Joule Heating and Ampère’s force law

30 11 2008

I’ve completed a first attempt at coding calculations for Joule Heating and Ampère’s force law. Joule Heating tells us how hot the copper coil will get when we pass a currant through it. Ampère’s force law tells us the mechanical force the coils exert on the chassis. No idea if these calculations are correct, going to review them with someone who knows better.  A shout out to ruby-units, this rubygem makes working with physical units very easy. Here is the source code for the calculations

Here are the calculations for the current dimentions:

  • outside_radius: 242.487113059643 mm
  • wraps: 225
  • torus_midplane_radius: 192.693468865964 mm
  • donut_exterier_radius: 107.94 mm
  • torus_radius: 84.14 mm
  • donut_hole_radius: 60.34 mm
  • torus_tube_radius: 23.8 mm
  • torus_tube_hollow_radius: 18.802 mm
  • joint_radius: 16.66 mm
  • joint_negative_radius: 5.831 mm
  • torus_tube_wall_thickness: 4.998 mm


Joule Heating

  • drive_amps: 2000 A
  • coil_length: 116507 mm
  • specific_heat_of_copper: 24.44 J/mol*degK
  • atomic_weight_of_copper: 63.546 g/mol
  • coil_weight_in_moles: 53.9277 mol
  • coil_weight: 3426.89 g
  • wire_resistance: 5.21096e-06 Ohm/mm
  • coil_resistance: 0.607114 Ohm
  • joule_heating: 1842.54 degK


Ampère’s force law. I simplified the model. I’m calculating the force between two coils at a distance equal to the torus_midplane_radius.

  • magnetic_constant: 1.25664e-06 N/A^2
  • magnetic_force_constant: 2e-07 N/A^2
  • seperation_of_wires: 0.192693 m
  • coil_force_per_meter: 4.15167 N/m
  • coil_force: 483.7 N



One response

30 12 2008
Finite Element Analysis « Prometheus Fusion Perfection

[…] did some crude calculations for the force from the coils. Now we need to calculate the strength of the chassis […]

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