1. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Beam transfer considerations The various mooted upgrades of the CERN accelerator complex up to and including the LHC will necessitate substantial modifications to the Beam Transfer systems, comprising extraction elements, transfer lines, injection elements and beam dumps. A general overview of the present performance reach, technological challenges and areas for study of the Beam Transfer systems is given, highlighting areas which are expected to be most relevant to the different CERN upgrade proposals. Implications for beam transfer systems Performance issues –Focus on kicker systems Some details of PS2/PS2+ studies Areas of interest for R&D Many thanks to V.Mertens, J.Borburgh, L.Ducimètiere, T.Fowler, M.Benedikt, J.Uythoven and others

2. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Upgrades to many beam transfer systems….. PS2 1.4/3.5  50/75 GeV SPL 0  3.5 GeV LEIR 4.2  72 MeV/u Source+LINAC3 0  4.2 MeV/u SPS+ 50/75  1000 GeV LHC+ 1  7.5 TeV LHC+ extraction and dump at 7.5 TeV SPS+ extraction 1 TeV SPS+ to LHC+ transfer and injection at 1 TeV PS2 injection, extraction and transfer SPS+ injection at 50-75 GeV

3. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Implications for beam transfer systems PS2/PS2+SPS+LHC+ Injection1.3 GeV: fast (ions) 3.5 GeV: fast (if RCS) or 3.5 GeV: H- (if SPL) 50-75 GeV: fast1 TeV: fast Extraction50-75 GeV: fast, slow (3 rd integer), CT (MTE) 1 TeV: fast, slow?7.5 TeV: fast Transfer1.4 - 3.5 GeV (from PS/RCS/SPL) 50 – 75 GeV (to EA) 50-75 GeV (from PS2 with low-  for ions?) 1 TeV (TT20/TT41?) 1 TeV (4 T SC versions of TI 2/8) Beam dump1.4 - 75 GeV: ~1.5 MJ0.05 - 1 TeV: ~14 MJ1 - 7.5 TeV: ~1100 MJ Specialised technical systems involved include –Kicker magnets –Septum magnets –Active beam dilution systems –Passive protection (absorber) elements –Beam dump blocks –Beam transfer lines

4. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Expected technological concerns/limitations Injection –High energy (3.5 GeV) H- injection system in PS2 –SPS injection system upgrade to 50/75 GeV –LHC injection system upgrade to 1 TeV Extraction systems –Multiple extraction systems from PS2/SPS –SPS fast extraction at 1 TeV (B.dl) Beam dumping –Aperture, dilution and absorption for LHC+ dump (larger  n, larger I tot, ~same E) –Machine protection for beam in gap in SPS+ and LHC+ –Radiation and “co-habitation” issues for internal dumps (PS2/SPS+) –Aperture and extraction system design for external dumps (PS2/SPS+) Transfer lines –Bending radius and slopes for SC magnets (TI 2/8+ SPS+ to LHC+) Kicker impedance –Already an issue in the SPS with existing kickers

5. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 SPS+ to LHC+ transfer Needs SC dipoles of about 4.0 T, with beam aperture of ~50x20 mm. –Tunnels have some slope and kinks….cryo issues? –Space very limited, “QRL” integration an issue? TI 2: 2.4% slope TI 8: 3.8% slope

6. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 LHC beam dump for LHC+ Factor ~2 required in dilution for LHC+ at 7.5 TeV, 12.5 ns, 1.7  10 11 p+/bunch - new MKB dilution kicker systems - higher sweep frequency & strength  factor ~2 in installed length (now 22 m…)? - possible increase in triggering reaction time (add 1 turn) Dump kicker upgrade… Present kickers with LHC+ beamModified kickers with LHC+ beam

7. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Kicker impedance issues Caspers, Gaxiola, Kroyer, Uythoven Kicker impedance –Major contribution to machine impedance  possible intensity limitations –Longitudinal impedance  beam induced heating of the kicker ferrites Above 125 ºC ferrite temperature magnets loose kick strength Mechanical damage of systems not conceived for bake-out Heating of SPS kickers measured with LHC beam –600 W/m average deposited power –>100 ºC temperature rise  measured loss of kick strength –Significant impedance (9 extraction kickers presently in SPS) Issues actively being addressed include –Cooling of kicker ferrites (applied to installed extraction kicker magnets) –Impedance reduction (stripes, coated ceramic chambers, inserts) –Fewer installed kickers (short-circuit  larger K and dt) Solutions involve compromise: aperture/rise time/strength/impedance/heating Measured impedances with / without ‘stripes Metallic stripes printed directly on ferrites ‘Measured’ deposited power on SPS extraction kickers with nominal LHC beam P [W/m] t [s]

8. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Present PS/SPS/LHC kicker system parameters

9. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 PS2: injection/extraction systems Assumptions made to define an entry point –Regular (FODO) lattice in the injection/extraction regions, with 90º phase advance and 21 m cell length. –7 (8.5 m) ‘free’ per half-cell available to accommodate beam transfer elements –Dispersion function matched to ~zero in these regions (assume < 0.5 m). –Enlarged quadrupoles with 85 mm good field regions (c.f. 50 mm assumed for the regular quads…). –Extraction trajectory via enlarged quadrupole coil windows, a la SPS –Kicker and septum elements outside half-aperture of 50 mm at 33 m  (~ 300 .mm.mrad acceptance). –Injection energy 1.4/3.5 GeV, extraction energy 50/75 GeV. –Optics and layout identical for all versions at all energies. –H/V beam emittances 15/8 .mm.mrad. –From the SPL, the H- beam emittance is assumed to be 1 .mm.mrad. –Lattice quadrupole yokes are 700 x 700 mm for standard types, and 900 x 900mm for enlarged types. The enlarged types are 2.2 m long, c.f 1.75 m for the standard elements.

10. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Injection: fast p+/ions, 1.4 - 3.5 GeV Requires 2 half-cells for fast injection system (with 90º optics)

11. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Injection: H- multi-turn, 3.5 GeV Requires 2.5 - 3 half-cells for h- injection system (with 90º optics)

12. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Extraction I: slow resonant (3 rd integer) Extraction using electrostatic septa (ES) and magnetic septa (MS)

13. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Extraction II: fast single-turn Extraction using fast kicker (HK2) and magnetic septa (MS)

14. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Extraction III: Resonant low-loss (CT-MTE) Overall require 9 half-cells for extraction systems (with 90º optics) (note that 3 of these are ~empty, and could possible accommodate a beam dump) Extraction using fast kickers (HK1 and HK2) and magnetic septa (MS)

15. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Beam dump: Internal or external? External dump looks like another fast extraction channel.... –Except that the aperture must be OK for 1.3 GeV beams –Makes life difficult for extraction septa (much larger gaps) Internal dump is easier and more compact…. –Issues of high activation in the ring –Proximity to kickers…(difficulties seen in SPS in 2006). Need in any case 2 or 3 half-cells for the beam dump

16. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Tentative PS2 system parameters PS2 inj PS2 extr ~14 half-cells total

17. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Areas of interest for R&D Impedance and shielding –Ceramic chamber coatings, surface treatments, geometries, effect on rise times –Ferrite surface treatments, stripes Switch technology –Fast solid state high current thyristor devices High Voltage technology –Flashover under vacuum (magnets, connectors, ceramic chambers) Magnetic materials –High saturation ferrites –High Currie-temperature vacuum-compatible ferrites –Ultra-thin laminations, tape-wound cores Coil technology –in-vacuum insulation “New” beam transfer concepts –C-type extraction kickers Beam intercepting protection devices –Materials and geometries for increased robustness –Consumable/single-use devices Sometimes contradictory requirements which have to take into account various design considerations (bakeout etc.)  parallel development essential Serious R&D requires resources (additional to those presently available)

18. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 fin

19. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 PS2: kicker Trade-off in parameters AND cost can be made…. –Iterations involving: Machine energy Bunch filling schemes Lattice optics and space Parameters from other injection/extraction elements (e.g. septa width) Injection and extraction concepts Technological limitations (switches, magnetic materials, impedance reduction, …) Possible PS2 extraction kicker configurations

20. Brennan Goddard CERN AB/BT LHC LUMI-06 19 th October 2006 Transmission line kickers: design considerations dt = L m / Z I = U / 2Z L m =  o (w/h) l m B m =  o I / h Deflection for n m magnets is  = n m U dt / (2 w B  ) In a total length l t = n m dt Z h / w  0 Trade-off between rise-time, strength and length ( dt  , l t   )