Early Stage Of Discharge Research Articles

Diagnosis of Li-ion battery degradation based on resistive and diffusion-related transient voltage changes at early stage of discharge

Lithium-ion batteries degradation can be classified into capacity reduction and increase of the internal resistance. Accurate estimation of the degradation is important to determine the economic value and the remaining useful life of the battery. This paper proposes a method which analyzes the transient voltage response at the early stage of discharge, starting from the fully charged state. An equivalent circuit composed by a series resistance and a Warburg element is adopted to fit the transient voltage. The Warburg element is modeled as a transmission line composed by a ladder of resistances and capacitances. The method is validated with data obtained before and after aging cycles performed at 1.4 C charge and 2.0 C discharge rates, at 25 °C, 10 °C and −5 °C. The loss of cyclable lithium is deemed to be the main reason behind the battery degradation at all the tested temperatures. The dependency of the Warburg parameter to the remaining cell capacity is the same regardless of the aging temperature, suggesting that estimation of the Warburg parameter provides information about the state of health of the cell. On the other hand, the relationship between the capacity reduction and the increase of resistance has a temperature-dependent slope with low increase at lower temperatures where lithium plating is likely to occur. Accordingly, a relatively low resistance increase is deemed to be the sign of lithium plating.

Nanosecond photography observation of the discharge process across the 220 kV/500 kV insulators in lightning impulse

Long air gap discharge is the basis for the study of lightning protection and external insulation design of high voltage lines. However, there is a lack of detailed and comprehensive observation of the long air gap discharge process at the ns-level, as well as higher voltage insulator discharge observations. In this paper, the lightning impulse discharge/flashover tests are conducted on 220 kV glass insulators and 500 kV glass/composite insulators. Firstly, the U50% test is performed to determine the U50% value of each insulator under standard lightning impulse, and 1.1U50%, slightly higher than U50%, is applied to ensure the breakdown of the insulator. Subsequently, emICCD is utilized with a very short exposure time (minimum 10 ns) to obtain repeated single shots of discharge images under different delays, exposure times and light intensity gain. These images were spliced together based on time sequence to create a continuous discharge process. The discharge processes of 220 kV glass insulator and 500 kV glass/composite insulator are compared and analyzed. The results show that in the early stage of discharge, the discharge processes at the low voltage end of both 220 kV and 500 kV glass insulators are more intense. Additionally, the downward leader is faster than the upward leader in the discharge process of 500 kV composite insulators.

The Safety and Effectiveness of Telemedicine for Cancer-Related Colostomy Care in the Early Stage of Discharge: A Prospective, Randomized, Single-Center Study.

There has been an exponential growth in the use of telemedicine services to provide clinical care. However, the safety and effectiveness of telemedicine in cancer-related colostomy care during the early stages of discharge remain unclear. This study aimed to support that the safety and effectiveness of telemedicine in cancer-related colostomy care were not inferior to those of outpatient care. This was a prospective randomized noninferiority study. A total of 76 consecutive patients who underwent cancer-related colostomy stoma were enrolled and randomly divided into a telemedicine group or an outpatient group with an equal allocation ratio (1:1). The outpatient group was provided in-person interview mode colostomy care, whereas the telemedicine group was provided video interview mode colostomy care. The stoma-related complications, self-care ability, and quality of life reflected the safety and effectiveness of colostomy care in the early stages of discharge. The incidence of stoma-related complications within two weeks and one month after discharge was not significantly different between the two groups (p 2-weeks = 0.772 and p 1-month = 0.760). The mean NCI-CTCAE score for stoma-related complications was less than level 2. The ESCA and C-COH-QOL-OQ scores were not significantly different between the telemedicine and outpatient groups at two weeks and one month after discharge (all p > 0.05). The results revealed that the safety and effectiveness of telemedicine for cancer-related colostomies in the early stages of discharge were not inferior to those of outpatient care alone.

Tuning Discharge Behavior of Hollandite α-MnO2 in Hydrated Zinc Ion Battery by Transition Metal Substitution

The tunnel-type hollandite α-MnO2 is a promising cathode material for rechargeable aqueous zinc-ion batteries (ZIBs) due to its low cost in synthesis and high energy density. However, irreversible structural degradation upon continuous cycling prevents the cathode from being utilized commercially. Herein, density functional theory (DFT) was utilized to conduct a systematic study on tuning the behavior of α-MnO2 by substituting the Mn ions on the tunnel wall with a transition metal (V or Cr) during the H+-/Zn2+-intercalation in hydrated ZIB. Our study revealed that both substituents aid cyclability and capacity retention with Cr outperforming V. In term of discharge voltage, only the Cr-substitution displays clear promotion at the early stage of discharge. The superior performance of substituted Cr4+ comes from its unique atomic and electronic structures. Upon discharge, it can be reduced to Cr3+ more readily than Mn4+ and thereby limits the formation of unstable Mn3+ or Mn2+ centers; the formed Cr3+ is more stable than Mn3+ and Mn2+ from the reduction of Mn4+; and Cr3+ can also greatly stabilize the neighboring Mn ions. This study highlights the significant tuning effect of transition metal substitution on the electrochemical and physical performance of α-MnO2 as a cathode in hydrated ZIBs.

Early Mental Health and Quality of Life in Discharged Patients With COVID-19.

Aim: This study aimed to analyze the early mental health (MH) and quality of life (QoL) of discharged patients with coronavirus disease 2019 (COVID-19), which can provide a scientific basis for the further development of intervention programs.Methods: In total, 108 subjects participated in this study, including an experimental group (90 patients diagnosed with COVID-19 from March to April 2020 and hospitalized in Wuhan China Resources & WISCO General Hospital, Wuhan, China, 83.3%) and a control group (18 healthy participants, 16.7%). Their MH and QoL were measured through the 12-item Short Form Health Survey version 2 (SF-12v2), the Self-rating anxiety scale (SAS), the Self-rating depression scale (SDS), and the International Physical Activity Questionnaire (IPAQ). The results of questionnaires were compared between these two groups.Results: (1) Comparison of anxiety status: among 90 discharged patients with COVID-19, 30 patients (33.3%) had a state of anxiety. Compared with healthy participants and the general population, patients with COVID-19 in the early stages of discharge had a higher incidence of anxiety and more severe anxiety symptoms (P < 0.05). (2) Comparison of depression status: among 90 discharged patients with COVID-19, 29 patients (32.2%) had a state of depression. Compared with healthy participants and the general population, patients with COVID-19 in the early stages of discharge had a higher incidence of depression and more severe depression symptoms (P < 0.05). (3) Comparison of QoL: 78 patients (86.7%) presented a decrease in physical health-related quality of life (HRQoL) and 73 patients (81.1%) presented a decrease in psychology-related QoL. The SF-12v2 physical component summary (PCS) and the SF-12v2 mental component summary (MCS) of patients were significantly lower than those of healthy people, especially in physical function (PF), vitality (VT), social function (SF), and mental health (MH) (all P < 0.05). (4) Gender differences in mental health and the QoL among patients with COVID-19: women had more severe anxiety/depression symptoms than men (P < 0.05). The scores of women in all dimensions of SF-12V2 were lower than those of men, and there were statistically significant differences between the two groups in PCS, PF, general health (GH), VT, and role-emotional (RE) (P < 0.05).Conclusion: During the early phase after being discharged, patients with COVID-19 might experience negative emotions, such as anxiety or depression, and also problems with reduced QoL, especially among female patients. Therefore, an intervention plan should focus on strengthening psychological condition and improving physical function, and gender-specific rehabilitation programmes should be adapted to improve psychological status and QoL.

A Defect Spinel Cathode Material for Long-Life and High-Energy-Density Magnesium Rechargeable Batteries

Magnesium rechargeable batteries (MRBs) have been a promising candidate for next-generation batteries due to the following reasons: (i) Mg can deposit without dendritic formation, enabling us to safely use Mg metal itself as a high-capacity (2205 mAh/g) anode. (ii) The electrode potential of Mg (-2.4 V vs. SHE) is relatively low among metal anodes for multivalent batteries, which is attractive for achieving high cell voltage. (iii) Mg is an abundant and non-toxic element. The development of MRBs, however, has been hindered by the lack of high-performance cathode materials. The difficulty in the development of cathode materials is derived from the high charge density of divalent Mg2+ ion, which is almost twice that of monovalent Li+ ion since their ionic radii are similar. This leads to the high activation energies for Mg2+ diffusion in cathode materials by the strong electrostatic interaction with anions. High-temperature operation is a way to prevent the problem of the sluggish Mg2+ diffusion; thus, we have been developing high-potential spinel oxide cathode materials that can work at 150℃. We have found several promising cathode materials (e.g., MgCo2O4, ZnCo2O4) [1,2], but they show rapid capacity fading during battery cycling. Such stoichiometric spinel oxides coherently transform to the rocksalt structure accompanied by Mg insertion in the two-phase reaction [1]. Therefore, the cycle degradation can be attributed to the formation of the rocksalt phase on the surface of active material particles, which would impede the diffusion of Mg2+ ions and degrade the reversibility of structural change in discharge/charge.Very recently, we have proposed a strategy of utilizing defect spinel oxides, which contain cation deficiencies at the octahedral sites in the spinel structure, to suppress the structure transition into the densely packed rocksalt phase in the early stage of discharge (i.e., Mg insertion) [3]. We have chosen ZnMnO3 as a promising candidate for defect spinel-type cathode material in that Zn stabilizes the spinel structure [2] and Mn allows the valence change from tetravalent to divalent [1]. By the theoretical and experimental approach, we have confirmed that ZnMnO3 with cation deficiencies at the octahedral sites is stable, and Mg2+ ions are preferentially inserted into the cation-deficient sites at the potential of 2–3 V vs. Mg2+/Mg with keeping spinel-based structures. As a consequence, it has been demonstrated that ZnMnO3 cathode exhibits a long-term cyclability exceeding 100 cycles (see Figure 1), which is in strong contrast to the previous stoichiometric spinel oxides. In this presentation, we will show a general guideline for designing spinel cathode materials suitable for MRBs, and discuss the origin of the high performances of defect spinel ZnMnO3 in terms of element selection, structure modification, and phase-change behavior.

Investigation of Magnesium–Sulfur Batteries using Electrochemical Impedance Spectroscopy

The present study aims to fundamentally understand the magnesium-sulfur battery and the interfacial processes involved. Therefore, electrochemical impedance spectroscopy (EIS) was carried out on symmetrical Mg/Mg and S/S cells as well as on full Mg/S cells. Besides the electrochemical behavior at the open-circuit voltage (OCV), the impedance evolution during the first discharge has been investigated at equidistant states of charge (SOC) and different temperatures. It was confirmed that sulfur species diffuse into the electrolyte, causing initial self-discharge and contributing to the solid electrolyte interphase (SEI) formation, even during the early stages of discharge. In fact, elevated temperatures further boost the self-discharge, but on the other hand significantly enhance the magnesium sulfide formation. Besides sulfur species, magnesium fluoride was found to be a main SEI component on both, anode and cathode side. According to these findings, equivalent circuit models (ECM) are proposed, indicating the formation of a high resistance passivation layer on the magnesium electrode as well as a rather slow cathodic charge transfer and sluggish MgS nucleation kinetics at the sulfur electrode.

Wczesne przewidywanie czasu pozostałego do rozładowania baterii litowo-jonowej z uwzględnieniem korelacji parametrów z różnych etapów procesu rozładowania

In this paper, we propose a method for making early predictions of remaining discharge time (RDT) that considers information about future battery discharge process. Instead of analyzing the entire degradation process of a battery, as in the existing literature, we obtain the information about future battery condition by decomposing the discharge model into three stages, according to level of voltage loss. Correlation between model parameters at the first and last stages of discharge process allows the values of model parameters in the future to be used to predict the value of parameters at early stages of discharge. The particle swarm optimization (PSO) and particle filter (PF) algorithms are employed to update parameters when new voltage data is available. A case study demonstrates that the proposed approach predicts RDT more accurately than the benchmark PF-based prediction method, regardless of the degradation period of the battery.

Mechanism Investigation of High-Performance Li–Polysulfide Batteries Enabled by Tungsten Disulfide Nanopetals

Understanding the reaction kinetics and mechanism of Li-polysulfide batteries is critical in designing advanced host materials for improved performance. However, up to now, the reaction mechanism within the Li-polysulfide batteries is still unclear. Herein, we study the reaction mechanism of a high-performance Li-polysulfide battery by in situ X-ray diffraction (XRD) and density functional theory (DFT) calculations based on a multifunctional host material composed of WS2 nanopetals embedded in rGO-CNT (WS2-rGO-CNT) aerogel. The WS2 nanopetal serves as a "catalytic center" to chemically bond the polysulfides and accelerate the polysulfide redox reactions, and the 3D porous rGO-CNT scaffold provides fast and efficient e-/Li+ transportation. Thus, the resulting WS2-rGO-CNT aerogel accommodating the polysulfide catholyte enables a stable cycling performance, excellent rate capability (614 mAh g-1 at 2 C), and a high areal capacity (6.6 mAh cm-2 at 0.5 C). In situ XRD results reveal that the Li2S starts to form at an early stage of discharge (at a depth of 25% of the lower voltage plateau) during the discharge process, and β-S8 nucleation begins before the upper voltage plateau during the recharge process, which are different from the conventional Li-S battery. Moreover, the WS2 itself could be lithiated/delithiated during the cycling, making the lithiated WS2 (Li xWS2, 0 ≤ x ≤ 0.3) a real host material for Li-polysulfide batteries. DFT calculations suggest that Li xWS2 (0 ≤ x ≤ 0.3) exhibits moderate binding/anchoring interactions toward polysulfides with adsorption energies of 0.51-1.4 eV. Our work reveals the reaction mechanism of the Li-polysulfide batteries and indicates that the lithiated host plays an important role in trapping the polysulfides.

One-year Unplanned Readmission After Colorectal Cancer Surgery in Western China

ABSTRACTPurpose: Readmissions are common after colorectal cancer surgery. There are limited data related one-year unplanned readmission after colorectal cancer surgery. The aim of this study was to ascertain the incidence rate of unplanned readmission in Western China, identify causes and risk factors of one-year unplanned readmission (UR) in patients who underwent enhanced recovery pathways for colorectal cancer (CRC) surgery. Materials and Methods: A retrospective study using a CRC surgery database of patients treated in West China Hospital was performed. Patients who underwent enhanced recovery pathways for colorectal cancer surgery between January 2013 and May 2016 were investigated. The postoperative follow-up data were all routinely recorded for up to one year or more, the one-year unplanned readmission rate after initial discharge and major reasons for UR were recorded. Multivariate logistic regression analyses was used to identify risk factors of UR. Results: A total of 446 patients were included, with 18.6% of patients readmitted. In a multivariable analysis, preoperative comorbidity was associated with the largest risk of readmission (odds ratio, 2.91[95% CI, 1.32– 6.99]). The main reason of readmission within 30 days after discharge was wound bleeding or infection. While intestinal obstruction was the major cause for readmission after 3 months of discharge.Conclusions: One-year unplanned readmission occurs frequently after CRC in Western China and is strongly associated with preoperative comorbidity. Attention should be paid to wound healing at the early stage of discharge, and bowel obstruction 3 months after discharge.

Improved electrochemical performance of ordered mesoporous carbon by incorporating macropores for Li‒O2 battery cathode

Optimized porous structure is a prerequisite for high performance Li‒O2 battery cathode. Macroporous-mesoporous carbon (MMC) is fabricated via a nano-replication method using mesoporous SiO2 (KIT-6) containing NiO as the template. By varying the amount of NiO in the KIT-6/NiO composite template, the amount of macropores inside MMC is easily controlled. The as-prepared MMC exhibits a highly porous structure with abundant ordered mesopores along with macropores that are larger than 200 nm in size. When the MMC is applied as the cathode material in a Li‒O2 battery, the cell exhibits greatly improved electrochemical performance in comparison to a cell using conventional ordered mesoporous carbon (OMC) without macropores. Systematic studies indicate that while mesopores in the OMC are clogged with Li2O2 formed during the early stage of discharge, the MMC sufficiently accommodates a large amount of Li2O2 in the pores. In addition, Li2O2 with poor crystallinity forms on the cathode containing MMC during subsequent discharge processes, which can be due to the accumulated side product and the limited size of pores. The formation of amorphous Li2O2 and the expedited mass transport through the interconnected meso- and macropores of MMC can attribute to the improved electrochemical performance of the MMC cathode material.

Carbon nanofiber@platinum by a coaxial electrospinning and their improved electrochemical performance as a Li−O2 battery cathode

Non-woven mats constructed from carbon nanofibers with metal (Pt, Co, or Pd) nanoparticles on their surfaces (CNF@metal) were fabricated by coaxial electrospinning for use in non-aqueous lithium‒oxygen (Li‒O2) battery (LOB) cathodes. Through coaxial electrospinning, the metal nanoparticles were evenly distributed on the CNF surfaces, and the samples were directly applied as LOB cathodes. Although the Co and Pd nanoparticles did not promote the desired Li‒O2 reactions, the CNF@Pt exhibited much improved electrochemical performance with highly reversible Li‒O2 operations. Therefore, the Li‒O2 cell using the CNF@Pt cathode exhibited significantly enhanced specific capacity, rate capability, energy efficiency, and cycle stability compared to the other samples. The observed formation of Li2O2 film, rather than toroidal particles, on the CNF@Pt after an early stage of discharge may be attributed to greatly reduced overpotentials both on discharge and charge, as well as a considerably prolonged cycle life (163 cycles) with a limiting capacity of 1000 mAh/gc at a current density of 500 mA/gc. In particular, in-situ differential electrochemical mass spectrometry studies revealed that the cycles of the Pt-catalyzed Li‒O2 cell were mainly based on the reversible formation/decomposition of Li2O2, as evidenced by high O2 evolution and negligible CO2 evolution, even after long-term cycles.

Polysulfide Radicals Appearance in Partially Discharged Lithium-Sulfur Battery Analyzed By First-Principles Interpretations of X-Ray Absorption Spectra

The presence and role of polysulfide radicals in the electrochemical processes of lithium sulfur batteries (Li-S) is currently being debated. In particular, the radical trisulfur anion, S3 .-, has concurrently been purported as a key species or has been discounted as existing during battery operation.1,2 While radical species could be formed via a direct electrochemical pathway, the prevailing assumption is formation via the dissociation of Li2S6 to LiS3.3 It is unclear how critical the formation of polysulfide radical anions is to the remaining redox pathways.4 It is not known if the radicals are an essential intermediate for complete reduction of sulfur (or complete oxidation of Li2S). In addition, the concentration of radical anions relative to polysulfide dianion species (Li2Sx) formed during redox reactions has not yet been quantified. Recently, X-ray absorption spectroscopy (XAS) has been utilized to probe Li-S reaction mechanisms.2,4,5 If properly interpreted, sulfur K-edge XAS can provide powerful insights into the molecular species formed during the charge and discharge reactions of the Li-S battery. The challenge of interpreting spectroscopic data of Li-S chemistry has been the lack of spectral standards for isolated polysulfide species. Due to possible spontaneous polysulfide disproportionation and the establishment of equilibrium mixtures in solution, establishing standards for specific molecular species is necessarily complicated, if not impossible. As a result, fingerprinting is frequently performed using solid analogs, which may induce errors in the analysis since the correspondence between the solid and solution phase XAS is by no means guaranteed. A recent advance towards establishing standards, and thus atomistic interpretations of XAS experimental measurements, has been the use of electronic structure methods based on density functional theory (DFT). In a previous work we demonstrated that the XAS of dissolved lithium polysulfide dianion species and various polysulfide radicals can be obtained via first-principles molecular dynamics and DFT spectral simulations.7,8 In this work, XAS was performed on Li-S cells containing an ether-based electrolyte. Cells were discharged to various depths and probed using XAS at the sulfur K-edge. First principles calculations were performed to obtain XAS of single polysulfide molecules. These theoretical spectra were then used to determine the distribution of polysulfide species present in the battery electrolyte.6 This analysis revealed the presence of polysulfide radical anions in significant concentrations after early stages of discharge. Whereas previous studies probed the sulfur cathode in an attempt to directly examine the charge and discharge reaction processes, this present study explores a different question, also pertinent to Li-S cells: if cell discharge were stopped at specific points in the discharge process, what intermediate species would be present in the battery electrolyte after ample time has been given for polysulfide dissolution to occur? This question is of some importance, as real-world consumer batteries will be stopped and started as the user chooses so that it would be useful to know what species can be expected in the battery electrolyte if dissolution were to occur. Our results provide further insight into the discharge and disproportionation reactions that take place in the electrolyte during cycling.

A Sulfur-Impregnated Flow Cathode for High-Energy Lithium Flow Batteries

Introduction Redox flow batteries are promising energy storage technologies but have been suffering from low energy density and low volumetric capacity1, 2. Increasing the energy density of RFBs has been one of the major research efforts for RFBs, which can significantly increases its competitiveness for both stationary and transportation applications3-5. In this work,6we employ sulfur-impregnated carbon (S/C) composite as a flow cathode to achieve high-energy lithium-flow batteries. Pseudo-in situ electrochemical impedance spectroscopy (EIS) are used to reveal superior electrochemical reversibility of the sulfur redox reactions. Our approach of exploiting sulfur-impregnated carbon composite in the flow cathode offers a promising direction to develop high-energy flow batteries. Results and Discussion Figure 1 shows the first discharge/charge profiles and the scanning electron microscope/energy-dispersive X-ray spectroscopy (SEM/EDX) images of a mechanically-mixed sulfur-carbon suspension with 5.0 vol% sulfur-12.0 vol% Ketjen black (5S-12KB-MM, 3.2 M [S]) and a sulfur-impregnated S/C composite suspensions with 5.0 vol% sulfur-12.0 vol% Ketjen black (5S-12KB, 3.2 M [S]). The first gravimetric discharge capacity of the mechanically-mixed 5S-12KB-MM catholyte (700 mAh/gS, 71 Ah/L) is lower than that of the S/C composite 5S-12KB catholyte (1235 mAh/gS, 128 Ah/L) by ~50%. This suggests that the utilization of sulfur in the 5S-12KB catholyte is enhanced by uniformly intermixing of S and C using sulfur impregnation. The SEM/EDX image of the 5S-12KB catholyte shows that the S and C atoms are evenly distributed and overlapped across the composite suspension. On the other hand, the S and C atoms are separated in the mechanically mixed 5S-12KB-MM suspension.6 The influences of the concentration of carbon and the concentration of sulfur on the electrochemical behavior/performance of the S/C catholyte in Li-suspension cells will be discussed. To examine the reversibility of various electrochemical processes of the S/C catholyte, we employed pseudo-in situ EIS measurement as the reaction proceeds. Figure 2 shows the discharge and charge steps of the 20.0 vol% sulpfur-26.0 vol% Ketjen black (20S-26KB, 12.9 M [S]) Li-suspension cells inserted with five EIS measurements (D1 – D5) during discharge and four EIS measurements (C1 – C4) during charging.7, 8. The high-frequency-intercept has been attributed to the cell ohmic resistance, the middle-frequency semi-circle has been attributed to the interfacial resistance/capacitance of the catholyte and the low-frequency semi-circle has been attributed to the charge-transfer-resistance/pseudo capacitance of the catholyte. First, the ohmic resistance of the catholyte is the smallest and is insensitive to the any steps. Second, the interfacial resistance first decreased (D1–D4) and dramatically increased upon full discharge (D5). This suggests that the interfacial resistance decreases by transforming the insulating solid sulfur to soluble polysulfides, which improves the contacts between sulfur species and carbon, but significantly increases due to the formation of insulating film-like Li2S. The interfacial resistance decreased after charging to polysulfide phase (C1-C3) and remained small at the end of the charging. Finally, no significant increase in the charge-transfer resistance was noticed at early stage of discharge (D1-D3) until the later stage of discharge (D4-D5), which is attributed to the formation of insulating Li2S solids, which blocks the charge transfer. Reversibly, the charge-transfer resistance decreases upon charging, which is attributed to the formation of polysulfides from decomposing the insulating Li2S solid.6 Further investigations on the electrochemical reversibility, energy efficiency, cycle life, single cell design, and flow cell performance at various flow rates will be discussed. Acknowledgments The work described was substantially supported by a grant from the Research Grants Council of the Hong Kong Special Administrative Region, China, under Theme-based Research Scheme through Project No. T23-407/13-N, and partially supported by project RNEp1-13 of the Shun Hing Institute of Advanced Engineering, The Chinese University of Hong Kong.

The influence of toroidal Alfvén modes on the confinement of fast particles in the Globus-M spherical tokamak

Neutral beam injection into the Globus-M spherical tokamak at the early stage of discharge leads to the development of instabilities in a frequency range of 50–200 kHz, which have been identified as toroidal Alfven eigenmodes (TAEs) [1]. The influence of these modes on the confinement of fast particles has been studied with the aid of a neutral particle analyzer (NPA) and a neutron detector. The isotope effect was studied using hydrogen and deuterium both in the injected beam and in the target plasma. A correlation analysis of signals from magnetic probes showed that the observed modes in most cases contain a single harmonic with toroidal number n = 1. Upon the injection of deuterium into deuterium plasma, the development of TAEs led to a decrease in the neutron flux by 25%, whereas the fluxes of high-energy recharge atoms decreased by 75%. After the injection of hydrogen, a decrease in the flux measured by NPA did not exceed 25%.

Reversible Li+ Storage in a LiMnTiO4 Spinel and Its Structural Transition Mechanisms

In this work, LiMnTiO4 (a structural analogue of classic spinel LiMn2O4) with a disordered cubic spinel structure (Fd3̅m) has been synthesized by a low-temperature sol–gel route. The as-obtained LiMnTiO4 exhibits excellent cycling stability in a wide voltage range from 1.5 to 4.8 V with high discharge capacities of 290, 250, and 140 mA h g–1 at a C/40, C/19, and 1C rate, respectively. Combined long- and short-range structural characterization techniques are used to reveal the correlation between structure and electrochemical behavior. During cycling, the charge/discharge profiles of LiMnTiO4 evolve from initially two well-separated plateaus into sloping regimes. In the early stage of discharge, LiMnTiO4 undergoes phase transitions from an initial spinel phase to mixtures of predominant rock-salt (Fm3̅m) and tetragonal (I41/amd) structures along with a decrease in crystallite size from 12 nm to 3 to 4 nm. During further cycling, the spinel/rock-salt phase transition was found to be reversible with the cubic framework remaining intact. The presence of the tetragonal phase after the first discharge suggests that the Mn3+ Jahn–Teller distortion is partially involved during lithiation from Li1–yMn3+yTiO4 to Li1+xMn3–xTiO4 and the fraction of such a tetragonal phase remains at about 30–40% during subsequent cycling.

Dynamics of bubble generated by low energy pulsed electric discharge in water

Results of investigations of bubble formation and dynamics for discharge in water are presented. Experiments were carried out in discharge chamber with axisymmetric electrode system “wire to wire”. Interelectrode gap was varied from 1 to 10 mm. Energy in a pulse was <1 J. Velocity of bubble expantion and collapse is about several hundreds meter per second at early stage of discharge. Bubble pulsation period is 0.5 – 1 ms. Increasing of energy released in the discharge gap will increase bubble pulsation period. Little bubble was formed by reducing energy input into discharge. But the main stage of discharge always followed by bubble formation. Specific erosion is measured for different energy in pulse and matched up with bubble collapse.

Simulation of hydrogen retention and re-emission from tungsten exposed to divertor plasmas

In order to study the diffusion, surface recombination and trapping of hydrogen isotopes in tungsten, the processes are incorporated into a Monte Carlo code, EDDY. After estimating the relevant parameters by simulating an existing thermal desorption spectroscopy (TDS) experiment with the code, the deuterium retention characteristics of a tungsten divertor plate are investigated for an ITER plasma configuration. At the inner divertor plate and the early stage of discharge, the number of mobile D atoms reaches a steady-state value due to the balance between implanted and re-emitted atoms. During discharge, most of the implanted D atoms are retained in traps, and after saturating available traps, inward diffusion and subsequent trapping increase the inventory. The saturation distributes deeply into W at the strike point of the plate, where the surface temperature is higher than that at distance away from it. Most of the trapped atoms remain in the bulk even after discharge, whereas mobile atoms are strongly reduced.

Magnetohydrodynamic Simulation of Tungsten Wire in Wire‐Array Z Pinch

AbstractThe magnetohydrodynamic behavior of tungsten wire ablating in wire‐array Z pinch discharge on MAGPIE is simulated in a two‐dimensional fine‐grid domain using the GORGON code. A nonideal resistivity model has been implemented in the simulation to obtain plasma transport coefficients in the high density regime along with a screened hydrogenic model to calculate the radiative cooling. Starting from the initial state of warm dense plasma, the evolution of ablated wire is demonstrated to show its explosion and implosion dynamics as a function of discharge time and then the computed profile of electron density is compared with the contour lines reproduced from the measurement by a laser interferometer during the early stage of discharge. The comparison overall shows a fair agreement in terms of the magnitude and the profile shape while some discrepancies can be attributed to the simplified description of the internal wire core physics (© 2010 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Energy Distribution Ratio into Micro EDM Electrodes

Energy distribution ratio into micro EDM electrodes was determined based on the summation between the ratio of energy loss due to heat conduction within electrodes and ratio of energy carried away by debris. Ratio of energy loss due to heat conduction was obtained by comparing the measured and calculated temperature rise on electrode after igniting plural pulses discharges. On the other hand, the ratio of energy carried away by debris was calculated based on the measured removal volume. Energy distribution ratio into micro EDM anode and cathode was between 10% and 15% in total which was comparatively lower than that of macro EDM. This is because much larger fraction of the total discharge energy is consumed for the generation and enthalphy increase of the plasma in the early stage of discharge. Besides, unlike macro EDM the energy carried away by debris in micro EDM cannot be ignored compared with the energy lost due to heat conduction. This means, the energy consumption by material removal in micro EDM with regard to the energy distributed into the electrodes is more efficient compared to that of macro EDM.