DRACO Research Update Surface Interactions

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DRACO Research UpdateSurface Interactions

• November 8, 2005
• A Presentation By
• Randy Spicer

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What Does DRACO Do Now?
External
Internal

• DRACO does not have any surface interaction
  subroutines
• When a particle hits a surface the particle is
  removed from the simulation
• The particles charge and energy disappear from
  the simulation as well
• This is obviously wrong

Poof

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What Should DRACO Do?
Before
After

• Particles should deposit charge on the spacecraft
• Particles can collide elastically
• Particles can be deposited on surface
• Particles can cause sputtering

F
F
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How Can DRACO Do This?

• The first step in performing surface interactions
  is to determine what surface the particles
  collide with
• DRACO knows if the Cartesian cells are
  Internal, External or Interface and removes
  particles based on their location in these cells
  and the tetrahedrals
• DRACO must be modified to determine which surface
  the particle collided
• For Interface Cells, the interface tets know what
  surface they were created from
• For Internal Cells, the particles must be matched
  with an interface cell

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What Am I Doing?

• Determines if particle is in an internal or
  interface Cell
• Internal
• Use Bisection method until in Interface Cell
• Interface
• Determine what Tet the particle is in
• If Interface Tet, determine surface
• If Internal Tet, use Bisection method until in
  interface Tet
• Move particle back to surface
• Determine surface normal and determine what
  interaction should be preformed
• Perform Interaction

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What Must Still Be Done?

• Determining Surface Subroutine at 50
• Lubos Eventually Wants to use Line-Triangle
• Subroutine for determining what interaction to
  perform has not been started yet
• Interactions must be coded
• Alex is working on Charging
• Some Sputtering in DRACO that must be modified
• Elastic collisions and depositing partially coded
  by Lubos
• Code-testing / Simulations / Paper-writing

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Questions?