We present a study of magnetic transport and radiation properties during compression of a magnetized laboratory plasma.A theta pinch is used to produce a magnetized plasma column undergoing radial implosion,with plasm...We present a study of magnetic transport and radiation properties during compression of a magnetized laboratory plasma.A theta pinch is used to produce a magnetized plasma column undergoing radial implosion,with plasma parameters comprehensively measured through diverse diagnostic techniques.High-resolution observations show the implosion progressing through three stages:compression,expansion,and recompression.An anomalous demagnetization phenomenon is observed during the first compression stage,wherein the magnetic field at the plasma center is depleted as the density increases.We reveal the demagnetization mechanism and formulate a straightforward criterion for determining its occurrence,through analysis based on extended-magnetohydrodynamics theory and a generalized Ohm’s law.Additionally,we quantitatively evaluate the radiation losses and magnetic field variations during the two compression stages,providing experimental evidence that magnetic transport can influence the radiation properties by altering the plasma hydrodynamics.Furthermore,extrapolated results using our findings reveal direct relevance to magnetized inertial confinement fusion,space,and astrophysical plasma scenarios.展开更多
We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced,magnetized plasma(1–3×10^(18)cm^(-3),1–15 eV)in the context of a laboratory astrophysics experiment under a c...We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced,magnetized plasma(1–3×10^(18)cm^(-3),1–15 eV)in the context of a laboratory astrophysics experiment under a controlled magneticfield up to 20T.Nitrogen lines(NII)in the visible range were used to diagnose the magneticfield and plasma conditions.This was performed by coupling our data with(563–574 nm)the Stark–Zeeman line-shape code PPPB.The excellent agreement between experiment and simulations paves the way for a non-intrusive experimental platform to get time-resolved measurements of the local magneticfield in laboratory plasmas.展开更多
This research presents a new method to boost the efficiency of evaporative coolers by integrating magnetized water and a heat exchanger.Magnetized water,known for its high evaporation rate and reduced surface tension,...This research presents a new method to boost the efficiency of evaporative coolers by integrating magnetized water and a heat exchanger.Magnetized water,known for its high evaporation rate and reduced surface tension,offers a promising way to enhance air cooler performance.Additionally,the advanced heat exchanger both improves air cooling capacity and controls humidity levels.Aloni 100 L,a locally manufactured evaporative cooling system,and tap water were used in experiments.Tap water was magnetized using recycled magnets extracted from computer hard drives.Twenty-six magnets meticulously arranged within rectangular grooves,each with a minimum strength of 0.5 to 1T,were used tomagnetize tapwater.Our experiments showa significant rise in cooling efficiency,with magnetized water increasing from 70.62%to 91.43%.In a similar vein,adding the heat exchanger leads to a significant improvement,raising the cooling efficiency from 69.44%to 93.96%.Furthermore,the combined use of magnetized water and a heat exchanger results in exceptional performance,increasing cooling efficiencies by 29.5%and 35.3%compared to using only magnetized water or only a heat exchanger,respectively.This study also explores the largely untapped potential of magnetized water,providing valuable insights into its effects on water properties and its broader applications in various fields.These findings represent a significant advancement in air cooling technology and pave the way for more energy-efficient and sustainable solutions.展开更多
Controlling terahertz(THz)polarization with high stability and tunability is essential for achieving further progress in ultrafast spectroscopy,structured-light manipulation,and quantum information processing.Here,we ...Controlling terahertz(THz)polarization with high stability and tunability is essential for achieving further progress in ultrafast spectroscopy,structured-light manipulation,and quantum information processing.Here,we propose a magnetized plasma platform for dynamic THz polarization control by exploiting the intrinsic birefringence between extraordinary and ordinary modes.We identify a strong-magnetization,zero-group-velocity-mismatch regime where the two modes share matched group velocities while retaining finite phase birefringence,enabling robust,phase-stable spin angular momentum control.By tuning the plasma length and magnetic field,we realize programmable phase retardation and demonstrate universal single-qubit gates through parameterized unitary operations.Full-wave particle-in-cell simulations validate high-fidelity polarization transformations across the Poincarésphere and demonstrate the potential for generating structured vector beams under spatially varying magnetic fields.The platform offers ultrafast response,resilience to extreme THz intensities,and in situ tunability,positioning magnetized plasmas as a versatile and damage-resilient medium for next-generation THz polarization control and structured-wave applications.展开更多
The electromagnetic wave propagations and their coupling characteristics in magnetized plasma near the antenna of ion cyclotron range of frequencies(ICRF)is studied based on self-developed 3DFEM-IA code.This code effe...The electromagnetic wave propagations and their coupling characteristics in magnetized plasma near the antenna of ion cyclotron range of frequencies(ICRF)is studied based on self-developed 3DFEM-IA code.This code effectively resolves the three-dimensional(3D)geometry and the electromagnetic field using the finite element method.Our findings reveal that the distributions of electromagnetic fields and energy flow density significantly depend on the antenna phases,surface current density on the antenna straps,and background plasma density.Notably,the non-uniform surface current density on the antenna straps,resulting from the presence of induced currents,contributes to a reduction in coupling power within the edge plasma.Furthermore,the calculated coupling impedance increases with plasma density,corroborating well with experimental measurements.展开更多
For the magnetized complex plasma,dependences of modified Yukawa potential on the gov-erning parameters,viz.,mass ratio md/mi,number ratio nd/ne0,charge magnitude Q/e,and temperature ratio Te/Ti are investigated.It is...For the magnetized complex plasma,dependences of modified Yukawa potential on the gov-erning parameters,viz.,mass ratio md/mi,number ratio nd/ne0,charge magnitude Q/e,and temperature ratio Te/Ti are investigated.It is found that md/mi,nd/ne0 and Q/e contribute to the coupling strength of the system,and Te/Ti contributes to the shielding cloud surrounding the charged dust particles.Further analysis shows that the modified Yukawa potential depends on Te/Ti.The consequent structure changes of the system are discussed based on the Langevin dynamics simulation.It is found that the variation of Ham-iltonian contributes to the equilibrium structure of the system.展开更多
The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-per...The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-performance spintronic memory and computing applications.Here,we report the development of the PMA superlattice[Pt/Co/W]_(n)that can be sputtered-deposited on commercial oxidized silicon substrates and has giant SOTs,strong uniaxial PMA of≈9.2 Merg/cm^(3),and rigid macrospin performance.The damping-like and field-like SOTs of the[Pt/Co/W]_(n)superlattices exhibit a linear increase with the repeat number n and reach the giant values of 225%and-33%(two orders of magnitude greater than that in clean-limit Pt)at n=12,respectively.The damping-like SOT is also of the opposite sign and much greater in magnitude than the field-like SOT,regardless of the number n.These results clarify that the spin current that generates SOTs in the[Pt/Co/W]_(n)superlattices arises predominantly from the spin Hall effect rather than bulk Rashba spin splitting,providing a unified understanding of the SOTs in these superlattices.We also demonstrate deterministic switching in thickerthan-50-nm PMA[Pt/Co/W]_(12)superlattices at a low current density.This work establishes the[Pt/Co/W]_(n)superlattice as a compelling material candidate for ultra-fast,low-power,long-retention nonvolatile spintronic memory and computing technologies.展开更多
With Welsh Onion seeds employed as materials, effects of magnetized water on seed Germination were studied. The results showed the treatment of magnetized water soaking for 4 h promoted water absorption rate and amyla...With Welsh Onion seeds employed as materials, effects of magnetized water on seed Germination were studied. The results showed the treatment of magnetized water soaking for 4 h promoted water absorption rate and amylase ac- tivities of seeds significantly, which accelerated the transformation process of en- dosperm starch to soluble sugar, resulting in emergence of 36 hours in advance under low temperature condition. Germination rate and germination potential of magnetized water soaking were higher than the contrast by 6.7% and 10.0%, which helped cultivate vigorous seedling.展开更多
Tomato seeds （Lycopersicon esculentum L. Mill. cv. zhongshu No. 6） were treated by magnetized plasma before being sown to investigate its effect on the growth and yield of tomatoes. Biochemical analysis showed that ...Tomato seeds （Lycopersicon esculentum L. Mill. cv. zhongshu No. 6） were treated by magnetized plasma before being sown to investigate its effect on the growth and yield of tomatoes. Biochemical analysis showed that dehydrogenase activity increased with the increase of the current but decreased when the current was higher than 1.5 A. The activities of peroxidase （POD） isoenzyme changed in the same pattern. There was no difference in germination percentage between treatments and control, which were carried out in laboratory conditions. However, significant （c~ = 0.01） difference was observed in germination percentage in the pot experiment. In the pot experiment, the sprouting rate for the treatment with a 1.5 A current was 32.75%, whereas the untreated was only 4.75% on the eleventh day. Germination time is more than one day earlier than the control. The 1.5 A treatment increased the tomato yield by 20.7%.展开更多
The piecewise linear recursive convolution （PLRC） finite-different time-domain （FDTD） method greatly improves accuracy over the original recursive convolution （RC） FDTD approach but retains its speed and efficie...The piecewise linear recursive convolution （PLRC） finite-different time-domain （FDTD） method greatly improves accuracy over the original recursive convolution （RC） FDTD approach but retains its speed and efficiency advantages. A PLRC-FDTD formulation for magnetized plasma which incorporates both anisotropy and frequency dispersion at the same time is presented, enabled the transient analysis of magnetized plasma media. The technique is illustrated by numerical simulations the reflection and transmission coefficients through a magnetized plasma layer. The results show that the PLRC-FDTD method has significantly improved the accuracy over the original RC method.展开更多
For the magnetized fluidized bed(MFB)with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles,the magnetically induced segregation between these two kinds of particles occurs at high magnetic fi...For the magnetized fluidized bed(MFB)with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles,the magnetically induced segregation between these two kinds of particles occurs at high magnetic field intensities(H),leading to the deterioration of the fluidization quality.The critical intensity(H_(ms))above which such segregation commences varies with the gas velocity(U_g).This work focuses on establishing a segregation model to theoretically derive the H_(ms)–U_g relationship.In a magnetic field,the magnetizable particles form agglomerates.The magnetically induced segregation in essence refers to the size segregation of the binary mixture of agglomerates and nonmagnetizable particles.Consequently,the segregation model was established in two steps:first,the size of agglomerates(d_A)was calculated by the force balance model;then,the H_(ms)–U_g relationship was obtained by substituting the expression of d_Ainto the basic size segregation model for binary mixtures.As per the force balance model,the cohesive and collision forces were 1_2 orders of magnitude greater than the other forces exerted on the agglomerates.Therefore,the balance between these two forces largely determined d_A.The calculated d_A increased with increasing H and decreasing U_g,agreeing qualitatively with the experimental observation.The calculated H_(ms)–U_ g relationship agreed reasonably with the experimental data,indicating that the present segregation model could predict well the segregation behavior in the MFB with the binary mixture.展开更多
We conduct an electron magnetohydrodynamics magnetic reconnection experiment with guide-field in our Keda linear magnetized plasma device, in which two pulsed currents with the same direction are conducted in parallel...We conduct an electron magnetohydrodynamics magnetic reconnection experiment with guide-field in our Keda linear magnetized plasma device, in which two pulsed currents with the same direction are conducted in parallel with the axial direction of the main chamber of the device using two long aluminum sticks. After approximately 5μs, an X-type magnetic field line topology is formed at the center of the chamber. With the formation of the X-type topology of magnetic field lines, we can also find the rapid increase of the current and ratio of the common flux to the private flux in this area. Additionally, a reduction in the plasma density and the plasma density concentration along one pair of separatrices can also be found.展开更多
The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are invest...The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are investigated. A linear dispersion relation is obtained. The numerical results show that the external magnetized field, fast ions and nonadiabatic dust charge fluctuation have strong influence on the frequency and the damping of wave.展开更多
In this paper, non-equilibrium ignition conditions for magnetized cylindrical deuterium–tritium plasma in the presence of an axial magnetic field have been investigated. It is expected that temperature imbalance betw...In this paper, non-equilibrium ignition conditions for magnetized cylindrical deuterium–tritium plasma in the presence of an axial magnetic field have been investigated. It is expected that temperature imbalance between ions and electrons as well as the axial magnetic field will relax the threshold of ignition conditions.Therefore, ignition conditions for this model are derived numerically involving the energy balance equation at the stagnation point. It has been derived using parametric space including electron and ion temperature(T_e, T_i), areal density(q R), and seed magnetic field-dependent free parameters of B/q, mB, and BR. For B/ρ < 10~6 G cm^3 g^(-1),mB < 4 × 10~4 G cm g^(-1), and BR <3 × 10~5 G cm, the minimum fuel areal density exceeds between ρR >0.002 g cm^(-2), ρR> 0.25 g cm^(-2), and ρR > 0.02 g cm^(-2),respectively. The practical equilibrium conditions also addressed which is in good agreement with the corresponding one-temperature magnetized mode proposed in previous studies. Moreover, it has been shown that the typical criterion of BR ≥(6.13–4.64) × 10~5 G cm would be expectable. It is also confirmed that the minimum product of areal density times fuel temperature in equilibrium model is located in the range of T = 6–8 keV for all these free parameters, depending on the magnitude of the magnetic field. This is the entry point for the non-equilibrium model consistent with equilibrium model.展开更多
Effect of critical beam radius on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive nonlinearity forms the main core of present work. To investigate propagation dynamics...Effect of critical beam radius on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive nonlinearity forms the main core of present work. To investigate propagation dynamics of cosh-Gaussian laser beams in collisionless magnetized plasma, well established parabolic equation approach under WKB and paraxial approximations is employed. Our study is crucially pivoted on the concept of critical curve and subsequent determination of numerical interval for decentered parameter to sustain the competition between diffraction and self-focusing during the propagation of laser beam. Additionally, in the present study an interesting feature in the self-focusing region of the critical curve has been attempted for different values of decentered parameter.展开更多
A wakefield driven by a short intense laser pulse in a perpendicularly magnetized underdense plasma is studied analytically and numerically for both weakly relativistic and highly relativistic situations. Owing to the...A wakefield driven by a short intense laser pulse in a perpendicularly magnetized underdense plasma is studied analytically and numerically for both weakly relativistic and highly relativistic situations. Owing to the DC magnetic field, a transverse component of the electric fields associated with the wakefield appears, while the longitudinal wave is not greatly affected by the magnetic field up to 22 Tesla. Moreover, the scaling law of the transverse field versus the longitudinal field is derived. One-dimensional particle-in-cell simulation results confirm the analytical results. Wakefield transmission through the plasma-vacuum boundary, where electromagnetic emission into vacuum occurs, is also investigated numerically. These results are useful for the generation of terahertz radiation and the diagnosis of laser wakefields.展开更多
The secondary electron emission(SEE) and inclined magnetic field are typical features at the channel wall of the Hall thruster acceleration region(AR), and the characteristics of the magnetized sheath have a significa...The secondary electron emission(SEE) and inclined magnetic field are typical features at the channel wall of the Hall thruster acceleration region(AR), and the characteristics of the magnetized sheath have a significant effect on the radial potential distribution, ion radial acceleration and wall erosion. In this work, the magnetohydrodynamics model is used to study the characteristics of the magnetized sheath with SEE in the AR of Hall thruster. The electrons are assumed to obey non-extensive distribution, the ions and secondary electrons are magnetized.Based on the Sagdeev potential, the modified Bohm criterion is derived, and the influences of the non-extensive parameter and magnetic field on the AR sheath structure and parameters are discussed. Results show that, with the decrease of the parameter q, the high-energy electron leads to an increase of the potential drop in the sheath, and the sheath thickness expands accordingly,the kinetic energy rises when ions reach the wall, which can aggravate the wall erosion.Increasing the magnetic field inclination angle in the AR of the Hall thruster, the Lorenz force along the x direction acting as a resistance decelerating ions becomes larger which can reduce the wall erosion, while the strength of magnetic field in the AR has little effect on Bohm criterion and wall potential. The propellant type also has a certain effect on the values of wall potential,secondary electron number density and sheath thickness.展开更多
Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to it...Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm2 to 6 A/cm2 in pulsed mode within pulse length 5-20 ms. A 10 cm diameter, 2 m long plasma column with density 10is m-3 to 1019 m3 and electron temperature Te --~ 3-7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper.展开更多
The piecewise linear recursive convolution （PLRC） finite-different time-domain （FDTD） method improves accuracy over the original recursive convolution （RC） FDTD approach and current density convolution （JEC） b...The piecewise linear recursive convolution （PLRC） finite-different time-domain （FDTD） method improves accuracy over the original recursive convolution （RC） FDTD approach and current density convolution （JEC） but retains their advantages in speed and efficiency. This paper describes a revised piecewise linear recursive convolution PLRC-FDTD formulation for magnetized plasma which incorporates both anisotropy and frequency dispersion at the same time, enabling the transient analysis of magnetized plasma media. The technique is illustrated by numerical simulations of the reflection and transmission coefficients through a magnetized plasma layer. The results show that the revised PLRC-FDTD method has improved the accuracy over the original RC FDTD method and JEC FDTD method.展开更多
A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast （-230 ns）, 55 kA current pulse into ...A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast （-230 ns）, 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device （ICCD） detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.展开更多
基金the State Key Development Program for Basic Research of China(Grant No.2022YFA1602503)the National Natural Science Foundation of China(Grant Nos.12120101005 and 12205247)
文摘We present a study of magnetic transport and radiation properties during compression of a magnetized laboratory plasma.A theta pinch is used to produce a magnetized plasma column undergoing radial implosion,with plasma parameters comprehensively measured through diverse diagnostic techniques.High-resolution observations show the implosion progressing through three stages:compression,expansion,and recompression.An anomalous demagnetization phenomenon is observed during the first compression stage,wherein the magnetic field at the plasma center is depleted as the density increases.We reveal the demagnetization mechanism and formulate a straightforward criterion for determining its occurrence,through analysis based on extended-magnetohydrodynamics theory and a generalized Ohm’s law.Additionally,we quantitatively evaluate the radiation losses and magnetic field variations during the two compression stages,providing experimental evidence that magnetic transport can influence the radiation properties by altering the plasma hydrodynamics.Furthermore,extrapolated results using our findings reveal direct relevance to magnetized inertial confinement fusion,space,and astrophysical plasma scenarios.
基金supported by grants managed by l’Agence Nationale de la Recherche under the Investissements d’Avenir programs Grant Nos. ANR-18-EURE-0014, ANR-10-LABX-0039-PALM, and ANR-22-CE30-0044supported by grants from Japan Society for the Promotion of Science (JSPS) KAKENHI (Grant No. 23K20038)+2 种基金JSPS Core-to-Core program (Grant No. JPJSCCA20230003)carried out within the framework of the EUROfusion Consortium, funded by the European Union via the Euratom Research and Training Programme (Grant Agreement No. 101052200-EUROfusion)operated within the framework of the Enabling Research Project No. AWP24-ENR-IFE.02.CEA-01 “Magnetized ICF”
文摘We report the observation of Zeeman splitting in multiple spectral lines emitted by a laser-produced,magnetized plasma(1–3×10^(18)cm^(-3),1–15 eV)in the context of a laboratory astrophysics experiment under a controlled magneticfield up to 20T.Nitrogen lines(NII)in the visible range were used to diagnose the magneticfield and plasma conditions.This was performed by coupling our data with(563–574 nm)the Stark–Zeeman line-shape code PPPB.The excellent agreement between experiment and simulations paves the way for a non-intrusive experimental platform to get time-resolved measurements of the local magneticfield in laboratory plasmas.
文摘This research presents a new method to boost the efficiency of evaporative coolers by integrating magnetized water and a heat exchanger.Magnetized water,known for its high evaporation rate and reduced surface tension,offers a promising way to enhance air cooler performance.Additionally,the advanced heat exchanger both improves air cooling capacity and controls humidity levels.Aloni 100 L,a locally manufactured evaporative cooling system,and tap water were used in experiments.Tap water was magnetized using recycled magnets extracted from computer hard drives.Twenty-six magnets meticulously arranged within rectangular grooves,each with a minimum strength of 0.5 to 1T,were used tomagnetize tapwater.Our experiments showa significant rise in cooling efficiency,with magnetized water increasing from 70.62%to 91.43%.In a similar vein,adding the heat exchanger leads to a significant improvement,raising the cooling efficiency from 69.44%to 93.96%.Furthermore,the combined use of magnetized water and a heat exchanger results in exceptional performance,increasing cooling efficiencies by 29.5%and 35.3%compared to using only magnetized water or only a heat exchanger,respectively.This study also explores the largely untapped potential of magnetized water,providing valuable insights into its effects on water properties and its broader applications in various fields.These findings represent a significant advancement in air cooling technology and pave the way for more energy-efficient and sustainable solutions.
基金supported by the National Natural Science Foundation of China (Grant Nos. 12175058 and 11921006)the National Grand Instrument Project (No. 2019YFF01014402)the Beijing Distinguished Young Scientist Program and National Grand Instrument Project No. SQ2019YFF01014400
文摘Controlling terahertz(THz)polarization with high stability and tunability is essential for achieving further progress in ultrafast spectroscopy,structured-light manipulation,and quantum information processing.Here,we propose a magnetized plasma platform for dynamic THz polarization control by exploiting the intrinsic birefringence between extraordinary and ordinary modes.We identify a strong-magnetization,zero-group-velocity-mismatch regime where the two modes share matched group velocities while retaining finite phase birefringence,enabling robust,phase-stable spin angular momentum control.By tuning the plasma length and magnetic field,we realize programmable phase retardation and demonstrate universal single-qubit gates through parameterized unitary operations.Full-wave particle-in-cell simulations validate high-fidelity polarization transformations across the Poincarésphere and demonstrate the potential for generating structured vector beams under spatially varying magnetic fields.The platform offers ultrafast response,resilience to extreme THz intensities,and in situ tunability,positioning magnetized plasmas as a versatile and damage-resilient medium for next-generation THz polarization control and structured-wave applications.
基金Project supported by the National MCF Energy Research and Development Program(Grant No.2022YFE03190100)the National Natural Science Foundation of China(Grant Nos.12422513,12105035,and U21A20438)the Xiaomi Young Talents Program。
文摘The electromagnetic wave propagations and their coupling characteristics in magnetized plasma near the antenna of ion cyclotron range of frequencies(ICRF)is studied based on self-developed 3DFEM-IA code.This code effectively resolves the three-dimensional(3D)geometry and the electromagnetic field using the finite element method.Our findings reveal that the distributions of electromagnetic fields and energy flow density significantly depend on the antenna phases,surface current density on the antenna straps,and background plasma density.Notably,the non-uniform surface current density on the antenna straps,resulting from the presence of induced currents,contributes to a reduction in coupling power within the edge plasma.Furthermore,the calculated coupling impedance increases with plasma density,corroborating well with experimental measurements.
基金Supported by National Natural Science Foundation of China(12275354,11805272)the College Students'Innovative Entrepreneurial Training Plan Program of Civil Aviation University of China(202210059080)。
文摘For the magnetized complex plasma,dependences of modified Yukawa potential on the gov-erning parameters,viz.,mass ratio md/mi,number ratio nd/ne0,charge magnitude Q/e,and temperature ratio Te/Ti are investigated.It is found that md/mi,nd/ne0 and Q/e contribute to the coupling strength of the system,and Te/Ti contributes to the shielding cloud surrounding the charged dust particles.Further analysis shows that the modified Yukawa potential depends on Te/Ti.The consequent structure changes of the system are discussed based on the Langevin dynamics simulation.It is found that the variation of Ham-iltonian contributes to the equilibrium structure of the system.
基金supported by the National Key Research and Development Program of China(Grant No.2022YFA1204000)the Beijing National Natural Science Foundation(Grant No.Z230006)the National Natural Science Foundation of China(Grant Nos.12304155 and 12274405).
文摘The development of magnetic heterostructures with strong perpendicular magnetic anisotropy(PMA),strong spin-orbit torques(SOTs),low impedance,and good integration compatibility at the same time is central for high-performance spintronic memory and computing applications.Here,we report the development of the PMA superlattice[Pt/Co/W]_(n)that can be sputtered-deposited on commercial oxidized silicon substrates and has giant SOTs,strong uniaxial PMA of≈9.2 Merg/cm^(3),and rigid macrospin performance.The damping-like and field-like SOTs of the[Pt/Co/W]_(n)superlattices exhibit a linear increase with the repeat number n and reach the giant values of 225%and-33%(two orders of magnitude greater than that in clean-limit Pt)at n=12,respectively.The damping-like SOT is also of the opposite sign and much greater in magnitude than the field-like SOT,regardless of the number n.These results clarify that the spin current that generates SOTs in the[Pt/Co/W]_(n)superlattices arises predominantly from the spin Hall effect rather than bulk Rashba spin splitting,providing a unified understanding of the SOTs in these superlattices.We also demonstrate deterministic switching in thickerthan-50-nm PMA[Pt/Co/W]_(12)superlattices at a low current density.This work establishes the[Pt/Co/W]_(n)superlattice as a compelling material candidate for ultra-fast,low-power,long-retention nonvolatile spintronic memory and computing technologies.
基金Supported by China Spark Program for Science and Technology(2011GA740072)Shandong Provincial Soft Scientific Research Project(2015RKC35001)Shandong Provincial Agricultural High-quality Seed Engineering(2016LZGC019)~~
文摘With Welsh Onion seeds employed as materials, effects of magnetized water on seed Germination were studied. The results showed the treatment of magnetized water soaking for 4 h promoted water absorption rate and amylase ac- tivities of seeds significantly, which accelerated the transformation process of en- dosperm starch to soluble sugar, resulting in emergence of 36 hours in advance under low temperature condition. Germination rate and germination potential of magnetized water soaking were higher than the contrast by 6.7% and 10.0%, which helped cultivate vigorous seedling.
基金National Natural Science Foundation of China (No. 5017700) and the Natural Science Foundation ofShanxi Province (No. 20051078)
文摘Tomato seeds （Lycopersicon esculentum L. Mill. cv. zhongshu No. 6） were treated by magnetized plasma before being sown to investigate its effect on the growth and yield of tomatoes. Biochemical analysis showed that dehydrogenase activity increased with the increase of the current but decreased when the current was higher than 1.5 A. The activities of peroxidase （POD） isoenzyme changed in the same pattern. There was no difference in germination percentage between treatments and control, which were carried out in laboratory conditions. However, significant （c~ = 0.01） difference was observed in germination percentage in the pot experiment. In the pot experiment, the sprouting rate for the treatment with a 1.5 A current was 32.75%, whereas the untreated was only 4.75% on the eleventh day. Germination time is more than one day earlier than the control. The 1.5 A treatment increased the tomato yield by 20.7%.
基金The project was supported by the National Natural Science Foundation of China (60471002) and the Jiangxi ProvincialNatural Science Foundation (0412014)
文摘The piecewise linear recursive convolution （PLRC） finite-different time-domain （FDTD） method greatly improves accuracy over the original recursive convolution （RC） FDTD approach but retains its speed and efficiency advantages. A PLRC-FDTD formulation for magnetized plasma which incorporates both anisotropy and frequency dispersion at the same time is presented, enabled the transient analysis of magnetized plasma media. The technique is illustrated by numerical simulations the reflection and transmission coefficients through a magnetized plasma layer. The results show that the PLRC-FDTD method has significantly improved the accuracy over the original RC method.
基金Supported by the National Natural Science Foundation of China(21325628)the Major Research Plan of the National Natural Science Foundation of China(91334108)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(YZ201641)
文摘For the magnetized fluidized bed(MFB)with the binary mixture of Geldart-B magnetizable and nonmagnetizable particles,the magnetically induced segregation between these two kinds of particles occurs at high magnetic field intensities(H),leading to the deterioration of the fluidization quality.The critical intensity(H_(ms))above which such segregation commences varies with the gas velocity(U_g).This work focuses on establishing a segregation model to theoretically derive the H_(ms)–U_g relationship.In a magnetic field,the magnetizable particles form agglomerates.The magnetically induced segregation in essence refers to the size segregation of the binary mixture of agglomerates and nonmagnetizable particles.Consequently,the segregation model was established in two steps:first,the size of agglomerates(d_A)was calculated by the force balance model;then,the H_(ms)–U_g relationship was obtained by substituting the expression of d_Ainto the basic size segregation model for binary mixtures.As per the force balance model,the cohesive and collision forces were 1_2 orders of magnitude greater than the other forces exerted on the agglomerates.Therefore,the balance between these two forces largely determined d_A.The calculated d_A increased with increasing H and decreasing U_g,agreeing qualitatively with the experimental observation.The calculated H_(ms)–U_ g relationship agreed reasonably with the experimental data,indicating that the present segregation model could predict well the segregation behavior in the MFB with the binary mixture.
基金Supported by the National Natural Science Foundation of China under Grant Nos 41331067 and 41527804the Key Research Program of Frontier Sciences of Chinese Academy of Sciences under Grant No QYZDJ-SSW-DQC010the Fundamental Research Funds for the Central Universities
文摘We conduct an electron magnetohydrodynamics magnetic reconnection experiment with guide-field in our Keda linear magnetized plasma device, in which two pulsed currents with the same direction are conducted in parallel with the axial direction of the main chamber of the device using two long aluminum sticks. After approximately 5μs, an X-type magnetic field line topology is formed at the center of the chamber. With the formation of the X-type topology of magnetic field lines, we can also find the rapid increase of the current and ratio of the common flux to the private flux in this area. Additionally, a reduction in the plasma density and the plasma density concentration along one pair of separatrices can also be found.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10475066 and 10347006）.
文摘The effects of external magnetized field and nonadiabatic dust charge fluctuation on instability of wave incorporating the nonthermally distributed ions and the temperatures of ion and dust in dusty plasmas are investigated. A linear dispersion relation is obtained. The numerical results show that the external magnetized field, fast ions and nonadiabatic dust charge fluctuation have strong influence on the frequency and the damping of wave.
文摘In this paper, non-equilibrium ignition conditions for magnetized cylindrical deuterium–tritium plasma in the presence of an axial magnetic field have been investigated. It is expected that temperature imbalance between ions and electrons as well as the axial magnetic field will relax the threshold of ignition conditions.Therefore, ignition conditions for this model are derived numerically involving the energy balance equation at the stagnation point. It has been derived using parametric space including electron and ion temperature(T_e, T_i), areal density(q R), and seed magnetic field-dependent free parameters of B/q, mB, and BR. For B/ρ < 10~6 G cm^3 g^(-1),mB < 4 × 10~4 G cm g^(-1), and BR <3 × 10~5 G cm, the minimum fuel areal density exceeds between ρR >0.002 g cm^(-2), ρR> 0.25 g cm^(-2), and ρR > 0.02 g cm^(-2),respectively. The practical equilibrium conditions also addressed which is in good agreement with the corresponding one-temperature magnetized mode proposed in previous studies. Moreover, it has been shown that the typical criterion of BR ≥(6.13–4.64) × 10~5 G cm would be expectable. It is also confirmed that the minimum product of areal density times fuel temperature in equilibrium model is located in the range of T = 6–8 keV for all these free parameters, depending on the magnitude of the magnetic field. This is the entry point for the non-equilibrium model consistent with equilibrium model.
文摘Effect of critical beam radius on self-focusing of cosh-Gaussian laser beams in collisionless magnetized plasma under ponderomotive nonlinearity forms the main core of present work. To investigate propagation dynamics of cosh-Gaussian laser beams in collisionless magnetized plasma, well established parabolic equation approach under WKB and paraxial approximations is employed. Our study is crucially pivoted on the concept of critical curve and subsequent determination of numerical interval for decentered parameter to sustain the competition between diffraction and self-focusing during the propagation of laser beam. Additionally, in the present study an interesting feature in the self-focusing region of the critical curve has been attempted for different values of decentered parameter.
基金supported in part by National Natural Science Foundation of China(Nos.10734130,10925421,11075105)the National Basic Research Program of China(Nos.2007CB310406,2009GB105002)
文摘A wakefield driven by a short intense laser pulse in a perpendicularly magnetized underdense plasma is studied analytically and numerically for both weakly relativistic and highly relativistic situations. Owing to the DC magnetic field, a transverse component of the electric fields associated with the wakefield appears, while the longitudinal wave is not greatly affected by the magnetic field up to 22 Tesla. Moreover, the scaling law of the transverse field versus the longitudinal field is derived. One-dimensional particle-in-cell simulation results confirm the analytical results. Wakefield transmission through the plasma-vacuum boundary, where electromagnetic emission into vacuum occurs, is also investigated numerically. These results are useful for the generation of terahertz radiation and the diagnosis of laser wakefields.
基金supported by National Natural Science Foundation of China (Nos. 11975062, 11605021, 11975088)the China Postdoctoral Science Foundation (No. 2017M621120)。
文摘The secondary electron emission(SEE) and inclined magnetic field are typical features at the channel wall of the Hall thruster acceleration region(AR), and the characteristics of the magnetized sheath have a significant effect on the radial potential distribution, ion radial acceleration and wall erosion. In this work, the magnetohydrodynamics model is used to study the characteristics of the magnetized sheath with SEE in the AR of Hall thruster. The electrons are assumed to obey non-extensive distribution, the ions and secondary electrons are magnetized.Based on the Sagdeev potential, the modified Bohm criterion is derived, and the influences of the non-extensive parameter and magnetic field on the AR sheath structure and parameters are discussed. Results show that, with the decrease of the parameter q, the high-energy electron leads to an increase of the potential drop in the sheath, and the sheath thickness expands accordingly,the kinetic energy rises when ions reach the wall, which can aggravate the wall erosion.Increasing the magnetic field inclination angle in the AR of the Hall thruster, the Lorenz force along the x direction acting as a resistance decelerating ions becomes larger which can reduce the wall erosion, while the strength of magnetic field in the AR has little effect on Bohm criterion and wall potential. The propellant type also has a certain effect on the values of wall potential,secondary electron number density and sheath thickness.
基金supported by National Natural Science Foundation of China(No.11275200)
文摘Plasma source is the most important part of the laboratory plasma platform for fundamental plasma experimental research. Barium oxide coated cathode plasma source is well recognized as an effective technique due to its high electron emission current. An indirectly heated oxide coated cathode plasma source has been constructed on a linear magnetized plasma device. The electron emission current density can reach 2 A/cm2 to 6 A/cm2 in pulsed mode within pulse length 5-20 ms. A 10 cm diameter, 2 m long plasma column with density 10is m-3 to 1019 m3 and electron temperature Te --~ 3-7 eV is produced. The spatial uniformity of the emission ability is less than 4% and the discharge reproducibility is better than 97%. With a wide range of the plasma parameters, this kind of plasma source provides great flexibility for many basic plasma investigations. The detail of construction and initial characterization of oxide coated cathode are described in this paper.
基金National Natural Science Foundation of China (No. 60471002) and the Natural Science Foundation ofJiangxi Province (No. 0412014)
文摘The piecewise linear recursive convolution （PLRC） finite-different time-domain （FDTD） method improves accuracy over the original recursive convolution （RC） FDTD approach and current density convolution （JEC） but retains their advantages in speed and efficiency. This paper describes a revised piecewise linear recursive convolution PLRC-FDTD formulation for magnetized plasma which incorporates both anisotropy and frequency dispersion at the same time, enabling the transient analysis of magnetized plasma media. The technique is illustrated by numerical simulations of the reflection and transmission coefficients through a magnetized plasma layer. The results show that the revised PLRC-FDTD method has improved the accuracy over the original RC FDTD method and JEC FDTD method.
基金supported by National Natural Science Foundation of China(Nos.11105147,11375197 and 11175179)the Ministry of Education of China(No.IRT1190)
文摘A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast （-230 ns）, 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device （ICCD） detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.
