Effect Of Pulse Interval Research Articles

Effect of pulse interval on deposition of diamond-like carbon through high-power impulse magnetron sputtering

A diamond-like carbon (DLC) film was deposited using unipolar-double-pulse high-power pulsed magnetron sputtering, aimed at enhancing both film density and deposition rate. The pulse interval between the 1st and 2nd pulses, with negative polarity applied to the target, was varied from 15 to 200 μs. Temporal variations in the flux and energy of C+ and Ar+ incident to the DLC film were analyzed through energy-resolved and time-resolved mass spectrometry to clarify the ion generation process during the 1st and 2nd pulses. The contribution of ionic species in forming the DLC film through HiPIMS was clarified through mass spectrometry, Raman scattering spectroscopy, and X-ray reflectivity analyses. Reducing the pulse interval increased the deposition rate, and the film density of the DLC film was improved at a pulse interval of approximately 40 μs. Overall, the implementation of a double pulse with the appropriate pulse interval can help enhance both the film density and deposition rate.

Effects of Pulse Interval on Forming Process in Wire Arc Metal Additive Manufacturing Using Pulsed Arc Plasma.

To overcome the material processing challenges induced by high levels of heat input in wire arc additive manufacturing (WAAM), an innovative WAAM method using pulsed arc plasma (PAP-WAAM), was developed by the authors in the previous study. In this method, the PAP generated by the pulsed voltage was used as the heat source. The pulse interval can be defined as the time interval between adjacent pulse voltages, which determines the ignition time and frequency of the arc plasma, thus influencing the forming process. However, the effect of pulse interval on the forming process has not yet been revealed. Here, the effects of pulse interval on forming process during the PAP-WAAM of Ti6Al4V, including thermal behavior, arc plasma characteristics, and metal transfer process, were investigated by experiments and simulation. The results exhibited that the interpass temperature and maximum peak temperature decrease with increasing pulse interval at the same arc plasma power, indicating an alleviation of heat accumulation along the building direction. As the pulse interval increased, the ignition mode of the arc plasma changed from ignition between the tungsten electrode and the previously deposited layer to ignition between the tungsten electrode and filler wire, which increased the proportion of discharge energy allocated to the filler wire, thus reducing the overall heat input required for material deposition. When the pulse interval was 300 and 400 ms, only the uninterrupted bridging transfer mode was observed during the deposition process. The uninterrupted bridging transfer is considered to contribute to forming a smooth and consistent layer appearance. In addition, longer pulse intervals resulted in less surface oxidation, narrower wall thickness, and better macrostructure, attributed to reduced heat input and improved effective heat dissipation. This research reveals the effect of pulse interval on forming process during PAP-WAAM, which benefits the fabrication of desirable metal parts.

Effect of Pulse Interval on Promoting Secretion of Neurite-Inducing Factor from Glioma Cells in the Application of Nanosecond High Electric Field Pulses

1. Purpose We previously discovered and reported that the application of nanosecond high electric field pulses transiently increased intracellular Ca2+ concentration in glioma cells to promote the secretion of neurite-inducing factor. Moreover, it has been clarified that the electric field strength, the number of pulse application, and the pulse width have a strong effect on the secretory ability as a condition for promoting the secretion of these neurite-inducing factors. In this presentation, we further report that even nanosecond pulses with a weak electric field strength which does not cause the increase of intracellular Ca2+ concentration with a single pulse can induce the intracellular Ca2+ increase and neurite-inducing factor secretion from glioma cells by applying multiple pulses with short intervals. The considered mechanism also will be discussed in this presentation. さらに表示 2. Experimental method Rat glioma C6 cells were seeded on an ITO electrode and cultured overnight to adhere. To monitor intracellular Ca2+ concentration the cells were treated with a medium containing Fura-2 AM for 30 minutes to introduce the Ca2+ indicator into the cells. After washing the cells on the electrode, Hanks Balanced Salt Solution (HBSS) was put in the chamber, and an aluminum plate electrode serving as a counter electrode was faced to ITO electrode with a spacer in thickness of 30 µm, and set on the stage of an inverted fluorescence microscope. After two minutes from the start of measurement, nanosecond electric field pulse was applied in various voltage and pulse interval, and changes in intracellular Ca2+ concentration were observed. Furthermore, thapsigargin and 2-aminoethoxydiphenylborane (2-APB) were used to confirm that the increase in intracellular Ca2+ concentration may be due to Ca2+ release from the endoplasmic reticulum via IP3 receptors. In addition, after applying a nanosecond high electric field pulse to C6 cells in the same manner in a clean bench, the HBSS was immediately replaced with DMEM medium containing 10% FBS, and the cells were cultured for 1 day or 2 days. The culture supernatant (Conditioned Medium: CM) of the C6 cells was then collected, and exchanged completely with the medium of PC12 cells, which is a neural progenitor cell model. The morphological change of PC12 cells was observed and recorded for 6 days. The PC12 cells which extended the neurites more than twice as the cell body were recognized as neuronal differentiated cells. By calculating the differentiation rate of PC12 cells, it was evaluated how the secretion of the neurite-inducing factor from C6 cells was promoted or not. 3. Results and discussion Three pulses with a pulse width of 140 ns and an electric field strength of 23 kV / cm were applied at intervals of 2 seconds, 30 seconds, and 1 minute to C6 cells and intracellular Ca2+ concentration changes and neurite-inducing factor secretion was examined. It was demonstrated that intracellular Ca2+ gradually increased at shorter intervals of 2 seconds and 30 seconds, but not increased at intervals of 1 minute. In addition, intracellular Ca2+ concentration increase was observed even when pulse application was done in the absence of extracellular Ca2+. It indicated that this increase in intracellular Ca2+ concentration is due to Ca2+ release from organelles. Furthermore, intracellular Ca2+ concentration elevation was not induced by the same pulse application after treatment with thapsigargin or 2-APB. Therefore, it was considered that Ca2+ was released from the endoplasmic reticulum via IP3 receptors by the pulse application in this condition. Figure 1 (a) and (b) show images of PC12 cells cultivated in the CM of C6 cells which were exposed to three pulses with 1 minute or 2 seconds intervals, respectively. From these results, it was demonstrated that the secretion of the neurite-inducing factor was promoted by the multi-pulse application with short intervals. Furthermore, it was found that the Ca2 + release via IP3 receptors of the endoplasmic reticulum and following promotion of the secretion of neurite-inducing factor could be induced by shortening the nanosecond multi-pulse interval in the application of weak electric field. Now, we are planning to clarify what kind of gene expression in C6 cells is induced by pulse application to identify and quantify the secreted neurite-inducing factor. Figure 1

Study on Discharge Parameters of Surface Strengthening with Powder Mixed Near Dry EDM for H13 Steel

Surface strengthening for H13 steel with powder mixed near dry EDM, research the effect of different discharge parameters on the microstructure and hardness of strengthened layer .The results show that the effect of pulse interval on microstructure and micro hardness is not obvious, the influence of the pulse width less than the peak current. As the increasing of peak current, strengthening layer surface quality get better, when the peak current reach to 14A , preferable microstructure of strengthening layer can be obtained.

Monitoring and control of the micro wire-EDM process

A new pulse discriminating and control system has been developed for process monitoring and control in micro wire-EDM. The pulse discriminating and control system identifies four major gap states classified as open circuit, normal spark, arc discharge and short circuit based on the characteristics of gap voltage waveform. The effect of pulse interval, machining feedrate and workpiece thickness on the variations of the proportion of normal spark, arc discharge and short circuit in the total sparks (defined as normal ratio, arc ratio and short ratio, respectively) were investigated. It is found that a long pulse interval results in an increase of the short ratio under a constant feedrate machining condition. A high machining feedrate or an increase of workpiece height results in an increase of the short ratio. To achieve the stability of the machining operation, a control strategy is proposed by regulating the pulse interval of each spark in real-time according to the identified gap states. Experimental results indicate that the developed pulse discriminating and control system can significantly reduce the arc discharge and short sparking frequency as well as achieve stable machining under the condition where the instability of machining operation is prone to occur.