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Define the parameters for the calculation of beam-beam
field.
BBFIELD
WX=WX=([,]),
[WXMAX=WXMAX=(,),]
R=r,
[NX=,] [NY=,]
[PSIZE=,] [NMOM=,]
;
- ,
- Horizontal width of the mesh in meters
for right and left-going beams.
If is not specified,
is adopted. No default for .
- ,
- If WXMAX is given, the with of
the mesh region
can vary in the range when the beam
fraction outside the range defined by WX
and R is significant. Note .
- r
- Aspect ratio ()/()
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
or or 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 . Default=1.
-
- For (x,y) points outside the mesh region,
a harmonic expansion using the elliptic coordinate
is used. The parameter specifies the
truncation of harmonics. takes only
the total charge term and ignores
the field outside. Default=10.
Note that the particles outside mesh region
receive the beam-beam kick unless ,
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