Introduction to PACMAN Work Package 2 Magnetic Measurements

1. Introduction to PACMAN Work Package 2Magnetic Measurements Marco Buzio, Stephan Russenschuck (CERN, TE-MSC)

2. Overview of WP 2 • Main goals: • develop instruments and methods to measure the position of the magnetic axis of quadrupole magnets within an absolute uncertainty of 10~20 m and a resolution of the order of nanometers • develop instruments and methods to measure the field strength and quality (polarity, direction, harmonic content) of multipole magnets inside gaps as small as 4 mm • Additional constraints: • integration with other equipment on the test stand • scalability to very large industrial production (issues: automation, robustness, cost, speed)

3. ESR 2.1: Stretched wire systems for the magnetic measurements of small-aperture magnets

4. ESR 2.1: Stretched wire systems for the magnetic measurements of small-aperture magnets • Status: • Well-established single translating wire technology for standard measurements of multipole magnets with 20 mm: absolute metrological reference for integrated field strength, direction and magnetic axis of LHC MB/MQ • Ongoing R&D on oscillating wire technology for magnetic center localization and integrated field quality (harmonics) • Potentially able to provide Bn(s) profiles • 1 prototype system available, already used on solenoids, CLIC and Linac4 quads • main drawback: slow (Fourier analysis at each (x,y) position  long acquisition needed for good resolution in frequency)  measurement of steady-state fields only • the only instrumentthat looks scalable down to 4 mm

5. ESR 2.1: Stretched wire systems for the magnetic measurement of small-aperture magnets • Goal: development of an oscillating wire system integrated on the test stand and compatible with mechanical and RF alignment methods • R&D directions: • design and qualification of sensors and components: wire material, optocouplers, inductive sensors, linear translation stages, electronic acquisition systems • metrological system characterization: non-linear effects, non-ideal wire geometry, magnetic forces on the wire, influence of ambient fields and vibrations, influence of wire sag and tension, influence and reconstruction of longitudinal field profile, resistive and inductive effects on wire voltage, absolute and relative calibration … • axis transfer: the wire is located, on average, on the magnetic axis  a survey (by optical or mechanical means) must relate the coordinates of the wire ends to the test stand reference system. Main metrological issue: identification and elimination of systematic and random errors (can we use the existing CMM ?) • electronic acquisition: advanced ADC and signal processing, lock-in functionality, automated fault detection, integration within existing equipment (Fast Digital Integrators, C++ Flexible Framework for Magnetic Measurements)

6. ESR 2.2: Printed Circuit Board technology for small-diameter field probes Prototype 7.8 mm rotating coil

7. ESR 2.2: Printed Circuit Board technology for small-diameter field probes • Status: • Well-established rotating coil technology for the measurement of local and integral field strength, direction, axis and harmonics in multipole magnets with >20mm. Reference method for field quality. •  20 mm system developed for Linac4 and used for DBQ prototypes. Systematic errors e.g. 20 units of b3 due to poor coil geometry (solution using numerical coil bucking under test) •  8 mm protoype PCB coils developed for MQ protos. Poor mechanics  difficult calibration (ongoing effort) • Main advantages: fast, inherently accurate field harmonics

8. ESR 2.2: Printed Circuit Board technology for small-diameter field probes • Goal: development of a rotating coil system (single scanning coil and/or coil train) integrated on the test stand and aimed mainly at field strength and quality series acceptance tests • R&D directions: • improvement of PCB coil head: track density, layer referencing and alignment, mechanical stiffness, alignment and stability of ball bearings, scaling above and below 8 mm • electronic acquisition systems: correction of side effects of high resistance load coils • metrological characterization: absolute and relative calibration/ cross calibration w.r.t. wires, impact of ambient conditions (mechanical and electrical noise, temperature) … • referencing of rotating axis for magnetic axis fiducialization • measurement of time-varying magnetic axis drift, vibrations, etc. in fixed-coil mode

9. Network-wide training activities – workshops & conferences

10. Network-wide training activities – workshops & conferences

11. Network-wide training activities – workshops & conferences

12. WP2 PACMAN Partners ELTOS, Arezzo, IT • Design and manufacture of innovative multi-layer rigid PCBs for industrial, medical, communications, computing, defense, aerospace, automotive markets worldwide • Founded 1980, 100 employees of which30% engineers, 12 M€/year turnover • Established as a successful commercial partner of CERN on prize-winning large-size PCBs for LHCb and unique fluxmeters for the MedAustron collaboration Possible R&D topics for ESR 2.2: - tools, materials and techniques for search coils on PCBs- high density, high precision tracks for large fluxmeters- high precision multi-layer PCB alignment and stacking- mechanical improvement of rotating coil heads and fluxmeter assemblies- quality assurance, long term dimensional stability SEEP lequerre’stALK Data and pictures courtesy of ELTOS

13. WP2 PACMAN Partners METROLAB, Geneve, CH • Unique NMR PT2025 teslameter used worldwide as the metrological reference for field strength calibration and ultra-precise field mapping • Leading provider of fluxmeters for mapping accelerator magnets… • … and a family of 3-axis Hall/fluxgate magnetometers for measurements in industrial, research, medical imaging and environmental applications • Founded in 1985, 10 employees of which 5 scientists/engineers, ~5MCHF turnover • Strategic partners of CERN in several technology transfer initiatives, from the forefathers of PT2025 to PDI and FDI digital integrators Possible R&D topics for ESR 2.1- Cross-calibration of wire systems with NMR/Hall probes- Integration of low-level, long-duration voltage signals- Characterization of next-generation NMR teslameters for real-time magnet control applications Data and pictures courtesy of METROLAB

14. WP2 PACMAN Partners Sigma Phi, Vannes, FR • Leader in the design and manufacture of magnets , power converters and other components for industry, high energy physics and medical accelerators • Founded in 1981, 50 employees of which 22 scientists and engineers, … turnover • Extensive facilities for in-house magnetic testing • Possible R&D topics for ESR 2.1 and 2.2:- fine-tuning magnetic measurements to provide useful feedback to production- critical aspects of the use of stretched wire and rotating coil systems in industrial settings: robustness and user-friendliness of the control software, frequencyof recalibration- practical measurement validation and magnet acceptance criteria Data and pictures courtesy of SigmaPhi

15. WP2 PACMAN Partners Università del Sannio,Benevento, IT • Multi-disciplinary academic pole serving a large territory in Campania and Basilicata • Established in 1998, 8000 students, • Very active international research and European collaboration center (PTB, NIST, INRIM, SEMETRO, IMEKO, IEEE IM) • Long-standing R&D collaboration with CERN on magnetic measurements, electric current measurements and other electronic instrumentation:- 15+ Master- and PhD- level graduates- Development of key infrastructure such as the C++ Flexible Framework for Magnetic Measurements and the Fast Digital Integrators- Essential contributions to the development of rotating coil systems and stretched wire techniques Data and pictures courtesy of Universita’ del Sannio