PS injection at 2 GeV

W. Bartmann, J. Borburgh, S. Gilardoni, B. Goddard, L. Sermeus, R. Steerenberg

PS-LIU meeting, 27-Aug-2013

2 GeV PSB ejection and transfer to the PS 2

Aim of the PSB-PS transfer upgrade• All beams to be transferred at 1.4 and 2 GeV (until LS2 also 1.0 GeV in BT and

BTM/BTY for ISOLDE)– Septum and kicker strength increased by 30% (Bρ2GeV /Bρ1.4GeV)

– Can relax PS injection kicker fall time for LHC beam but not for HI beam– LHC beam can be injected with existing kicker in short-circuit mode with longer fall time– HI beam injection at 2 GeV requires additional kicker in SS53

• Match optics at PS injection to reduce emittance blow-up due to dispersion mismatch– Vertical dispersion remains mismatched due to the vertical displacement of the four PSB

rings (Dy < 0.5 m)– Horizontal dispersion is presently not matched; install one additional quadrupole in BTP

line to match the line to the PS injection optics

• Optimise optics for different beams– Requires ppm capability of HW (i.e. upgrade of BTP)

18-Sept-2012

PS injection at 2 GeV 3

PS injection upgrade• KFA45

– Can be used in short circuit mode to increase kick strength but at the expense of the rise/fall time

– Additional kicker in SS53 needed to inject also HI beams at 2 GeV

27-Aug-2013

PS injection at 2 GeV 4

KFA53• As fast as KFA45• Delay line type magnets, short circuited• Already bumper in SS53, 730 mm between flanges• Coated ceramic shielding plates• RG220 PFL with 40 kV, higher attenuation than SF6 cables

(KFA45) transmission cable length < 50 m• SF6 would allow to run with one generator in case of failure,

not with RG220, market survey to be launched

27-Aug-2013

PS injection at 2 GeV 5

Kicker parametersParameter unit KFA45 value

(terminated)KFA45 value

(short-circuited)KFA53 value

(short-circuited)

Deflection angle (nominal) mrad 4.3 4.3 1.3

ʃ B.dl (max) T.m 0.0314 0.0601 0.0187

Deflection angle (max) @ 1.4 GeV mrad 4.395 8.4

Deflection angle (max) @ 2 GeV mrad 3.38 6.5 2

System impedance Ω 26.3 26.3 15

PFL voltage (max) kV 80 80 40

Magnet aperture (w × h) mm × mm 150 × 53 150 × 53 140 × 59

Beam aperture (w x h) mm × mm 140 × 53

Kick rise time (1-99) % ns 46 82 46

Kick fall time (99-1) % ns 96 92 92

Kick length (max) ns 2600 2600 2600

Kick flat-top ripple % ± 2 ± 3 ± 3

Post kick ripple % ± 1.25 ± 1.5 ± 1.5

27-Aug-2013

PS injection at 2 GeV 6

Septum upgrade• SMH42

– Longer septum taking full SS42– Bumper to be integrated in vacuum tank– Bumper upgrade to collapse bump in ~half the time to reduce

continuous losses and to improve field quality because of eddy current effects for “bumper septum”

Eddy current septa: injection septum as well as bumper septum

27-Aug-2013

PS injection at 2 GeV 7

Septum and bumper parametersSeptum Bumper

Physical length (mm) 940 300

Magnetic length (mm) 942 262

Septum thickness (mm) 5 ~ 5

Nominal septum position w.r.t orbing beam centre (mm) 56

Septum position range (mm) 49 – 63

Nominal angular septum position (mm) 10

Angular septum position range (mm) 8-15

Magnet gap height (mm) 70 76

Magnet gap width (mm) 113 150

Nominal deflection angle (mrad) 55 13

Bgap (T) 0.54 0.461

Integrated field strength (T.m) 0.51 0.121

Peak current for nominal deflection (kA) 30.3 27.9

Pulse width, (ms) full sine, 2.0 half sine, 1.0

Magnet inductance (µH) 1.9 0.7

Magnet resistance (mΩ) 0.127-Aug-2013

PS injection at 2 GeV 8

HW upgrade cost

Cost duration remarks

kCHF MY months

PS injection septum 731 2.3 30

PS septum bumper 84 0.4 12 Tbc.

Additional PS injection kicker (SS53)

1850 3.7 48 Tbc.

Total 2665 6.4

27-Aug-2013

PS injection at 2 GeV 9

Optics solutions• Match horizontal dispersion to PS injection optics to reduce emittance blow-up

– Improve luminosity for LHC beams– Reduce losses in PS for HI beams

• Vertical dispersion unavoidably mismatched– Keep it low for all 4 PSB rings

• Avoid aperture bottlenecks in the line to be able to fully deploy L4 intensities and above– Mainly relevant for the large emittance beams

• Squeeze beams at PS injection– Only for HI large emittance beams– Reduce radiation, equipment aging and beam loss– Have to change PS optics at injection (MD this year)

27-Aug-2013

PS injection at 2 GeV 10

LHC beams – horizontal

LHC beam matched to nominal PS injection optics to avoid emittance growth

No aperture bottlenecks in the line

27-Aug-2013

PS injection at 2 GeV 11

LHC beams – vertical

No aperture bottlenecks in the line

27-Aug-2013

PS injection at 2 GeV 12

HI beams –horizontalHI beam matched to dedicated injection optics to reduce beam losses

Aperture for beams to PS in line OK due to smaller beam size at 2 GeV

Aperture for ISOLDE beam remains the same

27-Aug-2013

PS injection at 2 GeV 13

HI beams - vertical

Aperture in the line looks OK – beam size in injection septum to be checked in MD

27-Aug-2013

PS injection at 2 GeV 14

Injection loss MD 2013

27-Aug-2013

Wrong BTP model, tried to inject a horizontally too big beam:

Emittance measured in PS: (1σ rms, normalised) [µm] Nominal optics Dedicated optics

Horizontal emittance 3.6 6.4

Vertical emittance 2.9 2.7

• These settings fit only 1.4 σ beam

• 70% measured transmission correspond to 1.55 σ

2 GeV PSB ejection and transfer to the PS 15

Conclusion• Solution for injection of all beams at 2 GeV identified

• Main changes for HW:– PS injection septum – new design with bumper in vacuum – PS injection kicker KFA53 – new HW

• Optics– With additional quadrupole and new arrangement line optics can be matched to PS– Line has flexibility to adapt optics for different needs of LHC and HI beams

• MDs required to see if loss improvement justifies new quadrupoles– MD in 2013 used settings from wrong MADX model– The difference in transmission between wrong and correct model corresponds to the measured

losses and emittances– Another MD needed after the startup

18-Sept-2012