Ion Flux Research Articles

Microstructure evolution of CdZnTe crystals irradiated by heavy ions

Consideration of irradiation effects is important for in-orbit operation and radiation protection in aerospace applications. The configuration of irradiation defects and their impact on deteriorating the carrier transport properties of CZT crystals need to be clarified. In this study, the microdefect evolution mechanism of CdZnTe (CZT) crystals under 10 MeV Chlorine (Cl) ion irradiation at flux of 1×1010∼1×1012 n·cm-2 are investigated. The stacking faults first appear in the CZT crystal at 4.5×10-4 displacement per atom (dpa), which are categorized into slip-type, gap-type and vacancy-type. In order to hinder the further expansion of stacking fault, S-shaped stacking fault dipole appears. When the dpa reaches 4.5×10-2, the local phase transition occurs in the damage zone to form CuPt-A ordered phase with ZnTe/CdTe periodic arrangement because the fluctuation in local composition and strain caused by cascade collisions. The deterioration of electric field distribution and charge collection caused by irradiation damage layer leads to the decrease of γ-ray detection ability. The energy resolution (ER) of the CZT detector for γ-ray can be maintained at 30.6% when the ion flux accumulates to 1×1012 n·cm-2, revealing high irradiation hardness. Consequently, these findings provide a theoretical basis for the radiation damage recovery of CZT detectors, further demonstrating that CZT crystals are the most competitive new generation of room-temperature nuclear radiation detection materials, and can provide radiation protection strategies for similar compound semiconductor materials.

Understanding and Mastering Multiphysical Fields Toward Dendrite‐Free Aqueous Zinc Batteries

AbstractAqueous zinc batteries (AZBs) have emerged as promising candidates for next‐generation grid‐scale energy storage due to their excellent safety, environmental friendliness, and abundance of Zn metal. However, undesired dendrite growth on Zn anodes, resulting from uneven Zn plating/stripping, leads to poor durability and low Coulombic efficiency, posing significant challenges for the practical application of AZBs. Multiple physical fields, the intrinsic driving force governing the distribution of electrons and ions, significantly impact Zn deposition behavior. The underlying mechanisms and regulation strategies related to this phenomenon has not been fully reviewed. This comprehensive review focuses on revealing the key physical fields influencing Zn deposition (including ionic flux, electric field, stress field, and temperature field) and summarizes the most effective control methods. Each approach is thoroughly scrutinized, highlighting its operational mechanisms, benefits, and limitations. Furthermore, the challenges and potential pathways for developing durable Zn anodes are outlined. Through in‐depth analysis of the influences of multiphysical fields on Zn deposition behavior, this review sets the foundation for enhancing the performance of Zn anodes, thereby supporting the advancement of Zn batteries commercialization.

A synthetic method to assay polycystin channel biophysics.

Ion channels are biological transistors that control ionic flux across cell membranes to regulate electrical transmission and signal transduction. They are found in all biological membranes and their conductive state kinetics are frequently disrupted in human diseases. Organelle ion channels are among the most resistant to functional and pharmacological interrogation. Traditional channel protein reconstitution methods rely upon exogenous expression and/or purification from endogenous cellular sources which are frequently contaminated by resident ionophores. Here, we describe a fully synthetic method to assay functional properties of polycystin channels that natively traffic to primary cilia and endoplasmic reticulum organelles. Using this method, we characterize their oligomeric assembly, membrane integration, orientation, and conductance while comparing these results to their endogenous channel properties. Outcomes define a novel synthetic approach that can be applied broadly to investigate channels resistant to biophysical analysis and pharmacological characterization.

A synthetic method to assay polycystin channel biophysics

Ion channels are biological transistors that control ionic flux across cell membranes to regulate electrical transmission and signal transduction. They are found in all biological membranes and their conductive state kinetics are frequently disrupted in human diseases. Organelle ion channels are among the most resistant to functional and pharmacological interrogation. Traditional channel protein reconstitution methods rely upon exogenous expression and/or purification from endogenous cellular sources which are frequently contaminated by resident ionophores. Here, we describe a fully synthetic method to assay functional properties of polycystin channels that natively traffic to primary cilia and endoplasmic reticulum organelles. Using this method, we characterize their oligomeric assembly, membrane integration, orientation, and conductance while comparing these results to their endogenous channel properties. Outcomes define a novel synthetic approach that can be applied broadly to investigate channels resistant to biophysical analysis and pharmacological characterization.

Piezo1-Mediated Mechanotransduction Contributes to Disturbed Flow-Induced Atherosclerotic Endothelial Inflammation.

Disturbed flow generates oscillatory shear stress (OSS), which in turn leads to endothelial inflammation and atherosclerosis. Piezo1, a biomechanical force sensor, plays a crucial role in the cardiovascular system. However, the specific role of Piezo1 in atherosclerosis remains to be fully elucidated. We detected the expression of Piezo1 in atherosclerotic mice and endothelial cells from regions with disturbed blood flow. The pharmacological inhibitor Piezo1 inhibitor (GsMTx4) was used to evaluate the impact of Piezo1 on plaque progression and endothelial inflammation. We examined Piezo1's direct response to OSS invitro and its effects on endothelial inflammation. Furthermore, mechanistic studies were conducted to explore the potential molecular cascade through which Piezo1 mediates endothelial inflammation in response to OSS. Our findings revealed the upregulation of Piezo1 in apoE-/- (apolipoprotein E) atherosclerotic mice, which is associated with disturbed flow. Treatment with GsMTx4 not only delayed plaque progression but also mitigated endothelial inflammation in both chronic and disturbed flow-induced atherosclerosis. Piezo1 was shown to facilitate calcium ions (Ca2+)influx in response to OSS, thereby activating endothelial inflammation. This inflammatory response was attenuated in the absence of Piezo1. Additionally, we identified that under OSS, Piezo1 activates the Ca2+/CaM/CaMKII (calmodulin/calmodulin-dependent protein kinases Ⅱ) pathways, which subsequently stimulate downstream kinases FAK (focal adhesion kinase) and Src. This leads to the activation of the OSS-sensitive YAP (yes-associated protein), ultimately triggering endothelial inflammation. Our study highlights the key role of Piezo1 in atherosclerotic endothelial inflammation, proposing the Piezo1-Ca2+/CaM/CaMKII-FAK/Src-YAP axis as a previously unknown endothelial mechanotransduction pathway. Piezo1 is expected to become a potential therapeutic target for atherosclerosis and cardiovascular diseases.

Magnetically oriented nanosheet interlayer for dynamic regeneration in lithium metal batteries

Lithium (Li) metal has been recognized as a promising anode to advance the energy density of current Li-based batteries. However, the growth of the solid-electrolyte interphase (SEI) layer and dendritic Li microstructure pose significant challenges for the long-term operation of Li metal batteries (LMBs). Herein, we propose the utilization of a suspension electrolyte with dispersed magnetically responsive nanosheets whose orientation can be manipulated by an external magnetic field during cell operation for realizing in situ regeneration in LMBs. The regeneration mechanism arises from the redistribution of the ion flux and the formation of an inorganic-rich SEI for uniform and compact Li deposition. With the magnetic-field-induced regeneration process, we show that a Li||Li symmetric cell stably operates for 350 h at 2 mA cm-2 and 2 mA h cm-2, ~5 times that of the cell with the pristine electrolyte. Furthermore, the cycling stability can be significantly extended in the Li||NMC full cell of 3 mA h cm-2, showing a capacity retention of 67% after 500 cycles at 1C. The dynamic Li metal regeneration demonstrated here could bring useful design considerations for reviving the operating cells for achieving high-energy, long-duration battery systems.

Plasma Etch of IGZO Thin Film and IGZO/SiO2 Interface Diffusion in Inductively Coupled CH4/Ar Plasmas

ABSTRACTIn this work, the etching characteristics of InGaZnO4 (IGZO) thin films were systemically investigated in inductively coupled CH4/Ar plasmas with various gas ratios, bias voltages, and surface temperatures. The ion flux in the CH4/Ar plasmas was analyzed using bias power and voltage, whereas the relative densities of CH and H radicals were quantified through optical actinometry. The change in CH3 radical density was also estimated based on plasma kinetics analysis. The correlations between the plasma properties and IGZO etch rate were investigated. In CH4/Ar plasmas with CH4 ratios below 80%, the IGZO etch rate increases with a higher CH4 proportion, aligning with the ascending trend of CH3 radical density, which suggests that CH3 radical density acts as a limiting factor (radical‐limited regime). However, the IGZO etch rate decreases when the CH4 ratio exceeds 80%, corresponding to the reduction in ion flux, which indicates that ion flux becomes a limiting factor in this ion‐limited regime. The IGZO etch rate shows a linear relationship with bias voltage and follows the Arrhenius equation with varying surface temperature in plasmas without bias voltage. A spontaneous etch model was proposed based on these relationships. In this model, the IGZO etch rate depends on CH3 radical density and IGZO surface reactivity, where ion bombardment contributes more significantly to surface reactivity than high surface temperature. IGZO thin film was deposited on SiO2 during the fabrication of a 3D stacked ferroelectric field‐effect transistor (FeFET) memory device. The interaction between IGZO and SiO2 during CH4/Ar plasma processing was investigated using time‐of‐flight secondary ion mass spectrometry. The efficacy of removing IGZO atoms that had diffused into the SiO2 network was enhanced when subjected to plasma with a bias voltage, compared to the process without a bias voltage. However, exposure to CH4/Ar plasma resulted in a deeper diffusion of IGZO atoms into the SiO2 network, primarily attributed to ion bombardment rather than elevated surface temperature. A significant improvement in surface smoothness was achieved after IGZO and SiO2 etch by introducing BCl3 into the SiO2 etching chemistry.

Finite Element Analysis of Local pH Variations in Electrolysis with Porous Electrodes, Considering Water Self-Ionization.

A finite element model was developed to simulate ion fluxes and local pH changes within and around porous electrodes during the H2 evolution reaction (HER) in acidic electrolytes. This model is particularly characterized by its ability to simulate scenarios in which the local pH inside and near the cathode exceeds 7, even under bulk acidic conditions (e.g., pH = 1), by considering the self-ionization of water. Steady-state calculations using meshes with an appropriate spatial distribution inside and near the cathode revealed that the relationship between the local pH and the double-layer potential at the interface between the porous catalyst layer and the electrolyte domains changed notably when the local pH exceeded the threshold of 7. By comparing the fluxes of H+ and OH- ions at the interface and using the thickness of the catalyst layer as a variable, we determined that the presence of H+ ions within the pores or the supply of OH- ions from the pores to the interface was responsible for the characteristic change in the local pH observed for the porous electrode. The porous electrode model constructed in this study can potentially serve as a basis that can be extended to a wide range of electrolysis systems, including not only the HER, but also the reduction of CO2, H2O2, and O2, and even oxidation reactions such as the O2 evolution reaction.

Toward a Circular Lithium Economy with Electrodialysis: Upcycling Spent Battery Leachates with Selective and Bipolar Ion-Exchange Membranes.

Recycling spent lithium-ion batteries offers a sustainable solution to reduce ecological degradation from mining and mitigate raw material shortages and price volatility. This study investigates using electrodialysis with selective and bipolar ion-exchange membranes to establish a circular economy for lithium-ion batteries. An experimental data set of over 1700 ion concentration measurements across five current densities, two solution compositions, and three pH levels supports the techno-economic analysis. Selective electrodialysis (SED) isolates lithium ions from battery leachates, yielding a 99% Li-pure retentate with 68.8% lithium retention, achieving relative ionic fluxes up to 2.41 for Li+ over transition metal cations and a selectivity of 5.64 over monovalent cations. Bipolar membrane electrodialysis (BMED) converts LiCl into high-purity LiOH and HCl, essential for battery remanufacturing and reducing acid consumption via acid recycling. High current densities reduce ion leakage, achieving lithium leakage as low as 0.03%, though hydronium and hydroxide leakage in BMED remains high at 11-20%. Our analysis projects LiOH production costs between USD 1.1 and 3.6 per kilogram, significantly lower than current prices. Optimal SED and BMED conditions are identified, emphasizing the need to control proton transport in BMED and improve cobalt-lithium separation in SED to enhance cost efficiency.

Transition metals and oxidation reactions trigger stargate opening during the initial stages of the replicative cycle of the giant Tupanvirus.

Tupanviruses, members of the family Mimiviridae, infect phagocytic cells. Particle uncoating begins inside the phagosome, with capsid opening via the stargate. The mechanism through which this opening takes place is unknown. Once phagocytized, metal ion flux control and ROS are induced to inactivate foreign particles, including viruses. Here, we studied the effect of iron ions, copper ions, and H2O2 on Tupanvirus particles. Such treatments induced stargate opening in vitro, as observed by different microscopy techniques. Metal-treated viruses were found to be non-infectious, leading to the hypothesis that stargate opening likely resulted in the release of the viral seed, which is required for infection initiation. To the best of our knowledge, this is the first description of a giant virus capsid morphological change induced by transition metals and H2O2, which may be important to describe new virulence factors and capsid uncoating mechanisms.

Innovative and environmentally friendly MICP surface curing: Enhancing mechanical and durability properties of concrete

Concrete curing is a critical factor influencing its mechanical properties and durability. Traditional curing methods, such as water curing and plastic film curing, have significant limitations, including high water consumption and environmental pollution. This study introduces Microbial Induced Carbonate Precipitation (MICP) as an innovative, environmentally friendly curing method for ready-mixed concrete, addressing the urgent need for sustainable construction practices. The feasibility of MICP surface curing is investigated through comprehensive mechanical and durability tests, coupled with microscopic analyses to understand the underlying mechanisms. The results demonstrate that MICP curing substantially enhances concrete performance. Compared to traditional water curing, the samples cured using MICP have increased compressive strength and splitting tensile strength by up to 31.69% and 24.66%, respectively. Additionally, MICP surface curing significantly reduced capillary water absorption, electric flux, and chloride ion migration coefficient by 12.83%, 15.50%, and 17.36%, respectively. It is found that the optimal concentration of Ca2+ in the MICP solution initially improves concrete performance, which then diminishes at higher concentrations due to bacterial activity inhibition. Spraying the MICP solution at appropriate intervals and increasing the number of treatments further improved concrete properties by ensuring a more extensive and dense deposition of CaCO3. Microscopic analyses, including XRD, TG, and SEM-EDS, revealed that MICP surface curing leads to the formation of vaterite and calcite, which densely cover and fill microscopic cracks and pores, ensuring adequate hydration and simultaneously enhancing the concrete's mechanical and durability properties. This study concludes that MICP surface curing provides superior performance than traditional methods and offers a more sustainable and environmentally friendly curing method.

Long-lived recurrent fluxes of energetic ions from solar coronal holes

The results of studying the relative abundances and energy spectra of 4He, C, O, and Fe suprathermal ions in particle fluxes from long-lived near-equatorial coronal holes are presented. It was found that the ion energy spectra had a power or exponential form and, in a number of events, increased particle fluxes were observed in the region of ion energies (~0.2–1.5 MeV/nucleon), creating a fracture in the spectra, which may be due to additional ions accelerated beyond 1 au.

GABA Type A receptors expressed in triple negative breast cancer cells mediate chloride ion flux.

Triple negative breast cancer (TNBC) is known for its heterogeneous nature and aggressive onset, limited unresponsiveness to hormone therapies and immunotherapy as well as high likelihood of metastasis and recurrence. Since no targeted standard treatment options are available for TNBC, novel and effective therapeutic targets are urgently needed. Ion channels have emerged as possible novel therapeutic candidates for cancer therapy. We previously showed that GABAA β3 subunit are expressed at higher levels in TNBC cell lines than non-tumorigenic MCF10A cells. GABAA β3 subunit knockdown causes cell cycle arrest in TNBC cell lines via decreased cyclin D1 and increased p21 expression. However, it is not known if the upregulated GABAAR express at the cell-surface in TNBC and mediate Cl- flux. Cl- ions are known to play a role in cell-cycle progression in other cancers such as gastric cancer. Here, using surface biotinylation and (N-(Ethoxycarbonylmethyl)-6-Methoxyquinolinium Bromide) MQAE-dye based fluorescence quenching, we show that upregulated GABAAR are on the cell-surface in TNBC cell lines and mediate significantly higher chloride (Cl-) flux as compared to non-tumorigenic MCF10A cells. Moreover, this GABAAR mediated Cl- flux can be modulated by pharmacological agents and is decreased in TNBC cells with GABAA β3 subunit knockdown. Further, treatment of TNBC cells with bicuculline, a GABAAR antagonist reduced cell viability in TNBC cells Overall, these results point to an unexplored role of GABAAR mediated Cl- flux in TNBC.

Generation of multiply charged metal ions in a high current short pulse vacuum arc

We have studied the plasma composition of a high current short pulse vacuum arc discharge with different cathode materials: lanthanum, gadolinium, lead, silver, and tin. We find that for optimal vacuum arc discharge parameters – arc current pulse duration about 2 μs and amplitude about 3 kA – the maximum ion charge state is 11+ and mean ion charge state from 7.8+ for tin to 9.6+ for lanthanum. The mean ion charge state for different materials depends on the discharge voltage and the energy required for ionization to maximum charge state. The cathode surface heats to a temperature of 700 °C–1100 °C in the course of the arc current pulse, depending on the cathode material, and the cathode surface of low melting point metals such as lead and tin melts to a depth of 5 μm and 10 μm, respectively. Surface melting does not lead to change in plasma ion composition, since the ion flux from the cathode considerably exceeds the evaporated atom flux.

Tailoring Zn2+ Flux by an Ion Acceleration Layer Modified Separator for High-Rate Long-Lasting Zn Metal Anodes.

A large concentration gradient originating from sluggish ion transport on the surface of Zn metal anodes will result in uneven Zn2+ flux, giving rise to severe dendrite growth, especially at high current density. Herein, an ion acceleration layer is introduced by a facile separator engineering strategy to realize modulated Zn2+ flux and dendrite-free deposition. Zinc hexacyanoferrate as the modifying agent featuring strong zincophilicity and rapid diffusion tunnel can enable fast trap for Zn2+ near the electrode surface and immediate transport onto deposition sites, respectively. The ion acceleration effect is substantiated by improved ion conductivity, decreased activated energy, and promoted Zn2+ transference number, which can moderate concentration gradient to guide homogenous Zn2+ flux distribution. As a result, the separator engineering guarantees Zn||Zn symmetrical cells with long-term stability of 2700 h at 2 mA cm-2, and 1770 h at a large current density of 10 mA cm-2. Moreover, cycling stability and rate capability for full cells with different cathodes can be substantially promoted by the modified separator, validating its superior practical feasibility. This study supplies a new scalable approach to tailoring ion flux near the electrode surface to enable robust Zn metal anodes at a high current density.

Berberine and palmatine, acting as allosteric potential ligands of α7 nAChR, synergistically regulate inflammation and phagocytosis of microglial cells.

Berberine and palmatine are isoquinoline quaternary alkaloids derived from Chinese medicinal herbs. These alkaloids have shown promising synergy in inhibiting acetylcholinesterase (AChE), indicating their potential in treating Alzheimer's disease (AD). Besides, the anti-inflammatory effects of berberine and palmatine have been widely reported, although the underlying mechanism remains unclear. Here, we found that berberine and palmatine could induce calcium ion (Ca2+) influx via activating α7 nicotinic acetylcholine receptor (α7 nAChR) in cultured microglial cells, possibly serving as its allosteric potential ligands. Furthermore, we examined the synergistic anti-inflammatory effects of berberine and palmatine in the LPS-induced microglia, that significantly suppressed the production of TNF-α and iNOS. Notably, this suppression was reversed by co-treatment with a selective antagonist of α7 nAChR. Moreover, the alkaloid-induced microglial phagocytosis was shown to be mediated by the induction of Ca2+ influx through α7 nAChR and subsequent CaMKII-Rac1-dependent pathway. Additionally, the combination of berberine and palmatine, at low concentration, protected against the LPS-induced endoplasmic reticulum stress and mitochondrial dysfunction in microglia. These findings indicate the potential of berberine and palmatine, either individually or in combination, in contributing to anti-AD drug development, which provide valuable insights into the mechanisms by which natural products, such as plant alkaloids, exert their anti-AD effects.

Coexistence of H-MAR and N-MAR in divertor simulation experimental module of GAMMA 10/PDX

In a divertor simulation experimental module (D-module) of GAMMA 10/PDX, additional hydrogen seeding induces molecular-activated recombination (H-MAR). However, when seeding of hydrogen and nitrogen is combined, Nitrogen MAR (N-MAR) is observed in D-module. In this work, we experimentally investigate plasma detachment processes in D-module by seeding hydrogen-only and hydrogen + nitrogen in order to de-couple MARs contribution to the measured particle flux reduction. Nitrogen is seeded after the electron density, measured with Langmuir probes installed in D-module, begins to decrease due to hydrogen seeding. In both cases, the electron temperature near the V-shaped target decreases from ∼23 eV to ∼2 eV. A clear rollover is observed in the ion flux to the V-shaped target. When only hydrogen is seeded, the Balmer lines emission ratio (i.e. the intensity of Hα emission line (IHα)/the intensity of Hβ emission line (IHβ)), an indicator of H-MAR, is observed to increase between V-shaped targets installed in D-module as the amount of hydrogen gas increases. However, when both hydrogen and nitrogen are seeded, IHα/ IHβ increase is suppressed, and the region of the largest IHα/ IHβ signal shifts upstream of D-module, as observed by a high-speed camera. These results show for the first time the transition from H-MAR-dominated phase to N-MAR-dominated phase and the coexistence of both MARs in D-module. It is found that nitrogen seeding increases plasma detachment even at already relatively low Te (∼5 eV). The high-speed camera measurements suggest this effect to be related to the increase of NHx neutral density, in line with previous modeling works.

Efficient Li+/Mg2+ separation by two-dimensional montmorillonite membrane with stable channel structure through ion exchange and metal–organic coordination strategy

Two-dimensional (2D) nanochannel membranes stacked by nanosheets are promising membrane separation materials. However, intrinsic swelling properties of 2D membrane have emerged as a significant challenge to establish stable nanochannels and achieve high separation performance. Inspired by the natural ion exchange property of montmorillonite (MMT), we constructed a two-dimensional MMT membrane with robust nanochannels by exchanging Fe3+ into interlayer of the membrane, and further achieved efficient separation of Li+/Mg2+ through coordination manipulation of tannic acid (TA) and Fe3+. Swelling was dramatically prevented by strong interlayer interaction between exchanged Fe3+ and nanosheets resulting in a 32-fold increase in anti-swelling properties. Furthermore, experiments and simulations revealed that TA could rapidly chelate with Fe3+ to form a dense hydrophilic functional layer on the membrane interface, which endowed MMT membranes with enhanced mechanical strength, cation transport and recognition, as well as anti-fouling properties. Consequently, the resulting MMT membranes showed the Li+/Mg2+ selectivity as high as 9.98 with a fast Li+ permeation rate (0.108 mol m-2h−1), which exceeded most of the previously reported membranes. This study proposed a novel strategy to diminish the trade-off effect among stability, ion flux, and selectivity of membranes, and inspired the development of next-generation ion selective separation membranes.

Reversible Li plating regulation on graphite anode through a barium sulfate nanofibers-based dielectric separator for fast charging and high-safety lithium-ion battery

Poor Li plating reversibility and high thermal runaway risks are key challenges for fast charging lithium-ion batteries with graphite anodes. Herein, a dielectric and fire-resistant separator based on hybrid nanofibers of barium sulfate (BS) and bacterial cellulose (BC) is developed to synchronously enhance the battery’s fast charging and thermal-safety performances. The regulation mechanism of the dielectric BS/BC separator in enhancing the Li+ ion transport and Li plating reversibility is revealed. (1) The Max-Wagner polarization electric field of the dielectric BS/BC separator can accelerate the desolvation of solvated Li+ ions, enhancing their transport kinetics. (2) Moreover, due to the charge balancing effect, the dielectric BS/BC separator homogenizes the electric field/Li+ ion flux at the graphite anode-separator interface, facilitating uniform Li plating and suppressing Li dendrite growth. Consequently, the fast-charge graphite anode with the BS/BC separator shows higher Coulombic efficiency (99.0% vs. 96.9%) and longer cycling lifespan (100 cycles vs. 59 cycles) than that with the polypropylene (PP) separator in the constant-lithiation cycling test at 2 mA cm−2. The high-loading LiFePO4 (15.5 mg cm−2)//graphite (7.5 mg cm−2) full cell with the BS/BC separator exhibits excellent fast charging performance, retaining 70% of its capacity after 500 cycles at a high rate of 2 C, which is significantly better than that of the cell with the PP separator (retaining only 27% of its capacity after 500 cycles). More importantly, the thermally stable BS/BC separator effectively elevates the critical temperature and reduces the heat release rate during thermal runaway, thereby significantly enhancing the battery’s safety.

Spontaneous asymmetry effect induced by uniform magnetic fields in capacitively coupled plasmas under perfectly symmetric conditions

Abstract Introducing asymmetry in capacitively coupled plasmas (CCPs) is a common strategy for achieving independent control of ion mean energy and flux. Our 1d3v particle-in-cell/Monte Carlo collision simulations reveal that a uniform magnetic field within a specific range can induce spatial asymmetry in low-pressure CCPs, even under perfectly symmetric conditions. This asymmetry, characterized by a shift in the plasma density distribution and significant differences in electron kinetics between the two sides of the plasma, leads to strong ionization and most electron losses on the low-density side, while the high-density side experiences weak ionization and minimal electron losses. The underlying mechanism triggering this spontaneous asymmetry is the differential influence of the magnetic field on low-energy (local) and high-energy (relatively nonlocal) electrons. Under conditions of low pressure and an appropriate magnetic field, this disparity in electron kinetic behavior leads to a spontaneous amplification of the asymmetry induced by random fluctuations until a steady state is reached, culminating in a spontaneous asymmetric effect.