Insulation systems for superconducting fusion magnets based on cyanate ester blends

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Evaluation of inter-laminar shear strength of GFRP composed of bonded glass/polyimide tapes and cyanate-ester/epoxy blended resin for ITER TF coils AIP Conference Proceedings 1574, 154 (2014) ABSTRACTBecause of the double pancake design of the ITER TF coils the insulation will be applied in several steps. As a consequence, the conductor insulation as well as the pancake insulation will undergo multiple heat cycles in addition to the initial curing cycle. In particular the properties of the organic resin may be influenced, since its heat resistance is limited. Two identical types of sample consisting of wrapped R-glass / Kapton layers and vacuum impregnated with a cyanate ester / epoxy blend were prepared. The build-up of the reinforcement was identical for both insulation systems; however, one system was fabricated in two steps. In the first step only one half of the reinforcing layers was impregnated and cured. Afterwards the remaining layers were wrapped onto the already cured system, before the resulting system was impregnated and cured again. The mechanical properties were characterized prior to and after irradiation to fast neutron fluences of 1 and 2x10 22 m -2 (E>0.1 MeV) in tension and interlaminar shear at 77 K. In order to simulate the pulsed operation of ITER, tension-tension fatigue measurements were performed in the load controlled mode. The results do not show any evidence for reduced mechanical strength caused by the additional heat cycle.

Section: Ultimate Tensile Strengthmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Property Changes of Cyanate Ester∕epoxy Insulation Systems Caused by an Iter-Like Double Impregnation and by Reactor Irradiation

Prokopec¹,

Humer²,

Fillunger³

et al. 2010

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“…Humer et. al [2] demonstrated a reduction of the CE content to 40% only led to a 20-30% reduction of the static and dynamic material performance after exposure to a fast neutron fluence of 1×10 22 m -2 (E > 0.1MeV). Prokopec and his co-workers [3] also investigated the effect of the catalyst on the mechanical properties of glass fiber reinforced composites at 77K before and after neutron irradiation.…”

Section: Introductionmentioning

confidence: 99%

“…In the past few years, some advanced resin matrices with improved processing and radiation resistance properties, such as epoxy resins [1], were introduced into the fusion field. Recent studies [2][3][4] showed that cyanate ester (CE) has an excellent resistance against the gamma ray and neutron irradiation, and therefore being considered as a candidate insulation material for a fusion magnet. However, the CE is more expensive than traditional epoxy resins.…”

Section: Introductionmentioning

confidence: 99%

Rheological behavior and cryogenic properties of cyanate ester/epoxy insulation material for fusion superconducting magnet

et al. 2014

Evaluation of inter-laminar shear strength of GFRP composed of bonded glass/polyimide tapes and cyanateester/epoxy blended resin for ITER TF coils AIP Conference Proceedings 1574, 154 (2014) Abstract. In a Tokamak fusion reactor device like ITER, insulation materials for superconducting magnets are usually fabricated by a vacuum pressure impregnation (VPI) process. Thus these insulation materials must exhibit low viscosity, long working life as well as good radiation resistance. Previous studies have indicated that cyanate ester (CE) blended with epoxy has an excellent resistance against neutron irradiation which is expected to be a candidate insulation material for a fusion magnet. In this work, the rheological behavior of a CE/epoxy (CE/EP) blend containing 40% CE was investigated with non-isothermal and isothermal viscosity experiments. Furthermore, the cryogenic mechanical and electrical properties of the composite were evaluated in terms of interlaminar shear strength and electrical breakdown strength. The results showed that CE/epoxy blend had a very low viscosity and an exceptionally long processing life of about 4 days at 60 o C.

“…However, differences in the fabrication of samples, e.g. type of glass fibers, number of layers, made it difficult to find the best solution for ITER [1][2][3][4]. For this reason, comparable insulation samples were manufactured by Marti-Supratec, Switzerland, with exactly the same reinforcement and fabrication procedure, in order to check for the best radiation hardness and mechanical material performance.…”

Section: Introductionmentioning

confidence: 99%

Qualification of a cyanate ester epoxy blend supplied by Japanese industry for the ITER TF coil insulation

Prokopec¹,

Humer²,

Fillunger³

et al. 2012

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Radiation effect on interlaminar shear strength of the electric insulation system with cyanate ester and epoxy blended resin AIP Conference Proceedings 1435, 99 (2012) ABSTRACTDuring the last years, two cyanate ester epoxy blends supplied by European and US industry have been successfully qualified for the ITER TF coil insulation. The results of the qualification of a third CE blend supplied by Industrial Summit Technology (IST, Japan) will be presented in this paper. Sets of test samples were fabricated exactly under the same conditions as used before. The reinforcement of the composite consists of wrapped R-glass / polyimide tapes, which are vacuum pressure impregnated with the resin. The mechanical properties of this material were characterized prior to and after reactor irradiation to a fast neutron fluence of 2x10 22 m -2 (E>0.1 MeV), i.e. twice the ITER design fluence. Static and dynamic tensile as well as static short beam shear tests were carried out at 77 K. In addition, stress strain relations were recorded to determine the Young's modulus at room temperature and at 77 K. The results are compared in detail with the previously qualified materials from other suppliers.