Search

Dipoles and quadrupoles have been developed for use in a 12.5 GeV storage ring at the ZGS. The winding bore of these magnets is 10.16 cm with a useful aperture of 7.6 cm. The magnets produce a high quality field (±0.1% nonuniformity including the ends) that requires no correction at any field level. An operating current of 190 A at the design field of 30 kG allows the use of a very low heat leak cryostat design. A 3 meter length of magnets is expected to require only 2 liters helium per hour. Construction of 5 prototype modules, consisting of 2 dipoles and 2 quadrupole each, complete with cryostats, is almost completed.

The recovery of a normal zone produced in a superconducting magnet following a mechanical disturbance depends on the heat transfer rate to the liquid helium cooling channels. One of the factors which affects the heat transfer to the channel is the amount of vapor accumulated in the channel during and following a disturbance. The present work is undertaken to determine the void fraction in a liquid helium channel and to study the effect of the amount of vapor in the channel on the heat transfer characteristics. Heat pulses of 30 to 300 ms duration are introduced into the simulated conductor, and observations are made of the resulting temperature response and of the vapor fraction in the channel. The vapor fraction is determined by means of a capacitance bridge which responds to the small difference in dielectric constant between liquid and vapor helium. For completeness steady state measurements of temperature and vapor fraction are also reported.

Argonne National Laboratory is constructing a large superconducting MHD magnet to be used in the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute. Measurements of the mechanical properties of all the materials used in the superstructure (bore tube, cast flanges and deposited weld metal, cast girder segments, aluminum girders, tie plates and connecting pins) have been performed. These measurements consisted of tensile strength, yield strength, % elongation, and reduction of area at 295, 76 and 4 K. Charpy "V" notch impact tests at 23 K were used for material acceptance with additional impacts done at 76 and 295 K. To verify ductility at the 4 K operating temperature, elastic-plastic J-integral fracture toughness tests at 295, 76 and 4 K along with associated fatigue crack growth rate data were generated. Results of these measurements are discussed.

When a cryostable composite conductor carrying current experiences a heat input from a mechanical perturbation, a normal region develops which initially propagates and then either collapses or continues to propagate. A computer model has been devised to study this phenomenon. The model incorporates initial or continuing heat input from mechanical perturbations, heat conducted to the neighboring elements of the conductor and, if appropriate, heat conducted through insulation to neighboring turns. Heat is transferred to the helium coolant according to a specified heat transfer coefficient. If the element of conductor is in a normal or current-sharing state, resistive heating also occurs. The (unstable) equilibrium state of heat generation and conduction has been studied; results agree with those of a static calculation. The model has been validated against experimental measurements of response to heat pulses. A study of the trade-off between cross-sectional areas and wetted perimeter of a conductor is included, with recovery current presented as a function of perturbing energy.

The conceptual design of a 10-Tesla pure tension superconducting toroidal field coil (TFC) system has been developed in sufficient detail to define a realistic design for the TFC that could be built based upon the current state of technology with minimum technological extrapolations.

An experimental technique has been established to simulate the transient mechanical perturbation and to measure the minimum propagating current of a cryostable superconducting coil. The experimental setup is described. Typical waveforms of potential profiles across the normal zone and temperature profiles of the normal zone for both the propagating and recovery conditions are shown. Also presented are the measured recovery currents versus the perturbation energy under various external magnetic field strengths, heater lengths and heating durations. These data will be discussed and compared with data computed from a theoretical model.

A high gradient superconducting quadrupole has been designed and developed as the heavy ion beam focussing element in the low velocity portions of an rf linac for the Argonne Ion Beam Fusion Reactor. The quadrupole magnets will require an extremely short magnet coil length (∼ 20 cm to 30 cm) and extremely high central gradients (∼ 100 T/m to 200 T/m). The useful warm bore will be about 4 to 6 cm and the integral gradient homogeneity should be constant to ± 5% over the useful warm bore. Special techniques have been developed which are especially suitable for multi-layer coil winding and coil assembly with high average current density over the coil cross section. A 5-layer quadrupole with 9 cm winding bore has been built and tested to the full performance of about 100 T/m with little training. The achieved average current density is 22,000 A/cm2at a peak field in conductor of about 5.0 T. An 8-layer quadrupole is under construction for a design gradient of 140 T/m over 9 cm winding bore. The peak field will be about 7.2 T.

The Argonne National Laboratory has designed and is constructing a superconducting dipole magnet system for use in the bypass loop of the U-25 MHD facility in Moscow. Presented in detail are the system design parameters. Reviewed are the magnet geometry, stability criteria, cryostat thermal and mechanical design, cryogenic system parameters, and controls. Details of the servo mechanism winding machine, the epoxy fiberglass tension member support system, and the diagnostic instrumentation system for monitoring of the magnet's thermal parameters, structural forces and component accelerations during system cool-down and with the Magnetohydrodynamics (MHD) channel in operation are included.

As an integral effort in the Argonne Tokomak Experimental Power Reactor Conceptual Design, design studies on the superconducting ohmic heating (OH) coils and the superconducting equilibrium field (EF) coils were completed. These conceptual designs are developed in sufficient detail with clear information on high current ac conductor design, cooling, venting provision, coil structural support, and zero loss poloidal coil cryostat design. Also investigated is the EF field penetration into the blanket and shield.

This work was undertaken to study the vapor formation and heat transfer of multiple layers under both steady state and transient conditions. The change in capacitance between the two sides of the heated channel is measured to determine the volume fraction of the vapor in the cooling channel. It is found that the heat transfer characteristics depend on the vapor accumulation and the velocity of vapor flow. The vapor locking heat flux is decreased when the vapor accumulation is increased.

A conductor for a cryostable magnet is usually made by soldering a superconducting matrix to an OFHC copper strip. The presence of voids between the matrix and the stabilizer due to the imperfection in the soldering bond is of great concern to magnet designers. An experiment was set up to investigage the effect of the void on the characteristics of hot end recovery and cold end recovery for CFFF superconductors. Tests were made on samples having different lengths of soldering void under various magnetic field strengths and injecting energies. The recovery current and the temperature distributions along the matrix and the copper stabilizer were mentioned. The test results are presented.

POPAE, the proposed Proton-Proton Intersecting Storage Ring Facility at Fermi National Accelerator Laboratory, will require some 1400 superconducting 6.0 T DC dipole and quadrupole magnets. The dipoles are 6. 17 m long and consist of coils of rectangular cross section clamped directly onto the 6 cm inner diameter bore tube. Aluminum is used to support the coils, and they are wound from a rectangular monolithic 2:1 copper to NbTi filamentary conductor. An experimental program has been undertaken to test and select the size, type and internal support scheme of the conductor. Individual coils of the POPAE dipole design, foreshortened to 0.5 m but supported similarly to the full-sized magnet are being tested in the field of a 2. 0 T backing magnet modeled after the Argonne SSR magnets. We also describe the large-scale cryogenics installation needed for the facility.

We have designed and built a superconducting magnet for a large polarized proton target. The magnet consists of a pair of thick Helmholtz coils. Each Helmholtz coil consists of 9 step-subcoils balancing the ampere-turns around the Helmholtz line, thus providing an optimum for field uniformity without the help of Correction coils. This magnet generates 25 kilogausses with field uniformity one part in 10,000 over more than 5 cm diameter spherical target volume. It was designed to allow a large warm bore of 34.5 cm with axial aperture of 96° and between the Helmholtz pair, a wide warm separation of 12.7 cm with transverse aperture of 23°, thus allowing large accessibility to the proton target and for the scattering detectors in high energy scattering experiments.

The Argonne National Laboratory has constructed a large aperture superconducting MHD magnet for use in the Coal-Fired Flow Facility at the University of Tennessee Space Institute at Tullahoma, Tennessee. The magnet will generate a peak on-axis field of 6 T in a MHD warm bore of 80 cm diameter at inlet, 100 cm diameter at exit, and 300 cm effective length. The stored energy of the magnet will be 168 MJ, the cold mass (4.2 K) will be 131 metric tons and the ampere-turns, 13.7 × 106. The final design of the magnet will be briefly introduced. Described in detail are the experiences of coil winding and coil assembly, the assembly of force-containment superstructure and assembly of magnet cryostat.

Two superconducting solenoids have been designed and built for the Argonne Zero Gradient Synchrotron (ZGS) Polarized Proton Beam Facility. Each solenoid will have a central field of 8.0 T, an effective field length of about 1.75 m, and a cold clear bore of 11.5 cm. It will generate a spin-tipping integral field of about 14 T-m. The integral field homogeneity over the cold bore is ± 4%. The magnet stored energy is about 0.7 MJ. Described in detail is the stability simulation on a high current density intrinsic stable coil. Comparisons are made between the simulation data and data obtained from the magnet performance tests. The cryostat design and construction are also presented.

The Argonne National Laboratory has designed and is constructing a 6 T large aperture superconducting MHD magnet for use in the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute (UTSI) at Tullahoma, Tennessee. The magnet system consists of the superconducting magnet, a magnet power supply, an integrated instrumentation for operation, control and protection, and a complete cryogenic facility including a CTI Model 2800 helium refrigerator/ liquefier with two compressors, helium gas handling system and a 7500 liter liquid helium dewar. The complete system will be tested at Argonne, IL in 1981. This paper first briefly reviews the magnet design. Second, the coil fabrication programs are described in detail.

The Argonne National Laboratory is designing and will build a large superconducting dipole magnet system for use in the Coal Fired Flow MHD Research Facility at the University of Tennessee Space Institute (UTSI). Presented in detail are the conceptual design of the magnet geometry, conductor design, cryostability evaluation, magnetic pressure computation, structural design, cryostat design, and the cryogenics system design.

Superconductors used in a large superconducting magnet system are generally designed to be cryostable. There exists a strong possibility that cryostable conductor will burn out in a helium gas environment should a normal zone be generated from any point of the coil above the liquid helium level. An experiment is set up to investigate the heating of a cryostable conductor in a helium gas environment. Results will be presented and the ultimate safety of a cryostable conductor will be discussed.

A superconducting high energy physics beam line 60 meters long is now operating at the Argonne National Laboratory Zero Gradient Synchrotron (ZGS). The line transports 12 GeV/c polarized protons to a large particle spectrometer. It consists of ten superconducting dipoles, two superconducting quadrupoles, and several conventional magnets. The superconducting magnets are contained in four cryostats; three 3-dipole cryostats, each 3.5 meters long; and one quad-dipole-quad (QDQ) cryostat 2.7 meters long. The superconducting magnets have a useful aperture of 7.6 cm diameter. At 12 GeV/c the dipoles operate at 2.6 T over 91 cm, with 160 amperes, and the quadrupoles at 0.31 T/cm over 41 cm, with 190 amperes. The cryostat installation, initial cooldown, boil-off gas recovery system, power supply controls, beam optics, and operating experience are presented.