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).