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Jim Crittenden Cornell Laboratory for Accelerator-Based Sciences and Education

Space Charge Electric-Field Calculations for Coherent Tune Shift Estimations using the Electron-cloud Modelling Algorithm ECLOUD. Jim Crittenden Cornell Laboratory for Accelerator-Based Sciences and Education Electron Cloud Simulations Meeting Wilson Lab 14 January 2009.

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Jim Crittenden Cornell Laboratory for Accelerator-Based Sciences and Education

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  1. Space Charge Electric-Field Calculations for Coherent Tune Shift Estimationsusing the Electron-cloud Modelling Algorithm ECLOUD Jim Crittenden Cornell Laboratory for Accelerator-Based Sciences and Education Electron Cloud Simulations Meeting Wilson Lab 14 January 2009

  2. Overview of Modelling Parameters and Data Sets CesrTA Electron Cloud Simulation wiki page: Simulation Guidance Parameters TS0407 CESR measurements in CESR-c configuration in April, 2007 1.89 GeV - Ten 0.75 mA bunches, followed by ten empty bunches, 14 ns spacing Beam RMS size 0.16 x 0.016 x 12.6 mm. ECLOUD bunch time +- 3.4 sigma: 0.29 ns Elliptical beam pipe 4.5 x 2.5 cm QE 10%, 0.23 s.r. photons per beam particle (mistake: should have been 0.53 for dipole) 25k macroparticles generated per filled bunch SEY parameters: SEY=1.8, Epk = 310 eV 150 steps per bunch length, 300 steps between bunches 11 field calculations during each of 20 bunches Transverse field grid 7x7 spanning +- 3 sigma Field calculation includes beampipe image charges, no contribution from beam Four data sets: e+ & e-(+- 5mm/grid sources), e+(+-0.5mm/grid sources),e+(+-5mm/cloud sources ) Ten runs per data set: zero beam offset, +- X and Y beam offsets, each for both drift and 715 G dipole volumes ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  3. e+, Drift volume, Beam Y + 5 mm Beam offset observed in cloud particle energies ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  4. e+, Vertical Field, Drift, Beam Y +- 5 mm No pinch effect present ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  5. e+, Vertical Field, Drift, Beam Y +- 5 mm Marco found a gradient about 25% larger for this case ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  6. e+, Vertical Field, Drift, Beam Y +- 5 mm Grid Field Sources (21x21) Macroparticle Field Sources ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  7. e+, Horizontal Field, Drift, Beam X +- 5 mm Some pinch effect present ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  8. e+, Horizontal Field, Drift, Beam X +- 5 mm Gradient factor 3 smaller than vertical ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  9. e+, Vertical Field, Drift, Beam Y +- 0.5 mm Some “pinch effect” present ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  10. e+, Vertical Field, Drift, Beam Y +- 0.5 mm Gradient factor 6 larger than for offset +- 5mm (?) ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  11. e+, Horizontal Field, Drift, Beam X +- 0.5 mm Some “pinch effect” present ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  12. e+, Horizontal Field, Drift, Beam X +- 0.5 mm Gradient again factor 6 larger than for offset +- 5mm (?) ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  13. e-, Vertical Field, Drift, Beam Y +- 5 mm No pinch effect present ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  14. e-, Vertical Field, Drift, Beam Y +- 5 mm Marco found a gradient about 25% larger for this case ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  15. e-, Horizontal Field, Drift, Beam X +- 5 mm Some pinch effect present ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

  16. e-, Horizontal Field, Drift, Beam X +- 5 mm ECLOUD Electric Field Calculations/ J.A.Crittenden 14 January 2009

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