Beam Beam Kick

The beam beam kick requires a NODE_LAYOUT, say for example, ALS%t.

A beam-beam kick of type Beam_beam_node is given by:

  TYPE BEAM_BEAM_NODE
     REAL(DP), POINTER :: S
     REAL(DP), POINTER :: SX,SY,FK
     REAL(DP), POINTER :: XM,YM   ! trivial transverse displacement: not needed
     REAL(DP), POINTER :: BBK(:)  ! kick on closed orbit
     REAL(DP), POINTER :: A(:)    ! patch angles
     REAL(DP), POINTER :: D(:)    ! patch translation
     INTEGER, POINTER :: A_X1,A_X2 ! patch inverse propagator (Should not  be needed)
     LOGICAL(LP), POINTER :: PATCH ! true= patch
  END TYPE BEAM_BEAM_NODE

and is located on a node ``t'' as ``t%bb''. In PTC, if the beam is round (actually nearly round), the kick of the x-momentum is given by:

$$\Delta {p}_{x}= {(x-xm) fk \over {(x-xm)}^{2}+{(y-ym)}^{2}}\le... ...(y-ym)}^{2}}\right\} \over {\sigma }_{x}^{2}+{\sigma }_{x}^{2}}}\right)}\right)$$ (9.1)

This defines the variables, xm,ym,fk, ${\sigma}_x$ and ${\sigma}_y$.

The variables A(:) and B(:) as well as the discrete patches A_X1 and A_X2 must be set by the user to move the kick somewhere else. The logical PATCH is also needed if the patches are too be used.