E. Benedetto SC meeting 19/3/15 Update on the LIU curve emittance vs. intensity

E.Benedetto, LIU curve Update Simulations with PTC-Orbit On a straight line & depends on longitudinal emittance BUT: the slope for 1.20eVs is a factor 25% lower 1.2 eVs Nov 2014 and HB workshop

E.Benedetto, LIU curve Update Space-Charge simulations (PTC-Orbit) Transversely MATCHED distribution (Gaussian) (*) – With a given emittance – Scan on the Intensity Let it evolve for ~7ms, during fall of the chicane bump Quadrupolar errors at the chicane magnets + Eddy currents + Compensation QDE3, QDE14 (time varying) – Beta-beating (mostly in vertical) corrected – Excitation of half-integer corrected – Excitation of the integer line (*) In longitudinal (for the time being): I let a “rectangular” distribution evolve in an accelerating bucket, h1+h2. NOT YET optimized… Nov 2014 and HB workshop

E.Benedetto, LIU curve Update Space-Charge simulations (PTC-Orbit) 200 SC nodes 2.5 Direct SC module 128x128x k macroparticles Emittance reached at the end of the chicane bump is ~“independent” of the starting value I=350 ppb Initial and final longitudinal distribution Nov 2014 and HB workshop

E.Benedetto, LIU curve Update Space-Charge simulations (PTC-Orbit) H and V Tune spread Initial  Qx extending below the integer  blow-up Red: initial 350e10 ppb,1  m Blue: final (after 7ms) for the same beam. Green: initial 350e10 ppb, 1.7  m.. Nov 2014 and HB workshop

E.Benedetto, LIU curve Update What has still to be done Scan working point  EB ongoing, see next slides Integration of the injection process – Transverse  Jose – Longitudinal  Vincenzo ongoing Benchmark code vs. today injection  done in the past by V. Raginel but not conclusive due to uncertainties in measurements, new MDs will be done this year +GP simulations?

E.Benedetto, LIU curve Update Scan with working point

E.Benedetto, LIU curve Update However…

Conclusions Working point has an effect – If Qx is increased, brightness is improved Is it possible to inject at (4.43,4.60)?, also (4.33,4.55) Is it possible to produce in a controlled way (i.e. no successive blow-up) any emittance sitting on the curve? – beam should be as Gaussian as possible Spikes (back again…) origin to be understood – but I’m confident they do not invalidate results – perhaps give more blow-up -

Appendix

E.Benedetto, LIU curve Update How to preserve small emittance? – Optimize optics parameters – Optimize initial distribution (also longitudinal!) – Optimize KSW – Minimize foil crossings – Optimize PSB working point Small Emittance - High Brightness What shall we expect in case of errors/non optimal parameters?

E.Benedetto, LIU curve Update Working point during PSB cycle

E.Benedetto, LIU curve Update Edge effects (rectangular magnets) Proposed corrugated Inconel vacuum chamber new baseline (ceramic in the original design) Influence on beam dynamics of induced Eddy currents: – Delay of ~50us – Higher order field components (sextupolar) Quadrupolar feed-down Excitation 3 rd order resonance  -- -- BSW4 BSW3BSW2 BSW1 3D magnet simulation by B. Balhan, J. Borburgh Perturbation by the chicane magnets E. Benedetto, et al. IPAC14

E.Benedetto, LIU curve Update Shape for the chicane ramp down Realistic shape with a 125Hz content (So far, assumed linear decay in 5ms) Correction for V Beta-Beating has been computed Almost identical results (blow-up and/or losses) than with the linear decay Input from D. Aguglia, D. Nisbet Computed strength in the QDE3, QDE14 and in the other quadrupoles BSW ramp-down function and sextupolar component generated by eddy-currents E. Benedetto, et al. IPAC14