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Beam transfer considerations

Beam transfer considerations.

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Beam transfer considerations

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

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

  3. Implications for beam transfer systems • Specialised technical systems involved include • Kicker magnets • Septum magnets • Active beam dilution systems • Passive protection (absorber) elements • Beam dump blocks • Beam transfer lines Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

  4. 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 (largeren, larger Itot, ~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 Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

  5. 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 8: 3.8% slope TI 2: 2.4% slope Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

  6. LHC beam dump for LHC+ Present kickers with LHC+ beam Modified kickers with LHC+ beam Dump kicker upgrade… • Factor ~2 required in dilution for LHC+ at 7.5 TeV, 12.5 ns, 1.71011 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) Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

  7. Kicker impedance issues P [W/m] t [s] • 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) Measured impedances with / without ‘stripes ‘Measured’ deposited power on SPS extraction kickers with nominal LHC beam Metallic stripes printed directly on ferrites Solutions involve compromise: aperture/rise time/strength/impedance/heating Caspers, Gaxiola, Kroyer, Uythoven Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

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

  9. 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 b (~ 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. Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

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

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

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

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

  14. Extraction III: Resonant low-loss (CT-MTE) • Extraction using fast kickers (HK1 and HK2) and magnetic septa (MS) 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) Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

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

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

  17. 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) Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

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

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

  20. Transmission line kickers: design considerations dt = Lm / Z I = U / 2Z Lm = mo(w/h) lm Bm = mo I / h Deflection for nm magnets is q = nm U dt / (2 w Br) In a total length lt = nm dt Z h / w m0 Trade-off between rise-time, strength and length (dt  , lt ) Brennan Goddard CERN AB/BT LHC LUMI-06 19th October 2006

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