
y ?
x
2Lc
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Model (2 D 3 components MHD)
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The initial magnetic fields
and
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• The boundary conditions

• At z0, the symmetric boundary conditions are
  taken use of

• Along the x direction, the periodical boundary
  conditions are imposed, i.e. the variables at
  the left boundary (x0) correspond with the
  values at the right boundary (xLx2)

• , an inflow (in the
  units of ) is imposed

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Fig. The inflow disturbance configuration
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Outline

• Driven reconnection
• Model
• Simulation results
• Summary and discussions

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CASE 1
is changed orderly
Fig. the magnetic field figure when
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Reconnection has happened
Fig. the magnetic field figure (a) and velocity
vector figure (b) at t82 when
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Fig. time history of magnetic reconnection rate
trend under the different inflow velocities
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CASE 2
is changed orderly
Fig. the magnetic field figure (a) and velocity
vector figure (b) at t60 when
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CASE 3
is changed orderly
Fig. Comparison of the magnetic fields figures
when
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CASE 4
is changed orderly
Fig. Comparison of the magnetic fields figures
when
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Outline

• Driven reconnection
• Model
• Simulation results
• Summary and discussions

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Summary

• 1) The faster the at boundaries is,
• 2) the closer its position (i.e. here) to the
  current sheet is,
• 3) the lower the viscosity is,
• 4) the higher the resistivity is,
• The faster the reconnection rate will be.

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Discussion

• The forced reconnection is caused by the driven
  inflow at the boundaries which bring the magnetic
  flux in as
• Owing to the resistivity in the current
  sheet, the magnetic lines are cut and reconnected
  again, and the magnetic islands are formed.

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Discussion

• Reconnection is flow driven, increasing the
  inflow value and decreasing its distance to the
  current sheet will enhance its influence on
  reconnection
• Furthermore the viscosity slows down the flow,
  therefore, reducing viscosity will strengthen the
  flow effect.
• Finally, the resistivity provides the
  dissipation, thus the larger the resistivity is,
  the easier the field lines reconnect.

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THANK YOU
The end