Diffusion Region Research Articles

Evidence of a Magnetic Null in Electron‐Only Reconnection

AbstractMagnetic nulls are traditionally suggested as main points where energy dissipation occurs during reconnection. Such nulls have been widely observed in the diffusion region of standard reconnection following a two‐fluid picture, but have never been investigated in the thin current sheet of electron‐only reconnection. Recently, an electron‐only reconnection event was observed by the Magnetospheric Multiscale (MMS) mission in Earth's magnetosheath. The small separation of MMS spacecraft (∼7 km) provides a good opportunity to examine whether magnetic nulls exist in electron‐only reconnection. By utilizing the First‐Order Taylor Expansion method, we find a radial null in this event. Moreover, such nulls degenerate into X‐type nulls inside a reconnecting current sheet, suggesting that it's quasi 2D structure. By reconstructing the topology of this null, we can also estimate the reconnection rate of this electron‐only reconnection event and find it's time‐varying, suggesting it's an unsteady process. Our results are useful to further understand the process of electron‐only reconnection.

Investigation of the Catalytic Properties of Aluminum Oxide (Al2O3) and Pyrite (FeS2) Using Thermodynamic and Kinetic Parameters.

The kinetics of anthracene hydrogenation was studied using the method of equilibrium kinetic analysis. To determine the diffusion-kinetic characteristics, anthracene hydrogenation was performed at different temperatures (648 K, 673 K, 698 K), at a hydrogen pressure of 3 MPa in the presence of a mixture of pyrite (FeS2) and aluminum oxide (Al2O3) taken at a ratio of 1:1. Chromatographic analysis of anthracene hydrogenation products showed the presence of 9,10-dihydroanthracene (DHA), 1,2,3,4-tetrahydroanthracene (THA), methylnaphthalene (MN), naphthalene (H) and other unidentified compounds. In order to preserve the material balance, a total hydrogenation reaction of anthracene, up to 9,10-dihydroanthracene, was proposed as characterized by the highest rate in the presence of pyrite-based catalysts and aluminum oxide. Calculations of the degrees of rotation of anthracene, reaction constants, and Gibbs energy have shown that with increasing temperature, the reaction becomes more thermodynamically advantageous. Based on the obtained data, Arrhenius dependences were constructed, which made it possible to calculate the activation energies of direct (39.4 kJ/mol) and reverse (13.04 kJ/mol) reactions. Thus, based on the calculations performed, it was found that the process of anthracene hydrogenation in the presence of a mixture of pyrite and aluminum oxide proceeds mainly in the diffusion region.

Observation and Reconstruction of Electron Vortex in Reconnection Outflow

AbstractOn 27 January 2017, Magnetospheric Multi‐Scale observed a series of electron vortexes, which are driven by the electron Kelvin‐Helmholtz (K‐H) instability in the reconnection outflow at terrestrial magnetopause. We find the electron vorticity can reach above 200 s−1 inside the vortexes, which is comparable to the strong vorticity events in the electron diffusion region. Using the First‐Order Taylor Expansion for Velocity field method, we further reconstruct the 3D topology of two electron vortexes and find one vortex is converging while another vortex is diverging. Interestingly, enhancement of electron temperature was observed in the diverging vortex but not in the converging vortex, indicating electron dynamics is related to the vortex topology. Our study suggests that electron K‐H vortexes formed by the intense electron shear flow in the reconnection outflow have different types of topologies and will help us better understand the reconnection picture at the terrestrial magnetopause.

Performance assessment on DES/DDES method for transient flow in a centrifugal turbomachine model subjects to rotor-stator interaction

We present an assessment of the performances of the detached eddy simulation (DES) and delayed detached eddy simulation (DDES) approaches in resolving the transient flow in a system of a centrifugal impeller and a vaned diffuser which is strongly destabilized by the rotor-stator interaction (RSI). The numerical results obtained by the DES and DDES approaches are compared against that from an independent large-eddy simulation (LES) investigation and that of a vaneless diffuser model. The time-averaged and fluctuating velocity, the nonlinear primary momentum transport term, and the two-point correlation of fluctuating pressure in the impeller, diffuser, and vaneless region are analyzed. The numerical results reveal that the diffuser vanes substantially perturb the flow inside the impeller, especially at the impeller outlet. The DDES approach cannot resolve the multi-scale flow structures in the vaneless region. The DES approach produces a time-averaged velocity field that is more consistent with the LES approach, and the DDES approach performs better for the reversed flow. For the transient behaviors, the DES approach is more sensitive to weak fluctuation, and for the pressure fluctuation in the impeller where the RSI significantly perturbs. The DDES approach gives a consistent two-point correlation of fluctuating pressure with the LES approach, while the DES approach could not give an accurate prediction.

Secondary Reconnection Between Interlinked Flux Tubes Driven by Magnetic Reconnection With a Short X‐Line

AbstractA three‐dimensional particle‐in‐cell simulation is performed to study secondary reconnection between two interlinked flux tubes produced by neighboring guide field reconnection x‐lines. The reconnecting magnetic fields of this secondary reconnection is enhanced toward the diffusion region, agree well with that in observations. The magnetic field pileup is attributed to the upstream magnetic tension force, that smashes the flux tubes into each other. We propose that the primary reconnection x‐line length is a key parameter to determine the formation of interlinked flux tubes and secondary reconnection therein. Interlinked flux tubes will form only if the x‐line is short; when the x‐line is long enough, the regular flux ropes are formed instead. The critical x‐line length to form interlinked flux tubes is determined by the distance between two neighbor x‐lines and the magnetic shear angle of the primary reconnection. The results provide a novel scenario of secondary reconnection generation during three‐dimensional reconnection.

Behavior of sodium dodecyl sulfate at the gas–liquid interface based on the coupling of temperature and calcium chloride concentration

Coal spontaneous combustion disasters frequently occur during deep coal mining, resulting in significant losses. Water-based foam has been shown to effectively inhibit coal spontaneous combustion disasters. The temperature of coal seam depths is a key factor influencing the stability and water retention capacity of foam. Inorganic salts, as a foam additive, have a notable impact on the structure of the bubble film. Here, the influence of temperature and calcium chloride concentration on the gas–liquid interface of sodium dodecyl sulfate (SDS) was further investigated using molecular dynamic simulations. The results indicate that calcium chloride strengthens the interfacial adsorption barrier and decreases the diffusion coefficient of water, which improves foam stability. Meanwhile, Ca2+ is concentrated in the outer Helmholtz plane of the Stern layer, while Na+ is concentrated in the inner Helmholtz plane. The preferential coordination of Ca2+ further induces the expulsion of Na+. The hydration environment of Na+ is weakened by the electrostatic shielding effect of the Ca2+ layer. Furthermore, temperature and CaCl2 concentration exhibit a synergistic effect, influencing the adsorption structure of SDS at the interface. Temperature and CaCl2 cause the SDS head group to orient more perpendicularly to the interface. Therefore, the two-dimensional distribution of SDS in the XY plane exhibits regions of aggregation, diffusion, and vacant sites. With changes in temperature and Ca2+ concentration, the proportion and number density of vacant sites gradually stabilize. SDS forms highly ordered aggregates at the air–liquid interface, which in turn enhances the stability of the foam film.

Capsule Electron Distributions Near the Diffusion Region of Magnetic Reconnection

AbstractUnderstanding electron kinetic processes is crucial for elucidating the energy conversion mechanisms in magnetic reconnection. Non‐Maxwellian electron distributions are strong indicators of kinetic‐scale processes near the electron diffusion region, yet they remain incompletely understood. Using in‐situ spacecraft data from 29 magnetopause reconnection events, we unambiguously identify a non‐Maxwellian capsule electron distribution near the electron diffusion region. This distribution comprises an elongated component parallel with the magnetic field at lower energies and a butterfly component (with peaks at pitch angles near and ) at higher energies. We provide evidence that these distributions are partly linked to electron trapping and preferential heating along the direction of magnetic fields. The parallel electric potentials needed for the parallel heating may be linked to kinetic Alfvén waves. These capsule‐like electron distributions are also found to generate whistler emissions. Our results suggest that these kinetic processes are prevalent in magnetic reconnection.

A consistent diffuse-interface model for two-phase flow problems with rapid evaporation

We present accurate and mathematically consistent formulations of a diffuse-interface model for two-phase flow problems involving rapid evaporation. The model addresses challenges including discontinuities in the density field by several orders of magnitude, leading to high velocity and pressure jumps across the liquid–vapor interface, along with dynamically changing interface topologies. To this end, we integrate an incompressible Navier–Stokes solver combined with a conservative level-set formulation and a regularized, i.e., diffuse, representation of discontinuities into a matrix-free adaptive finite element framework. The achievements are three-fold: First, we propose mathematically consistent definitions for the level-set transport velocity in the diffuse interface region by extrapolating the velocity from the liquid or gas phase. They exhibit superior prediction accuracy for the evaporated mass and the resulting interface dynamics compared to a local velocity evaluation, especially for strongly curved interfaces.Second, we show that accurate prediction of the evaporation-induced pressure jump requires a consistent, namely a reciprocal, density interpolation across the interface, which satisfies local mass conservation. Third, the combination of diffuse interface models for evaporation with standard Stokes-type constitutive relations for viscous flows leads to significant pressure artifacts in the diffuse interface region. To mitigate these, we propose to introduce a correction term for such constitutive model types. Through selected analytical and numerical examples, the aforementioned properties are validated. The presented model promises new insights in simulation-based prediction of melt–vapor interactions in thermal multiphase flows such as in laser-based powder bed fusion of metals.

NIMG-44. ELEVATED TRANSLOCATOR PROTEIN 18KDA BINDING IN LOW MEAN DIFFUSIVITY CLUSTERS IS A FEATURE OF THE TRANSFORMING GLIOMA AND IDH MUTANT GLIOMA MICROENVIRONMENT

Abstract Around 95% of low-grade gliomas undergo anaplastic de-differentiation into high-grade gliomas, a process only partially understood from in vivo clinical imaging. 11 patients with suspected transforming gliomas underwent a combined magnetic resonance imaging (MRI) and positron emission tomography (PET) protocol, incorporating post-contrast T1-weighted/FLAIR acquisition for tumour delineation and diffusion tensor imaging. The PET radiotracer [11C]-(R)-PK11195 assessed translocator protein 18kDa (TSPO) distribution, whose upregulation is associated with inflammation/glioma progression. [11C]-(R)-PK11195 binding potential (BPND) maps were generated using the simplified reference tissue model, with the grey-matter cerebellar time-activity curve serving as the reference tissue input function. KMeans clustering of mean diffusivity (MD) intensity values defined spatially distinct “habitats” of high/low MD voxels within the glioma microenvironment. BPND values within high/low MD clustering habitats were evaluated, across glioma grades and isocitrate dehydrogenase (IDH) mutational status. Across all grade 2 and 3 gliomas (n= 6), mean TSPO BPND values in low MD habitats (0.0383 ±0.102) were significantly greater than high MD habitats (-0.045 ±0.142) (p= 0.003). In grade 4 gliomas (n= 5), no significant difference was observed in mean BPND values between low (0.514 ±0.176) and high (0.465 ±0.296) MD habitats (p= 0.543). IDH mutant gliomas (n= 7) exhibited significantly higher mean BPND in low MD habitats (0.116 ±0.225), relative to high habitats (0.052 ±0.287) (p= 0.021). IDH wildtype gliomas (n= 4) showed no significant differences between BPND values in low (0.498 ±0.199) and high MD habitats (0.424 ±0.325) (p= 0.467). Our novel findings demonstrate spatial heterogeneity in TSPO expression within 2/3/IDH mutant gliomas, a characteristic absent from grade 4/IDH wildtype varieties. Regions of restricted diffusion with high TSPO signal in grade 2/3/IDH mutant tumours indicate the heterogenous distribution of active TSPO-expressing immune/neoplastic cell populations, contrasting the homogenous distribution in grade 4/IDH wildtype gliomas, highlighting differences between their inflammatory profile and pathological features.

Theoretical study of the solution of the diffusion equation under effect of the magnetic field on the silicon solar cell

PurposeThe purpose of this study is to investigate the behavior of a silicon solar cell when subjected to a magnetic field. Specifically, the study aims to understand how the presence of the magnetic field influences the distribution of excess minority carriers within the base region of the solar cell. By solving the one-dimensional continuity equation under these conditions, the study seeks to elucidate the transient dynamics of carrier generation, recombination and transport processes. This research contributes to the broader understanding of how external magnetic fields can impact the performance and efficiency of silicon solar cells, potentially informing future optimizations or applications in photovoltaic technology.Design/methodology/approachThe solar cell is assumed to be uniformly illuminated, which simplifies the analysis of carrier generation to a function of depth (x). The emitter and space charge region contributions are considered while neglecting the diffusion region. The injection level remains constant throughout the analysis, focusing specifically on the base thickness region, H = 200 µm.FindingsThe findings of this study reveal significant insights into the behavior of a silicon solar cell under the influence of a magnetic field. Key findings include Impact on carrier distribution: the magnetic field affects the distribution of excess minority carriers within the base region of the solar cell. This distribution is crucial for understanding the efficiency of carrier collection and overall cell performance. Transient dynamics: the transient behavior of carrier generation, recombination and transport processes in the base region is influenced by the magnetic field. This understanding helps in predicting the response time and effectiveness of the solar cell under varying magnetic field strengths. Optimization potential: insights gained from this study suggest potential strategies for optimizing the design and operation of silicon solar cells to enhance their performance in environments where magnetic fields are present. Theoretical framework: the study provides a theoretical framework based on the one-dimensional continuity equation, offering a systematic approach to analyzing and predicting the behavior of solar cells under magnetic field conditions. These findings contribute to advancing the understanding of how external factors such as magnetic fields can impact the operation and efficiency of silicon solar cells, thereby guiding future research and development efforts in photovoltaic technology.Originality/valueThe originality and value of this study lie in its contribution to advancing the understanding of how magnetic fields influence silicon solar cell performance, providing both theoretical insights and potential practical applications in diverse technological contexts.

A Bifurcated Reconnecting Current Sheet in the Turbulent Magnetosheath

We report the Magnetospheric Multiscale (MMS) observation of a bifurcated reconnecting current sheet in Earth’s dayside magnetosheath. Typical signatures of the ion diffusion region, including sub-Alfvénic demagnetized ion outflow, super-Alfvénic electron flows, Hall magnetic fields, electron heating, and energy dissipation, were found when MMS traversed the current sheet. The weak ion exhaust at the current sheet center was bounded by two current peaks in which super-Alfvénic electron flow directed toward and away from the X line were observed, respectively. Both off-center current peaks were primarily carried by electrons, one of which was supported by field-aligned current, while the other was mainly supported by current driven by electric field drift. The two current peaks also exhibit other differences, including electron heating, electron pitch angle distributions, electron nongyrotropy, energy dissipation, and magnetic field curvature. An ion-scale magnetic flux rope was detected between the two current peaks where electrons showed field-aligned bidirectional distribution, in contrast to field-aligned distribution parallel to the magnetic field in two current peaks. The observed current sheet was embedded in a background shear flow. This shear flow worked together with the guide field and asymmetric field and density to affect the electron dynamics. Our results reveal the reconnection properties in this special plasma and field regime which may be common in turbulent environments.

Superconductivity at Pd/Bi2Se3 Interfaces Due to Self-Formed PdBiSe Interlayers.

Understanding the physical and chemical processes at the interfaces of metals and topological insulators is crucial for the development of the next generation of topological quantum devices. Here, we report the discovery of robust superconductivity in Pd/Bi2Se3 bilayers fabricated by sputtering Pd on the surface of Bi2Se3. Through transmission electron microscopy measurements, we identify that the observed interfacial superconductivity originates from the diffusion of Pd into Bi2Se3. In the diffusion region, Pd chemically reacts with Bi2Se3 and forms a layer of PdBiSe, a known superconductor with a bulk transition temperature of 1.5 K. Our work provides a method for the introduction of superconductivity into Bi2Se3, laying the foundation for the development of sophisticated Bi2Se3-based topological devices.

Probing Three-dimensional Magnetic Fields. III. Synchrotron Emission and Machine Learning

Synchrotron observation serves as a tool for studying magnetic fields in the interstellar medium and intracluster medium, yet its ability to unveil three-dimensional (3D) magnetic fields, meaning probing the field’s plane-of-the-sky (POS) orientation, inclination angle relative to the line of sight, and magnetization from one observational data, remains largely underexplored. Inspired by the latest insights into anisotropic magnetohydrodynamic (MHD) turbulence, we found that synchrotron emission’s intensity structures inherently reflect this anisotropy, providing crucial information to aid in 3D magnetic field studies: (i) the structure’s elongation gives the magnetic field’s POS orientation and (ii) the structure’s anisotropy degree and topology reveal the inclination angle and magnetization. Capitalizing on this foundation, we integrate a machine learning approach—convolutional neural network (CNN)—to extract this latent information, thereby facilitating the exploration of 3D magnetic fields. The model is trained on synthetic synchrotron emission maps, derived from 3D MHD turbulence simulations encompassing a range of sub-Alfvénic to super-Alfvénic conditions. We show that the CNN is physically interpretable and the CNN is capable of obtaining the POS orientation, inclination angle, and magnetization. Additionally, we test the CNN against the noise effect and the missing low-spatial frequency. We show that this CNN-based approach maintains a high degree of robustness even when only high-spatial frequencies are maintained. This renders the method particularly suitable for application to interferometric data lacking single-dish measurements. We applied this trained CNN to the synchrotron observations of a diffuse region. The CNN-predicted POS magnetic field orientation shows a statistical agreement with that derived from synchrotron polarization.

Current Sheet Broadening due to Turbulence in Three-dimensional Collisionless Reconnection

The present study has investigated the statistical distribution of the current sheet width across the reconnection diffusion region by means of the 3D particle-in-cell simulations. The 3D reconnection layers are unstable to the flow shear instabilities, which results in electromagnetic (EM) turbulence generating effective magnetic dissipation around the x-line. The simulations are performed for several ion-to-electron mass ratios and computational domain sizes, which determine the fastest-growing mode in each simulation run. When the turbulence is weak, the current sheet width increases with the turbulence intensity, following a theoretical curve independent of the mass ratio and domain size. However, when the turbulence is stronger, the width saturates at a low level around 2 times the local electron inertia length, i.e., much smaller than the ion kinetic scales. It is found that the intense inductive electric field due to the EM turbulence is partly canceled out by the eddy viscous effect. As a result, the reconnection electric field is almost unchanged during the quasi-steady phase, regardless of the turbulence intensity. The result implies that the magnetohydrodynamic turbulence models are unlikely to be applicable to the reconnection diffusion region.

Hypoechoic ultrasonographic findings in the patellar ligaments are common in riding and trotting horses in training (116 cases).

Patellar ligament (PL) injuries are increasingly being reported in horses, but few studies have described the normal PL ultrasonographic appearance in horses. The aims of this prospective observational study were to describe the ultrasonographic appearance of the PLs and infrapatellar fat pad in a population of horses in training and to relate the ultrasonographic findings to objectively measured movement asymmetry. B-mode and color Doppler ultrasonographic examination of the PLs and infrapatellar fat pad in both hind limbs and objective gait analyses were performed on the 116 riding and trotting horses included in the study. The association between ultrasonographic findings, horse age, and movement asymmetry during the trot was then investigated. Distinct or diffuse hypoechoic regions were commonly found in the intermediate PL (24/116; 20.7%), especially in the caudal aspect of the mid-third of the ligament. The infrapatellar fat pad had a hypoechoic striated appearance in all horses except one, in which it was hyperechoic. No association was found between ultrasonographic findings in the PLs and infrapatellar fat pad and lameness. It is important to recognize that there is biological variation in PL appearance, which may or may not be associated with pain in this area, therefore emphasizing the use of local analgesia to determine the location of the lameness.

Impact of the Out‐Of‐Plane Flow Shear on Magnetic Reconnection at the Flanks of Earth's Magnetopause

AbstractMagnetic reconnection changes the magnetic field topology and facilitates the energy and particle exchange at magnetospheric boundaries such as the Earth's magnetopause. The flow shear perpendicular to the reconnecting plane prevails at the flank magnetopause under southward interplanetary magnetic field conditions. However, the effect of the out‐of‐plane flow shear on asymmetric reconnection is an open question. In this study, we utilize kinetic simulations to investigate the impact of the out‐of‐plane flow shear on asymmetric reconnection. By systematically varying the flow shear strength, we analyze the flow shear effects on the reconnection rate, the diffusion region structure, and the energy conversion rate. We find that the reconnection rate increases with the upstream out‐of‐plane flow shear, and for the same upstream conditions, it is higher at the dusk side than at the dawn side. The diffusion region is squeezed in the outflow direction due to magnetic pressure which is proportional to the square of the Alfvén Mach number of the shear flow. The out‐of‐plane flow shear increases the energy conversion rate , and for the same upstream conditions, the magnitude of is larger at the dusk side than at the dawn side. This study reveals that out‐of‐plane flow shear not only enhances the reconnection rate but also significantly boosts energy conversion, with more pronounced effects on the dusk‐side flank than on the dawn‐side flank. These insights pave the way for better understanding the solar wind‐magnetosphere interactions.

Statistical Study of Energy Transport and Conversion in Electron Diffusion Regions at Earth's Dayside Magnetopause

AbstractThe electron diffusion region (EDR) is a key region for magnetic reconnection, but the typical energy transport and conversion in EDRs is still not well understood. In this work, we perform a statistical study of 80 previously published near X‐line events identified at the dayside magnetopause in Magnetospheric Multiscale data. We find 44 events that clearly present all commonly accepted EDR signatures and use this database to investigate energy flux partition and energy conversion. We find that energy partition is changed inside EDRs, with a 71%–29% allocation of particle energy flux density between electrons and ions respectively. The electron enthalpy flux density is found to dominate locally at all EDRs and is predominantly oriented in the out‐of‐plane direction, perpendicular to the reconnecting magnetic field. We also examine the transition from electron‐ to ion‐dominated energy flux partition further from the EDR, finding this typically occurs at scales of the order of the ion inertial length, larger than the typical EDR size. We then investigate energy conversion and transport and highlight complex processes, with potential non‐steady‐state energy accumulation and release near the EDR. We discuss the implications of our results for reconnection energy conversion, and for magnetopause dynamics in general.

Study of the Ion-Exchange Capacity of Clinoptilolite for Copper Ions under Ideal Displacement Conditions in the Dynamic Mode

The ionic mechanism of copper ion sorption from an aqueous medium has been confirmed. The study has elucidated the regularities of the process within a stirred bed reactor, where kinetics are limited by the internal diffusion region. Initial sorption curves under dynamic conditions have been obtained.

Dynamic behaviors of interfacial oxides and elements during the ultrasonic-assisted diffusion bonding of 6063Al alloys

Efficiently breaking the oxide layer and rapidly diffusing of elements at low-temperature has been a longstanding goal in the diffusion bonding (DB) of Al alloys. To break the interfacial oxide layers and accelerate atomic diffusion, ultrasound energy was introduced during the DB of 6063Al. A full Zn–Al eutectoid joint was manufactured via a pure Zn interlayer at 360 °C in atmospheric by an ultrasonic-assisted diffusion bonding (U-DB) at only an ultrasonic vibration of10 min. During U-DB, brittle cracks were formed in the interfacial oxide layers due to high strain rate induced by ultrasonic action. Zn diffused into Al alloy through the brittle cracks in oxide layers via “subcutaneous diffusion,” forming a Zn–Al eutectoid diffusion region between the Al alloy and oxide layer. The oxide fragments irregularly migrated to the center of the joint due to Kirkendall effect and ultrasonic action, finally dispersed in the bonded metal. The bonded metal finally transformed as a full Zn–Al eutectoid phase after consuming interlayer. The shear strength of the Zn–Al eutectoid joint reached 82.6 MPa. The Zn–Al mutual diffusion coefficient of U-DB at 360 °C was ∼0.6 μm2/s, which was about 20 times higher than the thermal diffusion coefficient under same temperature condition. Additionally, the mechanism of ultrasonic-assisted diffusion based on the strain-driven diffusion mode was discussed in detail.

Characterization of irradiation-induced dislocation loops in Vanadium at 25-500 °C

Vanadium-based alloys have emerged as promising candidates for structural materials in fusion applications. However, as its base metal, the response of V to irradiation has received limited attention in prior studies. To gain a fundamental understanding of the irradiation damage in V, its microstructure evolution under 6 MeV Ti ion irradiation at 25–500 °C is investigated in the present study, with the focus on the detailed and comprehensive characterization of the behavior of the irradiation-introduced dislocation loops. Under room temperature irradiation, the “black dot” dislocation loops agglomerate linearly into rafts, during which their Burgers vectors are well aligned. With the temperature increases to 300 °C, the size of rafts increases and the density decreases, while the size of small loops maintains similar to the room temperature irradiation condition. As the irradiation temperature reaches 500 °C, the defects become highly mobile, resulting in the formation of extended dislocation loops or lines with hundreds of nanometers in size, with the rafts vanishing. All the observable loops under this irradiation temperature range exhibit the Burgers vectors of a/2 < 111>. All the loops observed in the displacement region are identified to be interstitial-type, while a small portion of loops observed in the diffusion region under elevated temperatures are vacancy-type.