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The results from a wide-ranging parametric investigation into the behavior of the collisionless partially magnetized plasma discharge of three propellants—xenon, krypton, and argon—are reported in this two-part article. These studies are performed using high-fidelity reduced-order particle-in-cell (PIC) simulations in a 2D configuration that represents an axial–azimuthal cross-section of a Hall thruster. In this part I paper, we discuss the effects of discharge voltage and current density (mass flow rate). Our parametric studies assess the spectra of the resolved instabilities under various plasma conditions. We evaluate the ability of the relevant theories from the literature to explain the variations in the instabilities’ characteristics across the studied plasma parameter space and for various propellants. Moreover, we investigate the changes in the electrons’ cross-magnetic-field transport, as well as the significance of the contribution of different momentum terms to this phenomenon across the analyzed cases. In terms of salient observations, the ion acoustic instability (IAI)-related modes are found to be dominant across the simulation cases, with the ion transit time instability also seen to develop at low current density values. Across the explored parameter space, the instabilities have the main contributions to the electrons’ transport within the plume region. The peak of the electric momentum force term, representing the effect of the instabilities, overall shifts toward the plume as either the current density or the discharge voltage increases. The numerical findings are compared against relevant experimental observations reported in the literature.

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CrAlN coatings were synthesized on pre-plasma nitrided M2 high speed steels using different ion current densities. The effect of plasma nitriding pretreatment on the microstructures and tribological properties of composite CrAlN coatings had been studied. The results showed that the nitriding efficiency could be significantly enhanced by higher ion current density. The thickness of nitrided layer increased from 43 μm to 63 μm with the increase of ion current density. The nitrided layers without either compound layer or grain boundary precipitation were produced with all experimental ion current densities. Radial cracks also appeared at the Rockwell-C indentation edge of the composite CrAlN coating due to the conformal effect. Moreover, radial cracks of the composite coatings originated from the hard and brittle nitrided layer. The highest interfacial adhesion of the composite CrAlN coating reached 105 N. Furthermore, the wear resistance of CrAlN coating was improved by combining nitriding pretreatment with coating deposition, and the composite coating (PN 4 /CrAlN) possessed the superior wear resistant. [ABSTRACT FROM AUTHOR]

[Introduction] Multi power transmission lines arranged in the same corridor could avoid the land division and reduce the adverse effect on the local planning and development, but the personal safety of operators in the process of towers and conductors erection of subsequent power lines should be seriously considered as a result of induced voltage of the previous energized transmission lines. [Method] One DC transmission line under construction was taken as an example, electrostatic induced voltage generated from multi UHVDC transmission lines nearby in the same corridor were studied and calculated. The influence factors including the operating mode of UHVDC lines, line spacing from the energized power lines and length of stringing conductors were analyzed at the same time. [Result] The results show that the induced voltage got significantly high from adjacent UHVDC lines, and operation mode of energized lines played an important part; the less line spacing reduce, the higher induced voltage reach; the steady-state current from ion current density generated by UHVDC lines flowing through construction equipments have nearly less impact to constructors. Induced voltage of the stringing conductors will be paid much attention to when stringing and conductors and equipments should be grounded effectively. [Conclusion] The research results also have guiding significance to power lines′ construction which be adjacent to live lines.

The micro Hall thruster μHT-1 is designed for space gravitational wave detection missions, and the beam characteristics of the thruster are studied by experiments. A Faraday probe mounted on a three-dimensional moving platform is designed for diagnosing to obtain the beam current density distribution, and the operating conditions of the discharge voltage and the mass flow rate are adjusted in the range of 700∼1200 V and 0.1–0.5 sccm, respectively. In addition, the study further analyze the variation trends of total beam current, discharge current, utilization rate, divergence angle and others. The test results indicate that the μHT-1 thruster can work stably in a wide range of operating conditions, and the beam current expresses a good axisymmetric distribution. Meanwhile, the beam current density gradually decreases along the axial direction and spreads along the radial direction. The current utilization efficiency fluctuates from 53.4 % to 67.7 % when the power is adjusted in the range of 1.45–5.76 W, and the divergence angle increases from 41.3 ° to 56.7 °. The total beam current of the thruster shows a linear increase characteristics with the enhancing of the anode flow and the discharge voltage. • A new design, the outer diameter is 20 mm and the inner diameter is 15 mm • Work stably in a wide range of operating conditions. [ABSTRACT FROM AUTHOR]

The paper focuses on measurements of the total energy flux and normalized energy flux onto the substrate during high power impulse magnetron sputtering (HiPIMS) in a wide range of the pulse duration and discharge current. Al, Cr and Ti targets with a diameter 76 mm are used for sputtering. HiPIMS parameters include 1 kW discharge power, 15 to 150 А discharge current, 0.4–10 kHz pulse frequency, and 5–100 μs pulse duration. It is shown that the use of short pulses leads to ∼40 and 70% growth in the total energy flux onto floating and biased (−100 V) substrates, respectively. The energy per unit volume of the deposited coating increases by several times, if the pulse duration and the duty cycle are reduced. The paper examines reasons for the increased total and normalized energy fluxes onto the substrate observed after the pulse parameter modulation in the sputtering process. • Total and normalized energy fluxes onto the substrate are measured during HiPIMS. • Energy fluxes are measured depending on pulse's duration and duty cycle. • Influence of target material on energy fluxes onto the substrate is studied. • Use of short pulses leads to growth in the total energy flux onto substrate. • Normalized energy flux increases if the pulse duration and the duty cycle are reduced. [ABSTRACT FROM AUTHOR]

The influence of electron-beam parameters on the thickness and phase composition of a hardened layer formed upon the nitriding of austenitic stainless steel 12Cr18Ni10Ti in plasma produced by a beam in a low-pressure (3 Pa) nitrogen--argon mixture is studied. The results obtained in the DC and pulse-periodic modes of beam generation with the same mean current and electron energy are compared. In this case the negative bias voltage applied to the samples is 100 V. The nitriding temperature of 400°C is maintained at a mean beam current of 2.6 A and various combinations of frequency (100--500 Hz) and current pulse durations (0.1-0.3 ms) with an amplitude of 80 A. The mean ion-plasma current densities in the DC and pulsed modes are close in magnitude (2-3 mA/cm² at 400°C). The high pulsed ion-current density (35-70 mA/cm²) creates conditions under which the surface sputtering rate during the pulse exceeds the growth rate of the nitrided layer. The nitriding of steel in the pulsed and DC modes over four hours gives the same result. Hardened layers with a thickness of 7-8 µm and a microhardness of the surface component of 15 ± 1 GPa in which the main phase is a supersaturated nitrogen solid solution (expanded austenite) are formed. A possible explanation is that nitriding in an electron-beam plasma proceeds mainly under the action of long-lived active neutral nitrogen particles rather than as a result of ion bombardment. [ABSTRACT FROM AUTHOR]

The influence of conductor surface conditions of new and aged conductors on ground-level resultant electric field and ion current density is analyzed in this paper. The surface roughness and morphology of conductors are measured and analyzed by 3-D phase shift Micro-Xam (MicroXAM-3D) and scanning electron microscopy. Calculations are made using the upstream finite-element-finite difference method for the corona cage model to obtain the influence of surface conditions on the ion-flow field, consequently, changing the resulting electric field and ion current density. An indoor corona cage platform is build up to check the impact of surface conditions on the ground-level resultant electric field and ion current density in the laboratory. Considering the aging characteristics of the conductor surface, a typical \pm800 kV ultra-high voltage direct current transmission line is analyzed. The calculated results show that compared with the new conductor, the electric field and ion current density of the long-term operation conductors increase very significantly. [ABSTRACT FROM AUTHOR]

Filtered cathode vacuum arc deposition can remove the macroparticles produced from the cathode. Positively biasing the whole filter or inserting a biased plate in the filter can increase the plasma transport efficiency. We developed a curved magnetic filter with rectangular cross-section to improve the coating efficiency. In this study, the effect of biased plates at outer-wall and inner-wall on the transport efficiency of vacuum arc plasma through rectangular curved magnetic filter was investigated. A Langmuir probe system is used to measure the distribution properties of the filtered plasma at 15 places in the outlet plane of the filter. The results showed that a positively biased plate at inner-wall would increase the output ion current density and make the plasma concentrate to the middle of the outlet plane. [ABSTRACT FROM AUTHOR]

In order to improve the electromagnetic environment of ± 160 k V flexible HVDC transmission line, the calculation method of ground electric field and ion current density is elaborated respectively. The DC transmission line is simplified to the 2D structure and ground total electric field and ion current density of two kinds of aluminum cable steel reinforced named 1 × JL/LB1A-300/40 and 1 × JL/LB1A-630/45 are forecasted. Therefore the minimum height from conductor to ground is calculated, which provides theoretical basis for the line disconnection scope. [ABSTRACT FROM AUTHOR]

The high‐voltage direct current (HVDC) and HV alternating current (HVAC) hybrid transmission lines in the same corridor is an effective way to enhance the power transmission capacity of the corridor and save land resource. The transmission lines parameters such as the corridor width, the height of transmission lines, and electromagnetic environment can be analysed and optimised by the calculation of the hybrid ion‐flow field. In this study, nodal discontinuous Galerkin time‐domain method is for the first time applied to the calculation of the hybrid ion‐flow field. Furthermore, corona interactions between the HVDC and HVAC lines are considered in the process of numerical solution. Compared with measured results and previous methods, the proposed approach is verified to be able to obtain wiggle‐free numerical solution with significantly reducing the computational burden, and meanwhile, the calculation precision is increased greatly. The ground‐level electric field and ion current density of the hybrid lines in time domain are analysed, and then the time‐domain characteristic is explored. Finally, the ion‐flow fields of the hybrid ±800 kV DC/500 kV AC transmission lines in parallel and on the same tower have been made a comparative analysis and optimisation, which provide theoretical basis for real hybrid towers design. [ABSTRACT FROM AUTHOR]

This paper deals with the electric and hydrodynamic confinement of negative ions in a point-to-plane corona discharge gap. Radial ion current density profiles have been measured on the earthed planar electrode, drilled in the axis of the point. The experimental setup is first validated by comparison with the Warburg's law without injected gas flow rate. The gas injected in the gap and blown from the discharge gap through the hole located at the centre of the plane affects neither the electric field close to the point nor the subsequent electric wind. However, it leads to the confinement of ions flux towards the central symmetry axis in the low electric field region up to a critical gas velocity, which for no more effect is measurable. Hence, electro hydro-dynamics confinement of ions can be achieved by limiting the outward radial expansion of ions to increase ion current densities on specific locations close to the low field planar electrode. [ABSTRACT FROM AUTHOR]

A comparative study of deposition rate, adhesion, structural and electrical properties of nanocrystalline copper thin films deposited using direct current magnetron sputtering (DCMS) and different regimes of high power pulsed magnetron sputtering is presented. High-power impulse magnetron sputtering (HIPIMS) and burst regime (pulse packages) of magnetron sputtering are investigated. The ion and atomic flows toward the growing film during magnetron sputtering of a Cu target are determined. X-ray diffraction, scanning electron microscopy and atomic force microscopy were used to observe the structural characterization of the films. The resistivity of the films was measured using four-point probe technique. In all sputtering regimes, Cu films have mixture crystalline orientations of [111], [200], [311] and [220] in the direction of the film growth. As peak power density in studied deposition regimes was different in order of magnitude (from 15 W/cm in DC regime to 3700 W/cm in HIPIMS), film properties were also greatly different. DCMS Cu films exhibit a porous columnar grain structure. In contrast, HIPIMS Cu films have a slightly columnar and denser composition. Cu films deposited using burst regimes at peak power density of 415 W cm and ion-to-atom ratio of about 5 have the densest composition and smallest electrical resistance. [ABSTRACT FROM AUTHOR]

The paper studies a new method in vacuum-arc deposition technology that can be called short pulse-enhanced vacuum arc evaporation (s-PEVAE). This deposition technique combines sub-microsecond high-current pulsed and direct current operation of the arc-discharge source with the pulse frequency of several kilohertz. The high pulse voltage provides a high growth rate and amplitude of discharge current pulses, i.e., over 109 А/s and 1 kА, respectively. During the s-PEVAE process, the arc discharge power can achieve several hundreds of kilowatts. According to optical and probe measurements performed during the titanium evaporation in argon gas, ionization provided by s-PEVAE is higher than that provided by direct current vacuum arc evaporation (DCVAE). In s-PEVAE, the increase in the average discharge power is accompanied by the growth in the average density of the substrate ion current. At the same time, the deposition rate of the titanium coating decreases. All this leads to a significant change in the ratio between the ions bombarding the substrate and metal atoms forming the coating. Along with the substrate bias voltage, this ratio exerts a strong effect on the structure and properties of the deposited coating and can be controlled by the pulse parameters such as amplitude, time, and frequency. • Short pulse-enhanced vacuum arc evaporation (s-PEVAE) process was studied. • High growth rate (109 А/s) and amplitude (1 kА) of discharge current were obtained. • s-PEVAE process was compared with direct current vacuum arc evaporation (DCVAE). • s-PEVAE provided the higher ionization and ion-to-atom ratio than the DCVAE. [ABSTRACT FROM AUTHOR]

Ions generated by corona discharge of high‐voltage direct current (HVDC) transmission lines exist in the space between conductors and the ground. Electric field strength, ion current density, and space charge density are significant electromagnetic environment parameters of HVDC transmission lines. To measure the charge densities at ground level under the HVDC power lines, an aspirator‐type charge meter is designed and utilised. The charge meter is calibrated in the ionised field generated by parallel metal mesh and plate. Charge densities on the ground under the unipolar HVDC conductor are measured by the calibrated devices in the laboratory. Experimental results show that reasonable agreement between measured data by the devices and the ones by field mills and ion current plates could be obtained, which establishes a foundation to research the charge characteristics of ions near the ground. [ABSTRACT FROM AUTHOR]

The possibility for DC and AC power lines running parallel to each other, sharing the same right‐of‐way or even the same tower has been increased in China. In this work, the coupled DC and AC electric field effects are analysed with a reduced‐scale model. Improved measuring methods are proposed to obtain both the DC and AC components of the ground level electric field and ion current density. Depressing effects of the AC field on the ground level DC field and of the DC field on the ground level AC field are observed when the applied DC voltage exceeds the onset value. The mechanism of the influences of AC power lines on the nearby DC power lines is analysed with experiments and simulations. Both the influence of the AC field on the corona onset on the surfaces of DC conductors and the influence of the AC field on the motion of the space charges are proved to be important in the field effects under the hybrid lines. [ABSTRACT FROM AUTHOR]

Sharing the same corridor of the HVAC and HVDC transmission lines can efficiently increase the power transfer capacity of the limited corridor and will be erected in East China. An accurate and efficient numerical analysis method for analyzing the ion-flow field of the ac–dc hybrid lines is helpful for engineering design. In this paper, an upwind finite volume-based algorithm for the solution of the ac–dc hybrid ion-flow field is proposed, which can take the influence of the space charges generated by corona into account. The electric field is solved by the charge simulation method and the finite-element method, while the advection and recombination effects of the space charges are solved by a time-dependent finite volume method. The reduced-scale ac–dc hybrid models are analyzed and the calculating results by the proposed approach in this paper have good agreements with the experimental ones in the literature and in this paper. Finally, the ground-level electric field and ion current density of the hybrid UHVAC and UHVDC transmission lines in parallel are analyzed, providing a reference for the engineering design. [ABSTRACT FROM AUTHOR]

Abstract: SiOx thin films synthesized on polycarbonate substrates by low temperature plasma processes are electronically meta-stable because the process temperature (<70 °C) needed to prevent deterioration of the polymer substrate is too low to allow the formation of a thermodynamically stable structure with stoichiometric electronic bonding. Therefore, the surfaces are very active and react chemically with the environment after scratching and pressure. This paper reports a coating method for producing dense structures with high hardness and good optical properties by controlling the ion current density (ion flux). The ion current density (ion flux) on the substrate was controlled by the RF power and additional bias with a bipolar pulsed dc frequency. [Copyright &y& Elsevier]

Abstract: Silicon oxide gas barrier films were deposited on polyethylene terephthalate (PET) substrates by plasma enhanced chemical vapor deposition (PE-CVD) for applications to transparent barrier packaging. The barrier properties of the silicon oxide coated film were optimized by varying the bias conditions and input power in the radio frequency plasma. The plasma diagnostics, ion current density and substrate temperature were characterized by optical emission spectrometry (OES), an oscilloscope and thermometer, respectively. The coating properties were examined by Fourier transform infrared (FT-IR) spectroscopy and the water vapor transmission rate (WVTR). A high intensity of O and H ions and a high ion current density (ion flux) with a low temperature plasma process were found to be suitable for improving the barrier properties of the silicon oxide film coatings. The Si–O cage-like structure adversely affected the gas barrier properties of the deposited coating. The energy provided by ion bombardment (ion flux) can induce changes in the film density and composition similar to those that may occur by the increase in deposition temperature through rf bias. In addition, the film properties depend not only on a high ion current density (ion flux) and input power, but are also related to a silicon oxide film with a widely distributed planar ring size. [ABSTRACT FROM AUTHOR]

Abstract: The combination of microbeam implantation and in-situ micro RBS/channeling analysis in the Rossendorf nuclear microprobe facility enables crystal damage studies with high current densities not achievable in standard ion implantation experiments. Si(100) samples were implanted with 600keV Si+ ions and a fluence of 1×1016 cm−2. Using a beam spot of 200μm×200μm current densities from 4 to 120μA/cm2 were obtained. The substrate temperature was varied between RT and 265°C. The implanted regions were subsequently analysed by micro RBS/channeling with a 3MeV He+ beam having a spot size of 50μm×50μm. Crystal damage up to amorphisation was observed in dependence on the substrate temperature. Above a critical temperature T C no amorphisation occurs. T C was determined for each series of samples implanted with the same ion current density j. It was found that the empirical Arrhenius relation j ∼exp(−E a/kT C), known from standard implantation experiments, is also valid at high current densities. The observed Arrhenius law can be derived from a model of epitaxial crystallisation stimulated by defect diffusion. [Copyright &y& Elsevier]

The corona generated from high-voltage direct-current transmission lines can induce the ion around the lines, which will increase the electric field and the ion current density and influence the environment nearby. Based on the finite-element method, an iterative algorithm to analyze the electric field and the ion current density at the ground level generated from the bundled conductors of bipolar lines is proposed. After the validity of the method is testified, some examples are analyzed. The method has been used to design ±800 kV transmission lines system in China. [ABSTRACT FROM AUTHOR]

As shown in previous publications concerning cathodic arc deposition, the vacuum arc as a technological tool can be very complexly influenced by variation of the electrical arc parameters. The pulsed arc current and the resulting ion current influence the formation of the coating. To determine optimised parameters for the deposition process, the dependence on the frequency, on the rate of current rise and on the maximum pulse current in particular were investigated. Using the variation of the output parameters of a pulsed arc power supply, the ion current was steered in its shape and its absolute values. Therefore, the shape of arc current pulses was varied, especially in the phase of rise and fall (triangle, sine, rectangle). Among other things, it was noted that at the beginning of the pulse an excessive increase in ion current is measurable. In order to use this increase for a more effective coating process, experiments were carried out using pulses with controlled slopes and current levels or double pulses of rectangular shape. The examinations have shown that an increase in the ion current ratio in the arc current can be reached by a suitable choice of the electrical parameters. The plasma can be controlled by the electrical parameters of the current source. [Copyright &y& Elsevier]