Download - ENERGY DEPOSITION IN HYBRID NbTi/Nb 3 Sn TRIPLET CONFIGURATIONS OF THE LHC PHASE I UPGRADE
ENERGY DEPOSITION IN HYBRID
NbTi/Nb3Sn TRIPLET CONFIGURATIONS
OF THE LHC PHASE I UPGRADE
Fermilab Accelerator Physics Center
Nikolai Mokhov, Fermilab
CERNMarch 31 – April 2, 2008
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov2
OUTLINE
•Introduction
•Three Upgrade Configurations Studied
•MARS15 IR and Quad Models
•Power Density Maps
•Peaks w.r.t. Design Limits
•Heat Loads
•Summary
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov3
INTRODUCTION
JIRS project of the LARP aims at investigation of potential of replacing one (on each side of IP) of the NbTi quadrupoles with a Nb3Sn one in the LHC Phase I upgrade of high-luminosity IRs. Based on realistic energy deposition calculations, we are trying to derive operational margins for the quads in various configurations. Preliminary results are presented here.
Simulations are done with MARS15 (2008), and DPMJET-3 as an event generator for 7x7 TeV pp-collisions at 2.5x1034 cm-2 s-1, using low-betamax and symmetric optics from John Johnstone.
IP5 (R) is considered, with a full crossing angle of 450 rad, segmented absorbers SS or W (possibly) cooled at LN2-temperature, as proposed in our paper PRSTAB, 9, 10001 (2006) and Proc. WAMDO06 Workshop, CARE-Conf-06-049-HHH, p. 80 (2006).
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov4
1. LOW-BETAMAX OPTICS: LBM-1 in MARS15
Q1: 90-mm NbTi, 167.2 T/m, L=7.06 m
Q2: 130-mm NbTi, 121.4 T/m, L=7.787m x 2
Q3: 110-mm Nb3Sn, 176.2 T/m, L=3m x 2
TAS aperture:(a) 42 mm(b) 55 mm3-mm segment
absorbers:W in Q1, SS in Q2, no in Q3
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov5
2. LOW-BETAMAX OPTICS: LBM-2 in MARS15
Q1: 90-mm Nb3Sn, 206.1 T/m, L=5.65 m
Q2: 130-mm NbTi, 121.1 T/m, L=7.787m x 2
Q3: 130-mm NbTi, 121.1 T/m, L=8.711 m
TAS aperture: 55 mm3-mm segment
absorbers:SS in Q1, Q2 & Q3
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov6
3. SYMMETRIC OPTICS: SYM-1 in MARS15
Q1: 90-mm Nb3Sn, 203.8 T/m, L=2.75m x 2
Q2: 130-mm NbTi, 121.9 T/m, L=7.8m x 2
Q3: 130-mm NbTi, 121.9 T/m, L=9.2 m
TAS aperture: 55 mm3-mm segment
absorbers:SS in Q1, Q2 & Q3
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90, 110 and 130-mm Quad Design
OPERA-calculated 2-D magnetic maps:200, 180 and 125 T/m, x = y = 2 mm
By Vadim Kashikhin
90-mm
110-mm
130-mm
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov8
MARS15 IMPLEMENTATION
90-mm Nb3Sn 130-mm NbTi
Same scale
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov9
Beam screens, segment absorbers, cold bore, kapton,LHE, coils, collar, yoke and cryostat in MARS15
Same scale90-mm Nb3Sn 130-mm NbTi
Cryostat: thermal shield and vessel (R=457 mm)
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov10
CONSISTENCY CHECKS
Example: LBM-2
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Particle Tracks for 1 pp-event at 7x7 TeV
Example: SYM-1
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POWER DENSITY MAP: LBM-1
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Power Density Profiles at Longitudinal Peaks: LBM-1
Quad endsQ1 non-IP
Q2b non-IP
Q3a IP
Q3b IP
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POWER DENSITY MAP: LBM-2
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POWER DENSITY MAP: SYM-1
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Power Density Profiles at Longitudinal Peaks: SYM-1
Q1b non-IP end Q2b non-IP end
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov17
QUENCH LIMITS & DESIGN GOAL
Quench Limit
mW/g mW/cm3 mW/g mW/cm3
NbTi 1.6 11.2 0.53 3.71
Nb3Sn 5 34 1.66 11.3
Design Goal
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov18
Low-betamax-1: Peak Power Density in Cable-1 vs z
LBM-1: 42-mm TAS LBM-1: 55-mm TAS
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LBM-2 & SYM-1: Peak Power Density in Cable-1 vs z
LBM-2 SYM-155-mm aperture TAS
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Peak Power Density wrt Design Limits
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HEAT LOADS
At L=2.5x1034 cm-2 s-1, pp-interactions result in power of 2.24 kW per beam carried out from IP1 and IP5. About 1/3 of this power is deposited in the TAS and triplet.
Power dissipation in the TAS scales with the luminosity and decreases with aperture increase thus giving rise to the power deposited in cold components.
TAS: 455W at 34mm, 360W at 42mm, and 283W at 55mm.
Heat loads in low-betamax (LBM-2) optics (Watts):
109 (Q1), 20 (MCBX), 74 (Q2a), 84 (Q2b), 25 (MQSX), 7 (TASB), 80 (Q3), 11 (MCBXA), 27 (DFBX), 17 (vessel).
JIRS meetings, CERN, Mar. 31 – Apr. 2, 2008 Energy Deposition in Hybrid IR Phase I Upgrade - N. Mokhov22
HEAT LOAD BALANCE (Watts)
LBM-1 LBM-2 SYM-1
LHe (bore, SC, collar, yoke)
264 306 292
“LN2” (beam screen and segm. absorber)
173 101 104
Room T (vessel) 20 20 23
Total 457 427 419
Grand total(TAS included)
740 710 702
55-mm TAS Q1 to MCBXA ~ 40 m
~6.6 W/m
LHe+”LN2” ~11 W/m
~7.7 W/m
LHe+”LN2” ~10 W/m
~7.3 W/m
LHe+”LN2” ~9.9 W/m
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SUMMARY (1)
1. There are always four pronounced peaks in
longitudinal distributions of maximum power density in the first SC cable (averaged over the cable area at the azimuthal maxima): close to Q1 non-IP end, Q2a IP end, Q2b non-IP end and Q3 IP end (see also LHC PR 633, 2003).
2. For the configurations considered all the peaks are safely below the design limits (for 55-mm TAS).
3. Increasing TAS aperture from 42 to 55mm, increases first peak by 10% and heat load to the cold components by 75 W.
4. 3-mm tungsten absorbers in Q1 provides reduction of peaks by a factor of about 3 and 2 in Q1 and Q2, respectively, compared to the stainless steel ones.
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SUMMARY (2)
5. Peak in Q3 is practically insensitive to the
configuration.
6. Compared to the nominal case, dynamic heat loads to theSC quads are certainly higher at 2.5x1034 cm-2 s-1 and enlarged TAS aperture, but – because of larger quad apertures and use of absorbers - seem to be manageable, especially with high-Z absorbers cooled at LN2.
7. Using Nb3Sn for Q1 or Q3 instead of NbTi substantially increases operational margins, frees space for instrumentation between quads, and provides verification of this new technology for Phase II.
8. Thanks to J. Johnstone for optics, V. Kashikhin for quad geometry and magnetic field maps, I. Rakhno & S. Striganov for enhancement of analysis tools, and A. Zlobin for coordination.