Cathode Diameter Research Articles

Fabrication Characterization of Solar-Cell Silicon Wafers Using a Circular-Rhombus Tool

A new recycling fabrication method using a custom-built designed circular-rhombus tool for a process combining of micro-electroetching and electrochemical machining for removal of the surface layers from silicon wafers of solar cells is demonstrated. The low yields of epoxy film and Si3N4 thin-film depositions are important factors in semiconductor production. The aim of the proposed recycling fabrication method is to replace the current approach, which uses strong acid and grinding and may damage the physical structure of silicon wafers and pollute to the environment. A precisely engineered clean production approach for removal of surface microstructure layers from silicon wafers is to develop a mass production system for recycling defective or discarded silicon wafers of solar cells that can reduce pollution and cost. A large diameter cathode of the circular-rhombus tool (with a small gap between the anode and the cathode) corresponds to a high rate of epoxy film removal. A high feed rate of the silicon wafers combined with a high continuous DC electric voltage results in a high removal rate. The high rotational speed of the circular-rhombus tool increases the discharge mobility and improves the removal effect associated with the high feed rate of the workpiece. A small port radius or large end angle of the rhombus anode provides a large discharge space and good removal effect only a short period of time is required to remove the Si3N4 layer and epoxy film easily and cleanly.

Nickel Nano-Probe Shape Control Using a Ring Cathode

sition metal probes, which are scientifically and technologically important as mentioned above. In this study, we systematically investigated the change in the nickel nano-probe shape by varying the ring cathode diameter of an etching apparatus and the applied bias voltage between the cathode ring and the anode nickel wire. We found that the nickel probe shape varied with the shape of the hanging electrolyte membrane and with the diusion behavior of electrolytes and byproducts. The membrane shape and the diusion behavior depend on the ring diameter and the applied bias voltage. This study clearly shows that the shape of the etched nano-probe is controllable.

Hollow cathode fall field strength measured by Doppler-free two-photon optogalvanic spectroscopy via Stark splitting of the 2S level of hydrogen

It has recently been demonstrated that Doppler-free two-photon optogalvanic spectroscopy is very well suited to measure the strong electric field strength (0.4 kV/cm to 4 kV/cm) present in the cathode fall of hollow cathode discharges, via the Stark splitting of the 2S level of atomic hydrogen and its isotopes. Based on an improved reliability and precision of the measurements, the aim of the present study is to analyze more deeply the dependence of the cathode fall behaviour for a hydrogen discharge on the usual discharge parameters like gas pressure and discharge current; and for changes of the discharge geometry using two different cathode diameters of 10 mm and 15 mm.

Theoretical investigation of plasma immersion ion implantation of cylindrical bore using hollow cathode plasma discharge

Plasma immersion ion implantation of the internal surface of a cylindrical bore with a small diameter is difficult. The use of radio-frequency hollow cathode discharge as the internal plasma source for ion implantation is proposed. The implantation dynamics and plasma sheath expansion are investigated numerically using the particle-in-cell model. The inner diameter of the tube in our simulation is 20 mm and the external diameter of the hollow cathode is 12 mm. Three electric field zones are observed due to the existence of the electrode with ground potential in the tube. The ions undergo acceleration in the region close to the hollow cathode, maintain their velocity in the zone without the electric field due to overlapping of the plasma sheath, and decelerate in the region near the open end of the tube. Most of the ions are implanted into the surface away from the open plane of the hollow cathode. This is attributed to the special configuration of vertical electric field. The simulation results have demonstrated that plasma immersion ion implantation using a hollow cathode can be effectively applied to the treatment of the inner wall of a cylindrical bore, especially the ones with a small diameter.

Performance of the Micro-SOFC Module Using Submillimeter Tubular Cells

A micromodule, the size of was fabricated using three micro-solid oxide fuel cell (SOFC) bundles which consist of anode-supported microtubular SOFCs of diameter and porous cathode matrices. The module was designed to apply to small-sized power sources at a low operating temperature under . The open-circuit voltage of the module depended upon the operating temperatures, the lower for higher temperature due to the use of a ceria-based electrolyte. Maximum power outputs of the module were 0.5, 0.9, and at 450, 500, and operating temperatures, respectively, where the air was applied only by natural convection. As a result, the performance of the module turned out to be over at operating temperature. The results also showed a strong influence of the fuel flow rate; the higher rate led to an increased performance due to improved gas transport.

Characterization and investigation of the anomalous behavior of the immersed-Bz diode during operation at 4 to 5 MV

The immersed-Bz diode is being developed as a high-brightness, flash x-ray radiography source at Sandia National Laboratories. This diode is a foil-less electron-beam diode with a long, thin, needlelike cathode which is inserted into the bore of a solenoid. The solenoidal magnetic field guides the electron beam emitted from the cathode to the anode while maintaining a small beam radius. The electron beam strikes a thin, high-atomic-number anode and produces forward-directed bremsstrahlung. In addition, electron beam heating of the anode produces surface plasmas allowing ion emission. Two different operating regimes for this diode have been identified: A nominal operating regime where the total diode current is characterized as classically bipolar with stable impedance [see D. C. Rovang et al., Phys. Plasmas 14, 113107 (2007)] and an anomalous operating regime characterized by a rapid impedance collapse where the total diode current greatly exceeds the bipolar limit. The operating regimes are approximately separated by cathode diameters greater than 3mm for the nominal regime and less than 3mm for the anomalous impedance collapse regime. Results from a comprehensive series of experiments conducted at 4–5MV characterizing the transition from this nominal operating regime to the anomalous operating regime as the cathode diameter is reduced are presented. Results from experiments investigating the effects of anode-cathode gap, anode material, and cryogenic modification of the anode surface are also presented. Although these investigations were unsuccessful in completely mitigating the anomalous behavior, insight gained from these experiments has elucidated several key physics issues that are discussed.

Highly efficient electron beam generation in a wide-aperture discharge in helium

The paper deals with a gas discharge having electron beam generation efficiency η≃100% at a voltage U>300 V. The discharge has been realized in helium in a cell with a cathode diameter of 19.5 cm. The discharge features are a higher η as compared to other discharges, the presence of reverse bends in the voltage-current characteristics including the occurrence of a falling section, and nonmonotony in η(U) and its growth with increasing He pressure. The discharge peculiarities are explained by its photoemissive nature. The basic contribution to the photoemission is made by the emission from the resonance state excited in the secondary processes.

Three-Dimensional Striations of a Glow Discharge

This paper presents the observation of the luminosity of stratified glow discharges with small anode (3 mm in diameter) and different geometries of the cathodes. The following geometries have been tested: 1. cylindrical chamber that is 50 cm in diameter and 60 cm in height, with an anode placed in the center; 2. ring cathode (diameter of 15 cm and width of 1 cm) inside of a spherical glass chamber that is 30 cm in diameter; and 3. ring cathode (diameter of 20 cm and a distance between glass plane windows of 2 cm). All photos were obtained for (1 : 1) air-acetone mixture.

Effect of cathode diameter on intense relativistic electron beam generation in the presence of prepulse

Intense gigawatt relativistic electron beam generation studies were carried out in the presence of prepulse. Electron beams were generated using planar and annular graphite cathodes of various diameters at a fixed 25mm anode-cathode gap. For the planar cathode, the beam parameters obtained are 340keV, 24kA, and 100ns at a 680A∕cm2 current density. With an annular cathode, 346keV, 10kA, and 100ns electron beam could be generated at a 3.4kA∕cm2 current density. The peak electric field in the diode varies from 58to138kV∕cm. A bipolar prepulse voltage has been recorded at the diode for both the cathodes. The amplitude of the negative prepulse voltage varies with the Marx generator voltage but the time duration remains same. The positive prepulse voltage varies both in amplitude and time duration with the Marx generator voltage. Some shot to shot variation in the diode voltage and current were recorded for the annular cathode due to the nonreproducibility of the prepulse generated plasma. It was found that the effect of prepulse is more pronounced in the cathode of larger diameter.

Total impulse improvement of coaxial pulsed plasma thruster for small satellite

Research and development on pulsed plasma thruster (PPT) for small satellites has been conducted in Tokyo Metropolitan University (TMU). A PPT with coaxial electrode and PTFE cavity has been considered to gain larger impulse bit than that of parallel plate PPT. In this paper, the objectives are development of the PPTs with large impulse bit and large total impulse, to apply to a propulsion system for a small satellite. The electrodes and the propellant configuration were considered. As a result, divergent nozzle and larger cathode diameter improved thrust performances and larger impulse bit from 300 to 800 μNs was achieved. And the current reversal was appeared remarkable as its operation accumulated. Then, propellant-feeding mechanism was considered to improve its total impulse. With exchange of five propellants in each 20,000 shots, total impulse of 40 Ns was obtained. These results indicate that the PPT developed in TMU would provide various missions for a small satellite.

Mechanism of Design of the Precision Recycle Process of a Color Filter Using Electrochemical Etching

An effective and low-cost mechanism is presented which uses electrochemical etching and design-tool electrodes as a precision recycle process of indium-tin-oxide (ITO) layer removal from the color filter surface of an optoelectronic flat-panel display instead of chemical etching. Through the ultraprecise removal of thin-film microstructure, the semiconductor optoelectronics industry can effectively recycle defective products, thereby reducing production costs. In the current experiment, the author uses a fifth-generation thin-film transistor liquid-crystal display. A large cathode diameter accompanied by a small gap width between the cathode and the workpiece takes less time for the same amount of ITO layer removal. An adequate color filter feed rate combined with sufficient electric power produces a fast etching effect. A higher electrode rotational speed, a higher temperature, or a higher concentration of the electrolyte corresponds to a higher etching rate for the ITO layer. Pulsed direct current can improve the effect of dreg discharge and is advantageous when combined with fast workpiece feed rate. However, this raises the current rating. In a short amount of time, electrochemical etching can remove the ITO layer easily and cleanly.

Stability and current behaviour in semiconductor gas discharge electronic devices

Breakdown and range of stable discharge glow in a homogeneous dc electric field are studied at various distances d between the electrodes and different inner diameters D (5, 9, 12, 18 and 22 mm) of GaAs semiconductor cathode areas. The current–voltage characteristics of the gas discharge system have been studied in a wide range of pressure p (16–760 Torr), interelectrode distances d (10 µm–5 mm) and conductivities of the GaAs cathode. The initiation of electrical breakdown as a result of secondary electron emission from the semiconductor cathode in low gas pressure is presented in this paper. In a planar gas discharge cell with diameters much larger than an interelectrode distance, the effects of different parameters (overvoltage, electrode separation, diameter and conductivities of the GaAs cathode, gas pressure, glow current, etc) on electrical breakdown and spatial stabilization of the current have been studied. The distributed resistance of photosensitive semiconductor cathode and the impact of the ionizing component of the discharge plasma on the control of the stable operation of a planar gas discharge system at atmospheric pressure are also investigated. Through spatially uniform irradiation of the semiconductor cathode, non-stationary states which are non-homogeneous can be generated in a system. The loss of stability is primarily due to the formation of a space charge of positive ions in the discharge gap which changes the discharge from the Townsend to the glow type.

The influence of products and by-products obtained by drinking water electrolysis on microorganisms

It is the aim of this work to underline the chemical character of disinfection processes and to present the results of treatment experiments for artificially and electrochemically added chemicals focusing on chlorine components and hydrogen peroxide obtained on IrO 2/RuO 2 anodes. A discontinuous cell with rotating anode placed 4 mm above an IrO 2 expanded mesh cathode of same diameter was used for the generation of electrolysis products. The thermostated experiments were carried out at a temperature of 20 °C and in constant current mode. Artificial solutions prepared using sodium salts and deionised water were electrolysed. Samples were analysed using the DPD ( N, N-diethyl- p-phenylendiamine) method. Escherichia coli K-12, Bacillus subtilis DSM 2277 and Saccharomyces cerevisiae Kolin were used as test-microorganisms. Morphological changes were studied using transmission electron microscopy. The results show that electrolysed water had a higher lethal efficiency than Ca(OCl) 2 of the same measured active chlorine concentration. During the killing period mainly inner cell parts of the microorganisms react chemically with the disinfectants. In sufficiently high concentrations and reaction times, the cell material continues to react. Cell walls or membranes can break-through as electron microscopy pictures show. Electrolysed water had a higher lethal efficiency on microorganisms. This behaviour demonstrates the existence of additional by-products.

Specific features of wide-aperture glow discharge in helium

The characteristics of wide-aperture discharge in helium have been studied for a cathode diameter of 19.5 cm and a cathode-grid anode distance of 3 cm. It is established that the properties of discharge in this system are substantially different from those of a usual abnormal discharge. The difference is manifested in the bending of current-voltage characteristics, their pronounced dependence on the helium pressure, a nonmonotonic dependence of the electron beam generation efficiency η on the discharge voltage U, and an anomalously high efficiency (η ≈ 100%) in the range of U ≈ 350–1000 V.

High-Power Self-Pinch Diode Experiments for Radiographic Applications

We report here on self-magnetic-pinch diode experiments at voltages from 3.5 to 6 MV. In addition to electrical diagnostics, the diode is characterized as a radiation source by dose and spot-size measurement. As the operating voltage increases, we find that a given diode geometry tends to produce a smaller spot but suffers from the reduced impedance lifetime. Optimization involves increasing the cathode diameter and diode gap as the voltage increases. We find a good quantitative agreement with the Monte Carlo code integrated tiger series over the entire data set, assuming an effective electron incidence angle of 20deg. Over this range, we observe favorable dose and spot scaling of optimized diode performance with voltage. Our best results are roughly 200-rad at 1 m with an ~2-mm-diameter spot. These were obtained at diode parameters of roughly 6 MV, 150 kA, and 30-ns radiation full-width at half-maximum.

Measurement of cathode surface temperature using the method of CCD imaging in arc discharge

A two-wavelength pyrometry device using ordinary array CCD (charge coupled device) to collect the radiation data in the horizontal and vertical directions has been developed for measuring the cathode surface temperature during the arc discharge. Analyses of experimental results show that the device can make the measurement of the cathode surface temperature feasible. The cathode surface temperatures measured are lower than the melting point of tungsten (3653 K), and the arc current, cathode diameter, and the cathode length are the main influencing factors of the cathode surface temperature.

Removal of heavy metals from kaolin using an upward electrokinetic soil remedial (UESR) technology

An upward electrokinetic soil remedial (UESR) technology was proposed to remove heavy metals from contaminated kaolin. Unlike conventional electrokinetic treatment that uses boreholes or trenches for horizontal migration of heavy metals, the UESR technology, applying vertical non-uniform electric fields, caused upward transportation of heavy metals to the top surface of the treated soil. The effects of current density, treatment duration, cell diameter, and different cathode chamber influent (distilled water or 0.01 M nitric acid) were studied. The removal efficiencies of heavy metals positively correlated to current density and treatment duration. Higher heavy metals removal efficiency was observed for the reactor cell with smaller diameter. A substantial amount of heavy metals was accumulated in the nearest to cathode 2 cm layer of kaolin when distilled water was continuously supplied to the cathode chamber. Heavy metals accumulated in this layer of kaolin can be easily excavated and disposed off. The main part of the removed heavy metals was dissolved in cathode chamber influent and moved away with cathode chamber effluent when 0.01 M nitric acid was used, instead of distilled water. Energy saving treatment by UESR technology with highest metal removal efficiencies was provided by two regimes: (1) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 mm, duration of 18 days, and constant voltage of 3.5 V (19.7 kWh/m 3 of kaolin) and (2) by application of 0.01 M nitric acid as cathode chamber influent, cell diameter of 100 cm, duration of 6 days, and constant current density of 0.191 mA/cm 2 (19.1 kWh/m 3 of kaolin).

A new atmospheric RF cold plasma source with microhollow cathode structure

The configuration and mechanism of a microhollow cathode discharge (MHCD) is introduced in this paper. The focus is a new type of cold atmospheric large-area plasma source, the fused hollow cathode (FHC) plasma source based on radio frequency hollow cathodes. Through its applications and related research, we present the characteristics of the hollow cathode discharge and the factors on which its characteristics depend, such as the cathode material, gas specy, frequency, gas flow, pressure, inner diameter of cathode, and the like. Two other types of related MHCD systems are given in addition.

The plasma source of the Large Plasma Device at University of California, Los Angeles

The Large Plasma Device at the University of California, Los Angeles has recently been upgraded. The plasma is now 18m long (the device is 22m long) and is designed to produce a 0.36T axial magnetic field. Its plasma source has also been upgraded, incorporating a 1m square heater, a 72cm diameter cathode and anode, and associated heat shields and reflectors. The barium oxide coated cathode is heated to 750°C and can produce plasmas of diameters up to 0.9m diameter (depending on the magnetic field configuration), and densities up to 7×1012cm−3 with a spatial uniformity of ±10%.

A Vapor-Air Discharge between Electrolytic Anode and Metal Cathode at Atmospheric Pressure

An experimental investigation is performed of the structure, mechanism, and electrical and thermal characteristics of a vapor-air discharge between an electrolytic anode (EA) and a metal cathode (MC) in a wide range of parameters at pressure P = 8×104 to 105 Pa, current I = 0.02 to 60 A, interelectrode spacing l = 0.1 to 40 mm, and metal cathode diameter d c = 1 to 40 mm. The main types of vapor-air discharge with EA are identified. The possibility of burning of a multichannel discharge between a metal cathode and an electrolytic anode at atmospheric pressure is demonstrated for the first time, and a vapor-air discharge with a diffuse plasma column is investigated at high currents and large interelectrode spacings. It is determined that the electrical and thermal characteristics depend significantly on current, interelectrode spacing, electrolyte composition and concentration, geometric shape, diameter, and cooling of the MC. The significant effect of the vapor-air discharge on the electrolytic anode surface is revealed. Transverse waves are observed on the electrolyte surface. Significant turbulent mixing is observed for the first time on the electrolyte-plasma interface in the case of a vapor-air discharge with electrolytic anode at atmospheric pressure and high currents.