
Undulator Parameters
AW0
The normalized, dimensionless rms undulator parameter, defined by AW0 = (e/mc)(B_{u}/k_{u}), where e is the electron charge, m is electron mass, c is speed of light, k_{u}=2/_{u} is the undulator wave number, _{u} is the undulator period. B_{u} is the rms undulator field with B_{u} = B_{p}/2 for a planar undulator and B_{u} = B_{p} for a helical undulator, where B_{p} is the onaxis peak field.
IWITYP
Flag indicating the undulator type. A value of zero indicates a planar undulator, any other value a helical one.
FBESS0
The coupling factor of the electron beam to the radiation field due to the longitudinal wiggle motion of the electrons. It is 1.0 for a helical undulator and J_{0}(x)  J_{1}(x) for a planar undulator where J_{0}(x), J_{1}(x) are Bessel functions and x = AW0^{2}/2(1+AW0^{2}). If FBESS0 is set to 0.0 GENESIS 1.3 calculates the value.
NSEC
The number of sections of the undulator. Note that a section length in not automatically identical with the undulator module length. GENESIS 1.3 aligns modules to the FODOlattice. If a module ends within a FODO cell the next module starts with the beginning of the next cell. Sometimes this results in a longitudinal gap between adjacent undulator modules.
AWD
A virtual undulator parameter for the gap between undulator modules. The only purpose of this parameter is to delay the longitudinal motion of the electrons in the same manner as AW0 does within the undulator modules. It is used to keep the electron and radiation phases synchronize up to the point when the interaction at the next undulator module starts again. AWD has typically the same value as AW0, but might vary for optimum matching between the modules.
WCOEFZ(1)
Start of undulator tapering. Note that tapering is applied, even the magnetic lattice is defined by an external file.
WCOEFZ(2)
The relative change of the undulator field over the entire taper length (AW(exit) = (1  WCOEFZ(2)) AW(entrance)). In the case of a multi section undulator GENESIS 1.3 tapers the magnetic field over the gaps as well, resulting in a jump of the magnetic field AW(z) between two modules.
WCOEFZ(3)
The taper model: = 1 for linear taper, = 2 for quadratic taper, or no taper otherwise.
IERTYP
Type of undulator field errors. Either a uniform (+/1) or Gaussian (+/ 2) distribution can be chosen. If IERTYP is negative the errors are correlated to minimize the first and second field integral. IERTYP =0 disables field errors. Field errors requires a integration step size of half an undulator period (DELZ = 0.5). Note that field errors are applied even if the magnetic lattice is defined by an external file.
DELAW
RMS value of the undulator field error distribution. A value of zero disables field errors.
AWX
Maximum offset in x for undulator module misalignment. The error for each individual module follows a uniform distribution
AWY
Maximum offset in y for undulator module misalignment. The error for each individual module follows a uniform distribution 