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GMAD implements almost all the standard MAD elements, but also allows to define arbitrary geometric entities and magnetic field configurations. The geometry description capabilities are extended by using “drivers” to other geometry description formats, which makes interfacing and standardisation easier. The syntax of a physical element declaration is
element_name : element_type, attributes;
for example
qd : quadrupole, l = 0.1*m, k1 = 0.01;
element_type
can be of basic type or inherited. Allowed basic types are
All elements except marker
, element
, ecol
, and rcol
are by default modeled with an inner cylindrical beampipe and an outer
cylindrical volume. (FOR MAD COMPATIBILITY sbend
SHOULD BE A TORUS).
The beampipe outer radius and thickness are defined by the
global beampipeRadius
and beampipeThickness
options; the beampipe outer radius can be redefined for almost every element
with the aper
option.
The beampipe material is defined by the global beampipeMaterial
option
(default: “Vacuum”), while the residual gas in the beampipe at the moment
cannot be changed by the user and is set to “Vacuum”.
The outer volume is represented (with the exception of the drift
element) by a cylinder with inner radius equal to the beampipe outer radius and
with outer radius given by default by the global boxSize
option, which
can usually be overridden with the “outR” option.
An already defined element can be used as a new element type. The child element will have the attributes of the parent.
q:quadrupole, l=1*m, k1=0.1; qq:q,k1=0.2;