linear_chromatic_tracking_setup

• type: setup command.
• function: define chromatic variation of beta functions, tunes, etc. for using in fast linear-chromatic tracking

&linear_chromatic_tracking_setup
    double nux[4] = {-1, 0, 0, 0};
    double betax[2] = {1.0, 0.0};
    double alphax[2] = {0.0, 0.0};
    double etax[2] = {0.0, 0.0};
    double etapx[2] = {0.0, 0.0};
    double nuy[4] = {-1, 0, 0, 0};
    double betay[2] = {1.0, 0.0};
    double alphay[2] = {0.0, 0.0};
    double etay[2] = {0.0, 0.0};
    double etapy[2] = {0.0, 0.0};
    double alphac[2] = {0.0, 0.0};
&end

• nux -- Provide the horizontal tune plus its first three chromatic derivatives, i.e., $\partial \nu_x/\partial\delta$, $\partial^2 \nu_x/\partial\delta^2$, and $\partial^3 \nu_x/\partial\delta^3$.
• betax -- Provide the horizontal beta function plus its chromatic derivative.
• alphax -- Provide the horizontal alpha function plus its chromatic derivative.
• etax -- Provide the first- and second-order horizontal dispersion: $\eta_x = \eta_x\left[0\right] + \eta_x\left[1\right]\delta$.
• etapx -- Provide the first- and second-order horizontal dispersion slope.
• alphac -- Provide the first and second-order momentum compaction. N.B: if you are tracking with an rf cavity, be sure that your lattice length equal to the actual circumference. See the example below.

An example of a good lattice for use with this feature is the following:

! Actual length of the ring
d0: drift,l=30.6667
! Actual rf voltage and frequency
rf: rfca,l=0,volt=30e3,phase=180,freq="c_mks 30.6667 /"
w1: watch,filename="%s.w1",mode="centroid"
ring: line=(d0,rf,w1)

Any additional elements (e.g,. wakes or impedances) should follow d0. No other elements represented by a matrix should be present!