No-insulation (NI) REBCO magnets have many advantages. They are self-protecting, therefore do not need quench detection and protection which can be very challenging in a high Tc superconducting magnet. Moreover, by removing insulation and allowing thinner copper stabilizer, NI REBCO magnets have significantly higher engineering current density and higher mechanical strength. On the other hand, NI REBCO magnets have drawbacks of long magnet charging time and high field-ramp-loss. In principle, these drawbacks can be mitigated by managing the turn-to-turn contact resistivity (Rc). Evidently the first step toward managing Rc is to establish a reliable method of accurate Rc measurement. In this paper, we present experimental Rc measurements of REBCO tapes as a function of mechanical load up to 144 MPa and load cycles up to 14 times. We found that Rc is in the range of 26-100 µΩ -cm 2 ; it decreases with increasing pressure, and gradually increases with number of load cycles. The results are discussed in the framework of Holm's electric contact theory.

Structure and magnetic properties of multi-walled carbon nanotubes modified with iron Low Temp.

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Insulation in a high field superconducting magnet plays a critical role. For high field magnets using coated conductor, insulation faces a few special challenges. In order to maximize the engineering current density, the conductor insulation has to be very thin (e.g.). In addition to required mechanical and dielectric integrity under high stresses at cryogenic temperatures, the temperature during insulation process needs to be significantly lower than 200where degradation of coated conductor may occur.In this paper, we will first review the options for coated conductor insulation. Then we present our UV cured epoxy insulation system developed for insulating coated conductors. This reel-toreel system is able to coat YBCO tapes or co-winding steel tapes with 10 UV cured epoxy. The coating has good dielectric property and shows no cracking or de-bonding in liquid nitrogen under up to 0.75% of applied bending or tensile strains. In addition, a silica sol gel based ceramic coating system has been developed for coating oxides on steel co-winding tapes, taking advantage of excellent thermal properties of the oxides. Some issues of both UV cured epoxy and the sol gel insulation coatings will be discussed.

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Goddard, Dowson, Longfield and Wright, The measurement o/sti~ness in human joints 229 ConclusionsThe small scale capillary viscometer has proved to be a versatile and convenient instrument to use for the determination of the flow curves of small quantities of polymer melts. The piston speed can be rapidly and accurately set over a speed range of I000:1. The melt pressure is measued directly above the capillary, which has the advantage over measuring the pressure in the piston face, or the thrust on the piston, m that the frictional forces in the piston, and the pressure drop in a long barrel do not have to be allowed for. Rapid pressure changes such as those that oeeur in oscillatory flow, can be detected (the transducer response time is 3 #s). Temperature control of the melt is within 0.5 deg. C., and temperature changes can be rapid because of the low thermal capacity of the barrel, The total cost of the instrument was about s 1,500. ~u,mTa~a~'yA small scale capillary viscometer that is capable of measuring the flow curves of 2 3 gins of molten polymer over the shear rate range 0.4 sec 1 to 20,000 see -I is described. A piezo electric crystal pressure transducer is used to measure the pressure directly above the capillary. Flow curves are given for anionic polystyrenes and polyethylene fractions, and it is shown that the viscosities measured agree with determinations in a cone and plate viscometer. Zusammen/assungEs wird ein maBstgblich kleines Kapillarviskosimeter ffir 2-3 g gesehmolzener Polymere besehrieben, das die DurchfluBkurve in Abhhmgigkeit vom Scherkoeffizienten im Bereich yon 0,4 sec -~ bis 20000 sec -x bestimmt. Verwendet wird ein piezoelektrischer KristallDruckaufnehmer, der den Druek genau fiber der Kapillare miBt. Angeffihrt werden DurchfluBkurven ffir anionische Polystyrole und Poly~thylenanteile. Es wird gezeigt, dab die gemessenen Zs mit denen yon Kegel-und Plattendichtemessern fihereinstimmen. Re/erences

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