|Q||double||0.0||cavity Q (for cavity that charges up to given voltage from 0)|
||phase reference number (to link with other time-dependent elements)|
||does cavity change central momentum?|
||set to 1 for long runs to avoid rounding error in phase|
|FIDUCIAL||STRING||NULL||mode for determining fiducial arrival time (light, tmean, first, pmaximum)|
||include focusing at entrance?|
||include focusing at exit?|
|BODY_FOCUS_MODEL||STRING||NULL||None (default) or SRS (simplified Rosenzweig/Serafini for standing wave)|
||Number of kicks to use for kick method. Set to zero for matrix method.|
|T_REFERENCE||double||-1||arrival time of reference particle|
||Linearize phase dependence?|
||Lock phase to given value regardless of bunch centroid motion?|
|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|
The phase convention is as follows, assuming a positive rf voltage:
PHASE=90 is the crest for acceleration.
PHASE=180 is the stable
phase for a storage ring above transition without energy losses.
The body-focusing model is based on Rosenzweig and Serafini, Phys. Rev. E 49 (2), 1599. As suggested by N. Towne (NSLS), I simplified this to assume a pure pi-mode standing wave.
CHANGE_T parameter may be needed for reasons that stem from
elegant's internal use of the total time-of-flight as the
longitudinal coordinate. If the accelerator is very long or a large
number of turns are being tracked, rounding error may affect the
simulation, introducing spurious phase jumps. By setting
CHANGE_T=1, you can force elegant to modify the time
coordinates of the particles to subtract off , where
is the rf period and
you are tracking a ring with rf at some harmonic of the revolution
frequency, this will result in the time coordinates being relative to
the ideal revolution period, . If you have multiple rf
cavities in a ring, you need only use this feature on one of them.
Also, you can use
CHANGE_T=1 if you simply prefer to have the
offset time coordinates in output files and analysis.
N.B.: Do not use
CHANGE_T=1 if you have rf cavities that
are not at harmonics of one another or if you have other
time-dependent elements that are not resonant.