HOM Definition SDDS File Format

The allowed column names for the HOM definition file are:

`Frequency`or`f`-- Required column. Frequency in units of Hz or MHz. The program internally converts to Hz.`ShuntImpedance`or`R`or`Rs`or`Rt`-- Required column (see above). Shunt impedance in units of Ohm for monopole HOMs, and units of Ohm/m for dipole HOMs.`Q`or`QualityFactor`-- Required column (see above). Quality factor of the resonator.`ROverQ`or`R/Q`or`ROQ`-- Required column (see above). Shunt impedance divided by . In units of Ohm for monopole HOMs, and units of Ohm/m for dipole HOMs.`DeQFactor`or`deQFactor`-- Factor by which to reduce the of the HOM after reading in this file.`StaggeringStep`or`staggeringStep`or`DeltaFrequency`or`deltaFrequency`or`df`-- Optional column. Units of Hz only. Default value is 0. If larger than one, then the frequencies of the`NumberOfCavities`HOM resonators are staggered by this interval.`ShiftToResonance`-- Optional column. Default value is 0. If non-zero, then the frequency of the HOMs is shifted to the closest resonance. If`staggeringStep`is non-zero, then the frequency shifting is done after staggering the frequencies.`NumberOfCavities`or`NCavities`or`Cavities`or`cavities`-- Optional parameter. Default value is 1. If 0, then this HOM type is not used in the calculation. If greater than one, then the HOM resonator is duplicated`numberOfCavities`times.

Here is an example of an `SDDS` HOM definition file for the APS ring cavities:

SDDS1 &description text="APS cavity longitudinal HOMs" contents="HOM definition" &end &column name=Frequency, symbol=f, units=Hz, type=double, description="Resonant frequency of HOM resonator" &end &column name=ShuntImpedance, symbol=R, units=Ohm, type=double, description="Shunt impedance of longitudinal HOM resonator" &end &column name=Q, symbol=Q, units="", type=double, description="Q of longitudinal HOM resonator" &end &column name=NumberOfCavities, symbol=N$bcav$n, units="", type=long, description="Number of cavities for each HOM" &end &column name=StaggeringStep, units=Hz, type=double, description="Staggering frequency steps between cavity HOMs" &end &column name=ShiftToResonance, type=long, description="flag causes automatic shift to resonance after Staggering" &end &data mode=ascii, noRowCounts=1 &end 558.7e6 13.6e6 68e3 16 -0.08e6 0 761.1e6 25.6e6 53e3 16 -0.7e6 0 962.0e6 6.1e6 54e3 16 -1.2e6 0 1017.4e6 2.6e6 41e3 16 -1.7e6 0 1145.1e6 2.7e6 92e3 16 -1.5e6 0 1219.2e6 3.6e6 41e3 16 -1.9e6 0