Single Voltage Pulse Research Articles

Artificial synapse based on low-voltage Ni-doped CuI thin-film transistors for neuromorphic application

Inspired by the human brain's capacity as a powerful biological computer capable of simultaneously processing a vast array of cognitive tasks, many emerging artificial synapse devices have been developed in recent years. Electric-double-layer (EDL) transistors based on interfacial ion-modulation have attracted widespread attention for simulating synaptic plasticity and neural functions. Here, low-voltage EDL p-type thin-film transistors (TFTs) are fabricated on glass substrates, with Ni-doped cuprous iodide (Ni0.06Cu0.94I) as the channel and chitosan as the dielectric. The electrical performance of the Ni0.06Cu0.94I TFTs is investigated: current on/off ratio of 6.4 × 104, subthreshold swing of 33 mV/dec, threshold voltage of 1.38 V, operating voltage of 2 V, and saturation field-effect mobility of 15.75 cm2 V−1 s−1. A dual in-plane gate OR logic operation is demonstrated. Importantly, by applying single voltage pulses, dual voltage pulses, and multiple voltage pulses to the gate, the Ni0.06Cu0.94I transistors exhibited typical synaptic characteristics, including short-term potentiation, short-term depression, long-term potentiation, long-term depression, paired-pulse facilitation, and spiking-rate-dependent plasticity. Furthermore, the synaptic transistor can also simulate the learning–forgetting–relearning process of the human brain. These remarkable behaviors of voltage-stimulated synaptic transistors have potential for neuromorphic applications in future artificial systems.

Time-resolved characteristics of a nanosecond pulsed multi-hollow needle plate packed bed dielectric barrier discharge

In this paper, self-designed multi-hollow needle electrodes are used as a high-voltage electrode in a packed bed dielectric barrier discharge reactor to facilitate fast gas flow through the active discharge area and achieve large-volume stable discharge. The dynamic characteristics of the plasma, the generated active species, and the energy transfer mechanisms in both positive discharge (PD) and negative discharge (ND) are investigated by using fast-exposure intensified charge coupled device (ICCD) images and time-resolved optical emission spectra. The experimental results show that the discharge intensity, number of discharge channels, and discharge volume are obviously enhanced when the multi-needle electrode is replaced by a multi-hollow needle electrode. During a single voltage pulse period, PD mainly develops in a streamer mode, which results in a stronger discharge current, luminous intensity, and E/N compared with the diffuse mode observed in ND. In PD, as the gap between dielectric beads changes from 0 to 250 μm, the discharge between the dielectric bead gap changes from a partial discharge to a standing filamentary micro-discharge, which allows the plasma to leave the local area and is conducive to the propagation of surface streamers. In ND, the discharge only appears as a diffusion-like mode between the gap of dielectric beads, regardless of whether there is a discharge gap. Moreover, the generation of excited states and is mainly observed in PD, which is attributed to the higher E/N in PD than that in ND. However, the generation of the radical in ND is higher than in PD. It is not directly dominated by E/N, but mainly by the resonant energy transfer process between metastable and . Furthermore, both PD and ND demonstrate obvious energy relaxation processes of electron-to-vibration and vibration-to-vibration, and no vibration-to-rotation energy relaxation process is observed.

Short-voltage pulse generation for induction heating load detection on a multi-output inverter with shared power devices

Purpose The purpose of this paper is to develop a load detection method for domestic induction cooktops. The solution aims to minimize its impact in the converter power transmission while enabling the estimation of the equivalent electrical parameters of the load. This method is suitable for a multi-output resonant inverter topology with shared power devices. Design/methodology/approach The considered multi-output converter presents power devices that are shared between several loads. Thus, applying load detection methods in the literature requires a halt in the power transfer to ensuring safe operation. The proposed method uses a complementary short-voltage pulse to excite the induction heating (IH) coil without stopping the power transfer to the remaining IH loads. With the current through the coil and the analytical equations, the equivalent inductance and resistance of the load is estimated. The precision of the method has been evaluated by simulation, and experimental results are provided. Findings The measurement of the current through the induction coil as a response to a short-time single-pulse voltage variation provides enough information to estimate the load equivalent parameters, allowing to differentiate between no-load, non-suitable IH load and suitable IH load situations. Originality/value The proposed method provides a solution for load detection without requiring additional circuitry. It aims for low power transmission to the load and ensures zero-voltage switching and reduced peak current even in no-load cases. Moreover, the proposed solution is extensible to less complex converters, as the half bridge.

Autonomous Light Intensity Adaptation in an Energy‐Efficient Retinomorphic Organic Ferroelectric Neuristor

Autonomous Light Intensity Adaptation in an Energy‐Efficient Retinomorphic Organic Ferroelectric Neuristor

Drastic enhancement of stable and fast domain wall motion in GdFe nanowires through laser-annealing treatment at wire edges

One of the key challenges in racetrack memory (RM) technology is achieving stable and high velocities for domain walls (DWs) while maintaining low power consumption. In our study, we propose a novel laser-annealing (LA) process to modify wire edges for a smoother DW movement along the nanowire. In this regard, a film stack of Pt (5 nm)/Gd26Fe74(20 nm)/SiN(10 nm) was deposited by magnetron sputtering. The DW velocity in the wire was measured by applying single voltage pulses and then observing the DW motion using a Kerr microscope. The current-induced domain walls motion measurements have shown that the LA process significantly enhances the velocity of DW motion. The LA of both edges of the nanowire results in a threefold increase in DW velocity compared to non-LA conditions. Further experiments illustrated that the DW velocity remains stable for the laser-annealed condition across a wide range of applied currents, spanning from 3 × 1011 to 7 × 1011 A/m2. Additionally, our investigation into the magnetic characteristics of laser-annealed nanowire regions exhibited a notable reduction of Hc at the laser-annealed edges. This decrease in Hc indicates greater ease in manipulating the material’s magnetization, which is essential for efficient DW motion. Furthermore, we explored the influence of LA on the Dzyaloshinskii–Moriya Interaction (DMI) field. The DMI finding underscores the strong correlation between DMI fields and DW speed. This achievement, i.e. the stability and consistency of the domain’s velocity (as the components of an RM) in a wide range of applied current, is significant progress in the field of operation and industrialization of RM.

Pulsation mechanism of a Taylor cone under a single pulse voltage

Pulsation mechanism of a Taylor cone under a single pulse voltage

A computational study on the energy efficiency of species production by single-pulse streamers in air

We study the energy efficiency of species production by streamer discharges with a single voltage pulse in atmospheric dry air, using a 2D axisymmetric fluid model. Sixty different positive streamers are simulated by varying the electrode geometry, the pulse duration and the applied voltage. Between these cases, the streamer radius and velocity vary by about an order of magnitude, but the variation in the maximal electric field is significantly smaller, about 30%. We find that G-values for the production of N(4S), O(3P), NO and N2O, which have relatively high activation energies, vary by about 30% to 60%. This variation is mainly caused by two factors: differences in the fraction of energy deposited in the streamer head region, and differences in the maximal electric field at the streamer head. When accounting for both factors, our computed G-values are in good agreement with an analytic estimate proposed by Naidis (2012 Plasma Sources Sci. Technol. 21 042001). We also simulate negative streamers and find that their production of N(4S), O(3P) and NO is less energy efficient. The results suggest that energy efficiency can be increased by reducing Joule heating in the streamer channel and by increasing the maximal electric field at the streamer head, for example by using short voltage pulses with a high applied voltage.

Unveiling the analogies between the atomic switch and NMDA receptor-based signal transmission of biological synapse

For the successful implication of brain-inspired computing using neuromorphic hardware, it is important to understand the detailed mechanisms of the biological brain. Here, we compare the atomic switch device with the N-methyl-D-aspartate receptor-based (NMDAR) signaling pathway which is the key to cognition in the human brain. An Ag/Ag2S/Pt gapless-type atomic switch configuration is realized using an atomic force microscope. The current responses to single and multiple voltage pulses of varied amplitude, width, and interval are studied to identify and control the conductance levels. This enables us to distinguish the sensory, short-term, and long-term memories along with the passive forgetting behavior and multilevel memory storage properties. Drawing a one-to-one comparison of these aspects of the atomic switch with the learning in the NMDAR pathway, we argue that the atomic switch has the potential not only as an edge-intelligent device but also as the missing link between biology and technology.

Partial Discharge Inception Characteristics of Twisted Pairs Under Single Voltage Pulses Generated by Silicon-Carbide Devices

Partial discharge (PD) is a major cause of degradation of motor winding insulation. It is a challenge to the successful electrification of all types of ground, sea, and aerial vehicles. However, the mechanism of PD under pulsewidth modulated voltages is not fully understood. This article studies PD inception characteristics in twisted pairs under single voltage pulses with reduced voltage overshoot, aiming to study the PD inception characteristics and mechanism without the influences of memory effects and voltage overshoot. The tests are conducted with a lab-designed 10-kV silicon carbide (SiC) device-based voltage pulse generator. The generator can produce voltage pulses with variable rise/fall times and pulse widths to emulate the output voltages of both silicon (Si) and SiC device-based power electronics converters. The voltage overshoot in this study has been limited to less than 5%. In addition, single voltage pulses are utilized as the excitation to remove charge memory effects. PD inception voltages, PD current magnitudes, and PD time delays of twisted pair samples are measured under various test conditions. It is found that the partial discharge inception voltage (PDIV) of the test sample decreases with reduced voltage rise time and increased voltage pulsewidth. Based on the test results, the impacts of voltage rise/fall times and pulse widths on PD behavior are explained using the extended volume-time theory. The relationships between PDIV, voltage rise/fall time, and pulsewidth are presented through empirical equations. Test results and analysis provide insights on the impacts of emerging wide bandgap devices in applications on motor winding insulations.

Spatio-temporal evolution of ion current extracted from pulsed dielectric barrier discharge

In the present study, the influence of various factors on the shape of the ion cloud extracted from the specific discharge setup was investigated. The overall installment presented a surface dielectric barrier discharge plasma in the air fed by impulse high voltage. The effect of the amplitude, polarity, and duration for single and repetitive voltage pulses were examined. The patterns of ion current distribution depending on the gas gap length and the average field strength were obtained, and the effect of pulse duration and frequency on the amount of the extracted charge were examined. It was shown that the extracted charge was non-uniformly distributed in the gap volume during single and periodic voltage pulses. The effect of volume charge accumulation in the gap at high pulse repetition rate was shown. Computer simulations demonstrated that the main role in the ion cloud shape distortion was caused by the surface charge deposited on the dielectric barrier.

Simulation results of the gas rarefaction and target ion evolution in a chopped high power impulse magnetron sputtering discharge

The high power impulse magnetron sputtering (HiPIMS) technique has recently been improved experimentally to deposit titanium films with several short micro-pulses that are decomposed from one single pulse. The additional control parameters cause a totally different current characteristic and result in a high deposition rate in these so-called chopped-HiPIMS (c-HiPIMS) sequences. Owing to the difficulty in digging deeply into the details of parameter variations through the experimental method, simulation works are adopted to exploit the complex mechanism. Here, the ionization region model is used to simulate the short micro-pulse discharge in HiPIMS. It is found that short pulse on-time tμon, long pause off-time tμoff, and the large number of micro-pulses within a single voltage pulse are factors that result in a higher deposition rate and are relevant to the gas rarefaction and the metal ion running away behavior.

Nanosecond dielectric barrier discharge on a curved surface in atmospheric air: streamer evolution and aerodynamic perturbations

A curved nanosecond-pulsed dielectric barrier discharge actuator is proposed to fit the flexibly complex surface shape of air vehicles. Streamer evolution and aerodynamic perturbations driven by a single-pulse voltage applied on the anode, where the pulse width is 35 ns and the peak voltage is 14 kV, are numerically studied. Continuity equations that consider 15 species and 34 reactions are solved based on the drift–diffusion approximation. The electron temperature is obtained using the local mean energy approximation method. Discharge characteristics during the voltage-rise, plateau and decay stages are discussed, respectively. The streamer is initiated at 2.2 ns. The maximum electric field is progressively located at the head of the streamer, between the electrodes and in the dielectric layer during the three voltage stages, while the maximum value of electron density is settled at the downstream tip of the driven anode. The electron number density at the streamer head increases at the voltage-rise stage, keeps constant during the voltage-plateau stage, decreases at the beginning of the voltage-decay stage and then increases due to the quenching effect of the excited species. Compared with the discharge on a flat surface, the initial discharge propagation velocity is smaller, while it decreases more slowly during the entire applied voltage. The simulated deposited energy matches the analytical solution well. Aerodynamic perturbations are investigated by solving the compressible Navier–Stokes equations. The ambient air is rapidly heated to the maximum temperature of 1883 K within 0.04 μs. The temperature rise remains greater than 1000 K for 0.32 μs and greater than 500 K for 21.6 μs. A ‘semiring-like’ compression wave is formed from the discharge region; the propagation speed decreases as it propagates away from the wall and then converges to 345 m s−1 at 13 μs. High-speed flows are rapidly induced at the beginning, and two vortexes are formed successively due to the interaction between the flow induced by the actuator and the backflow induced by the compression wave.

Discharge characteristics and reactive species production of unipolar and bipolar nanosecond pulsed gas–liquid discharge generated in atmospheric N2

In this paper, unipolar pulse (including positive pulse and negative pulse) and bipolar pulse voltage are employed to generate diffuse gas–liquid discharge in atmospheric N2 with a trumpet-shaped quartz tube. The current–voltage waveforms, optical emission spectra of excited state active species, FTIR spectra of exhaust gas components, plasma gas temperature, and aqueous H2O2, and production are compared in three pulse modes, meanwhile, the effects of pulse peak voltage and gas flow rate on the production of reactive species are studied. The results show that two obvious discharges occur in each voltage pulse in unipolar pulse driven discharge, differently, in bipolar pulse driven discharge, only one main discharge appears in a single voltage pulse time. The intensities of active species (OH(A), and O(3p)) in all three pulsed discharge increase with the rise of pulse peak voltage and have the highest value at 200 ml min−1 of gas flow rate. The absorbance intensities of NO2 and N2O increase with the increase of pulse peak voltage and decrease with the increase of gas flow rate. Under the same discharge conditions, the bipolar pulse driven discharge shows lower breakdown voltage, and higher intensities of excited species (N2(C), OH(A), and O(3p)), nitrogen oxides (NO2, NO, and N2O), and higher production of aqueous H2O2, and compared with both unipolar positive and negative discharges.

Reset Variability in Phase Change Memory for Hardware Security Applications

The rapid quench from melt associated with the reset operation in phase change memory is a suitable physical process to leverage programming variability for hardware security. We have experimentally characterized cell-to-cell programming variability in Ge2Sb2Te5 (GST) line cells using a single reset voltage pulse with moderate amplitude. We have observed that the cell dimensions and programming pulse parameters play a critical role on the programming variability. Cells with larger length-to-width ratios ( L/W ≥ 1.8) show greater programming variability when moderate reset voltage amplitudes ( Vappl ) are applied. This variability is further increased with shorter pulse edges ( tedge ) of the applied pulses. We have performed a study for a reset-variability-based physical unclonable function (PUF) with 85 cells (with L/W = 4) by applying identical single pulses with shorter tedge and a pre-calibrated Vappl . Cells are randomly programmed to the full reset (high-resistance-state or HRS), or the partial reset or set (low-resistance-state or LRS) states with an equal probability and the two states are separated by ∼1.5 order of magnitude. No bit flipping is observed after 9 months of programming and instead, the separation increases to ∼3 orders of magnitude because of the upward and downward resistance drift of the HRS and LRS states. The underlying physical mechanisms behind the enhanced variability are identified as thermal runaway at the onset of GST melting and the additional current overshoot due to the parasitic capacitances, based on the results obtained from COMSOL finite element simulations and SPICE circuit modeling of the experimental setup.

Dose effect of gamma radiation on reliable voltage pulse measurement in nuclear fusion experiments

The effect of gamma radiation on the reliable measurement of single voltage pulses of electron beam injectors into plasma during fusion experiments is considered in the manuscript. For this purpose, a 10 GHz fast voltage divider was constructed. The high-voltage capacitor was a gas condenser, and the low-voltage capacitor was a parallel connection of 10 mica capacitors. It turned out that the received radiation dose corrects the transmission ratio since it aligns the frequency characteristic of the mica in the area of spatial charge. This phenomenon has been explained from both a positive and a negative aspect with an effect on the concrete application. The need for further research on this problem was also pointed out to establish a saturation dose and thus obtain a constant frequency characteristic of the mica. The interest in the fast-divider behavior in the neutron field is also highlighted.

Coplanar Electrowetting-Induced Droplet Detachment from Radially Symmetric Electrodes.

This work demonstrates electrowetting-induced droplet detachment in air from coplanar electrodes using a single voltage pulse. It also presents two models to predict when this detachment will occur. Previous works approximated the minimum energy for detachment based on (i) adhesion work at the solid-liquid interface and (ii) interfacial energy changes along all three interfaces in the system. This investigation updates those models to include changes in gravitational potential energy during detachment and provides validation by testing predicted detachment thresholds against experimental observations. Droplets of varying volume were ejected from electrowetting devices with (i) radially symmetric four-part coplanar electrodes and (ii) single electrodes with a ground wire inserted directly into the droplet. All experiments were performed in air. Incorporation of gravitational potential energy improves predictions for critical electrowetting number and captures the observed increase in applied voltage required with increased droplet volume. These new models will be of particular benefit in three-dimensional digital microfluidics applications that manipulate droplets in air.

Complex dynamics of a non-volatile memcapacitor-aided hyperchaotic oscillator

To explore memcapacitors and their characteristics in chaotic oscillators, this paper proposes a logarithmic charge-controlled memcapacitor model. Using power-off plot analysis, we show that the memcapacitor possesses continuous non-volatile characteristic. Also, its dynamic route map shows the memcapacitor can rapidly switch from one memcapacitance to another by applying a single voltage pulse. Based on the memcapacitor model, we design a chaotic oscillator, which can exhibit some complex dynamic characteristics, such as chaos, hyperchaos and various coexisting attractors. The multistable coexisting oscillation of the system is further analyzed by using phase portraits, basins of attraction and double-bifurcation diagrams. Symmetric coexistence attractors with infinite homogeneity and heterogeneity are also found, which can evolve into hyperchaos under certain initial conditions. Finally, the chaotic oscillator is verified by numerical simulations and digital signal processor experiments.

Discharge Development in a Saline Solution at the Above-The-Threshold Voltages

The process of a breakdown in a saline solution in a pin – plane electrode geometry is investigated for the interelectrode gap of 1 cm and a 3% NaCl concentration in the water. Single voltage pulses of about 2 ms duration and amplitude of a few kilovolts are applied to the gap. A current of up to units of kiloamps is passed through the gap. It is shown that a necessary condition for the discharge to form is the availability of gaseous cavities in the electrolyte. The stages of discharge development are investigated at the voltages applied to the gap, which exceed the threshold value (at which plasma forms in the gas cavities). An analysis of the influence of the processes of formation and collapse of gas cavities in the solution and plasma in the cavities on the shape and value of the discharge current is performed.

Effect of Operating Mode of the Input-Output Ports of Complex Functional Devices on Indicators of the Pulsed Electric Strength of the Product

We test the durability of the simplest AVR ATtiny13A microcontroller (from Atmel) to the effects of single voltage pulses depending on the input-output port configuration. The dependence of the impulse electric strength of the microcontroller on the operation mode of the ports is discovered.

Broadband nonlinear modeling of RF amplifier-driven systems for multiharmonic predistortion of pulsed output signals

By applying pulsed voltages to particle beams in circular accelerators, the longitudinal distribution of the particles can be controlled. Specifically, so-called barrier bucket systems can be used to enclose the beam between two barrier pulses. The challenge in these barrier bucket systems is, that the high voltage pulses need to be of a certain shape with high signal quality in order to preserve a high beam quality. In order to generate the pulses, frequencies up to 100 times the fundamental frequency are required, leading to high signal distortion caused by frequency-dependent properties of the system and nonlinearities of the power amplifier at high output power. In order to reach the required well-defined output pulses, signal predistortion is indispensable.However, nonlinear PA modeling and signal predistortion tends to focus on modulated signals rather than pulsed voltages as it is mainly used in communication technology. Thus, many previously developed predistortion methods are not applicable for our application or have to be adapted for single voltage pulses. Here, we first define a distortion rate as a quantity for the deviation between the produced signal and the ideal output. In a second step, a Hammerstein model is developed for modeling both, the PA and the driven system together, and finally, the model is tested for two different PAs.