10.9 BUMPER—A time-dependent kicker magnet with optional spatial dependence of the kick and no fringe effects. The waveform is in SDDS format, with time in seconds and amplitude normalized to 1. The optional spatial dependence is also specified as an SDDS file.

A time-dependent kicker magnet with optional spatial dependence of the kick and no fringe effects. The waveform is in SDDS format, with time in seconds and amplitude normalized to 1. The optional spatial dependence is also specified as an SDDS file.
Parallel capable? : yes
GPU capable? : no
Back-tracking capable? : no






Parameter Name UnitsType Default

Description






L M double 0.0

length






ANGLE RADdouble 0.0

kick angle






TILT RADdouble 0.0

rotation about longitudinal axis






DX M double 0.0

misalignment






DY M double 0.0

misalignment






DZ M double 0.0

misalignment






B2 1∕M2double 0.0

Sextupole term: By=Bo*(1+b2*xˆ
2  )






TIME_OFFSET S double 0.0

time offset of waveform






PERIODIC long 0

is waveform periodic?






PHASE_REFERENCE long 0

phase reference number (to link with other time-dependent elements)






FIRE_ON_PASS long 0

pass number to fire on






N_KICKS long 0

Number of kicks to use for simulation. 0 uses an exact result but ignores b2.






WAVEFORM STRINGNULL

<filename>=<x>+<y> form specification of input file giving kick factor vs time






DEFLECTION_MAP STRINGNULL

optional filename giving the spatial variation of the deflection






GROUP string NULL

Optionally used to assign an element to a group, with a user-defined name. Group names will appear in the parameter output file in the column ElementGroup






This element simulates a time-dependent kicker magnet as a rectangular dipole with no fringe field effects. To use this element, you must supply an SDDS file giving the time-dependent waveform. The element is called BUMPER to because HKICK, VKICK, KICKER are used for steering magnets.

The arrival time of the beam is taken to define the reference time, t = 0. Hence, if the waveform file has the maximum amplitude at t = 0, the beam will get kicked at the peak of the waveform. If the waveform peaks at t = tpeak, then setting TIME_OFFSET equal to -tpeak will ensure that the beam is kicked at the peak amplitude.

By default, the kicker fires on the first beam passage. However, if FIRE_ON_PASS is used, then the kicker is treated like a drift space until the specified pass. Note that the first pass is 0, not 1.

If PHASE_REFERENCE is non-zero, then the initial timing is taken from the first time-dependent element that has the same PHASE_REFERENCE value. This would allow, for example, simulating several kickers firing at the same time. Delays relative to this reference time can then be given with positive adjustments to TIME_OFFSET.

The waveform input file need not have equispaced points in time. However, the time values should increase monotonically.

The deflection map, if provided, should have four floating-point columns

  1. Transverse coordinates x and y, with units of m.
  2. Kick multipliers xpFactor and ypFactor, which are dimensionless quantities.

The resulting kick in each plane for a particle with coordinates (x,y,t,δ) is

               θA(t- t     )fq(x, y)
Δq ′(x,y,t,δ) = -------offset--------,
                      1 + δ
(34)

where q stands for x or y, θ is the specfied deflection angle, A(t) is the time-dependent amplitude waveform, and fq(x,y) is the deflection map factor for the q plane at the particle’s location.

The data in the deflection map file must be sorted so that x changes fastest, which can be accomplished using the command

sddssort input.sdds -column=y,incr -column=x,incr

This element simulates a dipole kicker only. For multipole kickers, see the MBUMPER element.

Explanation of <filename>=<x>+<y> format: Several elements in elegant make use of data from external files to provide input waveforms. The external files are SDDS files, which may have many columns. In order to provide a convenient way to specify both the filename and the columns to use, we frequently employ <filename>=<x>+<y> format for the parameter value. For example, if the parameter value is waveform.sdds=t+A, then it means that columns t and A will be taken from file waveform.sdds. The first column is always the independent variable (e.g., time, position, or frequency), while the second column is the dependent quantity.

CCBEND