The field‐angle dependence of the critical current in a REBa_(2)Cu_(3)O_(7) coated conductor has been measured over a fine range of temperatures from 15 K to 80 K.The particular sample is demonstrated to have a very ...The field‐angle dependence of the critical current in a REBa_(2)Cu_(3)O_(7) coated conductor has been measured over a fine range of temperatures from 15 K to 80 K.The particular sample is demonstrated to have a very low fraction of extrinsic planar defects by its near‐isotropic critical current at 77 K.At a representative magnetic field of 3 T we are able to track the emergence of the ab‐plane peak usually associated with intrinsic pinning and quantify its evolution with temperature by fitting to a maximum‐entropy function.We are also able to observe the evolution of dip and peak features in the angle dependence of the power‐law index n with decreasing temperature and show that a dip appearing at 65 K is supplanted by a sharper positive peak from 50 K.The combination of critical current and power‐law index temperature dependences shows the onset of intrinsic pinning at 50 K.展开更多
Applied-field magnetoplasmadynamic(AF-MPD)thrusters have been proposed as highly propellant-efficient thrusters for satellites and spacecraft.The electromagnets for these devices have only been reducible to practical ...Applied-field magnetoplasmadynamic(AF-MPD)thrusters have been proposed as highly propellant-efficient thrusters for satellites and spacecraft.The electromagnets for these devices have only been reducible to practical dimensions with the maturation of high-temperature superconductors.We report the development and ground testing of such a magnet which has been designed and constructed with the intention of deploying to the International Space Station and testing in orbit.The magnet is of dimensions suitable for accommodating a small thruster,will be cooled by a miniature space-compatible cryocooler and energized by a flux pump.It can generate a magnetic field of up to 760 mT operating at around 77 K in that configuration.A passive magnetic shield has been incorporated in order to comply with stray-field requirements of the ISS when operating at the target operational field of 300 mT.展开更多
基金supported by the Royal Society of New Zealand under Marsden Fund Grant VUW1805.
文摘The field‐angle dependence of the critical current in a REBa_(2)Cu_(3)O_(7) coated conductor has been measured over a fine range of temperatures from 15 K to 80 K.The particular sample is demonstrated to have a very low fraction of extrinsic planar defects by its near‐isotropic critical current at 77 K.At a representative magnetic field of 3 T we are able to track the emergence of the ab‐plane peak usually associated with intrinsic pinning and quantify its evolution with temperature by fitting to a maximum‐entropy function.We are also able to observe the evolution of dip and peak features in the angle dependence of the power‐law index n with decreasing temperature and show that a dip appearing at 65 K is supplanted by a sharper positive peak from 50 K.The combination of critical current and power‐law index temperature dependences shows the onset of intrinsic pinning at 50 K.
基金supported by the New Zealand Ministry of Business,Innovation and Employment under contract RTVU2003.
文摘Applied-field magnetoplasmadynamic(AF-MPD)thrusters have been proposed as highly propellant-efficient thrusters for satellites and spacecraft.The electromagnets for these devices have only been reducible to practical dimensions with the maturation of high-temperature superconductors.We report the development and ground testing of such a magnet which has been designed and constructed with the intention of deploying to the International Space Station and testing in orbit.The magnet is of dimensions suitable for accommodating a small thruster,will be cooled by a miniature space-compatible cryocooler and energized by a flux pump.It can generate a magnetic field of up to 760 mT operating at around 77 K in that configuration.A passive magnetic shield has been incorporated in order to comply with stray-field requirements of the ISS when operating at the target operational field of 300 mT.
