3.8 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.

• 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.