status on hl-lhc heating
DESCRIPTION
Status on HL-LHC heating. B. Salvant for the impedance team Many thanks to: Gianluigi Arduini, David Belohrad , Riccardo de Maria, Stephane Fartoukh, Giovanni Iadarola, Thibaut Lefevre, Elias Metral, Nicolas Mounet, Giovanni Rumolo, Ralph Steinhagen , Simon White, Carlo Zannini. - PowerPoint PPT PresentationTRANSCRIPT
Status on HL-LHC heating
B. Salvant for the impedance team
Many thanks to: Gianluigi Arduini, David Belohrad, Riccardo de Maria, Stephane Fartoukh,
Giovanni Iadarola, Thibaut Lefevre, Elias Metral, Nicolas Mounet, Giovanni Rumolo, Ralph Steinhagen, Simon White, Carlo Zannini.
HL-LHC WP2 task leader meeting - October 19th 2013
Agenda
• Beam spectra for 800 MHz?• Scaling to PIC1, PIC2, US1, US2• Potential issues for hardware (difficult to
predict)
bunch flattening of the LHC beam at 7 TeV(ESME Simulations)
Chandra Bhat 3
Vrf(400MHz)=16MV
E vs t
Line charge Distribution
Energy Distribution
E vs t
Line charge Distribution
Energy Distribution
Vrf(400MHz)=16MV +Vrf(800MHz)=8.5MV
Normal Bunch Flattened BunchMountain Range
RMS Bunch Length vs Time
RMS Energy Spread vs Time
2.5 eVs
z=7.5cm
E=3.2GeVrms=0.72GeV
lb=41cm
E=2.6GeVrms=0.6GeV
C. Bhat 2009
Bunch with 800 MHz
Function proposed by Elena:Rho=exp(-t4/(2*sig4)) with sig=0.45 ns
Function proposed by Stephane:Rho=(1+erf(4*(1-abs(t)/0.5e-9)))/2
With fitted parameters to the curve obtained in ESME
Flat bunches (C. Bhat, 2009) quotedby F. Zimmermann and S. Fartoukh
Vrf(400MHz)=16MV +Vrf(800MHz)=8.5MV
Bunch in 400 MHz (coarse fit from Chandra)
Power spectra
Flat bunches excite less power below 1.1 GHz, but more above
(4*rms=1 ns)(4*rms=1 ns)(4*rms=1 ns)(4*rms=1.24 ns)(4*rms=1.2 ns)
Power spectra
Flat bunches have less power below 1.1 GHz, but more above (also measured during MD on 28 Nov 2012)
(4*rms=1.15 ns)(4*rms=1.15 ns)(4*rms=1 ns)(4*rms=1.25 ns)(4*rms=1.2 ns)
Power loss dependence on various bunch distributions?
gaussian (4sig=1 ns)cos^2 (4*rms=1 ns)
gaussian (4sig=1.1 ns)cos^2 (4*rms=1.1 ns)
gaussian (4sig=1.2 ns)cos^2 (4*rms=1.2 ns)
gaussian (4sig=1.3 ns)cos^2 (4*rms=1.3 ns)
parabolic (fit Chandra, rms=0.25 ns)exp(-t^4) (fit Chandra, rms=0.31 ns)
1+erf(4*(1-|t|/0.5e-9) (fit Chandra, rms=0.3 ns)
measured 2012 (reference)
0.9 1 1.1 1.2 1.3 1.4
factor from reference measured in 2012
Flat bunches not far from single RF situation in terms of heating for very broadband impedances (constant over frequency). Effect will depend on the spectrum of each device.
Agenda
• Beam spectra for 800 MHz?• Scaling to PIC1, PIC2, US1, US2• Potential issues for hardware (difficult to
predict)
Increase in heat load only from intensity increase
*Narrow band is a worst case scenario assuming that the resonance stands exactly at a multiple of 40 MHz
Increase in heat load only from intensity increase (table)
Factor from situation before LS1
Nominal (25 ns)
ultimate (25 ns)
Before LS1 (50
ns)PIC1 (25
ns)PIC2 (25
ns)US1 (25
ns)US2 (25
ns)HL-LHC (25 ns)
HL-LHC (50 ns)
M 2808 2808 1374 2592 2748 2595 2748 2808 1404Nb 1.15 1.8 1.6 1.38 1.38 1.9 2.2 2.2 3.5
Broadband (M*Nb2) 1.06 2.59 1 1.4 1.49 2.66 3.78 3.86 4.89
Narrow band (M*Nb)2 2.16 5.29 1 2.65 2.98 5.03 7.56 7.9 5
*Narrow band is a worst case scenario assuming that the resonance stands exactly at a multiple of 40 MHz
Increase in heat load from intensity increase and bunch length decrease
Increase in heat load from intensity increase and bunch length decrease to 1 ns (table)
Factor from situation before LS1
Nominal (25 ns)
ultimate (25 ns)
Before LS1 (50
ns)PIC1 (25
ns)PIC2 (25
ns)US1 (25
ns)US2 (25
ns)HL-LHC (25 ns)
HL-LHC (50 ns)
M 2808 2808 1374 2592 2748 2595 2748 2808 1404Nb 1.15 1.8 1.6 1.38 1.38 1.9 2.2 2.2 3.5
Broadband (M*Nb2) 1.48 3.62 1 1.96 2.08 3.73 5.29 5.41 6.85
Narrow band (M*Nb)2 3.02 7.40 1 3.71 4.17 7.04 10.59 11.05 6.99
*Narrow band is a worst case scenario assuming that the resonance stands exactly at a multiple of 40 MHz
Agenda
• Beam spectra for 800 MHz?• Scaling to PIC1, PIC2, US1, US2• Potential issues for hardware (difficult to
predict)
Elements to be considered• Beam screens
– arcs, standalones, inner triplets• Collimators
– TDI, single beam collimators, TCDQ• Kickers
– MKI• Diagnostics
– BSRT, BGV, stripline and button BPMs, wire scanners• RF cavities• Interconnects, warm pipe, experimental chambers, Y-chambers• Septa
Current beam screens• Expected from theory, accounting for the weld on the side (+44%, see PhD of
Andrea Mostacci and Carlo Zannini) and magnetoresistance (for instance in PhD of Nicolas Mounet, pessimistic for quadrupoles), accounting for factor 2 in addition (could be worst case for 2 beams in same aperture, pessimistic). Note: optics aperture chosen instead of mechanical aperture (more pessimistic).
For the arcs, cooling power is 200 W per half cell (i.e. 3800 mW/m). Is that enough margin for synchrotron radiation and electron cloud?
Could also be limiting for standalones and triplets (if cooling power is 250 W 8300 mW/m).
Power loss for 2 beams in mW/m
Nominal (25 ns)
ultimate (25 ns)
Before LS1
(50 ns)PIC1
(25 ns)PIC2
(25 ns)US1
(25 ns)US2
(25 ns)HL-LHC (25 ns)
HL-LHC (50 ns)
M 2808 2808 1374 2592 2748 2595 2748 2808 1404Nb 1.15 1.8 1.6 1.38 1.38 1.9 2.2 2.2 3.5
Half gap 18.4 mm (arc) 290 509 165 386 409 733 1040 1060 1350
Half gap 24 mm(inner triplets Q2 and Q3) 445 781 253 592 628 1120 1590 1630 2060
Half gap 18.95 mm (inner triplets Q1) 563 989 321 750 795 1420 2020 2060 2610
New triplet beam screens• Expected from round pipe theory as in talk of Nicolas Mounet on new triplets
(01/07/13), accounting for the weld on the side (+10% to 25% estimated by Carlo Zannini depending on the position of the weld) and magnetoresistance (pessimistic for quadrupoles), accounting for factor 2 in addition (could be worst case for 2 beams in same aperture, pessimistic), not yet accounting for the change of impedance linked to the transverse position inside the triplets (currently studied by Carlo and GIovanni).
Power loss for 2 beams in mW/m
Nominal (25 ns)
ultimate (25 ns)
Before LS1
(50 ns)PIC1
(25 ns)PIC2
(25 ns)US1
(25 ns)US2
(25 ns)HL-LHC (25 ns)
HL-LHC (50 ns)
M 2808 2808 1374 2592 2748 2595 2748 2808 1404Nb 1.15 1.8 1.6 1.38 1.38 1.9 2.2 2.2 3.5
Half gap 49 mm 189 332 108 252 267 478 678 693 877
Half gap 59 mm 157 276 90 209 222 397 563 575 728
Beneficial effect of new triplets beam screens (factor of ~3 for the given parameters) as already stated by Nicolas
Elements to be considered• Beam screens
– arcs, standalones, inner triplets• Collimators
– TDI, single beam collimators, TCTP, TCDQ• Kickers
– MKI• Diagnostics
– BSRT, BGV, stripline and button BPMs, wire scanners• RF cavities• Interconnects, warm pipe, experimental chambers, Y-chambers• Septa
Single beam collimator: worst case is the TCP
• worst case is the TCP (less conductive, closest to beam)• CFC resistivity: 8 microOhm.m (measured at 5 microOhm.m)
Power loss for 1 beams in W
Nominal (25 ns)
ultimate (25 ns)
Before LS1
(50 ns)PIC1
(25 ns)PIC2
(25 ns)US1
(25 ns)US2
(25 ns)HL-LHC (25 ns)
HL-LHC (50 ns)
M 2808 2808 1374 2592 2748 2595 2748 2808 1404Nb 1.15 1.8 1.6 1.38 1.38 1.9 2.2 2.2 3.5
Half gap 18.4 mm (arc) 96 234 64 127 134 241 342 350 443
These collimators are designed to withstand 7 kW. Is there enough margin left for particle impact?
TDI collimator• TDI (results of Nicolas for resistive wall of ceramic blocks)
Power loss in W Nominal 25 ns (2808*1.15, 1 ns, 7 TeV)
Before LS150 ns (1374*[email protected] ns, 4 TeV)
HL-LHC25 ns(2808*2.2)
HL-LHC50 ns(1404*3.5e11)
TDI without coating (55 mm half gap) -> collision param.
60 67 219 283
TDI with 1 micron copper coating (55 mm half gap)-> collision param.
2.9 3.2 10.5 13.6
TDI without coating (3.8 mm half gap) -> injection param.
640 705 2330 2985
TDI with 1 micron copper coating (3.8 mm half gap)-> injection param.
32 35 116 150
Not relevant (as TCTP), as needs to be completely refurbished (cut in 5 different collimators with different materials and new cooling).Current cooling for TCP in the range of the needed cooling
Elements to be considered• Beam screens
– arcs, standalones, inner triplets• Collimators
– TDI, single beam collimators, TCTP, TCDQ• Kickers
– MKI• Diagnostics
– BSRT, BGV, stripline and button BPMs, wire scanners• RF cavities• Interconnects, warm pipe, experimental chambers, Y-chambers• Septa
Injection kickers• Data from Hugo Day et al obtained by measurements on revised MKIs, to
be installed during LS1• Worst case bunch distribution between Gaussian and parabolic chosen
Power loss in W Nominal 25 ns (2808*1.15, 1 ns, 7 TeV)
Before LS150 ns (1380*[email protected] ns, 4 TeV)
HL-LHC25 ns(2808*2.2)
HL-LHC50 ns(1404*3.5e11)
MKI (24 screen conductors) 34-52 W/m 20-34 W/m 124-191 W/m 151-240 W/m
MKI8D (15 screen conductors and non-conform)
- 161 W/m - -
No detailed update from TE/ABT for PIC/US parameters, other high priority activities for the moment. Will come soon , but should be in line with the general scaling: PIC1 39-67 W/m
PIC2 41-71 W/m US1 75-126 W/m US2 106-180 W/m ( could be limiting with the upgraded hardware)
Elements to be considered• Beam screens
– arcs, standalones, inner triplets• Collimators
– TDI, single beam collimators, TCTP, TCDQ• Kickers
– MKI• Diagnostics
– BSRT, BGV, stripline and button BPMs, wire scanners• RF cavities• Interconnects, warm pipe, experimental chambers, Y-chambers• Septa
Example of striplinePower loss in W Nominal
25 ns (2808*1.15, 1 ns, 7 TeV)
Before LS150 ns (1374*[email protected] ns, 4 TeV)
HL-LHC25 ns(2808*2.2)
HL-LHC50 ns(1404*3.5e11)
Stripline (63 mm) 15 10 55 70
Are these heat loads an issue for the stripline?Losses are mostly in the cables possibility to use attenuators , and need to change electronics. Signal can be perturbed with so much attenuation (loss of bandwidth).Already checked for 3.5e11 OK for the peak power
Wire scanner could be an issue due to the cavity.
BTV ok thanks to the shielding chamber.
WCM same issue as stripline
Current transformers new design under way (temperature probes installed but never used)
New BSRT design under fabrication (without ferrites)
Summary• Beneficial effect of studied flat bunches on heating is not evident. However, important
to point out that the MD in 2012 showed beneficial effect for several devices.
• Upgrades of electronics for instrumentation would be needed, and the MKI upgrade foreseen for LS1 may not be enough for US1 and especially US2.
• Current TDI is already not enough for current power loss. Needs upgrade of design and especially of the cooling.
• Impedance will take a significant portion of the cooling power for the arcs and the triplets (10 to 30%). Is there enough margin for the other contributions (ecloud and synchrotron radiation?)
• Effect of “real” filling scheme and bunch length for 25 ns could also be checked
General consideration on power loss for HL-LHC parameters (1/3)
• intensity per bunch increase Ploss Nb
2
for 25 ns: 1.15e11p/b to 2.2e11 p/b leads to a factor 3.7 for 50 ns: 1.6e11 p/b to 3.5e11 p/b leads to a factor 4.8
• Number of bunches 2808 for 25 ns and 1404 for 50 ns for broadband impedance, what matters is M*Nb
2
for narrow band impedance, what matters is (M*Nb)2
Factor from situation before LS1
Nominal 25 ns (2808*1.15)
Before LS150 ns (1374*1.6e11)
HL-LHC25 ns(2808*2.2e11)
HL-LHC50 ns(1404*3.5e11)
Broadband (M*Nb
2)*1.05 1 *3.9 *4.9
Narrow band (M*Nb)2
*2.1 1 *7.9 *5
Significant increase of power loss expected for HL-LHC intensities
1
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General consideration on power loss for HL-LHC parameters (3/3)
• intensity per bunch increaseFactor from situation before LS1
Nominal 25 ns (2808*1.15)
Before LS150 ns (1374*1.6e11)
HL-LHC25 ns(2808*2.2e11)
HL-LHC50 ns(1404*3.5e11)
Broadband (M*Nb
2)*1.05 1 *3.9 *4.9
Narrow band (M*Nb)2
*2.1 1 *7.9 *5
Significant increase of power loss expected for HL-LHC parameters (factor 5 to 7)
• Accounting for decrease of bunch length (*1.4)Factor from situation before LS1
Nominal 25 ns (2808*1.15, 1ns)
Before LS150 ns (1374*1.6e11, 1.25 ns)
HL-LHC25 ns(2808*2.2e11, 1ns)
HL-LHC50 ns(1404*3.5e11, 1ns)
Broadband (M*Nb
2)*1.5 1 *5.4 *6.9
Narrow band (M*Nb)2
*2.9 + ? 1 *11 (?) + ? *5 (?) + ?