Types Of Pulse Generators Research Articles

Influence of Trigger Injection on Performances of a Single-Gap Pseudospark Switch

Trigger injection and its influence on performances of a single-gap pseudospark switch were studied by using a high-dielectric trigger unit and two types of pulse generators, where pulse parameters, polarity effect, anode voltage, and electrode geometries were varied. It is found that pulses with the rising edge of nanosecond scale can cause diffused electron emission in a large region of the trigger unit, while the slower pulses result in a localized surface flashover. The trigger injection is strongly polarity-dependent, and the way of applying the negative pulse voltage to the outer electrode is more favorable. Not all injected electrons can contribute to the triggering process, and the only factors that can lead to higher charge quantity and energetic components of electrons with a short injection delay are helpful to reduce the trigger delay. A model considering the potential penetration is presented to explain the influence of trigger injection, anode voltage, and electrode geometries. When trigger injection is strong enough or the ratio of cathode hole diameter to its thickness is relatively large, the trigger delay remains constant at different anode voltage; otherwise, it decreases as the anode voltage increases.

Analysis of mechanism based on two types of pulse generators in micro-EDM using single pulse discharge

Micro-electrical discharge machining (micro-EDM) has become an advanced machining technique in recent times. In the micro-EDM process, the power supply unit (PSU) is an important component because of its considerable influence on the machining parameters. Additionally, there are two main types of pulse generators: RC- and transistor-type pulse generators. In this study, a series of novel analyses and experiments featuring the mechanisms of each of the two types of pulse generators were conducted using single discharge pulse. The discharge characteristics of the two types of generators were discussed first. Then, the differences in their discharge channel radii when using the plasma model with single pulse were presented. In addition, their thermal effects were analyzed using the thermal heat model with single pulse. Lastly, a train of related single pulse discharge experiments was carried out using the two different pulse generators with varied simulation parameters in order to observe real phenomena in micro-EDM. The results of experiments were consistent with those of simulations, and the two different pulse generators can be applied to different situations, depending on the machining circumstances, as a result of their different machining characteristics. The findings of this study are expected to help guide the selection of the pulse generator type based on parameter requirements in micro-EDM.

Spinal Cord Stimulation

Spinal Cord Stimulation

Mid-frequency deposition of a-C:H films using five different precursors

The plasma-enhanced chemical vapour deposition (PECVD) of amorphous hydrogenated carbon films from pulsed discharges with frequencies in the range from 50 kHz to 250 kHz was investigated. Five different hydrocarbons (acetylene C 2H 2, isobutene C 4H 8, cyclopentene C 5H 8, toluene C 7H 8 and cycloheptatriene C 7H 8) were probed as film growth precursors. In addition, two types of pulse-generators with somewhat different waveforms were used to power the discharges in the so called mid-frequency range. The a-C:H films deposited in a parallel-plate reactor were characterised for their thickness/deposition rate, hardness and hydrogen content. The hydrogen concentration in the films varied between 19 at.-% and 37 at.-%. With the substrate temperature held constant, it is roughly in inverse proportion to the hardness. The film with the highest hardness of 25 GPa was formed at a deposition rate of 0.8 μm/h in the C 2H 2 discharge at the lowest investigated pressure of 2 Pa. With increasing molecular mass of the precursor mostly weaker films were deposited. Relatively high values of both deposition rate and hardness were achieved using the precursor isobutene: a hardness of 21 GPa combined with a deposition rate of 4.1 μm/h. From the probed precursors, isobutene is also most advantageous for a-C:H deposition at higher pressures (up to 50 Pa investigated). But, as an over-all trend, the a-C:H hardness decreases with increasing deposition rate.

Development and prospects of mineral liberation by electrical pulses

The sequences of development of the contemporary mineral liberation technique are reviewed, and the emergence and development of contemporary mills as a main mineral liberation tool, is discussed. The origin of development of the technique and the working hypothesis of the mechanism of high voltage electrical pulse liberation of minerals are described, and the state of the contemporary design and construction of pulse generators are discussed. The types of pulse generators and working chambers, used in the reported liberation tests, are presented. The technological results of tests on the liberation of diamonds, emeralds, minerals, containing metals of platinum group, refractory gold and silver, iron, copper, magnesium ilmenite, and of metals of smelter slags, are reported. The account of the application of pulse liberation technique for the recovery of gold from old tailings by application of high frequency and low energy pulses, is given. The prospects and ways of introduction of the technology of mineral liberation by pulses into industry are discussed.

Mid-frequency deposition of a-C:H films using five different precursors

The plasma-enhanced chemical vapour deposition (PECVD) of amorphous hydrogenated carbon films from pulsed discharges with frequencies in the range from 50 kHz to 250 kHz was investigated. Five different hydrocarbons (acetylene C 2H 2, isobutene C 4H 8, cyclopentene C 5H 8, toluene C 7H 8 and cycloheptatriene C 7H 8) were probed as film growth precursors. In addition, two types of pulse-generators with somewhat different waveforms were used to power the discharges in the so called mid-frequency range. The a-C:H films deposited in a parallel-plate reactor were characterised for their thickness/deposition rate, hardness and hydrogen content. The hydrogen concentration in the films varied between 19 at.-% and 37 at.-%. With the substrate temperature held constant, it is roughly in inverse proportion to the hardness. The film with the highest hardness of 25 GPa was formed at a deposition rate of 0.8 μm/h in the C 2H 2 discharge at the lowest investigated pressure of 2 Pa. With increasing molecular mass of the precursor mostly weaker films were deposited. Relatively high values of both deposition rate and hardness were achieved using the precursor isobutene: a hardness of 21 GPa combined with a deposition rate of 4.1 μm/h. From the probed precursors, isobutene is also most advantageous for a-C:H deposition at higher pressures (up to 50 Pa investigated). But, as an over-all trend, the a-C:H hardness decreases with increasing deposition rate.

Modernization of testing equipment for inspection of damage in gas pipelines’ insulation

Two types of pulse generators are developed that, being supplied from the same automobile battery (12 V), produce an output power of 100 W at a frequency of 1 kHz with ∼80% efficiency. These generators are included in the testing equipment for inspection of damage in gas-pipeline insulation and are used in the Ural region, in particular, in Pervoural’sk, Novoural’sk, Mednogorsk, Izhevsk, Khanty-Mansiisk, Buzuluk, and Tobol’sk.