• S. Caspi, D.W. Cheng, D.R. Dietderich, H. Felice, P. Ferracin, R.R. Hafalia, R. Hannaford, G.L. Sabbi
  LBNL, Berkeley, California
• G. Ambrosio, R. Bossert, V. Kashikhin, D. Pasholk, A.V. Zlobin
  Fermilab, Batavia
• M. Anerella, A.K. Ghosh, J. Schmalzle, P. Wanderer
  BNL, Upton, Long Island, New York

Funding: This work was supported in part by the Director, Office of Science, High Energy Physics, U.S. Department of Energy under contract No. DE-AC02-05CH11231

Pushing accelerator magnets beyond 10 T holds a promise of future upgrades to machines like the Large Hadron Collider (LHC) at CERN. Nb3Sn 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 (120mm) IR quadrupole (HQ) capable of reaching 15 T at its conductor peak field. The 1 m long two-layer coil, based on the design of the LARP TQ quadrupole series that achieved 230 T/m in a 90 mm bore, will demonstrate additional features such as alignment and accelerator field quality while exploring the magnet performance limits in terms of gradient, forces and stresses. In this paper we summarize the design and report on the magnet construction progress.

• X. Wang, S. Caspi, D.W. Cheng, H. Felice, P. Ferracin, R.R. Hafalia, J.M. Joseph, A.F. Lietzke, J. Lizarazo, A.D. McInturff, G.L. Sabbi
  LBNL, Berkeley, California
• K. Sasaki
  KEK, Ibaraki

Funding: U.S. Department of Energy

The Superconducting Magnet Program at Lawrence Berkeley National Laboratory has designed and tested HD2, a 1 m long Nb3Sn accelerator-type dipole with a 42 mm clear bore. HD2 is based on a simple block-type coil geometry with flared ends, and represents a step towards the development of cost-effective accelerator quality magnets operating in the range of 13-15 T. The design was optimized to minimize geometric harmonics and to address iron saturation and conductor magnetization effects. Field quality was measured during recent cold tests. The measured harmonics are presented and compared to the design values.

• P. Ferracin, S. Caspi, H. Felice, D. Leitner, C.M. Lyneis, S. Prestemon, G.L. Sabbi, D.S. Todd
  LBNL, Berkeley, California

Third generation Electron Cyclotron Resonance (ECR) ion sources operate at rf frequencies between 20 and 30 GHz and employ NbTi superconducting magnets with a conductor peak field of 6-7 T. A significant gain in performance can be achieved by replacing NbTi with Nb3Sn, allowing solenoids and sextupole coils to reach a field of 15 T in the windings. In this paper we describe the design of a Nb3Sn superconducting magnet for a fourth generation ECR source operating at a rf frequency of 56 GHz. The magnet design features a configuration with an internal sextupole magnet surrounded by three solenoids. A finite element magnetic model has been used to investigate conductor peak fields and the operational margins. Results of the numerical analysis are presented and discussed.