Interaction of supersonic molecular beam with low-temperature plasma

The interaction between the supersonic molecular beam(SMB)and the low-temperature plasma is a critical issue for the diagnosis and fueling in the Tokamak device.In this work,the interaction process between the argon SMB and the argon plasma is studied by a high-speed camera based on the Linear Experimental Advanced Device(LEAD)in Southwestern Institute of Physics,China.It is found that the high-density SMB can extinct the plasma temporarily and change the distribution of the plasma density significantly,while the low-density SMB can hardly affect the distribution of plasma density.This can be used as an effective diagnostic technique to study the evolution of plasma density in the interaction between the SMB and plasma.Moreover,the related simulation based on this experiment is carried out to better understand the evolution of electron density and ion density in the interaction.The simulation results can be used to analyze and explain the experimental results well.

Timing analysis of the black hole candidate EXO 1846–031 with Insight-HXMT monitoring

We present the observational results from a detailed timing analysis of the black hole candidate EXO 1846-031 during its outburst in 2019 with the observations of Insight-HXMT,NICER and MAXI.This outburst can be classified roughly into four different states.Type-C quasi-periodic oscillations(QPOs)observed by NICER(about 0.1-6 Hz)and Insight-HXMT(about 0.7-8 Hz)are also reported in this work.Meanwhile,we study various physical quantities related to QPO frequency.The QPO rms-frequency relationship in the energy band 1-10 keV indicates that there is a turning pointing in frequency around2 Hz,which is similar to that of GRS 1915+105.A possible hypothesis for the relationship above may be related to the inclination of the source,which may require a high inclination to explain it.The relationships between QPO frequency and QPO rms,hardness,total fractional rms and count rate have also been found in other transient sources,which can indicate that the origin of type-C QPOs is non-thermal.

The influence of the Insight-HXMT/LE time response on timing analysis

The LE is the low energy telescope that is carried on Insight-HXMT.It uses swept charge devices(SCDs)to detect soft X-ray photons.LE’s time response is caused by the structure of the SCDs.With theoretical analysis and Monte Carlo simulations we discuss the influence of LE time response(LTR)on the timing analysis from three aspects:the power spectral density,the pulse profile and the time lag.After the LTR,the value of power spectral density monotonously decreases with the increasing frequency.The power spectral density of a sinusoidal signal reduces by a half at frequency 536 Hz.The corresponding frequency for quasi-periodic oscillation(QPO)signals is 458 Hz.The root mean square(RMS)of QPOs holds a similar behaviour.After the LTR,the centroid frequency and full width at half maxima(FWHM)of QPOs signals do not change.The LTR reduces the RMS of pulse profiles and shifts the pulse phase.In the time domain,the LTR only reduces the peak value of the cross-correlation function while it does not change the peak position;thus it will not affect the result of the time lag.When considering the time lag obtained from two instruments and one among them is LE,a 1.18 ms lag is expected caused by the LTR.The time lag calculated in the frequency domain is the same as that in the time domain.

Selective sintering of magnesia-calcia materials by utilizing hot spots during induction sintering process

Magnesia-calcia refractories are widely used in the production process of clean steel due to their excellent high-tem-perature stability,slag resistance and ability to purify molten steel.However,there are still problems such as difficult sintering and easy hydration.Magnesia-calcia materials with various calcium oxide contents were prepared by using induction sintering,and the sintering property combined with the hydration resistance of the materials was investigated.The experimental results showed that the magnesia-calcia materials prepared under induction field had higher density,microhardness and hydration resistance.In particular,the relative density of induction sintered magnesia-calcia materials with 50 mo1%CaO was greater than 98%,and the average grain size of CaO was 4.56μm,which was much larger than that of traditional sintered materials.In order to clarify the densification and microstructure evolution mechanism of the magnesia-calcia materials,the changes in temperature and magnetic field throughout the sintering process were analyzed by using finite element simulation.The results showed that the larger heating rate and higher sintering temperature under the induction sintering mode were beneficial to the rapid densification.In addition,the hot spots generated within the material due to the difference in high-temperature electric conductivity between MgO and CaO were the critical factor to realize selective sintering in MgO-CaO system,which provides a novel pathway to solve the problem of difficult sintering and control the microstructure of high-temperature composite material used in the field of high-purity steel smelting.

Highly reversible Zn anode enabled by anticatalytic carbon layer with suppressed hydrogen evolution

Aqueous zinc-ion batteries(AZIBs)have emerged as a promising high-efficiency energy storage system due to the high energy density,low-cost and environmental friendliness.However,the practical application of AZIBs is severely restricted by the challenges faced by the Zn anode,which include uncontrollable dendrite growth,corrosion and hydrogen evolution reaction.Herein,a simple and convenient physical vapor deposition(PVD)method is reported for fabricating uniform graphite as a protection layer on the surface of Zn anode.The high conductivity graphite layer on Zn anode(denoted as Zn@C)not only benefits the uniform distribution of the electric field,but also provides numerous Zn nucleation sites to regulate and navigate Zn-ion stripping/plating behaviors.Additionally,the graphite layer with a poor catalytic activity endows the Zn@C anode with a highly suppressed hydrogen evolution.Consequently,a hydrogen and dendrite free anode is achieved with artificial anticatalytic carbon layer on Zn anode,exhibiting a high reversibility and excellent cycling stability over 2600 h at the current density of 5 mA·cm^(-2)with a capacity of 2.5 mAh·cm^(-2)and longtime cycling stability for assembled full cells.This work strategically designs the properties of the artificial interface layer to effectively address various challenges simultaneously,which presents insights for the future development of high-performance rechargeable AZIBs.

Enhanced slag resistance and mechanical properties of magnesia castables with strontium carbonate addition

Magnesia castables have been widely used in metallurgical industries with the advantages of high refractoriness,non-polluting steel,and resistance to alkaline slag.Magnesia castables were prepared using strontium carbonate(SrCO_(3))as additive to enhance slag resistance and mechanical properties,and the influence of SrCO_(3) on the evolution of phases,microstructure and properties of magnesia castables sintered at different temperatures was clarified.The results show that,with the introduction of SrCO_(3)(lower than 3 wt.%),elastic modulus,mechanical strength,thermal shock resistance and densification of magnesia castables were significantly enhanced owing to the formation of needle-like Ca_(0.9)Sr_(0.1)MgSi_(2)O_(6) phase and liquid phase when sintering at high temperatures,and the introduced SrCO_(3) presented minor effects on the mechanical properties of castables for its highly structural stability below 1100℃.During the slag corrosion process,SrCO_(3) and SiO_(2) in castables reacted with Al^(3+)in molten slag to form SrAl_(2)SiO_(8) phase,resulting in the increased slag viscosity and suppressed continuing penetration.