| Parameter Description | Argument Order | Argument Name | Units | Default Value |
|---|---|---|---|---|
| Total Length | 1 | cm | ||
| No of cells | 2 | |||
| Effective length | 3 | Eff_L | cm | |
| Voltage | 4 | A | MV | 0.0 |
| Phase | 5 | phase | deg | 0.0 |
| Wavelength | 6 | WaveL | cm | 0.0 |
The letters "A" and "a" denote an accelerating cavity. The first parameter is the total length of the cavity in cm. The second parameter is the number of cells. The third parameter is the effective length of the cell. The fourth parameter is the total accelerating voltage of the cavity for on-crest acceleration. The fifth parameter is the accelerating phase relative to the phase of the on-crest acceleration; a positive phase implies that a particle goes through the cavity after the voltage reaches its maximum. the sixth parameter (WaveL) is the wavelength of the accelerating voltage in vacuum $(\lambda = c/f)$. The program calculates focusing effect of the cavity fields in the second order of the perturbation theory for the case when each cell is approximated by the pill-box cavity with length equal to Eff_L. This approximation works well for relativistic particles if the energy change in one cell is much less than the current particle energy. When that is not the case, one needs to use W-general RF cavity. Note that by definition the determinant of the cavity transfer matrix is equal to 1 (see Linear optics calculations-general RF cavity).
Example: # cavity with total length of 50 cm and accelerating gradient of 2.5 MeV. The cavity consists of 5 # cells with the cell effective length of 7 cm. Accelerating phase is equal to zero (on crest # acceleration) A2 L[cm]=50 Ncell=5 Eff_L[cm]=7 A[MeV]=2.5 Phase[deg]=0 WaveL[cm]=20