The Tools menu provides tools for lattice studies.
| Close Lattice | Close the lattice. |
| Close Symmetric | Close the lattice symmetrically. |
| Track | Perform multiparticle tracking. |
| Trajectory | Plot a betatron motion trajectory into a graphical window. |
| Type Trajectory | Type a betatron motion trajectory into a text window. |
| Close Trajectory | Closes the closed orbit for circular machine. |
| Tune Diagram | Plots the tune diagram. |
| Show External File | Plots an external file. |
| Control | Controls behavior of Tools|Trajectory and Tools|Close Trajectory menus). |
Closes the lattice (finds a periodic solution for beta-functions and dispersions). The initial Twiss parameters in the main window are automatically updated, assuming that the periodic solution can be found.
Closes the lattice symmetrically i.e. force the alpha-functions and dispersion derivatives to be zero both at the lattice entrance and exit. If a solution can be found, the initial Twiss parameters in the main window are overwritten.
Performs multi-particle, multiturn tracking. Invoking Tools|Tracker menu opens a Tracker window. This window provides its own menu to control the tracking object behavior. Before tracking can be performed, general tracking parameters as well as an initial particle distribution must be specified.
To set the general tracking parameters, from the tracjing window menu invoke Setup|Parameters. The dialog allows one to specify the number of turns and the element index (the location) for the which tracking results will be reported. A negative or zero index implies the last element of the lattice. A checkbox determines whether the program should use a fast tracking algorithm (the default is the most accurate one) and whether Tracking results (normalized beam emittances, maximum particle coordinates, and survival fraction) are shown. The output window is fully editable: arbitrary text e.g. comments may be added.
Once general tracking parameters are set, the menu items Setup|Distribution and File|Read are enabled; either one may be invoked to specify an initial particle distribution. Use Setup|Distribution to generate a Gaussian particle in 6D phase space. The following parameters can be specified in the dialog window: RMAX, RMIN and the number of particles. RMAX and RMIN specify the inner and outer truncation radii in 6D phase space; particles with coordinates larger than RMAX*SIGMA or less than RMIN*SIGMA will be excluded. By setting RMAX close to RMIN, a spherical "shell" particle distribution in 6D space may be generated. The defaults are RMAX=6, RMIN=0. Other parameters for the transverse and longitudinal distributions (bunch length, energy spread and alpha) are prescribed in the 4D Beta-functions block and the space charge block (see Space Charge Menu). The 4D Beta-function block entries determine the transverse particle distribution, which is, in general, considered to be X-Y coupled (see 4D Beta-functions block and Input language description). If the 4D block does not exist, the program, after prompting the user, creates a template. The correct initial 4D Twiss functions and emittances must then be explicilty specified. Alternatively, one may use View 4D|Close 4D from the menu to automatically obtain periodic Twiss functions for a circular machine. Entries from the the space charge block are used to determine the equation of ellipse in longitudinal phase space (projection of 6D ellipsoid to the longitudinal plane): $$ \frac{\Delta p^2}{\sigma_p^2} - 2\tilde{\alpha} \frac{\Delta p \Delta s}{\sigma_p\sigma_s} + \frac{\Delta_s^2}{\sigma_s^2} = 1 - \tilde{\alpha^2} $$ where $\sigma_p$ and $\sigma_s$ are the energy spread and the bunch length (for definition of $\tilde{\alpha}$ see also Size4D). As it follows from the definition, the total longitudinal emittance is $$ \sqrt{1-\tilde{\alpha^2}} \sigma_p \sigma_s $$ If the initial dispersions in the 4D Beta-function block are not zero, an additional particle displacement proportional to its momentum deviation is assigned. If a special initial distribution is needed, the initial distribution can be read from a file by invoking File|Read from the Traker menu. The file format is as follows: The first line is the string "OptiM Track Data". Subsequent lines are (one line per particle) the 6 phase space coordinates: x[cm], dx/ds, y[cm], dy/ds, z[cm], Dp/p. The example below illustrates the required format:
OptiM Track Data -0.281148 -2.20735e-05 0.0973784 0.000123752 -0.0444716 0.000138878 .... -0.19935 4.71474e-05 -0.00284839 -8.62216e-05 0.199689 0.000104129
Two additional columns may be present. Column 7 is a particle ID. If none is assigned, it is automatically set to the particle index used internally. Column 8 is the statistical weight of the particle. If it is not assigned, it is set to 1.0
Once an initial particle distribution is established, tracking can be initiated. Upon completion, the initial and final phase space distributions are available from the Views menu. Any one of the X-Y, X-X', Y-Y', and S-dP/P projections may be selected. Plots of the normalized emittance, energy spread and beam intensity evolutions are available from the Plot menu. The initial and the final particle distributions may be saved by invoking File|Save from the Tracker menu.Plots betatron motion trajectory, i.e. plots a particle trajectory relative to the reference orbit. The program uses the initial particle positions angles and momentum deviation specified in the trajectory parameter block, whose format is shown below:
TrajParamBlock X[cm]=0. Teta_X[rad]=0. Y[cm]=0. Teta_Y[rad]=0. s[cm]=0. DeltaP/P=0. EndTrajParamBlock
If no trajectory parameter block is present, a template will automatically be created. The Tools|Control menu provides some control on how the trajectory is plotted.
Analogeous to Tools|Trajectory, but provides numerical output. The program prompts for initial betatron amplitudes and angles, and then propagates betatron trajectory along the lattice. Correctors kicks are accounted for. The Step parameter determines the spacing between samples. Each element is subdivided into a finite number of equal slices. The number of slices is selected to match the step parameter as closely as possible. A zero or negative step parameter causes the output to be produced only at the dowstream ends of elements. A filter allows one to include/exclude specific elements from the table (See Filtering). Output can also be limited to elements from a specified range. Setting the element indices for the start and end opf the range to zero implies that the entire lattice range is selected.
Determines the closed orbit for a ring where the closed orbit differs from the design orbit due to the presence of transverse and/or longitudinal correctors and momentum offset. This command updates the trajectory parameter block which is used by the Trajectory and Type trajectory commands. Tools|Control provides some control on how the trajectory closure is performed.
Plots a tune diagram. This is another type of graphical window but its functionality is similar to the general graphical window (see Graphical Window). A dialog allows the used to specify the extent of the tune space (where the tune diagram has to be build), the maximum order of resonances (for which resonance lines are shown) and the types of resonances (sum or coupling resonances).
Plots numerical values from an external text file. The file must be in tabular format. Any number of spaces and tabs delimits columns. Up to four curves can be shown simultaneously. The dialog box is self explanatory. One needs to assign: column for abscissa and ordinates and ordinate axis (left or right). If a column number is less than or equal to zero, the corresponding curve will not be shown.
Controls the behavior of Tools|Trajectory and Tools|Close Trajectory menus. The first two-way radio button allows one to choose how the orbit closure in a ring will be performed. If Use single plane closure for each plane is chosen, then only the entries of a 2-by-2 horizontal and vertical transfer matrices are used for closure; non-linear terms are ignored. In this case, the orbit can be excited by transverse correctors only (see K-transverse corrector). If Use general 6D closure is chosen, all non-linearities and plane-to-plane coupling are taken into account when the closed orbit is determined. In this case both transverse and longitudinal correctors, as well as electrostatic acceleration and RF cavities affect the beam motion. If no accelerating cavities are present in a ring, the longitudinal degree of freedom cannot be closed and one needs to check the 4D closure box. In this case only transverse coordinates are used for the closure and one additionally needs to write down a desired momentum offset in TrajParamBlock (see Trajectory). Three numeric parameters below Use general 6D closure button determine the iteration parameters for the 6D (or 4D) orbit closure. The second three-way radio button allows one to choose how the trajectory is plotted. If Normal plot is chosen then the vertical and horizontal beam displacements are plotted. If Plot beam displacement normalized by beam size is chosen then the program plots the beam displacements normalized by the beam sizes (x/Ax and y/Ay). And if Plot beam displacement together with beam boundaries is chosen the program, in addition to the beam centroids, plots the beam boundaries (x, x+Ax, x-Ax, and y, y+Ay, y-Ay). For the last two choices the beam size is computed the same way as for View| Sizes menu, i.e. the eighth check box of View|Control menu determines either the betatron beam size or the total beam size should be used.