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  Define the parameters for the calculation of beam-beam field.  BBFIELD WX=tex2html_wrap_inline8016tex2html_wrap_inline7312WX=(tex2html_wrap_inline8016[,tex2html_wrap_inline8022]), [WXMAX=tex2html_wrap_inline8026tex2html_wrap_inline7312WXMAX=(tex2html_wrap_inline8026,tex2html_wrap_inline8032),] R=r, [NX=tex2html_wrap_inline7402,] [NY=tex2html_wrap_inline7404,] [PSIZE=tex2html_wrap_inline8048,] [NMOM=tex2html_wrap_inline8052,] ;
Horizontal width of the mesh in meters for right and left-going beams. If tex2html_wrap_inline8022 is not specified, tex2html_wrap_inline8060 is adopted. No default for tex2html_wrap_inline8016.
If WXMAX is given, the with of the mesh region can vary in the range tex2html_wrap_inline8068 when the beam fraction outside the range defined by WX and R is significant. Note tex2html_wrap_inline8070.
Aspect ratio (tex2html_wrap_inline8074)/(tex2html_wrap_inline8076) of the horizontal to vertical mesh size. This is common to right and left-going beams. No default.
Number of horizontal and vertical bins. Present version uses Fast Fourier Transformation so that a power of 2 is the best choice. Other numbers are also allowed but those of the form tex2html_wrap_inline8082 or tex2html_wrap_inline8084 or tex2html_wrap_inline8086 are recommended. Default=32.
Macro-particle size in units of the bin size. Macro-particles are treated as a rectangular of uniform distribution. Must be tex2html_wrap_inline8090. Default=1.
For (x,y) points outside the mesh region, a harmonic expansion using the elliptic coordinate is used. The parameter tex2html_wrap_inline8052 specifies the truncation of harmonics. tex2html_wrap_inline8098 takes only the total charge term and tex2html_wrap_inline8100 ignores the field outside. Default=10.
Note that the particles outside mesh region receive the beam-beam kick unless tex2html_wrap_inline8100, but the field created by them is not taken into account. See Sec.5.6 for more detail.

Note that the longitudinal mesh size,  which is common to beam-beam field and luminosity calculations, has to be defined by the parameter Smesh  by the SET command. Its value at the time when PUSH started is used thoughout the PUSH loop.

Toshiaki Tauchi
Thu Dec 3 17:27:26 JST 1998