Development of a liquid hydrogen transfer pump system with MgB2 wires

Abstract

An electric pump composed of an MgB2 motor is combined with superconducting level sensors using thin CuNi-sheathed MgB2 wires to transfer liquid hydrogen. An impeller is attached to the lower end of a rotating shaft on the MgB2 motor and covered with an outer casing to form a centrifugal pump. Then, the MgB2 motor and impeller are placed vertically inside a cryostat with an infill of liquid hydrogen. A glass Dewar vessel is prepared to receive the liquid hydrogen transferred from the cryostat containing the MgB2 motor. The MgB2 sensors are used not only to detect the level of liquid hydrogen but also to control the electric pump on the basis of their pre-estimated calibration curves. By using the assembled pump system, the liquid hydrogen is successfully transferred from the cryostat to the glass Dewar vessel via a transfer tube. / 21Highlights: A pump system composed of an MgB 2 motor and MgB 2 level sensors was constructed. The centrifugal pump was formed by attaching an aluminum impeller to the motor. A glass Dewar vessel receives the liquid hydrogen from a cryostat for the pump. The MgB 2 sensors were used to detect the liquid level and to control the motor. Transfer of liquid hydrogen was successfully carried out with the pump system. liquid hydrogen but also to control the electric pump on the basis of their pre-estimated calibration curves. By using the assembled pump system, the liquid hydrogen is successfully transferred from the cryostat to the glass Dewar vessel via a transfer tube.

Low temperature decomposition of metal borohydride drives autogenous synthesis of MgB2

“…The rapid development of MgB 2 superconducting wires [1][2][3][4] reflects exceptional potential for industrial applications [5,6] as well as physical properties [7] that suit typical wire drawing processes [3,8]. Recent attention is focussed on optimising wire properties to achieve critical current density, J c , at higher magnetic fields than conventional low temperature superconductors to maximise industrial applications [9][10][11][12]. Exemplar applications for which MgB 2 wire quality is an important criterion include low field magnets for imaging [13] and energy storage [14], high energy physics [6] and fusion reactors [15,16].…”

Energization test apparatus of HTS coils cooled by liquid hydrogen and manufacture of split-type REBCO external field coil

“…The development of immersion-cooled hightemperature superconducting (HTS) devices using LH2 as the coolant has begun [3]. However, owing to hydrogen's wide flammability range (4-75%) and the challenge of hydrogen embrittlement in materials, there have been limited instances of research and development concerning LH2-cooled superconducting devices [4,5]. We developed and operated an LH2 test apparatus to understand the basic boiling heat-transfer characteristics of LH2 as a coolant [6], evaluate the transport-current characteristics of LH2-cooled superconducting wires [7], develop elemental technologies for LH2cooled superconducting devices and cooling systems, and establish explosion-proof designs and safety technologies.…”

Vortex pinning properties and microstructure of MgB2heavily doped with titanium group elements

“…No weak coupling between the MgB 2 grains [2,3] enables an untextured sample with high critical current density, J c , over 10 5 A cm −2 at 20 K in the self-field [4]. However, the J c value of MgB 2 is known to strongly deteriorate in magnetic fields [4], which must be improved for practical superconducting wire and bulk applications such as a magnet [5][6][7][8], motor [9] and generator [10]. Chemical doping or substitution is one of the solutions to improve the vortex pinning properties of MgB 2 .…”