&CELL: methods

potential_function

Garfield classifies chambers according to the number and orientation of planes, the presence of periodicities and the location of the wires as one of the following types:

Potential	Use
A	Non-periodic cells with at most 1 x- and 1 y-plane
B1X	x-Periodic cells without x-planes and at most 1 y-plane
B1Y	y-Periodic cells without y-planes and at most 1 x-plane
B2X	Cells with 2 x-planes and at at most 1 y-plane
B2Y	Cells with 2 y-planes and at at most 1 x-plane
C1	Doubly periodic cells without planes
C2X	Doubly periodic cells with x-planes
C2Y	Doubly periodic cells with y-planes
C3	Doubly periodic cells with x- and y-planes
D1	Round tubes without axial periodicity
D2	Round tubes with axial periodicity
D3	Polygonal tubes without axial periodicity
D4	Polygonal tubes with axial periodicity
BEM	Field calculated by neBEM
MAP	Finite element field maps

Each chamber type has its own potential function. For numerical purposes, nearly all potential functions are further subdivided into a set of domains according to the aspect ratio of the periodicities, the distance between wires and planes etc.

Versions of most potential functions exist which take advantage of vector hardware. The choice between scalar and vector versions is made a compilation time.

Use GET_CELL_DATA to find out which potential function is in use. The cell type is also displayed when the CELL-PRINT option is active and in response to the PRINT-CELL command.

Garfield has shape functions to deal with various element types such as straight triangles, curved triangles, straight tetrahedra, curved tetrahedra, hexahedra etc. Use CELL-PRINT as described above to find the shape functions used for the current chamber.

neBEM has a range of Green's functions too: line elements, right-angled triangles and rectangles. Most models contain several of these elements at the same time.

coordinate_system

Cells are described using one of the following 3 coordinate systems:

Coordinate system	Use
Cartesian	Cells described in (x,y) coordinates, field maps
Polar	Cells described in (r,\φ) coordinates
Tube	Cells which contain a TUBE

One can use the GET_CELL_DATA to find out which system is in use.

Additional information on:

Cartesian	Polar
Tube

shape_function

For information on shape functions, see:

A. R. Mitchel and R. Wait, The finite element method in partial differential equations, Wiley (1977), in particular pp 108-110.

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Formatted on 21/01/18 at 16:55.