randomizeBunchCurrent

• type: Setup command.
• function: The command defines the randomization parameters for the bunch pattern. The randomization is performed on the ideal bunch pattern before each growth rate calculation. If a sweep of frequency is requested (sweepFrequency), then a new random bunch pattern is generated for each HOM frequency value. If a HOM-frequency Monte Carlo simulation is requested (randomizeHOMFrequencies), then a new random bunch pattern is generated for each HOM frequency sample. Thus there are two random components in the resulting growth rate distribution: HOM frequency and bunch population.

&randomizeBunchCurrent struct
    long seed = -987654323;
    long uniform = 1;
    double absoluteSpreadMA = 0;
    double relativeSpread = 0;
&end.

• seed -- A large negative number for the random number generator. This will use an independent generator from the HOM frequency.
• uniform -- Flag for uniform distribution. Presently only uniform distribution is available.
• absoluteSpreadMA -- Spread in bunch distribution in units of mA. This is useful in top-up mode injection where the total current is constant but individual bunches have spread equal to the charge per injection bunch. For example if a bunch pattern has 4 mA per bunch and the spread is 1 mA, then some bunches may have current as low as 3.5 mA and others as high as 4.5 mA.
• relativeSpread -- Spread in bunch distribution in fraction.

subsectionsweepFrequency

• type: Setup command
• function: Sets up a sweep of the resonator frequency value of a selected HOM. The setup takes effect only when an action command is executed.

&sweepHOMFrequency
    long resonatorNumber = 0
    double frequencyRange = 0.0
    long points = 100
    STRING filename = NULL
&end

• resonatorNumber -- HOM resonator number to be swept in frequency. The numbering starts at 0, and proceed in the order that the resonators were read in the HOM definition file or files.
• frequencyRange -- Sweep range in Hz. The range starts at the unperturbed HOM resonator frequency minus frequencyRangeHz and ends at the unperturbed HOM resonator frequency plus frequencyRangeHz. If frequencyRangeHz is set to 0 or not specified, then frequencyRangeHz=$f_0$ where $f_0$ is the revolution frequency.
• points -- Number of points in the sweep.
• filename -- SDDS file in which the results are written. The columns are the swept HOM frequency, the maximum growth rate, and the frequency shift of the fastest growing CBM. Recommended naming conventions: <something>.CBMFreq