Dynamics of bipolar HiPIMS discharges by plasma potential probe measurements

The plasma potential at a typical substrate position is studied during the positive pulse of a bipolar high-power impulse magnetron sputtering (bipolar HiPIMS) discharge with a Cu target. The goal of the study is to identify suitable conditions for achieving ion acceleration independent on substrate grounding. We find that the time-evolution of the plasma potential during the positive pulse can be separated into several distinct phases, which are highly dependent on the discharge conditions. This includes exploring the influence of the working gas pressure (0.3 – 2 Pa), HiPIMS peak current (10 – 70 A corresponding to 0.5 – 3.5 A/cm2), HiPIMS pulse length (5 – 60 μs) and the amplitude of the positive voltage U+ applied during the positive pulse (0 – 150 V). At low enough pressure, high enough HiPIMS peak current and long enough HiPIMS pulse length, the plasma potential at a typical substrate position is seen to be close to 0 V for a certain time interval (denoted phase B) during the positive pulse. At the same time, spatial mapping of the plasma potential inside the magnetic trap region revealed an elevated value of the plasma potential during phase B. These two plasma potential characteristics are identified as suitable for achieving ion acceleration in the target region. Moreover, by investigating the target current and ion saturation current at the chamber walls, we describe a simple theory linking the value of the plasma potential profile to the ratio of the available target electron current and ion saturation current at the wall.

Deflections of dynamic momentum flux and electron diamagnetic thrust in a magnetically steered rf plasma thruster

Two-dimensional characterization of the plasma plume is experimentally performed downstream of a magnetically steered radiofrequency plasma thruster, where the ion beam current, the ion saturation current, and the horizontal dynamic momentum flux, are measured by using the retarding field energy analyzer, the Langmuir probe, and the momentum vector measurement instrument, respectively, in addition to the previously measured horizontal thrust. The measurements show the deflections of the dynamic momentum flux including both the ions and the neutrals; the change in the direction of the dynamic momentum flux is consistent with the previously measured horizontal thrust. Furthermore, the ion saturation current profile implies that the deflected electron-diamagnetic-induced Lorentz force exerted to the magnetic nozzle contributes to the change in the thrust vector. Therefore, it is demonstrated that the deflections of both the dynamic momentum flux and the electron-diamagnetic-induced Lorentz force play an important role in the thrust vector control by the magnetic steering.

Optimization of accurate estimation of single diode solar photovoltaic parameters and extraction of maximum power point under different conditions

Introduction. With the snowballing requirement of renewable resources of energy, solar energy has been an area of key concern to the increasing demand for electricity. Solar photovoltaic has gotten a considerable amount of consideration from researchers in recent years. Purpose. For generating nearly realistic curves for the solar cell model it is needed to estimate unknown parameters with utmost precision. The five unknown parameters include diode-ideality factor, shunt-resistance, photon-current, diode dark saturation current, and series-resistance. Novelty. The proposed research method hybridizes flower pollination algorithm with least square method to better estimate the unknown parameters, and produce more realistic curves. Methodology. The proposed method shows many promising results that are more realistic in nature, as compared to other methods. Shunt-resistance and series-resistance are considered and diode constant is not neglected in this approach that previously has been in practice. The values of series-resistance and diode-ideality factor are found using flower pollination algorithm while shunt-resistance, diode dark saturation current and photon-current are found through least square method. Results. The combination of these techniques has achieved better results compared to other techniques. The simulation studies are carried on MATLAB/Simulink.

LANGMUIR PROBE TO CHARACTERIZE THE DUST PLASMA OF ALUMINUM OXIDE (AL2O3) PRODUCED BY DC PLASMA SYSTEM

In this research, we have conducted an experimental study of the dusty plasma to the Aluminum oxide (Al2O3) dust material with a grain radius of (0.2) µm to (0.6) µm. In the experiment, we use air in the vacuum chamber system under different low pressure (0.1-0.8) Torr. The results have showed that the existence of dust particles in air plasma is equal to the Paschen minimum which is (0.4) Torr with Al2O3 dusty and without dust. The effect of Al2O3 dust particles on the plasma characteristics like floating potential (Vf), plasma potential (Vp), electron saturation current (Ies), temperature of the electron (Te), density of electron (ne) and density of ion (ni) of the DC system that can be calculated in the glow-discharge region. Parameter measurements are taken by four cylindrical probes which are diagnosed at a distance of (40) mm from the cathode diameter, the Paschen minimum at a pressure of (0.4) Torr. The plasma potential and the probe's floating voltage become more negative when dust is immersed in the plasma region. The features of these parameters show that the current discharge decreases while the discharge voltage increases when the aluminum oxide dust particles that are incorporated. And vice versa was in the absence of dust. Electron density increases in the existence of dust particles which causes the electron temperature to decrease.

EVALUATION OF GROWTH AND SEED YIELD OF TWO CULTIVARS OF FLAX

In this research, we have conducted an experimental study of the dusty plasma to the Aluminum oxide (Al2O3) dust material with a grain radius of (0.2) µm to (0.6) µm. In the experiment, we use air in the vacuum chamber system under different low pressure (0.1-0.8) Torr. The results have showed that the existence of dust particles in air plasma is equal to the Paschen minimum which is (0.4) Torr with Al2O3 dusty and without dust. The effect of Al2O3 dust particles on the plasma characteristics like floating potential (Vf), plasma potential (Vp), electron saturation current (Ies), temperature of the electron (Te), density of electron (ne) and density of ion (ni) of the DC system that can be calculated in the glow-discharge region. Parameter measurements are taken by four cylindrical probes which are diagnosed at a distance of (40) mm from the cathode diameter, the Paschen minimum at a pressure of (0.4) Torr. The plasma potential and the probe's floating voltage become more negative when dust is immersed in the plasma region. The features of these parameters show that the current discharge decreases while the discharge voltage increases when the aluminum oxide dust particles that are incorporated. And vice versa was in the absence of dust. Electron density increases in the existence of dust particles which causes the electron temperature to decrease.

Ion current optimization in a magnetron with tunable magnetic field configuration

The response of the ion current in the substrate region to the magnetic system configuration of a circular magnetron was studied during direct current sputtering of aluminum target. The unbalancing degree induced by changing of magnets’ positions was modelled with finite element methods. The ion saturation current in the substrate region showed more than twofold variation with unbalancing degree in the range 0.6–1.2. The dependence was non-monotonic, and the system was optimized to maximize the substrate ion current. The Langmuir probe diagnostics showed plasma density ~ 1016 m−3 in the optimized magnetic configuration.

Investigation of the characteristics of ion saturation current in plasma over the keyhole in the process of electron beam welding

The energy spectra of the ion saturation current of the Langmuir probe in the plasma formed over the keyhole directly during the process of electron-beam welding of steel 09G2S with the varied parameters (e.g., the welding speed and focus coil current) has been investigated. The presence of typical zones with the energy spectrum peaks in the low-frequency and high- frequency bands has been shown. It has been established that the peak location in the high- frequency range of the energy spectrum does not depend on the welding modes and the position of the probes relative to the keyhole. The low-frequency range of the energy spectrum depends on the vapor flow density of the keyhole and is rather sensitive to the welding modes. The use of electron beam oscillation makes it possible to control plasma flows and hydrodynamic processes in the penetration channel.

The Research on Anti-DC current Transformer of Dual Iron Core Structure with Air Gap

Current transformer (CT) is wildly used in electrical measurement and relay protection. In order to improve the power system stability in DC bias, the CT performance of anti-DC is necessarily to be enhanced. Based on the Jiles-Atherton theory, the magnetization characteristics of iron core with different air gap was analyzed in this paper. A simulation model was established using the Simulink toolbox, and the ratio error and angle error were investigated in different air gap length. Simulation result shows that the maximum magnetic density of iron core almost stays uncharged with the addition of air gap. Furthermore the slope of magnetization curve decreased, which leads to the increase of iron core saturation current. Current transformer with closed and air gap iron core possesses a stable measurement error in condition of severe DC bias.

Pulsing Test for Defect of Resistive Word Line in DRAM Main Cell using WGFMU (Waveform Generator Fast Measurement Unit)

In this paper, we compare and describe the difference between the oscilloscope pulsing test and the WGFMU (Waveform Generator Fast Measurement Unit) in analyzing the defect of high resistance in DRAM main cell sample. The nanoprobe system has many constraints in the pulsing analysis utilizing the oscilloscope and pulse generator. There are certain cases where the system cannot support analysis when the saturation current is extremely minimal, such as the DRAM cell. In this paper, we address this constraint and propose a new way to conduct pulsing tests using the WGFMU's arbitrary linear waveform generator in the nanoprobe system.

The Effects of Optical Power of Semiconductor Laser on the Characteristics of Si-diode in an Exposed Device

In this paper, we experimentally studied the effects of optical power of semiconductor laser on the electrical properties of silicon diode of an exposed device. The experimental results showed that the laser diode light of different optical powers (2, 3, and 4 mW) had effects on the silicon diode that are somewhat similar to those of thermal treatment. A shift in the current-voltage curve to the left side was also noticed, which led to a non-linear decrease of the barrier voltage of the diode by the effect of laser light. We also reveal a decrease by 344.8 nA/mW in the reverse saturation current of the silicon diode as a result of exposure to laser light. The forward resistance of the silicon diode decreased with increased incident optical power. The value of the maximum current of diode increased by 0.5 A/W with increasing the optical power incident on the diode.