Short-circuited Configuration Research Articles

Development of a Miniaturized 2-Joule Pulsed Plasma Source Based on Plasma Focus Technology: Applications in Extreme Condition Materials and Nanosatellite Orientation.

Plasma focus devices represent a class of hot and dense plasma sources that serve a dual role in fundamental plasma research and practical applications. These devices allow the observation of various phenomena, including the z-pinch effect, nuclear fusion reactions, plasma filaments, bursts, shocks, jets, X-rays, neutron pulses, ions, and electron beams. In recent years, considerable efforts have been directed toward miniaturizing plasma focus devices, driven by the pursuit of both basic studies and technological advancements. In this paper, we present the design and construction of a compact, portable pulsed plasma source based on plasma focus technology, operating at the ~2-4 Joule energy range for versatile applications (PF-2J: 120 nF capacitance, 6-9 kV charging voltage, 40 nH inductance, 2.16-4.86 J stored energy, and 10-15 kA maximum current at short circuit). The components of the device, including capacitors, spark gaps, discharge chambers, and power supplies, are transportable within hand luggage. The electrical characteristics of the discharge were thoroughly characterized using voltage and current derivative monitoring techniques. A peak current of 15 kiloamperes was achieved within 110 nanoseconds in a short-circuit configuration at a 9 kV charging voltage. Plasma dynamics were captured through optical refractive diagnostics employing a pulsed Nd-YAG laser with a 170-picosecond pulse duration. Clear evidence of the z-pinch effect was observed during discharges in a deuterium atmosphere at 4 millibars and 6 kilovolts. The measured pinch length and radius were approximately 0.8 mm and less than 100 μm, respectively. Additionally, we explore the potential applications of this compact pulsed plasma source. These include its use as a plasma shock irradiation device for analyzing materials intended for the first wall of nuclear fusion reactors, its capability in material film deposition, and its utility as an educational tool in experimental plasma physics. We also show its potential as a pulsed plasma thruster for nanosatellites, showcasing the advantages of miniaturized plasma focus technology.

Characterizing the HERMES-III Extended Magnetically Insulated Transmission Line

Modeling and simulation of the HERMES-III extended magnetically insulated transmission line (MITL) terminated by a diode with an annular cathode and a planar anode was performed with an electromagnetic particle-in-cell code, EMPIRE-PIC. Self-limited MITL theory was developed and implemented in order to model select shots in EMPIRE by allowing one to transform an experimental current trace into a voltage waveform that is input into EMPIRE. Simulating shots 11 132, 11 133, 11 134, 11 135, 11 136, and 11 146 in EMPIRE shows good agreement with experimental current traces at several locations along the MITL. New calibrations for the anode current shunts are proposed based on low-power shots fired into a short-circuited diode configuration (short-shots). The new calibrations show improved agreement with simulation results.

Design of an Ultra-Wideband Using the Stub Q-Factor Technologies, Ended by Short-Circuit Configurations

Design of an Ultra-Wideband Using the Stub Q-Factor Technologies, Ended by Short-Circuit Configurations

Highly sensitive interfaces of graphene electrical-electrochemical vertical devices for on drop atto-molar DNA detection

The development of novel high-sensitivity DNA-based biosensors is beneficial, as these devices have applications in the identification of genetic risk factors, medical diagnostics, and environmental monitoring. Herein, we report on the first robust device capable of detecting DNA on a microliter drop with a zepto-molar (10−21) concentration. To accomplish this, we engineered an electrical-electrochemical vertical device (EEVD) that comprises a novel drain and source terminal in a short-circuited configuration, paired with an ideal non-polarizable reference electrode. Vertical electron transfer occurs perpendicularly to the graphene plane, while the electronic current flows through the graphene van der Waals (vdW) heterojunctions. Ferrocene adsorbed on graphene was strategically chosen as the vdW heterojunction redox component. Charge carrier insertion into the graphene makes the EEVD 10 times more sensitive than traditional graphene field-effect transistors. Interfacial potential changes were measured for single-stranded DNA detection with an unprecedented zepto-molar limit of detection.

S-band electron spin resonance spectroscopy using a short-circuited coplanar waveguide resonator

In this work, we study the development of a coplanar waveguide (CPW) resonator and its use in an electron spin resonance (ESR) spectrometer. The CPW resonator is designed to operate in S-band (2-4 GHz), with a short circuit configuration leading to miniaturization. It is so constructed such that it has a characteristic impedance of 50 ohms. The resonator supports quasi-TEM mode of propagation owing to its uniplanar nature, demanding detailed electromagnetic simulation. The design parameters and the electromagnetic field distribution are obtained from the simulation. The resonator is fabricated using optical lithography with a rapid prototyping technique. The characteristic response of the resonator is measured by coupling it to a Vector Network Analyzer (VNA). The ESR absorption spectrum of free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) is captured by using this resonator in reflection geometry. The microwave magnetic field distribution at the sample position is investigated. The ascertained value of Lande g-factor is consistent with that reported in the literature. Spin sensitivity of the order of 1015 spins/gauss is achieved upon using this resonator at room temperature. The quality factor of this resonator is found to be low and this makes it suitable for use in a Pulsed ESR spectrometer.

Security Promises and Vulnerabilities in Emerging Reconfigurable Nanotechnology-Based Circuits

Emerging nanotechnologies based reconfigurable field-effect transistors (RFETs) allow switching between p-type and n-type behavior at runtime upon application of different bias potentials. While prior works have mainly focused on security schemes using RFETs, here we revisit the underlying security promises, and furthermore, showcase certain circuit vulnerabilities which can lead to adversarial scenarios. More specifically, first, we explore how transistor-level reconfigurability can be leveraged for logic locking and split manufacturing in the pretext of RFET-based modeling of the ITC-99 circuits. We find that with only 30% reconfigurable logic gates, we can induce 100% output error rate (OER) and 31% Hamming distance(HD) on split-manufacturing schemes. Second, which is arguably more disruptive, we explore how the very reconfigurability can be exploited to induce either short-circuit or open-circuit configurations, essentially destroying the reliability, electrical, or functional characteristics of the chip. By means of fault modeling for such exploitation, 100% OER (across all benchmarks) as well as 36.5%, 40.02%, and 6.34% HD, respectively, can be expected for the MCNC, EPFL, and ITC-99 benchmarks. The novelty and severity of such disruptive scenario lies in the fact that they can be readily realized in an actual on-field RFET-based chip, either as an adversarial or a fail-safe measure.

Cylindrical Cam Electromagnetic Vibration Damper Utilizing Negative Shunt Resistance

Two common problems in utilizing electromagnetic dampers are addressed in this article. The first problem is the maximum available damping that can be created in an electromagnetic actuator using a positive resistive load. Maximum damping is achieved when the motor terminals are placed in a short circuit configuration, but it might not be enough in certain applications. As a solution, a method to produce negative resistance using power electronics and control techniques is presented in this article. The negative resistance cancels part of the resistance of the electromagnetic machine, which leads to producing larger electrical current in the actuator coils. As a result, higher damping levels are generated. The other contribution of this article is devising an effective motion rectification mechanism for converting the translational motion into rotary motion that drives an electric machine. To this end, a cylindrical cam mechanism is proposed which can provide longer strokes while keeping the geometry and size of the damper similar to the axial dampers used in automotive and bicycle dampers. The mechanism shows longer values for the ratio of stroke to maximum length compared to other designs reported in the literature.

Dynamic simulation of induced voltages in high voltage cable sheaths: Steady state approach

This paper presents a novel approach to the modeling of high voltage underground cables. Its main contribution is that it considers induced effects. Indeed, it incorporates the estimate of induced voltages and currents in cable sheaths in steady state due to the nearby cables and sheaths, for different types of sheaths connections and for various single-phase short-circuit configurations and three-phase short-circuits. Furthermore, it allows multiple circuits to be coupled automatically in a simple way. An intuitive and friendly simulation tool has been implemented that allows the automatic generation of multiple coupling circuits and to calculate all these induced effects caused by the connection of the sheaths and the distance between cables. It has been validated by comparing it with the expected theoretical data and to other simulators with satisfactory results.

Experimental Evaluation of Novel Hybrid Microwave/Ultrasonic Technique to Locate and Characterize Pipe Wall Thinning

Research using microwaves (MWs) to detect pipe wall thinning (PWT) distinguishes the presence of wall thinning, but does not accurately locate the discontinuities. Ultrasonic testing (UT) is capable of accurately locating the PWT defect, but cannot do so without time-consuming linear scanning. This novel work combines the MW technique as a way to predict the location of a series of PWT specimens, and the UT technique as a way to characterize the PWT specimens in terms of location, depth, and profile shape. The UT probe is guided to the predicted location derived from the Phase One MW results, generating the Phase Two results to determine accurate location, depth measurement, and profile shape detection. The work uses the previously successful experimental setup for testing of an aluminum pipe with 154.051 mm inner diameter (ID) and 1 m length. A vector network analyzer (VNA) generates a MW sweeping frequency range of 1.4–2.3 GHz. This signal is propagated within reference pipes with both open end and short-circuit configurations for calibration of the system. The calibrated system is used to detect the presence and location of six PWT specimens, with two profile shapes, at three depths of thinning and three locations along the pipe. The predicted locations from Phase One are then used to guide a calibrated, manually guided straight beam UT probe to the predicted position. From that point, the UT probe is used in order to accurately localize and determine the depth and shape profile of the specimens.

A Spatially Separated Organic–Inorganic Hybrid Photoelectrochemical Cell for Unassisted Overall Water Splitting

The Z-scheme overall solar water splitting is a mimic of natural photosynthesis to convert solar energy into chemical fuels. Despite much effort, the available Z-scheme artificial systems are still rare, and most of them rely on inorganic semiconductors. In this study, inspired by the characteristics of p-type and higher unoccupied molecular orbital level of organic semiconductors, a spatially separated organic–inorganic hybrid Z-schematic photoelectrochemical (PEC) cell for unassisted overall water splitting is developed by wiring inorganic ZnO nanorod arrays photoanode and organic poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid (P3HT:PCBM) photocathode in a tandem manner. In the short-circuit configuration, the photocurrent density reaches an initial value of ∼78 μA cm–2 and an average value of ∼95 μA cm–2 under continuous UV–vis light irradiation, giving rise to the solar-to-fuel conversion efficiency of ∼0.12%. The average gas evolution rates are 1.59 μmol h–1 for H2 and 0.75 μmol h–1 for O2 unde...

Vibrational assisted conduction in a molecular wire

We present a detailed study of the conduction properties of a molecular wire where hopping processes between electronic sites are coupled to a vibrational mode of the molecule. The latter is sandwiched between two electronic leads at finite temperatures. We show that the electro-mechanical coupling can lead to a strong enhancement of the lead-to-lead conduction. Moreover, under suitable driving of the molecular vibrational mode, the device can act as a transistor passing sharply from enhanced conduction to short-circuit configuration.

A piezo-shunted kirigami auxetic lattice for adaptive elastic wave filtering

Tailoring the dynamical behavior of wave-guide structures can provide an efficient and physically elegant approach for optimizing mechanical components with regards to vibroacoustic propagation. Architectured materials as pyramidal core kirigami cells combined with smart systems may represent a promising way to improve the vibroacoustic quality of structural components. This paper describes the design and modeling of a pyramidal core with auxetic (negative Poisson’s ratio) characteristics and distributed shunted piezoelectric patches that allow for wave propagation control. The core is produced using a kirigami technique, inspired by the cutting/folding processes of the ancient Japanese art. The kirigami structure has a pyramidal unit cell shape that creates an in-plane negative Poisson’s ratio macroscopic behavior. This structure exhibits in-plane elastic properties (Young’s and shear modulus) which are higher than the out-of-plane ones, and hence this lattice has very specific properties in terms of wave propagation that are investigated in this work. The short-circuited configuration is first analyzed, before using negative capacitance and resistance as a shunt which provides impressive band gaps in the low frequency range. All configurations are investigated by using a full analysis of the Brillouin zone, rendering possible the deep understanding of the dynamical properties of the smart lattice. The results are presented in terms of dispersion and directivity diagrams, and the smart lattice shows quite interesting properties for the adaptive filtering of elastic waves at low frequencies bandwidths.

Numerical Investigation on Nonlinear Vibration Behavior of Laminated Cylindrical Panel Embedded with PZT Layers

This work investigates the geometrical nonlinear free vibration characteristic of cylindrical composite shell panel embedded with piezoelectric layers. A short circuit configuration (top and bottom layers are grounded i.e. zero potential) has been considered for the present analysis. A general mathematical model has been developed using higher order shear deformation mid-plane kinematics employing Green-Lagrange type of nonlinearity. Numerical solutions are obtained using Hamilton's principle and discretized isoparametric finite element steps. The validity of present model has been checked by comparing the responses to those available in published literature. In order to examine the efficacy and applicability of the present developed model, few numerical examples are solved for different geometrical parameters (fiber orientation, thickness ratio, aspect ratio, curvature ratio, support conditions and amplitude ratio) with and/or without piezoelectric embedded layers and discussed in details.

A layer-wise MITC9 finite element for the free-vibration analysis of plates with piezo-patches

The present article considers the free-vibration analysis of plate structures with piezoelectric patches by means of a plate finite element with variable through-the-thickness layer-wise kinematic. The refined models used are derived from Carrera’s Unified Formulation (CUF) and they permit the vibration modes along the thickness to be accurately described. The finite-element method is employed and the plate element implemented has nine nodes, and the mixed interpolation of tensorial component (MITC) method is used to contrast the membrane and shear locking phenomenon. The related governing equations are derived from the principle of virtual displacement, extended to the analysis of electromechanical problems. An isotropic plate with piezoelectric patches is analyzed, with clamped-free boundary conditions and subjected to open- and short-circuit configurations. The results, obtained with different theories, are compared with the higher-order type solutions given in the literature. The conclusion is reached that the plate element based on the CUF is more suitable and efficient compared to the classical models in the study of multilayered structures embedding piezo-patches.

SPM characterization of next generation solar cells under light irradiation: Optoelectronic study from nano to macroscopic scale.

Solar cells (SCs) that contain elaborate nanostructures, such as quantum dots and quantum wells, have been rigorously investigated as a way to harvest a wide range of the solar spectrum [1]. However, the energy conversion efficiency of those SCs still remains low. For the further improvement of the device performance, a much deeper understanding of the role of nanostructures in the photovoltaic conversion process is essential to gain the effective design criteria. To achieve this, local electronic properties including electrical potential, energy states, and charge distribution around the excitation centers have to be characterized under light irradiation since they govern the behavior of excited carriers. These properties have so far been indirectly deduced from macroscopic characterization such as current-voltage (I-V) measurement; however, it is not sufficient to clarify rather complicated roles of the nanostructures [2]. Thus, a direct measurement of those properties with high spatial resolution is required to understand the detailed mechanisms of the photovoltaic conversion process. To this end, we have been developing a platform for performing scanning tunneling microscopy/spectroscopy (STM/STS), atomic force microscopy (AFM), and Kelvin probe force microscopy (KPFM) working under light irradiation conditions.Here, we outline the characterization of a multiple quantum well (QW) SC based on III-V compounds that is expected to be a potential candidate of intermediate band type SC. First, we show the electrical potential measurements along the p-i-n junction of the SC using KPFM in air. Measurements were performed in open and short circuit configurations under light irradiation conditions [Fig.1]. We demonstrate that the dependence of the open circuit voltage on the intensity of light can be successfully measured by careful interpretation of the KPFM data. Second, we introduce some examples of the atomic scale characterization of the multiple QW using ultrahigh vacuum STM including the atomic arrangement, electronic states, and band profile. Also, charge accumulation at the QW is discussed based on the topographic measurement under light irradiation.jmicro;63/suppl_1/i12/DFU042F1F1DFU042F1Fig. 1.(a) Schematic illustration of measurement system of KPFM in air. (b) Effect of light irradiation on potential profile in open circuit configuration.

Snapback‐free reverse‐conducting IGBT with low turnoff loss

A novel structure of the reverse-conducting insulated gate bipolar transistor (RC-IGBT) is proposed. The structure is connected anti-parallel with a PNP and an NPN transistor, which are in a collector-base short-circuited configuration. Bidirectional conduction capability with no snapback can be obtained by this structure and the turnoff speed can be much improved. The structure can work in two different modes in a reverse-conducting state: a diode mode and a thyristor mode. Two-dimensional numerical simulation results show that the novel RC-IGBT reduces the turnoff loss ( E off ) by 26.4 and 37.7% for the thyristor mode and the diode mode, respectively, and has no current non-uniformity compared with the conventional RC-IGBT.

A fast-switching light-writable and electric-erasable negative photoelectrochromic cell based on Prussian blue films

We report a fast-switching negative photoelectrochromic cell composed of a dye-sensitized nanocrystalline TiO2 electrode and Prussian blue counter electrode sandwiching a LiI electrolyte. The cell can be bleached under illumination with shorted TiO2 and Prussian blue electrodes, and re-colored by applying an appropriate external voltage. The photo-bleaching and electric-coloring processes are fast and reversible. A maximum absorbance modulation of 0.44 recorded at 700nm is obtained between bleached and colored states for the cell when the PB film's thickness is 452nm. Illuminated under different levels of light intensity or durations of time, the shorted cell shows adjustable optical absorption from 470 to 840nm. The in-situ transmittance response depicts that the photo-bleaching response is 6.2s for 70% transmittance change under 100mW/cm2 illumination in short circuit configuration, and the re-coloration time is about 600ms under 2V bias recorded at 780nm, with an electrochromic coloration efficiency of 103.4cm2/C. The cell shows a good reversible stability and can be potentially applied in erasable displays.

A Wideband VHF/UHF Discone-Based Antenna

Few low-profile VHF/UHF antennas have been reported so far although they are demanded in many applications such as aircraft communication systems. In this letter, a low-profile wideband VHF/UHF antenna based on the conventional discone antenna is proposed. It is composed of a discone antenna that is flattened with additions of a cavity-backed discone, a short-circuited configuration, and a two-plate top structure. The simulation results show that the addition of the three structures makes the proposed antenna low-profile and wideband. A prototype with optimized geometrical parameters was fabricated and tested. The measurements show that the prototype has a VSWR bandwidth of 76% from 200 to 447 MHz, a height of only 0.087λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> , and a radiation pattern of omnidirectivity. The designed antenna has great potential for its flush-mount capability.

Optical and charge transport properties of aCuIn1−xGaxSe2solar cell cross section

In this Rapid Communication we present detailed band-gap profile in a ${\text{CuIn}}_{1\ensuremath{-}x}{\text{Ga}}_{x}{\text{Se}}_{2}$ thin-film solar cell absorber on nanometers scale. Details of the band bending and charge accumulation are resolved in simultaneous measurements of space-resolved photoluminescence spectroscopy and local beam-induced current in open and short circuit configurations. We find strong influence of top interface defects within 700 nm from a top contact and reconstruct a band diagram in the absorber layer. These results provide a different insight into profiles of efficiency relevant parameters in the solar cells.

General adjoint approach to the physics-based noise modeling of semiconductor devices through Langevin sources

A general approach to the numerical analysis of noise in physics-based semiconductor devices is proposed. This approach is based on the Riesz representation theorem and can be applied to most partial-differential-equation-based semiconductor device models. Explicit expressions of Green’s functions for both open-circuit and short-circuit configurations are provided. Our approach is conceptually simpler than Branin’s method developed through the network analogy and it is flexible in the sense that it can be applied to any network configuration without additional matrix transformations. Numerical results of the noise in short-channel metal-oxide-semiconductor field-effect transistors and 4H-Si metal-semiconductor field-effect transistors are presented and discussed.