A small prototype of an active-target time projection chamber detector based on the gas electron multiplier(GEM) readout technique was designed and constructed.Simulation calculations were performed to analyze the ele...A small prototype of an active-target time projection chamber detector based on the gas electron multiplier(GEM) readout technique was designed and constructed.Simulation calculations were performed to analyze the electric field distribution and optimize the design.In particular,a guard ring installed above the GEM foil may play an important role in shaping the electric field in the gas vessel and improving the overall performance of the detector.The best results were obtained at a guard-ring voltage of-950 V.By using a collimated a-particle source,an energy resolution of 3.6–4.0 ke V can be achieved for deposited energies of 18–21 keV,respectively.A position resolution of less 0.2 mm was observed along the electron drift direction,whereas the resolution in the readout plane was approximately 0.45 mm.A time resolution of less than 20 ns was obtained.By using helium as the primary working gas as well as the target material,a t a elastic scattering events can be clearly imaged.展开更多
Molybdenum films were deposited on Corning 7059 glass substrates by DC magnetron sputtering with different working gas pressures and sputtering powers.The structure and morphology,residual stress and adhesion,resistiv...Molybdenum films were deposited on Corning 7059 glass substrates by DC magnetron sputtering with different working gas pressures and sputtering powers.The structure and morphology,residual stress and adhesion,resistivity and optical reflectance of the as-deposited Mo films were investigated.The results show that Mo films deposited with high working gas pressure and low sputtering power have a spherical surface morphology,small grain size,residual compressive stress and a good adhesion,high resistivity and low optical reflectance.With the working gas pressure decreased and the sputtering power increased,Mo films have elongated spindle-shape or diamond flake shape surface morphology,the grain size is increased,with residual stress changed from tensile to compressive,a poor adhesion,resistivity decreased and optical reflectance increased.展开更多
This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength r...This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Math number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements （optical and pneumatic）.展开更多
基金supported by the National Natural Science Foundation of China(Nos.11405005 and 11535004)the National Key R&D Program of China(No.2018YFA0404403)
文摘A small prototype of an active-target time projection chamber detector based on the gas electron multiplier(GEM) readout technique was designed and constructed.Simulation calculations were performed to analyze the electric field distribution and optimize the design.In particular,a guard ring installed above the GEM foil may play an important role in shaping the electric field in the gas vessel and improving the overall performance of the detector.The best results were obtained at a guard-ring voltage of-950 V.By using a collimated a-particle source,an energy resolution of 3.6–4.0 ke V can be achieved for deposited energies of 18–21 keV,respectively.A position resolution of less 0.2 mm was observed along the electron drift direction,whereas the resolution in the readout plane was approximately 0.45 mm.A time resolution of less than 20 ns was obtained.By using helium as the primary working gas as well as the target material,a t a elastic scattering events can be clearly imaged.
基金supported by the knowledge innovation program of the Chinese academy of sciences(Grant No.KGCX2-YW-347)
文摘Molybdenum films were deposited on Corning 7059 glass substrates by DC magnetron sputtering with different working gas pressures and sputtering powers.The structure and morphology,residual stress and adhesion,resistivity and optical reflectance of the as-deposited Mo films were investigated.The results show that Mo films deposited with high working gas pressure and low sputtering power have a spherical surface morphology,small grain size,residual compressive stress and a good adhesion,high resistivity and low optical reflectance.With the working gas pressure decreased and the sputtering power increased,Mo films have elongated spindle-shape or diamond flake shape surface morphology,the grain size is increased,with residual stress changed from tensile to compressive,a poor adhesion,resistivity decreased and optical reflectance increased.
基金the Technology Agency of the Czech Republic,which supported this research under grants No.TA03020277 and TH02020057Institutional support RVO61388998
文摘This study presents the comparison of aerodynamic performances of two successive designs of the root profiles for the ultra-long rotor blade equipped with a straight fir-tree dovetail. Since aerodynamic and strength requirements laid upon the root section design are contradictory, it is necessary to aerodynamically optimize the design within the limits given by the foremost strength requirements. The most limiting criterion of the static strength is the size of the blade cross-section, which is determined by the number of blades in a rotor and also by the shape and size of a blade dovetail. The aerodynamic design requires mainly the zero incidence angle at the inlet of a profile and in the ideal case ensures that the load does not exceed a limit load condition. Moreover, the typical root profile cascades are transonic with supersonic exit Math number, therefore, the shape of a suction side and a trailing edge has to respect transonic expansion of a working gas. In this paper, the two variants of root section profile cascades are compared and the aerodynamic qualities of both variants are verified using CFD simulation and two mutually independent experimental methods of measurements （optical and pneumatic）.
