A diamond-shaped shock wave was created in a helium arcjet plasma. Visi- ble/ultraviolet emission spectroscopy was used to investigate the condition for the formation of stable shocks and to determine characteristics ...A diamond-shaped shock wave was created in a helium arcjet plasma. Visi- ble/ultraviolet emission spectroscopy was used to investigate the condition for the formation of stable shocks and to determine characteristics of the plasma. Dependence of the position of the shock front on the gas pressure in the expansion region was investigated. It was found that the shock wave arises from the collision of plasma particles and residual neutral atoms in that region. Continuum and line spectra of neutral helium were measured, from which the electron temper- atures were derived. The electron density was deduced from the Inglis-Teller limit of the He I 2p3p-3d3D series. The temperature and density were found to have almost constant values of 0.2 eV and 8.5x 1013 cm-3, respectively, across the shock front.展开更多
Despite repeated proposals to uillize superconducting magnets in space since at least the 1970s,examples of their use remain scant.One of the technical challenges is to maintai n sui table cryogenic temperatures on a ...Despite repeated proposals to uillize superconducting magnets in space since at least the 1970s,examples of their use remain scant.One of the technical challenges is to maintai n sui table cryogenic temperatures on a spacecraft.This challenge can be alleviated by the use of flux pumps to reduce the required cryogenic cooling power needed to energize the superconducting magnet.This paper describes the design and initial test results of the flux pump to fulfll the requirements of the Haki mission that will operate a high-temperature supercon-ducting magnet on an extemal platorm of the International Space Station.A transfomer based,self-recti fier architecture was chosen for the flux pump.An effecive circuit model used to deign its electromagnetc properties and fini teelement modelling used in its mechanical and thermal design.Liquid nitrogen tests were used to demonstrate that the electrical performance of the flux pump meets requirements.Higher-fidelity tests using flight-like copies of the hardware and software were undertaken and validated the thermal modelling.These tests also featured the continuous operation of the flux pump in a conduction-cooled setting for over 100 h,relecting an inherent reliability of this technology.Whilst further testing and flight qualification remains to be completed,we anticipate an on-orbit demonstration of this flux pump technology in April 2025.Such a demonstration will signal a maturing of this emergi ng superconducting technology for both in-space and terrestrial applications.展开更多
文摘A diamond-shaped shock wave was created in a helium arcjet plasma. Visi- ble/ultraviolet emission spectroscopy was used to investigate the condition for the formation of stable shocks and to determine characteristics of the plasma. Dependence of the position of the shock front on the gas pressure in the expansion region was investigated. It was found that the shock wave arises from the collision of plasma particles and residual neutral atoms in that region. Continuum and line spectra of neutral helium were measured, from which the electron temper- atures were derived. The electron density was deduced from the Inglis-Teller limit of the He I 2p3p-3d3D series. The temperature and density were found to have almost constant values of 0.2 eV and 8.5x 1013 cm-3, respectively, across the shock front.
基金funded by the New Zealand Ministry of Business,Innovation and Employment through the project‘High Magnetic Field Electric Propulsion for Space’,contract number RTVU2003the Strategic Science Investment Fund‘Advanced Energy Technology Plat-forms’under Contract RTVU2004.
文摘Despite repeated proposals to uillize superconducting magnets in space since at least the 1970s,examples of their use remain scant.One of the technical challenges is to maintai n sui table cryogenic temperatures on a spacecraft.This challenge can be alleviated by the use of flux pumps to reduce the required cryogenic cooling power needed to energize the superconducting magnet.This paper describes the design and initial test results of the flux pump to fulfll the requirements of the Haki mission that will operate a high-temperature supercon-ducting magnet on an extemal platorm of the International Space Station.A transfomer based,self-recti fier architecture was chosen for the flux pump.An effecive circuit model used to deign its electromagnetc properties and fini teelement modelling used in its mechanical and thermal design.Liquid nitrogen tests were used to demonstrate that the electrical performance of the flux pump meets requirements.Higher-fidelity tests using flight-like copies of the hardware and software were undertaken and validated the thermal modelling.These tests also featured the continuous operation of the flux pump in a conduction-cooled setting for over 100 h,relecting an inherent reliability of this technology.Whilst further testing and flight qualification remains to be completed,we anticipate an on-orbit demonstration of this flux pump technology in April 2025.Such a demonstration will signal a maturing of this emergi ng superconducting technology for both in-space and terrestrial applications.
