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Jonathan Smith, 1 st March, COLSIM, CERN 1 Recent Developments with ILC Collimator Wakefield Calculations Jonathan Smith (Lancaster University/Cockcroft.

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Presentation on theme: "Jonathan Smith, 1 st March, COLSIM, CERN 1 Recent Developments with ILC Collimator Wakefield Calculations Jonathan Smith (Lancaster University/Cockcroft."— Presentation transcript:

1 Jonathan Smith, 1 st March, COLSIM, CERN 1 Recent Developments with ILC Collimator Wakefield Calculations Jonathan Smith (Lancaster University/Cockcroft Institute)

2 Jonathan Smith, 1 st March, COLSIM, CERN 2 Introduction/Project Objectives ● LC-ABD WP5.3 (Nigel Watson)/EUROTeV WP2 (BDS) ● Collimation is crucial for beam delivery and detector protection/performance of a particle accelerator ● Quantification of longitudinal and transverse wakefield effects of collimators on the beam ● Optimization of collimator design ● Use and understanding of simulation tools, potential improvements and support of other projects ● Verification by test beam measurement

3 Jonathan Smith, 1 st March, COLSIM, CERN 3 Wakefield box ESA  z ~ 300  m – ILC nominal  y ~ 100  m (Frank/Deepa design) Magnet mover, y range =  mm, precision = 1  m 1500mm E beam =28.5GeV Slide reproduced from talk by Nigel Watson

4 Jonathan Smith, 1 st March, COLSIM, CERN 4  =  /2rad r=4.0mm 4, 4  324mrad r=1.4mm 3, 3  324mrad r=1.4mm 2, 2  =324mrad r=2.0mm 1, 1 Revised 4-May-2006 Beam viewSide view (“DESY sandwich”) Collim. #, slot h=38 mm 38 mm L=1000 mm 7mm  r=1/2 gap As per last set in Sector 2, commissioning Extend last set, smaller r, resistive WF in Cu cf. same r, tapered Slide reproduced from talk by Nigel Watson

5 Jonathan Smith, 1 st March, COLSIM, CERN 5  =  /2rad r=1.4mm 5, 4  166mrad r=1.4mm 6, 3  1 =  /2 rad  2 =166mrad r 1 =4.0mm r 2 =1.4mm 7, 2 r 1 =4.0mm r 2 =1.4mm   =289mrad   =166mrad 8, 1 Revised 4-May-2006 Beam viewSide view (“SLAC sandwich”) Collim.#, slot h=38 mm 38 mm 7 mm cf. collim. 4 smaller r 211mm cf. collim. 2, same r 31mm cf. collims. 4 and 6 133mm cf. collim. 7, and same step in/out earlier data Slide reproduced from talk by Nigel Watson

6 Jonathan Smith, 1 st March, COLSIM, CERN 6 Small improvement on the Chisq/n Run 1206 (ref. 1207) Multiplying each bunch by its ebpm_x ADC value

7 Jonathan Smith, 1 st March, COLSIM, CERN 7 Analytical estimate ● Stupakov says: ● Stupakov asserts that the h»b is met, but is this really valid?

8 Jonathan Smith, 1 st March, COLSIM, CERN 8 For SLAC collimators...

9 Jonathan Smith, 1 st March, COLSIM, CERN 9 Assessment/Familiarization of Simulation Tools ● MAGIC (easy to use tool for first comparison with new calculations) ● ECHO/ECHO3D – Thomas Weiland, Mikko Karkkainen (TEMF, Darmstadt) Igor Zagorodnov (DESY). Code development as part of EUROTeV project ● MAFIA – CDB and JS working on comparison with Cho Ng’s results (PAC 2001) ● GdfidL – Overlapping interest with David Miller and Alexei Liapine (UCL) as part of EUROTeV WP5 (Spectrometry) ● Additional software for research if required: – BCI/TBCI/ABCI (old CERN tools), XWAKE, XOOPIC – Tau3P, Omega, T3P (next generation SLAC codes) – Boundary Element (BEM) codes (Sapporo, Japan)

10 Jonathan Smith, 1 st March, COLSIM, CERN 10 EM Simulations with GdfidL

11 Jonathan Smith, 1 st March, COLSIM, CERN 11 (6 cells/sigma)

12 Jonathan Smith, 1 st March, COLSIM, CERN 12 (12 cells/sigma)

13 Jonathan Smith, 1 st March, COLSIM, CERN 13 Mesh stability: Collimators 1&2 ● Only 3 decent points at 300µm for most collimators ● More at 500µm ● 1mm ~ OK – can use spline fit on data to get an estimate – not done so far – further analysis to see if this takes us closer to ECHO/PBCI.

14 Jonathan Smith, 1 st March, COLSIM, CERN 14 What do we do about it? (1)

15 Jonathan Smith, 1 st March, COLSIM, CERN 15 What do we do about it? (2)

16 Jonathan Smith, 1 st March, COLSIM, CERN 16 Effect of mesh filtering…

17 Jonathan Smith, 1 st March, COLSIM, CERN 17 Misallignment

18 Jonathan Smith, 1 st March, COLSIM, CERN 18 Further collimator designs semi-circle, with[9]/without[10] flat, opposing demi-circles[10], 8 with flat[11].

19 Jonathan Smith, 1 st March, COLSIM, CERN 19 More possible collimators 7 with flat [13], half exponential[14], 13 with shallower angle[15] exponential profile[16], 13 with ellipse connecting 4mm and 1.4mm aperture[17] 13 with ellipse connecting beam pipe radius and 1.4mm aperture (also see 9) [18] half cosine taper [19], raised cosine taper [20], tanh tapers [21] (set typically to the length of collimator 6)

20 Jonathan Smith, 1 st March, COLSIM, CERN 20  166mrad r=1.4mm 12  =166mrad r =1.4mm 11  =166mrad r =1.4mm 10  166mrad r=1.4mm (1/2 gap) 6 Revised 27-Nov-2006 Beam viewSide view Collim.# h=38 mm 38 mm Roughened surface, compare with 12 As 10, in Ti-6Al-4V, polished, cf. 12 As 10, in OFE Cu, polished, cf. collim. 6, 13 Runs 3, 2007 Exists, from 2006 runs. For reproducibility ~211mm 1.4mm  =21mm   

21 Jonathan Smith, 1 st March, COLSIM, CERN 21 non-linear taper r=1.4mm 16?  1 =  /2 rad  2 =50mrad r 1 =4.0mm r 2 =1.4mm 15  1 =  /2 rad  2 =166mrad r 1 =4.0mm r 2 =1.4mm 14  1 =  /2 rad  2 =166mrad r 1 =4.0mm r 2 =1.4mm 13 Revised 27-Nov-2006 Beam viewSide view Collim.# h=38 mm 38 mm cf. ? Polished, cf. collim. 13 Polished, cf. collims. 7, 11, 13 Polished, cf. collim. 7, 12, 13 Ti6Al4V OFE Cu =21 mm Form t.b.d. = 0.6    Ti6Al4V Runs 3, 2007 ~52 mm =21 mm  ~52 mm =21 mm   ~125 mm =21 mm

22 Jonathan Smith, 1 st March, COLSIM, CERN 22 Variation of collimator kick with bunch length

23 Jonathan Smith, 1 st March, COLSIM, CERN 23 WB's suggestion: Chop this bit off as beam will never see wake that has travelled this far from the bunch

24 Jonathan Smith, 1 st March, COLSIM, CERN 24 Two possibilities: s_ma x s_maxs_max “colimator 23” “colimator 22”

25 Jonathan Smith, 1 st March, COLSIM, CERN 25 Longitudinally Asymmetric?

26 Jonathan Smith, 1 st March, COLSIM, CERN 26 Results...

27 Jonathan Smith, 1 st March, COLSIM, CERN 27 Cylindrical jobs... ● W modal decomposition ● See Adriana's talk... ● Jobs still running ● w(s,r,r', θ, θ')→w(s,r,θ,m ) ● Useful for rectangular geometry?

28 Jonathan Smith, 1 st March, COLSIM, CERN 28 GdfidL & PBCI ● TEMF working on ECHO/PBCI – 3D, moving mesh, conformal, non-dispersive solver s/σ σ/Δz=6 W ║ (s)/(V/pC) GdfidL PBCI With thanks to Mikko Kärkkäinen


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