Extraction Electrode Research Articles

Efficiency investigation of a negative hydrogen ion beam production with the use of the gasdynamic ECR plasma source

Negative hydrogen ion sources are of great demand in modern physics as injectors into accelerators and drivers for neutral beam injectors for fusion devices. It has been shown earlier that the use of the gasdynamic ECR discharge provides the opportunity to extract up to 80 mA/cm2 of negative ion current density. We studied experimentally the volumetric negative hydrogen ion production and vacuum ultraviolet emission in a gasdynamic ECR discharge. The high-density plasma was sustained by the pulsed 37 GHz / 100 kW gyrotron radiation in a magnetic configuration consisting of two consecutive simple mirror traps. The future prospects of the volumetric H− source based on the gasdynamic ECR discharge related to the transition from pulsed to continuous operating mode with the use of an improved magnetic confinement system are discussed. Numerical simulation of the negative hydrogen ion beam extraction at the continuous operating mode facility was performed. Optimal configuration of the extraction electrodes and the electron damping magnets was found.

The self-induced electric-field-driven jet printing for fabricating ultrafine silver grid transparent electrode

ABSTRACT To overcome the mandatory requirement of nozzle conductivity in the conventional electrohydrodynamic (EHD) jet printing, this paper proposed a self-induced electric-field-driven jet printing for fabricating ultrafine silver grids. In this method, only a copper foil is mounted on an insulating glass nozzle to serve as an extraction electrode for producing an electric field with substrate by electrostatic induction, which not only saves the fabrication cost of conduction treatment, but also reduces the amount of residual charges to improve printing stability. The simulation and experimental results have confirmed printing ability and optimised the printing parameters. Based on the optimised parameters and high viscosity silver paste, silver grids with line width (300 nm–7 μm) and aspect-ratio (0.39–1) have been printed successfully. Finally, silver grids with line width of 3.5 μm and a pitch of 90 μm were successfully fabricated with excellent performance of transmittance (T = 92%) and sheet resistance (Rs = 1.3429 Ω sq−1).

High-Resolution Ion Microscope Imaging over Wide Mass Ranges Using Electrodynamic Postextraction Differential Acceleration.

A time-dependent postextraction differential acceleration (PEDA) potential was used to temporally focus increasingly heavy ions in a stigmatic imaging mass spectrometer, allowing them to be imaged with high mass and spatial resolutions over a broad mass-to-charge (m/z) range. By applying a linearly rising potential to the ion extraction electrode, sequential m/z ratios were subjected to a changing electric field, allowing their foci to coincide at the detector. Using this approach, at least 75% of the maximum mass resolution was obtained over a 300–600 Da range when the ion microscope was focused around 450 Da, representing more than a 10-fold increase over the conventional single-field PEDA method.

Lithium Extraction from Seawater through Pulsed Electrochemical Intercalation

Summary It is highly attractive to develop efficient methods to directly extract Li from seawater to secure the supply of Li. However, high concentration of Na in the seawater poses a great challenge in Li extraction. Here, we developed pulsed-rest and pulse-rest-reverse pulse-rest electrochemical intercalation methods with TiO2-coated FePO4 electrodes for Li extraction. The method can lower the intercalation overpotential and successfully boost the Li selectivity. Moreover, the pulse-rest-reverse pulse-rest method can also promote electrode crystal structure stability during the co-intercalation of Li and Na and prolong the lifetime of the electrode. We demonstrated 10 cycles of successful and stable Li extraction with 1:1 of Li to Na recovery from authentic seawater, which is equivalent to the selectivity of ∼1.8 × 104. Also, with lake water of higher initial Li/Na ratio of 1.6 × 10−3, we achieved Li extraction with more than 50:1 of Li to Na recovery.

Simulation of Penning ion source with optimized beam extraction system for tagged neutron tube

The magnetic field structure of the Penning ion source has been optimized with the use of permanent magnets. The ion source has been designed for small sealed tagged neutron tube. By using CST Studio Suite, the magnetic field profile inside the ion source was simulated and a variety of magnetic system was designed to improve the magnetic field uniformity of the Penning ion source and to increase the neutron yield. And the simulation results were compared with the experimental data to verify the correctness of the model. A new type of ion focusing system was devised by using the characteristics of conducting magnetic and consolidating magnetic of different metallic materials. There is more uniform magnetic field distribution and less material for the structure of 6-ring magnets placed outer anode than the structure of cylindrical magnet below the cathode. Stainless steel is selected as the material of the new extraction system after comparing the magnetic relative permeability of several materials. The new system has obvious focusing effect on the ion beam. It is also easy to obtain a small beam spot with 1 mm radius suitable for the tagged neutron tube and the extraction electrode voltage gets lower than original voltage. The results can provide reference for the improvement of the tagged neutron tube.

Design and simulation of the parameters affecting the ion beam characteristics from a penning ion source

Today, many different kinds of ion sources have been developed. One of the most important ones is the penning or PIG ion source. Due to its simplicity of structure and longer lifetime, these ion sources are more widely considered than other ones. In this paper, design and simulation of the parameters affecting the ion beam characteristics from a penning ion source are performed using the CST software. Among the various structures of the permanent magnet around the source, the circular arrangement is found to be better for the confinement of particles inside the source. The electric potential of the anode, the cathode and the extraction electrode are found to be 15+, -500 and -3000 Volt, respectively. The decelerator and accelerator electrodes are used as ion source extraction systems. In addition, in the beam transport systems, high efficiency focusing in Einzel lens is more than that of immersion lens.

Increase of the particle hit rate in a laser single-particle mass spectrometer by pulse delayed extraction technology

Abstract. A single-particle mass spectrometer (SPMS) can provide a wealth of valuable information on chemical and physical parameters of individual particles in real time. One of the main performance criteria of the instrument is efficiency of particle detection (hit rate). Most SPMS instruments use constant electrical field (DC) extraction, where stationary high voltage is applied to the extraction electrodes. As the aerosol particles initially carry a certain charge, those with a high amount to charge can be deflected by this electric field and lost, thus decreasing the hit rate. We realized that the delayed extraction technique can eliminate the stochastic dispersion of the particle beam caused by their deflection in the stationary electric field. As the result, the hit rate of the instrument can be significantly improved. Also, as the effect of the deflection in the electric field is mass dependent, it can cause distortion of the measured size distribution of the particles. Hence, the delayed extraction technique can bring the recorded distribution closer to the actual one. We found that the delayed extraction technique provides a mass resolution improvement as well as increases the hit rate. The gain in the hit rate depends on the type of particles. It can be 2 orders of magnitude for model particles and up to 2–4 times for ambient particles. In the present work we report experiments and results showing the effect of the delayed extraction on the beam divergence caused by particle charge, the hit rate improvement, and the effect of the delayed extraction on the measured particle size distribution.

Experimental Investigation of Ion Beam Extraction in Filament-Driven Negative-Carbon-Ion Sources With Various Geometrical Configurations for Accelerator Mass Spectrometry

A negative carbon-ion source was designed for accelerator mass spectrometry for application in the medical field to minimize cross-contamination and to increase the measurement efficiency. The ion source was designed by adjusting the distance between the plasma and the extraction electrodes and by changing the anode structure. Various prototype ion source configurations were fabricated to construct an ion source test stand to confirm the carbon beam extraction. The transport efficiency of the negative carbon beam was experimentally investigated using a filament-driven ion source to determine the geometrical effect of the anode configuration. The carbon-ion source was operated under carbon dioxide gas flowing at 3.0 sccm at a high voltage of −30.0 kV and an applied arc current of up to 0.5 A and various magnetic fields. The optimized anode structure and operating conditions of the ion source with the beam characteristics must be verified to measure the beam current with various ion source parameters. The effects of various operating and structural conditions on the beam current are evaluated in this article.

ПОЛІПРОПІЛЕНОВИЙ БІПОЛЯРНИЙ ЕЛЕКТРОД ДЛЯ ЕЛЕКТРОЕКСТРАКЦІЇ КОБАЛЬТУ

In the article the polypropylene bipolar electrode is offered for the cobalt extraction from low concentration solutions. Research object: electrolyzer with polypropylene bipolar electrode. Purpose of the study: research of cobalt electroextracton on the polypropylene bipolar electrode from low concentrated solutions. Research methods: stationary and non-stationary voltamperometry. measuring method of micro hardness. It was established that application of bipolar electrolyzer provides high purity electro-extraction of metal in the process of cobalt extraction. Using of polypropylene bipolar electrode provides lightness and plasticity that is not realized in the case of similar metallic. Received fallouts have a microhardness from 350 to 450 kg/мм2, depending on ions concentration of metal in electrolyte. Fallouts with maximal microhardness - homogeneous, fine crystalline with narrow distribution after the sizes of 5 - 8 mkm. The maximal values of extraction coefficient and current output from diluted solutions of their salts set 74 аЫ 76 % (respectively) at the rate of bipolar movement 1,5 спі/miin For an extraction 1 kg of cobalt it is necessary 20 kW4i, the process is effective and does not require high energy costs. The results of the article can be implemented in technology of wastewater treatment from heavy metal ions at galvanic productions. In the future it is planned to study the possibility of application polypropylene bipolar electrode for metal extraction. KEY WORDS: POLYPROPYLENE BIPOLAR ELECTRODE, COBALT ELECTOEXTRACTION, LOW CONCENTRATION SOLUTIONS.

Electrochemical characterization of the liquid aluminium bipolar electrode for extraction of noble metals from spent catalysts

Regularities of the cathodic and the anodic behaviour of aluminium on tungsten in halide melts are investigated. The study of such systems is relevant in connection with the prospects for their use as bipolar electrodes for efficient extraction of noble metals from spent petrochemical Al2O3-based catalysts by the electrometallurgical method with associated production of high-purity aluminium and oxygen. Stationary and non-stationary polarization curves were obtained for the reduction and the oxidation of aluminium in molten NaCl – KCl + 5 wt.%AlF3 and 1.3KF – AlF3 systems at 700–850 oC (973–1123 K) in the range of current densities from 0.01 to 1.5 A·cm–2 and in the range of potential sweep rates from 0.01 to 5 V·s–1. Electrochemical characterization of the electrode showed that electroactive particles in chloride-based melts have higher diffusion coefficients (in comparison with fluoride melt) due to the high concentration of Na(I) and K(I) cations, low density and viscosity of the melt. Electrochemical dissolution and reduction of aluminium in both chloride-based and fluoride melts are quasi-reversible diffusion-controlled processes complicated by several parallel phenomena. Cathodic reduction of Al(III) in both studied melts occurs at high overvoltages (more than 200 mV at 0.1 A·cm–2) with the limiting current densities of 0.3–0.4 A·cm–2 at 800 oC. The cathodic reduction of Na(I) starts in chloride-based melts at the potential of –0.5 – (–0.7) V relative to Al reference electrode; the reduction of K(I) in both studied melts starts at –1.0 – (–1.2) V. In general, the kinetic parameters of the processes show that the extraction in two-sectioned cell can be beneficially performed at 800 oC with high current densities, and the liquid aluminium bipolar electrode seems to be the promising solution.

Investigation of the electrostatic focusing of beams of electrosprayed nanodroplets for microfabrication applications

This article presents a focused electrospray beam source and discusses its potential for microfabrication. Its main elements are an electrospray emitter electrode (a point source of charged nanodroplets), an extractor electrode, a skimmer electrode, and an Einzel electrostatic lens. The focusing parameters of the source are calculated by integrating the equations of motion of the charged droplets in the axisymmetric electrostatic field generated by the electrodes. The results of the model are validated with a laboratory source replica by characterizing the sputtered region produced by the focused beam on a silicon target and comparing it with the image obtained with the model. In the experiments, the size of the focused beam at the image plane is at least 20 times smaller than that of the unfocused beam, despite the presence of aberrations that have a negative effect on the ability to concentrate the beam. In a well aligned source, the sputtered area is close to a disk, and spherical and chromatic aberrations are the most significant nonidealities making the size of the image larger than the ideal one. When the emitter is deliberately misaligned, spherical and chromatic aberrations continue increasing the size of the image, while astigmatism distorts its circular shape. All aberrations are reduced by increasing the strength of the focusing electrostatic field while maintaining the net acceleration potential of the beam. The focusing column increases the particle density of the beam and advances the development of electrosprayed nanodroplet beams as a tool for surface engineering.

Piezoelectric P(VDF-TrFE) micro cantilevers and beams for low frequency vibration sensors and energy harvesters

Piezoelectric P(VDF-TrFE) micro-cantilevers and beams have been developed with a novel micro-electromechanical systems process very useful for low frequency vibration sensors and energy harvesters. The devices were designed and simulated using COMSOL Multiphysics simulation software to determine the resonant frequency, voltage and power output for various dimensions with length in the range 200 μm to 2000 μm, width in the range 100 μm to 400 μm and thickness 2.5 μm in all cases. Devices were fabricated on <110> silicon wafers using a novel bulk micromachining process by suspending them using critical process steps which include: micromachining of silicon substrate from the backside using anisotropic wet etchant TMAH to define the device suspension regions with thin SiO2 diaphragm, and release of micro-cantilevers and beams by etching the SiO2 diaphragm from backside with CHF3/O2 based plasma etching. All the devices were fabricated with 2.5 μm P(VDF-TrFE) spin coated on SiO2. Laser Doppler Vibrometer was used to measure resonant frequency, voltage and power output of the devices which were operated in longitudinal mode with thermally evaporated Cr-Au interdigitated electrodes for power extraction. The experimental results obtained on fabricated devices for the first time using this process were in good agreement with those derived from simulation.

Annealing provoked modification of ZnPc photoactive nanolayer via self-assembling at SnO2 hybrid interface and its effect on layer electric properties towards application in hybrid photovoltaic devices

Best-performing organic photovoltaic devices rely on nanostructured active layer morphology to have better hole-electron separation and their extraction from the active layer to respective extraction electrode. Although much progress has been made in designing new organic molecules, rational control over active layer morphology remains a central challenge. In this article, we have presented a control means to improve the morphology of active layer and the degree of carrier transportation from the active layer ZnPc to Electron Transportation Layer (ETL) SnO2 using variable self-assembly behavior of ZnPc molecules with assistance of annealing. Post processed annealed sample at 290 °C shows better photo response compared to as-deposited sample. Structural and electrical studies supports the formation of columnar shape nanostructures in the active layer on annealing results in better hole-electron separation at the interface with ETL favored by better extraction of charge carrier to their respective electrode. Annealing resulted in enhancement of mobility from 1 × 10−7 m2 V−1 s−1 for as-deposited sample to 1.7 × 10−6 m2 V−1 s−1 for 290 °C annealed sample with corresponding reduction of trap concentration from 3.6 × 1026 m−3 to 2.0 × 1026 m−3 because of ordered molecular stacking of ZnPc molecules into columnar shape nanostructure favored by heat treatment.

Fabrication of a high-density emitter array for electrospray thrusters using field emitter array process

To improve the thrust density of electrospray thrusters using ionic liquids as the propellant, we have fabricated a high-density emitter array utilizing the fabrication technique of a field emitter array (FEA) or gated nano electron sources. The density of the emitter array can reach approximately 4 million cm−2, which is four orders of magnitude higher than that of conventional electrospray thrusters. Performing deep reactive ion etching from the back side of the same structure as FEAs and removing their Ni cones by dilute nitric acid, we have successfully fabricated sub-μm scale capillary emitters with self-aligned extractor electrodes and ionic liquid reservoirs behind them. Current measurements were also conducted with EMI-BF4 and EMI-DCA as the propellant. Although the ion was not extracted with EMI-BF4 owing to its electrochemical reaction with the electrodes, both positive and negative ion currents were detected using EMI-DCA, where the current density exceeded that of conventional electrospray thrusters.

Generation of Supersonic Plasma Flow by an Ion Extraction Electrode

A concept of ion extraction has been adopted to generate and analyze supersonic plasma flow (M∞ > 1) in steady state condition. A capacitively coupled plasma (CCP) with weakly magnetic intensity (B = 100 G) was used as a plasma source along the axial direction and a cylindrical electrode was installed to generate negative potential within plasma by depleting ions. Characteristics of ion velocity distribution have been analyzed by equation of energy conservation from depletion ratio of ions within an ion extraction electrode. The normalized velocity (M∞ = vi/Cs) of flowing plasmas was deduced by using a Mach probe (MP) of parallel type using an exponential formula of the ratio of upstream and downstream ion saturation current densities. The first result on the measurement of ion velocity distribution with supersonic plasma flow (M∞ =~ 1.1–1.2) is obtained.

The effect of gate mesh electrode strain on performance of cold cathode electron beam

The effect of an electron extraction electrode on electron emission was studied, in particular, the effect of the strain of a gate electrode for high-performance cold cathode electron beam fabrication. For the cold cathode electron beam with carbon nanotube emitters, the structure of a gate grid mesh electrode was one of the most important components. Gate current through the grid mesh was a serious hurdle to be overcome. When gate current is high, the electron emission current could be saturated, even if the gate bias is increased. To overcome this phenomenon, the structure of the gate electrode was optimized. By using a lower strain gate mesh structure with low-cost SUS304 material, we could reduce the gate current ratio from 17% to 8.4%. Finally, we could increase the electron emission current from 0.6 to 2.3 mA and current density from 40 to 202 mA cm−2, with a gate mesh with 77 μm strain in 1.5 N weight load.

Extraction of positive and negative ion beams from large area plasma sources

In this study we investigate extraction and acceleration of positive and negative ions from a pulsed inductively coupled plasma (ICP) in oxygen and hydrogen. Experiments were performed in a directed ribbon beam system where ions can be produced at an incident angle non-normal to the target. Positive and negative ions were transported to the wafer. The RF plasma source, extraction electrodes and wafer were biased synchronously. The energy of extracted ions closely follows the amplitude of the applied bias voltage and it ranges from few hundreds of volts to 10 kV. The peak beam current density can reach 100 A m−2. The ion beam angles, ion current, and ion composition are reported. The injection physics requires correlating the positive and negative ion and electron densities near the extraction opening with the extracted currents. The plasma was modeled using CRTRS, a plasma fluid code that self-consistently solves for ICP power deposition, electrostatic potential, and plasma dynamics. A new perspective on the possible production of angled ion beams on surfaces is discussed.

Effective parameter in extraction of ion-beam from a diode system

The effects of the gap distance between the electrodes and the extraction voltage on the spot, shape and the kinetic energy distribution of the argon ions were studied theoretically for a diode extraction system. The results showed that under specific conditions, a good focusing to ion- beam was found, where the dimensions of the ion spot were reduced by about 28.6% at gap distance 8 mm and extraction voltage -35 kV with best controlled for hitting ion to the extraction electrode. Also, a homogenous kinetic energy distribution of the beam can be found at distance between 10 mm and 25 mm.

Electrospray ionization source with a rear extractor.

A new electrospray source design is introduced by having an extractor electrode placed at 1 to 2mm behind the emitter tip. The extractor was integrated into the sprayer body as a single device. An insulating tube was used to isolate the emitter from the extractor and to deliver the sheath gas for the electrospray. The electric field strength at the emitter was primarily determined by the relative position and the potential between the needle and the extractor; therefore, the spraying condition was insusceptible to the change of sprayer position or orientation with respect to the ion sampling inlet. Such design allowed the use of much lower operating voltage and facilitated the optimization of sprayer position by keeping the electric field parameter constant. Using an emitter capillary of 150 and 310μm in inner and outer diameters, strong ion signal could still be acquired with 2-kV emitter potential even if the distance between the emitter and ion inlet was extended to >70mm. Charge reduction of protein ions using 2 extractor-based electrosprays of opposite emitter polarities was also demonstrated.

Monolithic FFF-Printed, Biocompatible, Biodegradable, Dielectric-Conductive Microsystems

We report additively manufactured biodegradable microsystems composed of dielectric and electrically conductive layers. The devices were made via fused filament fabrication (FFF), which is arguably the simplest and cheapest commercial 3-D printing technology, done with the most inexpensive printing hardware. The base constitutive material is polylactic acid (PLA)–a biodegradable polymer made of cornstarch that can be doped with micro and nanoparticles to change its physical properties, e.g., become electrically conductive. The devices were monolithically manufactured using a commercial dual extruder 3-D-printer. The feature resolution and surface topography of the printing technology was characterized for both dielectric and conductive materials; their outgassing rates were measured and their cytotoxicity was investigated. The gauge factor of the conductive PLA was measured. Basic electrical components, cantilevers, and electrohydrodynamic liquid ionizers with integrated extractor electrode and threaded microfluidic port were demonstrated. [2017-0118]