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McStas: Pol_Bfield Component

[ Identification | Description | Input parameters | Output parameters | Links ]

The Pol_Bfield Component

Magnetic field component.

Identification

  • Author: Erik B Knudsen, Peter Christiansen and Peter Willendrup
  • Origin: RISOE
  • Date: July 2011
  • Version:(Unknown)

Description


Region with a definable magnetic field.

The component is nestable. This means that it requires a

// START MAGNETIC FIELD
COMPONENT msf =
Pol_Bfield(xwidth=0.08, yheight=0.08, zdepth=0.2, Bx=0, By=-0.678332e-4, Bz=0)
     AT (0, 0, 0) RELATIVE armMSF

// HERE CAN BE OTHER COMPONENTS INSIDE THE MAGNETIC FIELD

// STOP MAGNETIC FIELD
COMPONENT msf_stop = Pol_simpleBfield_stop(magnet_comp_stop=msf)
     AT (0, 0, 0) RELATIVE armMSF

In between the two component instances the propagation routine
PROP_DT also handles spin propagation.
The current algorithm used for spin propagation is:
SimpleNumMagnetPrecession
in pol-lib.

Example: Pol_Bfield(xwidth=0.1, yheight=0.1, zdepth=0.2, Bx=0, By=1, Bz=0)
         Pol_Bfield(xwidth=0.1, yheight=0.1, zdepth=0.2,
           filename="bfield.dat", fieldFunction=table_magnetic_field)

The magetic field may be given as any definable c-function with a specific footprint:
  int func(double x, double y, double z, double t, double *bx, double *by, double *bz, void *data)
where the magnetic field at coordinates (x,y,z, t) is returned in the variables
pointed to by bx,by, and bz. Additional parameters to be handed to the function
should be handed to the function using the pointer data.

Functions supplied by the system are:
1. const_magnetic_field: Constant field (Bx,By,Bz) within the region
2. rot_magnetic_field: Field is initially (0,By,0) but after a length of zdepth
     has rotated to (By,0,0)
3. majorana_magnetic_field: Field is initially (Bx,By,0) liearly transforms to
     (-Bx,By,0) after zdepth where By<

Input parameters

Parameters in boldface are required; the others are optional.
Name Unit Description Default
fieldFunction pointer Function describing the magnetic field. const_magnetic_field
field_prms NULL
xwidth m Width of opening. 0
yheight m Height of opening. 0
zdepth m Length of field. 0
radius m Radius of field if it is cylindrical or spherical. 0
Bx T Parameter used for x composant of field. 0
By T Parameter used for y composant of field. 0
Bz T Parameter used for z composant of field. 0
filename File where the magnetic field is tabulated. "bfield.dat"
geometry NULL
concentric Allow components and/or other fields inside field. Requires a subsequent Pol_simpleBfield_stop component. 1

Output parameters

Name Unit Description Default
magnet  
parPtr pointer Pointer to component magnet parameters.  
prms Structur containing the shape of the magnetic field.  

Links


[ Identification | Description | Input parameters | Output parameters | Links ]

Generated automatically by McDoc, Peter Willendrup <peter.willendrup@risoe.dk> / Fri Jan 18 10:06:09 2019


Last Modified: Friday, 18-Jan-2019 11:06:09 CET
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