mkp-i: impedance considerations
DESCRIPTION
MKP-I: Impedance considerations. C. Zannini , H. Bartosik , G. Rumolo , B. Salvant M. Barnes, T. Kramer, L. Sermeus. Overview. Simulation model Simulation results Proposed options Beam coupling impedance considerations Transverse impedance Longitudinal impedance Shielding - PowerPoint PPT PresentationTRANSCRIPT
MKP-I: Impedance considerations
C. Zannini, H. Bartosik, G. Rumolo, B. Salvant
M. Barnes, T. Kramer, L. Sermeus
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
3D simulation model of the MKP-I
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
Proposed options
Main Parameters
Option 1 Option 2 Option 3 Option 4
Number of magnet cells
5 5 5 7
Magnet cell length
36 mm 45 mm 45 mm 32 mm
Number of magnets
10 8 10 10
Vertical gap 45 mm 45 mm 56 mm 56 mm
Total magnetic length
1.8 1.8 2.25 2.25
X_beam 50 mm 50 mm 50 mm 50 mm
sd 100 mm 100 mm 100 mm 100 mm
sdxbeam
Beam coupling impedance of the proposed options
Beam coupling impedance of the proposed options
Beam coupling impedance of the proposed options
Beam coupling impedance of the proposed options
Option 3 and Option4 result the more convenient solutions
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
SPS transverse impedance budget
Vertical impedance: Comparison between present MKPs and MKP-I system
The new MKP-I system has a slightly larger vertical impedance per meter length
Smaller vertical aperture and shorter magnet length
SPS transverse impedance budget
Vertical impedance: Comparison between present MKPs and MKP-I system
Smaller vertical aperture and shorter magnet length
The new MKP-I system has a slightly larger vertical impedance per meter length
SPS transverse impedance budget
MKP-I system would significantly increase the vertical impedance of SPS kickers
SPS transverse impedance budget
MKP-I system would significantly increase the vertical impedance of SPS kickers
SPS transverse impedance budget
Case Zyeff kickers [MΩ/m] Zyeff SPS [MΩ/m]
Present model 7.57 18.51
With MKPI option 1 8.25 (≈+9%) 19.19 (≈+4%)
With MKPI option 3 8.09 (≈+7%) 19.03 (≈+3%)
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
SPS longitudinal impedance Comparison between present MKPs and MKP-I system
The new MKP-I system has a slightly larger vertical impedance per meter length
Smaller vertical aperture and shorter magnet length
SPS longitudinal impedance Comparison between present MKPs and MKP-I system
The new MKP-I system has a slightly larger vertical impedance per meter length
Smaller vertical aperture and shorter magnet length
SPS longitudinal impedance
MKP-I system would significantly increase the longitudinal impedance of SPS kickers
SPS longitudinal impedanceComparison between present SPS kickers and MKP-I system
MKP-I system would significantly increase the longitudinal impedance of SPS kickers
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
Shielding: proposed options
Shielding proposed options
“beam screen like” shielding with wires (solution to be developed)Ceramic plate with titanium coating
M. Barnes, T. Kramer, L. Sermeus
For electron cloud mitigation it is strongly recommended that the beam does not see the ceramic (see MKIs in LHC)
G. Iadarola, G. Rumolo
Ceramic plate with titanium coating: preliminary simulations
shielding1 shielding2
Ceramic plate with 30 nm titanium coating Ceramic plate with 10 μm titanium coating
shielding1 shielding2
Ceramic plate with 30 nm titanium coating Ceramic plate with 10 μm titanium coating
Ceramic plate with titanium coating: preliminary simulations
shielding1 shielding2
Ceramic plate with 30 nm titanium coating Ceramic plate with 10 μm titanium coating
Ceramic plate with titanium coating: preliminary simulations
shielding1 shielding2
Ceramic plate with 30 nm titanium coating Ceramic plate with 10 μm titanium coating
Ceramic plate with titanium coating: preliminary simulations
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
Beam induced power loss
Beam induced heating
The calculations for MKEs have been successfully benchmarked against beam induced heating observations during 2012
Beam induced power loss
Beam induced heating
Present MKPs could strongly suffer of beam induced heating with high intensity beam
Beam induced power loss
Beam induced heating
Present MKPs could strongly suffer of beam induced heating with high intensity beam
Even worst for MKP-I
Beam induced power loss
Beam induced heating
The shielding option (ceramic plate with titanium coating is not very efficient to reduce the beam induced power loss)
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
Transverse stability: Q20HEADTAILsimulation
MKP-I option3 wake model
Transverse stability
HEADTAIL simulations from H. Bartosik
Present wake model reproduces the instability behavior (PhD thesis of H. Bartosik, to be published)
The new MKP-I kicker system would reduce the transverse vertical instability threshold of ≈ 5%
Overview• Simulation model
• Simulation results– Proposed options
• Beam coupling impedance considerations– Transverse impedance– Longitudinal impedance– Shielding
• Beam induced power loss and transverse stability– Beam induced power loss– Transverse stability considerations– Beam coupling impedance with beam out
Longitudinal impedance: beam out
Having the circulating beam out of the magnet would dramatically reduce the impedance
xout
Transverse impedance: beam out
xout
Having the circulating beam out of the magnet would dramatically reduce the impedance
Info from Benoit : very preliminary studies for the septum
• Preliminary design provided by Bruno Balhan last week• Coarse approximations had to be made due to the complexity of the device,
and lack of available information:• Laminations replaced by ferrites 4A4• Longitudinal segmentation ignored
Magnetic laminations are partially shielded by steel holders Several significant undamped longitudinal modes from 50 MHz onwards (i.e. fully in the beam spectrum) Very large upstream and downstream aperture (frequencies above 500 MHz will escape in the beam pipe) The impedance of this septum should be fully checked and it is likely that it should be optimized
Summary and conclusions• The unshielded MKP-I would significantly contribute both to
the longitudinal and transverse SPS beam coupling impedance.• A reduction of about 5% of the transverse instability threshold
has been estimated.• The MKP-I with the present design could limit future operation
with 25 ns beams due to the beam induced heating (similarly to the non-serigraphed MKE in 2012).
• Circulating beam out would dramatically reduce both longitudinal and transverse impedance solving both heating and stability issues.
• Preliminary simulations seems to indicate that the shielding option (ceramic plate with titanium coating) is not very efficient to reduce the beam induced heating.
Thank you for your attention
Appendix
SPS transverse impedance budget
Vertical impedance: Comparison between present MKPs and MKP-I system
SPS transverse impedance budget
Vertical impedance: Comparison between present MKPs and MKP-I system
SPS longitudinal impedance Comparison between present MKPs and MKP-I system
SPS longitudinal impedance Comparison between present MKPs and MKP-I system
SPS longitudinal impedance: normalized impedance
Effect of magnet length
For a given cell length and total magnetic length in terms of beam coupling impedance a smaller number of magnets is more convenient
Effect of magnet length
For a given cell length and total magnetic length in terms of beam coupling impedance a smaller number of magnets is more convenient
Effect of magnet length
For a given cell length and total magnetic length in terms of beam coupling impedance a smaller number of magnets is more convenient
Effect of magnet length
For a given cell length and total magnetic length in terms of beam coupling impedance a smaller number of magnets is more convenient
Effect of the beam position
The peak due to the TEM mode increases as the beam get closer to the inner conductor
The broadband peak due to the ferrite decreases as the beam get closer to the inner conductor
[mm]
Effect of the beam position
xbeam
[mm]
Effect of the beam position
The transverse impedance decreases as the beam get closer to the inner conductor
xbeam
Effect of the beam position
The transverse impedance decreases as the beam get closer to the inner conductor
xbeam
Effect of the screen distance
Effect almost negligible for the longitudinal impedance
sd
Effect of the screen distance
Effect almost negligible for the longitudinal impedance
sd
Effect of the screen distance
Shift to lower frequency and reduction of the broadband peak of the ferrite loaded structure on the vertical dipolar impedance
sd
Effect of the screen distance
Shift to lower frequency and reduction of the broadband peak of the ferrite loaded structure on the vertical dipolar impedance
sd
Beam induced power loss
Beam induced heating
The calculations for MKEs have been successfully benchmarked against beam induced heating observations during 2012
Beam induced power loss
Beam induced heating
Present MKPs could strongly suffer of beam induced heating with high intensity beam
Beam induced power loss
Beam induced heating
Present MKPs could strongly suffer of beam induced heating with high intensity beam
Even worst for MKP-I
Beam induced power loss
Beam induced heating
The shielding option (ceramic plate with titanium coating is not very efficient to reduce the beam induced power loss)