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twiss_output

&twiss_output
    STRING filename = NULL;
    long matched = 1;
    long output_at_each_step = 0;
    long output_before_tune_correction = 0;
    long final_values_only = 0;
    long statistics = 0;
    long radiation_integrals = 0;
    long concat_order = 3;
    long higher_order_chromaticity = 0;
    long higher_order_chromaticity_points = 5;
    double higher_order_chromaticity_range = 4e-4;
    double chromatic_tune_spread_half_range = 0;
    long quick_higher_order_chromaticity = 0;
    double beta_x = 1;
    double alpha_x = 0;
    double eta_x = 0;
    double etap_x = 0;
    double beta_y = 1;
    double alpha_y = 0;
    double eta_y = 0;
    double etap_y = 0;
    STRING reference_file = NULL;
    STRING reference_element = NULL;
    long reference_element_occurrence = 0;
    long reflect_reference_values = 0;
    long cavities_are_drifts_if_matched = 1;
    long compute_driving_terms = 0;
    long leading_order_driving_terms_only = 0;
    long local_dispersion = 1;
&end

The output file from this command contains the following columns, giving values of quantities at the exit of each element, unless otherwise noted.

The output file contains the following parameters. Note that chromatic quantities depend on the order settings of the individual elements, the default order (in run_setup), and the concatenation order given in the twiss_output command. These quantities pertain to the end of the lattice or to the lattice as a whole.

N.B.: the higher-order dispersion and higher-order chromaticity are computed using the concatenated third-order matrix. However, elegant only has third-order matrices for three elements: alpha magnets, quadrupoles, and sextupoles. This may be acceptable if any dipoles (for example) have large bending radius. Users who are concerned about these effects should perform off-energy tracking using canonical elements (i.e., CSBEND, KQUAD, KSEXT, and MULT), which include energy dependence to all orders.

Also, note that by default all elements are computed to second order only. You must change the default\_order parameter on run\_setup to 3 in order to use the third-order matrices for alpha magnets, quadrupoles, and sextupoles. You may also use the ORDER parameter on individual element definitions.


Table 2: Meaning of the various driving terms[29].
Term Name Explanation
h11001 drives x chromaticity
h00111 drives y chromaticity
h20001 drives synchro-betatron resonances
h00201 drives momentum-dependence of beta functions
h10002 drives second order dispersion
h21000 drives $\nu_x$
h30000 drives $3 \nu_x$
h10110 drives $\nu_x$
h10020 drives $\nu_x - 2 \nu_y$
h10200 drives $\nu_x + 2 \nu_y$
h22000 drives $d\nu_x/dJ_x$
h11110 drives $d\nu_x/dJ_y$
h00220 drives $d\nu_y/dJ_y$
h31000 drives $2 \nu_x$
h40000 drives $4 \nu_x$
h20110 drives $2 \nu_x$
h11200 drives $2 \nu_y$
h20020 drives $2 \nu_x - 2 \nu_y$
h20200 drives $2 \nu_x + 2 \nu_y$
h00310 drives $2 \nu_y$
h00400 drives $4 \nu_y$


next up previous
Next: track Up: Namelist Command Dictionary Previous: twiss_analysis
Robert Soliday 2014-06-26