Showing papers by "Giorgio Ambrosio published in 2009"

Design of HQ—A High Field Large Bore ${\rm Nb}_{3}{\rm Sn}$ Quadrupole Magnet for LARP

Abstract: In support of the Large Hadron Collider luminosity upgrade, a large bore (120 mm) Nb3Sn quadrupole with 15 T peak coil field is being developed within the framework of the US LHC Accelerator Research Program (LARP). The 2-layer design with a 15 mm wide cable is aimed at pre-stress control, alignment and field quality while exploring the magnet performance limits in terms of gradient, forces and stresses. In addition, HQ will determine the magnetic, mechanical, and thermal margins of Nb3Sn technology with respect to the requirements of the luminosity upgrade at the LHC.

Fabrication and Test of LARP Technological Quadrupole Models of TQC Series

Abstract: In support of the development of a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade, several two-layer technological quadrupole models of TQC series with 90 mm aperture and collar-based mechanical structure have been developed at Fermilab in collaboration with LBNL. This paper summarizes the results of fabrication and test of TQC02a, the second TQC model based on RRP Nb3Sn strand, and TQC02b, built with both MJR and RRP strand. The test results presented include magnet strain and quench performance during training, as well as quench studies of current ramp rate and temperature dependence from 1.9 K to 4.5 K.

Development and Coil Fabrication for the LARP 3.7-m Long Nb3Sn Quadrupole

Abstract: The U.S. LHC Accelerator Research Program (LARP) has started the fabrication of 3.7-m long Nb3Sn quadrupole models. The Long Quadrupoles (LQ) are ldquoProof-of-Principlerdquo magnets which are to demonstrate that Nb3Sn technology is mature for use in high energy particle accelerators. Their design is based on the LARP Technological Quadrupole (TQ) models, developed at FNAL and LBNL, which have design gradients higher than 200 T/m and an aperture of 90 mm. The plans for the LQ R&D and a design update are presented and discussed in this paper. The challenges of fabricating long accelerator-quality Nb3Sn coils are presented together with the solutions adopted for the LQ coils (based on the TQ experience). During the fabrication and inspection of practice coils some problems were found and corrected. The fabrication at BNL and FNAL of the set of coils for the first Long Quadrupole is in progress.

Quench Performance of a 4-m Long ${\rm Nb}_{3}{\rm Sn}$ Shell-Type Dipole Coil

Abstract: Fermilab has finished the first phase of Nb3Sn technology scale up by testing 2-m and 4-m long shell-type dipole coils in a dasiamagnetic mirrorpsila configuration. The 2-m long coil, made of Powder-in-Tube (PIT) Nb3Sn strand, reached its short sample limit at a field level of 10 T. The 4-m long coil, made of advanced Nb3Sn strand based on the Restack Rod Process (RRP) of 108/127 design, has been recently fabricated and tested. Coil test results at 4.5 K and 2.2 K are reported and discussed.

Quench Tests and FEM Analysis of ${\rm Nb}_{3}{\rm Al}$ Rutherford Cables and Small Racetrack Magnets

Abstract: In collaboration between NIMS and Fermilab, we have made copper stabilized Nb3Al Rutherford cables, using Nb-matrixed and Ta-matrixed strands. First these cables were investigated at high current in low self field using a flux pump. Using these Rutherford cables, we built and tested small racetrack magnets. The magnet made with the Nb-matrixed strand showed the flux jump instability in low field. The small racetrack magnet wound with the Ta-matrixed Nb3Al Rutherford cable was very stable at 4.5 K operation without any instability, as well as at 2.2 K operation. With the successful operation of the small racetrack magnet up to its short sample data, the feasibility of the Nb3Al strand and its Rutherford cable for their application to high field magnets is established. The characteristics of Nb3Al Rutherford cable is compared with that of the Nb3Sn Rutherford cable and the advantages of Nb3Al Rutherford cable are discussed.

Analysis of Voltage Spikes in Superconducting ${\rm Nb}_{3}{\rm Sn}$ Magnets

Abstract: Fermi National Accelerator Laboratory has been developing a new generation of superconducting accelerator magnets based on niobium tin (Nb3Sn). The performance of these magnets is influenced by thermo-magnetic instabilities, known as flux jumps, which can lead to premature trips of the quench detection system due to large voltage transients or quenches at low current. In an effort to better characterize and understand these instabilities, a system for capturing fast voltage transients was developed and used in recent tests of R&D model magnets. A new automated voltage spike analysis program was developed for the analysis of large amount of voltage-spike data. We report results from the analysis of large statistics data samples for short model magnets that were constructed using MJR and RRP strands having different sub-element size and structure. We then assess the implications for quench protection of Nb3Sn magnets.

Design and Construction of a 15 T, 120 mm Bore Ir Quadrupole Magnet for LARP

Abstract: Pushing accelerator magnets beyond 10 T holds a promise of future upgrades to machines like the Large Hadron Collider (LHC) at CERN. Nb{sub 3}Sn conductor is at the present time the only practical superconductor capable of generating fields beyond 10 T. In support of the LHC Phase-II upgrade, the US LHC Accelerator Research Program (LARP) is developing a large bore (120 mm) IR quadrupole (HQ) capable of reaching 15 T at its conductor peak field and a peak gradient of 219 T/m at 1.9 K. While exploring the magnet performance limits in terms of gradient, forces and stresses the 1 m long two-layer coil will demonstrate additional features such as alignment and accelerator field quality. In this paper we summarize the design and report on the magnet construction progress.