Positive Hydrogen Ions Research Articles

Overview of neutral beam injectors for plasma heating and diagnostics developed at Budker INP

An overview of the neutral beam injectors developed at the Budker Institute of Nuclear Physics in Novosibirsk during the last 10 years is presented. These neutral injectors are used for plasma diagnostics, heating and current drive in modern fusion devices with magnetic confinement. An arc or a radio-frequency (RF) discharge generates a plasma in the ion sources of the injectors, and a positive hydrogen or deuterium ion beam is extracted and accelerated by a multiaperture ion-optical system (IOS). The accelerated ion beam is converted into a neutral one in a gas target. The precision multiaperture IOS with spherically concave electrodes provides ballistic focusing of the neutral beam. The high-energy, high-power beam injector based on negative ions, which is currently under development, is described as well. It comprises a RF negative ion source and a wide-aperture electrostatic accelerator separated from the source by a low-energy beam transport line, thereby improving the injector reliability.

More Than Marine Heatwaves: A New Regime of Heat, Acidity, and Low Oxygen Compound Extreme Events in the Gulf of Alaska

AbstractRecent marine heatwaves in the Gulf of Alaska have had devastating impacts on species from various trophic levels. Due to climate change, total heat exposure in the upper ocean has become longer, more intense, more frequent, and more likely to happen at the same time as other environmental extremes. The combination of multiple environmental extremes can exacerbate the response of sensitive marine organisms. Our hindcast simulation provides the first indication that more than 20% of the bottom water of the Gulf of Alaska continental shelf was exposed to quadruple heat, positive hydrogen ion concentration [H+], negative aragonite saturation state (Ωarag), and negative oxygen concentration [O2] compound extreme events during the 2018–2020 marine heat wave. Natural intrusion of deep and acidified water combined with the marine heat wave triggered the first occurrence of these events in 2019. During the 2013–2016 marine heat wave, surface waters were already exposed to widespread marine heat and positive [H+] compound extreme events due to the temperature effect on the [H+]. We introduce a new Gulf of Alaska Downwelling Index (GOADI) with short‐term predictive skill, which can serve as indicator of past and near‐future positive [H+], negative Ωarag, and negative [O2] compound extreme events near the shelf seafloor. Our results suggest that the marine heat waves may have not been the sole environmental stressor that led to the observed ecosystem impacts and warrant a closer look at existing in situ inorganic carbon and other environmental data in combination with biological observations and model output.

Development and commissioning of a hydrogen ion source for the CERN ALPHA experiment

The CERN ALPHA experiment makes precision measurements of antihydrogen atoms held in a superconducting magnetic minimum trap. Recent studies of the antihydrogen spectrum have provided unique tests of fundamental physics, and to improve on these studies ALPHA is now proposing upgrades to directly compare hydrogen and antihydrogen within their existing atom trap. One route towards producing cold, neutral hydrogen atoms is the integration of a hydrogen ion source into the experiment. Ideally, this should provide both positive (H+, H2 +, H3 +) and negative (H-) ions to facilitate different schemes for producing and trapping hydrogen atoms. For compatibility with ALPHA's existing beamlines, the source must produce modest (∼ 10 μA) beam currents at very low final energies (<100 eV). PELLIS, previously developed at JYFL, is a filament-driven ion source that generates 5–10 keV H- beams with small emittances and tens of microamps of beam current. Here, we present a modified PELLIS design to provide both positive and negative hydrogen ions for ALPHA. The use of an electromagnet filter field in PELLIS allows for the optimisation of H- volume production, and also tuning of the positive ion species fraction. We present simulations of H- (and similarly H+) transport through the initial extraction optics, which have been configured for a lower beam energy of 5 keV and designed to match a proposed beamline to interface with ALPHA. We present the results of detailed vacuum simulations that were used to guide the optics design, allowing the source (at 10-2 mbar) to interface with a transport beamline ∼ 0.5 m downstream that has strict vacuum requirements of < 10-9 mbar. We present experimental results from commissioning of the source, and show that it broadly performs as designed for both positive and negative hydrogen ions.

Constant current pulsed power supply for long pulse arc discharge positive hydrogen ion source.

The simplest way to produce high density hydrogen plasmas is to form an arc between the arcing electrode and the plasma chamber (cathode). For arc-based hydrogen plasma generation, a pulsed power supply that delivers 2 ms-long constant current pulse has been developed. This pulsed power supply employs a high frequency buck converter topology with a nonlinear filter inductor. This paper describes the development and testing of a constant current pulsed power supply that operates at 50A and 550V with a pulse width of 2ms and a pulse repetition rate of 2Hz. By changing the arc current, the arc impedance and the positive hydrogen ion current were also measured. The extraction of positive hydrogen ions was carried out using a three-electrode extraction design, which results in a current of 80 mA of positive hydrogen ions at an energy of 50keV.

Design and optimization of an adjustable RF positive hydrogen ion source

An adjustable radio frequency (RF) positive hydrogen ion source is designed in Huazhong University of Science and Technology (HUST) to provide ion beam with adaptive beam current and beam energy for neutral beam injection (NBI) related material research. The ion source aims to produce 10–20 keV positive hydrogen ion beam with total current of 50–125 mA. This paper investigates the design of the RF ion source including RF driver via inductively discharge mechanism and the extractor which is designed and optimized, including ion beam optics simulation, thermal analysis and power supply analysis. The vacuum analysis of the source is carried out as well.

Design and simulation of the high efficiency ion source for Damavand NBI heating system

Neutral beam injection (NBI) is known as one of the important methods of plasma auxiliary heating and current drive in fusion reactors. Optimization of the ion sources, as one of the main components of NBI systems, with high current and minimum divergence, can be very effective in order to reach more optimal dimensions of NBI systems. A high efficiency ion source designed using a helicon plasma source for neutral beam injection system (NBI) of Damavand Tokamak. The extraction system has the ability to extract a positive hydrogen ion beam with the current and voltage of 7A and 4.5 kV, respectively. In this paper, an ion source with optimized helicon plasma and optimized beam extraction system is developed using the COMSOL software. All parameters, including RF power, magnetic field, gas pressure, antenna length, and RF frequency, for the production of helicon plasma and ion beam extraction system with optimal geometry are investigated in the most effective way, in order to reduce the beam divergence and beam current increment. Finally, the helicon plasma with density of 4.12×1018m−3, electron temperature of 2.8eV and hydrogen beam extraction system consists of three Accel-Decel grid, each grid with 280 apertures of 3.5mm diameter, has been designed for neutral beam injection system of Damavand Tokamak. This ion production system has an extractor grid with very large transparency (60%) and the minimum single beamlet divergence of 27 mrad.

Modeling and Validation of the Micro Photosynthetic Power Cell Harvesting from Blue Green Algae

Introduction: The ever-growing need for energy is becoming an inevitable concern in today’s life. Amongst various source of new energy sources and more specifically energy harvesting systems, the biological-base energy harvesters have been attracting attentions within the past few years. Utilization of photosynthetic microorganisms as the heart of energy harvesting system is a new technology which is still under development and study. Micro photosynthetic power cell (mPSC) is one such system that works based on harvesting electricity from the photosynthesis of living microalgae culture which has been under study for several years[1].There are several advantages in implementing mPSC over other conventional energy harvesting systems including photovoltaic power cell and this is due their nature of operation. mPSC technology is cleaner than many other energy harvesting systems as it uses biological organisms as the main source of energy. Moreover, mPSC can operate in both light and dark conditions which makes it a reliable source for low-power applications and sensors that requires continuous power supply. Due to the newness of this technology, the development and optimization of these systems are still in research. Principle of Operation: Micro photosynthetic power cell (uPSC) is an electrochemical cell that produces electricity at micro scale. During the light condition, a living microorganism culture use light to consume carbon dioxide and water to produce electricity and during dark condition, the produced glucose, disintegrates with the help of oxygen and as a result, the electrical power will be generated[2].Figure 1 provides a general schematic of the operation of uPSC. Same as the regular fuel cells, mPSC consists of two chambers known as anode and cathode chambers which are separated with a proton exchange membrane (PEM). PEM is responsible for letting positive hydrogen ions, more specifically protons to pass through itself from anode side to cathode side. On both sides of the membrane, porous electrodes have been placed to collect electrons from anode and release them in cathode chamberIn anode chamber, microorganisms which in this research is living microalgae culture perform photosynthesis in which during a complicated process, electrons and positive ions released. The released electrons near membrane surface then will be transferred to an external circuit for power generation. During the daytime, the cells do photosynthesis and in dark condition, they reverse the process also known as respiration and electrons will be released during both the processes.In the cathode side, the electrons will reduce the catholyte Potassium Ferricyanide to Potassium Ferrocyanide. In the same time, the transferred protons will oxidize back the reduced catholyte and with their combination with oxygen, water will be released. Methodology: This paper, discusses the simulation of the uPSC using COMSOL Multiphysics in a similar way as with the general fuel cell operating concepts. The geometry is provided in Figure 2. This simulation considers the electrochemical dynamics of the chemical species while considering the geometrical aspect of the uPSC device. The geometrical parameters have been obtained from the actual device that has been used for experimental purposes. The electrochemical parameters have been obtained from mathematical modelling on the same device[3]. The simulation is based on the reduction and oxidation of arbitrary species, concentration and mole fraction of the species and the respective number of transferred electrons within the electrochemical reactions. The simulation is capable of predicting the polarization curve and power curve of the uPSC in a time-independent domain considering the electrochemical kinetics and polarization losses including concentration, ohmic and activation losses. Results and discussion: In order to evaluate the performance of this simulation, the outputs have been compared with the experimental data at various configuration including different surface areas. In addition, the effect of internal resistance and temperature variation effect on the performance of the uPSC and the electrolyte potential gradient (Figure 3) has also been provided using the simulation. The results show good agreement between simulation and experimental results with the correlation coefficient of 0.9 and higher for different configuration of simulation and experimental data as provided in Figure 4.

THE POTENTIAL ENERGY OF GEL POLYMER ELECTROLYTES FROM GUPPY (Poecilia reticulata) FISH WASTE FOR BATTERY APPLICATION

This study aims to determine the potential energy of gel polymer electrolytes from guppy (Poecilia reticulata) fish waste for battery applications through different parameters. The parameters include the number of fish, the number of days, and the battery’s longevity. This experiment is underpinned by the concept of an electrical energy storage system of gel polymer electrolytes and urea as an energy carrier. The ammonia secreted by fish contains NH4+ which has positive hydrogen ion. The hydrogen ion in this element has the ability to produce electricity. This experiment involved tests on different batches of fish, with 5,10 and 15 fish in each respective batch. The wastewater samples were taken every two days, made into gel polymer electrolytes using agar, and inserted into the battery. The output voltage was recorded using a voltmeter, and each battery showed an increasing pattern of voltmeter reading against the number of days. For example, the highest voltage output was produced by a battery that used the wastewater sample with 15 fish on the 10th day, resulting in 0.45V. This is due to an increase of the amount of ammonia accumulated from fish waste within that 10 days. Batteries with the highest outputs of voltage from respective of number of fish were then taken for longevity test. The two weeks tests showed gradual decrease in the result due to many factors, including the ionic transference number and the disassociation of ionic particles in the electrolytes. The estimation of the battery longevity from water samples with 5, 10, and 15 fish were 71.47 days, 27.82 days and 34.44 days, respectively. This study proves that the gel polymer electrolytes from guppy, Poecilia reticulata has the potential to be used in batteries as an energy source.

Extraction of negative hydrogen ions produced with aluminum plasma grid

Negative hydrogen ions are produced and extracted using an aluminum plasma grid, without cesium through irradiation with hydrogen plasma. The negative ion amount increases sharply, up to ∼115 μA·cm−2, at a discharge power of 1 kW with an electric field downstream of the grid. These negative ions are extracted with high purity. In addition, it is suggested that negative ions are produced by positive hydrogen ions and hydrogen atoms. As high-density plasmas enhance the negative ion production, the current density of negative ions is expected to increase with plasma discharge power.

Commissioning and initial operation of the W7-X neutral beam injection heating system

Abstract The first, of two planned, neutral beam injectors for the stellarator Wendelstein 7-X (W7-X) was commissioned for and participated in the experimental campaign (OP1.2b) from July to October 2018. The injector was equipped with two RF driven ion sources from which 90A of positive hydrogen ions were extracted at 55 kV. After neutralization, the two sources provided >3 MW of neutral beam heating power to the stellarator plasma. During the experimental campaign >300 shots were successfully performed for plasma heating or to allow for measurement of the ion temperature profile by charge exchange recombination spectroscopy (CXRS). The initial operation of the NBI system on W7-X was very successful, demonstrating both increased central plasma density and stored plasma energy, or allowing for the collection of the time resolved ion temperature over the bulk of the plasma. This paper presents, briefly, source conditioning and performance, focusing on some of the initial problems encountered. Described in more detail is the most significant challenge overcome during commissioning: failure to couple RF power into one of the sources.

Contrast Experiments of Pig Positive and Negative Hydrogen Ion Sources for Neutron Tubes

Recent studies reported that PIG negative hydrogen ions extraction for neutron tube is superiority to positive hydrogen ions extraction. Present maturing products of neutron tube on market almost use PIG ion source and extract positive hydrogen ions. If negative hydrogen ions extraction can be applied on present products, the combination property will be greatly improved. In this study, a contrast experiment of PIG positive and negative hydrogen ion source for D–T neutron tube is put into effect. The relationships between the current of ion source, the beam current and the voltage extraction are investigated. The experiment results demonstrate that the negative ion extraction has higher yield of neutron for unit target current. We also point out that the ratio of yield to target current is a considerable parameter to reflect the overall performance of neutron tube.

Positive and negative hydrogen ion reflections of low-energy atomic and molecular hydrogen ion beam from HOPG and Mo surfaces.

Positive and negative hydrogen ion reflections from surfaces by injecting singly charged hydrogen ion beams show a clear difference between atomic and molecular ion injections at low energy and grazing incidence. The intensity ratio of reflected negative to positive ions H-/H+ increased as the incident beam energy per nucleon decreased only when molecular ion beams are injected. It implies that negative ions are more produced upon beam-surface interaction when molecules are injected. A possible reason was discussed in terms of difference in the negative ion production processes between atomic and molecular ions.

Design and comparison of the Cs ovens for the test facilities ELISE and SPIDER.

Negative ion sources for fusion rely on the formation of negative hydrogen (or deuterium) ions by conversion of atomic hydrogen and positive hydrogen ions at a low work function caesiated surface. Cs is thus evaporated into the source to decrease the surface work function, which may change due to the removal and redistribution of Cs during plasma phases. To maintain a temporarily stable low work function during 1 h plasma, continuous evaporation of caesium is required, and this is performed by temperature controlled Cs ovens. The Cs ovens for ELISE (IPP Garching) and SPIDER (Consorzio RFX) are based on the evaporation of liquid Cs from a reservoir located at one end of the oven, which is controlled by the reservoir temperature. The ampoule Cs oven of ELISE is in operation since 2015, allowing for controllable and stable evaporation. The SPIDER oven is based on the ELISE oven although it required significant changes due to the vacuum environment and the oven location (at the back-plate instead of the sidewalls), leading to a different design of the oven and the nozzle. First investigations on the SPIDER oven in a dedicated test stand show that Cs evaporation is controllable, stable, and reproducible.

The mechanism of negative and positive hydrogen ions production on the Ni surface

The studies about surface production of hydrogen negative ions play an important role in many technologies. In the present paper, a low energy molecular hydrogen ion beam was irradiated to the porous Ni sheet. It was found that negative atomic hydrogen ions were detected at the back of the porous Ni sheet when the energy of incident ion beam was lower than 180 eV. When the energy of the incident ions increased, the positive ions dominated at the back of the porous Ni sheet. The production of negative hydrogen on Ni surface can't be explained by comparing the electron affinity of Ni and H. The charge transferring during the process of H atoms reflected from Ni surface was calculated by using constrained DFT (cDFT). The results show the production of negative hydrogen on Ni surface may well be due to heterogeneous electron density on the Ni surface. However, the influence of incident energy on the production of negative and positive hydrogen ions is unable to be explained by cDFT. The problem may be solved by using TDDFT which is able to capture the transfer of energy to electrons during the collision between atoms.

Preparation of Cr2O3/Al2O3 bipolar oxides as hydrogen permeation barriers by selective oxide removal on SS and atomic layer deposition

Iron-nickel based stainless steel (SS) applied in nuclear plants as a substrate material barely suppresses the permeation of hydrogen plasmas, which are mainly composed of positive and negative hydrogen ions with trace amounts of non-ionized hydrogen atoms. In this work, a new Cr2O3/Al2O3 bipolar oxide barrier was prepared using atomic layer deposition (ALD) of Al2O3 on a Cr2O3 layer that was generated by removing partial oxides with cyclic voltammetry (CV) of SS that had been pre-oxidized at 550 °C in air. We found that a small layer of α-Al2O3 was formed by the template effect of Cr2O3 at the interface of this composite film. The hydrogen permeation behavior of this bipolar oxide barrier in a fusion reactor was simulated with hydrogen-discharging plasma treatment. The results demonstrated that the hydrogen permeation resistance of this bipolar oxide was superior to the original oxide or a Cr2O3 film. Impressively, hydrogen plasma treatment repaired the bipolar oxide via reduction of the defective CrO3, resulting in an improvement in the hydrogen permeation resistance. These findings demonstrate a novel method of hydrogen permeation barrier preparation on SS, providing insight into hydrogen barrier construction for future nuclear energy applications.

Energy distribution functions for ions from pulsed EUV-induced plasmas in low pressure N2-diluted H2 gas

The operation of Extreme Ultraviolet (EUV) lithography scanners inherently goes hand-in-hand with the creation of highly transient pulsed plasmas in the optical path of these tools. These so-called EUV-induced plasmas are created upon photoionization events when a pulsed beam of EUV photons travels through the low pressure background gas. It is fully recognized by the lithography industry that EUV-induced plasmas may significantly impact the quality and life-time of expensive and delicate optical elements in the scanner. Research efforts into EUV-induced plasmas impacting plasma-facing surfaces have so far been limited to pure hydrogen (H2) plasmas. However, this hydrogen background gas may occasionally be diluted with a small fraction of another molecular gas such as nitrogen (N2). The impact on the relevant plasma parameters of such molecular contaminants has remained unknown until now. In this letter, we put forward measurements of energy-resolved fluxes of (positive) hydrogen ions, nitrogen ions, and hydrogen-nitrogen ions created in a pulsed N2-diluted EUV-induced plasma in H2 at approximately 5 Pa (typical EUV lithography scanner conditions). The data have been obtained using an electrostatic quadrupole plasma analyzer and show that although the N2-dilution fraction is small (∼2 × 10−3) compared to the H2 partial pressure, implications for the ion flux out of the plasma and the composition thereof are significant. Since the mass of nitrogen-containing ions is much higher in comparison to that of their hydrogen counterparts, and because of their potential chemical activity, this effect has to be taken into account while studying the surface impact of EUV-induced plasmas.

Design features and commissioning of pulse arc plasma source and power supply system for the VEST neutral beam injection system

A short-pulse, high-power filament arc ion source is developed for the neutral beam injection (NBI) system of the Versatile Experiment Spherical Torus (VEST) device. The 0.6-MW NBI system is designed to deliver positive hydrogen ion beams at 20 keV for a pulse length >10 ms. In addition, the power supply system for the VEST NBI system is designed to change the beam injection energy during the pulse under VEST's initial target plasma parameters to increase beam–plasma coupling efficiency. To satisfy these requirements, a large-area, high-power arc plasma source with a pulse power system based on a Marx generator utilizing high-energy capacitors and a solid-state switching system is developed and successfully commissioned. In this paper, design features of the plasma source and the power supply system for the VEST NBI system is described and the arc plasma discharge characteristics are presented.

Effects of the non-extensive parameter on the propagation of ion acoustic waves in five-component cometary plasma system

Some important evolution nonlinear partial differential equations are derived using the reductive perturbation method for unmagnetized collisionless system of five component plasma. This plasma system is a multi-ion contains negatively and positively charged Oxygen ions (heavy ions), positive Hydrogen ions (lighter ions), hot electrons from solar origin and colder electrons from cometary origin. The positive Hydrogen ion and the two types of electrons obey \(q\)-non-extensive distributions. The derived equations have three types of ion acoustic waves, which are soliton waves, shock waves and kink waves. The effects of the non-extensive parameters for the hot electrons, the colder electrons and the Hydrogen ions on the propagation of the envelope waves are studied. The compressive and rarefactive shapes of the three envelope waves appear in this system for the first order of the power of the nonlinearity strength with different values of non-extensive parameters. For the second order, the strength of nonlinearity will increase and the compressive type of the envelope wave only appears.

Reconstruction of energy and angle distribution function of surface-emitted negative ions in hydrogen plasmas using mass spectrometry

A new method involving mass spectrometry and modeling is described in this work, which may highlight the production mechanisms of negative ions (NIs) on surface in low pressure plasmas. Positive hydrogen ions from plasma impact a sample which is biased negatively with respect to the plasma potential. NIs are produced on the surface through the ionization of sputtered and backscattered particles and detected according to their energy and mass by a mass spectrometer (MS) placed in front of the sample. The shape of the measured negative-ion energy distribution function (NIEDF) strongly differs from the NIEDF of the ions emitted by the sample because of the limited acceptance angle of the MS. The reconstruction method proposed here allows to compute the distribution function in energy and angle (NIEADF) of the NIs emitted by the sample based on the NIEDF measurements at different tilt angles of the sample. The reconstruction algorithm does not depend on the NI surface production mechanism, so it can be applied to any type of surface and/or NI. The NIEADFs for highly oriented pyrolitic graphite (HOPG) and gadolinium (low work-function metal) are presented and compared with the SRIM modeling. HOPG and Gd show comparable integrated NI yields, however the key differences in mechanisms of NI production can be identified. While for Gd the major process is backscattering of ions with the peak of NIEDF at 36 eV, in case of HOPG the sputtering contribution due to adsorbed H on the surface is also important and the NIEDF peak is found at 5 eV.

First Principles Calculations Study of Lithium-Montmorillonite for Humidity Sensor Application

In this study, we performed calculations on the water molecule adsorbed on lithium montmorillonite using first principles-calculation by means of electronic-structure calculation, with emphasis on approaches based on Density Functional Theory (DFT). The mechanism of water molecule adsorption on the surface of lithium-montmorillonite was investigated from the electronic structure point of view to seek the possibility of using montmorillonite as humidity sensor. The effects of the Van der Waals force to the electronic properties of water molecule on the surface of montmorillonite was also considered and obtained that the structure is more stable energetically. The interaction of water molecule with surface of montmorillonite yields the rotation of the hydrogen atoms of water molecule due to the occurrence of repulsive interaction between two positive ions of hydrogen of water molecule and lithium. From the calculations, lithium-montmorillonite can be considered as a good material for humidity sensor application since there is an electrical change observed even though it is a relatively small that is 0.657 eV.