摘要 :
To generate arbitrary shape magnetic field waveforms for advanced scientific research,a reconfigurable pulsed high magnetic field facility(PHMFF)was developed at Wuhan National Pulsed High Magnetic Field Centre(WHMFC).First,the ba...
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To generate arbitrary shape magnetic field waveforms for advanced scientific research,a reconfigurable pulsed high magnetic field facility(PHMFF)was developed at Wuhan National Pulsed High Magnetic Field Centre(WHMFC).First,the basic elements of PHMFF are introduced,and a ternary physical model composed of energy storage unit,magnet,transmission circuits and other auxiliary units is summarised to describe various magnetic field systems.Second,in order to realise the reconfiguration of magnetic field systems based on detailed elements,the control system with the ability of dynamic construction and control sequence reconfiguration is designed.On this basis,the PHMFF has been realised and various magnetic field systems are constructed to produce arbitrary shape magnetic field waveforms,such as half‐sine,ultra‐high,flat‐top and repetitive field pulses,which not only enhances the capability and efficiency of PHMFF,but also makes more scientific research possible in pulsed magnetic fields.So far,a peak magnetic field of 94.8 T,a flat‐top magnetic field of 64 T/10 ms and a repetitive magnetic field waveform of 20 T/60 Hz have been achieved,and some experiments and studies on the physical properties of materials have been carried out at WHMFC.
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摘要 :
Using a self-made pulse magnetic field heat treatment equipment with low or medium intensi-ty,the tempering process of high speed steel W6Mo5Cr4V2 was investigated.It was foundthat the secondary hardening process and the transform...
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Using a self-made pulse magnetic field heat treatment equipment with low or medium intensi-ty,the tempering process of high speed steel W6Mo5Cr4V2 was investigated.It was foundthat the secondary hardening process and the transformation of retained austenite for the steelwere accelerated by the pulse magnetic field,and the tempering period could be reduced tohalf of the original.It was shown by the analyses of X-ray and eletron microscopy that theprecipitation of carbides becomes more homogeneous and dispersive,and the tetragonality ofmartensite increases obviousely,which causes the improvement of hardness and red-hardnessfor the steel.It was confirmed that the service life of tools as centre bits,screw taps andpunches for nuts could be increased by 0.4 to 1.4 times by the tempering in magnetic field.
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This paper describes the magnetic field measurement system for pulsed magnets in SSRF.The system consists of magnetic probes,analog active integrator,oscilloscope,stepper motor and a controller.An application program based on LabV...
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This paper describes the magnetic field measurement system for pulsed magnets in SSRF.The system consists of magnetic probes,analog active integrator,oscilloscope,stepper motor and a controller.An application program based on LabVIEW has been developed as main control unit.After the magnetic field mapping of a septum magnet prototype,it is verified that the test results accord with the results of theoretical calculation and computer simuladon.
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Dielectric barrier discharge (DBD) for SO2 removal from indoor air is investigated.In order to improve the removal efficiency,two novel methods are combined in this paper,namely by applying a pulsed driving voltage with nanosecond...
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Dielectric barrier discharge (DBD) for SO2 removal from indoor air is investigated.In order to improve the removal efficiency,two novel methods are combined in this paper,namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field.For SO2 removal efficiency,different matches of electric field and magnetic field are discussed.And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared.It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted,and electrical field and magnetic field should be applied in an appropriate match.
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An application of magnetic field to the nanosecond pulse corona discharge is investigated.A cylinder reactor with different corona electodes is set up for experimental study.A manetic field with its direction perpendicular to the ...
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An application of magnetic field to the nanosecond pulse corona discharge is investigated.A cylinder reactor with different corona electodes is set up for experimental study.A manetic field with its direction perpendicular to the corona discharge is applied.Different discharge images are taken under single nanosecond pulse with a high sensitive UV-visible light imagine recorder.Experimental results show that with a cross magnetic field the nanosecond out the magnetic field. The results may lead to a possibility to apply a cross magnetic field on nanosecond pulse corona discharge for getting higher desulfurization effciency.
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The characteristics of hot electrons produced by p-polarized femtosecond laser-solid interactions are studied. The experimental results show that the outgoing electrons are mainly emitted in three directions: along the target surf...
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The characteristics of hot electrons produced by p-polarized femtosecond laser-solid interactions are studied. The experimental results show that the outgoing electrons are mainly emitted in three directions: along the target surface, the normal direction and the laser backward direction. The electrons flowing along the target surface are due to the confinement of the electrostatic field and the surface magnetic field, while the electrons in the normal direction due to the resonant absorption.
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The application of pulse magnetic field to metal solidification is an advanced technique which can remarkably refine solidification structure. In this paper, the effect of pulse magnetic field on solidification structure,mechanica...
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The application of pulse magnetic field to metal solidification is an advanced technique which can remarkably refine solidification structure. In this paper, the effect of pulse magnetic field on solidification structure,mechanical properties and conductivity of pure copper was experimentally investigated. The results showed that the solidification structure transformed from coarse columnar crystal to fine globular crystal with increasing pulse voltage.Increasing pulse voltage also improved the tensile strength. However, with the increase of pulse voltage, the elongation and electrical resistivity firstly decreased, then increased when the pulse voltage beyond a critical value. Moreover,in some conditions, pulse magnetic field can simultaneously improve the conductivity and mechanical property of pure copper.
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Non-magnetic semiconductor materials and their devices have attracted wide attention since they are usually prone to exhibit large positive magnetoresistance(MR)effect in a low static magnetic field environment at room temperature...
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Non-magnetic semiconductor materials and their devices have attracted wide attention since they are usually prone to exhibit large positive magnetoresistance(MR)effect in a low static magnetic field environment at room temperature.However,how to obtain a large room-temperature negative MR effect in them remains to be studied.In this paper,by designing an Au/n-Ge:Sb/Au device with metal electrodes located on identical side,we observe an obvious room-temperature negative MR effect in a specific 50 T pulsed high magnetic field direction environment,but not in a static low magnetic field environment.Through the analysis of the experimental measurement of the Hall effect results and bipolar transport theory,we propose that this unconventional negative MR effect is mainly related to the charge accumulation on the surface of the device under the modulation of the stronger Lorentz force provided by the pulsed high magnetic field.This theoretical analytical model is further confirmed by regulating the geometry size of the device.Our work sheds light on the development of novel magnetic sensing,magnetic logic and other devices based on non-magnetic semiconductors operating in pulsed high magnetic field environment.
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The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obt...
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The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.
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