Superferric Magnet Research Articles

Superconducting racetrack booster for the ion complex of MEIC

The current design of the Medium-energy Electron-Ion Collider (MEIC) project at Jefferson lab features a single 8 GeV/c figure-8 booster based on super-ferric magnets. Reducing the circumference of the booster by switching to a racetrack design may improve its performance by limiting the space charge effect and lower its cost. We consider problems of preserving proton and deuteron polarizations in a superconducting racetrack booster. We show that using magnets based on hollow high-current NbTi composite superconducting cable similar to those designed at JINR for the Nuclotron guarantees preservation of the ion polarization in a racetrack booster up to 8 GeV/c. The booster operation cycle would be a few seconds that would improve the operating efficiency of the MEIC ion complex.

Magnetic design and field optimization of a superferric dipole for the RISP fragment separator

The in-flight fragment separator of the Rare Isotope Science Project requires eight dipole magnets to produce a gap field of 1.7 T in a deflection sector of 30 degree with a 6-m central radius. If the beam-optics requirements are to be met, an integral field homogeneity of a few units (1 unit = 10-4) must be achieved. A superferric dipole magnet has been designed by using the Low-Temperature Superconducting wire NbTi and soft iron of grade SAE1010. The 3D magnetic design and field optimization have been performed using the Opera code. The length and the width of the air slots in the poles have been determined in an optimization process that considered not only the uniformity of the field in the straight section but also the field errors in the end regions. The field uniformity has also been studied for a range of operation of the dipole magnet from 0.4 T to 1.7 T. The magnetic design and field uniformity are discussed.

Fast-Ramped Superconducting Magnets for FAIR Production Status and First Test Results

The SIS100 synchrotron for heavy ion research is based on fast-ramped superconducting magnets. These superferric magnets are being designed, built, and tested. The first 3-m-long series dipole (maximum field of 1.9 T; ramp rate of 4 T/s) has been built. We present the test results obtained (quench training, magnetic field, ac loss, and repetition rate) and compare them with the predicted values and the required operation parameters.

Superconducting magnet system of in-flight separator for a heavy ion accelerator planned in Korea

An in-flight fragment separator, which aims to produce and study rare isotopes, consists of superferric quadrupole triplets and <TEX>$30^{\circ}$</TEX> dipole magnets to focus and bend the beams for achromatic focusing and momentum dispersion, respectively. The separator is divided into pre and main stages, and we plan to use superconducting magnets employing high-Tc superconductor (HTS) coils in the pre-separator area, where radiation heating is high. The HTS coils will be cooled by cold He gas in 20-50 K, and in the other area, superferric magnets using low-temperature superconductor (LTS) will be used at 4 K. A few LTS coils were wound and successfully tested in a LHe dewar, and the design of cryostat has been optimized. Development of the HTS coils is ongoing in collaboration with a group at KERI. An HTS coil of racetrack shape was wound and tested in a <TEX>$LN_2$</TEX> bath and in a dewar with cryocooler. No degradation on critical current due to coil winding was found.

Cryodiagnostics of SC-accelerators with Fast Cycling Superferric Magnets

Thе report concerns resistive temperature sensors, their calibration system and features to mount these sensors; RF-void fraction sensors and set-up to calibrate them; a discrete level-meter based on a resistive temperature sensor; and two-phase helium flow-meters. A way to produce a multi-channel measuring system is proposed to be applied for superconducting accelerators like FAIR-SIS100 and NICA. It is also shown that the experience obtained in cryo-diagnostics allows one to produce the separation less flow-meters for the three-phase oil-salty water-gas flows which are typical in the oil production industry.

First Results of the Magnetic Measurements of the Superconducting Magnets for the European XFEL

The European X-ray Free Electron Laser facility (XFEL) is currently under construction at DESY in the Hamburg area in Germany. A linear accelerator consisting of 102 accelerator modules is used to accelerate the electron beam. Each module contains eight superconducting RF cavities and one magnet package, all operating in a 2 K super-fluid helium bath. Each magnet package consists of three nested magnets. Two cos θ-type correction dipole magnets horizontal and vertical deflecting are glued onto the surface of the beam pipe being the inner wall of the cryostat vessel. They are inside of a superferric quadrupole magnet. Each magnet package together with a conduction cooled current lead assembly, based on a CERN design, will be tested at room temperature and at 2 K in a special cryostat XMTS at DESY. It allows access for the field measurement equipment into the magnet bore at room temperature by using an anti-cryostat. The cold magnet project is realized by three groups as in kind contributions to the XFEL project. CIEMAT designs and provides the magnets and DESY the current leads. Magnet testing at DESY is performed together with IFJ PAN. A description of the XMTS facility, the magnetic field measurement systems used (harmonic coils and stretched wire setups) are given. Finally a short discussion of the results obtained for the first third of the magnets is presented. All magnets tested so far perform very well up to the design current. The quality and strength of the magnetic field are as designed.

A Conduction Cooled High Temperature Superconductor Quadrupolar Superferric Magnet, Design and Construction

The paper presents the prototype of an YBCO superferric quadrupolar magnet for high gradient magnetic field generation, design and construction. The temperature of the superconducting coil has to be kept within safe limits or the HTS would exit the superconductive state. Of particular concern is the "warm" beam tube that passes through the magnet. Cryogenic conduction cooling with a closed cycle G-M Cooler may ensure the removal of the ambient heat influx. Numerical simulation results on the magnetic field and heat transfer problems are then discussed. The computational domain is abstracted out of the CAD design of the system. The design solution is presented and compared with the numerical simulations results.

Unconventional Purcell filter in superferric magnets in the Facility for Antiproton and Ion Research

For the magnets used in beam lines, especially in high resolution applications, the field quality ΔB/B is a very important factor which determines the quality of the beam after passing through the magnets. End-shaping of the poles and introduction of Purcell filters improve field uniformity. However, in most applications, what matters is the uniformity in the total field integrated along the beam path (Δ(∫Bdl)/∫Bdl). With this criterion in mind, we have used unconventional partially penetrating Purcell filters in designing wide aperture highly uniform dipole and quadrupole magnets for the large acceptance low energy beam line in the Super Fragment Separator of the upcoming Facility for Antiproton and Ion Research (FAIR) at Darmstadt. The weight of dipole magnets decreases by the use of such filters.

Analysis of the Performance of a Model Quadrupole Magnet for a Linear Accelerator

A model quadrupole magnet for a future linear accelerator has been designed, fabricated, and tested at KEK. The model quadrupole is a superferric superconducting magnet with a design field gradient of 57 T/m. The design field gradient is obtained by saturating the iron yoke. Superferric magnets are considered to have the advantage of simplicity, less sensitivity to the position of the superconductor coils, and are therefore thought to be easier to construct and less expensive than usual superconducting magnets. However, if the iron is heavily saturated, the magnetic field becomes more sensitive to the coil positions. The magnetic properties of the magnet were measured with a harmonic coil, and its field gradient, effective length, and multipole components were compared with a 3D simulation. The results are presented and discussed in this paper.

Fabrication and Testing of a Model Quadrupole Magnet for Linear Accelerators

A model of a quadrupole magnet for linear accelerators was designed, fabricated, and tested at KEK in order to gain fabrication experience and a better understanding of superconducting magnet characteristics. The assembly has a design field gradient of 56.5 T/m, an aperture of 92 mm, and a cold mass length of 680 mm. Furthermore, it is designed as a superferric magnet with four racetrack coils wound with a specially fabricated ribbon cable of eight superconducting strands. In this paper, we present details of the magnet design, fabrication, and the results of its cold tests. Data of the field measurements are also presented in brief.

Design of self-correction coils in a superferric dipole magnet

Design of self-correction coils in a superferric dipole magnet is carried out. By adopting the self-correction coil (SCC) scheme, we can do online correction of unwanted fields inside the magnet aperture during the whole operating cycle irrespective of their origin. The self-correction coils are short-circuited superconducting coils of required symmetry placed in the useful aperture of the AC dipole magnet. Design and operation mechanism of self-correction coils in a superferric dipole magnet are discussed in this paper.

Radiation Resistant Superferric Quadrupole Magnets With Warm Iron

The Facility for Rare Isotope Beams to be built at Michigan State University will be capable of providing beams of any element at energies of at least 200 MeV/u at beam powers of 400 kW. The fragment production target is in close proximity to the superconducting quadrupole magnets. These magnets have to operate in the high-radiation environment, with calculated radiation doses of more than 10 MGy per year. The design of a large bore, superferric quadrupole magnet that provides high field gradient of 15 T/m and effective length of 0.6 m is presented. The current design is “warm-iron” with a nominal yoke length of 520 mm and a pole radius of 135 mm. A coil design based on spinel insulated cable-in-conduit conductor that provides ample current margin provides significant long lifetime against radiation damage. The major challenges are the tight geometry, high forces and remote handling of an irradiated magnet. This paper presents the magnet design including coil forces and coil restraint system. In addition, coil properties, conductor stability and full mechanical details are also presented.

Compact superferric FFAG accelerators for medium energy hadron applications

Medium energy hadron beams are desirable in various applications such as accelerator-driven subcritical systems (ADSR), high intensity neutron sources and carbon therapy. Compactness and easy operation characters are important for this energy region, especially in the case of medical use purposes. This paper introduces a novel superferric scheme with scaling fixed-field alternating gradient (FFAG) accelerators, which can provide 400MeV/u carbon ions for cancer therapy. By employing a maximum field of 5T with a high field index, 8.5m diameter with 85cm radius excursion is achieved in a single FFAG ring. The lattice configuration and design of superferric magnet sectors with high permeability materials were described in detail. This scheme can also be extended to other hadron applications.

Design Study of Superconducting Corrector Magnets for SIS 100

Superconducting corrector magnets are planned to be installed at the SIS 100 accelerator ring for FAIR. The Nuclotron cable, used for the main dipole and quadrupole magnets, is adopted for the corrector magnets taking into account its advantages as high cooling efficiency and the compatibility to the whole accelerator lattice. The error compensation multipole corrector and the steerer are built as nested magnets to save longitudinal space in the ring, the chromaticity sextupole is a superferric magnet. We present the progress of design studies on these magnets.

The Superconducting Horizontal Bend Magnet for the Jefferson Lab's 11 GeV/c Super High Momentum Spectrometer

A collaboration between NSCL and Jlab has developed the reference design and coil winding for Jlab's Super High Momentum Spectrometer (SHMS) horizontal bend magnet. A warm iron ?C? type superferric dipole magnet will bend the 12 GeV/c particles horizontally by 3° to allow the SHMS to reach angles as low as 5.5°. This requires an integral field strength of up to 2.1 T.m. The major challenges are the tight geometry, high and unbalanced forces and a required low fringe field in primary beam path. A coil design based on flattened SSC Rutherford cable that provides a large current margin and commercially available fiberglass prepreg epoxy tape has been developed. A complete test coil has been wound and will be cold tested. This paper present the modified magnet design includes coil forces, coil restraint system and fringe field. In addition, coil properties, quench calculations and the full mechanical details are also presented.

Magnetic Field Design of the Dipole for Super-FRS at FAIR

The Super-FRS (Super FRagment Separator) is a part of FAIR (Facility for Antiproton and Ion Research), which will be constructed at GSI, Germany by 17 countries. The Super-FRS comprises 24 superferric dipole magnets. The 2D and 3D magnetic field simulations of the prototype magnet are described in this paper. A passive trim slot and four chamfered removable poles are used to satisfy the required field homogeneity which is better than at 1.6 T, 0.8 T and 0.16 T in a wide elliptical useable aperture of 380 mm 140 mm. Measurement results at various field levels are shown in this paper as well. It can be seen from the comparison of calculation and measurement results that the magnetic designs of the magnet fulfils the requirements.

The GSI Cryogenic Prototype Test Facility—First Experience Gained on 2-Phase-Flow Superconducting Prototype Magnets of the FAIR Project

The Facility of Antiproton and Ion Research (FAIR) will feature two superconducting fast ramped synchrotrons (SIS 100, SIS 300). The core components of this new facility are two-phase forced cooled superferric magnets ramped with 4 T/s up to 2 T and single-phase forced cooled costhetas magnets ramped with 1 T/s up to 4 T. The GSI test facility consists of 2 test benches. One of them is equipped with a universal cryostat and second one is dedicated to cryostated superconducting (SC) magnets. So far, one SC coil and one SC magnet have been tested. We report on the training, quench behavior of magnets and results of AC loss measurements.

Test Results of a Superconducting Quadrupole Model Designed for Linear Accelerator Applications

The first model of a superconducting quadrupole for use in a Linear Accelerator was designed, built and tested at Fermilab. The quadrupole has a 78 mm aperture, and a cold mass length of 680 mm. A superferric magnet configuration with iron poles and four racetrack coils was chosen based on magnet performance, cost, and reliability considerations. Each coil is wound using enamel insulated, 0.5 mm diameter, NbTi superconductor. The quadrupole package also includes racetrack type dipole steering coils. The results of the quadrupole design, manufacturing and test, are presented. Specific issues related to the quadrupole magnetic center stability, superconductor magnetization and mechanical stability are discussed. The magnet quench performance and results of magnetic measurements will also be briefly discussed.

Full Size Model Magnets for the FAIR SIS100 Synchrotron

The planned FAIR synchrotron SIS100 has to deliver high intensity beams. Following the JINR Nuclotron, GSI has chosen to build this machine using fast-cycling 4 T/s, 2 T superferric magnets. Cycle repetition rates of about 1 Hz cause high AC power losses in the magnet components. Eddy currents deteriorate the field quality. After millions of operation cycles and high radiation flux the coil support structure can loose mechanical stability. Therefore these effects were analyzed to warrant the magnet's performance over its lifetime. Following intensive experimental and computational investigations on short test models three full size dipoles and a 1.2 m long quadrupole with a maximum field gradient of 27 T/m in the aperture of 135 mm 65 mm will be manufactured until the end of 2007. Two of the dipoles are straight 2.7 m long 2.1 T magnets with a beam aperture of 130 mm 60 mm (width x height), while the third one is a curved 1.9 T dipole 3.0 m long with a reduced horizontal aperture of 115 mm. All the models use a superconducting hollow NbTi/Cu composite cable cooled with two-phase helium flow. The main design features and estimated operation parameters are given. In parallel preliminary tests of a 2.8 m SIS100 equivalent dipole system was performed. The cooling stability of the system at different SIS100 operation cycles was checked experimentally for the first time. These results are discussed as well as possible design options to fulfil additional operation requirements.

Design and Manufacturing Main Linac Superconducting Quadrupole for ILC at Fermilab

The design and manufacturing of the first model of an International Linear Collider (ILC) Main Linac superconducting quadrupole is in progress at Fermilab. The quadrupole has a 78 mm aperture, a 36 T integrated gradient, and a cold mass length of 700 mm. A superferric magnet configuration with iron poles and four racetrack coils was chosen based on magnet performance, cost, and reliability considerations. Each coil is wound using enamel insulated, 0.5 mm diameter, NbTi superconductor. The quadrupole package also includes shell type dipole steering coils. The results of the quadrupole design, including magnetic and mechanical analyses, are presented. Specific issues related to the quadrupole magnetic center stability, superconductor magnetization and mechanical stability are discussed and analyzed. The magnet quench protection system, current leads, and mounting the quadrupole inside ILC Main Linac cryomodule will also be briefly discussed.