Effects of Drag Force of Helium Gas on a Spinning Superconducting Rotor

A superconducting rotor with the high-speed rotation is driven by the torque generated from stator coils at low temperature in 4.2 K. It is necessary to fill the rotor housing with cold helium gas to remove the heat from the superconducting rotor to the support structure. However, it will bring the drag force from the gas, which has a negative effect on the rotating speed of the rotor. The drag torque of gas to act on the rotating rotor was calculated, and the experiment of deceleration of the rotating rotor was performed. The results show that the angular velocity is decaying with exponential function when the rotor rotates in the gas. It is necessary to calculate rotor deceleration at different gas pressures with different analysis methods.

[1]  I. Šimon,et al.  Forces acting on superconductors in magnetic fields , 1953 .

[2]  J. K. Fremerey.  Apparatus for Determination of Residual Drag Torque on Small Spinning Spheres in Magnetic Suspension , 1971 .

[3]  G. Schweitzer,et al.  Magnetic bearings : theory, design, and application to rotating machinery , 2009 .

[4]  C. Cui,et al.  Analysis of Magnetic-Supported Suspension Torque Acting on Superconducting Sphere Rotor , 2011, IEEE Transactions on Applied Superconductivity.

[5]  Hui Wang,et al.  Mass Imbalance Measurement of Incomplete Spherical Superconducting Rotor With Air Suspension , 2012, IEEE Transactions on Instrumentation and Measurement.

[6]  Gravity Probe.  Precision Electrostatic Suspension System for the Gravity Probe B Relativity Mission's Science Gyroscopes , 2003 .

[7]  J. Hull,et al.  Low rotational drag in high-temperature superconducting bearings , 1995, IEEE Transactions on Applied Superconductivity.

[8]  K. F. Schoch,et al.  A superconducting gyroscope for gimballed platform application. , 1967 .

[9]  Jianhua Liu,et al.  Analysis of the Driving Force of a Levitated Spherical Superconducting Rotor , 2012, IEEE Transactions on Applied Superconductivity.

[10]  T. Sugiura,et al.  Mechanical stability of a high-T/sub c/ superconducting levitation system , 1997, IEEE Transactions on Applied Superconductivity.

[11]  Edgar R. Canavan,et al.  Three-axis superconducting gravity gradiometer for sensitive gravity experiments , 2002 .

[12]  M. Strasik,et al.  Design, Fabrication, and Test of a 5-kWh/100-kW Flywheel Energy Storage Utilizing a High-Temperature Superconducting Bearing , 2007, IEEE Transactions on Applied Superconductivity.

[13]  J. Sengers,et al.  Kinetic theory of the drag force on objects in rarefied gas flows , 1986 .

[14]  Alexander Melin,et al.  Advanced instrumentation for extreme environments , 2013, IEEE Instrumentation & Measurement Magazine.

[15]  M. Ono,et al.  Japan's superconducting Maglev train , 2002 .

[16]  Chunyan Cui,et al.  A Fiber Optic Sensor Measurement System for a Levitated Sphere-Shaped Superconducting Rotor , 2010, IEEE Transactions on Applied Superconductivity.

[17]  Qiuliang Wang,et al.  Practical Design of Magnetostatic Structure Using Numerical Simulation , 2013 .

[18]  John R. Hull,et al.  Vertical and lateral forces between a permanent magnet and a high-temperature superconductor , 1999 .

[19]  Yi Li,et al.  Active Control Method for Passing Through Critical Speeds of Rotating Superconducting Rotor by Changing Stiffness of the Supports With Use of Electromagnetic Force , 2013, IEEE Transactions on Applied Superconductivity.

[20]  Jesse W. Beams,et al.  The Production of High Centrifugal Fields , 1946 .