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The plasma produced by a pulsed generator is an efficient tool for an airflow control. In this paper, a nanosecond pulsed generator constructed with a fast solid-state switch is designed for triggering synchronous discharges in plasma synthetic jet (PSJ) actuators connected in series. The generator delivers high-voltage pulses with a peak voltage varying from 0 to 20 kV, a rise time of 20 ns, a full-width at half-maximum of 200 ns, and a wide range of pulse-repetition rate varying from 0 to 5.5 kHz. It is proved that this generator is able to trigger synchronous discharges in three PSJ actuators in atmospheric air with a peak discharge current more than 90 A and a deposited energy per pulse of 39 mJ. A schlieren system is used to observe the airflow dynamics, which shows the high synchronization among the three PSJ actuators with a time triggering delay of about 20 ns. The synchronous operation of three PSJ actuators produces a plasma jet with a maximum velocity of 60 m/s and a precursor wave with a velocity of 350 m/s. [ABSTRACT FROM AUTHOR]

This paper presents an electromagnetic simulation method for spark-gap switched pulse generators (SGSPGs). Electromagnetic simulation programs can be useful for designing nanosecond or subnanosecond SGSPGs; however, these programs do not support simulation models of spark-gap switches. This paper describes a simulation method that determines electric field at an observation point in the SGSPG by replacing the spark-gap switch with a step voltage source. In this simulation, the discharge properties of the spark-gap switches, including the breakdown voltage and rise time, are determined using the results of the studies on electrical breakdown. A 1-ns single pulse-forming line was fabricated to validate the proposed method. The simulated waveform was in good agreement with the measured waveform. [ABSTRACT FROM PUBLISHER]

The trigger voltage is usually high in traditional three-electrode gas switch, which makes the trigger system large and complex in large-scale pulsed power system such as linear transformer driver. In this paper, a three-electrode gas switch triggered by microhollow cathode (MHC) discharge is put forward, which can be operated stably under low trigger voltage. MHC discharge is a kind of microplasma with the characteristics of low trigger voltage (several thousand volts), high electron density, and high gas pressure discharge. In this switch, three MHC triggers sharing the same cathode are designed as the third electrode of the switch in the middle. Positive and negative high voltages are applied to two main electrodes, respectively. The breakdown characteristics of MHC discharge triggered by pulse voltage are first studied. The trigger voltage can be as low as 8 kV at 0.3 MPa in pure N2 with the discharge peak current up to 80 A. A circuit simulation model describing breakdown process of MHC is also built. Then two operating modes of the switch, three-electrode mode (T-mode) and two-electrode mode (D-mode), are analyzed. The stable operation with the charging voltage from ±35 to ±50 kV is realized under different working coefficients from 64% to 92% and different trigger voltages from 8 to 15 kV. The turn-on parameters including delay time, jitter, and turn-on time are studied that the delay time and jitter of D-mode are longer than that of T-mode under the same condition. At last, the improvement of MHC trigger for the stable operation of D-mode with shorter delay time is described. [ABSTRACT FROM PUBLISHER]

In this paper, a dual-electrode gas switch triggered by ejected plasma is proposed to ensure the switch to be triggered reliably under extremely low switching coefficient. The switch has the configuration of dual electrodes, in one of which a microincentive chamber is embedded to develop ejected plasma into the switch gap, leading to the breakdown of the switch. Both the features of ejected plasma and the triggering discharge characteristics of the switch are studied with different types of gas, gas pressures, voltage polarities, gap distances, triggering pulse energies, and so on. The results show that the switch can be triggered reliably in a much wide working voltage range, as the minimum switching coefficient is low to 9% with the delay time of about 10 \mu \texts . With the decrease of gas pressure and the increase of triggering pulse energy, the height of ejected plasma increases while the delay time of the switch reduces. The polarities of charging voltage and triggering voltage both have obvious influence on the delay time of the switch, and the effect of the former is greater. Under the same gas pressure and triggering pulse energy, the delay time in SF6 is much bigger than that in N2. [ABSTRACT FROM PUBLISHER]

To study the lighting shielding of ultrahigh voltage (UHV) transmission lines across mountains and the hillside effects on discharge process, experiments have been carried out with a reduced scale tower model. As the spatial electric field is changed by the slope, the space of shielding failure is enlarged. When the high-voltage electrode is 5 m to the transmission line, the vertical length of shielding failure is 8 m for the 30° slope, which is larger than 5.17 m for the flat ground. The maximum probabilities of striking the lines are 95% for the slope and 75% for the flat ground. When the vertical distance from the high-voltage electrode to the hillside is less than that to the transmission lines, the probabilities of discharge striking the flat ground are 85% for the 5-m gap and 94% for the slope for the same gap. When the vertical distance from the high-voltage electrode to the hillside is equal to that to the flat area, the hillside does not affect the average discharge voltage apparently but discharge time and discharge dispersity. The results of this paper are valuable for lighting protection of UHV transmission lines in mountainous areas. [ABSTRACT FROM PUBLISHER]

A pseudospark switch with two hollow electrodes separated by a ceramic disc in between with a trigger plug inserted near the hole has been fabricated, and it was successfully operated. In this paper, a 29-kV anode voltage, 3.6 kA at 2.2 kHz with 11-ns rise time, has been achieved and operated, successfully. A simple trigger pulse has also been designed, built, and operated effectively reaching more than 1.6-kV trigger voltage that was sufficient to ignite the gas inside the cathode. The main plasma discharge produces 1-ns jitter time that occurred in a reliable manner for more than 6 h of operation continuously. [ABSTRACT FROM PUBLISHER]

Field distortion gas switches are extensively used in pulsed power systems. Switch performance typically degrades because of electrode erosion, which directly influences the output parameters, stability, and reliability of pulsed power systems. With the same value of $pd$ , different pressure and gap lengths in gas switches can affect electrode erosion property and thus, the subsequent performance degradation, but few results have been published. In this paper, repetitive discharges have been undertaken in a three-electrode field distortion gas switch with fixed pd$ to study the influence of pressure and gap length on electrode erosion and switch performance. The morphology of electrode surface and time histories of both trigger jitter and the probability of prefire have been investigated during the whole life cycle of the gas switch. The results show that when pd$ is fixed, high pressure and a short gap make for low trigger jitter at the start of the switch life cycle but lead to more severe electrode erosion, expediting the degradation of performance in field-distortion gas switches. Meanwhile, the probability of prefire increases rapidly with the increase of pressure. [ABSTRACT FROM PUBLISHER]

In this paper, we investigated a water treatment method that sprays waste water droplets into a pulsed discharge space. To increase energy efficiency of this method, a pulsed power generator should output a pulsed power of a high peak and a short pulse width and be low circuit loss, high repetition rate, high power, and high stability. An inductive energy storage circuit using a semiconductor opening switch was studied to satisfy the above-mentioned requirement. Initially, effect of turn ratio of a pulse transformer (PT) in the circuit was investigated. Energy transfer efficiency and the pulsewidth of the output voltage increased with the PT turn ratio, resulting in an increase of the efficiency of the water treatment system. Then, the effect of the load impedance was investigated. The result showed that an optimum resistance to maximize the efficiency exists. From these results and a previous experimental report, we concluded that the optimization conditions are summarized below. The turn ratio and the inductance in the secondary circuit should be as high as possible under the condition, which does not output the very long pulse. The impedance of the discharge at an electrode for the water treatment should be a value that maximizes the energy transfer efficiency. Capacitance of capacitors in the circuit should be adjusted to obtain optimal peak voltage for the generation of active species. [ABSTRACT FROM PUBLISHER]

Reducing the working coefficient of gas switch can effectively lower the prefires probability. This paper discusses in detail the discharge characteristics of a three-electrode plasma-jet triggered gas switch (PJTGS), especially at low working coefficients. The triggered discharge process of the PJTGS is analyzed. Plasma jets are observed and discussed with respect to trigger voltage, trigger energy, and gas pressure. In addition, the switch jitters at different conditions are investigated, including ground resistor, charging voltage, trigger energy, trigger voltage, and working coefficient. The results indicate that the height of the plasma jet increases with the increase of trigger voltage and energy, and decreases with the increase of gas pressure. At working coefficients higher than 75%, trigger voltage of +80 kV, and ground resistor of 100 \(\Omega \) , reliable subnanosecond jitters can be obtained with the charging voltages of ±25, ±30, ±40, and ±50 kV. When the working coefficients are between 50% and 28.1%, the switch jitters range from 1.6 to 3.5 ns. Even at the working coefficient of 28.1%, the PJTGS can still be triggered reliably with a switch jitter of 3.5 ns. [ABSTRACT FROM AUTHOR]

In this paper, a novel six-channels annular plasma-jet chamber is designed and embedded in the trigger electrode of the three-electrode gas switch to generate multichannel plasma jets without air flow, which is used to trigger the gas switch to form multichannel discharge. Results of this paper show that the plasma-jet triggering can be conductive to steady formation of multichannel discharge. [ABSTRACT FROM PUBLISHER]