simionx.MField - Biot-Savart magetic field calculations

SYNOPSIS

-- mag.lua (assumes workbench is similarly named mag.iob)
-- Example SIMION workbench program applying calculated
-- solenoid magnetic field.

simion.workbench_program()
local MField = require "simionx.MField"  -- load module

-- Define solenoid magnetic field.
local field = MField.solenoid_hoops {
  first  = MField.vector(-10,0,0),
  last   = MField.vector(-10,0,0)
  radius = 1.2,
  nturns = 200
}

-- Draw wires in SIMION 8.1
field:draw()

-- SIMION mfield_adjust segment overrides
-- magnetic fields in magnetic PA at current
-- particle position.
function segment.mfield_adjust()
  -- Calculate solenoid magnetic field at current
  -- particle position (with Biot-Savart calculation).
  ion_bfieldx_gu, ion_bfieldy_gu, ion_bfieldz_gu
    = field(ion_px_mm, ion_py_mm, ion_pz_mm)
end

DESCRIPTION

This module calculates various magnetic fields from wire currents using the Biot-Savart Law. The magnetic fields calculated can be used directly or, as often done, applied in a workbench via an mfield_adjust user program segment.

The module is loaded with

local MField = require "simionx.MField"

This module is typically used by first constructing an object defining the wire current configuration:

local field = MField.line_segment {
  current = 2,
  first = MField.vector(-50,0,0),
  last = MField.vector(50,0,0)
}

This defines an infinitely thin line segment of wire with 2 amps going from point (x,y,z) = (-50,0,0) to point (x,y,z) = (50,0,0) mm. It does not yet calculate the magnetic field though.

To calculate the magnetic field at some arbitrary point from this magnetic system, we call the object as a function, passing it the x, y, and z components of the observation point:

local bx, by, bz = field(0,0,1)
print(bx,by,bz)  --> 0 -3.99920023992 0

In SIMION 8.1.0, wires from the field object can be drawn on the View screen with the draw method:

field:draw()

The above does nothing in previous SIMION versions, but you can test whether it will do anything by checking the MField.can_draw boolean variable.

Note

See these additional sections in this topic in the offline SIMION 8.1.0 help file:

• INTERFACE

Changes

20110826 - Added mfield:draw method to draw wires on the SIMION View screen in SIMION 8.1.0.

SOURCE

(c) 2007-2011 Scientific Instrument Services, Inc. Licensed under the terms of SIMION 8.0/8.1. www.simion.com. D.Manura-200704.

version: 20110826