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Trapped Radiation ENvironment model Development

UF420

[ Name | Synopsis | Arguments | Description | Diagnostics | Common Blocks | Dependencies | See Also | Reported Bugs | Examples ]

Name

    Subroutine UF420 - trace a magnetic field line segment passing through a given position

Synopsis

      INTEGER*4     nfbm, ifail
      REAL*8        fbm(nfbm), falt
      RECORD /zgeo/ mpos
      
      CALL UF420 (mpos, fbm, nfbm, falt, ifail)

Arguments

    mpos
    The geographic position (GEO) through which the searched magnetic field line is passing [in]
    fbm
    Boundary conditions on the magnetic field intensity [in]
    nfbm
    Number of boundary conditions on the magnetic field intensity [in]
    falt
    Boundary condition on the altitude [in]
    ifail
    Error flag (see diagnostics) [out]

Description

    The subroutine UF420 traces a magnetic field line segment passing through the geographic position mpos. The magnetic field line segment is limited by one of the following boundary conditions :
  • the altitude falt has to be reached;
  • the magnetic field intensity fbm(1) has to be reached.
  • The condition on the altitude can be avoided by setting falt to a value lower than -500.

    The different points along the field line segment are stored in the common block UC170. It includes the points corresponding to the boundary conditions, as well as, the points corresponding to the magnetic field intensities fbm(2), ..., fbm(nfbm). Note that the intensities set in the array fbm has to be strictely decreasing : fbm(1) > fbm(2) > fbm(nfbm).

History

    From version 1.13 to version 2.00, the algorithm has been improved for the case where the first boundary condition on the magnetic field intensity is close to the minimum value of the magnetic field intensity along the field line segment.

Diagnostics

    -42001, incorrect boundary conditions
    -42002 or -42004, strange behaviour of the field line near the altitude boundary condition
    -42003 or -42006, strange behaviour of B along the field line
    -42005, problem with the boundary condition on the altitude
    -42007, problem with the boundary conditions on B
    -42008 or -42010, find the minimum of B before any one of the boundary conditions
    -42009, too many points along the field line segment
    -42011, error in UF428 detected a posteriori

Common Blocks

    UC160, general constants
    UC170, temporary magnetic field line
    UC190, control parameters, set 1

Dependencies

Called by

    UL220, get information on a magnetic field line segment
    UF410, search the geographic position of a magnetic field line
    UF417, search the geographic position of a magnetic field line (new)
    UF411, search a local magnetic equator

Calls

    UF421, initialize and close a field line segment
    UF422, follow a field line until a boundary condition is reached
    UF424, search the lowest B value
    UF429, transpose a field line segment

See also

    FAQ G.05 Which are the coordinates and units used ?

Reported Bugs

    None

Examples

    G.06 How to start using the UNILIB library ?