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Laboratory, Japan

Kato Y.,Electromagnetic Systems Laboratory | Hasegawa H.,Cryogenic Systems Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2015

In Japan, regulations on low-frequency magnetic fields came into force. Initial regulations in 2011 applied to power equipment in general, but the scope of regulatory control was expanded in 2012 to cover track-side railway power equipment. Although railway vehicles are not included in the scope of the regulation at the moment, it thought that it is necessary to assess magnetic fields in railway vehicles. As such a series of studies have been launched to develop a method to measure and predict low-frequency magnetic fields in railway vehicles.


Mizuno K.,Cryogenic Systems Laboratory | Ogata M.,Cryogenic Systems Laboratory | Nagashima K.,Maglev Systems Technology Division
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2013

YBCO coated conductors attract attention because of their high critical current in high magnetic field conditions, hence calling for a suitable coil fabrication method. One of the critical problems associated with this process, however, is the negative impact on YBCO coil performance due to epoxy impregnation. Epoxy impregnation is an important technique to increase the mechanical strength and thermal conductivity of superconducting coils. However, the bonding strength of epoxy resin is stronger than the delamination strength of YBCO coated conductors in a certain direction. Therefore, thermal stress could damage epoxy impregnated YBCO coils. As a new impregnation material, we have focused on cyanoacrylate resin.


Mizuno K.,Cryogenic Systems Laboratory | Ogata M.,Cryogenic Systems Laboratory | Nagashima K.,Maglev Systems Technology Division
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2014

REBCO coated conductors have several characteristics which are superior to other superconductors. For example, its critical current is quite high even in the presence of high magnetic fields. Therefore, REBCO coated conductors make it possible to raise the operational temperature of superconductor applications. In turn, higher operational temperatures mean that the magnet cooling system consumes less energy. In the case of Maglev applications, it also means downsizing of the on-board power source and a reduction in the overall weight. A trial REBCO magnet that capable of generating 5 T (Tesla) was built. The magnets demonstrated that a magnetic flux density of 5 T was achievable at 45 K.


Miyazaki Y.,Cryogenic Systems Laboratory | Waki K.,Cryogenic Systems Laboratory | Arai Y.,Cryogenic Systems Laboratory | Mizuno K.,Cryogenic Systems Laboratory | And 2 more authors.
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2014

The aim of this study is to put a cooling technology using a magnetocaloric effect to practical use for air conditioners of railway vehicles in order to save energy. New magnetcaloric materials which have larger a magnetocaloric effect compared with Gd have been developed in the region of room temperature. Nevertheless, little discussion exists about how much the new materials affect the properties of a magnetocaloric cooling system. Therefore, the characteristics of the cooling system with Gd and La(Fe0.84Co 0.06Si0.10)13 have been studied experimentally and analytically.


Sugino M.,Cryogenic Systems Laboratory | Ogata M.,Cryogenic Systems Laboratory | Mizuno K.,Cryogenic Systems Laboratory | Hasegawa H.,Cryogenic Systems Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2015

Monitoring the temperature inside superconducting magnets is an effective way to detect failures and prevent damage to the magnet. It is possible to measure the multipoint temperatures with one optical fiber sensor thread. The sensor is suitable for measuring the temperature inside cryogenic equipment because of its low heat invasion and high voltage insulation in comparison with the resistance temperature sensors such as CERNOX, thermocouples, etc. However, there have been almost no cases where the optical fiber sensors have actually been used at cryogenic temperature. Investigations where therefore carried out into optical fiber temperature sensors that can be used at cryogenic temperature, to monitor the temperature inside superconducting magnets.

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