The test facility used for R&D testing of full scale development dipole magnets for the SSC is described. The Fermilab Magnet Test Facility, originally built for production testing of Tevatron magnets, has been substantially modified to allow testing also of SSC magnets. Two of the original six test stands have been rebuilt to accommodate testing of SSC magnets at pressures between 1.3 Atm and 4 Atm and at temperatures between 1.8 K and 4.8 K and the power system has been modified to allow operation to at least 8 kA. Recent magnets have been heavily instrumented with voltage taps to allow detailed study of quench location and propagation and with strain gage based stress, force and motion transducers. A data acquisition system has been built with a capacity to read from each SSC test stand up to 220 electrical quench signals, 32 dynamic pressure, temperature and mechanical transducer signals during quench and up to 200 high precision, low time resolution, pressure, temperature and mechanical transducer signals. The quench detection and protection systems is also described.

Fermilab r&d test facility for ssc magnets

The measurement system and procedures used to test more than 900 superconducting dipole magnets and more than 275 superconducting quadrupole magnets for the Fermilab Energy Saver are described. The system is designed to measure nearly all parameters relevant to the use of the magnets in the accelerator including maximum field capability and precision field measurements. The performance of the instrumentation with regard to precision, reliability, and operational needs for high volume testing will be described. Previous reports have described the measurement system used during development of the Saver magnets from which this system has evolved.

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Report on the Production Magnet Measurement System for the Fermilab Energy Saver Superconducting Dipoles and Quadrupoles

The Fermilab Magnet Test Facility performs testing of full scale SSC magnets on test stands capable of simulating the cryogenic environment of the SSC main ring One of these test stands, Stand 5, also has the ability to operate the magnet under test at temperatures from 18 K to 45 K with either supercritical helium or subcooled liquid, providing at least 25 W of refrigeration At least 50 g/s flow is available from 23 K to 45 K, whereas superfluid operation occurs with zero flow Among the special components designed to permit this variety of operating modes are heat exchangers for both forced flow of normal fluid and stagnant superfluid and special check valves which provide a thermal barrier at each large-diameter penetration to the superfluid space Other unique features include 10000 A current leads mounted in a separate, removable can for easy lead replacement if necessary, and the room-temperature vacuum pumping system with a 25 g/s capacity at 12 Torr Cooldown time from 45 K to 20 K is 15 hours Instrumentation to monitor and control the cryogenic conditions is provided

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A cryogenic test stand for full length SSC magnets with superfluid capability

Construction and testing of the components for the new Tevatron D0/B0 low beta insertion are nearly complete. The devices include superconducting cold iron quadrupoles utilizing a two-shell, cos2 theta coil geometry with a 7.6-cm aperture. The maximum design gradient is 1.41 T/cm at an operating current of 4832 A. They have the highest current density with the highest peak field on the winding of any quadrupole yet built. The authors summarize the quench performance and ramp rate sensitivity of the two-shell design and relate the performance characteristics to the relevant aspects of design and fabrication. >

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Quench performance of superconducting quadrupole magnets for the new Fermilab low beta insertion

Results are presented from tests of the first full length prototype SSC dipole magnet. The cryogenic behavior of the magnet during a slow cooldown to 4.5K and a slow warmup to room temperature has been measured. Magnetic field quality was measured at currents up to 2000 A. Averaged over the body field all harmonics with the exception of b 2 and b 8 are at or within the tolerances specified by the SSC Central Design Group. (The values of b 2 and b 8 result from known design and construction defects which will be corrected in later magnets.) Using an NMR probe the average body field strength is measured to be 10.283 G/A with point to point variations on the order of one part in 1000. Data are presented on quench behavior of the magnet up to 3500 A (approximately 55% of full field) including longitudinal and transverse velocities for the first 250 msec of the quench.

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Full length prototype SSC dipole test results

The 1500 W helium refrigerator system utilizes two oil-injected screw compressors staged to feed a liquid nitrogen pre-cooled cold box. Refrigeration is provided by two Sulzer TGL-22 magnetic/gas bearing turbines. The refrigerator feeds six magnet test stands via a 10,000 L dewar and subcooler equipped distribution box. The design of the controls has permitted the system to be routinely operated 24 hours a day, seven days a week with only five operators. It operated approximately 90% of the 4 1/2 years prior to a one-year shutdown in 1984, during which the compressor skid was moved. Scheduled maintenance, failures, repairs and holidays are about equal to the 10$ off time. The equipment described was used to test approximately 1200 superconducting magnets for the Fermilab accelerator ring.1 The seven year operating experience is presented as an equipment and technique review. Compressor hours currently exceed 42,000 and turbine hours exceed 39,000 each. Failure rates, causes, preventive maintenance, monitoring practices and equipment, and modifications are examined along with notes on some of the more successful applications of technique and equipment.

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Operational History Of Fermilab’s 1500 W Refrigerator Used for Energy Saver Magnet Production Testing

Operational history of Fermilab's 1500 W refrigerator used for energy saver magnet production testing

The cryogenic system of the Fermilab Magnet Test Facility has been used to provide cooling for the testting of approximately 1200 Energy Saver superconducting magnets. The system provides liquid helium, liquid nitrogen, gas purification, and vacuum support for six magnet test stands. It provides for simultaneous high current testing of two superconducting magnets and non-high current cold testing of two additional magnets. The cryogenic system has been in operation for about 32000 hours. The 1200 magnets have taken slightly more than three years to test.

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F. B. Johnson

Papers

Operational History Of Fermilab’s 1500 W Refrigerator Used for Energy Saver Magnet Production Testing

Operational history of Fermilab's 1500 W refrigerator used for energy saver magnet production testing

Cryogenic System for Production Testing and Measurement of Fermilab Energy Saver Superconducting Magnets