High temperature superconducting (HTS) machines have been demonstrated to benefit applications requiring high power density and torque. However, power density of existing superconducting machinery is limited by achievable flux density in the air gap and could be significantly increased with larger rotor currents. We propose a rotor based on MgB 2 conductor running in persistent current mode. A novel MgB 2 HTS flux pump transformer enables currents of several thousand amps in the rotor in a persistent mode. Large cryogenic heat loads associated with current leads are diminished by using a flux pump transformer for rotor excitation. All coils in the rotor and flux pump transformer are based on the double-helix winding configuration, which offers unmatched rotor robustness and reliability. This winding configuration also facilitates large bending radii, leading to an outstanding stress management and thus improved current carrying capacity of stress sensitive HTS conductors. The research presented in this paper analyses the performance of such a system through the design of a synchronous rotor for motors, generators and synchronous condensers.

We describe a technology for creating easy-to- manufacture combined function magnets. The field is produced by double-helix coils in which the axial path of the windings is defined by a sinusoidal function containing the superposition of the desired multipoles. The result is a magnet that can contain, for example, a pure dipole field with superimposed multipole fields whose magnitude relative to the dipole field can be easily controlled to any level. We show how low level (i.e. 0.1%-1%) modulation amplitudes of the superimposed multipoles can be used as built-in or "free" correction coils to compensate for iron saturation effects or geometrically-induced multipoles. The combined function winding can also be used to superimpose a dipole and quadrupole winding where the quadrupole integral of Gdl can be adjusted to any level desired over the length of the main dipole magnet. In this way a "free" quadrupole can be obtained within a dipole. The characteristics of this type of combined function magnet are also discussed.

HIF 2004 Symposium - Presentation code TH.I-13 Development of Superconducting Magnet Systems for HIF Experiments* Corresponding/first author: Gian Luca Sabbi Lawrence Berkeley National Laboratory 1 Cyclotron Road Berkeley, CA 94720 Phone: (510) 495-2250 Email: GLSabbi@lbl.gov Co-authors: A. Faltens, M. Leitner, A. Lietzke, P. Seidl, LBNL, Berkeley, CA S. Lund, N. Martovetsky, LLNL, Livermore, CA L. Chiesa, C. Gung, J. Minervini, J. Schultz, MIT-PSFC, Boston, MA C. Goodzeit, P. Hwang, Consultants W. Hinson, R. Meinke, AML, FL *Supported by the Office of Energy Research, U.S Department of Energy, at LBNL and LLNL under contract numbers DE-AC03-76SF00098, W-7405-Eng-48, and at MIT under contract number DE-FC02-93-ER54186. Abstract— The U.S. Heavy Ion Fusion program is developing superconducting focusing quadrupoles for near-term experiments and future driver accelerators. Following the fabrication and testing of several models, a baseline quadrupole design was selected and further optimized. The first prototype of the optimized design achieved a conductor- limited gradient of 132 T/m in a 70 mm bore, with measured field harmonics within 10 parts in 10 4 . In parallel, a compact focusing doublet was fabricated and tested using two of the first-generation quadrupoles. After assembly in the cryostat, both magnets reached

The U.S. Heavy Ion Fusion program is developing superconducting focusing quadrupoles for near-term experiments and future driver accelerators. Following the fabrication and testing of several models, a baseline quadrupole design was selected and further optimized. The first prototype of the optimized design has achieved a conductor-limited gradient of 132 T/m in a 70 mm bore, with measured field harmonics within 10 parts in 10(4). In parallel, a compact focusing doublet was fabricated and tested using two of the first-generation quadrupoles. After assembly in the cryostat, both magnets reached their conductor-limited quench current. Further optimization steps are currently underway to improve the performance of the magnet system and reduce its cost. They include the fabrication and test of a new prototype quadrupole with reduced field errors as well as improvements of the cryostat design for the focusing doublet. The prototype focusing units will be installed in the HCX beamline at LBNL, to perform accelerator physics experiments and gain operational experience. Successful results in the present phase will make superconducting magnets a viable option for the next generation of integrated beam experiments. (c) 2005 Elsevier B.V. All rights reserved.

The magnet system of the collider consists of superconducting dipole, quadrupole and correction magnets for guiding and focusing the beams through the regular arcs of the machine lattice as well as into collision at the six interaction points. It is designed to allow operation in the energy range 30–100GeV/u. Operation with either equal or unequal ion species in the colliding beams is possible, imposing a ratio of up to 2.5:1 in the magnetic fields of the two rings. There are 1740 superconducting magnets in the machine. They were designed to meet stringent requirements on field quality, reproducibility, and long-term reliability while being inexpensive to produce. Wherever feasible, production of magnets and components was carried out in industry, always with build-to-print designs. After several years of operation, no magnet has failed and the magnet system has proven reliable and functional.

Compact superconducting quadrupole magnets with a total length of 150 mm, an integrated gradient of about 13 T, and good field quality are needed for the High Current Transport Experiment (HCX) at Lawrence Berkeley National Laboratory. The Advanced Magnet Lab, Inc. has developed a novel concept, called multi-cylinder coils, which is ideally suited for this application. In this concept a round mini-cable is placed in grooves, which are precisely machined in flat support plates. The plates are stacked on top of each other to build up multilayer coils. The grooves guarantee precise placement of the conductor with high design flexibility, giving unique control over random and systematic field errors and management of mechanical stress. The designed quadrupole consists of four subcoils, which form the four sides of a square cross section box. Each subcoil is built up from 6 plates, accommodating 6 layers of conductor. The complete quadrupole is wound from a continuous conductor with no internal splices. Test results from the first prototype magnet are presented

The Superconducting Super Collider (SSC) has two counterrotating 20-Te V proton beams that will be made to collide at specific interaction points to carry out high energy physics experiments (see Figure 1). The Collider ring has two sites, West and East, for such Interaction Regions (IRs), and the conceptual design of the East Interaction Region is underway. The East IR, in the present stage of design, has two interaction points, the requirements for which have been specified in terms of distance L* to the nearest (focusing quadrupole) magnet and the beam luminosity. Based on these requirements, the optics for transition from arc regions or utility regions to the IR and for focusing (beta squeeze) the beams have been obtained.1 The arrangement of superconducting magnets in the IR is shown in Figure 2. The optical arrangement consists of a tuning section of quadrupoles, the strength of which is adjusted to obtain the required beta squeeze; a pair of bending dipoles to reduce the beam separation from the nominal 900 mm to 450 mm; an achromat section of quadrupoles, which consist of two cold masses in one cryostat; another pair of dipoles to bring the beams together at the required crossing angle; and a set of final focus quads facing the interaction point.

Over a period of ten months, a 15 m-long, 50 mm-aperture superconducting SSC Collider dipole was taken through a series of thermal and power cycles to check for changes in performance. One quench below operating current was experienced during this period. Small changes in the coil preload and certain harmonics were observed.<>

The quench performance and ramp rate sensitivity of 18 5-cm-aperture, 15-m-long Superconducting Super Collider (SSC) dipole magnet prototypes are discussed. All the magnets appear to reach a quench plateau near their extrapolated short sample current limit and well in excess of the operating current with very little training. Most of the magnets, however, exhibit a dramatic degradation of their quench current as a function of ramp rate, which, for the most part, can be attributed to large cable eddy currents.<>