The magnetic field design of a solenoid for the cold-cathode Penning ion source of a miniature neutron tube

A high-yield and beam-stable neutron tube can be applied in many fields.It is of great significance to the optimal external magnetic field intensity of the cold-cathode Penning ion source(PIS)and precisely controls the movement of deuterium(D),tritium(T)ions and electrons in the source of the neutron tubes.A cold-cathode PIS is designed based on the solenoidal magnetic field to obtain better uniformity of the magnetic field and higher yield of the neutron tube.The degree of magnetic field uniformity among the magnetic block,double magnetic rings and solenoidal ion sources is compared using finite element simulation methods.Using drift diffusion approximation and a magnetic field coupling method,the plasma distribution of hydrogen and the relationship between plasma density and magnetic field intensity at 0.06 Pa pressure and a solenoid magnetic field are obtained.The results show that the solenoidal ion source has the most uniform magnetic field distribution.The optimum magnetic field strength of about 0.1 T is obtained in the ion source at an excitation voltage of 1 V.The maximum average number density of monatomic hydrogen ions(H+)is 1×108 m−3,and an ion-beam current of about 14.51μA is formed under the−5000 V extraction field.The study of the solenoidal magnetic field contributes to the understanding of the particle dynamics within the PIS and provides a reference for the further improvement of the source performance of the neutron tube in the future.

A magnetic field strategy to porous Pt-Ni nanoparticles with predominant (111) facets for enhanced electrocatalytic oxygen reduction

For the first time, we developed porous Pt-Ni alloying nanoparticles with predominant(111) facets under intense magnetic fields. Electrochemical analysis revealed that the Pt-Ni alloying nanoparticles obtained at 2 Tesla exhibited a superior catalytic activity and durability for oxygen reduction reaction. This work demonstrated that the imposition of intense magnetic field could be considered as a new approach for developing efficient alloying electrocatalysts with preferential facets.

EFFECT OF THE MAGNETIC FIELD ON THE PULSATILE FLOW THROUGH A RIGID TUBE

This study presents the effect of the magnetic field with constant intensity on the pulsatile flow through a rigid tube. Basing on the experimental results, the influence of the magnetic field on the blood viscosity is considered The analytic solution of the pulsatile flow through a rigid tube under constant magnetic field intensitier and the effect of the magnetic field on the velocity distribution, flow and impedance in a rigid tube are given. this investigation is valuable for understanding the influence of the magnetic field on the blood circulation.

Magnetization and magnetic phase diagrams of a spin-1/2 ferrimagnetic diamond chain at low temperature

We used the Jordan-Wigner transform and the invariant eigenoperator method to study the magnetic phase diagram and the magnetization curve of the spin-1/2 alternating ferrimagnetic diamond chain in an external magnetic field at finite temperature.The magnetization versus external magnetic field curve exhibits a 1/3 magnetization plateau at absolute zero and finite temperatures,and the width of the 1/3 magnetization plateau was modulated by tuning the temperature and the exchange interactions.Three critical magnetic field intensities H_(CB),H_(CE)and H_(CS) were obtained,in which the H_(CB) and H_(CE)correspond to the appearance and disappearance of the 1/3 magnetization plateau,respectively,and the higher H_(CS) correspond to the appearance of fully polarized magnetization plateau of the system.The energies of elementary excitation hω_(σ,k)(σ=1,2,3)present the extrema of zero at the three critical magnetic fields at 0 K,i.e.,[hω_(3,k)(H_(CB)]_(min)=0,[hω_(2,k)(H_(CE)]_(max)=0 and[hω_(2,k)(H_(CS)]_(min)=0,and the magnetic phase diagram of magnetic field versus different exchange interactions at 0 K was established by the above relationships.According to the relationships between the system’s magnetization curve at finite temperatures and the critical magnetic field intensities,the magnetic field-temperature phase diagram was drawn.It was observed that if the magnetic phase diagram shows a three-phase critical point,which is intersected by the ferrimagnetic phase,the ferrimagnetic plateau phase,and the Luttinger liquid phase,the disappearance of the 1/3 magnetization plateau would inevitably occur.However,the 1/3 magnetization plateau would not disappear without the three-phase critical point.The appearance of the 1/3 magnetization plateau in the low temperature region is the macroscopic manifestations of quantum effect.

Effects of Roasting Pretreatment in Intense Magnetic Field on Phase Transition and Digestion Performance of Diasporic Bauxite

This paper investigates the changes of phase and apparent morphology under the combined effects of an intense magnetic field and temperature field.The effect of different roasting conditions on the digestion performance of roasted ore is also studied.The results indicate that roasting pretreatment under high magnetic fields can change the microstructure and digestion performance of bauxite.The Al phase changed faster of high iron bauxite than that of low iron bauxite.The digestion performance of low iron bauxite improved significantly through roasting pretreatment in intense magnetic field. But the digestion performance of bauxite get worse with the iron content in bauxite increase,because the high iron content of bauxite lead the shielding effect of magnetic field and make the crystal structure of bauxite stably,the surface area or low iron bauxite increased obviously during pretreatment.The optimal pretreatment condition of low iron bauxite is roasting temperature of 550℃,roasting time of 60min and magnetic field intensity of 6T,while for the high iron is roasting temperature of 500℃,roasting time of 60min and magnetic field intensity of 9T.

Effects of different magnetic flux densities on microstructure and magnetic properties of molecular-beam-vapor-deposited nanocrystalline Fee4Ni36 thin films

The nanocrystalline Fe64Ni36 thin films were prepared by molecular-beam- vapor deposition under different magnetic flux densities. The microstructure and magnetic properties of thin films were examined by AFM, TEM, HRTEM and VSM. The results show that with the increase of magnetic flux densities, the changing trend of the average particle size is the same as the coercive force except 6 T. Under 6 T condition, the thin film became the mixture of bcc and fcc phases, which leads to slight increase of the coercive force. In addition, the HRTEM result shows the short-range ordered clusters （embryos） or nucleation rate of thin films increase with increasing magnetic flux densities.