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The reduction of local heat load on the structural elements of aircraft or spacecraft vehicles due to the shock wave/boundary layer interaction can be successfully controlled in the future using a system of plasma actuators. The efficiency of plasma aerodynamic actuators operation is directly related to a power source. It determines a covered plasma area, an air flow speed and a thrust the actuator creates. The paper deals with the operation of a high-voltage source of sawtooth pulses with high efficiency for controlling plasma actuators. The pulse power source can be easily scaled for different nonlinear capacitive loads. • Sawtooth pulse source with high efficiency was created to power plasma actuators. • The source has simple structure, flexible in control and reliable in operation. • The power source operation was successfully tested. • The stable source operation was obtained as at idle mode as on the plasma actuator. [ABSTRACT FROM AUTHOR]

High‐voltage (HV) pulses are widely used in many applications. This study proposes a new HV unipolar pulse generator based on Single‐Ended Primary‐Inductance Converter (SEPIC) for electroporation applications. The converter in the proposed pulse generator operates in discontinuous conduction mode with continuous input current. The proposed structure uses voltage‐boosting modules that are fed from a relatively low voltage DC source with a reduced number of semiconductors. The number of semiconductor devices and the voltage stress across them are important issues for HV pulse generators. The proposed approach does not have any chopping switches at the output stage, which greatly affects cost, efficiency, and system control. The employed semiconductor switches and diodes in the proposed topology have low voltage and current stresses, so the structure can be implemented with the market‐available semiconductor technology. Mathematical analysis is presented along with a full design of the system components. Finally, simulation and experimental results are presented to validate the proposed concept. [ABSTRACT FROM AUTHOR]

A new concept of effective high-voltage nanosecond pulse generators based on two compression cascades of drift step recovery diodes (DSRDs) is presented. The main advantage of the proposed approach arises from the decoupling of the operation cycles of DSRD cascades while using a single primary switch. This greatly improves the overall efficiency of the system. The first DSRD cascade operates with low pulse current densities. Its operation cycles can be extended resulting in an increase of the compression factor and pulse energy, whereas the loss level is kept at a minimum. The second DSRD cascade operates with high current densities, but the duration of its cycles can be chosen much shorter which ensures good efficiency too. Furthermore, an extension of the working cycle of the first DSRD cascade makes the requirement for the primary switch milder so that even relatively slow low-voltage switches can be employed. [Display omitted] • Drift step recovery diodes (DSRD) are effective for the HV nanosecond pulses forming. • The DSRD circuit operates as a pulse compression cascade. • Multi-cascade compression improves the total efficiency and the pulse parameters. • The optimal operation regimes for DSRD cascades differ significantly. • Using the single primary switch simplifies the circuit design. [ABSTRACT FROM AUTHOR]

The parameters of runaway electrons produced in nanosecond high-voltage discharges in different gases (air, nitrogen, sulphur hexafluoride, krypton, argon, methane, neon, hydrogen, helium) at atmospheric and higher pressure were studied. An optical analysis was also performed to investigate the ionisation dynamics in diffuse discharges in nitrogen and nitrogen-containing mixtures. At breakdown of a point-to-plane gap by nanosecond (≃2 ns) high-voltage (≃200 kV) pulses of negative voltage polarity and gas pressure above 0.1 MPa, a supershort avalanche electron beam (SAEB) was detected by a collector behind the flat anode. For pressure >0.1 MPa of nitrogen and other gases it is shown that the maximum pressure for SAEB registration decreases with increasing the voltage pulse rise time. Therefore, to detect a SAEB at atmospheric and higher gas pressure, one should use voltage pulses with an amplitude of hundred kilovolts and rise time of ∼1 ns and shorter. The experimental research in the dynamics of optical radiation from the discharge plasma shows that the breakdown in which runaway electrons are produced develops as an ionisation wave.

Purpose – The purpose of this paper is to study high-voltage interactions in polymer thick-film resistors, namely, polyvinyl chloride (PVC)-graphite thick-film resistors, and their applications in universal trimming of these resistors. Design/methodology/approach – The authors applied high voltages in the form of pulses and impulses of various pulse durations and with different amplitudes to polymer thick-film resistors and observed the variation of resistance of these resistors with high voltages. Findings – The paper finds that high voltages can be used for trimming of polymer thick-film resistors in both directions, i.e. upwards and downwards. Research limitations/implications – The research implication of this paper is that polymer thick-film resistors can be trimmed downwards or upwards practically using this method. Practical implications – The practical implications of this paper is that one can trim the polymer thick-film resistors, namely, PVC–graphite thick-film resistors, in both directions, i.e. upwards and downwards, by using this method. Originality/value – The value of the paper is in showing that high voltages can be used to trim downwards and also upwards in the case of polymer thick-film resistors. This type of trimming is called universal trimming, developed first time for polymer thick-film resistors. [ABSTRACT FROM AUTHOR]

This paper describes a modular solid-state switching cell derived from the Marx generator concept to be used in topologies for generating multilevel unipolar and bipolar high-voltage (HV) pulses into resistive loads. The switching modular cell comprises two ON/OFF semiconductors, a diode, and a capacitor. This cell can be stacked, being the capacitors charged in series and their voltages balanced in parallel. To balance each capacitor voltage without needing any parameter measurement, a vector decision diode algorithm is used in each cell to drive the two switches. Simulation and experimental results, for generating multilevel unipolar and bipolar HV pulses into resistive loads are presented. [ABSTRACT FROM PUBLISHER]

The recent progress in electrical comminution using high-voltage pulses and the technical challenges in order to bring this technology to the mining industry are outlined. Pre-weakening ore particles and preferential liberation of minerals at coarse sizes are the two major research outcomes that may have potential benefits for the industry. A particle pre-weakening characterization method by single-particle/single-pulse test has been developed. The emerging challenges for the mining industry to realize the benefits of this novel comminution technology include scale-up for industrial application, hybrid circuit design, maximization of pulse-induced cracks, and study of the downstream processing effects. [ABSTRACT FROM AUTHOR]

A method for measuring the energy absorbed under a nonlinear load that employs a reverse current shunt is described. The design features of the reverse current shunt and the peculiarities of its use to study high-voltage (10-100 kV) pulses with a nanosecond duration are considered. The experimental results of applying this method to the investigation of the energy absorption during high-voltage pulse gas discharge are presented. [ABSTRACT FROM AUTHOR]

The results of the measurement of the parameters of particle beams generated by a high-voltage nanosecond anode-initiated surface vacuum discharge are presented in this paper. Pulses with voltages of up to 120 kV with rise times of 20 ns are applied to coaxial and linear electrodes on polytetrafluoroethylene samples. The discharge current and the current of the ionic component of a particle beam are measured. In addition, the thrust pulse and the directional pattern of the beam are defined. It is shown that the directional pattern is narrower and the ionic current is higher when the coaxial electrode geometry is used instead of linear configuration, whereas the most probable speed of ions remains the same. [ABSTRACT FROM AUTHOR]

This paper includes the results of an investigation of high-voltage pulse effects on insulators of a 10-kV power line. Experiments have been performed by means of equipment that simulates the simultaneous effect of a pulse disturbance and a power line operating voltage. Critical levels of insulator flashover have been determined. These levels are dependent on the pulse disturbance duration, and a number of other effects. The electric characteristics of insulators degrade when high-voltage pulses are injected on an insulator with power ON. As a result, some insulators have been destroyed. The possible reason of destruction is the presence of latent defects. [ABSTRACT FROM AUTHOR]