“Overview of magnetic measurements at CERN” [email protected]1/38 MAGNETIC MEASUREMENT SECTION cern.ch/mm “Overview of magnetic measurements at CERN” [email protected]1/35 MAGNETIC MEASUREMENT SECTION cern.ch/mm Contents Part 1 – Generality and infrastructure Team news, new test hall, workflow improvements Part 2 – Accelerator projects HILUMI, LIU … Part 3 – Sensors and instrumentation Rotating coil systems, mappers and other R&D Overview of Magnetic Measurements at CERN D. Akhmedyanov, M. Amodeo, P. Arpaia, J. Bardanca, A. Beaumont, R. Beltron Mercadillo, M. Bonora, N. Bruti, M. Buzio, E. M .Cervera, A. Chiuchiolo, E.J. Cho, R. Chritin, M. Dantas, G. Deferne, V. Di Capua, O. Dunkel, L. Fiscarelli, J. Garcia Perez, D. Giloteaux, G. Golluccio, X. Gontero, C. Grech, F. Greiner, S. Gutzeit, R. Jaeger, A. Junge, K. Kaismoune, P. Kosek, M. Liebsch, A. J. Malibiran, K. Monneron, Hans G. Mueller, A. Parrella, M. Pentella, C. Petrone, I. Pschorn, P. T. Rogacki, S. Russenschuck, V. Sinatra, S. Sorti, E. Tournaki, J. Vella Wallbank, V. Velonas, M. Verwiel, A. Windischhofer, T. Zickler
Part 1 – Generality and infrastructureTeam news, new test hall, workflow improvements
Part 2 – Accelerator projectsHILUMI, LIU …
Part 3 – Sensors and instrumentationRotating coil systems, mappers and other R&D
Overviewof Magnetic Measurements at CERN
D. Akhmedyanov, M. Amodeo, P. Arpaia, J. Bardanca, A. Beaumont, R. Beltron Mercadillo, M. Bonora,N. Bruti, M. Buzio, E. M .Cervera, A. Chiuchiolo, E.J. Cho, R. Chritin, M. Dantas, G. Deferne, V. Di Capua,
O. Dunkel, L. Fiscarelli, J. Garcia Perez, D. Giloteaux, G. Golluccio, X. Gontero, C. Grech, F. Greiner,S. Gutzeit, R. Jaeger, A. Junge, K. Kaismoune, P. Kosek, M. Liebsch, A. J. Malibiran, K. Monneron,Hans G. Mueller, A. Parrella, M. Pentella, C. Petrone, I. Pschorn, P. T. Rogacki, S. Russenschuck,
V. Sinatra, S. Sorti, E. Tournaki, J. Vella Wallbank, V. Velonas, M. Verwiel, A. Windischhofer, T. Zickler
2 1.5 T, 80 mm gap reference dipolesNMR mapped for flip-coil area calibration
2 9.5 T/m, 125 mm gap reference quadrupolesfor rotating coil radius calibration
reference solenoid
15+ rotating coil systems8 to 300 mm, 150 mm to 2.5 m length
3D LEICA laser trackersfor axis fiducialization
1D/3D Hall-probe and fluxmeter field mappers
• Finished in Dec 2017 at the cost of 7.5 MCHF (well on time and wthin budget)• 1600 m2 on two floors, 17 independent test benches, 2 water cooling circuits• 40-ton crane (adequate for all beam-line magnets in the complex)• Thermal stabilization 212.0 °C
New test hall (bldg. 311)• Separated high-accuracy test hall with high mechanical/thermal stability (210.5 °C)• Optimized AC airflow for vibrating wire systems• 5 T crane
Low-resonant frequencygranite benches
Vibrating/translating stretched wire systems(reference for integral field strength and axis)
• Highest-priority project:- replace rad-damaged IR quads- 10 luminosity = +25% discovery range
• 100 magnets of 11 types to be measured before end 2023
• Main challenge: first operational accelerator-quality Nb3Sn magnets ever- XX, 60 mm, 10 m long 11 T dipoles- XX, XX mm, X m long X T/m quads
• Magnetic measurement challenges:- XX warm rotating coil systems to be operated on manufacturer’s premises- 130 mm anticryostats and 10 m long rotating coil systems- longitudinal alignment IR triplets
• 24+6, 60 mm 10 m, 11 T bending dipoles• install in 2020 at IP X and X to make room for new collimators
11 T dipoles
LBH_A LBH_BBy-pass cryostat
• “Clean” training curve• Single quench to nominal current• Even at 4.5 K reaching almost ultimate current
(good temperature margin for nominal operation)• 94% of conductor short sample reached @ 4.5 K• Better training in first cool down than all models• Coil limit @ 4.5 K = 300 A > best model magnet 0 2 4 6 8
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• Magnetic measurements done with legacy LHC system (15 m ceramic shafts)• Compared to NbTi dipoles: large harmonics hysteresis, flux jumps
• Aim: increase intensity and enable injector chain to sustain high-luminosity LHC operation• More than 120 new or refurbished magnets to test until 2020 (80 done to date)• Mostly regular tests with existing equipment
LHC Injectors Upgrade Project
orbit corrector for the new transfer lines Linac4 → PSB “Y-shaped” switching dipole for the PSB extraction
new PS extraction bumper with extra loopsfor passive sextupole compensation New main PSB insertion and extraction dipole
quadrupole for the PSB extraction line to PS
quadrupole for the new transfer lines Linac4 → PSB
• Three major alternatives being put forward for future colliders: HE-LHC (27 TeV with 16 T dipoles in the LHC tunnel), FCC-hh (100 TeV, new 100 km tunnel with 16 T magnets) and FCC-ee (365 GeV, 100 km tunnel with 57 mT dipoles)
• Only few magnets and device prototypes tested so far• Example: SuShi, a passive MgB2 shield for 3T FCC-hh septa
• EuCARD-2 case study: 5 T Feather M2 dipole with 10 kA Roebel ReBCO cable• Fixed-coil magnetic measurements in a vertical cryostat (not adapted to rotating coils)• Good results thanks to cross-calibration of coils and Hall probes
HTS magnets
C. Petrone et al., Measurement and analysis of the dynamic effects in a HTS dipole magnet, EUCAS 17
1500 1550 1600 1650 1700-0.5
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3 5 200 mm long radial coils
3 AREPOC LHP-NP Hall probes
Uncalibrated Hall probes20% gain uncertainty
Uncorrected integrator driftup to 0.5% over 300 s
B during fast ramp usedto calibrate Hall probe gain
Constant Hall probe signal estimation and correction
• 26 multiplets (170 magnets) + 24 bending dipoles, super-ferric with supercritical He cooling• Very large warm bores: 192 (multiplets), 380 180 mm (dipoles)• Dedicated test area with 3 reconfigurable benches being finalized in b. 181• First short multiplet being prepared for tests → see Pawel Kosek’s talk
• XXX new rotating coils (being) built for HL-LHC and other projects using new modular design• 2 carbon fiber half-cylinders with radial coil PCB (max. individual length 1.2 m)
Rotating coils
non-magnetic retroreflector standard Mobile Rotating Unit
radialPCB coils
330 mm FAIR multiple coil – our largest ! Credit: G. Golluccio
• 8 new systems (being) built (of which 6 with vibrating wire functionality) • most old FNAL hardware replaced, software based on FFMM C++ framework (see G. Deferne IMMW19)
• Reproducibility from systematic cross-calibration campaign: BdL 1.64 units, GdL 2.45 units, roll angle 0.035 mrad, axis 0.041 mm
• R&D ongoing: harmonic and pulsed-mode measurements
• BHZ10 switching dipole issues: open-loop hysteresis (2GeV, 1.4GeV), L/R asymmetry• Requirement: high precision absolute field integral + transversal uniformity • Solution: a combination of curved fixed coil + curved “stretched” wire
Curved stretched wire
reversible G10 support for L/R beam paths
repurposed old SSW stages(can be switched back to wire operation)
one end pivotingother end simply
supported
• two fixed coils (symmetric w.r.t. wire) for high resolution dynamic measurements• single-turn translating stretched wire inserted in a groove for precise DC transverse profile,
remanent field and absolute calibration of effective coil width • discrete Hall probes/PCB coil pairs to measure local eddy current effects
• New translating PCB fluxmeter for transverse and longitudinal uniformity of large FAIR dipoles• Central coil calibrated by NMR at the center; others cross-calibrated by shifting the array
• Under construction: general-purpose, 3-axis mapper with <manufacturer> translation stages • Full calibration of 3D HE444 Hall sensor vs T, B and ongoing (8 mrad orthogonality, 0.3% non-linearity)
• Replace traditional mapping on a 3D grid with boundary mapping + BEM post-processing:
3D mapping system
3 m 1.5 m 1.5 m stroke
(XX m accuracy @ XX mm/s)
Green’s function
𝐁 = 𝜇0𝛻 නΓ
Φm 𝐫′ 𝐧 ⋅ 𝛻𝐺 𝐫, 𝐫′ d𝐫′ −නΓ
𝐺 𝐫, 𝐫′ 𝐧 ⋅ 𝛻Φm 𝐫′ d𝐫′
Hall probe
measured Neumann boundary dataBEM-computed Dirichlet boundary data
B-train systems• 4/6 new systems in operation with beam for 27 aggregated
months in 2018 (PS, PSB, LEIR, ELENA)
• Metrological performance matching or exceeding old systemsrepeatability ~0.05 G, abs. uncertainty 1~2 G, integrator drift 0.02 G/s (PS)
• No critical reliability issues identified(sporadic integrator freeze in 2017, fixed with 64-bit driver update)
• Consolidation goals met- obsolete VME FEC in PS, PSB, LEIR and AD can be phased out during LS2- LEIR operation demonstrated with new external flux loop + FMR field marker
• Planned work during LS2- simulated B-train: hardware already tested in the PS, software to be adaptated for the AD- completion and test of the new system for the 2 GeV PSB- commissioning of the new SPS system (NB operation with old one still possible after LS2)- integrator error correction improvements, predicted field facility, diagnostics LEIR tomoscope (charge density at extraction)
Old B-train New B-train
LEIR bending dipole
PS FIRESTORM B-train via White Rabbit
Correlation OP/SPARE systems on a LHCION cycle
tim
ebunch length
RMS difference 0.6 G
offset 0.4 G
Credit: M. Amodeo, A. Beaumont, V. Di Capua, D. Giloteaux, C. Grech,
• WR: a CERN-developed, Ethernet-based IEEE standard used in B-trains for digital distribution of the measured field across several km with ns accuracy and ~20 us latency, up to 1 M data frames/s (theoretical)
• WR Sniffer: new tool for simultaneous acquisition of multiple full-speed data streams
White Rabbit Sniffer
• NI cRIO-based FPGA firmware• seamless integration with standard DAQ/multifunction card on the
same time base for complex measurement and control applications
• Current functionality: datastream visualization and storage• In development: real-time post processing for advanced diagnostics
• Derivative of B-train integrator based on CERN Open Hardware FPGA Mezzanine Cards (FMC)• Wide input ranges, self-calibration and offset correction facilities• Adapted for rotating- and fixed-coil measurements• Remote configuration, diagnostics and data retrieval possible via FESA C++ control framework• First prototypes under test
New FMC-Fast Digital Integrator
I/O
FMC integrator FMC integrator
4-lane PCIeFPGA: IO manager,
calibration and integration logic
Gain 0.1 to 500, input range 20 mV to 100 V
LVDS
20 bit SAR ADC LTC 2378Ratiometric correction of coil loading error
best-fit correction of ADC non-linearity
Overall block layoutCredit: D. Giloteaux, T. Rajkumar
