Search

The U.S. SCMS superconducting dipole magnet system consists of the superconducting magnet and its cryostat, a helium liquefier and refrigerator/liquefier facility, helium storage dewars, the transfer line, power supply, and a complete system for magnet instrumentations and control. The magnet system has been designed [1–3] and built by Argonne National Laboratory. The entire magnet system was successfully tested to full design field in May 1977. It was then delivered to Moscow in June 1977, and the first energization of the magnet system is expected in early 1978.

Argonne National Laboratory is building a large superconducting dipole magnet[1] for MHD research at the University of Tennessee Space Institute-Coal Fired Flow Facility (UTSI-CFFF). In designing such a large (170-MJ stored energy) magnet, great attention must be devoted to the safety of the magnet and personnel. The conductor for the UTSI-CFFF magnet incorporates significant copper stabilizer, which both insures its cryostability [2] and contributes to the magnet safety. This paper first presents the quench analysis, followed by the cryostat fault condition analysis. Two analyses of exposed turns follow: The first shows that gas cooling protects uncovered turns, and the second that the cryostat pressure relief system protects them. Finally the failure mode and safety analysis is presented.

A conceptual design on the superconducting ohmic heating (OH) coil has been made for the GA/ANL TNS tokamak reactor studies. The primary advantage of a superconducting OH coil is the minimization of equipment and operational costs. This is primarily a result of the much reduced power supply and energy storage costs. Three-hundred megawatt peak power and 11-MW rms power would be required to drive a room-temperature copper OH coil system, as opposed to 16 and 4 MW, respectively, for a superconducting OH coil. Another reason is that, to reduce the overall TNS tokamak cost, the flux core of OH coils should be small. However, a much better utilization of the flux core can be achieved with superconducting OH coils by placing the support cylinder of superconducting toroidal field (TF) coils within the inner diameter of the superconducting OH coils, thus allowing the outer diameter of the OH coils to be in close contact with TF coils. Recent scoping studies indicate that superconducting OH coils will cost only half as much as room-temperature copper OH coils [1].

The Argonne National Laboratory, under the sponsorship of the Fossil Energy Division of the U. S. Department of Energy, has designed and is constructing a 6-T, 0.8-m minimum warm bore superconducting dipole magnet system for magnetohydrodynamic (MHD) research. The system will be installed and operated at the University of Tennessee Space Institute (UTSI) Coal Fired Fuel Facility (CFFF). The system will consist of a coil assembly contained in a liquid helium cryostat, a helium refrigerator/liquefier system, and controls and instrumentation for cooldown and steady-state operation[1–4]

The technology of stable superconducting magnets has become synonymous with the study and use of composite conductors. The composite conductor, a superconductor paralleled with a normal metal, helps provide magnet stability by supplying alternate electrical and thermal paths for the superconductor when it becomes normal. If these alternate paths of normal metal can carry the total transport current continuously and still remain below the transition temperature of the superconductor, the composite conductor is said to be cryostable. The operational definition of cryostability requires sufficient cooling to dissipate Joule heating.

In a large superconducting magnet, such as the superconducting magneto-hydrodynamic (MHD) dipole system for the National Coal-Fired Flow Facility (CFFF SCMS) at the University of Tennessee Space Institute (UTSI), the conductor joints must be strong, highly reliable, of low resistance, reproducible, and made with reasonable speed. These aspects of conductor joining are being studied.

Linen-base phenolic laminate is inexpensive, has high compressive mechanical strength, and can be easily fabricated. It has been widely used for substructures in large bubble-chamber magnets [1] and large magnetohydrodynamic (MHD) magnets [2,3]

Recent advances in hybridoma technology have led to the development of specific monoclonal antibodies to a variety of tumor-associated antigens. The high degree of specificity of such reagents has rekindled interest in their application to immunotherapy of malignancies. In-vitro culture studies and experiments in various in-vivo animal models have usually shown that monoclonal antibodies, even in the presence of complement, are rarely alone sufficiently cytotoxic and therefore usually ineffective for tumor destruction (1,2). This ineffectiveness of monoclonal antibodies when used in unmodified forms has been partially attributed to the heterologous distribution of tumor-associated antigens on tumor cell surfaces which therefore results in an insufficient attachment of monoclonal antibodies to different tumor cells; more to those cells which have a significant number of binding sites for the antigen but none to other tumor cells that are devoid of binding sites for the specific antigen (3). Thus, while tumor cells which express the specific antigen may under appropriate circumstances undergo lysis, those which are negative for the antigen are spared and continue to proliferate. Monoclonal antibodies directed to tumor-associated antigens which are coupled to various toxins suffer from the same shortcomings that have been described for unmodified antitumor monoclonal antibodies.

A proposed positron-electron project (PEP) spectrometer [1] requires a thin solenoid 3.0 m in diameter and 3.5 m in length, with a central field of 1.5 T and an overall thickness of coil and cryostat with less than two-thirds radiation length, X0.

The superconducting magnet system (SCMS) consists of a superconducting magnet, magnet cryostat, a helium refrigerator/liquefier facility, a helium gas-handling system, apparatus for cryogenic transfer and storage, a magnet power supply, an integrated instrumentation and control system including a computer for magnet operation, data acquisition, system status and diagnosis, and magnet protection. The complete system will be tested at Argonne and installed at the Coal-Fired Flow Facility (CFFF) at the University of Tennessee Space Institute (UTSI) in 1981. The cryogenic aspects and magnet safety are described and analyzed elsewhere [1,2].

Aluminum is a potentially important material as a cryostatic stabilizer for superconducting magnets [1]. Aluminum has several advantages over copper as a stabilizer: high-purity aluminum has much less resistivity than that of the oxygen-free grades of copper at 4.2 K and the density of aluminum is less than one-third of that of copper. In certain cases, aluminum must be used. For example, a super-conducting magnet for the PEP spectrometer [2] must use an aluminum-stabilized superconductor to satisfy the requirement of the short radiation length.

Turn-to-turn electrical shorts in a superconducting magnet can occur during coil winding or coil assembly under compression. Shorts may also appear due to additional magnetic pressure during energizing of the magnet. During the fabrication of the U. S. Superconducting Magnet System for the bypass loop of the U-25 MHD facility [1], a short was detected in the inner layer at the high-field region.