Post on 05-Jan-2016
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UPDATE IN PTC-ORBIT PSB STUDIES Space charge meeting (27-04-2012) *
Vincenzo Forte
*Follows LIS meeting presentation 16/04/2012
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
Logical path*Lattice setup
Inject starting 6-D matched distribution
PTC ORBIT basic settings
RMS emittance tunes
Adding of space charge Orbit routines
1000 turns tracking
95-99% emittance
Results analysis
Best settings choose
Externally created (MadX, …)Internally modified (tables)
Externally created (Mathematica, …)
PTC-ORBIT
Plots and tunes footprints
*From LIS m
eeting presentation 16/04/2012
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
Results – first without space charge…*y
*From LIS m
eeting presentation 16/04/2012
Why this transitory without space charge???
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
D.O.E.*Lattice setup
Inject starting 6-D matched distribution
PTC ORBIT basic settings
ax bx ay by Dx Dpx
Lattice (PTC) 0.8762e-5 5.5940 -0.22351e-3 3.6225 -1.3340 0.13270e-3
250e3 (Matlab post p.) 1.0819e-4 5.5890 0.0022 3.6187 -1.3372 -9.4e-4
500e3 (Matlab post.p.) -3.0357e-4 5.5903 -4.7075e-4 3.6186 -1.3440 7.8642e-4
1000e3 (Matlab post p.) -0.0023 5.5901 * -1.81e-5 3.6219 * -1.3418 6.5791e-4
* Beta functions statistical precision increases with number of m.p.
*From LIS m
eeting presentation 16/04/2012
The initial distributions, as usual, were matched to this initial parameters from PTC Twiss table output
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
• In the PSB study the introduction of time-dependent elements is useful to control some lattice’s elements during the simulations.
This is obtained in PTC-Orbit through tables, that let us vary the waveform of magnets strengths and RF cavities to desired functions (like ramps or even non-linear) through linear interpolations in time. In the PSB the (LHC) beam will be injected horizontally into each PSB ring with a chicane using four dipole magnets (BS), and a painting bump using four kicker magnets (KSW). Then, we have also a double harmonic RF system that can be managed through tables (i.e. for acceleration).
• Regarding to our preliminary lattice (bumps at 0, kickers at 0, double harmonic without acceleration), we initially took a complete lattice (with bumps, kickers at non-0 value) and then applied tables to overwrite (at 0 value) the BS and KSW strengths and to define the RF cavity.
Preliminary considerations
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
*From LIS m
eeting presentation 16/04/2012
fractional tunes 0.277351800735185 0.431269833678875 name s betax betay alphax alphay eta_x etap_x PSBRING$START 0.0000 5.5940 3.6225 0.87260E-05 -0.22351E-03 -2.5655 0.25532E-03
ax bx ay by Dx Dpx
Lattice (PTC) 0.8762e-5 5.5940 -0.22351e-3 3.6225 -1.3340 0.13270e-3
250e3(Matlab post p.) 1.0819e-4 5.5890 0.0022 3.6187 -1.3372 -9.4e-4
500e3 (Matlab post.p.) -3.0357e-4 5.5903 -4.7075e-4 3.6186 -1.3440 7.8642e-4
1000e3(Matlab post p.) -0.0023 5.5901 * -1.81e-5 3.6219 * -1.3418 6.5791e-4
The initial distributions, as usual, were matched to this initial parameters from PTC Twiss table output
These dispersions values must be multiplied for brel ~ 0.52
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
And so… what generated the inital oscillations if the Twiss are matched?
• We made an attempt… what if it was just a mismatching?
After 1000 turns, but even much before, the distribution seems to be matched
At the beginning there seems to be a mismatching in vertical transverse plane
Attempt: We took the distribution at turn 1000 and made a new run for 50 turns with this one as initial distribution
y
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
And so… what generated the inital oscillations if the Twiss are matched?
Now it’s vertically matched … but w.r.t. which Twiss parameters ???ax bx ay by Dx Dpx
Lattice (Twiss PTC) 0.8762e-5 5.5940 -0.22351e-3 3.6225 -1.3340 0.13270e-3
1000e3 (init. unmatched) -0.0023 5.5901 -1.81e-5 3.6219 -1.3418 6.5791e-4
1000e3 (finally matched) 5.7977e-5 5.6277 4.8118e-4 3.2210 -1.3443 -1.715e-4
So… why are the values different from the PTC Twiss table ones??
Preliminary results of the PTC/ORBIT convergence studies in the PSB - Vincenzo Forte
InitPTC("PSB_PTC_ORBIT_FLAT_427_443.TXT");
ReadPTCscript("fringe.ptc");ReadPTCscript("chrom.ptc");
///////////////////////////////////////////////////////////// (2) PTC scripts for tracking WITH time-dependent elements ///////////////////////////////////////////////////////////
ReadPTCscript("PSB_PTC_TOTAL_RAMP_RFTable.ptc");
ReadPTCscript("twiss_script.ptc");
….
Tracking routines
ReadPTCscript("twiss_script.ptc");
Diagnostic routines
fractional tunes 0.276163580722948 0.416531295482894 name s betax betay alphax alphay eta_x etap_xPSBRING$START 0.0000 5.6285 3.2533 -0.23633E-14 0.31041E-14 -2.5877 0.16376E-14
W. Point tunes will be consequently modified too after applying tables
It depends on the position where you put the ReadPTCscript("twiss_script.ptc") command:
• If you put before tracking routines you are still considering the complete lattice with bumps and kickers (at non-zero value)
• If you put after (or during) tracking loops, the tables will be effectively applied and the lattice will change (bumps and kickers at 0).