Faraday Cage Research Articles

Investigation of a Radiofrequency Plasma Generator for Multi-Second Pulse Operation

This paper presents the test results of a radiofrequency (RF) plasma generator, developed for neutral beam injectors. A water cooled faraday screen is installed into the generator for multi-second pulse operation. Consistent operation achieved for 20-second long pulses with input power of 38 kW is described. The density of the ion current was measured. The experiments were conducted to measure the density of the ion current at the driver’s output and to evaluate the heating of the driver’s elements. Main factors affecting the power losses were determined. The power loss caused by the eddy currents in the driver’s clamping flanges were reduced.

Electric Discharge in Erupting Mud

AbstractSelf‐ignition during the explosive eruption of mud volcanoes can create flames that in some cases reach heights that exceed hundreds of meters. To study the controls on electrical discharge in natural mud, we performed laboratory experiments using a shock‐tube apparatus to simulate explosive eruptions of mud. We vary the water content of the mud and proportions of fine particles. We measure electric discharge within a Faraday cage and we use a high‐speed video camera to image the eruption of mud and some of the electric discharge events. We find that (a) decreasing the proportion of fine particles and (b) increasing water content each suppress the number and magnitude of electric discharge events. Experimentally observed mud volcano lightning occurs where particles exit from the vent and within the jet of erupting particles.

Fucoidan/κ-carrageenan mixed gel: Effect of anions of different valence including chloride, bromide, iodide, sulfate and phosphate

The effects of the differently charged anions, NaCl, NaBr, NaI, Na2SO4, and Na3PO4 on the gel properties and structure of the fucoidan/κ-carrageenan mixed gel (FC) were investigated using the rheometer, texture analyzer, LF-NMR, Cryo-SEM, FT-IR, and XRD. At a certain concentration, Cl− and Br− could stabilize the helical conformation of the gel through electrostatic shielding. The addition of SO42− and PO43− would reduce the strength of the gel. And I− would soften the gel. With increasing anion concentration, the electrostatic repulsion between FUC and KC was gradually enhanced. The FUC dispersions remained liquid after the addition of anions, while FC gelled depending on the type and concentration of anions. The elastic modulus increased with increasing concentration of NaCl and NaBr, but decreased with increasing concentration of NaI, Na2SO4, and Na3PO4. Moreover, the addition of anions promoted the water migration of FC, as reflected by the T23 relaxation time changing from high to low and the significantly higher migration of NaCl and NaBr than NaI and Na2SO4. The pores of the gel microstructure change from disordered to uniform. The FT-IR and XRD results were well related to the structural changes. There is electrostatic repulsion between anion and FC, and the binding ability of FC to monovalent anions and trivalent anions is better than that of divalent anions. Overall, this study could provide a theoretical basis for the design and development of FUC-based gels.

Surface electrostatics dictate RNA-binding protein CAPRIN1 condensate concentration and hydrodynamic properties

Biomolecular condensates concentrate proteins, nucleic acids, and small molecules and play an essential role in many biological processes. Their formation is tuned by a balance between energetically favorable and unfavorable contacts, with charge-charge interactions playing a central role in some systems. The positively charged intrinsically disordered carboxy-terminal region of the RNA-binding protein CAPRIN1 is one such example, phase separating upon addition of negatively charged ATP or high concentrations of sodium chloride (NaCl). Using solution NMR spectroscopy, we measured residue-specific near-surface electrostatic potentials (ϕENS) of CAPRIN1 along its NaCl-induced phase separation trajectory to compare with those obtained using ATP. In both cases, electrostatic shielding decreases ϕENS values, yet surface potentials of CAPRIN1 in the two condensates can be different, depending on the amount of NaCl or ATP added. Our results establish that even small differences in ϕENS can significantly affect the level of protein enrichment and the mechanical properties of the condensed phase, leading, potentially, to the regulation of biological processes.

Influence of wire spacing and plate spacing on electrostatic precipitation of nanoparticles: An approach involving electrostatic shielding and diffusion charging

Electrostatic precipitation is a process widely used as gas cleaning device, to removal particles from gas flows. However, in a conventional and well-sized precipitator, the collection efficiency decreases for ultrafine particles, making it difficult to employ this equipment for controlling nanoparticle pollution. This paper investigates the influence of plate spacing (4 and 6.5 cm) and wire spacing (4, 6, and 12 cm) on the electric current and nanoparticle collection efficiency, considering the effect of diffusion charging and electrostatic shielding. Two laboratory-scale dry wire-plate electrostatic precipitators with different plate spacings were tested for the collection of nanoparticles (6.15–241.4 nm) at three air velocities (1.9, 2.9, and 3.9 cm/s). The results demonstrated the effectiveness of the equipment in removing nanoparticles (99.9%) under the highest electric fields. Higher values of the wire spacing led to increases in the current and the collection efficiency. This was associated with reduced electrostatic shielding, which is more evident in smaller ducts with a higher density of field lines. It is expected that the findings should improve knowledge on electrostatic precipitation of nanoparticles, enabling optimization of collection efficiency by considering the effects of geometric parameters.

Organic-inorganic hybrid network to enhance the electrostatic shielding of multifunctional soybean meal-based adhesive

Static electricity and formaldehyde pollution are not only severely harmful to ecological environment but also seriously affecting human health. It is of great importance but still challenging to develop an eco-friendly and multifunctional adhesive for electrostatic shielding. Protein adhesives were considered to be an effective substitute for formaldehyde resin adhesives, but show poor water resistance and conductive, limiting their practical applications in many fields, such as antistatic materials and antistatic floors. Therefore, this study aimed to develop a multifunctional adhesive by a facile organic-inorganic hybrid network to enhance the electrostatic shielding for antistatic materials. As we expected, the volume resistivity of the resultant adhesive for antistatic floors is only 2.73 × 10 8 Ω·cm, which is five orders of magnitude less than that of soybean meal (SM) adhesive and shows excellent electrostatic shielding performance. After experiencing a rapid thermal shock cycle between two extreme temperature conditions for 30 times, the mechanical performance of adhesive still remained stable. Furthermore, the adhesives are not only eco-friendly and non-formaldehyde, but excellent mildew resistance and flame retardancy. This multifunctional SM-based adhesive opens a new way to replace harmful formaldehyde-based adhesives, which have potential applications in the field of antistatic floors. • A high-performance adhesive was prepared by a facile and green organic-inorganic hybrid strategy for electrostatic shielding. • The multiple bonding structures were formed between protein chains and hydroxylated BT nanoparticles. • The adhesive exhibited mechanical stability under two extreme temperature cycling. • This adhesive could be used for antistatic materials with flame retardance and antimicrobial properties.

Introducing KI as a functional electrolyte additive to stabilize Li metal anode

A lithium metal battery (LMBs) is an excellent battery system for advanced electrochemical energy storage. However, the growth of lithium dendrites, the accumulation of inactive lithium, and the side reactions between lithium metal and electrolytes limit the cycling stability of LMBs. Herein, we introduce KI additive into lithium bis(trifluoromethanesulfonyl)imide (LiTFSI)/ether-based electrolyte and lithium hexafluorophosphate (LiPF6)/ester-based electrolyte for cycling stability improvement of LMBs. Cu-mesh@Ag||Li half-cell with 0.01 M KI additive exhibits a Coulombic efficiency as high as 98.8 % over 200 cycles. The improved performance due to the electrostatic shielding effect formed by K+ at low concentration and the rapid recovery of inactive lithium by iodine redox. The corresponding Li||Li symmetrical cell shows an outstanding lifespan of 1400 h at 1.0 mA cm−2 with 1.0 mAh cm−2. Meanwhile, in the 1 M LiTFSI + 0.01 M KI electrolyte, the Cu-mesh@Ag-Li||LiFePO4 (LFP) full cell holds capacity retention of 91.7 % over 800cycles at 2.0 C, the Li||LiNi0.8Co0.1Mn0.1O2 (NCM811) full cell possesses much better capacity retention of 54 % after 500 cycles at 1.0 C. This work offers a cost-effective proposal to improve application potential with the electrolyte engineering of rechargeable Li metal batteries.

Hybrid high-performance aqueous batteries with potassium-based cathode||zinc metal anode

Aqueous potassium-based batteries (APBs) have been widely studied for their high safety and environmentally friendly properties. However, given the limitation of the electrode material and working mechanism, the APBs need further improvement in terms of the rate performance and energy density to meet the development requirements. To address the above issues, we successfully designed and assembled APBs, for the first time using Zn metal as the anode, K1.92Cu0.62Mn0.38[Fe(CN)6]0.968·□0.032·0.35H2O as the cathode, and 2 mol L−1 Zn(SO3CF3)2 + 12 mol L−1 KSO3CF3 as the electrolyte. This hybrid-ion-battery (HIB) design offers benefits including the following: (i) improvement of the working potential of APBs by selecting Zn metal as the anode, (ii) shortened ion transport path due to the dual-cation storage mechanism, and (iii) inhibition of the growth of zinc dendrite through the electrostatic shielding effect enabled by K+, which originated from the dual-cation electrolyte. As a result, the as-assembled full battery had a high working potential of 1.75 V and excellent rate performance (83.3% of original capacity was maintained at the current density of 10,000 mA g−1). Furthermore, the in-situ electrostatic shielding effect, which can significantly inhibit the dendrite growth of the Zn anode and improve the stability of the full battery, was fully revealed by theoretical phase-field simulation and comprehensive characterizations. The fascinating structure design of HIBs sheds light on the development of high-performance APBs.

Cryogenic electronics for noble liquid neutrino detectors

In this paper we present the general features of cryogenic (or “cold”) electronics for noble liquid time projection chambers, with design principles and details for neutrino physics, a brief history of the technology and details of recent research and development that is driving the design of the detectors under construction. Finally, some comments on future R&D envisioned and the impact of this work on other fields is described. “Cold” in the context of this work applies to CMOS devices operated at 77 K and above, at liquids temperatures of LAr (89 K), LKr (125 K) and LXe (165 K), with most of the tests performed in, or at LN2 (77 K). The paper is concentrated on the design of cold electronics for large liquid argon TPCs, those that have been successfully operated, MicroBooNE and ProtoDUNE, and those designed or under construction, such as SBND and DUNE first and second 10 kton modules. The high performance achieved with MicroBooNE and ProtoDUNE – a high signal-to-noise ratio combined with high stability of response – is mainly due to the integral approach to design and construction of sensing electrodes with cold readout electronics in a modular approach with the cryostat signal feed-throughs incorporating warm interface electronics into a Faraday cage with the cryostat. The integral concept is described in some detail in this paper.

How External Electric Field Modulates the Rotation Energy Profiles of Dipolar Dopants Inside C70: A Theoretical Interpretation with Electrostatic Shielding Effect Incorporated

AbstractEndohedral fullerenes, which can switch between distinct states with different geometries when triggered by external electric fields (EFs), can be used as logical devices at the molecular scale. However, the movement of electrons around fullerenes exerts an electrostatic shielding effect which alleviates the Coulomb force experienced by endohedral dopants, and thus must be properly evaluated for better elucidating the switching mechanism. Here we introduced new components to the energy decomposition scheme based on the block‐localized wavefunction method (i. e., BLW‐ED), to incorporate the shielding effect explicitly. We analyzed the external EF‐driven rotation of enclosed dipolar molecules inside C70 and evaluated the magnitudes of shielding in terms of the gradients of electrostatic potential and energy. In the absence of external EF, intrinsic rotational barriers are dominated by the Pauli exchange repulsion between enclosed molecules and C70. When an external EF was applied, computations showed that only about 18% of external EFs can penetrate into the cage and interact with dipolar molecules. Thus, the shielding effect dramatically reduces the energy contribution originated from the interaction between endohedral dopants and external EFs. BLW‐ED analyses were further performed to inspect the effect of external EFs on the potential energy surfaces associated with the molecular rotation processes. Indeed, the interaction between penetrated EFs and enclosed molecules can still govern the orientational preferences of dipolar molecules and lower the rotational barrier for some dipolar molecules. But for other molecules, both the intrinsic electrostatic interaction and the Pauli repulsion respond to external EFs more sensitively and rule the changes of barrier heights and orientational preferences.

Molecular dynamics simulations on K2SO4 nucleation in supercritical water

K2SO4 nucleation in supercritical water was investigated by molecular dynamics simulation. The clustering process of K2SO4 was studied for 1 ns in the temperature range of 573–1073 K and in the pressure range of 22–28 MPa. Binding energies, radial distribution functions, and hydrogen bond network analyses showed that temperature and density played significant roles in the nucleation process. With temperature increasing, electrostatic interactions among water molecules and hydrated K+ and SO42− were weakened, so resulting in the reduction of binding energies. Hydrogen bond network was destroyed under supercritical conditions. In addition, high temperature improved the diffusion coefficient of ions. K+ and SO42− could break through the electrostatic shielding effect of water molecules and tended to collide with each other to form ion pairs. The collision of small clusters or ion pairs further produced larger clusters. Moreover, high temperature and low density contributed to the formation of dispersed small clusters.

Purity prediction of the two‐stage high voltage electrostatic separation of a mixture of three polymers

AbstractClean and efficient separation is an important requirement for the high‐value‐added recycling of end‐of‐life automobile polymers. In this study, polymer particles for vehicles were considered as research objects, and a two‐stage electrostatic separation device was designed to separate a mixture of three polymer particles. A kinematic model of friction‐charged particles in a two‐stage free‐fall separator was established. Then, a suitable time period for triboelectrostatic charging with regard to electrostatic separation was determined, and a charge–mass ratio distribution of mixed‐polymer particles, that is, polyamide (PA), polypropylene (PP), and polyethylene (PE), was measured using a Faraday cage based on the triboelectrostatic charging experiment of three types of particles in a friction barrel‐type tribocharger. The theoretical purities of PA, PP, and PE were calculated using the motion and particle charge–mass ratio distribution models were 100.00%, 89.51%, and 92.95% respectively. The experimental purities of PA, PP, and PE were 94.68%, 80.76%, and 84.27%, respectively, which is consistent with the theoretical purity. Results of the study can provide a theoretical and experimental reference for one‐pass electrostatic separation of three kinds of plastic particles.

Investigating the effects of ion strength on amyloid fibril formation of rice proteins

Protein fibrillation is recognized as an attractive strategy to broaden and improve the function of food proteins. This research investigated the influence of different NaCl concentrations (0–210 mM) on the thermal aggregation behavior of rice proteins (RP) at pH 2.0. Under lower (<100 mM) and higher (>100 mM) NaCl concentrations, RP formed aggregates with different sizes and structures. At lower concentrations, the zeta-potential of RP increased from 14.3 mV to 22.8 mV during incubation, indicating that the electrostatic repulsion of RP was enhanced and numerous positively charged building blocks were generated. The circular dichroism (CD) results indicated that the native structure of RP was destroyed after heating at 90 °C for 24 h, and a secondary structure dominated by β-sheets (more than 50%) was formed. Proteins formed long fibrils after 24 h heating, as observed by atomic force microscope (AFM). However, at higher NaCl concentrations, the hydrophobic interaction was the dominant force due to electrostatic shielding. The protein aggregated randomly to form amorphous aggregates with particle sizes over 600 nm. This study will provide a new insight of RP-based fibrils in food application.

The Influence of Grain Size Distribution on Laboratory‐Generated Volcanic Lightning

AbstractOver the last decades, remote observation tools and models have been developed to improve the forecasting of ash‐rich volcanic plumes. One challenge in these forecasts is knowing the properties at the vent, including the mass eruption rate and grain size distribution (GSD). Volcanic lightning is a common feature of explosive eruptions with high mass eruption rates of fine particles. The GSD is expected to play a major role in generating lightning in the gas thrust region via triboelectrification. Here, we experimentally investigate the electrical discharges of volcanic ash as a function of varying GSD. We employ two natural materials, a phonolitic pumice and a tholeiitic basalt (TB), and one synthetic material (soda‐lime glass beads [GB]). For each of the three materials, coarse and fine grain size fractions with known GSDs are mixed, and the particle mixture is subjected to rapid decompression. The experiments are observed using a high‐speed camera to track particle‐gas dispersion dynamics during the experiments. A Faraday cage is used to count the number and measure the magnitude of electrical discharge events. Although quite different in chemical composition, TB and GB show similar vent dynamics and lightning properties. The phonolitic pumice displays significantly different ejection dynamics and a significant reduction in lightning generation. We conclude that particle‐gas coupling during an eruption, which in turn depends on the GSD and bulk density, plays a major role in defining the generation of lightning. The presence of fines, a broad GSD, and dense particles all promote lightning.

Improved pH stability, heat stability, and functionality of phycocyanin after PEGylation

Phycocyanin (PC), a spirulina-derived protein–chromophore complex, suffers from poor techno-functional properties and is highly susceptible to aggregation and color changes upon heating and pH fluctuations. We tackled these issues by modifying PC via PEGylation. Electrophoresis and Fourier transform infrared spectroscopy proved successful conjugation of methoxy PEG (mPEG) chains on PC after PEGylation. Circular dichroism indicated highly ordered folding states adopted by PEGylated PC, which we attributed to the mPEG chains on the protein surface that sterically stabilized the protein structure. Consequently, the mPEG–PC conjugates exhibited high blue color intensity and improved thermodynamic stability. Further, benefit from an electrostatic shielding effect of mPEG chains, surface charges of PEGylated PC were neutralized over pH 2–9 and the blue hue of PC was stabilized against pH variations. Additionally, the flexible and hydrophilic mPEG polymers on the PC surface promoted protein–protein and protein–water interactions. PEGylated PC thus gained increased protein solubility, techno-functionality (emulsifying, foaming, and gelling performance), and antioxidant activities, when compared to unmodified PC. Heat-induced gels formed by mPEG–PC conjugates exhibited increased stiffness, higher water retention, and weak gel-type rheological properties. After PEGylation, the improved functional properties, bioactivity, and color stability against heat and pH fluctuations will facilitate food and pharmaceutical applications of PC.

Variability of coil inductance measurements inside an interleaving structure

The present article is a continuation of our previous works on the anomalies in the decay rates and the capacitance measurements inside a modified Faraday cage. Here we present the anomalous variations in the measurements of inductance when a coil is placed inside an interleaving structure of metal and organic material. The fluctuation in the inductance values was found to be in the range − 0.007 to 0.018 mH. Additionally, it was observed that the temperature coefficient which was 0.0062 mH/°C initially jumped to two distinct levels, 0.0095 mH/°C and 0.0145 mH/°C, respectively. A multiple factor analysis of our results revealed a very strong correlation (R2 = 95.2%) between the inductance and the combination of the temperature and the relative humidity both measured inside the cage, next to the inductor.

Halogenated Zn2+ Solvation Structure for Reversible Zn Metal Batteries.

Rechargeable aqueous Zn metal batteries have become promising candidates for large-scale electrochemical energy storage owing to their high safety and affordable low cost. However, Zn metal anode suffers from dendritic growth and hydrogen evolution reaction (HER), deteriorating the electrochemical performance. Here, we demonstrate that these challenges can be conquered by introducing a halogen ion into the Zn2+ solvation structure. By designing an electrolyte composed of zinc acetate and ammonium halide, the electron-donating anion I- can coordinate with Zn2+ and transform the traditional Zn(H2O)62+ to ZnI(H2O)5+, in which I- could transfer electrons into H2O and thus suppress HER. The dynamic electrostatic shielding layer formed by concomitant NH4+ can restrict the dendritic growth. As a result, the halogenated electrolyte achieves a high initial coulombic efficiency (CE) of 99.3% in the Zn plating/stripping process and remains at an average of ∼99.8% with uniform Zn deposition. Moreover, Zn-I batteries are constructed by using dissociative I- as the cathode and carbon felt-polyaniline as the conductive and adsorptive layer, exhibiting an average CE of 98.6% without capacity decay after 300 cycles. This work provides insights into the halogenated Zn2+ solvation structure and offers a general electrolyte design strategy for achieving a highly reversible Zn metal anode and batteries.

Triazine crosslinked polyionic liquid: An electrolyte-stable, lithiophilic and electrostatic shielding layer for uniform lithium plating/stripping

Rational design of functional layer on Cu current collector with polymer material is an effective strategy to improve electrochemical performance of batteries with Li anode. Here, a multifunctional solvent-stable layer, which contains triazine crosslinked polyionic liquid (cPIL) as the polymer matrix and in-situ formed LiF nanoparticle as filler (cPIL-LiF), is constructed on Cu foil to regulate the plating/stripping behavior of Li. The cPIL with excellent lithiophilicity and electrostatic shielding performance ensures homogeneous Li+ flux and promotes uniform Li deposition. The LiF nanoparticles and TFSI anions in cPIL-LiF contribute to the formation of the stable LiF- and Li3N-rich solid electrolyte interphase (SEI). Due to these superiorities, excellent interfacial stability is achieved and, consequently, dense and dendrite-free Li deposition is well maintained during cycling. The cPIL-LiF coated Cu enables an improved cycling stability with coulombic efficiency of ∼98% for 200 cycles, much better than the bare Cu and the Cu modified with the commonly used polymers. Moreover, the full cells with Li4Ti5O12/LiFePO4 cathodes and cPIL-LiF-Cu@Li (limited amount of deposited Li) demonstrate apparently enhanced electrochemical performance. This work provides new perspectives to construct electrolyte-stable artificial protective layer on Cu current collector for stable Li plating/stripping and enriches the understanding on the development of high-performance Li metal-based batteries.

Recording of pig neuronal activity in the comparative context of the awake human brain

Gyriform mammals display neurophysiological and neural network activity that other species exhibit only in rudimentary or dissimilar form. However, neural recordings from large mammals such as the pig can be anatomically hindered and pharmacologically suppressed by anesthetics. This curtails comparative inferences. To mitigate these limitations, we set out to modify electrocorticography, intracerebral depth and intracortical recording methods to study the anesthetized pig. In the process, we found that common forms of infused anesthesia such as pentobarbital or midazolam can be neurophysiologic suppressants acting in dose-independent fashion relative to anesthetic dose or brain concentration. Further, we corroborated that standard laboratory conditions may impose electrical interference with specific neural signals. We thus aimed to safeguard neural network integrity and recording fidelity by developing surgical, anesthesia and noise reduction methods and by working inside a newly designed Faraday cage, and evaluated this from the point of view of neurophysiological power spectral density and coherence analyses. We also utilized novel silicon carbide electrodes to minimize mechanical disruption of single-neuron activity. These methods allowed for the preservation of native neurophysiological activity for several hours. Pig electrocorticography recordings were essentially indistinguishable from awake human recordings except for the small segment of electrical activity associated with vision in conscious persons. In addition, single-neuron and paired-pulse stimulation recordings were feasible simultaneously with electrocorticography and depth electrode recordings. The spontaneous and stimulus-elicited neuronal activities thus surveyed can be recorded with a degree of precision similar to that achievable in rodent or any other animal studies and prove as informative as unperturbed human electrocorticography.

Amphiphile regulated ionic-liquid-based aqueous biphasic systems with tunable LCST and extraction behavior

Ionic liquid (IL)/H2O mixtures with tunable lower critical solution temperature (LCST) behavior exhibit tantalizing prospect in the field of liquid-liquid phase separation and purification. Herein, different types of amphiphiles were evaluated for the facile regulation of IL ([P4444][DMBS]) based aqueous biphasic systems (ABSs). Interestingly, the addition of zwitterionic 3-(1-dodecyl-3-imidazolio) propanesulfonate (DIPS) remarkably increases the phase separation temperature of IL aqueous solution, while the addition of anionic sodium dodecyl benzene sulfonate (SDBS) and dodecyl-benzenesulphonic acid (DBSA) results in decreasing of the phase separation temperature. The tunable phase separation temperature ranges from 10 to 90 °C, which almost cover the full usable temperature range of ABSs. The regulation mechanism of amphiphile additives on the LCST behavior of IL/H2O mixtures was investigated through isothermal titration calorimetry, 1H NMR spectroscopy and molecular dynamics simulations. Briefly, the addition of zwitterionic DIPS increased LCST through electrostatic shielding effect, while the addition of anionic SDBS and DBSA decreased LCST through ion exchange effect. As a proof of concept, the amphiphile regulated ABSs were demonstrated to selectively separate aliphatic and aromatic amino acids.