2013 Fiscal Year Final Research Report

Development of superconducting motor producing circular flow of superfluid helium

Research Project

Project/Area Number	24654108
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Condensed matter physics II
Research Institution	Osaka City University
Principal Investigator	YANO Hideo 大阪市立大学, 理学(系)研究科(研究院), 准教授 (70231652)
Project Period (FY)	2012-04-01 – 2014-03-31
Keywords	流体力学 / 低温物性 / 超流体 / 量子渦
Research Abstract	We report the results obtained in the present study as follows, for the purpose of developing a motor with a rotor working in superfluid helium. (1) We employ a brushless motor with a rotor separated from driving coils. A brushless motor requires a sensor of rotor position. We measured the features of some position sensors, finding that a sensor using induced voltages between ends of driving coils is appropriate for low temperature usage. (2) We have succeeded in developing a brushless motor working at low temperatures above -203 C (70 K), though the motor could not work below the temperature. (3) We find that a rotation loss increases with decreasing temperature. This is because magnetic hysteresis of the core material of the coils increases. (4) By measuring the drag force of an obstacle moving in superfluid helium, we find that the obstacle produces quantized vortices at a velocity above 100 mm/s.