Status of lattice studies 30-June-2002

7-pole wiggler lattice -

The 14 wiggler linear lattice is designed using taylor tracking and matrix calculation based on the fit dlr0208.in to the vector fields data /cdat/cesr38/disk1/critten/w7-20_22_fid.table. The name of the lattice file is /cdat/cesr38/disk1/dlr/bmad_devel/dynamic_aperture/bmad_20_22_dlr0208_taylor_v3.lat This is a preliminary optimization. The following are not quite right:

  • Pretzel amplitude is only 15mm. The nominal design amplitude is 18mm
  • Dispersion at IP is not zero and alpha* is not quite zero.
  • There is no constraint on emittance in the optimization. Software had not yet been developed to compute emittance with the wiggler model.
  • The sextupoles give chromaticitiy near zero but have not been optimized.
  • Details of the linear lattice parameters are summarized here
  • Note that whereas the lattice is designed using taylor mapping throught the wigglers, the dynamic aperture is computed by runge kutta tracking through the tabulated fields. Linear optical parameters may be distorted in the conversion. 7-pole wiggler dynamic aperture For the dynamic aperture tracking the taylor tracking method is replaced with runge kutta integration through the vector fields table /cdat/cesr38/disk1/critten/w7-20_22_fid.table The choice of tunes is based on a tune scan with Q_z = -0.109. (V_rf = 10MV) The curves with points indicate the maximum starting amplitude that survives 1000 turns. Particles with amplitude outside the physical aperture of the machine are considered lost. The dashed lines indicate the maximum starting amplitude that survives 20 turns and roughly correspond to the linear/physical aperture. Kickers are added to the lattice at either end of the wigglers and tuned so that the closed orbit is flat with separators off. The pretzel is on of course for the tracking. The solid line indicates 10 sigma_x with horizontal emittance = 0.2mm-mrad and vertical emittance = 0.1mm-mrad

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    8-pole wiggler lattice -

    The 14 wiggler linear lattice is designed using taylor tracking and matrix calculation based on the fit dlr0310.in to the vector fields data /cdat/cesr38/disk1/critten/w8-20_10_fid.table. The name of the lattice file is /cdat/cesr38/disk1/dlr/bmad_devel/dynamic_aperture/bmad_8pole_taylor_v3.lat This is a preliminary optimization. The following are not quite right:

  • Crossing angle is 3.4mrad. That seems too big
  • The pretzel ampltitude is east-west asymmetric
  • Dispersion at IP is not zero and alpha* is not quite zero.
  • There is no constraint on emittance in the optimization. Software had not yet been developed to compute emittance with the wiggler model.
  • The sextupoles give chromaticitiy near zero but have not been optimized. The sextupoles are the same as for the 7 pole lattice.
  • Details of the linear lattice parameters are summarized here
  • Note that whereas the lattice is designed using taylor mapping throught the wigglers, the dynamic aperture is computed by runge kutta tracking through the tabulated fields. Linear optical parameters may be distorted in the conversion.

    8-pole wiggler dynamic aperture

    For the dynamic aperture tracking the taylor tracking method is replaced with runge kutta integration through the vector fields table /cdat/cesr38/disk1/critten/w8-20_10_fid.table The choice of tunes is based on a tune scan with Q_z = -0.109. (V_rf = 10MV) We use the same tunes as for the 7 pole tracking. The curves with points indicate the maximum starting amplitude that survives 1000 turns. Particles with amplitude outside the physical aperture of the machine are considered lost. The dashed lines indicate the maximum starting amplitude that survives 20 turns and roughly correspond to the linear/physical aperture. The closed orbit with separators off is flat. No compensating kickers are required. The pretzel is on of course for the tracking.

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    7-pole 17kg wiggler dynamic aperture 15-August-2002

    Optimize da by first running sextz and then bmadz including 4X4det in figure of merit. Replace standard disp.dat with disp_easy.dat. Otherwise off energy unstable.
  • bmad_7pole_17kg_0423_v4_c.lat
  • Details
  • DA postscript
  • Constraint files in ~dlr/bmad_devel/7pole_17

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    Underway - 1-July-2002

    In order to remove some of the vagaries of the comparison of 7pole and 8pole optics we are: -------------------------------------------------

    8pole 21kg lattice - 17-september-2002

    Based on the study of the phase space derived from runge kutta integration through the vector fields table, as compared to the symplectic integration based on the fit to the field table, and also remarks about runge kutta vs borsi integration, the symplectic integration is likely a better representation of dynamic aperture. The lattice bmad_8pole_21kg_v2_s3.lat and sextupoles are optimized (BMADZ) with symplectic integration through the 8 pole wiggler. The terms of the fitted function are in critten/w8-20_20_161_0621_009500.in The fit is to critten/w8-20_20_161_fid.table. Details of the lattice are here. The dynamic aperture ((PS) is determined by symplectic integration through the wigglers.