Carlo Petrone

Vibrating-wire measurement method for centering and alignment of solenoids

A method is proposed to center and align solenoids by means of a vibrating wire. The magnetic axis of a solenoid is defined as the path where the integral over the transversal field components takes its minimum. The wire, fed by an alternating current, oscillates in a plane that is perpendicular to the transversal magnetic field. When the wire position coincides with the magnetic axis, the transversal field components cancel out and therefore no motion is induced. To center and align the solenoid two wire resonance frequencies are excited for co- and counter-directional movements of the wire stages. The procedure to find the minimum oscillation amplitudes is sensitive to misalignment in the micrometer range. The experimental validation was carried out on a solenoid for the linear accelerator Linac4 at CERN.

Multipole correction of stretched-wire measurements of field-gradients in quadrupole accelerator magnets

A correction of field gradients in quadrupole accelerator magnets measured by stretched-wire methods is described. The gradient is first measured by means of the single-stretched-wire method. By using the same experimental setup, the relative multipole-field errors of the quadrupole are then measured by means of the oscillating-wire technique and used for the correction scheme. Results of the experimental validation are presented for a prototype quadrupole for the CLIC accelerator study at CERN.

Status of the 16 T Dipole Development Program for a Future Hadron Collider

A next step of energy increase of hadron colliders beyond the LHC requires high-field superconducting magnets capable of providing a dipolar field in the range of 16 T in a 50-mm aperture with accelerator quality. These characteristics could meet the requirements for an upgrade of the LHC to twice the present beam energy or for a 100-TeV center of mass energy future circular collider. This paper summarizes the activities and plans for the development of these magnets, in particular within the 16 T Magnet Technology Program, the WP5 of the EuroCirCol, and the U.S. Magnet Development Program.

Performances of the Main Beam Quadrupole Type1 Prototypes for CLIC

A critical magnet family for the future Compact Linear Collider (CLIC) is the Main Beam Quadrupole (MBQ) one. These magnets, placed along the two main linacs, will be actively stabilized in the nanometre range and are one of the key elements for reaching the outstanding nanometric dimensions and luminosity of the colliding beams. In the framework of the CLIC R&D and prototypes procurement for the CLIC Test Facility under construction at CERN, several prototypes of MBQ were procured. The MBQ magnet has a classical electro-magnetic design. A challenging aspect of the design is the extremely high mechanical precision required for the manufacturing and assembly of the iron quadrants. The challenging manufacturing aspects are presented and discussed. Results on the realized prototypes are discussed.

The EuCARD2 Future Magnets Program for Particle Accelerator High-Field Dipoles: Review of Results and Next Steps

The EuCARD2 collaboration aims at the development of a 10 kA-class superconducting, high current density cable suitable for accelerator magnets, to be tested in small coils and magnets capable to deliver 3-5 T when energized in stand-alone mode, and 15-18 T when inserted in a 12-13 T background magnet. REBCO tape, assembled in a Roebel cable, was selected as conductor. The developed REBCO tape has reached a record engineering critical current density, at 4.2 K and 18 T of

Measurement and Analysis of the Dynamic Effects in an HTS Dipole Magnet

{\text{956 A/mm}}^{2}

DESIGN, ASSEMBLY AND FIRST MEASUREMENTS OF A SHORT MODEL FOR CLIC FINAL FOCUS HYBRID QUADRUPOLE QD0

. Roebel cable carried up to 13 kA at 20 K when tested in a small coil (FeatherM0.4). Then a first dipole magnet, wound with two low-grade Roebel cables of 25 m each, was assembled and tested. The dipole reached the short sample critical current of 6 kA generating more than 3 T central field at about 5.7 K, with indications of good current transfer among cable strands and of relatively soft transition. The construction of a costheta dipole is also discussed. Eucard2 is reaching its objective and is continuing with the H2020-ARIES program aiming at doubling the Je at 20 T to obtain 6 T as standalone and 18 T as insert in a high field facility.

DEVELOPMENT OF UPGRADED MAGNETIC INSTRUMENTATION FOR CERN REAL-TIME REFERENCE FIELD MEASUREMENT SYSTEMS

The EuCARD-2 project, co-funded by the European Commission, supports the design, production, and standalone cold testing of a high-temperature superconducting demonstrator insert-magnet. The so-called Feather-M2 dipole magnet was built at CERN, using Roebel cable consisting of REBCO coated conductor tapes. In this paper, we will discuss the preparation and results of the magnetic measurements performed on the Feather-M2 model magnet, operated in forced-flow helium gas. For this test, the magnet was instrumented with cryogenic Hall-Sensors, which are cross-calibrated “ in situ” using induction-coil sensors. We present the measurement procedure, the instrumentation used, and the measurement results. These include the transfer function and dynamic field effects. The most exciting scientific result is the low level of persistent current effects observed in this model magnet.