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A simulation of a beam-driven TM monopole mode of an RF cavity.
Parallel capable? : yes
Parameter Name Units Type Default Description
RA $Ohm$ double 0.0 shunt impedance
RS $Ohm$ double 0.0 shunt impedance (Ra=2*Rs)
Q   double 0.0 cavity Q
FREQ $Hz$ double 0.0 frequency
CHARGE $C$ double 0.0 beam charge (or use CHARGE element)
INITIAL_V $V$ double 0.0 initial voltage
INITIAL_PHASE $RAD$ double 0.0 initial phase
INITIAL_T $S$ double 0.0 time at which INITIAL_V and INITIAL_PHASE held
BETA   double 0.0 normalized load impedance
BIN_SIZE $S$ double 0.0 bin size for current histogram (use 0 for autosize)
N_BINS   long 20 number of bins for current histogram
PRELOAD   long 0 preload cavity with steady-state field
PRELOAD_FACTOR   double 1 multiply preloaded field by this value
RIGID_UNTIL_PASS   long 0 don't affect the beam until this pass
DETUNED_UNTIL_PASS   long 0 cavity is completely detuned until this pass
SAMPLE_INTERVAL   long 1 passes between output to RECORD file
RECORD   STRING NULL output file for cavity fields
SINGLE_PASS   long 0 if nonzero, don't accumulate field from pass to pass
PASS_INTERVAL   long 1 interval in passes at which to apply PASS_INTERVAL times the field (may increase speed)
FREQ_WAVEFORM   STRING NULL $<$filename$>$=$<$x$>$+$<$y$>$ form specification of input file giving frequency/f0 vs time, where f0 is the frequency given with the FREQ parameter

A simulation of a beam-driven TM monopole mode of an RF cavity.
Parameter Name Units Type Default Description
Q_WAVEFORM   STRING NULL $<$filename$>$=$<$x$>$+$<$y$>$ form specification of input file giving qualityFactor/Q0 vs time, where Q0 is the quality factor given the the Q parameter.
RAMP_PASSES   long 0 Number of passes over which to linearly ramp up the impedance to full strength.
BINLESS   long 0 If nonzero, use algorithm that doesn't requiring binning. Best for few particles, widely spaced.
RESET_FOR_EACH_STEP   long 1 If nonzero, voltage and phase are reset for each simulation step.
LONG_RANGE_ONLY   long 0 If nonzero, induced voltage from present turn does not affect bunch. Short range wake should be included via WAKE or ZLONGIT element.
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 beam-driven monopole mode cavity using the fundamental theorem of beam loading and phasor rotation.

Normally, the field dumped in the cavity by one particle affects trailing particles in the same turn. However, if one is also using a WAKE or ZLONGIT element to simulate the short-range wake of the cavity, this would be double-counting. In that case, one can use LONG_RANGE_ONLY=1 to suppress the same-turn effects of the RFMODE 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.

next up previous
Next: RFTM110 Up: Element Dictionary Previous: RFDF
Robert Soliday 2014-06-26