nominal ps beam for the future lhc electron cloud build-up visible on electrostatic pick-ups
DESCRIPTION
OBSERVATIONS OF ELECTRON CLOUD BUILD-UP IN THE CERN PS. R. Cappi, E. Metral, G. Metral, M. Giovannozzi SPS Studies Working Group meeting. Nominal PS beam for the future LHC Electron cloud build-up visible on electrostatic pick-ups Effect of a solenoidal field - PowerPoint PPT PresentationTRANSCRIPT
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the future LHC Electron cloud build-up visible on electrostatic pick-ups
Effect of a solenoidal field Effect of a gap in the bunch train Simulations by F. Zimmermann Next studies
OBSERVATIONS OF ELECTRON CLOUD
BUILD-UP IN THE CERN PS
R. Cappi, E. Metral, G. Metral, M. R. Cappi, E. Metral, G. Metral, M. GiovannozziGiovannozzi
SPS Studies Working Group meetingSPS Studies Working Group meeting
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the furture LHC (1/6) Nominal PS beam for the furture LHC (1/6)
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I [e10]
B [Gauss]
inj1 +10msC180
inj2 -10msC1360
inj2 +5msC1375
ej -6msC2389
Magnetic field and double-batch injection
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the furture LHC (2/6) Nominal PS beam for the furture LHC (2/6)
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Time [ms]
H54
H64
V75
V85
PSB TT2
inj1 +10msC180
inj2 - 10msC1360
inj2 + 5msC1375
ej - 6msC2389
Normalised transverse emittances at 1
without bunch rotation!
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the furture LHC (3/6) Nominal PS beam for the furture LHC (3/6)
RF gymnastics
At low energy (1.4 GeV kinetic energy)
1st injection => 3 bunches (H7) 2nd injection => 3 bunches (H7) Triple splitting => 6 × 3 = 18 bunches (H21)
At high energy (26 GeV/c momentum)
1st double splitting => 18 × 2 = 36 bunches (H42)
2nd double splitting => 36 × 2 = 72 bunches (H84) with
Bunch rotation => 72 bunches (H84) with
=> 6 bunches (H7)
eVs35.0l
ns16bns4b
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the furture LHC (4/6) Nominal PS beam for the furture LHC (4/6)
ns/div300
The 72 bunches at PS ejection
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the furture LHC (5/6) Nominal PS beam for the furture LHC (5/6)
Only 1 measurement is still missing => the transverse emittances in TT2 in the presence of bunch rotation
H - plane V - plane
Emittance measurements using the Semfils in TT2 without bunch rotation
Elias Metral, SSWG meeting, 21/11/2000
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Nominal PS beam for the furture LHC (6/6) Nominal PS beam for the furture LHC (6/6)
Emittance measurements using the Semfils in TT2 with bunch rotation
H - plane
=> Electrons are created ...
Elias Metral, SSWG meeting, 21/11/2000
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Electron cloud build-up visible on electrostatic pick-ups Electron cloud build-up visible on electrostatic pick-ups (1/(1/55))
Nominal beam seen on the pick-up 208 in TT2
Without solenoid
With solenoid~ 50-100 G
cf. W. Hofle
Elias Metral, SSWG meeting, 21/11/2000
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Electron cloud build-up visible on electrostatic pick-ups Electron cloud build-up visible on electrostatic pick-ups ((22//55))
Pick-up 208 in TT2 (with and without solenoid)
Pick-up 03 in the PS (in the last turns)
Elias Metral, SSWG meeting, 21/11/2000
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Electron cloud build-up visible on electrostatic pick-ups Electron cloud build-up visible on electrostatic pick-ups ((33//55))
Nominal beam (but with 84 bunches) seen on the pick-up 208 in TT2
Without solenoid
With solenoid~ 50-100 G
Elias Metral, SSWG meeting, 21/11/2000
11
Electron cloud build-up visible on electrostatic pick-ups Electron cloud build-up visible on electrostatic pick-ups ((44//55))
Nominal beam (but with 84 bunches) seen on the pick-up 03 in the PS
=> No coupled-bunch instabilities...
Elias Metral, SSWG meeting, 21/11/2000
12
Electron cloud build-up visible on electrostatic pick-ups Electron cloud build-up visible on electrostatic pick-ups ((55//55))
Effect of a gap in the bunch train
=> Helpful as predicted (cf. Roberto’s pictures)
Simulations by F. Zimmermann
=> It predicts the electron cloud build-up in both the PS and TT2 (cf. Frank’s pictures)
Next studies
See if the beam becomes unstable at the end of TT2 (it does not seem to be the case according to recent SPS MDs)
Try to have a clean measurement of the transverse emittances in TT2 using the Semfils => capture of the e-...