S. Russenschuck, CLIC-Workshop, WP2-Pacman, R&D projects on rotating coil probe and stretched wire techniques for CLIC / PACMAN Stephan Russenschuck for the CERN magnet (measurement) -team CLIC workshop

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Rotating Coil Measurements Tangential coil Radial flux Radial coil Tangential flux

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Series Measurements of the LHC Magnets

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Standardized Equipment – Motor Drive Unit Drive unit for measurements in horizontal (rt) and vertical (cryogenic temp.) position

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Standardized Equipment – Rotating Coil Shafts Shaft for measurements in a vertical cryostat Shaft R=45 mm, coil length: 130 mm Shaft R=30 mm, coil length: 1200 mm

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Flexible Framework for Magnetic Measurements

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Rotating Coil Measurements

S. Russenschuck, CLIC-Workshop, WP2-Pacman, The Riemann Lebesque Lemma 8 The Fourier coefficients tend to zero as n goes to infinity (Riemann Lebesque) and they must scale according to the Cauchy theorem for bounded functions Simulations !

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Spread and Noise Floor in Measurements Compensated Noncompensated Radial axes displacement Torsional deformations Blind eye?

S. Russenschuck, CLIC-Workshop, WP2-Pacman,  Challenges – Sensitivity and tolerances on small shafts – Bucking ratio – Vibrations and noise – Calibration – Connection  PACMAN R&D efforts – PCB technology for coils – Rapid prototyping for shaft – Micro-connectors – MRU-II (smaller, smoother) – In-situ calibration – “Intelligent” post-processing

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Architecture Stretched Wire Experimental Setup

S. Russenschuck, CLIC-Workshop, WP2-Pacman, The Single Stretched Wire Method

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Measurement system design Oscillating wireVibrating wire Map of Second Wire Resonance Wire Excitation Frequencies Stretched wire

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solenoid Center and Axis Force distribution requires vibration at the second resonance

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solenoid Center and Axis: Transversal Field Profiles Left: Perfectly aligned. Right: With swing Therefore: Switch to first resonance, and align (move) the magnet, not the stages

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solenoid Center: Oscillation Amplitudes Modulus At x sensor At y sensor For small displacements from the center, the B y component is a linear function in x

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Linear Regression in the Line Search Procedure

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Vibrating wire for magnetic axis Solenoid magnet Map of Second Wire Resonance Before alignmentAfter alignment

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Vibrating wire for magnetic axis Solenoid magnet Map of Second Wire Resonance (on 2 mm radius)

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solving Boundary Value Problems I 1. Governing equation in the air domain 2. Chose a suitable coordinate system, make a guess, look it up in a book, use the method of separation, that is, find orthogonal and complete eigenfunctions. Coefficients are not know at this stage 3. Incorporate a bit of knowledge, rename, and calculate field components

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solving Boundary Value Problems II 4. Measure or calculate the field (flux) on a reference radius and perform a discrete Fourier analysis (develop into the eigenfunctions). Coefficients are known here. 5: Compare the known and unknown coefficients 6. Put this into the original solution for the entire air domain

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solving the Boundary Value Problem Take any 2  periodic function and develop according to For the oscillating wire technique: Use the oscillating amplitudes measured at one position longitudinally as we move the wire such that they become the generators of a cylinder inside the magnet aperture

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Optical sensors Phototransistor Sharp GP1S094HCZ0F Response of the Phototransistors

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Use Wire Displacements Proposition: We are done if:

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solution of the Wave Equation (Assumptions)

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Use Wire Displacements

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solution of the Wave Equation (Steady State)

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Check 2: Numerical simulation (FDTD) and the Steady State Solution

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solution of the Wave Equation III Check: Known longitudinal field or oscillation profiles Ideas welcome on how to measure the longitudinal profile of the oscillation wire (30 phototransistors, inductive, capacitive)

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solution of the Wave Equation IV The slackline The hard-edge (model) magnet

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Test Cases Air coil: Academic worst case LEP-IL-QS The “blue” magnet

S. Russenschuck, CLIC-Workshop, WP2-Pacman, The Air Coil Longitudinal field distribution Longitudinal shape of the wire oscillation

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Convergence of the Modal Amplitude Functions

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Results for the Air Coil

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Results for the Blue Magnet

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Conclusion on the Wire Techniques  The classical stretched wire technique is routinely used for axis and gradient measurements  There is still a lot of potential in the oscillating wire technique  Because we measure the oscillation amplitude only at one point, we make in intrinsic error caused by the varying end fields as we move along the circular trajectory – The method is exact for the hard-edge (model) magnet and consequently for small-aperture magnets excited by rare-earth material – There is an intrinsic error because we measure only one amplitude. This error can be estimated when the numerical model is available – Effects from stage misalignment are much larger than the intrinsic error – We would be exact if it was possible to measure the shape of the wire oscillation

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Solution of the Wave Equation (Recall)

S. Russenschuck, CLIC-Workshop, WP2-Pacman, Longitudinal field Profiles Behavior around resonance frequencies

S. Russenschuck, CLIC-Workshop, WP2-Pacman,  Challenges – Bandwidth of the system – Intrinsic error – Noise at 1 kHz – Nonlinearities in the physical model – Tilt and swing alignment of the quadrupole  PACMAN R&D efforts – Measurement of oscillation profiles – New stages and wire tensioning systems – Fiducilization – Software framework (data and task manager) – “Intelligent” postprocessing (tension, multipoles) – String of magnets