Auxiliary Anode Research Articles

Local cathodic protection design based on numerical simulation

Purpose – The purpose of this investigation was to study these problems and design regional cathodic protection, using numerical simulation. Regional cathodic protection technology is immature at home and abroad. This is reflected in the fact that in gas stations, there are many underground pipelines, which can lead to serious interference and shielding phenomena, and there are many grounding networks that can cause substantial loss of the cathodic protection current. Design/methodology/approach – Based on the above, in this article, first of all, the mathematical model of the buried pipeline cathodic protection potential distribution was established and the control equations solved using the boundary element method. Second, the cathodic shielding effect in pipeline concentration areas, the effect of instrument equipment grounding systems on cathodic protection and the influence of DC stray current on the interference of pipeline corrosion were studied separately using BEASY software. Finally, the BEASY software was used for a regional cathodic protection design for a real gas station. Findings – It was concluded that impressed current used in combination with sacrificial anodes for regional cathodic protection design is often the most economic and effective approach. However, the output current of the auxiliary anode is large with high energy consumption. In consequence, it may be recommended that the station pipelines should be laid on the ground, rather than under it. Originality/value – It is considered that the results can guide regional cathodic protection design for real-life installations very well.

Modeling and Control of Impressed Current Cathodic Protection (ICCP) System

The corrosion of metallic structures buried in soil or submerged in water which became a problem of worldwide significance and causes most of the deterioration in petroleum industry can be controlled by cathodic protection (CP).CP is a popular technique used to minimize the corrosion of metals in a variety of large structures. To prevent corrosion, voltage between the protection metal and the auxiliary anode has to be controlled on a desired level. In this study two types of controllers will be used to set a pipeline potential at required protection level. The first one is a conventional Proportional-Integral-Derivative (PID) controller and the second are intelligent controllers (fuzzy and neural controllers).The results were simulated and implemented using MATLAB R 2010a program which offers predefined functions to develop PID, fuzzy and neural control systems.

Improving the Localization of Surface Texture by Electrochemical Machining with Auxiliary Anode

Surface texture can be generated by through-mask electrochemical micromachining. However, the machining localization deteriorates by the lateral undercutting under the mask. In this article, the auxiliary anode was consisted in the mask to reduce the lateral undercutting to improve localization of the surface texture. Numerical simulation of the current density distribution in the interelectrode gap was used to theoretically verify the proposed method, and the effect of the auxiliary anode on the localization was investigated experimentally. The experimental results indicated that the machining localization could be significantly improved by the auxiliary anode, and the etch factor was decreased with the increasing machining voltage.

Numerical Simulation of Cathodic Protection Potential Distribution of Coastal Power Plant Condenser Based on Physical Scale Model

Finite element numerical simulation software was used for numerical simulation analysis of cathodic protection of coastal power plant condenser based on physical scale model. The effects of location, size and number of auxiliary anode on the cathodic protection potential distribution of the condenser were studied, which would predict cathodic protection result of the condenser and provide reasonable design for cathodic protection of the condenser.

Sharp transition between two regimes of operation of dc discharge with two anodes and thermionic emission from cathode

In a dc discharge plasma with two anodes and thermionic emission from cathode, the two anodes are used for plasma control. The main anode is placed between the cathode and the other auxiliary anode has a circular opening for passing electron current from the cathode to the second anode. It is experimentally demonstrated that a plasma may exhibit a sudden transition between two quasi-stable conditions as one increases the cathode-electron current collected by the auxiliary anode through an aperture, i.e., hole, in the main anode. In one regime, a bright glowing “ball-shaped double layer” appears on the plasma side having a potential drop of 10–15 eV and concomitant ionization in the neighboring region attached to the opening. The second regime is characterized by a uniform potential profile in plasma and an absence of the ball-shaped double layer. The transition between these regimes is accompanied by a significant change in plasma properties, such as the electron energy distribution function (EEDF). Controlling the EEDF is a valuable capability in technological applications. Increasing the gas pressure leads to the elimination of the first regime for sufficiently high gas pressure, the threshold being a few Torr. The disappearance of a regime transition can be explained by invoking an EEDF transition, from being nonlocal at low pressure to becoming local at high pressure. Local EEDF is determined by local values of electric field. Nonlocal EEDF is determined by electric field values elsewhere, and the electron can travel without energy loss over a path much longer than the discharge dimension.

Modeling a short dc discharge with thermionic cathode and auxiliary anode

A short dc discharge with a thermionic cathode can be used as a current and voltage stabilizer, but is subject to current oscillation. If instead of one anode two anodes are used, the current oscillations can be reduced. We have developed a kinetic model of such a discharge with two anodes, where the primary anode has a small opening for passing a fraction of the discharge current to an auxiliary anode. The model demonstrates that the current-voltage relationship of the discharge with two anodes is characterized everywhere by positive slope, i.e., positive differential resistance. Therefore, the discharge with two anodes is expected to be stable to the spontaneous oscillation in current that is induced by negative differential resistance. As a result, such a discharge can be used in an engineering application that requires stable plasma, such as a current and voltage stabilizer.

Research on the Feasibility of Ion Nitriding for Inside Walls of Big Length-Radius-Ratio Oil Pipelines

In order to increase the lifetime of oil pipelines with a length-radius ratio of 153, a special ion nitriding experiment instrument with “auxiliary anode” was designed for nitriding pipelines inside walls. The research and test results indicated that the nitriding depth and surface hardness were increased. Field tests showed that the lifetime of such treated oil pipelines increased by more than five times. This technology offered a new surface strengthening method for increasing the anticorrosive ability, wearable ability and lifetime of oil pipelines in petroleum exploitation industry.

P‐44: Patterned Microlens‐Array Films Assisted with Auxiliary Electrodes for Luminance Improvement in Large‐Area OLEDs

AbstractThe auxiliary or supporting electrodes are often utilized for the large‐emitting‐area OLEDs for better electrical properties. However, the auxiliary electrodes also blocked or absorbed the light from the emitter. In our optical simulation, we present the partitioned OLED units with the grid‐type auxiliary anode and patterned or center‐hollowed microlens‐array films to obtain more than 141.7% in relative luminance at normal direction.

Ammonia inhibition of electricity generation in single-chambered microbial fuel cells

Batch experiments are conducted at various concentrations of initial total ammonia nitrogen (TAN) with acetate as an electron donor to examine the effects of free ammonia (NH 3) inhibition on electricity production in single-chambered microbial fuel cells (MFCs). This research demonstrates that initial TAN concentrations of over 500 mg N L −1 significantly inhibit electricity generation in MFCs. The maximum power density of 4240 mW m −3 at 500 mg N L −1 drastically decreases to 1700 mW m −3 as the initial TAN increases up to 4000 mg N L −1. Nitrite and nitrate analysis confirms that nitrification after complete acetate removal consumes some TAN. Ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) are also inhibited by increasing the initial TAN concentrations. Another batch experiment verifies the strong inhibitory effect of TAN with only small differences between the half-maximum effective concentration (EC 50) for TAN (894 mg N L −1 equivalent to 10 mg N L −1 as NH 3) and optimum TAN conditions; it requires careful monitoring of the TAN for MFCs. In addition, abiotic control experiments reveal that granular activated carbon, which is used as an auxiliary anode material, adsorbs a significant amount of ammonia at each TAN concentration in batch MFCs.

Passive electrode effect reduces defibrillation threshold in bi-filament middle cardiac vein defibrillation

To investigate whether a passive electrode effect decreases defibrillation threshold (DFT) in multi-filament middle cardiac vein (MCV) defibrillation. Twelve pigs underwent active housing (AH) insertion, with defibrillation coils placed transvenously in right ventricular apex and superior vena cava. The MCV was cannulated, and 1.12F, 50 mm coil electrodes (Ela Medical SA, France) were deployed in its right and left branches. Lead placement was possible in 11 of 12 animals. DFT (J, mean +/- SD) was determined by three-reversal binary search and compared between the MCV monofilament (single filament deployed) and the AH (25.9 +/- 10.9) and the MCV mono + passive filaments (both filaments deployed, one connected) and the AH (19.9 +/- 11.4); 24% DFT reduction P = 0.008. A bystander electrode adjacent to a monofilament electrode in the MCV reduces DFT by 24% when compared with monofilament MCV alone. Microfilament electrodes decrease DFT as auxiliary anode but not as sole anode.

Use of Auxiliary Electrode to Prevent Alkalinization of Soil in Electrokinetic Remediation

We devised an improved electrokinetic remediation method in which an auxiliary electrode was placed at the cathode-side end of the soil to be treated. The electric potential difference between the anode and the auxiliary electrode was fixed constant while that between the cathode and the auxiliary electrode was controlled to make the auxiliary electrode function as a secondary anode. To test the performance of the method, we carried out a bench scale remediation experiment on cadmium-contaminated soil, in which the electrodes and soil etc. were. arranged in the following order; anodelanolytelsoil-auxiliary electrodelelectrolytic diaphragmlH-saturated cation exchange resinlcatholyielcathode. During 1 12 h of the treatment, the net voltage applied to the soil could be maintained and the alkalinization of the soil could be prevented partly due to the acid-neutralization in the cation exchange resin, and partly due to the secondary anode. These results indicated the auxiliary anode was effective to improve the efficiency of electrokinetic remediation of heavy metals contaminated soils.

Examination of a middle cardiac vein defibrillation coil as stand-alone anode, auxiliary anode, and bystander electrode in a transvenous defibrillation circuit.

In porcine studies anodes in the middle cardiac vein compare favorably with those in the RV. It has not been demonstrated whether the RV and middle cardiac vein or the middle cardiac vein alone anodes are superior when shocking to a conventional SVC and active housing cathode nor whether a bystander middle cardiac vein electrode exerts a passive electrode affect. Twelve pigs were anesthetized and had an active housing implanted in the left pectoral region and defibrillation coils placed at the RV apex and in the SVC. A custom-made defibrillation coil (Ela Medical) was advanced into the middle cardiac vein through a 9 Fr transvenous catheter. The DFT for three anodes (RV; RV and middle cardiac vein; middle cardiac vein) to the SVC and active housing was then assessed by a three reversal binary search, the order of testing was randomized. In seven animals DFT was assessed in the same way for the configuration of RV to SVC and active housing twice more, with and without a bystander middle cardiac vein coil electrode in place. The results were middle cardiac vein 7.5 +/- 1.7 J, RV and middle cardiac vein 7.3 +/- 1.7 J reduced DFT significantly compared to RV 13.8 +/- 4.2 J (both P < 0.000). There was no significant difference between the middle cardiac vein and the middle cardiac vein and RV (P = 0.67, 95% CI for difference -0.64-0.96). The DFT of RV to SVC and the active housing was the same with (13.2 +/- 4.0) and without (13.7 +/- 4.2) the middle cardiac vein bystander coil in place (P = 0.177, 95% CI for difference -0.33-1.33 J). Shocking to a SVC and active housing cathode, middle cardiac vein, and RV and middle cardiac vein anodes are equally effective in lowering DFT compared to the RV. The middle cardiac vein coil electrode does not exert a passive electrode affect on the RV to the SVC and active housing defibrillation.

Increase in the Charge State of the Uranium Ion Beam Generated by the MEVVA Ion Source

The Metal Vapor Vacuum Arc (MEVVA) ion source and its modifications are investigated at the Institute of Theoretical and Experimental Physics (ITEP). In a series of the experiments, the possibility of increasing the charge state of the generated uranium ion beam was revealed. The charge state increases as a result of developing a high-current vapor vacuum arc discharge from the source cathode to an auxiliary anode located in an increasing axial magnetic field. The uranium ion beam with a total current of 150 mA was obtained, U7+ uranium ions being 10% of the current.

Basic investigations of an integrated modulator for plasma immersion ion implantation

The replacement of an external high voltage modulator by an integrated plasma based modulator, would considerably reduce the costs of plasma immersion ion implantation equipment. An inherent restriction of the integrated modulator is the limited maximum current. In order to overcome this limitation, detailed investigations are presented on the response of the plasma if electrons are extracted by a large auxiliary anode with special emphasis on the processes near the wall and near the control grid of the modulator. An anode potential of 20 kV results in an increase of the plasma floating potential from −8 V to approximately 60 V, as revealed by probe measurements, so that all electrons leaving the plasma are collected by the anode. Simultaneously a two- to threefold increase of the plasma density is observed.

Effects of high-flux low-energy ion bombardment on the low-temperature growth morphology of TiN(001) epitaxial layers

Ultrahigh vacuum scanning tunneling microscopy (STM) is used to characterize the surface morphology of TiN(001) epitaxial layers grown by dc reactive magnetron sputtering at growth temperatures of T{sub s}=650 and T{sub s}=750 degree sign C. An auxiliary anode is used to bias the N{sub 2} plasma and produce a large flux of low-energy N{sub 2}{sup +} ions that bombard the film surface during growth: the ratio of the N{sub 2}{sup +} flux to the Ti growth flux is {approx_equal}25. At ion energies E{sub i} near the threshold for the production of bulk defects (E{sub i}=43 eV and T{sub s}=650 degree sign C), ion bombardment decreases the amplitude of the roughness, decreases the average distance between growth mounds, and reduces the sharpness of grooves between growth mounds. The critical island radius for second layer nucleation R{sub c} is approximately 12 and 17 nm at growth temperatures of 650 and 750 degree sign C respectively; at 650 degree sign C, R{sub c} is reduced to (approx =)10 nm by ion bombardment. (c) 2000 The American Physical Society.

An efficient DC‐PDP cell structure with a wall cathode and wall auxiliary anode

Abstract— A new cell structure for a monochrome DC‐PDP with a wall cathode and a wall auxiliary anode is suggested. The wall cathode has a sufficient discharge‐electrode area to allow maximization of the discharge volume. The wall auxiliary anode surrounds the discharge region, which can effectively control the charged particles in the discharge region. We investigated the characteristics of the new cell structure with a two‐dimensional computer simulation and with experiments on a test panel and compared them with those of an earlier cell structure which has a co‐planar anode and an auxiliary anode. Special emphasis was given to the effect of the wall auxiliary anode on the discharge characteristics. The new cell structure shows high luminance and improved discharge characteristics such as a short discharge build‐up time and decreased minimum sustain voltage. The wall auxiliary anode plays the same role as in the coplanar‐anode‐type structure, but it demonstrates a better performance.

Some problems in the manufacturing of an electro-deposited diamond wheel

“Variation” is a phenomenon in which an electro-deposited layer thickness is not uniform on a surface, and is an undisirable phenomenon for a formed wheel. In this paper, the mechanism for the occurrence of variation and the effect of an auxiliary anode and cathode on the prevention of variation are made clear.

Deposition of hard coatings in open magnetic field confined plasma

A d.c. glow discharge deposition system is described which allows the independent control of the substrate current density by using several discharge power supplies. The system consists of a magnetron cathode with permanent magnets and a magnetic coil placed behind the magnetron target, three cages with permanent magnets and an auxiliary anode parallel to the magnetron target surface. The magnetron cathode, auxiliary anode and magnetic cages enclose the deposition volume in which the substrates to be treated are placed. An open geometry magnetic field is obtained in the deposition volume by suitable arrangement of the permanent magnets. The main gas discharge in the system is a balanced magnetron discharge obtained by means of a 20 kW power supply. Three additional power supplies are used to unbalance the magnetron magnetic field by adjusting the magnetic coil current, to bias the substrate and to change the potential of the auxiliary anode. The performance of the deposition system was tested during reactive deposition of TiN coatings on HSS steel substrates.

Numerical analysis of the microdischarge in a DC plasma display panel by 2-dimensional multifluid equations

A numerical analysis of the microdischarge in a plasma display panel have been made by using 2-dimensional multifluid equations. The discharge gas used is Ne+Ar 0.1% in a state of non-LTE glow. The distributions of the microscopic variables such as the density, temperature, velocity of the charged particles and the density of the uncharged particles are obtained. The distributions of excited species are examined during glow and afterglow. From the simulation results, the nondischarge pulses applied to the auxiliary anode confine the plasma to the core of the microdischarge. It is found that metastable species and other excited species are locally confined around the auxiliary anode during glow and afterglow. Locally confined particles indirectly due to the nondischarge pulses play a role to improve the characteristics of the DC plasma display panel. >

Evaluating the Effect of Auxiliary Anodes on Coating Thickness Distribution in Eelectrodeposition Cells using a Probabilistic Method

SummaryThe probabilistic method of determining coating thickness distribution in electrodeposition cells is theoretically extended to deal with the introduction of auxiliary anodes. Equations are derived that enable cathode current distribution to be determined when the auxiliary anode potential is the same as that of the main anode and also when its potential is set to a different value. Computer simulations are carried out to examine the effect of auxiliary anode potential and position when electrodepositing into recesses and onto peaks, and to determine optimum configurations. The computed results obtained are corrected for current efficiency variation with current density and compared to experimentally obtained thickness distributions o f chromium deposits.