Compact electrostatic beam optics for multi-element focused ion beams: simulation and experiments.

PubMed

Mathew, Jose V; Bhattacharjee, Sudeep

2011-01-01

Electrostatic beam optics for a multi-element focused ion beam (MEFIB) system comprising of a microwave multicusp plasma (ion) source is designed with the help of two widely known and commercially available beam simulation codes: AXCEL-INP and SIMION. The input parameters to the simulations are obtained from experiments carried out in the system. A single and a double Einzel lens system (ELS) with and without beam limiting apertures (S) have been investigated. For a 1 mm beam at the plasma electrode aperture, the rms emittance of the focused ion beam is found to reduce from ∼0.9 mm mrad for single ELS to ∼0.5 mm mrad for a double ELS, when S of 0.5 mm aperture size is employed. The emittance can be further improved to ∼0.1 mm mrad by maintaining S at ground potential, leading to reduction in beam spot size (∼10 μm). The double ELS design is optimized for different electrode geometrical parameters with tolerances of ±1 mm in electrode thickness, electrode aperture, inter electrode distance, and ±1° in electrode angle, providing a robust design. Experimental results obtained with the double ELS for the focused beam current and spot size, agree reasonably well with the simulations.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching

NASA Astrophysics Data System (ADS)

Salhi, Billel; Troadec, David; Boukherroub, Rabah

2017-05-01

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time. Chemical etching in aqueous solutions of TMAH at 80 °C leads to the selective dissolution of the Si planes not exposed to the ions. The preliminary results obtained in the laboratory made it possible to optimize the experimental conditions for the synthesis of 2D and 3D nanoobjects of controlled shape and size. Analysis by transmission electron microscopy and energy dispersive x-ray showed the amorphous nature of the nanostructures obtained and the presence of 5%-20% Ga in these nanoobjects. The first experiments of recrystallization by rapid thermal annealing allowed to reconstitute the crystal structure of these nanoobjects.

3D silicon shapes through bulk nano structuration by focused ion beam implantation and wet etching.

PubMed

Salhi, Billel; Troadec, David; Boukherroub, Rabah

2017-05-19

The work presented in this paper concerns the synthesis of silicon (Si) 2D and 3D nanostructures using the delayed effect, caused by implanted Ga ions, on the dissolution of Si in aqueous solutions of tetramethylammonium hydroxide (TMAH). The crystalline silicon substrates (100) are first cleaned and then hydrogenated by immersion in an aqueous solution of hydrofluoric acid. The ion implantation is then carried out by a focused ion beam by varying the dose and the exposure time. Chemical etching in aqueous solutions of TMAH at 80 °C leads to the selective dissolution of the Si planes not exposed to the ions. The preliminary results obtained in the laboratory made it possible to optimize the experimental conditions for the synthesis of 2D and 3D nanoobjects of controlled shape and size. Analysis by transmission electron microscopy and energy dispersive x-ray showed the amorphous nature of the nanostructures obtained and the presence of 5%-20% Ga in these nanoobjects. The first experiments of recrystallization by rapid thermal annealing allowed to reconstitute the crystal structure of these nanoobjects.

Use of the focusing multi-slit ion optical system at RUssian Diagnostic Injector (RUDI)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Listopad, A.; Davydenko, V.; Ivanov, A.

2012-02-15

The upgrade of the diagnostic neutral beam injector RUDI in 2010 was performed to increase the beam density at the focal plane in accordance with the requirements of charge-exchange recombination spectroscopy diagnostics. A new focusing ion-optical system (IOS) with slit beamlets and an enlarged aperture was optimized for 50% higher nominal beam current and reduced angular divergence with respect to the previous multi-aperture IOS version. The upgraded injector provides the beam current up to 3 A, the measured beam divergence in the direction along the slits is 0.35 deg. Additionally, the plasma generator was modified to extend the beam pulsemore » to 8 s.« less

Environmental sensing with optical fiber sensors processed with focused ion beam and atomic layer deposition

NASA Astrophysics Data System (ADS)

Flores, Raquel; Janeiro, Ricardo; Dahlem, Marcus; Viegas, Jaime

2015-03-01

We report an optical fiber chemical sensor based on a focused ion beam processed optical fiber. The demonstrated sensor is based on a cavity formed onto a standard 1550 nm single-mode fiber by either chemical etching, focused ion beam milling (FIB) or femtosecond laser ablation, on which side channels are drilled by either ion beam milling or femtosecond laser irradiation. The encapsulation of the cavity is achieved by optimized fusion splicing onto a standard single or multimode fiber. The empty cavity can be used as semi-curved Fabry-Pérot resonator for gas or liquid sensing. Increased reflectivity of the formed cavity mirrors can be achieved with atomic layer deposition (ALD) of alternating metal oxides. For chemical selective optical sensors, we demonstrate the same FIB-formed cavity concept, but filled with different materials, such as polydimethylsiloxane (PDMS), poly(methyl methacrylate) (PMMA) which show selective swelling when immersed in different solvents. Finally, a reducing agent sensor based on a FIB formed cavity partially sealed by fusion splicing and coated with a thin ZnO layer by ALD is presented and the results discussed. Sensor interrogation is achieved with spectral or multi-channel intensity measurements.

α7 nicotinic ACh receptors as a ligand-gated source of Ca(2+) ions: the search for a Ca(2+) optimum.

PubMed

Uteshev, Victor V

2012-01-01

The spatiotemporal distribution of cytosolic Ca(2+) ions is a key determinant of neuronal behavior and survival. Distinct sources of Ca(2+) ions including ligand- and voltage-gated Ca(2+) channels contribute to intracellular Ca(2+) homeostasis. Many normal physiological and therapeutic neuronal functions are Ca(2+)-dependent, however an excess of cytosolic Ca(2+) or a lack of the appropriate balance between Ca(2+) entry and clearance may destroy cellular integrity and cause cellular death. Therefore, the existence of optimal spatiotemporal patterns of cytosolic Ca(2+) elevations and thus, optimal activation of ligand- and voltage-gated Ca(2+) ion channels are postulated to benefit neuronal function and survival. Alpha7 nicotinic -acetylcholine receptors (nAChRs) are highly permeable to Ca(2+) ions and play an important role in modulation of neurotransmitter release, gene expression and neuroprotection in a variety of neuronal and non-neuronal cells. In this review, the focus is placed on α7 nAChR-mediated currents and Ca(2+) influx and how this source of Ca(2+) entry compares to NMDA receptors in supporting cytosolic Ca(2+) homeostasis, neuronal function and survival.

Targeted Optimization of Quasi-Symmetric Stellarators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hegna, Chris C.; Anderson, D. T.; Talmadge, J. N.

2016-10-06

The proposed research focuses on targeted areas of plasma physics dedicated to improving the stellarator concept. Research was pursued in the technical areas of edge/divertor physics in 3D configurations, magnetic island physics in stellarators, the role of 3D shaping on microinstabilities and turbulent transport and energetic ion confinement in stellarators.

Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets

PubMed Central

Zou, D. B.; Pukhov, A.; Yi, L. Q.; Zhou, H. B.; Yu, T. P.; Yin, Y.; Shao, F. Q.

2017-01-01

Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations. PMID:28218247

Laser-Driven Ion Acceleration from Plasma Micro-Channel Targets

NASA Astrophysics Data System (ADS)

Zou, D. B.; Pukhov, A.; Yi, L. Q.; Zhou, H. B.; Yu, T. P.; Yin, Y.; Shao, F. Q.

2017-02-01

Efficient energy boost of the laser-accelerated ions is critical for their applications in biomedical and hadron research. Achiev-able energies continue to rise, with currently highest energies, allowing access to medical therapy energy windows. Here, a new regime of simultaneous acceleration of ~100 MeV protons and multi-100 MeV carbon-ions from plasma micro-channel targets is proposed by using a ~1020 W/cm2 modest intensity laser pulse. It is found that two trains of overdense electron bunches are dragged out from the micro-channel and effectively accelerated by the longitudinal electric-field excited in the plasma channel. With the optimized channel size, these “superponderomotive” energetic electrons can be focused on the front surface of the attached plastic substrate. The much intense sheath electric-field is formed on the rear side, leading to up to ~10-fold ionic energy increase compared to the simple planar geometry. The analytical prediction of the optimal channel size and ion maximum energies is derived, which shows good agreement with the particle-in-cell simulations.

Efficient quasi-monoenergetic ion beams up to 18 MeV/nucleon via self-generated plasma fields in relativistic laser plasmas

NASA Astrophysics Data System (ADS)

Palaniyappan, Sasi; Huang, Chengkun; Gautier, Donald; Hamilton, Christopher; Santiago, Miguel; Kreuzer, Christian; Shah, Rahul; Fernandez, Juan; Los Alamos National Laboratory Team; Ludwig-Maximilian-University Team

2015-11-01

Table-top laser-plasma ion accelerators seldom achieve narrow energy spreads, and never without serious compromises in efficiency, particle yield, etc. Using massive computer simulations, we identify a self-organizing scheme that exploits persisting self-generated plasma electric (~ TV/m) and magnetic (~ 104 Tesla) fields to reduce the ion energy spread after the laser exits the plasma - separating the ion acceleration from the energy spread reduction. Consistent with the scheme, we experimentally demonstrate aluminum and carbon ion beams with narrow spectral peaks at energies up to 310 MeV (11.5 MeV/nucleon) and 220 MeV (18.3 MeV/nucleon), respectively, with high conversion efficiency (~ 5%, i.e., 4J out of 80J laser). This is achieved with 0.12 PW high-contrast Gaussian laser pulses irradiating planar foils with optimal thicknesses of up to 250 nm that scale with laser intensity. When increasing the focused laser intensity fourfold (by reducing the focusing optic f/number twofold), the spectral-peak energy increases twofold. These results pave the way for next generation compact accelerators suitable for applications. For example, 400 MeV (33.3 MeV/nucleon) carbon-ion beam with narrow energy spread required for ion fast ignition could be generated using PW-class lasers.

Development of Functional Surfaces on High-Density Polyethylene (HDPE) via Gas-Assisted Etching (GAE) Using Focused Ion Beams.

PubMed

Sezen, Meltem; Bakan, Feray

2015-12-01

Irradiation damage, caused by the use of beams in electron and ion microscopes, leads to undesired physical/chemical material property changes or uncontrollable modification of structures. Particularly, soft matter such as polymers or biological materials is highly susceptible and very much prone to react on electron/ion beam irradiation. Nevertheless, it is possible to turn degradation-dependent physical/chemical changes from negative to positive use when materials are intentionally exposed to beams. Especially, controllable surface modification allows tuning of surface properties for targeted purposes and thus provides the use of ultimate materials and their systems at the micro/nanoscale for creating functional surfaces. In this work, XeF2 and I2 gases were used in the focused ion beam scanning electron microscope instrument in combination with gallium ion etching of high-density polyethylene surfaces with different beam currents and accordingly different gas exposure times resulting at the same ion dose to optimize and develop new polymer surface properties and to create functional polymer surfaces. Alterations in the surface morphologies and surface chemistry due to gas-assisted etching-based nanostructuring with various processing parameters were tracked using high-resolution SEM imaging, complementary energy-dispersive spectroscopic analyses, and atomic force microscopic investigations.

Transport of a high brightness proton beam through the Munich tandem accelerator

NASA Astrophysics Data System (ADS)

Moser, M.; Greubel, C.; Carli, W.; Peeper, K.; Reichart, P.; Urban, B.; Vallentin, T.; Dollinger, G.

2015-04-01

Basic requirement for ion microprobes with sub-μm beam focus is a high brightness beam to fill the small phase space usually accepted by the ion microprobe with enough ion current for the desired application. We performed beam transport simulations to optimize beam brightness transported through the Munich tandem accelerator. This was done under the constraint of a maximum ion current of 10 μA that is allowed to be injected due to radiation safety regulations and beam power constrains. The main influence of the stripper foil in conjunction with intrinsic astigmatism in the beam transport on beam brightness is discussed. The calculations show possibilities for brightness enhancement by using astigmatism corrections and asymmetric filling of the phase space volume in the x- and y-direction.

Optimizing Dense Plasma Focus Neutron Yields with Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Kueny, Christopher; Stein, Elizabeth; Link, Anthony; Schmidt, Andrea

2016-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high density jet models fast gas puffs which allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of the jet compared to the background fill increases we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration is explored. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

Varying Radii of On-Axis Anode Hollows For kJ-Class Dense Plasma Focus

NASA Astrophysics Data System (ADS)

Shaw, Brian; Chapman, Steven; Falabella, Steven; Pankin, Alexei; Liu, Jason; Link, Anthony; Schmidt, Andréa

2017-10-01

A dense plasma focus (DPF) is a compact plasma gun that produces high energy ion beams, up to several MeV, through strong potential gradients. Motivated by particle-in-cell simulations, we have tried a series of hollow anodes on our kJ-class DPF. Each anode has varying hollow sizes, and has been studied to optimize ion beam production in Helium, reduce anode sputter, and increase neutron yields in deuterium. We diagnose the rate at which electrode material is ablated and deposited onto nearby surfaces. This is of interest in the case of solid targets, which perform poorly in the presence of sputter. We have found that the larger the hollow radius produces more energetic ion beams, higher neutron yield, and sputter less than a flat top anode. A complete comparison is presented. This work was prepared by LLNL under Contract DE-AC52-07NA27344 and supported by Office of Defense Nuclear Nonproliferation Research and Development within U.S. Department of Energy's National Nuclear Security Administration.

Irradiation of materials with short, intense ion pulses at NDCX-II

NASA Astrophysics Data System (ADS)

Seidl, P. A.; Barnard, J. J.; Feinberg, E.; Friedman, A.; Gilson, E. P.; Grote, D. P.; Ji, Q.; Kaganovich, I. D.; Ludewigt, B.; Persaud, A.; Sierra, C.; Silverman, M.; Stepanov, A. D.; Sulyman, A.; Treffert, F.; Waldron, W. L.; Zimmer, M.; Schenkel, T.

2017-06-01

We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 10^11 ions, 1-mm radius, and 2-30 ns FWHM duration have been created with corresponding fluences in the range of 0.1 to 0.7 J/cm^2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV He+ ion beam is neutralized in a drift compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing accelerator performance.

Optimal Charging Profiles with Minimal Intercalation-Induced Stresses for Lithium-Ion Batteries Using Reformulated Pseudo 2-Dimensional Models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suthar, B; Northrop, PWC; Braatz, RD

This paper illustrates the application of dynamic optimization in obtaining the optimal current profile for charging a lithium-ion battery by restricting the intercalation-induced stresses to a pre-determined limit estimated using a pseudo 2-dimensional (P2D). model. This paper focuses on the problem of maximizing the charge stored in a given time while restricting capacity fade due to intercalation-induced stresses. Conventional charging profiles for lithium-ion batteries (e.g., constant current followed by constant voltage or CC-CV) are not derived by considering capacity fade mechanisms, which are not only inefficient in terms of life-time usage of the batteries but are also slower by notmore » taking into account the changing dynamics of the system. (C) The Author(s) 2014. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives 4.0 License (CC BY-NC-ND, http://creativecommons.org/licenses/by-nc-nd/4.0/), which permits non-commercial reuse, distribution, and reproduction in any medium, provided the original work is not changed in any way and is properly cited. For permission for commercial reuse, please email: oa@electrochem.org. All rights reserved.« less

Assessment of Various Low Temperature Electrolytes in Prototype Li-Ion Cells Developed for ESMD Applications

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.

2008-01-01

Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with six different ethylene carbonate-based electrolytes optimized for low temperature. In addition to investigating the behavior in experimental cells initially, the performance of these promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells, manufactured by Yardney Technical Products and Saft America, Inc. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

Novel pharmacological targets for the rhythm control management of atrial fibrillation.

PubMed

Burashnikov, Alexander; Antzelevitch, Charles

2011-12-01

Atrial fibrillation (AF) is a growing clinical problem associated with increased morbidity and mortality. Development of safe and effective pharmacological treatments for AF is one of the greatest unmet medical needs facing our society. In spite of significant progress in non-pharmacological AF treatments (largely due to the use of catheter ablation techniques), anti-arrhythmic agents (AADs) remain first line therapy for rhythm control management of AF for most AF patients. When considering efficacy, safety and tolerability, currently available AADs for rhythm control of AF are less than optimal. Ion channel inhibition remains the principal strategy for termination of AF and prevention of its recurrence. Practical clinical experience indicates that multi-ion channel blockers are generally more optimal for rhythm control of AF compared to ion channel-selective blockers. Recent studies suggest that atrial-selective sodium channel block can lead to safe and effective suppression of AF and that concurrent inhibition of potassium ion channels may potentiate this effect. An important limitation of the ion channel block approach for AF treatment is that non-electrical factors (largely structural remodeling) may importantly determine the generation of AF, so that "upstream therapy", aimed at preventing or reversing structural remodeling, may be required for effective rhythm control management. This review focuses on novel pharmacological targets for the rhythm control management of AF. Copyright © 2011 Elsevier Inc. All rights reserved.

Scalable entanglement in trapped ions using optimal control of multimode couplings

NASA Astrophysics Data System (ADS)

Debnath, Shantanu; Choi, Taeyoung; Manning, T. Andrew; Figgatt, Caroline; Monroe, Chris

2014-05-01

We perform high fidelity multipartite entanglement of ion subsets in a chain of five Yb+ qubits using optimal pulse shaping. A focused mode-locked laser beam individually addresses qubits to couple them to multiple collective transverse modes of motion to perform entangling phase gates on pairs of adjacent qubits. Pulse shaping by modulating the amplitude and phase of the laser can drive high fidelity gates for certain pulse solutions that are relatively insensitive to detuning errors. We create entangled states in the GHZ class and witness genuine tripartite entanglement using individual state detection. This method of engineering the evolution of multiple modes scales well for large qubit registers by keeping gate times short. This work is supported by grants from the U.S. Army Research Office with funding from the DARPA OLE program, IARPA, and the MURI program; and the NSF Physics Frontier Center at JQI.

Time‐of‐flight secondary ion mass spectrometry imaging of biological samples with delayed extraction for high mass and high spatial resolutions

PubMed Central

Vanbellingen, Quentin P.; Elie, Nicolas; Eller, Michael J.; Della‐Negra, Serge; Touboul, David

2015-01-01

Rationale In Time‐of‐Flight Secondary Ion Mass Spectrometry (TOF‐SIMS), pulsed and focused primary ion beams enable mass spectrometry imaging, a method which is particularly useful to map various small molecules such as lipids at the surface of biological samples. When using TOF‐SIMS instruments, the focusing modes of the primary ion beam delivered by liquid metal ion guns can provide either a mass resolution of several thousand or a sub‐µm lateral resolution, but the combination of both is generally not possible. Methods With a TOF‐SIMS setup, a delayed extraction applied to secondary ions has been studied extensively on rat cerebellum sections in order to compensate for the effect of long primary ion bunches. Results The use of a delayed extraction has been proven to be an efficient solution leading to unique features, i.e. a mass resolution up to 10000 at m/z 385.4 combined with a lateral resolution of about 400 nm. Simulations of ion trajectories confirm the experimental determination of optimal delayed extraction and allow understanding of the behavior of ions as a function of their mass‐to‐charge ratio. Conclusions Although the use of a delayed extraction has been well known for many years and is very popular in MALDI, it is much less used in TOF‐SIMS. Its full characterization now enables secondary ion images to be recorded in a single run with a submicron spatial resolution and with a mass resolution of several thousand. This improvement is very useful when analyzing lipids on tissue sections, or rare, precious, or very small size samples. © 2015 The Authors. Rapid Communications in Mass Spectrometry published by John Wiley & Sons Ltd. PMID:26395603

Assessment and improvements of Geant4 hadronic models in the context of prompt-gamma hadrontherapy monitoring

NASA Astrophysics Data System (ADS)

Dedes, G.; Pinto, M.; Dauvergne, D.; Freud, N.; Krimmer, J.; Létang, J. M.; Ray, C.; Testa, E.

2014-04-01

Monte Carlo simulations are nowadays essential tools for a wide range of research topics in the field of radiotherapy. They also play an important role in the effort to develop a real-time monitoring system for quality assurance in proton and carbon ion therapy, by means of prompt-gamma detection. The internal theoretical nuclear models of Monte Carlo simulation toolkits are of decisive importance for the accurate description of neutral or charged particle emission, produced by nuclear interactions between beam particles and target nuclei. We assess the performance of Geant4 nuclear models in the context of prompt-gamma emission, comparing them with experimental data from proton and carbon ion beams. As has been shown in the past and further indicated in our study, the prompt-gamma yields are consistently overestimated by Geant4 by a factor of about 100% to 200% over an energy range from 80 to 310 MeV/u for the case of 12C, and to a lesser extent for 160 MeV protons. Furthermore, we focus on the quantum molecular dynamics (QMD) modeling of ion-ion collisions, in order to optimize its description of light nuclei, which are abundant in the human body and mainly anticipated in hadrontherapy applications. The optimization has been performed by benchmarking QMD free parameters with well established nuclear properties. In addition, we study the effect of this optimization on charged particle emission. With the usage of the proposed parameter values, discrepancies reduce to less than 70%, with the highest values being attributed to the nucleon-ion induced prompt-gammas. This conclusion, also confirmed by the disagreement we observe in the case of proton beams, indicates the need for further investigation on nuclear models which describe proton and neutron induced nuclear reactions.

High Resolution Separations and Improved Ion Production and Transmission in Metabolomics

PubMed Central

Metz, Thomas O.; Page, Jason S.; Baker, Erin S.; Tang, Keqi; Ding, Jie; Shen, Yufeng; Smith, Richard D.

2008-01-01

The goal of metabolomics analyses is the detection and quantitation of as many sample components as reasonably possible in order to identify compounds or “features” that can be used to characterize the samples under study. When utilizing electrospray ionization to produce ions for analysis by mass spectrometry (MS), it is important that metabolome sample constituents be efficiently separated prior to ion production, in order to minimize ionization suppression and thereby extend the dynamic range of the measurement, as well as the coverage of the metabolome. Similarly, optimization of the MS inlet and interface can lead to increased measurement sensitivity. This perspective review will focus on the role of high resolution liquid chromatography (LC) separations in conjunction with improved ion production and transmission for LC-MS-based metabolomics. Additional emphasis will be placed on the compromise between metabolome coverage and sample analysis throughput. PMID:19255623

Three-dimensional microstructural characterization of bulk plutonium and uranium metals using focused ion beam technique

NASA Astrophysics Data System (ADS)

Chung, Brandon W.; Erler, Robert G.; Teslich, Nick E.

2016-05-01

Nuclear forensics requires accurate quantification of discriminating microstructural characteristics of the bulk nuclear material to identify its process history and provenance. Conventional metallographic preparation techniques for bulk plutonium (Pu) and uranium (U) metals are limited to providing information in two-dimension (2D) and do not allow for obtaining depth profile of the material. In this contribution, use of dual-beam focused ion-beam/scanning electron microscopy (FIB-SEM) to investigate the internal microstructure of bulk Pu and U metals is demonstrated. Our results demonstrate that the dual-beam methodology optimally elucidate microstructural features without preparation artifacts, and the three-dimensional (3D) characterization of inner microstructures can reveal salient microstructural features that cannot be observed from conventional metallographic techniques. Examples are shown to demonstrate the benefit of FIB-SEM in improving microstructural characterization of microscopic inclusions, particularly with respect to nuclear forensics.

Three-dimensional microstructural characterization of bulk plutonium and uranium metals using focused ion beam technique

DOE PAGES

Chung, Brandon W.; Erler, Robert G.; Teslich, Nick E.

2016-03-03

Nuclear forensics requires accurate quantification of discriminating microstructural characteristics of the bulk nuclear material to identify its process history and provenance. Conventional metallographic preparation techniques for bulk plutonium (Pu) and uranium (U) metals are limited to providing information in two-dimension (2D) and do not allow for obtaining depth profile of the material. In this contribution, use of dual-beam focused ion-beam/scanning electron microscopy (FIB-SEM) to investigate the internal microstructure of bulk Pu and U metals is demonstrated. Our results demonstrate that the dual-beam methodology optimally elucidate microstructural features without preparation artifacts, and the three-dimensional (3D) characterization of inner microstructures can revealmore » salient microstructural features that cannot be observed from conventional metallographic techniques. As a result, examples are shown to demonstrate the benefit of FIB-SEM in improving microstructural characterization of microscopic inclusions, particularly with respect to nuclear forensics.« less

The role of ion optics modeling in the design and development of ion mobility spectrometers

NASA Astrophysics Data System (ADS)

Griffin, Matthew T.

2005-05-01

Detection of trace gases by ion mobility spectroscopy (IMS) has become common in recent years. In fact, IMS devices are the most commonly deployed military devices for the detection of classical chemical warfare agents (CWA). IMS devices are protecting the homeland by aiding first responders in the identification of toxic industrial chemicals (TICs) and providing explosive and narcotic screening systems. Spurred by the asymmetric threat posed by new threat agents and the ever expanding list of toxic chemicals, research in the development, improvement, and optimization of IMS systems has increased. Much of the research is focused on increasing the sensitivity and selectivity of IMS systems. Ion optics is a large area of study in the field of mass spectrometry, but has been mostly overlooked in the design and development of IMS systems. Ion optics provides insight into particle trajectories, duty cycle, and efficiency of these systems. This paper will outline the role that ion optics can have in the development of IMS systems and introduce the trade space for traditional IMS as well as differential mobility spectroscopy.

Irradiation of materials with short, intense ion pulses at NDCX-II

DOE PAGES

Seidl, P. A.; Barnard, J. J.; Feinberg, E.; ...

2017-05-31

Abstract We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam-driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 10 11ions, 1 mm radius, and 2–30 ns full width at half maximum duration have been created with corresponding fluences in the range of 0.1–0.7 J/cm 2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV [megaelectronvolt (10 6eV)] He +ion beam is neutralized in a driftmore » compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. Quantitative comparison of detailed particle-in-cell simulations with the experiment plays an important role in optimizing accelerator performance.« less

Irradiation of materials with short, intense ion pulses at NDCX-II

DOE PAGES

Seidl, P. A.; Barnard, J. J.; Feinberg, E.; ...

2017-05-31

Here, we present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam-driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 10 11 ions, 1 mm radius, and 2–30 ns full width at half maximum duration have been created with corresponding fluences in the range of 0.1–0.7 J/cm 2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV [megaelectronvolt (10 6 eV)] He + ion beam is neutralizedmore » in a drift compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. In conclusion, quantitative comparison of detailed particle-in-cell simulations with the experiment plays an important role in optimizing accelerator performance« less

Irradiation of materials with short, intense ion pulses at NDCX-II

DOE Office of Scientific and Technical Information (OSTI.GOV)

Seidl, P. A.; Barnard, J. J.; Feinberg, E.

Abstract We present an overview of the performance of the Neutralized Drift Compression Experiment-II (NDCX-II) accelerator at Berkeley Lab, and report on recent target experiments on beam-driven melting and transmission ion energy loss measurements with nanosecond and millimeter-scale ion beam pulses and thin tin foils. Bunches with around 10 11ions, 1 mm radius, and 2–30 ns full width at half maximum duration have been created with corresponding fluences in the range of 0.1–0.7 J/cm 2. To achieve these short pulse durations and mm-scale focal spot radii, the 1.1 MeV [megaelectronvolt (10 6eV)] He +ion beam is neutralized in a driftmore » compression section, which removes the space charge defocusing effect during final compression and focusing. The beam space charge and drift compression techniques resemble necessary beam conditions and manipulations in heavy ion inertial fusion accelerators. Quantitative comparison of detailed particle-in-cell simulations with the experiment plays an important role in optimizing accelerator performance.« less

System OptimizatIon of the Glow Discharge Optical Spectroscopy Technique Used for Impurity Profiling of ION Implanted Gallium Arsenide.

DTIC Science & Technology

1980-12-01

AFIT/GEO/EE/80D-1 I -’ SYSTEM OPTIMIZATION OF THE GLOW DISCHARGE OPTICAL SPECTROSCOPY TECHNIQUE USED FOR IMPURITY PROFILING OF ION IMPLANTED GALLIUM ...EE/80D-1 (\\) SYSTEM OPTIMIZATION OF THE GLOW DISCHARGE OPTICAL SPECTROSCOPY TECHNIQUE USED FOR IMPURITY PROFILING OF ION IMPLANTED GALLIUM ARSENIDE...semiconductors, specifically annealed and unan- nealed ion implanted gallium arsenide (GaAs). Methods to improve the sensitivity of the GDOS system have

Si amorphization by focused ion beam milling: Point defect model with dynamic BCA simulation and experimental validation.

PubMed

Huang, J; Loeffler, M; Muehle, U; Moeller, W; Mulders, J J L; Kwakman, L F Tz; Van Dorp, W F; Zschech, E

2018-01-01

A Ga focused ion beam (FIB) is often used in transmission electron microscopy (TEM) analysis sample preparation. In case of a crystalline Si sample, an amorphous near-surface layer is formed by the FIB process. In order to optimize the FIB recipe by minimizing the amorphization, it is important to predict the amorphous layer thickness from simulation. Molecular Dynamics (MD) simulation has been used to describe the amorphization, however, it is limited by computational power for a realistic FIB process simulation. On the other hand, Binary Collision Approximation (BCA) simulation is able and has been used to simulate ion-solid interaction process at a realistic scale. In this study, a Point Defect Density approach is introduced to a dynamic BCA simulation, considering dynamic ion-solid interactions. We used this method to predict the c-Si amorphization caused by FIB milling on Si. To validate the method, dedicated TEM studies are performed. It shows that the amorphous layer thickness predicted by the numerical simulation is consistent with the experimental data. In summary, the thickness of the near-surface Si amorphization layer caused by FIB milling can be well predicted using the Point Defect Density approach within the dynamic BCA model. Copyright © 2017 Elsevier B.V. All rights reserved.

Plasma Diagnostics: Use and Justification in an Industrial Environment

NASA Astrophysics Data System (ADS)

Loewenhardt, Peter

1998-10-01

The usefulness and importance of plasma diagnostics have played a major role in the development of plasma processing tools in the semiconductor industry. As can be seen through marketing materials from semiconductor equipment manufacturers, results from plasma diagnostic equipment can be a powerful tool in selling the technological leadership of tool design. Some diagnostics have long been used for simple process control such as optical emission for endpoint determination, but in recent years more sophisticated and involved diagnostic tools have been utilized in chamber and plasma source development and optimization. It is now common to find an assortment of tools at semiconductor equipment companies such as Langmuir probes, mass spectrometers, spatial optical emission probes, impedance, ion energy and ion flux probes. An outline of how the importance of plasma diagnostics has grown at an equipment manufacturer over the last decade will be given, with examples of significant and useful results obtained. Examples will include the development and optimization of an inductive plasma source, trends and hardware effects on ion energy distributions, mass spectrometry influences on process development and investigations of plasma-wall interactions. Plasma diagnostic focus, in-house development and proliferation in an environment where financial justification requirements are both strong and necessary will be discussed.

Synthesis and acid digestion of biomorphic ceramics: determination of alkaline and alkaline earth ions.

PubMed

Bosch Ojeda, Catalina; Sánchez Rojas, Fuensanta; Cano Pavón, José Manuel

2007-09-01

Ceramic and glass are some of the more recent engineering materials and those that are most resistant to environmental conditions. They belong to advanced materials in that they are being developed for the aerospace and electronics industries. In the last decade, a new class of ceramic materials has been the focus of particular attention. The materials were produced with natural, renewable resources (wood or wood-based products). In this work, we have synthesised a new biomorphic ceramic material from oak wood and Si infiltration. After the material characterization, we have optimized the dissolution of the sample by acid attack in an oven under microwave irradiation. Experimental designs were used as a multivariate strategy for the evaluation of the effects of varying several variables at the same time. The optimization was performed in two steps using factorial design for preliminary evaluation and a Draper-Lin design for determination of the critical experimental conditions. Five variables (time, power, volume of HNO3, volume H2SO4 and volume of HF) were considered as factors and as a response the concentration of different metal ions in the optimization process. Interactions between analytical factors and their optimal levels were investigated using a Draper-Lin design.

Neutral Beam Injection System for the SHIP Experiment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdrashitov, G.F.; Abdrashitov, A.G.; Anikeev, A.V.

2005-01-15

The injector ion source is based on an arcdischarge plasma box. The plasma emitter is produced by a 1 kA arc discharge in deuterium. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase its efficiency and improve homogeneity of the plasma emitter. The ion beam is extracted by a 4-electrodes ion optical system (IOS). Initial beam diameter is 200 mm. The grids of the IOS have a spherical curvature for geometrical focusing of the beam. The optimal IOS geometry and grid potentials were found by means of numerical simulation tomore » provide precise beam formation. The measured angular divergence of the beam is 0.025 rad, which corresponds to a 4.7 cm Gaussian radius of the beam profile measured at focal point.« less

Immobilization of metallothionein to carbon paste electrode surface via anti-MT antibodies and its use for biosensing of silver.

PubMed

Trnkova, Libuse; Krizkova, Sona; Adam, Vojtech; Hubalek, Jaromir; Kizek, Rene

2011-01-15

In this paper, heavy metal biosensor based on immobilization of metallothionein (MT) to the surface of carbon paste electrode (CPE) via anti-MT-antibodies is reported. First, the evaluation of MT electroactivity was done. The attention was focused on the capturing of MT to the CPE surface. Antibodies incorporated and mixed into carbon paste were stable; even after two weeks the observed changes in signal height were lower than 5%. Further, the interaction of MT with polyclonal chicken antibodies incorporated in carbon paste electrode was determined by square-wave voltammetry. In the voltammogram, two signals--labelled as cys(MT) and W(a)--were observed. The cys(MT) corresponded to -SH moieties of MT and W(a) corresponded to tryptophan residues of chicken antibodies. Time of interaction (300 s) and MT concentration (125 μg/ml) were optimized to suggest a silver(I) ions biosensor. Biosensor (CPE modified with anti-MT antibody) prepared under the optimized conditions was then used for silver(I) ions detection. The detection limit (3 S/N) for silver(I) ions was estimated as 0.5 nM. The proposed biosensor was tested by detection spiking of silver(I) ions in various water samples (from very pure distilled water to rainwater). Recoveries varied from 74 to 104%. Copyright © 2010 Elsevier B.V. All rights reserved.

Development of double-pulse lasers ablation system for generating gold ion source under applying an electric field

NASA Astrophysics Data System (ADS)

Khalil, A. A. I.

2015-12-01

Double-pulse lasers ablation (DPLA) technique was developed to generate gold (Au) ion source and produce high current under applying an electric potential in an argon ambient gas environment. Two Q-switched Nd:YAG lasers operating at 1064 and 266 nm wavelengths are combined in an unconventional orthogonal (crossed-beam) double-pulse configuration with 45° angle to focus on a gold target along with a spectrometer for spectral analysis of gold plasma. The properties of gold plasma produced under double-pulse lasers excitation were studied. The velocity distribution function (VDF) of the emitted plasma was studied using a dedicated Faraday-cup ion probe (FCIP) under argon gas discharge. The experimental parameters were optimized to attain the best signal to noise (S/N) ratio. The results depicted that the VDF and current signals depend on the discharge applied voltage, laser intensity, laser wavelength and ambient argon gas pressure. A seven-fold increases in the current signal by increasing the discharge applied voltage and ion velocity under applying double-pulse lasers field. The plasma parameters (electron temperature and density) were also studied and their dependence on the delay (times between the excitation laser pulse and the opening of camera shutter) was investigated as well. This study could provide significant reference data for the optimization and design of DPLA systems engaged in laser induced plasma deposition thin films and facing components diagnostics.

Experimental test of an online ion-optics optimizer

NASA Astrophysics Data System (ADS)

Amthor, A. M.; Schillaci, Z. M.; Morrissey, D. J.; Portillo, M.; Schwarz, S.; Steiner, M.; Sumithrarachchi, Ch.

2018-07-01

A technique has been developed and tested to automatically adjust multiple electrostatic or magnetic multipoles on an ion optical beam line - according to a defined optimization algorithm - until an optimal tune is found. This approach simplifies the process of determining high-performance optical tunes, satisfying a given set of optical properties, for an ion optical system. The optimization approach is based on the particle swarm method and is entirely model independent, thus the success of the optimization does not depend on the accuracy of an extant ion optical model of the system to be optimized. Initial test runs of a first order optimization of a low-energy (<60 keV) all-electrostatic beamline at the NSCL show reliable convergence of nine quadrupole degrees of freedom to well-performing tunes within a reasonable number of trial solutions, roughly 500, with full beam optimization run times of roughly two hours. Improved tunes were found both for quasi-local optimizations and for quasi-global optimizations, indicating a good ability of the optimizer to find a solution with or without a well defined set of initial multipole settings.

Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

NASA Astrophysics Data System (ADS)

Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

2017-08-01

At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on Exotic Beams at ISOLDE: A Laboratory Portrait special issue.

The state of autotrophic ethanol production in Cyanobacteria.

PubMed

Dexter, J; Armshaw, P; Sheahan, C; Pembroke, J T

2015-07-01

Ethanol production directly from CO2 , utilizing genetically engineered photosynthetic cyanobacteria as a biocatalyst, offers significant potential as a renewable and sustainable source of biofuel. Despite the current absence of a commercially successful production system, significant resources have been deployed to realize this goal. Utilizing the pyruvate decarboxylase from Zymomonas species, metabolically derived pyruvate can be converted to ethanol. This review of both peer-reviewed and patent literature focuses on the genetic modifications utilized for metabolic engineering and the resultant effect on ethanol yield. Gene dosage, induced expression and cassette optimizat-ion have been analyzed to optimize production, with production rates of 0·1-0·5 g L(-1) day(-1) being achieved. The current 'toolbox' of molecular manipulations and future directions focusing on applicability, addressing the primary challenges facing commercialization of cyanobacterial technologies are discussed. © 2015 The Society for Applied Microbiology.

Ion transfer from an atmospheric pressure ion funnel into a mass spectrometer with different interface options: Simulation-based optimization of ion transmission efficiency.

PubMed

Mayer, Thomas; Borsdorf, Helko

2016-02-15

We optimized an atmospheric pressure ion funnel (APIF) including different interface options (pinhole, capillary, and nozzle) regarding a maximal ion transmission. Previous computer simulations consider the ion funnel itself and do not include the geometry of the following components which can considerably influence the ion transmission into the vacuum stage. Initially, a three-dimensional computer-aided design (CAD) model of our setup was created using Autodesk Inventor. This model was imported to the Autodesk Simulation CFD program where the computational fluid dynamics (CFD) were calculated. The flow field was transferred to SIMION 8.1. Investigations of ion trajectories were carried out using the SDS (statistical diffusion simulation) tool of SIMION, which allowed us to evaluate the flow regime, pressure, and temperature values that we obtained. The simulation-based optimization of different interfaces between an atmospheric pressure ion funnel and the first vacuum stage of a mass spectrometer require the consideration of fluid dynamics. The use of a Venturi nozzle ensures the highest level of transmission efficiency in comparison to capillaries or pinholes. However, the application of radiofrequency (RF) voltage and an appropriate direct current (DC) field leads to process optimization and maximum ion transfer. The nozzle does not hinder the transfer of small ions. Our high-resolution SIMION model (0.01 mm grid unit(-1) ) under consideration of fluid dynamics is generally suitable for predicting the ion transmission through an atmospheric-vacuum system for mass spectrometry and enables the optimization of operational parameters. A Venturi nozzle inserted between the ion funnel and the mass spectrometer permits maximal ion transmission. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Development of an ion mobility spectrometer with UV ionization source to detect ketones and BTX

NASA Astrophysics Data System (ADS)

Ni, Kai; Guo, Jingran; Ou, Guangli; Lei, Yu; Wang, Xiaohao

2014-11-01

Ion mobility spectrometry (IMS) is an attractive material analysis technology for developing a miniaturized volatile organic compounds (VOCs) on-site monitoring sensor. Having simple instrumentation, IMS is especially suitable when portability and sensitivity are required. In this work, we designed an ion mobility spectrometer with UV ionization. The geometric parameters of the UV-IMS were optimized based on a numerical simulation. The simulation results demonstrated that the drift electric field in the drift region was approximately homogenous and in the reaction region had an ion focusing effect, which could improve the sensitivity and resolving power of the IMS. The UV-IMS has been constructed and used to detect VOCs, such as acetone, benzene, toluene and m-xylene (BTX). The resolution of these substance measured from the UV-IMS in the atmospheric conditions are about 30 and the limit of detection (LOD) is low to ppmv. The ion mobility module and electric circuit are integrated in a main PCB, which can facilitate mass production and miniaturization. The present UV-IMS is expected to become a tool of choice for the on-site monitoring for VOCs.

Performance of Low Temperature Electrolytes in Experimental and Prototype Li-Ion Cells

NASA Technical Reports Server (NTRS)

Smart, M. C.; Ratnakumar, B. V.; Whitcanack, L. D.

2007-01-01

Due to their attractive properties and proven success, Li-ion batteries have become identified as the battery chemistry of choice for a number of future NASA missions. A number of these applications would be greatly benefited by improved performance of Li-ion technology over a wider operating temperature range, especially at low temperatures, such as future ESMD missions. In many cases, these technology improvements may be mission enabling, and at the very least mission enhancing. In addition to aerospace applications, the DoE has interest in developing advanced Li-ion batteries that can operate over a wide temperature range to enable terrestrial HEV applications. Thus, our focus at JPL in recent years has been to extend the operating temperature range of Li-ion batteries, especially at low temperatures. To accomplish this, the main focus of the research has been devoted to developing improved lithium-ion conducting electrolytes. In the present paper, we would like to present some of the results we have obtained with ethylene carbonate-based electrolytes optimized for low temperature in experimental MCMB-LiNixCo1_x0 2 cells. In addition to obtaining discharge and charge rate performance data at various temperatures, electrochemical measurements were performed on individual electrodes (made possible by the incorporation of Li reference electrodes), including EIS, linear polarization and Tafel polarization measurements. The combination of techniques enables the elucidation of various trends associated with electrolyte composition. In addition to investigating the behavior in experimental cells, the performance of many promising low temperature electrolytes was demonstrated in large capacity, aerospace quality Li-ion prototype cells. These cells were subjected to a number of performance tests, including discharge rate characterization, charge rate characterization, cycle life performance at various temperatures, and power characterization tests.

A novel membrane-based process to isolate peroxidase from horseradish roots: optimization of operating parameters.

PubMed

Liu, Jianguo; Yang, Bo; Chen, Changzhen

2013-02-01

The optimization of operating parameters for the isolation of peroxidase from horseradish (Armoracia rusticana) roots with ultrafiltration (UF) technology was systemically studied. The effects of UF operating conditions on the transmission of proteins were quantified using the parameter scanning UF. These conditions included solution pH, ionic strength, stirring speed and permeate flux. Under optimized conditions, the purity of horseradish peroxidase (HRP) obtained was greater than 84 % after a two-stage UF process and the recovery of HRP from the feedstock was close to 90 %. The resulting peroxidase product was then analysed by isoelectric focusing, SDS-PAGE and circular dichroism, to confirm its isoelectric point, molecular weight and molecular secondary structure. The effects of calcium ion on HRP specific activities were also experimentally determined.

Mini-conference on helicon plasma sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scime, E. E.; Keesee, A. M.; Boswell, R. W.

2008-05-15

The first two sessions of this mini-conference focused attention on two areas of helicon source research: The conditions for optimal helicon source performance and the origins of energetic electrons and ions in helicon source plasmas. The final mini-conference session reviewed novel applications of helicon sources, such as mixed plasma source systems and toroidal helicon sources. The session format was designed to stimulate debate and discussion, with considerable time available for extended discussion.

High resolution energy analyzer for broad ion beam characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanarov, V.; Hayes, A.; Yevtukhov, R.

2008-09-15

Characterization of the ion energy distribution function (IEDF) of low energy high current density ion beams by conventional retarding field and deflection type energy analyzers is limited due to finite ion beam emittance and beam space charge spreading inside the analyzer. These deficiencies are, to a large extent, overcome with the recent development of the variable-focusing retarding field energy analyzer (RFEA), which has a cylindrical focusing electrode preceding the planar retarding grid. The principal concept of this analyzer is conversion of a divergent charged particle beam into a quasiparallel beam before analyzing it by the planar retarding field. This allowsmore » analysis of the beam particle total kinetic energy distribution with greatly improved energy resolution. Whereas this concept was first applied to analyze 5-10 keV pulsed electron beams, the present authors have adapted it to analyze the energy distribution of a low energy ({<=}1 KeV) broad ion beam. In this paper we describe the RFEA design, which was modified from the original, mainly as required by the specifics of broad ion beam energy analysis, and the device experimental characterization and modeling results. Among the modifications, an orifice electrode placed in front of the RFEA provides better spatial resolution of the broad ion beam ion optics emission region and reduces the beam plasma density in the vicinity of analyzer entry. An electron repeller grid placed in front of the RFEA collector was found critical for suppressing secondary electrons, both those incoming to the collector and those released from its surface, and improved energy spectrum measurement repeatability and accuracy. The use of finer mesh single- and double-grid retarding structures reduces the retarding grid lens effect and improves the analyzer energy resolution and accuracy of the measured spectrum mean energy. However, additional analyzer component and configuration improvements did not further change the analyzed IEDF shape or mean energy value. This led us to conclude that the optimized analyzer construction provides an energy resolution considerably narrower than the investigated ion beam energy spectrum full width at half maximum, and the derived energy spectrum is an objective and accurate representation of the analyzed broad ion beam energy distribution characteristics. A quantitative study of the focusing voltage and retarding grid field effects based on the experimental data and modeling results have supported this conclusion.« less

High Power Hydrogen Injector with Beam Focusing for Plasma Heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deichuli, P.P.; Ivanov, A.A.; Korepanov, S.A.

2005-01-15

High power neutral beam injector has been developed with the atom energy of 25 keV, a current of 60 A, and several milliseconds pulse duration. Six of these injectors will be used for upgrade of the atomic injection system at central cell of a Gas Dynamic Trap (GDT) device and 2 injectors are planned for SHIP experiment.The injector ion source is based on an arc discharge plasma box. The plasma emitter is produced by a 1 kA arc discharge in hydrogen. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increasemore » its efficiency and improve homogeneity of the plasma emitter. The ion beam is extracted by a 4-electrodes ion optical system (IOS). Initial beam diameter is 200 mm. The grids of the IOS have a spherical curvature for geometrical focusing of the beam. The optimal IOS geometry and grid potentials were found with the numerical simulation to provide precise beam formation. The measured angular divergence of the beam is 0.02 rad, which corresponds to the 2.5 cm Gaussian radius of the beam profile measured at focal point.« less

Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vondrasek, R.; Kutsaev, Sergey; Delahaye, P.

2012-11-15

The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a {sup 252}Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium. To date the charge breeding program has focused on optimizing these mid-mass beams, achieving high charge breeding efficienciesmore » of both gaseous and solid species including 14.7% for the radioactive species {sup 143}Ba{sup 27+}. In an effort to better understand the charge breeding mechanism, we have recently focused on the low-mass species sodium and potassium which up to present have been difficult to charge breed efficiently. Unprecedented charge breeding efficiencies of 10.1% for {sup 23}Na{sup 7+} and 17.9% for {sup 39}K{sup 10+} were obtained injecting stable Na{sup +} and K{sup +} beams from a surface ionization source.« less

Improved charge breeding efficiency of light ions with an electron cyclotron resonance ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vondrasek, R.; Delahaye, P.; Kutsaev, Sergey

2012-11-01

The Californium Rare Isotope Breeder Upgrade is a new radioactive beam facility for the Argonne Tandem Linac Accelerator System (ATLAS). The facility utilizes a 252Cf fission source coupled with an electron cyclotron resonance ion source to provide radioactive beam species for the ATLAS experimental program. The californium fission fragment distribution provides nuclei in the mid-mass range which are difficult to extract from production targets using the isotope separation on line technique and are not well populated by low-energy fission of uranium. To date the charge breeding program has focused on optimizing these mid-mass beams, achieving high charge breeding efficiencies ofmore » both gaseous and solid species including 14.7% for the radioactive species 143Ba27+. In an effort to better understand the charge breeding mechanism, we have recently focused on the low-mass species sodium and potassium which up to present have been difficult to charge breed efficiently. Unprecedented charge breeding efficiencies of 10.1% for 23Na7+ and 17.9% for 39K10+ were obtained injecting stable Na+ and K+ beams from a surface ionization source.« less

Erbium ion implantation into diamond - measurement and modelling of the crystal structure.

PubMed

Cajzl, Jakub; Nekvindová, Pavla; Macková, Anna; Malinský, Petr; Sedmidubský, David; Hušák, Michal; Remeš, Zdeněk; Varga, Marián; Kromka, Alexander; Böttger, Roman; Oswald, Jiří

2017-02-22

Diamond is proposed as an extraordinary material usable in interdisciplinary fields, especially in optics and photonics. In this contribution we focus on the doping of diamond with erbium as an optically active centre. In the theoretical part of the study based on DFT simulations we have developed two Er-doped diamond structural models with 0 to 4 carbon vacancies in the vicinity of the Er atom and performed geometry optimizations by the calculation of cohesive energies and defect formation energies. The theoretical results showed an excellent agreement between the calculated and experimental cohesive energies for the parent diamond. The highest values of cohesive energies and the lowest values of defect formation energies were obtained for models with erbium in the substitutional carbon position with 1 or 3 vacancies in the vicinity of the erbium atom. From the geometry optimization the structural model with 1 vacancy had an octahedral symmetry whereas the model with 3 vacancies had a coordination of 10 forming a trigonal structure with a hexagonal ring. In the experimental part, erbium doped diamond crystal samples were prepared by ion implantation of Er + ions using ion implantation fluences ranging from 1 × 10 14 ions per cm 2 to 5 × 10 15 ions per cm 2 . The experimental results revealed a high degree of diamond structural damage after the ion implantation process reaching up to 69% of disordered atoms in the samples. The prepared Er-doped diamond samples annealed at the temperatures of 400, 600 and 800 °C in a vacuum revealed clear luminescence, where the 〈110〉 cut sample has approximately 6-7 times higher luminescence intensity than the 〈001〉 cut sample with the same ion implantation fluence. The reported results are the first demonstration of the Er luminescence in the single crystal diamond structure for the near-infrared spectral region.

Analysis of FIB-induced damage by electron channelling contrast imaging in the SEM.

PubMed

Gutierrez-Urrutia, Ivan

2017-01-01

We have investigated the Ga + ion-damage effect induced by focused ion beam (FIB) milling in a [001] single crystal of a 316 L stainless steel by the electron channelling contrast imaging (ECCI) technique. The influence of FIB milling on the characteristic electron channelling contrast of surface dislocations was analysed. The ECCI approach provides sound estimation of the damage depth produced by FIB milling. For comparison purposes, we have also studied the same milled surface by a conventional electron backscatter diffraction (EBSD) approach. We observe that the ECCI approach provides further insight into the Ga + ion-damage phenomenon than the EBSD technique by direct imaging of FIB artefacts in the scanning electron microscope. We envisage that the ECCI technique may be a convenient tool to optimize the FIB milling settings in applications where the surface crystal defect content is relevant. © 2016 The Authors Journal of Microscopy © 2016 Royal Microscopical Society.

In situ ion-beam-induced luminescence analysis for evaluating a micrometer-scale radio-photoluminescence glass dosimeter

NASA Astrophysics Data System (ADS)

Kawabata, Shunsuke; Kada, Wataru; Parajuli, Raj Kumar; Matsubara, Yoshinori; Sakai, Makoto; Miura, Kenta; Satoh, Takahiro; Koka, Masashi; Yamada, Naoto; Kamiya, Tomihiro; Hanaizumi, Osamu

2016-06-01

Micrometer-scale responses of radio-photoluminescence (RPL) glass dosimeters to focused ionized particle radiation were evaluated by combining ion-beam-induced luminescence (IBIL) and proton beam writing (PBW) using a 3 MeV focused proton microbeam. RPL phosphate glass dosimeters doped with ionic Ag or Cu activators at concentrations of 0.2 and 0.1% were fabricated, and their scintillation intensities were evaluated by IBIL spectroscopy under a PBW micropatterning condition. Compared with the Ag-doped dosimeter, the Cu-doped dosimeter was more tolerant of the radiation, while the peak intensity of its luminescence was lower, under the precise dose control of the proton microprobe. Proton-irradiated areas were successfully recorded using these dosimeters and their RPL centers were visualized under 375 nm ultraviolet light. The reproduction of the irradiated region by post-RPL imaging suggests that precise estimation of irradiation dose using microdosimeters can be accomplished by optimizing RPL glass dosimeters for various proton microprobe applications in organic material analysis and in micrometer-scale material modifications.

Enabling High Fidelity Measurements of Energy and Pitch Angle for Escaping Energetic Ions with a Fast Ion Loss Detector

NASA Astrophysics Data System (ADS)

Chaban, R.; Pace, D. C.; Marcy, G. R.; Taussig, D.

2016-10-01

Energetic ion losses must be minimized in burning plasmas to maintain fusion power, and existing tokamaks provide access to energetic ion parameter regimes that are relevant to burning machines. A new Fast Ion Loss Detector (FILD) probe on the DIII-D tokamak has been optimized to resolve beam ion losses across a range of 30 - 90 keV in energy and 40° to 80° in pitch angle, thereby providing valuable measurements during many different experiments. The FILD is a magnetic spectrometer; once inserted into the tokamak, the magnetic field allows energetic ions to pass through a collimating aperture and strike a scintillator plate that is imaged by a wide view camera and narrow view photomultiplier tubes (PMTs). The design involves calculating scintillator strike patterns while varying probe geometry. Calculated scintillator patterns are then used to design an optical system that allows adjustment of the focus regions for the 1 MS/s resolved PMTs. A synthetic diagnostic will be used to determine the energy and pitch angle resolution that can be attained in DIII-D experiments. Work supported in part by US DOE under the Science Undergraduate Laboratory Internship (SULI) program and under DE-FC02-04ER54698.

Controlling the Transport of an Ion: Classical and Quantum Mechanical Solutions

DTIC Science & Technology

2014-07-09

quantum systems: tools, achievements, and limitations Christiane P Koch Shortcuts to adiabaticity for an ion in a rotating radially- tight trap M Palmero...Keywords: coherent control, ion traps, quantum information, optimal control theory 1. Introduction Control methods are key enabling techniques in many...figure 6. 3.4. Feasibility analysis of quantum optimal control Numerical optimization of the wavepacket motion is expected to become necessary once

Experimental measurement of the 4-d transverse phase space map of a heavy ion beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopkins, H S

1997-12-01

The development and employment of a new diagnostic instrument for characterizing intense, heavy ion beams is reported on. This instrument, the ''Gated Beam Imager'' or ''GBI'' was designed for use on Lawrence Livermore National Laboratory Heavy Ion Fusion Project's ''Small Recirculator'', an integrated, scaled physics experiment and engineering development project for studying the transport and control of intense heavy ion beams as inertial fusion drivers in the production of electric power. The GBI allows rapid measurement and calculation of a heavy ion beam's characteristics to include all the first and second moments of the transverse phase space distribution, transverse emittance,more » envelope parameters and beam centroid. The GBI, with appropriate gating produces a time history of the beam resulting in a 4-D phase-space and time ''map'' of the beam. A unique capability of the GBI over existing diagnostic instruments is its ability to measure the ''cross'' moments between the two transverse orthogonal directions. Non-zero ''cross'' moments in the alternating gradient lattice of the Small Recirculator are indicative of focusing element rotational misalignments contributing to beam emittance growth. This emittance growth, while having the same effect on the ability to focus a beam as emittance growth caused by non-linear effects, is in principle removable by an appropriate number of focusing elements. The instrument uses the pepperpot method of introducing a plate with many pinholes into the beam and observing the images of the resulting beamlets as they interact with a detector after an appropriate drift distance. In order to produce adequate optical signal and repeatability, the detector was chosen to be a microchannel plate (MCP) with a phosphor readout screen. The heavy ions in the pepperpot beamlets are stopped in the MCP's thin front metal anode and the resulting secondary electron signal is amplified and proximity-focused onto the phosphor while maintaining the spatial and intensity characteristics of the heavy ion beamlets. The MCP used in this manner is a sensitive, accurate, and long-lasting detector, resistant against signal degradation experienced by previous methods of intense heavy ion beam detection and imaging. The performance of the GBI was benchmarked against existing mechanical emittance diagnostics and the results of sophisticated beam transport numerical simulation codes to demonstrate its usefulness as a diagnostic tool. A method of beam correction to remove the effects of quadrupole focusing element rotational misalignments is proposed using data obtainable from a GBI. An optimizing code was written to determine the parameters of the correction system elements based on input from the GBI. The results of this code for the Small Recirculator beam are reported on.« less

An integrated time-of-flight versus residual energy subsystem for a compact dual ion composition experiment for space plasmas

NASA Astrophysics Data System (ADS)

Desai, M. I.; Ogasawara, K.; Ebert, R. W.; McComas, D. J.; Allegrini, F.; Weidner, S. E.; Alexander, N.; Livi, S. A.

2015-05-01

We have developed a novel concept for a Compact Dual Ion Composition Experiment (CoDICE) that simultaneously provides high quality plasma and energetic ion composition measurements over 6 decades in ion energy in a wide variety of space plasma environments. CoDICE measures the two critical ion populations in space plasmas: (1) mass and ionic charge state composition and 3D velocity and angular distributions of ˜10 eV/q-40 keV/q plasma ions—CoDICE-Lo and (2) mass composition, energy spectra, and angular distributions of ˜30 keV-10 MeV energetic ions—CoDICE-Hi. CoDICE uses a common, integrated Time-of-Flight (TOF) versus residual energy (E) subsystem for measuring the two distinct ion populations. This paper describes the CoDICE design concept, and presents results of the laboratory tests of the TOF portion of the TOF vs. E subsystem, focusing specifically on (1) investigation of spill-over and contamination rates on the start and stop microchannel plate (MCP) anodes vs. secondary electron steering and focusing voltages, scanned around their corresponding model-optimized values, (2) TOF measurements and resolution and angular resolution, and (3) cross-contamination of the start and stop MCPs' singles rates from CoDICE-Lo and -Hi, and (4) energy resolution of avalanche photodiodes near the lower end of the CoDICE-Lo energy range. We also discuss physical effects that could impact the performance of the TOF vs. E subsystem in a flight instrument. Finally, we discuss advantages of the CoDICE design concept by comparing with capabilities and resources of existing flight instruments.

An integrated time-of-flight versus residual energy subsystem for a compact dual ion composition experiment for space plasmas.

PubMed

Desai, M I; Ogasawara, K; Ebert, R W; McComas, D J; Allegrini, F; Weidner, S E; Alexander, N; Livi, S A

2015-05-01

We have developed a novel concept for a Compact Dual Ion Composition Experiment (CoDICE) that simultaneously provides high quality plasma and energetic ion composition measurements over 6 decades in ion energy in a wide variety of space plasma environments. CoDICE measures the two critical ion populations in space plasmas: (1) mass and ionic charge state composition and 3D velocity and angular distributions of ∼10 eV/q-40 keV/q plasma ions—CoDICE-Lo and (2) mass composition, energy spectra, and angular distributions of ∼30 keV-10 MeV energetic ions—CoDICE-Hi. CoDICE uses a common, integrated Time-of-Flight (TOF) versus residual energy (E) subsystem for measuring the two distinct ion populations. This paper describes the CoDICE design concept, and presents results of the laboratory tests of the TOF portion of the TOF vs. E subsystem, focusing specifically on (1) investigation of spill-over and contamination rates on the start and stop microchannel plate (MCP) anodes vs. secondary electron steering and focusing voltages, scanned around their corresponding model-optimized values, (2) TOF measurements and resolution and angular resolution, and (3) cross-contamination of the start and stop MCPs' singles rates from CoDICE-Lo and -Hi, and (4) energy resolution of avalanche photodiodes near the lower end of the CoDICE-Lo energy range. We also discuss physical effects that could impact the performance of the TOF vs. E subsystem in a flight instrument. Finally, we discuss advantages of the CoDICE design concept by comparing with capabilities and resources of existing flight instruments.

Redundancy Technology With A Focused Ion Beam

NASA Astrophysics Data System (ADS)

Komano, Haruki; Hashimoto, Kazuhiko; Takigawa, Tadahiro

1989-08-01

Fuse cutting with a focused ion beam to activate redundancy circuits is proposed. In order to verify its potential usefulness, experiments have been performed. Fuse-cutting time was evaluated using aluminum fuses with a thin passivation layer, which are difficult to cut by conventional laser-beam technology due to the material's high reflectivity. The fuse width and thickness were 2 and 0.8 μm, respectively. The fuse was cut in 5 seconds with a 30 keV focused ion beam of 0.3 A/cm2 current density. Since the fuses used in DRAMs will be smaller, their cutting time will become shorter by scanning an ion beam on narrower areas. Moreover, it can be shortened by increasing current density. Fuses for redundancy technology in 256 k CMOS SRAMs were cut with a focused ion beam. The operation of the memories was checked with a memory tester. It was confirmed that memories which had failure cells operated normally after focused-ion-beam fuse-cutting. Focused ion beam irradiation effects upon a device have been studied. When a 30 keV gallium focused ion beam was irradiated near the gate of MOSFETs, a threshold voltage shift was not observed at an ion dose of 0.3 C/cm2 which corresponded to the ion dose in cutting a fuse. However, when irradiated on the gate, a threshold voltage shift was observed at ion doses of more than 8 x 10-4 C/cm2. The voltage shift was caused by the charge of ions within the passivation layer. It is necessary at least not to irradiate a focused ion beam on a device in cutting fuses. It is concluded that the focused-ion-beam method will be advantageous for future redundancy technology application.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Desai, M. I.; McComas, D. J.; Allegrini, F.

We have developed a novel concept for a Compact Dual Ion Composition Experiment (CoDICE) that simultaneously provides high quality plasma and energetic ion composition measurements over 6 decades in ion energy in a wide variety of space plasma environments. CoDICE measures the two critical ion populations in space plasmas: (1) mass and ionic charge state composition and 3D velocity and angular distributions of ∼10 eV/q–40 keV/q plasma ions—CoDICE-Lo and (2) mass composition, energy spectra, and angular distributions of ∼30 keV–10 MeV energetic ions—CoDICE-Hi. CoDICE uses a common, integrated Time-of-Flight (TOF) versus residual energy (E) subsystem for measuring the two distinctmore » ion populations. This paper describes the CoDICE design concept, and presents results of the laboratory tests of the TOF portion of the TOF vs. E subsystem, focusing specifically on (1) investigation of spill-over and contamination rates on the start and stop microchannel plate (MCP) anodes vs. secondary electron steering and focusing voltages, scanned around their corresponding model-optimized values, (2) TOF measurements and resolution and angular resolution, and (3) cross-contamination of the start and stop MCPs’ singles rates from CoDICE-Lo and -Hi, and (4) energy resolution of avalanche photodiodes near the lower end of the CoDICE-Lo energy range. We also discuss physical effects that could impact the performance of the TOF vs. E subsystem in a flight instrument. Finally, we discuss advantages of the CoDICE design concept by comparing with capabilities and resources of existing flight instruments.« less

Roles of surface chemistry on safety and electrochemistry in lithium ion batteries.

PubMed

Lee, Kyu Tae; Jeong, Sookyung; Cho, Jaephil

2013-05-21

Motivated by new applications including electric vehicles and the smart grid, interest in advanced lithium ion batteries has increased significantly over the past decade. Therefore, research in this field has intensified to produce safer devices with better electrochemical performance. Most research has focused on the development of new electrode materials through the optimization of bulk properties such as crystal structure, ionic diffusivity, and electric conductivity. More recently, researchers have also considered the surface properties of electrodes as critical factors for optimizing performance. In particular, the electrolyte decomposition at the electrode surface relates to both a lithium ion battery's electrochemical performance and safety. In this Account, we give an overview of the major developments in the area of surface chemistry for lithium ion batteries. These ideas will provide the basis for the design of advanced electrode materials. Initially, we present a brief background to lithium ion batteries such as major chemical components and reactions that occur in lithium ion batteries. Then, we highlight the role of surface chemistry in the safety of lithium ion batteries. We examine the thermal stability of cathode materials: For example, we discuss the oxygen generation from cathode materials and describe how cells can swell and heat up in response to specific conditions. We also demonstrate how coating the surfaces of electrodes can improve safety. The surface chemistry can also affect the electrochemistry of lithium ion batteries. The surface coating strategy improved the energy density and cycle performance for layered LiCoO2, xLi2MnO3·(1 - x)LiMO2 (M = Mn, Ni, Co, and their combinations), and LiMn2O4 spinel materials, and we describe a working mechanism for these enhancements. Although coating the surfaces of cathodes with inorganic materials such as metal oxides and phosphates improves the electrochemical performance and safety properties of batteries, the microstructure of the coating layers and the mechanism of action are not fully understood. Therefore, researchers will need to further investigate the surface coating strategy during the development of new lithium ion batteries.

Xenon gas field ion source from a single-atom tip

NASA Astrophysics Data System (ADS)

Lai, Wei-Chiao; Lin, Chun-Yueh; Chang, Wei-Tse; Li, Po-Chang; Fu, Tsu-Yi; Chang, Chia-Seng; Tsong, T. T.; Hwang, Ing-Shouh

2017-06-01

Focused ion beam (FIB) systems have become powerful diagnostic and modification tools for nanoscience and nanotechnology. Gas field ion sources (GFISs) built from atomic-size emitters offer the highest brightness among all ion sources and thus can improve the spatial resolution of FIB systems. Here we show that the Ir/W(111) single-atom tip (SAT) can emit high-brightness Xe+ ion beams with a high current stability. The ion emission current versus extraction voltage was analyzed from 150 K up to 309 K. The optimal emitter temperature for maximum Xe+ ion emission was ˜150 K and the reduced brightness at the Xe gas pressure of 1 × 10-4 torr is two to three orders of magnitude higher than that of a Ga liquid metal ion source, and four to five orders of magnitude higher than that of a Xe inductively coupled plasma ion source. Most surprisingly, the SAT emitter remained stable even when operated at 309 K. Even though the ion current decreased with increasing temperature, the current at room temperature (RT) could still reach over 1 pA when the gas pressure was higher than 1 × 10-3 torr, indicating the feasibility of RT-Xe-GFIS for application to FIB systems. The operation temperature of Xe-SAT-GFIS is considerably higher than the cryogenic temperature required for the helium ion microscope (HIM), which offers great technical advantages because only simple or no cooling schemes can be adopted. Thus, Xe-GFIS-FIB would be easy to implement and may become a powerful tool for nanoscale milling and secondary ion mass spectroscopy.

Progress toward a practical laser driven ion source using variable thickness liquid crystal targets

NASA Astrophysics Data System (ADS)

Poole, Patrick; Cochran, Ginevra; Zeil, Karl; Metzkes, Josephine; Obst, Lieselotte; Kluge, Thomas; Schlenvoigt, Hans-Peter; Prencipe, Irene; Cowan, Tom; Schramm, Uli; Schumacher, Douglass

2016-10-01

Ion acceleration from ultra-intense laser interaction has been long investigated in pursuit of requisite energies and spectral distributions for applications like proton cancer therapy. However, the details of ion acceleration mechanisms and their laser intensity scaling are not fully understood, especially the complete role of pulse contrast and target thickness. Additionally, target delivery and alignment at appropriate rates for study and subsequent treatment pose significant challenges. We present results from a campaign on the Draco laser using liquid crystal targets that have on-demand, in-situ thickness tunability over more than three orders of magnitude, enabling rapid data collection due to <1 minute, automatically aligned target formation. Diagnostics include spectral and spatial measurement of ions, electrons, and reflected and transmitted light, all with thickness, laser focus, and pulse contrast variations. In particular we discuss optimal thickness vs. contrast and details of ultra-thin target normal ion acceleration, along with supporting particle-in-cell studies. This work was supported by the DARPA PULSE program through AMRDEC, by the NNSA (DE-NA0001976), by EC Horizon 2020 LASERLAB-EUROPE/LEPP (654148), and by the German Federal Ministry of Education and Research (BMBF, 03Z1O511).

Irradiation of Materials using Short, Intense Ion Beams

NASA Astrophysics Data System (ADS)

Seidl, Peter; Ji, Q.; Persaud, A.; Feinberg, E.; Silverman, M.; Sulyman, A.; Waldron, W. L.; Schenkel, T.; Barnard, J. J.; Friedman, A.; Grote, D. P.; Gilson, E. P.; Kaganovich, I. D.; Stepanov, A.; Zimmer, M.

2016-10-01

We present experiments studying material properties created with nanosecond and millimeter-scale ion beam pulses on the Neutralized Drift Compression Experiment-II at Berkeley Lab. The explored scientific topics include the dynamics of ion induced damage in materials, materials synthesis far from equilibrium, warm dense matter and intense beam-plasma physics. We describe the improved accelerator performance, diagnostics and results of beam-induced irradiation of thin samples of, e.g., tin and silicon. Bunches with >3x1010 ions/pulse with 1-mm radius and 2-30 ns FWHM duration and have been created. To achieve the short pulse durations and mm-scale focal spot radii, the 1.2 MeV He+ ion beam is neutralized in a drift compression section which removes the space charge defocusing effect during the final compression and focusing. Quantitative comparison of detailed particle-in-cell simulations with the experiment play an important role in optimizing the accelerator performance and keep pace with the accelerator repetition rate of <1/minute. This work was supported by the Office of Science of the US Department of Energy under contracts DE-AC0205CH11231 (LBNL), DE-AC52-07NA27344 (LLNL) and DE-AC02-09CH11466 (PPPL).

Model-Based Battery Management Systems: From Theory to Practice

NASA Astrophysics Data System (ADS)

Pathak, Manan

Lithium-ion batteries are now extensively being used as the primary storage source. Capacity and power fade, and slow recharging times are key issues that restrict its use in many applications. Battery management systems are critical to address these issues, along with ensuring its safety. This dissertation focuses on exploring various control strategies using detailed physics-based electrochemical models developed previously for lithium-ion batteries, which could be used in advanced battery management systems. Optimal charging profiles for minimizing capacity fade based on SEI-layer formation are derived and the benefits of using such control strategies are shown by experimentally testing them on a 16 Ah NMC-based pouch cell. This dissertation also explores different time-discretization strategies for non-linear models, which gives an improved order of convergence for optimal control problems. Lastly, this dissertation also explores a physics-based model for predicting the linear impedance of a battery, and develops a freeware that is extremely robust and computationally fast. Such a code could be used for estimating transport, kinetic and material properties of the battery based on the linear impedance spectra.

Demonstration of a focused ion-beam cross-sectioning technique for ultrastructural examination of resin-dentin interfaces.

PubMed

Van Meerbeek, B; Conn, L J; Duke, E S; Schraub, D; Ghafghaichi, F

1995-03-01

focused ion-beam (FIB) etching, commonly used as a cross-sectioning technique for failure analysis of semiconductor devices, has recently been applied to biological tissues to expose their ultrastructure for examination. It was the aim of this investigation to determine the practical utility of FIB to cross-section resin-dentin interfaces in order to morphologically evaluate the completeness of resin penetration into the exposed collagen scaffold at the resin-dentin bond interface. Two representative commercially available dentin adhesive systems were bonded to mid-coronal dentin. After appropriate fixation and dehydration of the resin-bonded dentin samples, a scanned focused ion-beam of a few tens of nano-meters in diameter was used to cross=section the resin-dentin interface. Examination of the interfacial ultrastructure was accomplished using a field-emission SEM. Results indicate possible artifact production at the cross-sectioned interface, hiding its actual ultrastructure, probably due to a heat-effect with possible recrystallization. Further studies of FIB are needed to optimize its usefulness for resin-dentin interface examinations and other biological tissue applications. Complete resin saturation of the demineralized dentin surface-layer has been claimed to be the key factor for a long-lasting resin-dentin bond. A "clean" artifact-free micro-cross-sectioning technique may provide indisputable ultra-structural information about the depth of resin penetration into the demineralized zone. Such a test would be useful in the development of dentin adhesive systems.

Advanced Characterization Techniques for Sodium-Ion Battery Studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shadike, Zulipiya; Zhao, Enyue; Zhou, Yong-Ning

Sodium (Na)-ion batteries (NIBs) are considered promising alternative candidates to the well-commercialized lithium-ion batteries, especially for applications in large-scale energy storage systems. The electrochemical performance of NIBs such as the cyclability, rate capability, and voltage profiles are strongly dependent on the structural and morphological evolution, phase transformation, sodium-ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling. Therefore, in-depth understanding of the structure and kinetics of electrode materials and the electrode/electrolyte interfaces is essential for optimizing current NIB systems and exploring new materials for NIBs. Recently, rapid progress and development in spectroscopic, microscopic, and scattering techniques have provided extensive insight intomore » the nature of structural evolution, morphological changes of electrode materials, and electrode/electrolyte interface in NIBs. Here in this review, a comprehensive overview of both static (ex situ) and real-time (in situ or in operando) techniques for studying the NIBs is provided. Lastly, special focus is placed on how these techniques are applied to the fundamental investigation of NIB systems and what important results are obtained.« less

Advanced Characterization Techniques for Sodium-Ion Battery Studies

DOE PAGES

Shadike, Zulipiya; Zhao, Enyue; Zhou, Yong-Ning; ...

2018-02-19

Sodium (Na)-ion batteries (NIBs) are considered promising alternative candidates to the well-commercialized lithium-ion batteries, especially for applications in large-scale energy storage systems. The electrochemical performance of NIBs such as the cyclability, rate capability, and voltage profiles are strongly dependent on the structural and morphological evolution, phase transformation, sodium-ion diffusion, and electrode/electrolyte interface reconstruction during charge–discharge cycling. Therefore, in-depth understanding of the structure and kinetics of electrode materials and the electrode/electrolyte interfaces is essential for optimizing current NIB systems and exploring new materials for NIBs. Recently, rapid progress and development in spectroscopic, microscopic, and scattering techniques have provided extensive insight intomore » the nature of structural evolution, morphological changes of electrode materials, and electrode/electrolyte interface in NIBs. Here in this review, a comprehensive overview of both static (ex situ) and real-time (in situ or in operando) techniques for studying the NIBs is provided. Lastly, special focus is placed on how these techniques are applied to the fundamental investigation of NIB systems and what important results are obtained.« less

Distribution uniformity of laser-accelerated proton beams

NASA Astrophysics Data System (ADS)

Zhu, Jun-Gao; Zhu, Kun; Tao, Li; Xu, Xiao-Han; Lin, Chen; Ma, Wen-Jun; Lu, Hai-Yang; Zhao, Yan-Ying; Lu, Yuan-Rong; Chen, Jia-Er; Yan, Xue-Qing

2017-09-01

Compared with conventional accelerators, laser plasma accelerators can generate high energy ions at a greatly reduced scale, due to their TV/m acceleration gradient. A compact laser plasma accelerator (CLAPA) has been built at the Institute of Heavy Ion Physics at Peking University. It will be used for applied research like biological irradiation, astrophysics simulations, etc. A beamline system with multiple quadrupoles and an analyzing magnet for laser-accelerated ions is proposed here. Since laser-accelerated ion beams have broad energy spectra and large angular divergence, the parameters (beam waist position in the Y direction, beam line layout, drift distance, magnet angles etc.) of the beamline system are carefully designed and optimised to obtain a radially symmetric proton distribution at the irradiation platform. Requirements of energy selection and differences in focusing or defocusing in application systems greatly influence the evolution of proton distributions. With optimal parameters, radially symmetric proton distributions can be achieved and protons with different energy spread within ±5% have similar transverse areas at the experiment target. Supported by National Natural Science Foundation of China (11575011, 61631001) and National Grand Instrument Project (2012YQ030142)

ION BEAM FOCUSING MEANS FOR CALUTRON

DOEpatents

Backus, J.G.

1959-06-01

An ion beam focusing arrangement for calutrons is described. It provides a virtual focus of origin for the ion beam so that the ions may be withdrawn from an arc plasma of considerable width providing greater beam current and accuracy. (T.R.H.)

Optimized Li-Ion Electrolytes Containing Fluorinated Ester Co-Solvents

NASA Technical Reports Server (NTRS)

Prakash, G. K. Surya; Smart, Marshall; Smith, Kiah; Bugga, Ratnakumar

2010-01-01

A number of experimental lithium-ion cells, consisting of MCMB (meso-carbon microbeads) carbon anodes and LiNi(0.8)Co(0.2)O2 cathodes, have been fabricated with increased safety and expanded capability. These cells serve to verify and demonstrate the reversibility, low-temperature performance, and electrochemical aspects of each electrode as determined from a number of electrochemical characterization techniques. A number of Li-ion electrolytes possessing fluorinated ester co-solvents, namely trifluoroethyl butyrate (TFEB) and trifluoroethyl propionate (TFEP), were demonstrated to deliver good performance over a wide temperature range in experimental lithium-ion cells. The general approach taken in the development of these electrolyte formulations is to optimize the type and composition of the co-solvents in ternary and quaternary solutions, focusing upon adequate stability [i.e., EC (ethylene carbonate) content needed for anode passivation, and EMC (ethyl methyl carbonate) content needed for lowering the viscosity and widening the temperature range, while still providing good stability], enhancing the inherent safety characteristics (incorporation of fluorinated esters), and widening the temperature range of operation (the use of both fluorinated and non-fluorinated esters). Further - more, the use of electrolyte additives, such as VC (vinylene carbonate) [solid electrolyte interface (SEI) promoter] and DMAc (thermal stabilizing additive), provide enhanced high-temperature life characteristics. Multi-component electrolyte formulations enhance performance over a temperature range of -60 to +60 C. With the need for more safety with the use of these batteries, flammability was a consideration. One of the solvents investigated, TFEB, had the best performance with improved low-temperature capability and high-temperature resilience. This work optimized the use of TFEB as a co-solvent by developing the multi-component electrolytes, which also contain non-halogenated esters, film forming additives, thermal stabilizing additives, and flame retardant additives. Further optimization of these electrolyte formulations is anticipated to yield improved performance. It is also anticipated that much improved performance will be demonstrated once these electrolyte solutions are incorporated into hermetically sealed, large capacity prototype cells, especially if effort is devoted to ensure that all electrolyte components are highly pure.

Improved transmission of electrostatic accelerator in a wide range of terminal voltages by controlling the focal strength of entrance acceleration tube

NASA Astrophysics Data System (ADS)

Lobanov, Nikolai R.; Tunningley, Thomas; Linardakis, Peter

2018-04-01

Tandem electrostatic accelerators often require the flexibility to operate at a variety of terminal voltages to accommodate various user requirements. However, the ion beam transmission will only be optimal for a limited range of terminal voltages. This paper describes the operational performance of a novel focusing system that expands the range of terminal voltages for optimal transmission. This is accomplished by controlling the gradient of the entrance of the low-energy tube, providing an additional focusing element. In this specific case it is achieved by applying up to 150 kV to the fifth electrode of the first unit of the accelerator tube. Numerical simulations and beam transmission tests have been performed to confirm the effectiveness of the lens. An analytical expression has been derived describing its focal properties. These tests demonstrate that the entrance lens control eliminates the need to short out sections of the tube for operation at low terminal voltage.

Development of the dense plasma focus for short-pulse applications

NASA Astrophysics Data System (ADS)

Bennett, N.; Blasco, M.; Breeding, K.; Constantino, D.; DeYoung, A.; DiPuccio, V.; Friedman, J.; Gall, B.; Gardner, S.; Gatling, J.; Hagen, E. C.; Luttman, A.; Meehan, B. T.; Misch, M.; Molnar, S.; Morgan, G.; O'Brien, R.; Robbins, L.; Rundberg, R.; Sipe, N.; Welch, D. R.; Yuan, V.

2017-01-01

The dense plasma focus (DPF) has long been considered a compact source for pulsed neutrons and has traditionally been optimized for the total neutron yield. In this paper, we describe the efforts to optimize the DPF for short-pulse applications by introducing a reentrant cathode at the end of the coaxial plasma gun. The resulting neutron pulse widths are reduced by an average of 21 ±9 % from the traditional long-drift DPF design. Pulse widths and yields achieved from deuterium-tritium fusion at 2 MA are 61.8 ±30.7 ns FWHM and 1.84 ±0.49 ×1012 neutrons per shot. Simulations were conducted concurrently to elucidate the DPF operation and confirm the role of the reentrant cathode. A hybrid fluid-kinetic particle-in-cell modeling capability demonstrates correct sheath velocities, plasma instabilities, and fusion yield rates. Consistent with previous findings that the DPF is dominated by beam-target fusion from superthermal ions, we estimate that the thermonuclear contribution is at the 1% level.

Bioregenerative life support systems for microgravity

NASA Technical Reports Server (NTRS)

Nevill, Gail E., Jr.; Hessel, Michael I., Jr.; Rodriguez, Jose; Morgan, Steve (Editor)

1993-01-01

NASA's Controlled Ecological Life Support System (CELSS) project centers on growing plants and recycling wastes in space. The current version of the biomass production chamber (BPC) uses a hydroponic system for nutrient delivery. To optimize plant growth and conserve system resources, the content of the nutrient solution which feeds the plants must be constantly monitored. The macro-nutrients (greater than ten ppm) in the solution include nitrogen, phosphorous, potassium, calcium, magnesium, and sulphur; the micro-nutrients (less than ten ppm) include iron, copper, manganese, zinc, and boron. The goal of this project is to construct a computer-controlled system of ion detectors that will accurately measure the concentrations of several necessary ions in solution. The project focuses on the use of a sensor array to eliminate problems of interference and temperature dependence.

Advances in organic polymer-based monolithic column technology for high-resolution liquid chromatography-mass spectrometry profiling of antibodies, intact proteins, oligonucleotides, and peptides.

PubMed

Eeltink, Sebastiaan; Wouters, Sam; Dores-Sousa, José Luís; Svec, Frantisek

2017-05-19

This review focuses on the preparation of organic polymer-based monolithic stationary phases and their application in the separation of biomolecules, including antibodies, intact proteins and protein isoforms, oligonucleotides, and protein digests. Column and material properties, and the optimization of the macropore structure towards kinetic performance are also discussed. State-of-the-art liquid chromatography-mass spectrometry biomolecule separations are reviewed and practical aspects such as ion-pairing agent selection and carryover are presented. Finally, advances in comprehensive two-dimensional LC separations using monolithic columns, in particular ion-exchange×reversed-phase and reversed-phase×reversed-phase LC separations conducted at high and low pH, are shown. Copyright © 2017 Elsevier B.V. All rights reserved.

Two novel approaches to study arthropod anatomy by using dualbeam FIB/SEM.

PubMed

Di Giulio, Andrea; Muzzi, Maurizio

2018-03-01

Transmission Electron Microscopy (TEM) has always been the conventional method to study arthropod ultrastructure, while the use of Scanning Electron Microscopy (SEM) was mainly devoted to the examination of the external cuticular structures by secondary electrons. The new generation field emission SEMs are capable to generate images at sub-cellular level, comparable to TEM images employing backscattered electrons. The potential of this kind of acquisition becomes very powerful in the dual beam FIB/SEM where the SEM column is combined with a Focused Ion Beam (FIB) column. FIB uses ions as a nano-scalpel to slice samples fixed and embedded in resin, replacing traditional ultramicrotomy. We here present two novel methods, which optimize the use of FIB/SEM for studying arthropod anatomy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advanced analytical electron microscopy for alkali-ion batteries

DOE PAGES

Qian, Danna; Ma, Cheng; Meng, Ying Shirley; ...

2015-06-26

Lithium-ion batteries are a leading candidate for electric vehicle and smart grid applications. However, further optimizations of the energy/power density, coulombic efficiency and cycle life are still needed, and this requires a thorough understanding of the dynamic evolution of each component and their synergistic behaviors during battery operation. With the capability of resolving the structure and chemistry at an atomic resolution, advanced analytical transmission electron microscopy (AEM) is an ideal technique for this task. The present review paper focuses on recent contributions of this important technique to the fundamental understanding of the electrochemical processes of battery materials. A detailed reviewmore » of both static (ex situ) and real-time (in situ) studies will be given, and issues that still need to be addressed will be discussed.« less

Ionic force field optimization based on single-ion and ion-pair solvation properties: Going beyond standard mixing rules

NASA Astrophysics Data System (ADS)

Fyta, Maria; Netz, Roland R.

2012-03-01

Using molecular dynamics (MD) simulations in conjunction with the SPC/E water model, we optimize ionic force-field parameters for seven different halide and alkali ions, considering a total of eight ion-pairs. Our strategy is based on simultaneous optimizing single-ion and ion-pair properties, i.e., we first fix ion-water parameters based on single-ion solvation free energies, and in a second step determine the cation-anion interaction parameters (traditionally given by mixing or combination rules) based on the Kirkwood-Buff theory without modification of the ion-water interaction parameters. In doing so, we have introduced scaling factors for the cation-anion Lennard-Jones (LJ) interaction that quantify deviations from the standard mixing rules. For the rather size-symmetric salt solutions involving bromide and chloride ions, the standard mixing rules work fine. On the other hand, for the iodide and fluoride solutions, corresponding to the largest and smallest anion considered in this work, a rescaling of the mixing rules was necessary. For iodide, the experimental activities suggest more tightly bound ion pairing than given by the standard mixing rules, which is achieved in simulations by reducing the scaling factor of the cation-anion LJ energy. For fluoride, the situation is different and the simulations show too large attraction between fluoride and cations when compared with experimental data. For NaF, the situation can be rectified by increasing the cation-anion LJ energy. For KF, it proves necessary to increase the effective cation-anion Lennard-Jones diameter. The optimization strategy outlined in this work can be easily adapted to different kinds of ions.

Transport of Helium Pickup Ions within the Focusing Cone: Reconciling STEREO Observations with IBEX

NASA Astrophysics Data System (ADS)

Quinn, P. R.; Schwadron, N. A.; Möbius, E.

2016-06-01

Recent observations of the pickup helium focusing cone by STEREO/Plasma and Suprathermal Ion Composition indicate an inflow longitude of the interstellar wind that differs from the observations of IBEX by 1\\buildrel{\\circ}\\over{.} 8+/- 2\\buildrel{\\circ}\\over{.} 4. It has been under debate whether the transport of helium pickup ions with an anisotropic velocity distribution is the cause of this difference. If so, the roughly field-aligned pickup ion streaming relative to the solar wind should create a shift in the pickup ion density relative to the focusing cone. A large pickup ion streaming depends on the size of the mean free path. Therefore, the observed longitudinal shift in the pickup ion density relative to the neutral focusing cone may carry fundamental information about the mean free path experienced by pickup ions inside 1 au. We test this hypothesis using the Energetic Particle Radiation Environment Module (EPREM) model by simulating the transport of helium pickup ions within the focusing cone finding a mean free path of {λ }\\parallel =0.19+0.29(-0.19) au. We calculate the average azimuthal velocity of pickup ions and find that the anisotropic distribution reaches ˜8% of the solar wind speed. Lastly, we isolate transport effects within EPREM, finding that pitch-angle scattering, adiabatic focusing, perpendicular diffusion, and particle drift contribute to shifting the focusing cone 20.00%, 69.43%, 10.56%, and \\lt 0.01 % , respectively. Thus we show with the EPREM model that the transport of pickup ions does indeed shift the peak of the focusing cone relative to the progenitor neutral atoms and this shift provides fundamental information on the scattering of pickup ions inside 1 au.

Hybrid quadrupole mass filter/quadrupole ion trap/time-of-flight-mass spectrometer for infrared multiple photon dissociation spectroscopy of mass-selected ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gulyuz, Kerim; Stedwell, Corey N.; Wang Da

2011-05-15

We present a laboratory-constructed mass spectrometer optimized for recording infrared multiple photon dissociation (IRMPD) spectra of mass-selected ions using a benchtop tunable infrared optical parametric oscillator/amplifier (OPO/A). The instrument is equipped with two ionization sources, an electrospray ionization source, as well as an electron ionization source for troubleshooting. This hybrid mass spectrometer is composed of a quadrupole mass filter for mass selection, a reduced pressure ({approx}10{sup -5} Torr) quadrupole ion trap (QIT) for OPO irradiation, and a reflectron time-of-flight drift tube for detecting the remaining precursor and photofragment ions. A helium gas pulse is introduced into the QIT to temporarilymore » increase the pressure and hence enhance the trapping efficiency of axially injected ions. After a brief pump-down delay, the compact ion cloud is subjected to the focused output from the continuous wave OPO. In a recent study, we implemented this setup in the study of protonated tryptophan, TrpH{sup +}, as well as collision-induced dissociation products of this protonated amino acid [W. K. Mino, Jr., K. Gulyuz, D. Wang, C. N. Stedwell, and N. C. Polfer, J. Phys. Chem. Lett. 2, 299 (2011)]. Here, we give a more detailed account on the figures of merit of such IRMPD experiments. The appreciable photodissociation yields in these measurements demonstrate that IRMPD spectroscopy of covalently bound ions can be routinely carried out using benchtop OPO setups.« less

Control of average spacing of OMCVD grown gold nanoparticles

NASA Astrophysics Data System (ADS)

Rezaee, Asad

Metallic nanostructures and their applications is a rapidly expanding field. Nobel metals such as silver and gold have historically been used to demonstrate plasmon effects due to their strong resonances, which occur in the visible part of the electromagnetic spectrum. Localized surface plasmon resonance (LSPR) produces an enhanced electromagnetic field at the interface between a gold nanoparticle (Au NP) and the surrounding dielectric. This enhanced field can be used for metal-dielectric interfacesensitive optical interactions that form a powerful basis for optical sensing. In addition to the surrounding material, the LSPR spectral position and width depend on the size, shape, and average spacing between these particles. Au NP LSPR based sensors depict their highest sensitivity with optimized parameters and usually operate by investigating absorption peak: shifts. The absorption peak: of randomly deposited Au NPs on surfaces is mostly broad. As a result, the absorption peak: shifts, upon binding of a material onto Au NPs might not be very clear for further analysis. Therefore, novel methods based on three well-known techniques, self-assembly, ion irradiation, and organo-meta1lic chemical vapour deposition (OMCVD) are introduced to control the average-spacing between Au NPs. In addition to covalently binding and other advantages of OMCVD grown Au NPs, interesting optical features due to their non-spherical shapes are presented. The first step towards the average-spacing control is to uniformly form self-assembled monolayers (SAMs) of octadecyltrichlorosilane (OTS) as resists for OMCVD Au NPs. The formation and optimization of the OTS SAMs are extensively studied. The optimized resist SAMs are ion-irradiated by a focused ion beam (Fill) and ions generated by a Tandem accelerator. The irradiated areas are refilled with 3-mercaptopropyl-trimethoxysilane (MPTS) to provide nucleation sites for the OMCVD Au NP growth. Each step during sample preparation is monitored by using surface characterization methods such as contact angle measurements, ellipsometry, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), Rutherford backscattering spectroscopy (RBS), UV-Visible spectroscopy, and time-of-flight secondary ion mass spectroscopy (ToF-SIMS). Keywords: Absorption, Array, Average Spacing, Binary Mixture, Density, Deposition, Dose, Fm, Gold Nanoparticle, Growth, Ion Irradiation, LSPR, Nanolithography, Nearest Neighbour Distance, OMCVD, Optical Response, OTS, Polarization, Refilling, Resist, SAM, Self-assembly, SEM Image Analysis, Sensing, Surface, Thin Film, Transparent Substrate.

A multi-plate velocity-map imaging design for high-resolution photoelectron spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kregel, Steven J.; Thurston, Glen K.; Zhou, Jia

A velocity map imaging (VMI) setup consisting of multiple electrodes with three adjustable voltage parameters, designed for slow electron velocity map imaging applications, is presented. The motivations for this design are discussed in terms of parameters that influence the VMI resolution and functionality. Particularly, this VMI has two tunable potentials used to adjust for optimal focus, yielding good VMI focus across a relatively large energy range. It also allows for larger interaction volumes without significant sacrifice to the resolution via a smaller electric gradient at the interaction region. All the electrodes in this VMI have the same dimensions for practicalitymore » and flexibility, allowing for relatively easy modifications to suit different experimental needs. We have coupled this VMI to a cryogenic ion trap mass spectrometer that has a flexible source design. The performance is demonstrated with the photoelectron spectra of S- and CS 2 -. The latter has a long vibrational progression in the ground state, and the temperature dependence of the vibronic features is probed by changing the temperature of the ion trap.« less

Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy

PubMed Central

HÖHN, K.; FUCHS, J.; FRÖBER, A.; KIRMSE, R.; GLASS, B.; ANDERS‐ÖSSWEIN, M.; WALTHER, P.; KRÄUSSLICH, H.‐G.

2015-01-01

Summary In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV‐pulsed mature human dendritic cells. PMID:25786567

A multi-plate velocity-map imaging design for high-resolution photoelectron spectroscopy

DOE PAGES

Kregel, Steven J.; Thurston, Glen K.; Zhou, Jia; ...

2017-09-01

A velocity map imaging (VMI) setup consisting of multiple electrodes with three adjustable voltage parameters, designed for slow electron velocity map imaging applications, is presented. The motivations for this design are discussed in terms of parameters that influence the VMI resolution and functionality. Particularly, this VMI has two tunable potentials used to adjust for optimal focus, yielding good VMI focus across a relatively large energy range. It also allows for larger interaction volumes without significant sacrifice to the resolution via a smaller electric gradient at the interaction region. All the electrodes in this VMI have the same dimensions for practicalitymore » and flexibility, allowing for relatively easy modifications to suit different experimental needs. We have coupled this VMI to a cryogenic ion trap mass spectrometer that has a flexible source design. The performance is demonstrated with the photoelectron spectra of S- and CS 2 -. The latter has a long vibrational progression in the ground state, and the temperature dependence of the vibronic features is probed by changing the temperature of the ion trap.« less

Advanced Design Concepts for Dense Plasma Focus Devices at LLNL

NASA Astrophysics Data System (ADS)

Povilus, Alexander; Podpaly, Yuri; Cooper, Christopher; Shaw, Brian; Chapman, Steve; Mitrani, James; Anderson, Michael; Pearson, Aric; Anaya, Enrique; Koh, Ed; Falabella, Steve; Link, Tony; Schmidt, Andrea

2017-10-01

The dense plasma focus (DPF) is a z-pinch device where a plasma sheath is accelerated down a coaxial railgun and ends in a radial implosion, pinch phase. During the pinch phase, the plasma generates intense, transient electric fields through physical mechanisms, similar to beam instabilities, that can accelerate ions in the plasma sheath to MeV-scale energies on millimeter length scales. Using kinetic modeling techniques developed at LLNL, we have gained insight into the formation of these accelerating fields and are using these observations to optimize the behavior of the generated ion beam for producing neutrons via beam-target interactions for kilojoule to megajoule-scale devices. Using a set of DPF's, both in operation and in development at LLNL, we have explored critical aspects of these devices, including plasma sheath formation behavior, power delivery to the plasma, and instability seeding during the implosion in order to improve the absolute yield and stability of the device. Prepared by LLNL under Contract DE-AC52-07NA27344. Computing support for this work came from the LLNL Institutional Computing Grand Challenge program.

Superconductivity in the system Mo{sub x}C{sub y}Ga{sub z}O{sub δ} prepared by focused ion beam induced deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weirich, P. M., E-mail: p.weirich@Physik.uni-frankfurt.de; Schwalb, C. H.; Winhold, M.

2014-05-07

We have prepared the new amorphous superconductor Mo{sub x}C{sub y}Ga{sub z}O{sub δ} with a maximum critical temperature T{sub c} of 3.8 K by the direct-write nano-patterning technique of focused (gallium) ion beam induced deposition (FIBID) using Mo(CO){sub 6} as precursor gas. From a detailed analysis of the temperature-dependent resistivity and the upper critical field, we found clear evidence for proximity of the samples to a disorder-induced metal-insulator transition. We observed a strong dependence of T{sub c} on the deposition parameters and identified clear correlations between T{sub c}, the localization tendency visible in the resistance data and the sample composition. By anmore » in-situ feedback-controlled optimization process in the FIB-induced growth, we were able to identify the beam parameters which lead to samples with the largest T{sub c}-value and sharpest transition into the superconducting state.« less

Comparisons of dense-plasma-focus kinetic simulations with experimental measurements.

PubMed

Schmidt, A; Link, A; Welch, D; Ellsworth, J; Falabella, S; Tang, V

2014-06-01

Dense-plasma-focus (DPF) Z-pinch devices are sources of copious high-energy electrons and ions, x rays, and neutrons. The mechanisms through which these physically simple devices generate such high-energy beams in a relatively short distance are not fully understood and past optimization efforts of these devices have been largely empirical. Previously we reported on fully kinetic simulations of a DPF and compared them with hybrid and fluid simulations of the same device. Here we present detailed comparisons between fully kinetic simulations and experimental data on a 1.2 kJ DPF with two electrode geometries, including neutron yield and ion beam energy distributions. A more intensive third calculation is presented which examines the effects of a fully detailed pulsed power driver model. We also compare simulated electromagnetic fluctuations with direct measurement of radiofrequency electromagnetic fluctuations in a DPF plasma. These comparisons indicate that the fully kinetic model captures the essential physics of these plasmas with high fidelity, and provide further evidence that anomalous resistivity in the plasma arises due to a kinetic instability near the lower hybrid frequency.

Ion creation, ion focusing, ion/molecule reactions, ion separation, and ion detection in the open air in a small plastic device.

PubMed

Baird, Zane; Wei, Pu; Cooks, R Graham

2015-02-07

A method is presented in which ions are generated and manipulated in the ambient environment using polymeric electrodes produced with a consumer-grade 3D printer. The ability to focus, separate, react, and detect ions in the ambient environment is demonstrated and the data agree well with simulated ion behaviour.

Improved sliced velocity map imaging apparatus optimized for H photofragments.

PubMed

Ryazanov, Mikhail; Reisler, Hanna

2013-04-14

Time-sliced velocity map imaging (SVMI), a high-resolution method for measuring kinetic energy distributions of products in scattering and photodissociation reactions, is challenging to implement for atomic hydrogen products. We describe an ion optics design aimed at achieving SVMI of H fragments in a broad range of kinetic energies (KE), from a fraction of an electronvolt to a few electronvolts. In order to enable consistently thin slicing for any imaged KE range, an additional electrostatic lens is introduced in the drift region for radial magnification control without affecting temporal stretching of the ion cloud. Time slices of ∼5 ns out of a cloud stretched to ⩾50 ns are used. An accelerator region with variable dimensions (using multiple electrodes) is employed for better optimization of radial and temporal space focusing characteristics at each magnification level. The implemented system was successfully tested by recording images of H fragments from the photodissociation of HBr, H2S, and the CH2OH radical, with kinetic energies ranging from <0.4 eV to >3 eV. It demonstrated KE resolution ≲1%-2%, similar to that obtained in traditional velocity map imaging followed by reconstruction, and to KE resolution achieved previously in SVMI of heavier products. We expect it to perform just as well up to at least 6 eV of kinetic energy. The tests showed that numerical simulations of the electric fields and ion trajectories in the system, used for optimization of the design and operating parameters, provide an accurate and reliable description of all aspects of system performance. This offers the advantage of selecting the best operating conditions in each measurement without the need for additional calibration experiments.

Performance optimization in electric field gradient focusing.

PubMed

Sun, Xuefei; Farnsworth, Paul B; Tolley, H Dennis; Warnick, Karl F; Woolley, Adam T; Lee, Milton L

2009-01-02

Electric field gradient focusing (EFGF) is a technique used to simultaneously separate and concentrate biomacromolecules, such as proteins, based on the opposing forces of an electric field gradient and a hydrodynamic flow. Recently, we reported EFGF devices fabricated completely from copolymers functionalized with poly(ethylene glycol), which display excellent resistance to protein adsorption. However, the previous devices did not provide the predicted linear electric field gradient and stable current. To improve performance, Tris-HCl buffer that was previously doped in the hydrogel was replaced with a phosphate buffer containing a salt (i.e., potassium chloride, KCl) with high mobility ions. The new devices exhibited stable current, good reproducibility, and a linear electric field distribution in agreement with the shaped gradient region design due to improved ion transport in the hydrogel. The field gradient was calculated based on theory to be approximately 5.76 V/cm(2) for R-phycoerythrin when the applied voltage was 500 V. The effect of EFGF separation channel dimensions was also investigated; a narrower focused band was achieved in a smaller diameter channel. The relationship between the bandwidth and channel diameter is consistent with theory. Three model proteins were resolved in an EFGF channel of this design. The improved device demonstrated 14,000-fold concentration of a protein sample (from 2 ng/mL to 27 microg/mL).

Janus: Graphical Software for Analyzing In-Situ Measurements of Solar-Wind Ions

NASA Astrophysics Data System (ADS)

Maruca, B.; Stevens, M. L.; Kasper, J. C.; Korreck, K. E.

2016-12-01

In-situ observations of solar-wind ions provide tremendous insights into the physics of space plasmas. Instrument on spacecraft measure distributions of ion energies, which can be processed into scientifically useful data (e.g., values for ion densities and temperatures). This analysis requires a strong, technical understanding of the instrument, so it has traditionally been carried out by the instrument teams using automated software that they had developed for that purpose. The automated routines are optimized for typical solar-wind conditions, so they can fail to capture the complex (and scientifically interesting) microphysics of transient solar-wind - such as coronal mass ejections (CME's) and co-rotating interaction regions (CIR's) - which are often better analyzed manually.This presentation reports on the ongoing development of Janus, a new software package for processing in-situ measurement of solar-wind ions. Janus will provide user with an easy-to-use graphical user interface (GUI) for carrying out highly customized analyses. Transparent to the user, Janus will automatically handle the most technical tasks (e.g., the retrieval and calibration of measurements). For the first time, users with only limited knowledge about the instruments (e.g., non-instrumentalists and students) will be able to easily process measurements of solar-wind ions. Version 1 of Janus focuses specifically on such measurements from the Wind spacecraft's Faraday Cups and is slated for public release in time for this presentation.

Magnetized retarding field energy analyzer measuring the particle flux and ion energy distribution of both positive and negative ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rafalskyi, Dmytro; Aanesland, Ane; Dudin, Stanislav

2015-05-15

This paper presents the development of a magnetized retarding field energy analyzer (MRFEA) used for positive and negative ion analysis. The two-stage analyzer combines a magnetic electron barrier and an electrostatic ion energy barrier allowing both positive and negative ions to be analyzed without the influence of electrons (co-extracted or created downstream). An optimal design of the MRFEA for ion-ion beams has been achieved by a comparative study of three different MRFEA configurations, and from this, scaling laws of an optimal magnetic field strength and topology have been deduced. The optimal design consists of a uniform magnetic field barrier createdmore » in a rectangular channel and an electrostatic barrier consisting of a single grid and a collector placed behind the magnetic field. The magnetic barrier alone provides an electron suppression ratio inside the analyzer of up to 6000, while keeping the ion energy resolution below 5 eV. The effective ion transparency combining the magnetic and electrostatic sections of the MRFEA is measured as a function of the ion energy. It is found that the ion transparency of the magnetic barrier increases almost linearly with increasing ion energy in the low-energy range (below 200 eV) and saturates at high ion energies. The ion transparency of the electrostatic section is almost constant and close to the optical transparency of the entrance grid. We show here that the MRFEA can provide both accurate ion flux and ion energy distribution measurements in various experimental setups with ion beams or plasmas run at low pressure and with ion energies above 10 eV.« less

Ion focusing

DOEpatents

Cooks, Robert Graham; Baird, Zane; Peng, Wen-Ping

2015-11-10

The invention generally relates to apparatuses for focusing ions at or above ambient pressure and methods of use thereof. In certain embodiments, the invention provides an apparatus for focusing ions that includes an electrode having a cavity, at least one inlet within the electrode configured to operatively couple with an ionization source, such that discharge generated by the ionization source is injected into the cavity of the electrode, and an outlet. The cavity in the electrode is shaped such that upon application of voltage to the electrode, ions within the cavity are focused and directed to the outlet, which is positioned such that a proximal end of the outlet receives the focused ions and a distal end of the outlet is open to ambient pressure.

Ion focusing

DOEpatents

Cooks, Robert Graham; Baird, Zane; Peng, Wen-Ping

2017-01-17

The invention generally relates to apparatuses for focusing ions at or above ambient pressure and methods of use thereof. In certain embodiments, the invention provides an apparatus for focusing ions that includes an electrode having a cavity, at least one inlet within the electrode configured to operatively couple with an ionization source, such that discharge generated by the ionization source is injected into the cavity of the electrode, and an outlet. The cavity in the electrode is shaped such that upon application of voltage to the electrode, ions within the cavity are focused and directed to the outlet, which is positioned such that a proximal end of the outlet receives the focused ions and a distal end of the outlet is open to ambient pressure.

Development of novel purifiers with appropriate functional groups based on solvent polarities at bulk filtration

NASA Astrophysics Data System (ADS)

Kohyama, Tetsu; Kaneko, Fumiya; Ly, Saksatha; Hamzik, James; Jaber, Jad; Yamada, Yoshiaki

2017-03-01

Weak-polar solvents like PGMEA (Propylene Glycol Monomethyl Ether Acetate) or CHN (Cyclohexanone) are used to dissolve hydrophobic photo-resist polymers, which are challenging for traditional cleaning methods such as distillation, ion-exchange resins service or water-washing processes. This paper investigated two novel surface modifications to see their effectiveness at metal removal and to understand the mechanism. The experiments yielded effective purification methods for metal reduction, focusing on solvent polarities based on HSP (Hansen Solubility Parameters), and developing optimal purification strategies.

Inert gas ion source program

NASA Technical Reports Server (NTRS)

Ramsey, W. D.

1978-01-01

THe original 12 cm hexagonal magneto-electrostatic containment discharge chamber has been optimized for argon and xenon operation. Argon mass utilization efficiencies of 65 to 77 percent were achieved at keeper-plus-main discharge energy consumptions of 200 to 458 eV/ion, respectively. Xenon performance of 84 to 96 percent mass utilization was realized at 203 to 350 eV/ion. The optimization process and test results are discussed.

Fast Biological Modeling for Voxel-based Heavy Ion Treatment Planning Using the Mechanistic Repair-Misrepair-Fixation Model and Nuclear Fragment Spectra

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kamp, Florian; Department of Radiation Oncology, Technische Universität München, Klinikum Rechts der Isar, München; Physik-Department, Technische Universität München, Garching

2015-11-01

Purpose: The physical and biological differences between heavy ions and photons have not been fully exploited and could improve treatment outcomes. In carbon ion therapy, treatment planning must account for physical properties, such as the absorbed dose and nuclear fragmentation, and for differences in the relative biological effectiveness (RBE) of ions compared with photons. We combined the mechanistic repair-misrepair-fixation (RMF) model with Monte Carlo-generated fragmentation spectra for biological optimization of carbon ion treatment plans. Methods and Materials: Relative changes in double-strand break yields and radiosensitivity parameters with particle type and energy were determined using the independently benchmarked Monte Carlo damagemore » simulation and the RMF model to estimate the RBE values for primary carbon ions and secondary fragments. Depth-dependent energy spectra were generated with the Monte Carlo code FLUKA for clinically relevant initial carbon ion energies. The predicted trends in RBE were compared with the published experimental data. Biological optimization for carbon ions was implemented in a 3-dimensional research treatment planning tool. Results: We compared the RBE and RBE-weighted dose (RWD) distributions of different carbon ion treatment scenarios with and without nuclear fragments. The inclusion of fragments in the simulations led to smaller RBE predictions. A validation of RMF against measured cell survival data reported in published studies showed reasonable agreement. We calculated and optimized the RWD distributions on patient data and compared the RMF predictions with those from other biological models. The RBE values in an astrocytoma tumor ranged from 2.2 to 4.9 (mean 2.8) for a RWD of 3 Gy(RBE) assuming (α/β){sub X} = 2 Gy. Conclusions: These studies provide new information to quantify and assess uncertainties in the clinically relevant RBE values for carbon ion therapy based on biophysical mechanisms. We present results from the first biological optimization of carbon ion radiation therapy beams on patient data using a combined RMF and Monte Carlo damage simulation modeling approach. The presented method is advantageous for fast biological optimization.« less

Fast Biological Modeling for Voxel-based Heavy Ion Treatment Planning Using the Mechanistic Repair-Misrepair-Fixation Model and Nuclear Fragment Spectra.

PubMed

Kamp, Florian; Cabal, Gonzalo; Mairani, Andrea; Parodi, Katia; Wilkens, Jan J; Carlson, David J

2015-11-01

The physical and biological differences between heavy ions and photons have not been fully exploited and could improve treatment outcomes. In carbon ion therapy, treatment planning must account for physical properties, such as the absorbed dose and nuclear fragmentation, and for differences in the relative biological effectiveness (RBE) of ions compared with photons. We combined the mechanistic repair-misrepair-fixation (RMF) model with Monte Carlo-generated fragmentation spectra for biological optimization of carbon ion treatment plans. Relative changes in double-strand break yields and radiosensitivity parameters with particle type and energy were determined using the independently benchmarked Monte Carlo damage simulation and the RMF model to estimate the RBE values for primary carbon ions and secondary fragments. Depth-dependent energy spectra were generated with the Monte Carlo code FLUKA for clinically relevant initial carbon ion energies. The predicted trends in RBE were compared with the published experimental data. Biological optimization for carbon ions was implemented in a 3-dimensional research treatment planning tool. We compared the RBE and RBE-weighted dose (RWD) distributions of different carbon ion treatment scenarios with and without nuclear fragments. The inclusion of fragments in the simulations led to smaller RBE predictions. A validation of RMF against measured cell survival data reported in published studies showed reasonable agreement. We calculated and optimized the RWD distributions on patient data and compared the RMF predictions with those from other biological models. The RBE values in an astrocytoma tumor ranged from 2.2 to 4.9 (mean 2.8) for a RWD of 3 Gy(RBE) assuming (α/β)X = 2 Gy. These studies provide new information to quantify and assess uncertainties in the clinically relevant RBE values for carbon ion therapy based on biophysical mechanisms. We present results from the first biological optimization of carbon ion radiation therapy beams on patient data using a combined RMF and Monte Carlo damage simulation modeling approach. The presented method is advantageous for fast biological optimization. Copyright © 2015 Elsevier Inc. All rights reserved.

Femtosecond laser machining for characterization of local mechanical properties of biomaterials: a case study on wood

PubMed Central

Jakob, Severin; Pfeifenberger, Manuel J.; Hohenwarter, Anton; Pippan, Reinhard

2017-01-01

Abstract The standard preparation technique for micro-sized samples is focused ion beam milling, most frequently using Ga+ ions. The main drawbacks are the required processing time and the possibility and risks of ion implantation. In contrast, ultrashort pulsed laser ablation can process any type of material with ideally negligible damage to the surrounding volume and provides 4 to 6 orders of magnitude higher ablation rates than the ion beam technique. In this work, a femtosecond laser was used to prepare wood samples from spruce for mechanical testing at the micrometre level. After optimization of the different laser parameters, tensile and compressive specimens were produced from microtomed radial-tangential and longitudinal-tangential sections. Additionally, laser-processed samples were exposed to an electron beam prior to testing to study possible beam damage. The specimens originating from these different preparation conditions were mechanically tested. Advantages and limitations of the femtosecond laser preparation technique and the deformation and fracture behaviour of the samples are discussed. The results prove that femtosecond laser processing is a fast and precise preparation technique, which enables the fabrication of pristine biological samples with dimensions at the microscale. PMID:28970867

Measurement profiles of nano-scale ion beam for optimized radiation energy losses

NASA Astrophysics Data System (ADS)

Woo, T. H.; Cho, H. S.

2011-10-01

The behavior of charged particles is investigated for nano-scale ion beam therapy using a medical accelerator. Computational work is performed for the Bragg-peak simulation, which is focused on human organ material of pancreas and thyroid. The Results show that the trends of the dose have several different kinds of distributions. Before constructing a heavy ion collider, this study can give us the reliability of the therapeutic effect. Realistic treatment using human organs is calculated in a simple and cost effective manner using the computational code, the Stopping and Range of Ions in Matter 2008 (SRIM 2008). Considering the safety of the therapy, it is suggested to give a patient orient planning of the cancer therapy. The energy losses in ionization and phonon are analyzed, which are the behaviors in the molecular level nano-scopic investigation. The different fluctuations are shown at 150 MeV, where the lowest temperature is found in proton and pancreas case. Finally, the protocol for the radiation therapy is constructed by the simulation in which the procedure for a better therapy is selected. An experimental measurement incorporated with the simulations could be programmed by this protocol.

Femtosecond laser machining for characterization of local mechanical properties of biomaterials: a case study on wood

NASA Astrophysics Data System (ADS)

Jakob, Severin; Pfeifenberger, Manuel J.; Hohenwarter, Anton; Pippan, Reinhard

2017-12-01

The standard preparation technique for micro-sized samples is focused ion beam milling, most frequently using Ga+ ions. The main drawbacks are the required processing time and the possibility and risks of ion implantation. In contrast, ultrashort pulsed laser ablation can process any type of material with ideally negligible damage to the surrounding volume and provides 4 to 6 orders of magnitude higher ablation rates than the ion beam technique. In this work, a femtosecond laser was used to prepare wood samples from spruce for mechanical testing at the micrometre level. After optimization of the different laser parameters, tensile and compressive specimens were produced from microtomed radial-tangential and longitudinal-tangential sections. Additionally, laser-processed samples were exposed to an electron beam prior to testing to study possible beam damage. The specimens originating from these different preparation conditions were mechanically tested. Advantages and limitations of the femtosecond laser preparation technique and the deformation and fracture behaviour of the samples are discussed. The results prove that femtosecond laser processing is a fast and precise preparation technique, which enables the fabrication of pristine biological samples with dimensions at the microscale.

Anisotropic vacancy-mediated phonon mode softening in Sm and Gd doped ceria.

PubMed

Jung, Dong-Hyuk; Lee, Ji-Hwan; Kilic, Mehmet Emin; Soon, Aloysius

2018-04-18

Ceria doped with Sm and Gd (SDC and GDC) has been suggested as a promising candidate for the electrolyte used in solid oxide fuel cells (SOFCs), since it has relatively high oxygen ion conductivity at intermediate temperature. There have been many previous experimental and computational studies to investigate the properties, structure, and effect of vacancies, etc. for SDC and GDC. However, in these previous studies, it is commonly assumed that the interaction between oxygen vacancies is negligible and many focus only on the mono-vacancy system. In addition, the possibility of anisotropic vibrational motion of the oxygen ions around vacancies is often neglected. In this paper, using both first-principle density-functional theory and classical molecular dynamics calculations, we investigate the structural and vibrational properties of the optimized SDC and GDC structures, such as bonding analysis, phonon density-of-state and mean-square-displacement of the oxygen ions. Also, we report the direction-dependent vibrations at the specific frequency of the oxygen ions near the vacancies, activation energies, and diffusion coefficients of SDC and GDC which can extend our understanding of diffusion dynamics in doped ceria-based electrolytes for SOFC applications.

Ion Beam And Plasma Jet Generated By A 3 kJ Plasma Focus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, L. K.; Ngoi, S. K.; Yap, S. L.

The plasma focus device is well known as a copious source of X-ray, neutrons, ion and electron beams. In this work, the characteristics of energetic ion beam emission in a 3 kJ Mather-type plasma focus is studied. The plasma focus system is operated at low pressure with argon as the working gas. The objective of the project is to obtain the argon ion beam and the plasma jet. The ion beam and plasma jet are used for material processing. In order to investigate the effect of the ion beam and plasma jet, crystalline silicon substrates are placed above the anode.more » Samples obtained after irradiation with the plasma focus discharge are analyzed by using the Scanning electron microscopy (SEM) and Energy Dispersive X-ray spectroscopy (EDX).« less

Sodium chloride toxicity and the cellular basis of salt tolerance in halophytes

PubMed Central

Flowers, Timothy J.; Munns, Rana; Colmer, Timothy D.

2015-01-01

Background Halophytes are the flora of saline soils. They adjust osmotically to soil salinity by accumulating ions and sequestering the vast majority of these (generally Na+ and Cl−) in vacuoles, while in the cytoplasm organic solutes are accumulated to prevent adverse effects on metabolism. At high salinities, however, growth is inhibited. Possible causes are: toxicity to metabolism of Na+ and/or Cl− in the cytoplasm; insufficient osmotic adjustment resulting in reduced net photosynthesis because of stomatal closure; reduced turgor for expansion growth; adverse cellular water relations if ions build up in the apoplast (cell walls) of leaves; diversion of energy needed to maintain solute homeostasis; sub-optimal levels of K+ (or other mineral nutrients) required for maintaining enzyme activities; possible damage from reactive oxygen species; or changes in hormonal concentrations. Scope This review discusses the evidence for Na+ and Cl− toxicity and the concept of tissue tolerance in relation to halophytes. Conclusions The data reviewed here suggest that halophytes tolerate cytoplasmic Na+ and Cl− concentrations of 100–200 mm, but whether these ions ever reach toxic concentrations that inhibit metabolism in the cytoplasm or cause death is unknown. Measurements of ion concentrations in the cytosol of various cell types for contrasting species and growth conditions are needed. Future work should also focus on the properties of the tonoplast that enable ion accumulation and prevent ion leakage, such as the special properties of ion transporters and of the lipids that determine membrane permeability. PMID:25466549

Atmospheric pressure ion focusing in a high-field asymmetric waveform ion mobility spectrometer

NASA Astrophysics Data System (ADS)

Guevremont, Roger; Purves, Randy W.

1999-02-01

The focusing of ions at atmospheric pressure and room temperature in a high-field asymmetric waveform ion mobility spectrometer (FAIMS) has been investigated. FAIMS operates with the application of a high-voltage, high-frequency asymmetric waveform across parallel plates. This establishes conditions wherein an ion migrates towards one of the plates because of a difference in the ion mobility at the low and high electric field conditions during application of the waveform. The migration can be stopped by applying a dc compensation voltage (CV) which serves to create a "balanced" condition wherein the ion experiences no net transverse motion. This method has also been called "transverse field compensation ion mobility spectrometry" and "field ion spectrometry®." If this experiment is conducted using a device with cylindrical geometry, rather than with flat plates, an ion focusing region can exist in the annular space between the two concentric cylinders. Ion trajectory modeling showed that the behavior of the ions in the cylindrical geometry FAIMS analyzer was unlike any previously described atmospheric pressure ion optics system. The ions appeared to be trapped, or focused by being caught between two opposing forces. Requirements for establishing this focus for a given ion were identified: the applied waveform must be asymmetric, the electric field must be sufficiently high that the mobility of the ion deviates from its low-field value during the high-voltage portion of the asymmetric waveform, and finally, the electric field must be nonuniform in space (e.g., cylindrical or spherical geometry). Experimental observations with a prototype FAIMS device, which was designed to measure the radial distribution of ions in the FAIMS analyzer region, have confirmed the results of ion trajectory modeling.

EUD-based biological optimization for carbon ion therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brüningk, Sarah C., E-mail: sarah.brueningk@icr.ac.uk; Kamp, Florian; Wilkens, Jan J.

2015-11-15

Purpose: Treatment planning for carbon ion therapy requires an accurate modeling of the biological response of each tissue to estimate the clinical outcome of a treatment. The relative biological effectiveness (RBE) accounts for this biological response on a cellular level but does not refer to the actual impact on the organ as a whole. For photon therapy, the concept of equivalent uniform dose (EUD) represents a simple model to take the organ response into account, yet so far no formulation of EUD has been reported that is suitable to carbon ion therapy. The authors introduce the concept of an equivalentmore » uniform effect (EUE) that is directly applicable to both ion and photon therapies and exemplarily implemented it as a basis for biological treatment plan optimization for carbon ion therapy. Methods: In addition to a classical EUD concept, which calculates a generalized mean over the RBE-weighted dose distribution, the authors propose the EUE to simplify the optimization process of carbon ion therapy plans. The EUE is defined as the biologically equivalent uniform effect that yields the same probability of injury as the inhomogeneous effect distribution in an organ. Its mathematical formulation is based on the generalized mean effect using an effect-volume parameter to account for different organ architectures and is thus independent of a reference radiation. For both EUD concepts, quadratic and logistic objective functions are implemented into a research treatment planning system. A flexible implementation allows choosing for each structure between biological effect constraints per voxel and EUD constraints per structure. Exemplary treatment plans are calculated for a head-and-neck patient for multiple combinations of objective functions and optimization parameters. Results: Treatment plans optimized using an EUE-based objective function were comparable to those optimized with an RBE-weighted EUD-based approach. In agreement with previous results from photon therapy, the optimization by biological objective functions resulted in slightly superior treatment plans in terms of final EUD for the organs at risk (OARs) compared to voxel-based optimization approaches. This observation was made independent of the underlying objective function metric. An absolute gain in OAR sparing was observed for quadratic objective functions, whereas intersecting DVHs were found for logistic approaches. Even for considerable under- or overestimations of the used effect- or dose–volume parameters during the optimization, treatment plans were obtained that were of similar quality as the results of a voxel-based optimization. Conclusions: EUD-based optimization with either of the presented concepts can successfully be applied to treatment plan optimization. This makes EUE-based optimization for carbon ion therapy a useful tool to optimize more specifically in the sense of biological outcome while voxel-to-voxel variations of the biological effectiveness are still properly accounted for. This may be advantageous in terms of computational cost during treatment plan optimization but also enables a straight forward comparison of different fractionation schemes or treatment modalities.« less

Ion manipulations in structures for lossless ion manipulations (SLIM): computational evaluation of a 90° turn and a switch

DOE PAGES

Garimella, Sandilya V. B.; Ibrahim, Yehia. M.; Webb, Ian K.; ...

2015-08-19

The process of redirecting ions through 90° turns and ‘tee’ switches utilizing Structures for Lossless Ion Manipulations (SLIM) was evaluated using theoretical and simulation methods at 4 Torr pressure. SIMION simulations were used to optimize and evaluate conditions for performing turns without loss of signal intensity or ion mobility resolving power. Fundamental considerations indicated that the “race track” effect during ion turns may incur only small losses to the ion mobility resolving power at 4 Torr pressure for the typical plume widths predicted in an optimized SLIM ‘tee’ switch design. The dynamic switching of ions into orthogonal channels was alsomore » evaluated using SIMION ion trajectory simulations, and achieved similar performance. Simulation results were in close agreement with experimental results and were used to refine SLIM designs and applied potentials for their use.« less

Ion collection from a plasma by a pinhole

NASA Technical Reports Server (NTRS)

Snyder, David B.; Herr, Joel L.

1992-01-01

Ion focusing by a biased pinhole is studied numerically. Laplace's equation is solved in 3-D for cylindrical symmetry on a constant grid to determine the potential field produced by a biased pinhole in a dielectric material. Focusing factors are studied for ions of uniform incident velocity with a 3-D Maxwellian distribution superimposed. Ion currents to the pinhole are found by particle tracking. The focusing factor of positive ions as a function of initial velocity, temperature, injection radius, and hole size is reported. For a typical Space Station Freedom environment (oxygen ions having a 4.5 eV ram energy, 0.1 eV temperature, and a -140 V biased pinhole), a focusing factor of 13.35 is found for a 1.5 mm radius pinhole.

Laser-pulse compression in a collisional plasma under weak-relativistic ponderomotive nonlinearity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Mamta; Gupta, D. N., E-mail: dngupta@physics.du.ac.in

We present theory and numerical analysis which demonstrate laser-pulse compression in a collisional plasma under the weak-relativistic ponderomotive nonlinearity. Plasma equilibrium density is modified due to the ohmic heating of electrons, the collisions, and the weak relativistic-ponderomotive force during the interaction of a laser pulse with plasmas. First, within one-dimensional analysis, the longitudinal self-compression mechanism is discussed. Three-dimensional analysis (spatiotemporal) of laser pulse propagation is also investigated by coupling the self-compression with the self-focusing. In the regime in which the laser becomes self-focused due to the weak relativistic-ponderomotive nonlinearity, we provide results for enhanced pulse compression. The results show thatmore » the matched interplay between self-focusing and self-compression can improve significantly the temporal profile of the compressed pulse. Enhanced pulse compression can be achieved by optimizing and selecting the parameters such as collision frequency, ion-temperature, and laser intensity.« less

4D Optimization of Scanned Ion Beam Tracking Therapy for Moving Tumors

PubMed Central

Eley, John Gordon; Newhauser, Wayne David; Lüchtenborg, Robert; Graeff, Christian; Bert, Christoph

2014-01-01

Motion mitigation strategies are needed to fully realize the theoretical advantages of scanned ion beam therapy for patients with moving tumors. The purpose of this study was to determine whether a new four-dimensional (4D) optimization approach for scanned-ion-beam tracking could reduce dose to avoidance volumes near a moving target while maintaining target dose coverage, compared to an existing 3D-optimized beam tracking approach. We tested these approaches computationally using a simple 4D geometrical phantom and a complex anatomic phantom, that is, a 4D computed tomogram of the thorax of a lung cancer patient. We also validated our findings using measurements of carbon-ion beams with a motorized film phantom. Relative to 3D-optimized beam tracking, 4D-optimized beam tracking reduced the maximum predicted dose to avoidance volumes by 53% in the simple phantom and by 13% in the thorax phantom. 4D-optimized beam tracking provided similar target dose homogeneity in the simple phantom (standard deviation of target dose was 0.4% versus 0.3%) and dramatically superior homogeneity in the thorax phantom (D5-D95 was 1.9% versus 38.7%). Measurements demonstrated that delivery of 4D-optimized beam tracking was technically feasible and confirmed a 42% decrease in maximum film exposure in the avoidance region compared with 3D-optimized beam tracking. In conclusion, we found that 4D-optimized beam tracking can reduce the maximum dose to avoidance volumes near a moving target while maintaining target dose coverage, compared with 3D-optimized beam tracking. PMID:24889215

4D optimization of scanned ion beam tracking therapy for moving tumors

NASA Astrophysics Data System (ADS)

Eley, John Gordon; Newhauser, Wayne David; Lüchtenborg, Robert; Graeff, Christian; Bert, Christoph

2014-07-01

Motion mitigation strategies are needed to fully realize the theoretical advantages of scanned ion beam therapy for patients with moving tumors. The purpose of this study was to determine whether a new four-dimensional (4D) optimization approach for scanned-ion-beam tracking could reduce dose to avoidance volumes near a moving target while maintaining target dose coverage, compared to an existing 3D-optimized beam tracking approach. We tested these approaches computationally using a simple 4D geometrical phantom and a complex anatomic phantom, that is, a 4D computed tomogram of the thorax of a lung cancer patient. We also validated our findings using measurements of carbon-ion beams with a motorized film phantom. Relative to 3D-optimized beam tracking, 4D-optimized beam tracking reduced the maximum predicted dose to avoidance volumes by 53% in the simple phantom and by 13% in the thorax phantom. 4D-optimized beam tracking provided similar target dose homogeneity in the simple phantom (standard deviation of target dose was 0.4% versus 0.3%) and dramatically superior homogeneity in the thorax phantom (D5-D95 was 1.9% versus 38.7%). Measurements demonstrated that delivery of 4D-optimized beam tracking was technically feasible and confirmed a 42% decrease in maximum film exposure in the avoidance region compared with 3D-optimized beam tracking. In conclusion, we found that 4D-optimized beam tracking can reduce the maximum dose to avoidance volumes near a moving target while maintaining target dose coverage, compared with 3D-optimized beam tracking.

Asteroid Redirection Mission Evaluation Using Multiple Landers

NASA Astrophysics Data System (ADS)

Bazzocchi, Michael C. F.; Emami, M. Reza

2018-06-01

In this paper, a low-thrust tugboat redirection method is assessed using multiple spacecraft for a target range of small near-Earth asteroids. The benefits of a landed configuration of tugboat spacecraft in formation are examined for the redirection of a near-Earth asteroid. The tugboat method uses a gimballed thruster with a highly collimated ion beam to generate a thrust on the asteroid. The target asteroid range focuses on near-Earth asteroids smaller than 150 m in diameter, and carbonaceous (C-type) asteroids, due to the volatiles available for in-situ utilization. The assessment focuses primarily on the three key parameters, i.e., the asteroid mass redirected, the timeframe for redirection, and the overall system cost. An evaluation methodology for each parameter is discussed in detail, and the parameters are employed to determine the expected return and feasibility of the redirection mission. The number of spacecraft employed is optimized along with the electrical power needed for each spacecraft to ensure the highest possible return on investment. A discussion of the optimization results and the benefits of spacecraft formation for the tugboat method are presented.

Development of the dense plasma focus for short-pulse applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bennett, N.; Blasco, M.; Breeding, K.

The dense plasma focus (DPF) has long been considered a compact source for pulsed neutrons and has traditionally been optimized for the total neutron yield. Here, we describe the efforts to optimize the DPF for short-pulse applications by introducing a reentrant cathode at the end of the coaxial plasma gun. We reduced the resulting neutron pulse widths by an average of 21±921±9% from the traditional long-drift DPF design. Pulse widths and yields achieved from deuterium-tritium fusion at 2 MA are 61.8±30.761.8±30.7 ns FWHM and 1.84±0.49×10121.84±0.49×10 12 neutrons per shot. Simulations were conducted concurrently to elucidate the DPF operation and confirmmore » the role of the reentrant cathode. Furthermore, a hybrid fluid-kinetic particle-in-cell modeling capability demonstrates correct sheath velocities, plasma instabilities, and fusion yield rates. Consistent with previous findings that the DPF is dominated by beam-target fusion from superthermal ions, we estimate that the thermonuclear contribution is at the 1% level.« less

Asteroid Redirection Mission Evaluation Using Multiple Landers

NASA Astrophysics Data System (ADS)

Bazzocchi, Michael C. F.; Emami, M. Reza

2018-01-01

In this paper, a low-thrust tugboat redirection method is assessed using multiple spacecraft for a target range of small near-Earth asteroids. The benefits of a landed configuration of tugboat spacecraft in formation are examined for the redirection of a near-Earth asteroid. The tugboat method uses a gimballed thruster with a highly collimated ion beam to generate a thrust on the asteroid. The target asteroid range focuses on near-Earth asteroids smaller than 150 m in diameter, and carbonaceous (C-type) asteroids, due to the volatiles available for in-situ utilization. The assessment focuses primarily on the three key parameters, i.e., the asteroid mass redirected, the timeframe for redirection, and the overall system cost. An evaluation methodology for each parameter is discussed in detail, and the parameters are employed to determine the expected return and feasibility of the redirection mission. The number of spacecraft employed is optimized along with the electrical power needed for each spacecraft to ensure the highest possible return on investment. A discussion of the optimization results and the benefits of spacecraft formation for the tugboat method are presented.

Development of the dense plasma focus for short-pulse applications

DOE PAGES

Bennett, N.; Blasco, M.; Breeding, K.; ...

2017-01-05

The dense plasma focus (DPF) has long been considered a compact source for pulsed neutrons and has traditionally been optimized for the total neutron yield. Here, we describe the efforts to optimize the DPF for short-pulse applications by introducing a reentrant cathode at the end of the coaxial plasma gun. We reduced the resulting neutron pulse widths by an average of 21±921±9% from the traditional long-drift DPF design. Pulse widths and yields achieved from deuterium-tritium fusion at 2 MA are 61.8±30.761.8±30.7 ns FWHM and 1.84±0.49×10121.84±0.49×10 12 neutrons per shot. Simulations were conducted concurrently to elucidate the DPF operation and confirmmore » the role of the reentrant cathode. Furthermore, a hybrid fluid-kinetic particle-in-cell modeling capability demonstrates correct sheath velocities, plasma instabilities, and fusion yield rates. Consistent with previous findings that the DPF is dominated by beam-target fusion from superthermal ions, we estimate that the thermonuclear contribution is at the 1% level.« less

EDITORIAL: Focus on Heavy Ions in Biophysics and Medical Physics FOCUS ON HEAVY IONS IN BIOPHYSICS AND MEDICAL PHYSICS

NASA Astrophysics Data System (ADS)

Durante, Marco

2008-07-01

Interest in energetic heavy ions is rapidly increasing in the field of biomedicine. Heavy ions are normally excluded from radiation protection, because they are not normally experienced by humans on Earth. However, knowledge of heavy ion biophysics is necessary in two fields: charged particle cancer therapy (hadrontherapy), and radiation protection in space missions. The possibility to cure tumours using accelerated heavy charged particles was first tested in Berkeley in the sixties, but results were not satisfactory. However, about 15 years ago therapy with carbon ions was resumed first in Japan and then in Europe. Heavy ions are preferable to photons for both physical and biological characteristics: the Bragg peak and limited lateral diffusion ensure a conformal dose distribution, while the high relative biological effectiveness and low oxygen enhancement ration in the Bragg peak region make the beam very effective in treating radioresistant and hypoxic tumours. Recent results coming from the National Institute of Radiological Sciences in Chiba (see the paper by Dr Tsujii and co-workers in this issue) and GSI (Germany) provide strong clinical evidence that heavy ions are indeed an extremely effective weapon in the fight against cancer. However, more research is needed in the field, especially on optimization of the treatment planning and risk of late effects in normal tissue, including secondary cancers. On the other hand, high-energy heavy ions are present in galactic cosmic radiation and, although they are rare as compared to protons, they give a major contribution in terms of equivalent dose to the crews of manned space exploratory-class missions. Exploration of the Solar System is now the main goal of the space program, and the risk caused by exposure to galactic cosmic radiation is considered a serious hindrance toward this goal, because of the high uncertainty on late effects of energetic heavy nuclei, and the lack of effective countermeasures. Risks include carcinogenesis, late degenerative tissue effects (including damage to the central nervous system), and hereditary effects. For these studies, microbeams represent an essential tool, considering that in space each cell in the human body will not experience more than one heavy-ion traversal. Both NASA and ESA are investing important resources in ground-based space radiation research programs, to reduce risk uncertainty and to develop countermeasures. For both cancer therapy and space radiation protection a better understanding of the effects of energetic heavy ions is needed. Physics should be improved, especially the measurements of nuclear fragmentation cross-sections, and the transport calculations. Biological effects need to be studied in greater detail, and clearly only understanding the mechanisms of heavy-ion induced biological damage will reduce the uncertainty on late effects in humans. This focus issue of New Journal of Physics aims to provide the state-of-the-art of the biophysics of energetic heavy ions and to highlight the areas where more research is urgently needed for therapy and the space program. Focus on Heavy Ions in Biophysics and Medical Physics Contents Heavy ion microprobes: a unique tool for bystander research and other radiobiological applications K O Voss, C Fournier and G Taucher-Scholz Heavy ions light flashes and brain functions: recent observations at accelerators and in spaceflight L Narici Clinical advantages of carbon-ion radiotherapy Hirohiko Tsujii, Tadashi Kamada, Masayuki Baba, Hiroshi Tsuji, Hirotoshi Kato, Shingo Kato, Shigeru Yamada, Shigeo Yasuda, Takeshi Yanagi, Hiroyuki Kato, Ryusuke Hara, Naotaka Yamamoto and Junetsu Mizoe Heavy-ion effects: from track structure to DNA and chromosome damage F Ballarini, D Alloni, A Facoetti and A Ottolenghi Shielding experiments with high-energy heavy ions for spaceflight applications C Zeitlin, S Guetersloh, L Heilbronn, J Miller, N Elkhayari, A Empl, M LeBourgeois, B W Mayes, L Pinsky, M Christl and E Kuznetsov Heavy charged particles in radiation biology and biophysics H Nikjoo, S Uehara, D Emfietzoglou and A Brahme Impact of track structure calculations on biological treatment planning in ion radiotherapy Thilo Elsässer, Richard Cunrath, Michael Krämer and Michael Scholz The physical basis for the biological action of heavy ions Jürgen Kiefer Secondary beam fragments produced by 200 MeV u-1 12C ions in water and their dose contributions in carbon ion radiotherapy K Gunzert-Marx, H Iwase, D Schardt and R S Simon

Negative ion source with low temperature transverse divergence optical system

DOEpatents

Whealton, John H.; Stirling, William L.

1986-01-01

A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

Negative ion source with low temperature transverse divergence optical system

DOEpatents

Whealton, J.H.; Stirling, W.L.

1985-03-04

A negative ion source is provided which has extremely low transverse divergence as a result of a unique ion focusing system in which the focal line of an ion beam emanating from an elongated, concave converter surface is outside of the ion exit slit of the source and the path of the exiting ions. The beam source operates with a minimum ion temperature which makes possible a sharply focused (extremely low transverse divergence) ribbon like negative ion beam.

Focused ion beam source method and apparatus

DOEpatents

Pellin, Michael J.; Lykke, Keith R.; Lill, Thorsten B.

2000-01-01

A focused ion beam having a cross section of submicron diameter, a high ion current, and a narrow energy range is generated from a target comprised of particle source material by laser ablation. The method involves directing a laser beam having a cross section of critical diameter onto the target, producing a cloud of laser ablated particles having unique characteristics, and extracting and focusing a charged particle beam from the laser ablated cloud. The method is especially suited for producing focused ion beams for semiconductor device analysis and modification.

Battery management systems (BMS) optimization for electric vehicles (EVs) in Malaysia

NASA Astrophysics Data System (ADS)

Salehen, P. M. W.; Su'ait, M. S.; Razali, H.; Sopian, K.

2017-04-01

Following the UN Climate Change Conference 2009 in Copenhagen, Denmark, Malaysia seriously committed on "Go Green" campaign with the aim to reduce 40% GHG emission by the year 2020. Therefore, the National Green Technology Policy has been legalised in 2009 with transportation as one of its focused sectors, which include hybrid (HEVs), electric vehicles (EVs) and fuel cell vehicles with the purpose of to keep up with the worst scenario. While the number of registered cars has been increasing by 1 million yearly, the amount has doubled in the last two decades. Consequently, CO2 emission in Malaysia reaches up to 97.1% and will continue to increase mainly due to the activities in the transportation sector. Nevertheless, Malaysia is now moving towards on green car which battery-based EVs. This type of transportation mainly needs power performance optimization, which is controlled by the Batteries Management System (BMS). BMS is an essential module which leads to reliable power management, optimal power performance and safe vehicle that lead back for power optimization in EVs. Thus, this paper proposes power performance optimization for various setups of lithium-ion cathode with graphene anode using MATLAB/SIMULINK software for better management performance and extended EVs driving range.

Effect of pulsed electric fields (PEF) on accumulation of selenium and zinc ions in Saccharomyces cerevisiae cells.

PubMed

Pankiewicz, Urszula; Sujka, Monika; Kowalski, Radosław; Mazurek, Artur; Włodarczyk-Stasiak, Marzena; Jamroz, Jerzy

2017-04-15

The cultures of Saccharomyces cerevisiae were treated with pulsed electric fields (PEF) in order to obtain a maximum accumulation of selenium and zinc ions (simultaneously) in the biomass. The following concentrations: 100μgSe/ml and 150μgZn/ml medium were assumed to be optimal for the maximum accumulation of these ions, that is 43.07mg/gd.m. for selenium and 14.48mg/gd.m. for zinc, in the cultures treated with PEF. At optimal PEF parameters: electric field strength of 3kV/cm and pulse width of 10μs after the treatment of 20-h culture for 10min, the maximum accumulation of both ions in the yeast cells was observed. Application of PEF caused the increase of ions accumulation by 65% for selenium and 100% for zinc. Optimization of PEF parameters led to the further rise in the both ions accumulation resulting in over 2-fold and 2.5-fold higher concentration of selenium and zinc. Copyright © 2016 Elsevier Ltd. All rights reserved.

A high brightness source for nano-probe secondary ion mass spectrometry

NASA Astrophysics Data System (ADS)

Smith, N. S.; Tesch, P. P.; Martin, N. P.; Kinion, D. E.

2008-12-01

The two most prevalent ion source technologies in the field of surface analysis and surface machining are the Duoplasmatron and the liquid metal ion source (LMIS). There have been many efforts in this area of research to develop an alternative source [ S.K. Guharay, J. Orloff, M. Wada, IEEE Trans. Plasma Sci. 33 (6) (2005) 1911; N.S. Smith, W.P. Skoczylas, S.M. Kellogg, D.E. Kinion, P.P. Tesch, O. Sutherland, A. Aanesland, R.W. Boswell, J. Vac. Sci. Technol. B 24 (6) (2006) 2902-2906] with the brightness of a LMIS and yet the ability to produce secondary ion yield enhancing species such as oxygen. However, to date a viable alternative has not been realized. The high brightness and small virtual source size of the LMIS are advantageous for forming high resolution probes but a significant disadvantage when beam currents in excess of 100 nA are required, due to the effects of spherical aberration from the optical column. At these higher currents a source with a high angular intensity is optimal and in fact the relatively moderate brightness of today's plasma ion sources prevail in this operating regime. Both the LMIS and Duoplasmatron suffer from a large axial energy spread resulting in further limitations when forming focused beams at the chromatic limit where the figure-of-merit is inversely proportional to the square of the energy spread. Also, both of these ion sources operate with a very limited range of ion species. This article reviews some of the latest developments and some future potential in this area of instrument development. Here we present an approach to source development that could lead to oxygen ion beam SIMS imaging with 10 nm resolution, using a 'broad area' RF gas phase ion source.

Helicon plasma generator-assisted surface conversion ion source for the production of H- ion beams at the Los Alamos Neutron Science Centera)

NASA Astrophysics Data System (ADS)

Tarvainen, O.; Rouleau, G.; Keller, R.; Geros, E.; Stelzer, J.; Ferris, J.

2008-02-01

The converter-type negative ion source currently employed at the Los Alamos Neutron Science Center (LANSCE) is based on cesium enhanced surface production of H- ion beams in a filament-driven discharge. In this kind of an ion source the extracted H- beam current is limited by the achievable plasma density which depends primarily on the electron emission current from the filaments. The emission current can be increased by increasing the filament temperature but, unfortunately, this leads not only to shorter filament lifetime but also to an increase in metal evaporation from the filament, which deposits on the H- converter surface and degrades its performance. Therefore, we have started an ion source development project focused on replacing these thermionic cathodes (filaments) of the converter source by a helicon plasma generator capable of producing high-density hydrogen plasmas with low electron energy. In our studies which have so far shown that the plasma density of the surface conversion source can be increased significantly by exciting a helicon wave in the plasma, and we expect to improve the performance of the surface converter H- ion source in terms of beam brightness and time between services. The design of this new source and preliminary results are presented, along with a discussion of physical processes relevant for H- ion beam production with this novel design. Ultimately, we perceive this approach as an interim step towards our long-term goal, combining a helicon plasma generator with an SNS-type main discharge chamber, which will allow us to individually optimize the plasma properties of the plasma cathode (helicon) and H- production (main discharge) in order to further improve the brightness of extracted H- ion beams.

Helicon plasma generator-assisted surface conversion ion source for the production of H(-) ion beams at the Los Alamos Neutron Science Center.

PubMed

Tarvainen, O; Rouleau, G; Keller, R; Geros, E; Stelzer, J; Ferris, J

2008-02-01

The converter-type negative ion source currently employed at the Los Alamos Neutron Science Center (LANSCE) is based on cesium enhanced surface production of H(-) ion beams in a filament-driven discharge. In this kind of an ion source the extracted H(-) beam current is limited by the achievable plasma density which depends primarily on the electron emission current from the filaments. The emission current can be increased by increasing the filament temperature but, unfortunately, this leads not only to shorter filament lifetime but also to an increase in metal evaporation from the filament, which deposits on the H(-) converter surface and degrades its performance. Therefore, we have started an ion source development project focused on replacing these thermionic cathodes (filaments) of the converter source by a helicon plasma generator capable of producing high-density hydrogen plasmas with low electron energy. In our studies which have so far shown that the plasma density of the surface conversion source can be increased significantly by exciting a helicon wave in the plasma, and we expect to improve the performance of the surface converter H(-) ion source in terms of beam brightness and time between services. The design of this new source and preliminary results are presented, along with a discussion of physical processes relevant for H(-) ion beam production with this novel design. Ultimately, we perceive this approach as an interim step towards our long-term goal, combining a helicon plasma generator with an SNS-type main discharge chamber, which will allow us to individually optimize the plasma properties of the plasma cathode (helicon) and H(-) production (main discharge) in order to further improve the brightness of extracted H(-) ion beams.

Bulk ion heating with ICRF waves in tokamaks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mantsinen, M. J., E-mail: mervi.mantsinen@bsc.es; Barcelona Supercomputing Center, Barcelona; Bilato, R.

2015-12-10

Heating with ICRF waves is a well-established method on present-day tokamaks and one of the heating systems foreseen for ITER. However, further work is still needed to test and optimize its performance in fusion devices with metallic high-Z plasma facing components (PFCs) in preparation of ITER and DEMO operation. This is of particular importance for the bulk ion heating capabilities of ICRF waves. Efficient bulk ion heating with the standard ITER ICRF scheme, i.e. the second harmonic heating of tritium with or without {sup 3}He minority, was demonstrated in experiments carried out in deuterium-tritium plasmas on JET and TFTR andmore » is confirmed by ICRF modelling. This paper focuses on recent experiments with {sup 3}He minority heating for bulk ion heating on the ASDEX Upgrade (AUG) tokamak with ITER-relevant all-tungsten PFCs. An increase of 80% in the central ion temperature T{sub i} from 3 to 5.5 keV was achieved when 3 MW of ICRF power tuned to the central {sup 3}He ion cyclotron resonance was added to 4.5 MW of deuterium NBI. The radial gradient of the T{sub i} profile reached locally values up to about 50 keV/m and the normalized logarithmic ion temperature gradients R/LT{sub i} of about 20, which are unusually large for AUG plasmas. The large changes in the T{sub i} profiles were accompanied by significant changes in measured plasma toroidal rotation, plasma impurity profiles and MHD activity, which indicate concomitant changes in plasma properties with the application of ICRF waves. When the {sup 3}He concentration was increased above the optimum range for bulk ion heating, a weaker peaking of the ion temperature profile was observed, in line with theoretical expectations.« less

Mercury ion thruster technology

NASA Technical Reports Server (NTRS)

Beattie, J. R.; Matossian, J. N.

1989-01-01

The Mercury Ion Thruster Technology program was an investigation for improving the understanding of state-of-the-art mercury ion thrusters. Emphasis was placed on optimizing the performance and simplifying the design of the 30 cm diameter ring-cusp discharge chamber. Thruster performance was improved considerably; the baseline beam-ion production cost of the optimized configuration was reduced to Epsilon (sub i) perspective to 130 eV/ion. At a discharge propellant-utilization efficiency of 95 percent, the beam-ion production cost was reduced to about 155 eV/ion, representing a reduction of about 40 eV/ion over the corresponding value for the 30 cm diameter J-series thruster. Comprehensive Langmuir-probe surveys were obtained and compared with similar measurements for a J-series thruster. A successful volume-averaging scheme was developed to correlate thruster performance with the dominant plasma processes that prevail in the two thruster designs. The average Maxwellian electron temperature in the optimized ring-cusp design is as much as 1 eV higher than it is in the J-series thruster. Advances in ion-extraction electrode fabrication technology were made by improving materials selection criteria, hydroforming and stress-relieving tooling, and fabrications procedures. An ion-extraction performance study was conducted to assess the effect of screen aperture size on ion-optics performance and to verify the effectiveness of a beam-vectoring model for three-grid ion optics. An assessment of the technology readiness of the J-series thruster was completed, and operation of an 8 cm IAPS thruster using a simplified power processor was demonstrated.

Development of Diagnostics for the Livermore DPF Devices

NASA Astrophysics Data System (ADS)

Mitrani, James; Prasad, Rahul R.; Podpaly, Yuri A.; Cooper, Christopher M.; Chapman, Steven F.; Shaw, Brian H.; Povilus, Alexander P.; Schmidt, Andrea

2017-10-01

LLNL is commissioning several new diagnostics to understand and optimize ion and neutron production in their dense plasma focus (DPF) systems. Gas fills used in DPF devices at LLNL are Deuterium (D2) and He accelerated onto a Be target, for production of neutrons. Neutron yields are currently measured with Helium-3 tubes, and development of yttrium-based activation detectors is currently underway. Neutron time-of-flight (nTOF) signals from prompt neutrons will be measured with gadolinium-doped liquid scintillators. An ion energy analyzer will be used to diagnose energy distribution of D + and He +2 ions. Additionally, a fast frame ICCD camera has been applied to image the plasma sheath during the rundown and pinch phases. Sheath velocity will be measured with an array of discrete photodiodes with ns time responses. A discussion of our results will be presented. Prepared by LLNL under Contract DE-AC52-07NA27344, and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL and the Office of Defense Nuclear Nonproliferation Research and Development within U.S. Department of Energy.

Geant4 hadronic physics for space radiation environment.

PubMed

Ivantchenko, Anton V; Ivanchenko, Vladimir N; Molina, Jose-Manuel Quesada; Incerti, Sebastien L

2012-01-01

To test and to develop Geant4 (Geometry And Tracking version 4) Monte Carlo hadronic models with focus on applications in a space radiation environment. The Monte Carlo simulations have been performed using the Geant4 toolkit. Binary (BIC), its extension for incident light ions (BIC-ion) and Bertini (BERT) cascades were used as main Monte Carlo generators. For comparisons purposes, some other models were tested too. The hadronic testing suite has been used as a primary tool for model development and validation against experimental data. The Geant4 pre-compound (PRECO) and de-excitation (DEE) models were revised and improved. Proton, neutron, pion, and ion nuclear interactions were simulated with the recent version of Geant4 9.4 and were compared with experimental data from thin and thick target experiments. The Geant4 toolkit offers a large set of models allowing effective simulation of interactions of particles with matter. We have tested different Monte Carlo generators with our hadronic testing suite and accordingly we can propose an optimal configuration of Geant4 models for the simulation of the space radiation environment.

Urea-based hydrothermal synthesis of LiNi0.5Co0.2Mn0.3O2 cathode material for Li-ion battery

NASA Astrophysics Data System (ADS)

Shi, Yang; Zhang, Minghao; Fang, Chengcheng; Meng, Ying Shirley

2018-08-01

A urea-based hydrothermal approach has been applied to synthesize LiNi0.5Co0.2Mn0.3O2 (NCM523) cathode materials with focus on investigating the influence of the reaction conditions on their electrochemical performance. The compositions of the carbonate precursor are precisely controlled by tuning urea concentration, hydrothermal reaction temperature, and time. The mole ratio between urea and transition metal ions and reaction temperature influence the composition of the precursor; while the reaction time influences the electrochemical performance of the final product. The optimized materials show better cyclability and rate capability compared with the materials synthesized with other hydrothermal reaction conditions. The enhancement is attributed to the larger Li+ diffusion coefficient and lower charge transfer resistance, which are due to the lower degree of Li/Ni cation mixing and more uniform distribution of transition metal ions. This work is a systematic study on the synthesis of NCM523 cathode material by a urea-based hydrothermal approach.

Imaging crystal spectrometer for high-resolution x-ray measurements on electron beam ion traps and tokamaks

DOE PAGES

Beiersdorfer, P.; Magee, E. W.; Hell, N.; ...

2016-09-09

Here, we describe a crystal spectrometer implemented on the Livermore electron beam ion traps that employ two spherically bent quartz crystals and a cryogenically cooled back-illuminated charge-coupled device detector to measure x rays with a nominal resolving power of λ/Δλ ≥ 10 000. Its focusing properties allow us to record x rays either with the plane of dispersion perpendicular or parallel to the electron beam and, thus, to preferentially select one of the two linear x-ray polarization components. Moreover, by choice of dispersion plane and focussing conditions, we use the instrument either to image the distribution of the ions withinmore » the 2 cm long trap region, or to concentrate x rays of a given energy to a point on the detector, which optimizes the signal-to-noise ratio. We demonstrate the operation and utility of the new instrument by presenting spectra of Mo 34+, which prepares the instrument for use as a core impurity diagnostic on the NSTX-U spherical torus and other magnetic fusion devices that employ molybdenum as plasma facing components.« less

Focused electron and ion beam systems

DOEpatents

Leung, Ka-Ngo; Reijonen, Jani; Persaud, Arun; Ji, Qing; Jiang, Ximan

2004-07-27

An electron beam system is based on a plasma generator in a plasma ion source with an accelerator column. The electrons are extracted from a plasma cathode in a plasma ion source, e.g. a multicusp plasma ion source. The beam can be scanned in both the x and y directions, and the system can be operated with multiple beamlets. A compact focused ion or electron beam system has a plasma ion source and an all-electrostatic beam acceleration and focusing column. The ion source is a small chamber with the plasma produced by radio-frequency (RF) induction discharge. The RF antenna is wound outside the chamber and connected to an RF supply. Ions or electrons can be extracted from the source. A multi-beam system has several sources of different species and an electron beam source.

Dynamic transfer applied to secondary ion imaging over large scanned fields with the nanoSIMS 50 at high mass resolution

NASA Astrophysics Data System (ADS)

Slodzian, Georges; Wu, Ting-Di; Duprat, Jean; Engrand, Cécile; Guerquin-Kern, Jean-Luc

2017-12-01

Dynamic transfer is an adaptive optical approach used for coupling a scanning ion probe with the mass spectrometer designed for analyzing sputtered ions emanating from the probe impact. Its tuning is of crucial importance for getting uniform signal collection over large scanning fields and therefore scanning images free of vignetting in a context of high mass resolution. Revisiting the optical design of the NanoSIMS 50 instrument, where the same set of lenses focuses the primary ion probe on the sample and collects secondary ions from the sample, led us to develop novel experimental procedures to achieve dynamic transfer tuning and overcome instrumental imperfections. It is the case for scanning distortion that may be induced by the octopole used for correcting probe astigmatism and may cause irreducible vignetting on scanning images. We show that it is possible to develop complete tuning procedures by compromising temporarily on the sharpness of the probe focus. Most importantly, we show that, in a context of high mass resolution, the transfer does not significantly disturb isotopic ratios over large scanned fields provided external coils are properly adjusted to compensate ambient magnetic fields. Deepening the procedures led us to demonstrate that the scanning center of the probe may not coincide with the imaging center of COOL, Coaxial Objective Lenses forming the probe and extracting secondary ions. We have checked that bringing those two centers into coincidence resulted in a better image quality over large fields. In the present work, we show how to handle the secondary beam in order to position it before it enters the spectrometer. That capability is essential for optimizing transmission at high mass resolution by aligning the secondary beam axis on a given entrance axis of the spectrometer. These results led us to propose several instrumental improvements including the crucial interest of an additional octopole upstream in the primary ion probe column to prevent scanning distortion when performing astigmatism correction and the possibility of offsetting primary beam deviating plates to bring scanning and imaging centers in coincidence.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogacz, Alex

Baseline design of the JLEIC booster synchrotron is presented. Its aim is to inject and accumulate heavy ions and protons at 285 MeV, to accelerate them to about 7 GeV, and finally to extract the beam into the ion collider ring. The Figure-8 ring features two 2600 achromatic arcs configured with negative momentum compaction optics, designed to avoid transition crossing for all ion species during the course of acceleration. The lattice also features a specialized high dispersion injection insert optimized to facilitate the transverse phase-space painting in both planes for multi-turn ion injection. Furthermore, the lattice has been optimized tomore » ease chromaticity correction with two families of sextupoles in each plane. The booster ring is configured with super-ferric, 3 Tesla bends. We are presently launching optimization of the booster synchrotron design to operate in the extreme space-charge dominated regime.« less

Classification of heavy metal ions present in multi-frequency multi-electrode potable water data using evolutionary algorithm

NASA Astrophysics Data System (ADS)

Karkra, Rashmi; Kumar, Prashant; Bansod, Baban K. S.; Bagchi, Sudeshna; Sharma, Pooja; Krishna, C. Rama

2017-11-01

Access to potable water for the common people is one of the most challenging tasks in the present era. Contamination of drinking water has become a serious problem due to various anthropogenic and geogenic events. The paper demonstrates the application of evolutionary algorithms, viz., particle swan optimization and genetic algorithm to 24 water samples containing eight different heavy metal ions (Cd, Cu, Co, Pb, Zn, Ar, Cr and Ni) for the optimal estimation of electrode and frequency to classify the heavy metal ions. The work has been carried out on multi-variate data, viz., single electrode multi-frequency, single frequency multi-electrode and multi-frequency multi-electrode water samples. The electrodes used are platinum, gold, silver nanoparticles and glassy carbon electrodes. Various hazardous metal ions present in the water samples have been optimally classified and validated by the application of Davis Bouldin index. Such studies are useful in the segregation of hazardous heavy metal ions found in water resources, thereby quantifying the degree of water quality.

Preservation of protein fluorescence in embedded human dendritic cells for targeted 3D light and electron microscopy.

PubMed

Höhn, K; Fuchs, J; Fröber, A; Kirmse, R; Glass, B; Anders-Össwein, M; Walther, P; Kräusslich, H-G; Dietrich, C

2015-08-01

In this study, we present a correlative microscopy workflow to combine detailed 3D fluorescence light microscopy data with ultrastructural information gained by 3D focused ion beam assisted scanning electron microscopy. The workflow is based on an optimized high pressure freezing/freeze substitution protocol that preserves good ultrastructural detail along with retaining the fluorescence signal in the resin embedded specimens. Consequently, cellular structures of interest can readily be identified and imaged by state of the art 3D confocal fluorescence microscopy and are precisely referenced with respect to an imprinted coordinate system on the surface of the resin block. This allows precise guidance of the focused ion beam assisted scanning electron microscopy and limits the volume to be imaged to the structure of interest. This, in turn, minimizes the total acquisition time necessary to conduct the time consuming ultrastructural scanning electron microscope imaging while eliminating the risk to miss parts of the target structure. We illustrate the value of this workflow for targeting virus compartments, which are formed in HIV-pulsed mature human dendritic cells. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

The interplay of nanointerface curvature and calcium binding in weak polyelectrolyte-coated nanoparticles.

PubMed

Nap, Rikkert J; Gonzalez Solveyra, Estefania; Szleifer, Igal

2018-05-01

When engineering nanomaterials for application in biological systems, it is important to understand how multivalent ions, such as calcium, affect the structural and chemical properties of polymer-modified nanoconstructs. In this work, a recently developed molecular theory was employed to study the effect of surface curvature on the calcium-induced collapse of end-tethered weak polyelectrolytes. In particular, we focused on cylindrical and spherical nanoparticles coated with poly(acrylic acid) in the presence of different amounts of Ca2+ ions. We describe the structural changes that grafted polyelectrolytes undergo as a function of calcium concentration, surface curvature, and morphology. The polymer layers collapse in aqueous solutions that contain sufficient amounts of Ca2+ ions. This collapse, due to the formation of calcium bridges, is not only controlled by the calcium ion concentration but also strongly influenced by the curvature of the tethering surface. The transition from a swollen to a collapsed layer as a function of calcium concentration broadens and shifts to lower amounts of calcium ions as a function of the radius of cylindrical and spherical nanoparticles. The results show how the interplay between calcium binding and surface curvature governs the structural and functional properties of the polymer molecules. This would directly impact the fate of weak polyelectrolyte-coated nanoparticles in biological environments, in which calcium levels are tightly regulated. Understanding such interplay would also contribute to the rational design and optimization of smart interfaces with applications in, e.g., salt-sensitive and ion-responsive materials and devices.

First-Principles Investigation of Electronic Properties in Sodium-Ion Electrolytes for Solid-State Battery Materials

NASA Astrophysics Data System (ADS)

Rush, Larry E., Jr.

This thesis mainly focuses on characterizing and understanding the electronic properties of sodium-ion electrolytes using first-principles calculations. The core of these calculations is built upon a functional understanding of the relationship between quantum mechanics and the crystalline geometries that contribute to unique properties of materials such as diffusion mechanisms of ions within solid-state materials, conductivity, and ground state structures. The goal of this body of work is to understand how this relationship can give us insight into materials that might have use in an emerging field within battery technology. Sodium-ion solid-state batteries are an auspicious technology because nature has provided us with widely distributed precursor materials in such a way that removes geopolitical constraints in its construction and distribution. This is extremely important to individuals (and a collection of individuals) who want to expedite the wide use of clean and renewable energy from a societal perspective. An example is Morocco's initiative to generate 52% of its total energy consumption from clean and renewable energy sources to eliminate dependencies on foreign countries to supply energy resources. Sodium-ion solid-state batteries are an inexpensive option for large-scale grid storage, so this could play a role in providing a cost-effective option for Morocco. The challenging part is to sift through the large chemical space of sodium-ion solid-state electrolytes to find optimal materials for battery technology, and that is what motivates this body of work.

Focusing Intense Charged Particle Beams with Achromatic Effects for Heavy Ion Fusion

NASA Astrophysics Data System (ADS)

Mitrani, James; Kaganovich, Igor

2012-10-01

Final focusing systems designed to minimize the effects of chromatic aberrations in the Neutralized Drift Compression Experiment (NDCX-II) are described. NDCX-II is a linear induction accelerator, designed to accelerate short bunches at high current. Previous experiments showed that neutralized drift compression significantly compresses the beam longitudinally (˜60x) in the z-direction, resulting in a narrow distribution in z-space, but a wide distribution in pz-space. Using simple lenses (e.g., solenoids, quadrupoles) to focus beam bunches with wide distributions in pz-space results in chromatic aberrations, leading to lower beam intensities (J/cm^2). Therefore, the final focusing system must be designed to compensate for chromatic aberrations. The paraxial ray equations and beam envelope equations are numerically solved for parameters appropriate to NDCX-II. Based on these results, conceptual designs for final focusing systems using a combination of solenoids and/or quadrupoles are optimized to compensate for chromatic aberrations. Lens aberrations and emittance growth will be investigated, and analytical results will be compared with results from numerical particle-in-cell (PIC) simulation codes.

First Absolutely Calibrated Localized Measurements of Ion Velocity in the MST in Locked and Rotating Plasmas

NASA Astrophysics Data System (ADS)

Baltzer, M.; Craig, D.; den Hartog, D. J.; Nornberg, M. D.; Munaretto, S.

2015-11-01

An Ion Doppler Spectrometer (IDS) is used on MST for high time-resolution passive and active measurements of impurity ion emission. Absolutely calibrated measurements of flow are difficult because the spectrometer records data within 0.3 nm of the C+5 line of interest, and commercial calibration lamps do not produce lines in this narrow range . A novel optical system was designed to absolutely calibrate the IDS. The device uses an UV LED to produce a broad emission curve in the desired region. A Fabry-Perot etalon filters this light, cutting transmittance peaks into the pattern of the LED emission. An optical train of fused silica lenses focuses the light into the IDS with f/4. A holographic diffuser blurs the light cone to increase homogeneity. Using this light source, the absolute Doppler shift of ion emissions can be measured in MST plasmas. In combination with charge exchange recombination spectroscopy, localized ion velocities can now be measured. Previously, a time-averaged measurement along the chord bisecting the poloidal plane was used to calibrate the IDS; the quality of these central chord calibrations can be characterized with our absolute calibration. Calibration errors may also be quantified and minimized by optimizing the curve-fitting process. Preliminary measurements of toroidal velocity in locked and rotating plasmas will be shown. This work has been supported by the US DOE.

Optimal production of 7,10-dihydroxy-8(E)-hexadecenoic acid from palmitoleic acid by Pseudomonas aeruginosa PR3.

PubMed

Bae, Jae-Han; Suh, Min-Jung; Kim, Beom-Soo; Hou, Ching T; Lee, In-Jung; Kim, In-Hwan; Kim, Hak-Ryul

2010-09-30

The hydroxylation of unsaturated fatty acids by bacterial strains is one type of value-adding bioconversion processes. This process generates new hydroxy fatty acids (HFA) carrying special properties such as higher viscosity and reactivity compared with normal fatty acids. Among microbial strains tested for HFA production, Pseudomonas aeruginosa PR3 is well known to utilize various unsaturated fatty acids to produce mono-, di- and tri-hydroxy fatty acids. Previously we reported that strain PR3 could produce a novel value-added hydroxy fatty acid 7,10-dihydroxy-8(E)-hexadecenoic acid (DHD) from palmitoleic acid (Bae et al. (2007) Appl. Microbiol. Biotechnol. 75, 435-440). In this study, we focused on the development of the optimal nutritional and environmental conditions for DHD production from palmitoleic acid by PR3. Optimal carbon and nitrogen sources for DHD production were fructose and yeast extract, respectively. Optimal initial medium pH and incubation temperature were pH 8.0 and 30 degrees C and magnesium ion was essentially required for DHD production. Substrate concentration and time of substrate addition were also optimized. Under optimized conditions, maximal DHD production was 1600mg/l representing 26.7% conversion yield. Copyright 2009 Elsevier B.V. All rights reserved.

Optimal input shaping for Fisher identifiability of control-oriented lithium-ion battery models

NASA Astrophysics Data System (ADS)

Rothenberger, Michael J.

This dissertation examines the fundamental challenge of optimally shaping input trajectories to maximize parameter identifiability of control-oriented lithium-ion battery models. Identifiability is a property from information theory that determines the solvability of parameter estimation for mathematical models using input-output measurements. This dissertation creates a framework that exploits the Fisher information metric to quantify the level of battery parameter identifiability, optimizes this metric through input shaping, and facilitates faster and more accurate estimation. The popularity of lithium-ion batteries is growing significantly in the energy storage domain, especially for stationary and transportation applications. While these cells have excellent power and energy densities, they are plagued with safety and lifespan concerns. These concerns are often resolved in the industry through conservative current and voltage operating limits, which reduce the overall performance and still lack robustness in detecting catastrophic failure modes. New advances in automotive battery management systems mitigate these challenges through the incorporation of model-based control to increase performance, safety, and lifespan. To achieve these goals, model-based control requires accurate parameterization of the battery model. While many groups in the literature study a variety of methods to perform battery parameter estimation, a fundamental issue of poor parameter identifiability remains apparent for lithium-ion battery models. This fundamental challenge of battery identifiability is studied extensively in the literature, and some groups are even approaching the problem of improving the ability to estimate the model parameters. The first approach is to add additional sensors to the battery to gain more information that is used for estimation. The other main approach is to shape the input trajectories to increase the amount of information that can be gained from input-output measurements, and is the approach used in this dissertation. Research in the literature studies optimal current input shaping for high-order electrochemical battery models and focuses on offline laboratory cycling. While this body of research highlights improvements in identifiability through optimal input shaping, each optimal input is a function of nominal parameters, which creates a tautology. The parameter values must be known a priori to determine the optimal input for maximizing estimation speed and accuracy. The system identification literature presents multiple studies containing methods that avoid the challenges of this tautology, but these methods are absent from the battery parameter estimation domain. The gaps in the above literature are addressed in this dissertation through the following five novel and unique contributions. First, this dissertation optimizes the parameter identifiability of a thermal battery model, which Sergio Mendoza experimentally validates through a close collaboration with this dissertation's author. Second, this dissertation extends input-shaping optimization to a linear and nonlinear equivalent-circuit battery model and illustrates the substantial improvements in Fisher identifiability for a periodic optimal signal when compared against automotive benchmark cycles. Third, this dissertation presents an experimental validation study of the simulation work in the previous contribution. The estimation study shows that the automotive benchmark cycles either converge slower than the optimized cycle, or not at all for certain parameters. Fourth, this dissertation examines how automotive battery packs with additional power electronic components that dynamically route current to individual cells/modules can be used for parameter identifiability optimization. While the user and vehicle supervisory controller dictate the current demand for these packs, the optimized internal allocation of current still improves identifiability. Finally, this dissertation presents a robust Bayesian sequential input shaping optimization study to maximize the conditional Fisher information of the battery model parameters without prior knowledge of the nominal parameter set. This iterative algorithm only requires knowledge of the prior parameter distributions to converge to the optimal input trajectory.

Fast ion stabilization of the ion temperature gradient driven modes in the Joint European Torus hybrid-scenario plasmas: a trigger mechanism for internal transport barrier formation

NASA Astrophysics Data System (ADS)

Romanelli, M.; Zocco, A.; Crisanti, F.; Contributors, JET-EFDA

2010-04-01

Understanding and modelling turbulent transport in thermonuclear fusion plasmas are crucial for designing and optimizing the operational scenarios of future fusion reactors. In this context, plasmas exhibiting state transitions, such as the formation of an internal transport barrier (ITB), are particularly interesting since they can shed light on transport physics and offer the opportunity to test different turbulence suppression models. In this paper, we focus on the modelling of ITB formation in the Joint European Torus (JET) [1] hybrid-scenario plasmas, where, due to the monotonic safety factor profile, magnetic shear stabilization cannot be invoked to explain the transition. The turbulence suppression mechanism investigated here relies on the increase in the plasma pressure gradient in the presence of a minority of energetic ions. Microstability analysis of the ion temperature gradient driven modes (ITG) in the presence of a fast-hydrogen minority shows that energetic ions accelerated by the ion cyclotron resonance heating (ICRH) system (hydrogen, nH,fast/nD,thermal up to 10%, TH,fast/TD,thermal up to 30) can increase the pressure gradient enough to stabilize the ITG modes driven by the gradient of the thermal ions (deuterium). Numerical analysis shows that, by increasing the temperature of the energetic ions, electrostatic ITG modes are gradually replaced by nearly electrostatic modes with tearing parity at progressively longer wavelengths. The growth rate of the microtearing modes is found to be lower than that of the ITG modes and comparable to the local E × B-velocity shearing rate. The above mechanism is proposed as a possible trigger for the formation of ITBs in this type of discharges.

Ion heating in a plasma focus

NASA Technical Reports Server (NTRS)

Hohl, F.; Gary, S. P.

1974-01-01

Ion acceleration and heating in a plasma focus were investigated by the numerical integration of the three-dimensional equations of motion. The electric and magnetic fields given were derived from experimental data. The results obtained show that during the collapse phase of focus formation, ions are efficiently heated to temperatures of several keV. During the phase of rapid current reduction, ions are accelerated to large velocities in the axial direction. The results obtained with the model are in general agreement with experimental results.

High efficiency ion beam accelerator system

NASA Technical Reports Server (NTRS)

Aston, G.

1981-01-01

An ion accelerator system that successfully combines geometrical and electrostatic focusing principles is presented. This accelerator system uses thin, concave, multiple-hole, closely spaced graphite screen and focusing grids which are coupled to single slot accelerator and decelerator grids to provide high ion extraction efficiency and good focusing. Tests with the system showed a substantial improvement in ion beam current density and collimation as compared with a Pierce electrode configuration. Durability of the thin graphite screen and focusing grids has been proven, and tests are being performed to determine the minimum screen and focusing grid spacing and thickness required to extract the maximum reliable beam current density. Compared with present neutral beam injector accelerator systems, this one has more efficient ion extraction, easier grid alignment, easier fabrication, a less cumbersome design, and the capacity to be constructed in a modular fashion. Conceptual neutral beam injector designs using this modular approach have electrostatic beam deflection plates downstream of each module.

Component-/structure-dependent elasticity of solid electrolyte interphase layer in Li-ion batteries: Experimental and computational studies

NASA Astrophysics Data System (ADS)

Shin, Hosop; Park, Jonghyun; Han, Sangwoo; Sastry, Ann Marie; Lu, Wei

2015-03-01

The mechanical instability of the Solid Electrolyte Interphase (SEI) layer in lithium ion (Li-ion) batteries causes significant side reactions resulting in Li-ion consumption and cell impedance rise by forming further SEI layers, which eventually leads to battery capacity fade and power fade. In this paper, the composition-/structure-dependent elasticity of the SEI layer is investigated via Atomic Force Microscopy (AFM) measurements coupled with X-ray Photoelectron Spectroscopy (XPS) analysis, and atomistic calculations. It is observed that the inner layer is stiffer than the outer layer. The measured Young's moduli are mostly in the range of 0.2-4.5 GPa, while some values above 80 GPa are also observed. This wide variation of the observed elastic modulus is elucidated by atomistic calculations with a focus on chemical and structural analysis. The numerical analysis shows the Young's moduli range from 2.4 GPa to 58.1 GPa in the order of the polymeric, organic, and amorphous inorganic components. The crystalline inorganic component (LiF) shows the highest value (135.3 GPa) among the SEI species. This quantitative observation on the elasticity of individual components of the SEI layer must be essential to analyzing the mechanical behavior of the SEI layer and to optimizing and controlling it.

Rational Design of Porous Covalent Triazine-Based Framework Composites as Advanced Organic Lithium-Ion Battery Cathodes.

PubMed

Yuan, Ruoxin; Kang, Wenbin; Zhang, Chuhong

2018-06-02

In an effort to explore the use of organic high-performance lithium ion battery cathodes as an alternative to resolve the current bottleneck hampering the development of their inorganic counterparts, a rational strategy focusing on the optimal composition of covalent triazine-based frameworks (CTFs) with carbon-based materials of varied dimensionalities is delineated. Two-dimensional reduced graphene oxide (rGO) with a compatible structural conformation with the layered CTF is the most suitable scaffold for the tailored mesopores in the polymeric framework, providing outstanding energy storage ability. Through facile ionothermal synthesis and structure engineering, the obtained CTF-rGO composite possesses a high specific surface area of 1357.27 m²/g, and when used as a lithium ion battery cathode it delivers a large capacity of 235 mAh/g in 80 cycles at 0.1 A/g along with a stable capacity of 127 mAh/g over 2500 cycles at 5 A/g. The composite with modified pore structure shows drastically improved performance compared to a pristine CTF, especially at large discharge currents. The CTF-rGO composite with excellent capacity, stability, and rate performance shows great promise as an emerging high-performance cathode that could revolutionize the conventional lithium-ion battery industry.

WE-FG-BRB-04: RBEs for Human Lung Cancer Cells Exposed to Protons and Heavier Ions: Implications for Clinical Use of Charged Particles in Cancer Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Held, K.

The physical pattern of energy deposition and the enhanced relative biological effectiveness (RBE) of protons and carbon ions compared to photons offer unique and not fully understood or exploited opportunities to improve the efficacy of radiation therapy. Variations in RBE within a pristine or spread out Bragg peak and between particle types may be exploited to enhance cell killing in target regions without a corresponding increase in damage to normal tissue structures. In addition, the decreased sensitivity of hypoxic tumors to photon-based therapies may be partially overcome through the use of more densely ionizing radiations. These and other differences betweenmore » particle and photon beams may be used to generate biologically optimized treatments that reduce normal tissue complications. In this symposium, speakers will examine the impact of the RBE of charged particles on measurable biological endpoints, treatment plan optimization, and the prediction or retrospective assessment of treatment outcomes. In particular, an AAPM task group was formed to critically examine the evidence for a spatially-variant RBE in proton therapy. Current knowledge of proton RBE variation with respect to dose, biological endpoint, and physics parameters will be reviewed. Further, the clinical relevance of these variations will be discussed. Recent work focused on improving simulations of radiation physics and biological response in proton and carbon ion therapy will also be presented. Finally, relevant biology research and areas of research needs will be highlighted, including the dependence of RBE on genetic factors including status of DNA repair pathways, the sensitivity of cancer stem-like cells to charged particles, the role of charged particles in hypoxic tumors, and the importance of fractionation effects. In addition to the physical advantages of protons and more massive ions over photons, the future application of biologically optimized treatment plans and their potential to provide higher levels of local tumor control and improved normal tissue sparing will be discussed. Learning Objectives: To assess whether the current practice of a constant RBE of 1.1 should be revised or maintained in proton therapy and to evaluate the potential clinical consequences of delivering RBE-weighted dose distributions based on variable RBE To review current research on biological models used to predict the increased biological effectiveness of proton and carbon ions to help move towards a practical understanding and implementation of biological optimization in particle therapy To discuss potential differences in biological mechanisms between photons and charged particles (light and heavy ions) that could impact clinical cancer therapy H. Paganetti, NCI U19 CA21239D. Grosshans, Our research is supported by the NCIK. Held, Funding Support: National Cancer Institute of the National Institutes of Health, USA, under Award Number R21CA182259 and Federal Share of Program Income Earned by Massachusetts General Hospital on C06CA059267, Proton Therapy Research and Treatment Center.« less

Optimization of the molecular dynamics method for simulations of DNA and ion transport through biological nanopores.

PubMed

Wells, David B; Bhattacharya, Swati; Carr, Rogan; Maffeo, Christopher; Ho, Anthony; Comer, Jeffrey; Aksimentiev, Aleksei

2012-01-01

Molecular dynamics (MD) simulations have become a standard method for the rational design and interpretation of experimental studies of DNA translocation through nanopores. The MD method, however, offers a multitude of algorithms, parameters, and other protocol choices that can affect the accuracy of the resulting data as well as computational efficiency. In this chapter, we examine the most popular choices offered by the MD method, seeking an optimal set of parameters that enable the most computationally efficient and accurate simulations of DNA and ion transport through biological nanopores. In particular, we examine the influence of short-range cutoff, integration timestep and force field parameters on the temperature and concentration dependence of bulk ion conductivity, ion pairing, ion solvation energy, DNA structure, DNA-ion interactions, and the ionic current through a nanopore.

Optimization of a low noise detection circuit for probing the structure of damage cascades with IBIC

DOE PAGES

Auden, Elizabeth C.; Doyle, Barney L.; Bielejec, Edward; ...

2015-06-18

Optimal detector / pre-amplifier combinations have been identified for the use of light ion IBIC (ion beam induced charge) to probe the physical structure of electrically active defects in damage cascades caused by heavy ion implantation. The ideal detector must have a sufficiently thin dead layer that incident ions will produce the majority of damage cascades in the depletion region of the detector rather than the dead layer. Detector and circuit noise must be low enough to detect the implantation of a single heavy ion as well as the decrease in the light ion IBIC signal caused by Shockley-Read-Hall recombinationmore » when the beam scans regions of the detector damaged by the heavy ion. The IBIC signals from three detectors irradiated with 750 keV He⁺ ions are measured with commercial and bespoke charge sensitive pre-amplifiers to identify the combination with the lowest noise.« less

Voltage sweep ion mobility spectrometry.

PubMed

Davis, Eric J; Williams, Michael D; Siems, William F; Hill, Herbert H

2011-02-15

Ion mobility spectrometry (IMS) is a rapid, gas-phase separation technique that exhibits excellent separation of ions as a standalone instrument. However, IMS cannot achieve optimal separation power with both small and large ions simultaneously. Similar to the general elution problem in chromatography, fast ions are well resolved using a low electric field (50-150 V/cm), whereas slow drifting molecules are best separated using a higher electric field (250-500 V/cm). While using a low electric field, IMS systems tend to suffer from low ion transmission and low signal-to-noise ratios. Through the use a novel voltage algorithm, some of these effects can be alleviated. The electric field was swept from low to high while monitoring a specific drift time, and the resulting data were processed to create a 'voltage-sweep' spectrum. If an optimal drift time is calculated for each voltage and scanned simultaneously, a spectrum may be obtained with optimal separation throughout the mobility range. This increased the resolving power up to the theoretical maximum for every peak in the spectrum and extended the peak capacity of the IMS system, while maintaining accurate drift time measurements. These advantages may be extended to any IMS, requiring only a change in software.

Sub-micron resolution of localized ion beam induced charge reduction in silicon detectors damaged by heavy ions

DOE PAGES

Auden, Elizabeth C.; Pacheco, Jose L.; Bielejec, Edward; ...

2015-12-01

In this study, displacement damage reduces ion beam induced charge (IBIC) through Shockley-Read-Hall recombination. Closely spaced pulses of 200 keV Si ++ ions focused in a 40 nm beam spot are used to create damage cascades within 0.25 μm 2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of 200 keV Si ++ ions and 60 keV Li + ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions.

Sub-micron resolution of localized ion beam induced charge reduction in silicon detectors damaged by heavy ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auden, Elizabeth C.; Pacheco, Jose L.; Bielejec, Edward

In this study, displacement damage reduces ion beam induced charge (IBIC) through Shockley-Read-Hall recombination. Closely spaced pulses of 200 keV Si ++ ions focused in a 40 nm beam spot are used to create damage cascades within 0.25 μm 2 areas. Damaged areas are detected through contrast in IBIC signals generated with focused ion beams of 200 keV Si ++ ions and 60 keV Li + ions. IBIC signal reduction can be resolved over sub-micron regions of a silicon detector damaged by as few as 1000 heavy ions.

Ion implantation for deterministic single atom devices

NASA Astrophysics Data System (ADS)

Pacheco, J. L.; Singh, M.; Perry, D. L.; Wendt, J. R.; Ten Eyck, G.; Manginell, R. P.; Pluym, T.; Luhman, D. R.; Lilly, M. P.; Carroll, M. S.; Bielejec, E.

2017-12-01

We demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.

Ion implantation for deterministic single atom devices

DOE PAGES

Pacheco, J. L.; Singh, M.; Perry, D. L.; ...

2017-12-04

Here, we demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.

Chemical fractionation and speciation modelling for optimization of ion-exchange processes to recover palladium from industrial wastewater.

PubMed

Folens, K; Van Hulle, S; Vanhaecke, F; Du Laing, G

2016-01-01

Palladium is used in several industrial applications and, given its high intrinsic value, intense efforts are made to recover the element. In this hydrometallurgic perspective, ion-exchange (IEX) technologies are principal means. Yet, without incorporating the chemical and physical properties of the Pd present in real, plant-specific conditions, the recovery cannot reach its technical nor economic optimum. This study characterized a relevant Pd-containing waste stream of a mirror manufacturer to provide input for a speciation model, predicting the Pd speciation as a function of pH and chloride concentration. Besides the administered neutral PdCl2 form, both positively and negatively charged [PdCln](2-n) species occur depending on the chloride concentration in solution. Purolite C100 and Relite 2AS IEX resins were selected and applied in combination with other treatment steps to optimize the Pd recovery. A combination of the cation and anion exchange resins was found successful to quantitatively recover Pd. Given the fact that Pd was also primarily associated with particles, laboratory-scale experiments focused on physical removal of the Pd-containing flow were conducted, which showed that particle-bound Pd can already be removed by physical pre-treatment prior to IEX, while the ionic fraction remains fully susceptible to the IEX mechanism.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pacheco, J. L.; Singh, M.; Perry, D. L.

Here, we demonstrate a capability of deterministic doping at the single atom level using a combination of direct write focused ion beam and solid-state ion detectors. The focused ion beam system can position a single ion to within 35 nm of a targeted location and the detection system is sensitive to single low energy heavy ions. This platform can be used to deterministically fabricate single atom devices in materials where the nanostructure and ion detectors can be integrated, including donor-based qubits in Si and color centers in diamond.

Ion acceleration in shell cylinders irradiated by a short intense laser pulse

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreev, A.; ELI-ALPS, Szeged; Platonov, K.

The interaction of a short high intensity laser pulse with homo and heterogeneous shell cylinders has been analyzed using particle-in-cell simulations and analytical modeling. We show that the shell cylinder is proficient of accelerating and focusing ions in a narrow region. In the case of shell cylinder, the ion energy exceeds the ion energy for a flat target of the same thickness. The constructed model enables the evaluation of the ion energy and the number of ions in the focusing region.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carlson, D.

The physical pattern of energy deposition and the enhanced relative biological effectiveness (RBE) of protons and carbon ions compared to photons offer unique and not fully understood or exploited opportunities to improve the efficacy of radiation therapy. Variations in RBE within a pristine or spread out Bragg peak and between particle types may be exploited to enhance cell killing in target regions without a corresponding increase in damage to normal tissue structures. In addition, the decreased sensitivity of hypoxic tumors to photon-based therapies may be partially overcome through the use of more densely ionizing radiations. These and other differences betweenmore » particle and photon beams may be used to generate biologically optimized treatments that reduce normal tissue complications. In this symposium, speakers will examine the impact of the RBE of charged particles on measurable biological endpoints, treatment plan optimization, and the prediction or retrospective assessment of treatment outcomes. In particular, an AAPM task group was formed to critically examine the evidence for a spatially-variant RBE in proton therapy. Current knowledge of proton RBE variation with respect to dose, biological endpoint, and physics parameters will be reviewed. Further, the clinical relevance of these variations will be discussed. Recent work focused on improving simulations of radiation physics and biological response in proton and carbon ion therapy will also be presented. Finally, relevant biology research and areas of research needs will be highlighted, including the dependence of RBE on genetic factors including status of DNA repair pathways, the sensitivity of cancer stem-like cells to charged particles, the role of charged particles in hypoxic tumors, and the importance of fractionation effects. In addition to the physical advantages of protons and more massive ions over photons, the future application of biologically optimized treatment plans and their potential to provide higher levels of local tumor control and improved normal tissue sparing will be discussed. Learning Objectives: To assess whether the current practice of a constant RBE of 1.1 should be revised or maintained in proton therapy and to evaluate the potential clinical consequences of delivering RBE-weighted dose distributions based on variable RBE To review current research on biological models used to predict the increased biological effectiveness of proton and carbon ions to help move towards a practical understanding and implementation of biological optimization in particle therapy To discuss potential differences in biological mechanisms between photons and charged particles (light and heavy ions) that could impact clinical cancer therapy H. Paganetti, NCI U19 CA21239D. Grosshans, Our research is supported by the NCIK. Held, Funding Support: National Cancer Institute of the National Institutes of Health, USA, under Award Number R21CA182259 and Federal Share of Program Income Earned by Massachusetts General Hospital on C06CA059267, Proton Therapy Research and Treatment Center.« less

Optimizing the multicycle subrotational internal cooling of diatomic molecules

NASA Astrophysics Data System (ADS)

Aroch, A.; Kallush, S.; Kosloff, R.

2018-05-01

Subrotational cooling of the AlH+ ion to the miliKelvin regime, using optimally shaped pulses, is computed. The coherent electromagnetic fields induce purity-conserved transformations and do not change the sample temperature. A decrease in a sample temperature, manifested by an increase of purity, is achieved by the complementary uncontrolled spontaneous emission which changes the entropy of the system. We employ optimal control theory to find a pulse that stirs the system into a population configuration that will result in cooling, upon multicycle excitation-emission steps. The obtained optimal transformation was shown capable to cool molecular ions to the subkelvins regime.

Monte Carlo calculations of electron beam quality conversion factors for several ion chamber types.

PubMed

Muir, B R; Rogers, D W O

2014-11-01

To provide a comprehensive investigation of electron beam reference dosimetry using Monte Carlo simulations of the response of 10 plane-parallel and 18 cylindrical ion chamber types. Specific emphasis is placed on the determination of the optimal shift of the chambers' effective point of measurement (EPOM) and beam quality conversion factors. The EGSnrc system is used for calculations of the absorbed dose to gas in ion chamber models and the absorbed dose to water as a function of depth in a water phantom on which cobalt-60 and several electron beam source models are incident. The optimal EPOM shifts of the ion chambers are determined by comparing calculations of R50 converted from I50 (calculated using ion chamber simulations in phantom) to R50 calculated using simulations of the absorbed dose to water vs depth in water. Beam quality conversion factors are determined as the calculated ratio of the absorbed dose to water to the absorbed dose to air in the ion chamber at the reference depth in a cobalt-60 beam to that in electron beams. For most plane-parallel chambers, the optimal EPOM shift is inside of the active cavity but different from the shift determined with water-equivalent scaling of the front window of the chamber. These optimal shifts for plane-parallel chambers also reduce the scatter of beam quality conversion factors, kQ, as a function of R50. The optimal shift of cylindrical chambers is found to be less than the 0.5 rcav recommended by current dosimetry protocols. In most cases, the values of the optimal shift are close to 0.3 rcav. Values of kecal are calculated and compared to those from the TG-51 protocol and differences are explained using accurate individual correction factors for a subset of ion chambers investigated. High-precision fits to beam quality conversion factors normalized to unity in a beam with R50 = 7.5 cm (kQ (')) are provided. These factors avoid the use of gradient correction factors as used in the TG-51 protocol although a chamber dependent optimal shift in the EPOM is required when using plane-parallel chambers while no shift is needed with cylindrical chambers. The sensitivity of these results to parameters used to model the ion chambers is discussed and the uncertainty related to the practical use of these results is evaluated. These results will prove useful as electron beam reference dosimetry protocols are being updated. The analysis of this work indicates that cylindrical ion chambers may be appropriate for use in low-energy electron beams but measurements are required to characterize their use in these beams.

The new confocal heavy ion microprobe beamline at ANSTO: The first microprobe resolution tests and applications for elemental imaging and analysis

NASA Astrophysics Data System (ADS)

Pastuovic, Z.; Siegele, R.; Cohen, D. D.; Mann, M.; Ionescu, M.; Button, D.; Long, S.

2017-08-01

The Centre for Accelerator Science facility at ANSTO has been expanded with the new NEC 6 MV ;SIRIUS; accelerator system in 2015. In this paper we present a detailed description of the new nuclear microprobe-Confocal Heavy Ion Micro-Probe (CHIMP) together with results of the microprobe resolution testing and the elemental analysis performed on typical samples of mineral ore deposits and hyper-accumulating plants regularly measured at ANSTO. The CHIMP focusing and scanning systems are based on the OM-150 Oxford quadrupole triplet and the OM-26 separated scan-coil doublet configurations. A maximum ion rigidity of 38.9 amu-MeV was determined for the following nuclear microprobe configuration: the distance from object aperture to collimating slits of 5890 mm, the working distance of 165 mm and the lens bore diameter of 11 mm. The overall distance from the object to the image plane is 7138 mm. The CHIMP beamline has been tested with the 3 MeV H+ and 6 MeV He2+ ion beams. The settings of the object and collimating apertures have been optimized using the WinTRAX simulation code for calculation of the optimum acceptance settings in order to obtain the highest possible ion current for beam spot sizes of 1 μm and 5 μm. For optimized aperture settings of the CHIMP the beam brightness was measured to be ∼0.9 pA μm-2 mrad-2 for 3 MeV H+ ions, while the brightness of ∼0.4 pA μm-2 mrad-2 was measured for 6 MeV He2+ ions. The smallest beam sizes were achieved using a microbeam with reduced particle rate of 1000 Hz passing through the object slit apertures several micrometers wide. Under these conditions a spatial resolution of ∼0.6 μm × 1.5 μm for 3 MeV H+ and ∼1.8 μm × 1.8 μm for 6 MeV He2+ microbeams in horizontal (and vertical) dimension has been achieved. The beam sizes were verified using STIM imaging on 2000 and 1000 mesh Cu electron microscope grids.

Studies of Ion Acceleration from Thin Solid-Density Targets on High-Intensity Lasers

NASA Astrophysics Data System (ADS)

Willis, Christopher R.

Over the past two decades, a number of experiments have been performed demonstrating the acceleration of ions from the interaction of an intense laser pulse with a thin, solid density target. These ions are accelerated by quasi-static electric fields generated by energetic electrons produced at the front of the target, resulting in ion energies up to tens of MeV. These ions have been widely studied for a variety of potential applications ranging from treatment of cancer to the production of neutrons for advanced radiography techniques. However, realization of these applications will require further optimization of the maximum energy, spectrum, or species of the accelerated ions, which has been a primary focus of research to date. This thesis presents two experiments designed to optimize several characteristics of the accelerated ion beam. The first of these experiments took place on the GHOST laser system at the University of Texas at Austin, and was designed to demonstrate reliable acceleration of deuterium ions, as needed for the most efficient methods of neutron generation from accelerated ions. This experiment leveraged cryogenically cooled targets coated in D2 O ice to suppress the protons which typically dominate the accelerated ions, producing as many as 2 x 1010 deuterium ions per 1 J laser shot, exceeding the proton yield by an average ratio of 5:1. The second major experiment in this work was performed on the Scarlet laser system at The Ohio State University, and studied the accelerated ion energy, yield, and spatial distribution as a function of the target thickness. In principle, the peak energy increases with decreasing target thickness, with the thinnest targets accessing additional acceleration mechanisms which provide favorable scaling with the laser intensity. However, laser prepulse characteristics provide a lower bound for the target thickness, yielding an optimum target thickness for ion acceleration which is dependent on the laser system. This experiment utilized new liquid crystal film targets developed at OSU, which may be formed at variable thicknesses from tens of nanometers to several microns. On this experiment, an optimum ion energy and flux was reached for targets of 600-900 nm, providing a peak proton energy of 24 MeV, and total ion flux of > 109 protons over 3.4 MeV from 5.5 J of laser energy at an intensity of 1 x 1020 W cm -2. The primary ion diagnostics for these two experiments are described in detail, including the analysis techniques needed to extract absolutely calibrated spatial and spectral distributions of the accelerated ions. Additionally, a new technique for target alignment is presented, providing repeatable target alignment on the micron scale. This allows for a repeatable laser intensity on target, allowing improved shot to shot consistency on high intensity experiments. In addition to these two experiments, work on the upgrade and characterization of the 400 TW Scarlet laser is discussed, including several calculations critical to the design and upgrade of the laser system, as well as prepulse characterization needed for experiments on thin targets.

Feasible conversion of solid waste bauxite tailings into highly crystalline 4A zeolite with valuable application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Dongyang; Wang, Zhendong; Guo, Min

2014-11-15

Highlights: • Concept to convert waste to valuable product is carried out in this study. • An industrially feasible and cost-effective approach was developed and optimized. • Highly crystalline and well-defined zeolite was produced under moderate conditions. • The zeolite derived from the bauxite tailings displayed high ion exchange capacity. • Bauxite tailings have potential application in heavy metal ions adsorbent. - Abstract: Bauxite tailings are a major type of solid wastes generated in the flotation process. The waste by-products caused significant environmental impact. To lessen this hazardous effect from poisonous mine tailings, a feasible and cost-effective solution was conceivedmore » and implemented. Our approach focused on reutilization of the bauxite tailings by converting it to 4A zeolite for reuse in diverse applications. Three steps were involved in the bauxite conversion: wet-chemistry, alkali fusion, and crystallization to remove impurities and to prepare porous 4A zeolite. It was found that the cubic 4A zeolite was single phase, in high purity, with high crystallinity and well-defined structure. Importantly, the 4A zeolite displayed maximum calcium ion exchange capacity averaged at 296 mg CaCO{sub 3}/g, comparable to commercially-available zeolite (310 mg CaCO{sub 3}/g) exchange capacity. Base on the optimal synthesis condition, the reaction yield of zeolite 4A from bauxite tailings achieved to about 38.43%, hence, this study will provide a new paradigm for remediation of bauxite tailings, further mitigating the environmental and health care concerns, particularly in the mainland of PR China.« less

Can neutral analytes be concentrated by transient isotachophoresis in micellar electrokinetic chromatography and how much?

PubMed

Matczuk, Magdalena; Foteeva, Lidia S; Jarosz, Maciej; Galanski, Markus; Keppler, Bernhard K; Hirokawa, Takeshi; Timerbaev, Andrei R

2014-06-06

Transient isotachophoresis (tITP) is a versatile sample preconcentration technique that uses ITP to focus electrically charged analytes at the initial stage of CE analysis. However, according to the ruling principle of tITP, uncharged analytes are beyond its capacity while being separated and detected by micellar electrokinetic chromatography (MEKC). On the other hand, when these are charged micelles that undergo the tITP focusing, one can anticipate the concentration effect, resulting from the formation of transient micellar stack at moving sample/background electrolyte (BGE) boundary, which increasingly accumulates the analytes. This work expands the enrichment potential of tITP for MEKC by demonstrating the quantitative analysis of uncharged metal-based drugs from highly saline samples and introducing to the BGE solution anionic surfactants and buffer (terminating) co-ions of different mobility and concentration to optimize performance. Metallodrugs of assorted lipophilicity were chosen so as to explore whether their varying affinity toward micelles plays the role. In addition to altering the sample and BGE composition, optimization of the detection capability was achieved due to fine-tuning operational variables such as sample volume, separation voltage and pressure, etc. The results of optimization trials shed light on the mechanism of micellar tITP and render effective determination of selected drugs in human urine, with practical limits of detection using conventional UV detector. Copyright © 2014 Elsevier B.V. All rights reserved.

Optimization and adsorption kinetic studies of aqueous manganese ion removal using chitin extracted from shells of edible Philippine crabs

NASA Astrophysics Data System (ADS)

Quimque, Mark Tristan J.; Jimenez, Marvin C.; Acas, Meg Ina S.; Indoc, Danrelle Keth L.; Gomez, Enjelyn C.; Tabuñag, Jenny Syl D.

2017-01-01

Manganese is a common contaminant in drinking water along with other metal pollutants. This paper investigates the use of chitin, extracted from crab shells obtained as restaurant throwaway, as an adsorbent in removing manganese ions from aqueous medium. In particular, this aims to optimize the adsorption parameters and look into the kinetics of the process. The adsorption experiments done in this study employed the batch equilibration method. In the optimization, the following parameters were considered: pH and concentration of Mn (II) sorbate solution, particle size and dosage of adsorbent chitin, and adsorbent-adsorbate contact time. At the optimal condition, the order of the adsorption reaction was estimated using kinetic models which describes the process best. It was found out that the adsorption of aqueous Mn (II) ions onto chitin obeys the pseudo-second order model. This model assumes that the adsorption occurred via chemisorption

Charge breeding simulations for radioactive ion beam production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Variale, V.; Raino, A. C.; Clauser, T.

2012-02-15

The charge breeding technique is used for radioactive ion beam (RIB) production in order of optimizing the re-acceleration of the radioactive element ions produced by a primary beam in a thick target. Charge breeding is achieved by means of a device capable of increasing the ion charge state from 1+ to a desired value n+. In order to get high intensity RIB, experiments with charge breeding of very high efficiency could be required. To reach this goal, the charge breeding simulation could help to optimize the high charge state production efficiency by finding more proper parameters for the radioactive 1+more » ions. In this paper a device based on an electron beam ion source (EBIS) is considered. In order to study that problem, a code already developed for studying the ion selective containment in an EBIS with RF quadrupoles, BRICTEST, has been modified to simulate the ion charge state breeding rate for different 1+ ion injection conditions. Particularly, the charge breeding simulations for an EBIS with a hollow electron beam have been studied.« less

Atomic-scale thermocapillary flow in focused ion beam milling

NASA Astrophysics Data System (ADS)

Das, Kallol; Johnson, Harley; Freund, Jonathan

2016-11-01

Focused ion beams (FIB) offer an attractive tool for nanometer-scale manufacturing and material processing, particularly because they can be focused to a few nanometer diameter spot. This motivates their use for many applications, such as sample preparation for transmission electron microscopy (TEM), forming nanometer scale pores in thin films for DNA sequencing. Despite its widespread use, the specific mechanisms of FIB milling, especially at high ion fluxes for which significant phase change might occur, remains incompletely understood. Here we investigate the process of nanopore fabrication in thin Si films using molecular dynamics simulation where Ga+ ions are used as the focused ions. For a range of ion intensities in a realistic configuration, a recirculating melt region develops, which is seen to flow with a symmetrical pattern, counter to how it would flow were it is driven by the ion momentum flux. Such flow is potentially important for the shape and composition of the formed structures. Relevant stress scales and estimated physical properties of silicon under these extreme conditions support the importance thermocapillary effects. A continuum flow model with Marangoni forcing reproduces the flow.

Beam Profile Studies for a One Eighth Betatron Wavelength Final Focusing Cell Following Phase Mixed Transport

DTIC Science & Technology

1988-10-26

concentrated into this off- axis peak is then considered. Estimates of the source brightness ( extraction ion diode source current density divided by the square...radioactive contamination of the accelerator. One possible scheme for avoiding this problem is to use extraction geometry ion diodes to focus the ion beams...annular region. These results will be coupled to two simple models of extraction ion diodes to determihe the ion source brightness requirements. These

Ion Channel Modulators in Cystic Fibrosis.

PubMed

Gentzsch, Martina; Mall, Marcus A

2018-05-08

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and remains one of the most common life-shortening genetic diseases affecting the lung and other organs. CFTR functions as a cAMP-dependent anion channel that transports chloride and bicarbonate across epithelial surfaces and disruption of these ion transport processes plays a central role in the pathogenesis of CF. These findings provided the rationale for pharmacological modulation of ion transport, either by targeting mutant CFTR or alternative ion channels that can compensate for CFTR dysfunction, as a promising therapeutic approach. High throughput screening has supported the development of CFTR modulator compounds. CFTR correctors are designed to improve defective protein processing, trafficking and cell surface expression, whereas potentiators increase the activity of mutant CFTR at the cell surface. The approval of the first potentiator ivacaftor for the treatment of patients with specific CFTR mutations and, more recently the corrector lumacaftor in combination with ivacaftor for patients homozygous for the common F508del mutation, were major breakthroughs on the path to causal therapies for all patients with CF. In this review, we focus on recent developments and remaining challenges of CFTR-directed therapies, as well as modulators of other ion channels such as alternative chloride channels and the epithelial sodium channel (ENaC) as additional targets in CF lung disease. Further, we discuss how patient-derived precision medicine models may aid the translation of emerging next generation ion channel modulators from the laboratory to the clinic and tailor their use for optimal therapeutic benefits in individual patients with CF. Copyright © 2018. Published by Elsevier Inc.

Diagnostics of ion beam generated from a Mather type plasma focus device

NASA Astrophysics Data System (ADS)

Lim, L. K.; Ngoi, S. K.; Wong, C. S.; Yap, S. L.

2014-03-01

Diagnostics of ion beam emission from a 3 kJ Mather-type plasma focus device have been performed for deuterium discharge at low pressure regime. Deuterium plasma focus was found to be optimum at pressure of 0.2 mbar. The energy spectrum and total number of ions per shot from the pulsed ion beam are determined by using biased ion collectors, Faraday cup, and solid state nuclear track detector CR-39. Average energy of the ion beam obtained is about 60 keV. Total number of the ions has been determined to be in the order of 1011 per shot. Solid state nuclear track detectors (SSNTD) CR39 are employed to measure the particles at all angular direction from end on (0°) to side on (90°). Particle tracks are registered by SSNTD at 30° to 90°, except the one at the end-on 0°.

Design and Development of a Prototype Permanent Magnet for Focusing/Defocusing for Electron-Ion Colliders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wagner, Bob

Electron-ion colliders (EIC) have been identified as an ideal tool to study the next frontier of nuclear physics – the gluon force that holds the building blocks of matter together, and which is a fundamental component of the theory of Quantum Chromodynamics (QCD). Future electron-ion colliders under consideration can be based on the Energy Recovery Linac (ERL) architecture. The beam lines for this architecture could be built of the newly developed Non-Scaling Fixed Field Alternating Gradient (NS FFAG) structure, so that they can transfer multiple energies within the same aperture. This structure allows for the use of compact, economical quadupolemore » permanent magnets. In this SBIR, we propose to design and to manufacture prototype quadrupole permanent magnets of focusing/defocusing combined function for use in this beam line. For our SBIR project, we proposed to design and build the focusing/defocusing quadrupole with a gradient strength of 50 T/m and with a beam gap of 16mm. The proposed permanent magnet material is SmCo because of its higher radiation resistance as compared to NdBFe2. The use of permanent magnets will reduce the overall cost. For Phase I, we took a recent design by Dr. Dejan Trbojevic, and reran Tosca code on the design to optimize the iron yoke with respect to the thickness of SmCo. We then fabricated one prototype focusing/defocusing combined function quadruple and measured field quality dG/Go. Our plan for Phase II is that, based on our Phase I prototype experience, we shall improve the design and fabricate a production quadruple, and design and incorporate coils for skew dipoles and normal quadrupole correctors, etc. In addition, we shall fabricate enough quadrupoles for one cell. The development of quadrupole permanent magnets is of fundamental importance for there application in the future electron-ion colliders. This accelerator structure will also advance the development of muon accelerators and allow for the development of compact, simplified, less expensive proton accelerators which will promote their use in areas such as proton cancer therapy, and for high-power proton drivers for tritium and neutron production, waste transmutation, driving a sub-critical nuclear reactor to produce energy, cargo contain inspection, and radioisotope production. Proton cancer therapy has been identified as a particularly attractive and viable commercial application for the immediate future.« less

Time-resolved imaging of the MALDI linear-TOF ion cloud: direct visualization and exploitation of ion optical phenomena using a position- and time-sensitive detector.

PubMed

Ellis, Shane R; Soltwisch, Jens; Heeren, Ron M A

2014-05-01

In this study, we describe the implementation of a position- and time-sensitive detection system (Timepix detector) to directly visualize the spatial distributions of the matrix-assisted laser desorption ionization ion cloud in a linear-time-of-flight (MALDI linear-ToF) as it is projected onto the detector surface. These time-resolved images allow direct visualization of m/z-dependent ion focusing effects that occur within the ion source of the instrument. The influence of key parameters, namely extraction voltage (E(V)), pulsed-ion extraction (PIE) delay, and even the matrix-dependent initial ion velocity was investigated and were found to alter the focusing properties of the ion-optical system. Under certain conditions where the spatial focal plane coincides with the detector plane, so-called x-y space focusing could be observed (i.e., the focusing of the ion cloud to a small, well-defined spot on the detector). Such conditions allow for the stigmatic ion imaging of intact proteins for the first time on a commercial linear ToF-MS system. In combination with the ion-optical magnification of the system (~100×), a spatial resolving power of 11–16 μm with a pixel size of 550 nm was recorded within a laser spot diameter of ~125 μm. This study demonstrates both the diagnostic and analytical advantages offered by the Timepix detector in ToF-MS.

Migration of interfacial oxygen ions modulated resistive switching in oxide-based memory devices

NASA Astrophysics Data System (ADS)

Chen, C.; Gao, S.; Zeng, F.; Tang, G. S.; Li, S. Z.; Song, C.; Fu, H. D.; Pan, F.

2013-07-01

Oxides-based resistive switching memory induced by oxygen ions migration is attractive for future nonvolatile memories. Numerous works had focused their attentions on the sandwiched oxide materials for depressing the characteristic variations, but the comprehensive studies of the dependence of electrodes on the migration behavior of oxygen ions are overshadowed. Here, we investigated the interaction of various metals (Ni, Co, Al, Ti, Zr, and Hf) with oxygen atoms at the metal/Ta2O5 interface under electric stress and explored the effect of top electrode on the characteristic variations of Ta2O5-based memory device. It is demonstrated that chemically inert electrodes (Ni and Co) lead to the scattering switching characteristics and destructive gas bubbles, while the highly chemically active metals (Hf and Zr) formed a thick and dense interfacial intermediate oxide layer at the metal/Ta2O5 interface, which also degraded the resistive switching behavior. The relatively chemically active metals (Al and Ti) can absorb oxygen ions from the Ta2O5 film and avoid forming the problematic interfacial layer, which is benefit to the formation of oxygen vacancies composed conduction filaments in Ta2O5 film thus exhibit the minimum variations of switching characteristics. The clarification of oxygen ions migration behavior at the interface can lead further optimization of resistive switching performance in Ta2O5-based memory device and guide the rule of electrode selection for other oxide-based resistive switching memories.

Nano-SiC region formation in (100) Si-on-insulator substrate: Optimization of hot-C+-ion implantation process to improve photoluminescence intensity

NASA Astrophysics Data System (ADS)

Mizuno, Tomohisa; Omata, Yuhsuke; Kanazawa, Rikito; Iguchi, Yusuke; Nakada, Shinji; Aoki, Takashi; Sasaki, Tomokazu

2018-04-01

We experimentally studied the optimization of the hot-C+-ion implantation process for forming nano-SiC (silicon carbide) regions in a (100) Si-on-insulator substrate at various hot-C+-ion implantation temperatures and C+ ion doses to improve photoluminescence (PL) intensity for future Si-based photonic devices. We successfully optimized the process by hot-C+-ion implantation at a temperature of about 700 °C and a C+ ion dose of approximately 4 × 1016 cm-2 to realize a high intensity of PL emitted from an approximately 1.5-nm-thick C atom segregation layer near the surface-oxide/Si interface. Moreover, atom probe tomography showed that implanted C atoms cluster in the Si layer and near the oxide/Si interface; thus, the C content locally condenses even in the C atom segregation layer, which leads to SiC formation. Corrector-spherical aberration transmission electron microscopy also showed that both 4H-SiC and 3C-SiC nanoareas near both the surface-oxide/Si and buried-oxide/Si interfaces partially grow into the oxide layer, and the observed PL photons are mainly emitted from the surface SiC nano areas.

Optimization of NiFe2O4/rGO composite electrode for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Li, Chen; Wang, Xia; Li, Shandong; Li, Qiang; Xu, Jie; Liu, Xiaomin; Liu, Changkun; Xu, Yuanhong; Liu, Jingquan; Li, Hongliang; Guo, Peizhi; Zhao, Xiu Song

2017-09-01

The combination of carbon compositing and the proper choice of binders in one system offer an effective strategy for improving electrode performance for lithium ion batteries (LIBs). Here, we focus on the optimization of reduced graphene oxide content in NiFe2O4/reduced graphene oxide (abbreviated to NiFe2O4/rGO) composites and the proper choice of binders to enhance the cycling stability of the NiFe2O4 electrode. The NiFe2O4/rGO composites were fabricated by a hydrothermal-annealing method, in which the mean size of spinel NiFe2O4 nanoparticles was approximately 20 nm. When tested as anode materials for LIBs, the NiFe2O4/rGO electrodes with carboxymethylcellulose (CMC) binder exhibited excellent lithium-storage performance including high reversible capacity, good cycling durability and high-rate capability. The capacity could be retained as high as 1105 mAh g-1 at a current density of 100 mA g-1 for over 50 cycles, even cycled at higher current density of 1000 mA g-1, a capacity of 800 mAh g-1can be obtained, whereas the electrode with the polyvinylidene fluoride (PVDF) binder suffered from rapid capacity decay under the same test conditions. As a result, the NiFe2O4/rGO composites with CMC binder electrode in this work are promising as anodes for high-performance LIBs, resulting from the synergistic effect of optimal graphene content and proper choice of binder.

DOE Office of Scientific and Technical Information (OSTI.GOV)

He, W.; Zhao, H.W.; Liu, Zh.W.

To study the injection of additional electrons from an external electron gun into the plasma of a Penning ionization gauge (PIG) ion source, a test bench for the external electron-beam enhancement of the PIG (E-PIG) ion source was set up. A source magnet assembly was built to satisfy the request for magnetic field configuration of the E-PIG ion source. Numerical calculations have been done to optimize the magnetic field configuration so as to fit the primary electrons to be fed into the PIG discharge chamber along the spreading magnetic field lines. Many possible methods for improving the performance and stabilitymore » of the PIG ion source have been used in the E-PIG ion source, including the use of multicrystal LaB{sub 6} cathode and optimized axial magnetic field. This article presents a detailed design of the E-PIG ion source. Substantial enhancement of ion charge state is expected to be observed which demonstrates that the E-PIG is a viable alternative to other much more costly and difficult to operate devices for the production of intense ion beams of higher charge state.« less

Low energy, high power hydrogen neutral beam for plasma heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deichuli, P.; Davydenko, V.; Ivanov, A., E-mail: ivanov@inp.nsk.su

A high power, relatively low energy neutral beam injector was developed to upgrade of the neutral beam system of the gas dynamic trap device and C2-U experiment. The ion source of the injector produces a proton beam with the particle energy of 15 keV, current of up to 175 A, and pulse duration of a few milliseconds. The plasma emitter of the ion source is produced by superimposing highly ionized plasma jets from an array of four arc-discharge plasma generators. A multipole magnetic field produced with permanent magnets at the periphery of the plasma box is used to increase themore » efficiency and improve the uniformity of the plasma emitter. Multi-slit grids with 48% transparency are fabricated from bronze plates, which are spherically shaped to provide geometrical beam focusing. The focal length of the Ion Optical System (IOS) is 3.5 m and the initial beam diameter is 34 cm. The IOS geometry and grid potentials were optimized numerically to ensure accurate beam formation. The measured angular divergences of the beam are ±0.01 rad parallel to the slits and ±0.03 rad in the transverse direction.« less

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa.

PubMed

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa . Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg 2+ , Fe 2+ , and Zn 2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy.

Optimization of Culture Medium Enhances Viable Biomass Production and Biocontrol Efficacy of the Antagonistic Yeast, Candida diversa

PubMed Central

Liu, Jia; Li, Guangkun; Sui, Yuan

2017-01-01

Viable biomass production is a key determinant of suitability of antagonistic yeasts as potential biocontrol agents. This study investigated the effects of three metal ions (magnesium, ferrous, and zinc) on biomass production and viability of the antagonistic yeast, Candida diversa. Using response surface methodology to optimize medium components, a maximum biomass was obtained, when the collective Mg2+, Fe2+, and Zn2+ concentrations were adjusted in a minimal mineral (MM) medium. Compared with the unmodified MM, and three ion-deficient MM media, yeast cells cultured in the three ion-modified MM medium exhibited a lower level of cellular oxidative damage, and a higher level of antioxidant enzyme activity. A biocontrol assay indicated that C. diversa grown in the ion-modified MM exhibited the greatest level of control of gray mold on apple fruit. These results provide new information on culture medium optimization to grow yeast antagonists in order to improve biomass production and biocontrol efficacy. PMID:29089939

First experiments with the negative ion source NIO1.

PubMed

Cavenago, M; Serianni, G; De Muri, M; Agostinetti, P; Antoni, V; Baltador, C; Barbisan, M; Baseggio, L; Bigi, M; Cervaro, V; Degli Agostini, F; Fagotti, E; Kulevoy, T; Ippolito, N; Laterza, B; Minarello, A; Maniero, M; Pasqualotto, R; Petrenko, S; Poggi, M; Ravarotto, D; Recchia, M; Sartori, E; Sattin, M; Sonato, P; Taccogna, F; Variale, V; Veltri, P; Zaniol, B; Zanotto, L; Zucchetti, S

2016-02-01

Neutral Beam Injectors (NBIs), which need to be strongly optimized in the perspective of DEMO reactor, request a thorough understanding of the negative ion source used and of the multi-beamlet optics. A relatively compact radio frequency (rf) ion source, named NIO1 (Negative Ion Optimization 1), with 9 beam apertures for a total H(-) current of 130 mA, 60 kV acceleration voltage, was installed at Consorzio RFX, including a high voltage deck and an X-ray shield, to provide a test bench for source optimizations for activities in support to the ITER NBI test facility. NIO1 status and plasma experiments both with air and with hydrogen as filling gas are described. Transition from a weak plasma to an inductively coupled plasma is clearly evident for the former gas and may be triggered by rising the rf power (over 0.5 kW) at low pressure (equal or below 2 Pa). Transition in hydrogen plasma requires more rf power (over 1.5 kW).

Deuteron Beam Source Based on Mather Type Plasma Focus

NASA Astrophysics Data System (ADS)

Lim, L. K.; Yap, S. L.; Wong, C. S.; Zakaullah, M.

2013-04-01

A 3 kJ Mather type plasma focus system filled with deuterium gas is operated at pressure lower than 1 mbar. Operating the plasma focus in a low pressure regime gives a consistent ion beam which can make the plasma focus a reliable ion beam source. In our case, this makes a good deuteron beam source, which can be utilized for neutron generation by coupling a suitable target. This paper reports ion beam measurements obtained at the filling pressure of 0.05-0.5 mbar. Deuteron beam energy is measured by time of flight technique using three biased ion collectors. The ion beam energy variation with the filling pressure is investigated. Deuteron beam of up to 170 keV are obtained with the strongest deuteron beam measured at 0.1 mbar, with an average energy of 80 keV. The total number of deuterons per shot is in the order of 1018 cm-2.

Nanostructures by ion beams

NASA Astrophysics Data System (ADS)

Schmidt, B.

Ion beam techniques, including conventional broad beam ion implantation, ion beam synthesis and ion irradiation of thin layers, as well as local ion implantation with fine-focused ion beams have been applied in different fields of micro- and nanotechnology. The ion beam synthesis of nanoparticles in high-dose ion-implanted solids is explained as phase separation of nanostructures from a super-saturated solid state through precipitation and Ostwald ripening during subsequent thermal treatment of the ion-implanted samples. A special topic will be addressed to self-organization processes of nanoparticles during ion irradiation of flat and curved solid-state interfaces. As an example of silicon nanocrystal application, the fabrication of silicon nanocrystal non-volatile memories will be described. Finally, the fabrication possibilities of nanostructures, such as nanowires and chains of nanoparticles (e.g. CoSi2), by ion beam synthesis using a focused Co+ ion beam will be demonstrated and possible applications will be mentioned.

Front-end simulation of injector for terawatt accumulator.

PubMed

Kropachev, G N; Balabin, A I; Kolomiets, A A; Kulevoy, T V; Pershin, V I; Shumshurov, A V

2008-02-01

A terawatt accumulator (TWAC) accelerator/storage ring complex with the laser ion source is in progress at ITEP. The new injector I4 based on the radio frequency quadrupole (RFQ) and interdigital H-mode (IH) linear accelerator is under construction. The front end of the new TWAC injector consists of a laser ion source, an extraction system, and a low energy beam transport (LEBT). The KOBRA3-INP was used for the simulation and optimization of the ion source extraction system. The optimization parameter is the maximum brightness of the beam generated by the laser ion source. Also the KOBRA3-INP code was used for LEBT investigation. The LEBT based on electrostatic grid lenses is chosen for injector I4. The results of the extraction system and LEBT investigations for ion beam matching with RFQ are presented.

Piezoresistive Cantilever Performance—Part II: Optimization

PubMed Central

Park, Sung-Jin; Doll, Joseph C.; Rastegar, Ali J.; Pruitt, Beth L.

2010-01-01

Piezoresistive silicon cantilevers fabricated by ion implantation are frequently used for force, displacement, and chemical sensors due to their low cost and electronic readout. However, the design of piezoresistive cantilevers is not a straightforward problem due to coupling between the design parameters, constraints, process conditions, and performance. We systematically analyzed the effect of design and process parameters on force resolution and then developed an optimization approach to improve force resolution while satisfying various design constraints using simulation results. The combined simulation and optimization approach is extensible to other doping methods beyond ion implantation in principle. The optimization results were validated by fabricating cantilevers with the optimized conditions and characterizing their performance. The measurement results demonstrate that the analytical model accurately predicts force and displacement resolution, and sensitivity and noise tradeoff in optimal cantilever performance. We also performed a comparison between our optimization technique and existing models and demonstrated eight times improvement in force resolution over simplified models. PMID:20333323

Focusing of intense and divergent ion beams in a magnetic mass analyzer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jianlin, Ke; Changgeng, Zhou; Rui, Qiu

2014-07-15

A magnetic mass analyzer is used to determine the beam composition of a vacuum arc ion source. In the analyzer, we used the concentric multi-ring electrodes to focus the intense and divergent ion beams. We describe the principle, design, and the test results of the focusing device. The diameter of the beam profile is less than 20 mm when the accelerating voltage is 30 kV and the focusing voltage is about 2.0 kV. The focusing device has been successfully used in the magnetic mass analyzer to separate Ti{sup +}, Ti{sup 2+}, and Ti{sup 3+}.

Design study of a radio-frequency quadrupole for high-intensity beams

NASA Astrophysics Data System (ADS)

Bahng, Jungbae; Kim, Eun-San; Choi, Bong-Hyuk

2017-07-01

The Rare isotope Accelerator Of Newness (RAON) heavy-ion accelerator has been designed for the Rare Isotope Science Project (RISP) in Korea. The RAON will produce heavy-ion beams from 660-MeV-proton to 200-MeV/u-uranium with continuous wave (CW) power of 400 kW to support research in various scientific fields. Its system consists of an ECR ion source, LEBTs with 10 keV/u, CW RFQ accelerator with 81.25 MHz and 500 keV/u, a MEBT system, and a SC linac. In detail, the driver linac system consists of a Quarter Wave Resonator (QWR) section with 81.25 MHz and a Half Wave Resonator (HWR) section with 162.5 MHz, Linac-1, and a Spoke Cavity section with 325 MHz, Linac-2. These linacs have been designed to optimize the beam parameters to meet the required design goals. At the same time, a light-heavy ion accelerator with high-intensity beam, such as proton, deuteron, and helium beams, is required for experiments. In this paper, we present the design study of the high intensity RFQ for a deuteron beam with energies from 30 keV/u to 1.5 MeV/u and currents in the mA range. This system is composed of an Penning Ionization Gauge ion source, short LEBT with a RF deflector, and shared SC Linac. In order to increase acceleration efficiency in a short length with low cost, the 2nd harmonic of 162.5 MHz is applied as the operation frequency in the D+ RFQ design. The D+ RFQ is designed with 4.97 m, 1.52 bravery factor. Since it operates with 2nd harmonic frequency, the beam should be 50% of the duty factor while the cavity should be operated in CW mode, to protect the downstream linac system. We focus on avoiding emittance growth by the space-charge effect and optimizing the RFQ to achieve a high transmission and low emittance growth. Both the RFQ beam dynamics study and RFQ cavity design study for two and three dimensions will be discussed. Supported by Korea University Future Research Grant

Secondary ion collection and transport system for ion microprobe

DOEpatents

Ward, James W.; Schlanger, Herbert; McNulty, Jr., Hugh; Parker, Norman W.

1985-01-01

A secondary ion collection and transport system, for use with an ion microprobe, which is very compact and occupies only a small working distance, thereby enabling the primary ion beam to have a short focal length and high resolution. Ions sputtered from the target surface by the primary beam's impact are collected between two arcuate members having radii of curvature and applied voltages that cause only ions within a specified energy band to be collected. The collected ions are accelerated and focused in a transport section consisting of a plurality of spaced conductive members which are coaxial with and distributed along the desired ion path. Relatively high voltages are applied to alternate transport sections to produce accelerating electric fields sufficient to transport the ions through the section to an ion mass analyzer, while lower voltages are applied to the other transport sections to focus the ions and bring their velocity to a level compatible with the analyzing apparatus.

Nb3Sn superconducting magnets for electron cyclotron resonance ion sources.

PubMed

Ferracin, P; Caspi, S; Felice, H; Leitner, D; Lyneis, C M; Prestemon, S; Sabbi, G L; Todd, D S

2010-02-01

Electron cyclotron resonance (ECR) ion sources are an essential component of heavy-ion accelerators. Over the past few decades advances in magnet technology and an improved understanding of the ECR ion source plasma physics have led to remarkable performance improvements of ECR ion sources. Currently third generation high field superconducting ECR ion sources operating at frequencies around 28 GHz are the state of the art ion injectors and several devices are either under commissioning or under design around the world. At the same time, the demand for increased intensities of highly charged heavy ions continues to grow, which makes the development of even higher performance ECR ion sources a necessity. To extend ECR ion sources to frequencies well above 28 GHz, new magnet technology will be needed in order to operate at higher field and force levels. The superconducting magnet program at LBNL has been developing high field superconducting magnets for particle accelerators based on Nb(3)Sn superconducting technology for several years. At the moment, Nb(3)Sn is the only practical conductor capable of operating at the 15 T field level in the relevant configurations. Recent design studies have been focused on the possibility of using Nb(3)Sn in the next generation of ECR ion sources. In the past, LBNL has worked on the VENUS ECR, a 28 GHz source with solenoids and a sextupole made with NbTi operating at fields of 6-7 T. VENUS has now been operating since 2004. We present in this paper the design of a Nb(3)Sn ECR ion source optimized to operate at an rf frequency of 56 GHz with conductor peak fields of 13-15 T. Because of the brittleness and strain sensitivity of Nb(3)Sn, particular care is required in the design of the magnet support structure, which must be capable of providing support to the coils without overstressing the conductor. In this paper, we present the main features of the support structure, featuring an external aluminum shell pretensioned with water-pressurized bladders, and we analyze the expected coil stresses with a two-dimensional finite element mechanical model.

Optimized Wavelength-Tuned Nonlinear Frequency Conversion Using a Liquid Crystal Clad Waveguide

NASA Technical Reports Server (NTRS)

Stephen, Mark A. (Inventor)

2018-01-01

An optimized wavelength-tuned nonlinear frequency conversion process using a liquid crystal clad waveguide. The process includes implanting ions on a top surface of a lithium niobate crystal to form an ion implanted lithium niobate layer. The process also includes utilizing a tunable refractive index of a liquid crystal to rapidly change an effective index of the lithium niobate crystal.

Optimal quantum control of multimode couplings between trapped ion qubits for scalable entanglement.

PubMed

Choi, T; Debnath, S; Manning, T A; Figgatt, C; Gong, Z-X; Duan, L-M; Monroe, C

2014-05-16

We demonstrate entangling quantum gates within a chain of five trapped ion qubits by optimally shaping optical fields that couple to multiple collective modes of motion. We individually address qubits with segmented optical pulses to construct multipartite entangled states in a programmable way. This approach enables high-fidelity gates that can be scaled to larger qubit registers for quantum computation and simulation.

Radiocarbon measurements of small gaseous samples at CologneAMS

NASA Astrophysics Data System (ADS)

Stolz, A.; Dewald, A.; Altenkirch, R.; Herb, S.; Heinze, S.; Schiffer, M.; Feuerstein, C.; Müller-Gatermann, C.; Wotte, A.; Rethemeyer, J.; Dunai, T.

2017-09-01

A second SO-110 B (Arnold et al., 2010) ion source was installed at the 6 MV CologneAMS for the measurement of gaseous samples. For the gas supply a dedicated device from Ionplus AG was connected to the ion source. Special effort was devoted to determine optimized operation parameters for the ion source, which give a high carbon current output and a high 14C- yield. The latter is essential in cases when only small samples are available. Additionally a modified immersion lens and modified target pieces were tested and the target position was optimized.

Comprehensive hydrophilic interaction and ion-pair reversed-phase liquid chromatography for analysis of di- to deca-oligonucleotides.

PubMed

Li, Qin; Lynen, Frédéric; Wang, Jian; Li, Hanlin; Xu, Guowang; Sandra, Pat

2012-09-14

A comprehensive two-dimensional HPLC approach with a high degree of orthogonality was developed for analysis of di- to deca-oligonucleotides (ONs). Hydrophilic interaction liquid chromatography (HILIC) was used in the first dimension, and ion-pair reversed-phase liquid chromatography (IP-RPLC) was employed in the second dimension. The two dimensions were connected via a ten-port valve interface equipped with octadecyl silica (ODS) traps to immobilize and focus the ONs eluting from the first dimension prior to IP-RPLC separation. An aqueous make-up flow was used for effective trapping. The comprehensive two-dimensional HPLC system was optimized with a mixture consisting of 27 oligonucleotide standards. An overall chromatographic peak capacity of 500 was obtained. The use of the volatile buffer triethylamine acetate in the second dimension allowed straightforward coupling to electrospray ionization mass spectrometry (ESI-MS) and detection of each ON in the negative ionization mode. Copyright © 2011 Elsevier B.V. All rights reserved.

Dustbuster: a New Generation Impact-ionization Time-of-flight Mass Spectrometer for in situ Analysis of Cosmic Dust

NASA Astrophysics Data System (ADS)

Austin, D. E.; Ahrens, T. J.; Beauchamp, J. L.

2000-10-01

We have developed and tested a small impact-ionization time-of-flight mass spectrometer for analysis of cosmic dust, suitable for use on deep space missions. This mass spectrometer, named Dustbuster, incorporates a large target area and a reflectron, simultaneously optimizing mass resolution, sensitivity, and collection efficiency. Dust particles hitting the 65-cm2 target plate are partially ionized. The resulting ions are accelerated through a modified reflectron that focuses the ions in space and time to produce high-resolution spectra. The instrument, shown below, measures 10 x 10 x 20 cm, has a mass of 500 g, and consumes little power. Laser desorption ionization of metal and mineral samples (embedded in the impact plate) simulates particle impacts for instrument performance tests. Mass resolution in these experiments is near 200, permitting resolution of isotopes. The mass spectrometer can be combined with other instrument components to determine dust particle trajectories and sizes. This project was funded by NASA's Planetary Instrument Definition and Development Program.

The direct injection of intense ion beams from a high field electron cyclotron resonance ion source into a radio frequency quadrupole

NASA Astrophysics Data System (ADS)

Rodrigues, G.; Becker, R.; Hamm, R. W.; Baskaran, R.; Kanjilal, D.; Roy, A.

2014-02-01

The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magnetic field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged 238U40+ (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.

The direct injection of intense ion beams from a high field electron cyclotron resonance ion source into a radio frequency quadrupole.

PubMed

Rodrigues, G; Becker, R; Hamm, R W; Baskaran, R; Kanjilal, D; Roy, A

2014-02-01

The ion current achievable from high intensity ECR sources for highly charged ions is limited by the high space charge. This makes classical extraction systems for the transport and subsequent matching to a radio frequency quadrupole (RFQ) accelerator less efficient. The direct plasma injection (DPI) method developed originally for the laser ion source avoids these problems and uses the combined focusing of the gap between the ion source and the RFQ vanes (or rods) and the focusing of the rf fields from the RFQ penetrating into this gap. For high performance ECR sources that use superconducting solenoids, the stray magnetic field of the source in addition to the DPI scheme provides focusing against the space charge blow-up of the beam. A combined extraction/matching system has been designed for a high performance ECR ion source injecting into an RFQ, allowing a total beam current of 10 mA from the ion source for the production of highly charged (238)U(40+) (1.33 mA) to be injected at an ion source voltage of 60 kV. In this design, the features of IGUN have been used to take into account the rf-focusing of an RFQ channel (without modulation), the electrostatic field between ion source extraction and the RFQ vanes, the magnetic stray field of the ECR superconducting solenoid, and the defocusing space charge of an ion beam. The stray magnetic field is shown to be critical in the case of a matched beam.

Monte Carlo simulations of secondary electron emission due to ion beam milling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mahady, Kyle; Tan, Shida; Greenzweig, Yuval

We present a Monte Carlo simulation study of secondary electron emission resulting from focused ion beam milling of a copper target. The basis of this study is a simulation code which simulates ion induced excitation and emission of secondary electrons, in addition to simulating focused ion beam sputtering and milling. This combination of features permits the simulation of the interaction between secondary electron emission, and the evolving target geometry as the ion beam sputters material. Previous ion induced SE Monte Carlo simulation methods have been restricted to predefined target geometries, while the dynamic target in the presented simulations makes thismore » study relevant to image formation in ion microscopy, and chemically assisted ion beam etching, where the relationship between sputtering, and its effects on secondary electron emission, is important. We focus on a copper target, and validate our simulation against experimental data for a range of: noble gas ions, ion energies, ion/substrate angles and the energy distribution of the secondary electrons. We then provide a detailed account of the emission of secondary electrons resulting from ion beam milling; we quantify both the evolution of the yield as high aspect ratio valleys are milled, as well as the emission of electrons within these valleys that do not escape the target, but which are important to the secondary electron contribution to chemically assisted ion induced etching.« less

Optimizing Catalysts for Solar Fuel Production: Spectroscopic Characterization of the Key Reaction Intermediates

DTIC Science & Technology

2013-04-01

which freezes ions into well defined structures and coats them with an inert layer of weakly bound adducts. These cold aggregates were then...evaporation of the cryogenic solvent. Instrument development. Cryogenic ion processing. Cold ion spectroscopy. Trapped reaction intermediates U U U...spectrometer. The key advance incorporated into this instrument is the introduction of a cryogenic (10K) ion processing stage, where ions can be frozen

Diagnostics of ion beam generated from a Mather type plasma focus device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, L. K., E-mail: yapsl@um.edu.my; Ngoi, S. K., E-mail: yapsl@um.edu.my; Wong, C. S., E-mail: yapsl@um.edu.my

Diagnostics of ion beam emission from a 3 kJ Mather-type plasma focus device have been performed for deuterium discharge at low pressure regime. Deuterium plasma focus was found to be optimum at pressure of 0.2 mbar. The energy spectrum and total number of ions per shot from the pulsed ion beam are determined by using biased ion collectors, Faraday cup, and solid state nuclear track detector CR-39. Average energy of the ion beam obtained is about 60 keV. Total number of the ions has been determined to be in the order of 10{sup 11} per shot. Solid state nuclear trackmore » detectors (SSNTD) CR39 are employed to measure the particles at all angular direction from end on (0°) to side on (90°). Particle tracks are registered by SSNTD at 30° to 90°, except the one at the end-on 0°.« less

65nm OPC and design optimization by using simple electrical transistor simulation

NASA Astrophysics Data System (ADS)

Trouiller, Yorick; Devoivre, Thierry; Belledent, Jerome; Foussadier, Franck; Borjon, Amandine; Patterson, Kyle; Lucas, Kevin; Couderc, Christophe; Sundermann, Frank; Urbani, Jean-Christophe; Baron, Stanislas; Rody, Yves; Chapon, Jean-Damien; Arnaud, Franck; Entradas, Jorge

2005-05-01

In the context of 65nm logic technology where gate CD control budget requirements are below 5nm, it is mandatory to properly quantify the impact of the 2D effects on the electrical behavior of the transistor [1,2]. This study uses the following sequence to estimate the impact on transistor performance: 1) A lithographic simulation is performed after OPC (Optical Proximity Correction) of active and poly using a calibrated model at best conditions. Some extrapolation of this model can also be used to assess marginalities due to process window (focus, dose, mask errors, and overlay). In our case study, we mainly checked the poly to active misalignment effects. 2) Electrical behavior of the transistor (Ion, Ioff, Vt) is calculated based on a derivative spice model using the simulated image of the gate as an input. In most of the cases Ion analysis, rather than Vt or leakage, gives sufficient information for patterning optimization. We have demonstrated the benefit of this approach with two different examples: -design rule trade-off : we estimated the impact with and without misalignment of critical rules like poly corner to active distance, active corner to poly distance or minimum space between small transistor and big transistor. -Library standard cell debugging: we applied this methodology to the most critical one hundred transistors of our standard cell libraries and calculate Ion behavior with and without misalignment between active and poly. We compared two scanner illumination modes and two OPC versions based on the behavior of the one hundred transistors. We were able to see the benefits of one illumination, and also the improvement in the OPC maturity.

Vortex focusing of ions produced in corona discharge.

PubMed

Kolomiets, Yuri N; Pervukhin, Viktor V

2013-06-15

Completeness of the ion transportation into an analytical path defines the efficiency of ionization analysis techniques. This is of particular importance for atmospheric pressure ionization sources like corona discharge, electrospray, ionization with radioactive ((3)H, (63)Ni) isotopes that produce nonuniform spatial distribution of sample ions. The available methods of sample ion focusing are either efficient at reduced pressure (~1Torr) or feature high sample losses. This paper deals with experimental research into atmospheric pressure focusing of unipolar (positive) ions using a highly swirled air stream with a well-defined vortex core. Effects of electrical fields from corona needle and inlet capillary of mass spectrometer on collection efficiency is considered. We used a corona discharge to produce an ionized unipolar sample. It is shown experimentally that with an electrical field barrier efficient transportation and focusing of an ionized sample are possible only when a metal plate restricting the stream and provided with an opening covered with a grid is used. This gives a five-fold increase of the transportation efficiency. It is shown that the electric field barrier in the vortex sampling region reduces the efficiency of remote ionized sample transportation two times. The difference in the efficiency of light ion focusing observed may be explained by a high mobility and a significant effect of the electric field barrier upon them. It is possible to conclude based on the experimental data that the presence of the field barrier narrows considerably (more than by one and half) the region of the vortex sample ion focusing. Copyright © 2013 Elsevier B.V. All rights reserved.

Industrial ion source technology. [for ion beam etching, surface texturing, and deposition

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1977-01-01

Plasma probe surveys were conducted in a 30-cm source to verify that the uniformity in the ion beam is the result of a corresponding uniformity in the discharge-chamber plasma. A 15 cm permanent magnet multipole ion source was designed, fabricated, and demonstrated. Procedures were investigated for texturing a variety of seed and surface materials for controlling secondary electron emission, increasing electron absorption of light, and improved attachment of biological tissue for medical implants using argon and tetrafluoromethane as the working gases. The cross section for argon-argon elastic collisions in the ion-beam energy range was calculated from interaction potentials and permits calculation of beam interaction effects that can determine system pumping requirements. The data also indicate that different optimizations of ion-beam machines will be advantageous for long and short runs, with 1 mA-hr/cm being the rough dividing line for run length. The capacity to simultaneously optimize components in an ion-beam machine for a single application, a capacity that is not evident in competitive approaches such as diode sputtering is emphasized.

First results from the new RIKEN superconducting electron cyclotron resonance ion source (invited).

PubMed

Nakagawa, T; Higurashi, Y; Ohnishi, J; Aihara, T; Tamura, M; Uchiyama, A; Okuno, H; Kusaka, K; Kidera, M; Ikezawa, E; Fujimaki, M; Sato, Y; Watanabe, Y; Komiyama, M; Kase, M; Goto, A; Kamigaito, O; Yano, Y

2010-02-01

The next generation heavy ion accelerator facility, such as the RIKEN radio isotope (RI) beam factory, requires an intense beam of high charged heavy ions. In the past decade, performance of the electron cyclotron resonance (ECR) ion sources has been dramatically improved with increasing the magnetic field and rf frequency to enhance the density and confinement time of plasma. Furthermore, the effects of the key parameters (magnetic field configuration, gas pressure, etc.) on the ECR plasma have been revealed. Such basic studies give us how to optimize the ion source structure. Based on these studies and modern superconducting (SC) technology, we successfully constructed the new 28 GHz SC-ECRIS, which has a flexible magnetic field configuration to enlarge the ECR zone and to optimize the field gradient at ECR point. Using it, we investigated the effect of ECR zone size, magnetic field configuration, and biased disk on the beam intensity of the highly charged heavy ions with 18 GHz microwaves. In this article, we present the structure of the ion source and first experimental results with 18 GHz microwave in detail.

Selective Recovery of Critical Materials from Geothermal Fluid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mayes, Richard T.; Halstenberg, Phillip W.; Moyer, Bruce A.

This project, funded by the DOE Small Business Voucher program, assisted the partner with the development of ion-imprinted adsorbents for the selective extraction of rare earth elements (REE) from geothermal brines. This effort seeks to utilize a currently untapped resource thus diversifying the U. S. REE market. The initial stage of the program focused on the adsorbent developed by partner and optimization of the adsorbent. The adsorbent was based upon an ion imprinted ligand that was copolymerized with a crosslinker to generate the REE selectivity. During this task, the adsorbents were irradiated via electron beam at the NEO Beam Electronmore » Beam Crosslinking Facility (Mercury Plastics, Middlefield, OH) to induce further crosslinking. The irradiation crosslinked adsorbents exhibited no difference in the Fourier transform infrared spectroscopic (FTIR) analysis suggesting inefficiency in the crosslinking. In the later stage of the effort, a new method was proposed and studied at ORNL involving a new partnership between the partner and a commercial polymer vender. This resulted in a new material being developed which allows the partner to utilize a commercial support and integrate the synthesis into a production-ready product stream. This will enhance the route to commercialization for the partner resulting in a quicker market penetration for the product. The new adsorbent exhibits selectivity for REE over transition metals commonly found within geothermal brines. Further optimization is required for enhanced selectivity, capacity, and intra-lanthanide separations.« less

Nanoscale Reactive Ion Etching of Silicon Nitride Thin Films for Embedded Nanomagnetic Device Fabrication

NASA Astrophysics Data System (ADS)

Hibbard-Lubow, David Luke

The demands of digital memory have increased exponentially in recent history, requiring faster, smaller and more accurate storage methods. Two promising solutions to this ever-present problem are Bit Patterned Media (BPM) and Spin-Transfer Torque Magnetic Random Access Memory (STT-MRAM). Producing these technologies requires difficult and expensive fabrication techniques. Thus, the production processes must be optimized to allow these storage methods to compete commercially while continuing to increase their information storage density and reliability. I developed a process for the production of nanomagnetic devices (which can take the form of several types of digital memory) embedded in thin silicon nitride films. My focus was on optimizing the reactive ion etching recipe required to embed the device in the film. Ultimately, I found that recipe 37 (Power: 250W, CF4 nominal/actual flow rate: 25/25.4 sccm, O2 nominal/actual flow rate: 3.1/5.2 sccm, which gave a maximum pressure around 400 mTorr) gave the most repeatable and anisotropic results. I successfully used processes described in this thesis to make embedded nanomagnets, which could be used as bit patterned media. Another promising application of this work is to make embedded magnetic tunneling junctions, which are the storage medium used in MRAM. Doing so will require still some tweaks to the fabrication methods. Techniques for making these changes and their potential effects are discussed.

Optimizing Dense Plasma Focus Neutron Yields With Fast Gas Jets

NASA Astrophysics Data System (ADS)

McMahon, Matthew; Stein, Elizabeth; Higginson, Drew; Kueny, Christopher; Link, Anthony; Schmidt, Andrea

2017-10-01

We report a study using the particle-in-cell code LSP to perform fully kinetic simulations modeling dense plasma focus (DPF) devices with high density gas jets on axis. The high-density jets are modeled in the large-eddy Navier-Stokes code CharlesX, which is suitable for modeling both sub-sonic and supersonic gas flow. The gas pattern, which is essentially static on z-pinch time scales, is imported from CharlesX to LSP for neutron yield predictions. Fast gas puffs allow for more mass on axis while maintaining the optimal pressure for the DPF. As the density of a subsonic jet increases relative to the background fill, we find the neutron yield increases, as does the variability in the neutron yield. Introducing perturbations in the jet density via super-sonic flow (also known as Mach diamonds) allow for consistent seeding of the m =0 instability leading to more consistent ion acceleration and higher neutron yields with less variability. Jets with higher on axis density are found to have the greatest yield. The optimal jet configuration and the necessary jet conditions for increasing neutron yield and reducing yield variability are explored. Simulations of realistic jet profiles are performed and compared to the ideal scenario. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and supported by the Laboratory Directed Research and Development Program (15-ERD-034) at LLNL.

Self-focusing of a high current density ion beam extracted with concave electrodes in a low energy region around 150 eV.

PubMed

Hirano, Y; Kiyama, S; Koguchi, H; Sakakita, H

2014-02-01

Spontaneous self-focusing of ion beam with high current density (Jc ∼ 2 mA/cm(2), Ib ∼ 65 mA) in low energy region (∼150 eV) is observed in a hydrogen ion beam extracted from an ordinary bucket type ion source with three electrodes having concave shape (acceleration, deceleration, and grounded electrodes). The focusing appears abruptly in the beam energy region over ∼135-150 eV, and the Jc jumps up from 0.7 to 2 mA/cm(2). Simultaneously a strong electron flow also appears in the beam region. The electron flow has almost the same current density. Probably these electrons compensate the ion space charge and suppress the beam divergence.

Focused ion beam system

DOEpatents

Leung, Ka-Ngo; Gough, Richard A.; Ji, Qing; Lee, Yung-Hee Yvette

1999-01-01

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 .mu.m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 .mu.m or less.

Focused ion beam system

DOEpatents

Leung, K.; Gough, R.A.; Ji, Q.; Lee, Y.Y.

1999-08-31

A focused ion beam (FIB) system produces a final beam spot size down to 0.1 {mu}m or less and an ion beam output current on the order of microamps. The FIB system increases ion source brightness by properly configuring the first (plasma) and second (extraction) electrodes. The first electrode is configured to have a high aperture diameter to electrode thickness aspect ratio. Additional accelerator and focusing electrodes are used to produce the final beam. As few as five electrodes can be used, providing a very compact FIB system with a length down to only 20 mm. Multibeamlet arrangements with a single ion source can be produced to increase throughput. The FIB system can be used for nanolithography and doping applications for fabrication of semiconductor devices with minimum feature sizes of 0.1 m or less. 13 figs.

WE-FG-BRB-00: The Challenges of Predicting RBE Effects in Particle Therapy and Opportunities for Improving Cancer Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

The physical pattern of energy deposition and the enhanced relative biological effectiveness (RBE) of protons and carbon ions compared to photons offer unique and not fully understood or exploited opportunities to improve the efficacy of radiation therapy. Variations in RBE within a pristine or spread out Bragg peak and between particle types may be exploited to enhance cell killing in target regions without a corresponding increase in damage to normal tissue structures. In addition, the decreased sensitivity of hypoxic tumors to photon-based therapies may be partially overcome through the use of more densely ionizing radiations. These and other differences betweenmore » particle and photon beams may be used to generate biologically optimized treatments that reduce normal tissue complications. In this symposium, speakers will examine the impact of the RBE of charged particles on measurable biological endpoints, treatment plan optimization, and the prediction or retrospective assessment of treatment outcomes. In particular, an AAPM task group was formed to critically examine the evidence for a spatially-variant RBE in proton therapy. Current knowledge of proton RBE variation with respect to dose, biological endpoint, and physics parameters will be reviewed. Further, the clinical relevance of these variations will be discussed. Recent work focused on improving simulations of radiation physics and biological response in proton and carbon ion therapy will also be presented. Finally, relevant biology research and areas of research needs will be highlighted, including the dependence of RBE on genetic factors including status of DNA repair pathways, the sensitivity of cancer stem-like cells to charged particles, the role of charged particles in hypoxic tumors, and the importance of fractionation effects. In addition to the physical advantages of protons and more massive ions over photons, the future application of biologically optimized treatment plans and their potential to provide higher levels of local tumor control and improved normal tissue sparing will be discussed. Learning Objectives: To assess whether the current practice of a constant RBE of 1.1 should be revised or maintained in proton therapy and to evaluate the potential clinical consequences of delivering RBE-weighted dose distributions based on variable RBE To review current research on biological models used to predict the increased biological effectiveness of proton and carbon ions to help move towards a practical understanding and implementation of biological optimization in particle therapy To discuss potential differences in biological mechanisms between photons and charged particles (light and heavy ions) that could impact clinical cancer therapy H. Paganetti, NCI U19 CA21239D. Grosshans, Our research is supported by the NCIK. Held, Funding Support: National Cancer Institute of the National Institutes of Health, USA, under Award Number R21CA182259 and Federal Share of Program Income Earned by Massachusetts General Hospital on C06CA059267, Proton Therapy Research and Treatment Center.« less

WE-FG-BRB-02: Spatial Mapping of the RBE of Scanned Particle Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grosshans, D.

2016-06-15

The physical pattern of energy deposition and the enhanced relative biological effectiveness (RBE) of protons and carbon ions compared to photons offer unique and not fully understood or exploited opportunities to improve the efficacy of radiation therapy. Variations in RBE within a pristine or spread out Bragg peak and between particle types may be exploited to enhance cell killing in target regions without a corresponding increase in damage to normal tissue structures. In addition, the decreased sensitivity of hypoxic tumors to photon-based therapies may be partially overcome through the use of more densely ionizing radiations. These and other differences betweenmore » particle and photon beams may be used to generate biologically optimized treatments that reduce normal tissue complications. In this symposium, speakers will examine the impact of the RBE of charged particles on measurable biological endpoints, treatment plan optimization, and the prediction or retrospective assessment of treatment outcomes. In particular, an AAPM task group was formed to critically examine the evidence for a spatially-variant RBE in proton therapy. Current knowledge of proton RBE variation with respect to dose, biological endpoint, and physics parameters will be reviewed. Further, the clinical relevance of these variations will be discussed. Recent work focused on improving simulations of radiation physics and biological response in proton and carbon ion therapy will also be presented. Finally, relevant biology research and areas of research needs will be highlighted, including the dependence of RBE on genetic factors including status of DNA repair pathways, the sensitivity of cancer stem-like cells to charged particles, the role of charged particles in hypoxic tumors, and the importance of fractionation effects. In addition to the physical advantages of protons and more massive ions over photons, the future application of biologically optimized treatment plans and their potential to provide higher levels of local tumor control and improved normal tissue sparing will be discussed. Learning Objectives: To assess whether the current practice of a constant RBE of 1.1 should be revised or maintained in proton therapy and to evaluate the potential clinical consequences of delivering RBE-weighted dose distributions based on variable RBE To review current research on biological models used to predict the increased biological effectiveness of proton and carbon ions to help move towards a practical understanding and implementation of biological optimization in particle therapy To discuss potential differences in biological mechanisms between photons and charged particles (light and heavy ions) that could impact clinical cancer therapy H. Paganetti, NCI U19 CA21239D. Grosshans, Our research is supported by the NCIK. Held, Funding Support: National Cancer Institute of the National Institutes of Health, USA, under Award Number R21CA182259 and Federal Share of Program Income Earned by Massachusetts General Hospital on C06CA059267, Proton Therapy Research and Treatment Center.« less

WE-FG-BRB-01: Clinical Significance of RBE Variations in Proton Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paganetti, H.

2016-06-15

The physical pattern of energy deposition and the enhanced relative biological effectiveness (RBE) of protons and carbon ions compared to photons offer unique and not fully understood or exploited opportunities to improve the efficacy of radiation therapy. Variations in RBE within a pristine or spread out Bragg peak and between particle types may be exploited to enhance cell killing in target regions without a corresponding increase in damage to normal tissue structures. In addition, the decreased sensitivity of hypoxic tumors to photon-based therapies may be partially overcome through the use of more densely ionizing radiations. These and other differences betweenmore » particle and photon beams may be used to generate biologically optimized treatments that reduce normal tissue complications. In this symposium, speakers will examine the impact of the RBE of charged particles on measurable biological endpoints, treatment plan optimization, and the prediction or retrospective assessment of treatment outcomes. In particular, an AAPM task group was formed to critically examine the evidence for a spatially-variant RBE in proton therapy. Current knowledge of proton RBE variation with respect to dose, biological endpoint, and physics parameters will be reviewed. Further, the clinical relevance of these variations will be discussed. Recent work focused on improving simulations of radiation physics and biological response in proton and carbon ion therapy will also be presented. Finally, relevant biology research and areas of research needs will be highlighted, including the dependence of RBE on genetic factors including status of DNA repair pathways, the sensitivity of cancer stem-like cells to charged particles, the role of charged particles in hypoxic tumors, and the importance of fractionation effects. In addition to the physical advantages of protons and more massive ions over photons, the future application of biologically optimized treatment plans and their potential to provide higher levels of local tumor control and improved normal tissue sparing will be discussed. Learning Objectives: To assess whether the current practice of a constant RBE of 1.1 should be revised or maintained in proton therapy and to evaluate the potential clinical consequences of delivering RBE-weighted dose distributions based on variable RBE To review current research on biological models used to predict the increased biological effectiveness of proton and carbon ions to help move towards a practical understanding and implementation of biological optimization in particle therapy To discuss potential differences in biological mechanisms between photons and charged particles (light and heavy ions) that could impact clinical cancer therapy H. Paganetti, NCI U19 CA21239D. Grosshans, Our research is supported by the NCIK. Held, Funding Support: National Cancer Institute of the National Institutes of Health, USA, under Award Number R21CA182259 and Federal Share of Program Income Earned by Massachusetts General Hospital on C06CA059267, Proton Therapy Research and Treatment Center.« less

A Computer-Based Undergraduate Exercise Using Internet-Accessible Simulation Software for the Study of Retention Behavior and Optimization of Separation Conditions in Ion Chromatography

ERIC Educational Resources Information Center

Haddad, Paul R.; Shaw, Matthew J.; Madden, John E.; Dicinoski, Greg W.

2004-01-01

The ability to scan retention data over a wide range of eluent composition opens up the possibility of a computerized selection of the optimal separation conditions. The major characteristics of retention behavior, peak-shape effects and pH effects evident in ion chromatography (IC) using common stationary phases and eluents are illustrated.

A novel magnetic ion imprinted polymer as a selective magnetic solid phase for separation of trace lead(II) ions from agricultural products, and optimization using a Box-Behnken design.

PubMed

Dahaghin, Zohreh; Mousavi, Hassan Zavvar; Sajjadi, S Maryam

2017-12-15

In this work, a magnetic ion-imprinted polymer (Fe 3 O 4 @SiO 2 @IIP) as a novel and selective nanosorbent for selective extraction of Pb(II) ions from various agricultural products is presented. The novel lead magnetic ion-imprinted polymer was synthesized by imidazole as a new ligand and grafted onto the surface of Fe 3 O 4 @SiO 2 NPs. A Box-Behnken (BBD) design was used for optimization of the extraction and elution steps. In the selected conditions, the limit of detection was 0.48ngmL -1 , preconcentration factor was 300, the sorption capacity of this new magnetic ion-imprinted polymer was 105mgg -1 , and the precision of the method (RSD%) for six replicate measurements was found 3.2%. Finally, the feasibility of the new magnetic ion-imprinted polymer was evaluated by extraction and determination of trace Pb 2+ ions in different agricultural products including (orange, mango, apple, kiwi, lettuce, broccoli, carrot, squash, eggplant, radish, mushroom, cucumber, and tomato). Copyright © 2017 Elsevier Ltd. All rights reserved.

In situ mitigation of subsurface and peripheral focused ion beam damage via simultaneous pulsed laser heating

DOE PAGES

Stanford, Michael G.; Lewis, Brett B.; Iberi, Vighter O.; ...

2016-02-16

Focused helium and neon ion (He(+)/Ne(+) ) beam processing has recently been used to push resolution limits of direct-write nanoscale synthesis. The ubiquitous insertion of focused He(+) /Ne(+) beams as the next-generation nanofabrication tool-of-choice is currently limited by deleterious subsurface and peripheral damage induced by the energetic ions in the underlying substrate. The in situ mitigation of subsurface damage induced by He(+)/Ne(+) ion exposures in silicon via a synchronized infrared pulsed laser-assisted process is demonstrated. The pulsed laser assist provides highly localized in situ photothermal energy which reduces the implantation and defect concentration by greater than 90%. The laser-assisted exposuremore » process is also shown to reduce peripheral defects in He(+) patterned graphene, which makes this process an attractive candidate for direct-write patterning of 2D materials. In conclusion, these results offer a necessary solution for the applicability of high-resolution direct-write nanoscale material processing via focused ion beams.« less

Detection of nitro-based and peroxide-based explosives by fast polarity-switchable ion mobility spectrometer with ion focusing in vicinity of Faraday detector.

PubMed

Zhou, Qinghua; Peng, Liying; Jiang, Dandan; Wang, Xin; Wang, Haiyan; Li, Haiyang

2015-05-29

Ion mobility spectrometer (IMS) has been widely deployed for on-site detection of explosives. The common nitro-based explosives are usually detected by negative IMS while the emerging peroxide-based explosives are better detected by positive IMS. In this study, a fast polarity-switchable IMS was constructed to detect these two explosive species in a single measurement. As the large traditional Faraday detector would cause a trailing reactant ion peak (RIP), a Faraday detector with ion focusing in vicinity was developed by reducing the detector radius to 3.3 mm and increasing the voltage difference between aperture grid and its front guard ring to 591 V, which could remove trailing peaks from RIP without loss of signal intensity. This fast polarity-switchable IMS with ion focusing in vicinity of Faraday detector was employed to detect a mixture of 10 ng 2,4,6-trinitrotoluene (TNT) and 50 ng hexamethylene triperoxide diamine (HMTD) by polarity-switching, and the result suggested that [TNT-H](-) and [HMTD+H](+) could be detected in a single measurement. Furthermore, the removal of trailing peaks from RIP by the Faraday detector with ion focusing in vicinity also promised the accurate identification of KClO4, KNO3 and S in common inorganic explosives, whose product ion peaks were fairly adjacent to RIP.

[Building Mass Spectrometry Spectral Libraries of Human Cancer Cell Lines].

PubMed

Faktor, J; Bouchal, P

Cancer research often focuses on protein quantification in model cancer cell lines and cancer tissues. SWATH (sequential windowed acquisition of all theoretical fragment ion spectra), the state of the art method, enables the quantification of all proteins included in spectral library. Spectral library contains fragmentation patterns of each detectable protein in a sample. Thorough spectral library preparation will improve quantitation of low abundant proteins which usually play an important role in cancer. Our research is focused on the optimization of spectral library preparation aimed at maximizing the number of identified proteins in MCF-7 breast cancer cell line. First, we optimized the sample preparation prior entering the mass spectrometer. We examined the effects of lysis buffer composition, peptide dissolution protocol and the material of sample vial on the number of proteins identified in spectral library. Next, we optimized mass spectrometry (MS) method for spectral library data acquisition. Our thorough optimized protocol for spectral library building enabled the identification of 1,653 proteins (FDR < 1%) in 1 µg of MCF-7 lysate. This work contributed to the enhancement of protein coverage in SWATH digital biobanks which enable quantification of arbitrary protein from physically unavailable samples. In future, high quality spectral libraries could play a key role in preparing of patient proteome digital fingerprints.Key words: biomarker - mass spectrometry - proteomics - digital biobanking - SWATH - protein quantificationThis work was supported by the project MEYS - NPS I - LO1413.The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study.The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers.Submitted: 7. 5. 2016Accepted: 9. 6. 2016.

Preparation and magnetic properties of multiferroic CuMnO2 nanoparticles.

PubMed

Kurokawa, Akinobu; Yanoh, Tkuya; Yano, Shinya; Ichiyanagi, Yuko

2014-03-01

CuMnO2 nanoparticles with diameters of 64 nm were synthesized by a novel wet chemical method. An optimized two-step annealing method was developed through the analysis of thermogravimetric differential thermal analysis (TG-DTA) measurements in order to obtain single-phase CuMnO2. A sharp exothermic peak was observed in the DTA curve at approximately 500 K where structural changes of the copper oxides and manganese oxides in the precursor are expected to occur. It is believed that Cu+ ions were oxidized to Cu2+ ions and that Mn2+ ions were oxidized to Mn3+ ions in the Cu-Mn-O system. Deoxidization reactions were also found at approximately 1200 K. The optimized annealing temperature for the first step was determined to be 623 K in air. The optimized annealing temperature for the second step was 1173 K in an Ar atmosphere. Magnetization measurements suggested an antiferromagnetic spin ordering at approximately 50 K. It was expected that Mn3+ spin interactions induced magnetic phase transition affected by definite temperature.

Initial experiments with a versatile multi-aperture negative-ion source and related improvements

NASA Astrophysics Data System (ADS)

Cavenago, M.

2016-03-01

A relatively compact ion source, named NIO1 (Negative-Ion Optimization 1), with 9 beam apertures for H- extraction is under commissioning, in collaboration between Consorzio RFX and INFN, to provide a test bench for source optimizations, for innovations, and for simulation code validations in support of Neutral Beam Injectors (NBI) optimization. NIO1 installation includes a 60kV high-voltage deck, power supplies for a 130mA ion nominal current, an X-ray shield, and beam diagnostics. Plasma is heated with a tunable 2MHz radiofrequency (rf) generator. Physical aspects of source operation and rf-plasma coupling are discussed. NIO1 tuning procedures and plasma experiments both with air and with hydrogen as filling gas are described, up to a 1.7kW rf power. Transitions to inductively coupled plasma are reported in the case of air (for a rf power of about 0.5kW and a gas pressure below 2Pa), discussing their robust signature in optical emission, and briefly summarized for hydrogen, where more than 1kW rf power is needed.

Application of Chitosan-Zinc Oxide Nanoparticles for Lead Extraction From Water Samples by Combining Ant Colony Optimization with Artificial Neural Network

NASA Astrophysics Data System (ADS)

Khajeh, M.; Pourkarami, A.; Arefnejad, E.; Bohlooli, M.; Khatibi, A.; Ghaffari-Moghaddam, M.; Zareian-Jahromi, S.

2017-09-01

Chitosan-zinc oxide nanoparticles (CZPs) were developed for solid-phase extraction. Combined artificial neural network-ant colony optimization (ANN-ACO) was used for the simultaneous preconcentration and determination of lead (Pb2+) ions in water samples prior to graphite furnace atomic absorption spectrometry (GF AAS). The solution pH, mass of adsorbent CZPs, amount of 1-(2-pyridylazo)-2-naphthol (PAN), which was used as a complexing agent, eluent volume, eluent concentration, and flow rates of sample and eluent were used as input parameters of the ANN model, and the percentage of extracted Pb2+ ions was used as the output variable of the model. A multilayer perception network with a back-propagation learning algorithm was used to fit the experimental data. The optimum conditions were obtained based on the ACO. Under the optimized conditions, the limit of detection for Pb2+ ions was found to be 0.078 μg/L. This procedure was also successfully used to determine the amounts of Pb2+ ions in various natural water samples.

Numerical analysis of ion wind flow using space charge for optimal design

NASA Astrophysics Data System (ADS)

Ko, Han Seo; Shin, Dong Ho; Baek, Soo Hong

2014-11-01

Ion wind flow has been widly studied for its advantages of a micro fluidic device. However, it is very difficult to predict the performance of the ion wind flow for various conditions because of its complicated electrohydrodynamic phenomena. Thus, a reliable numerical modeling is required to design an otimal ion wind generator and calculate velocity of the ion wind for the proper performance. In this study, the numerical modeling of the ion wind has been modified and newly defined to calculate the veloctiy of the ion wind flow by combining three basic models such as electrostatics, electrodynamics and fluid dynamics. The model has included presence of initial space charges to calculate transfer energy between space charges and air gas molecules using a developed space charge correlation. The simulation has been performed for a geometry of a pin to parallel plate electrode. Finally, the results of the simulation have been compared with the experimental data for the ion wind velocity to confirm the accuracy of the modified numerical modeling and to obtain the optimal design of the ion wind generator. This work was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Korean government (MEST) (No. 2013R1A2A2A01068653).

Experimental Validation of an Ion Beam Optics Code with a Visualized Ion Thruster

NASA Astrophysics Data System (ADS)

Nakayama, Yoshinori; Nakano, Masakatsu

For validation of an ion beam optics code, the behavior of ion beam optics was experimentally observed and evaluated with a two-dimensional visualized ion thruster (VIT). Since the observed beam focus positions, sheath positions and measured ion beam currents were in good agreement with the numerical results, it was confirmed that the numerical model of this code was appropriated. In addition, it was also confirmed that the beam focus position was moved on center axis of grid hole according to the applied grid potentials, which differs from conventional understanding/assumption. The VIT operations may be useful not only for the validation of ion beam optics codes but also for the fundamental and intuitive understanding of the Child Law Sheath theory.

Material exposure effects in a simulated low-Earth orbit environment

NASA Astrophysics Data System (ADS)

Maldonado, C.; McHarg, G.; Asmolova, O.; Andersen, G.; Rodrigues, S.; Ketsdever, A.

2016-11-01

Spacecraft operating in low-Earth orbit (LEO) are subjected to a number of hazardous environmental constituents that can lead to decreased system performance and reduced operational lifetimes. Due to their thermal, optical, and mechanical properties, polymers are used extensively in space systems; however they are particularly susceptible to material erosion and degradation as a result of exposure to the LEO environment. The focus of this research is to examine the material erosion and mass loss experienced by the Novastrat 500 polyimide due to exposure in a simulated LEO environment. In addition to the polymer samples, chrome, silver and gold specimens will be examined to measure the oxidation rate and act as a control specimen, respectively. A magnetically filtered atomic oxygen plasma source has previously been developed and characterized for the purpose of simulating the low-Earth orbit environment. The plasma source can be operated at a variety of discharge currents and gas flow rates, of which the plasma parameters downstream of the source are dependent. The characteristics of the generated plasma were examined as a function of these operating parameters to optimize the production of O+ ions with energy relevant to LEO applications, where the ram energy of the ions due to the motion of the satellite relative to the LEO plasma is high (e.g. 7800 m/s, which corresponds to approximately 5 eV of kinetic energy for O+ ions). The plasma downstream of the source consists of streaming ions with energy of approximately 5 eV and an ion species fraction that is approximately 90% O+.

Rational design and optimization of downstream processes of virus particles for biopharmaceutical applications: current advances.

PubMed

Vicente, Tiago; Mota, José P B; Peixoto, Cristina; Alves, Paula M; Carrondo, Manuel J T

2011-01-01

The advent of advanced therapies in the pharmaceutical industry has moved the spotlight into virus-like particles and viral vectors produced in cell culture holding great promise in a myriad of clinical targets, including cancer prophylaxis and treatment. Even though a couple of cases have reached the clinic, these products have yet to overcome a number of biological and technological challenges before broad utilization. Concerning the manufacturing processes, there is significant research focusing on the optimization of current cell culture systems and, more recently, on developing scalable downstream processes to generate material for pre-clinical and clinical trials. We review the current options for downstream processing of these complex biopharmaceuticals and underline current advances on knowledge-based toolboxes proposed for rational optimization of their processing. Rational tools developed to increase the yet scarce knowledge on the purification processes of complex biologicals are discussed as alternative to empirical, "black-boxed" based strategies classically used for process development. Innovative methodologies based on surface plasmon resonance, dynamic light scattering, scale-down high-throughput screening and mathematical modeling for supporting ion-exchange chromatography show great potential for a more efficient and cost-effective process design, optimization and equipment prototyping. Copyright © 2011 Elsevier Inc. All rights reserved.

Focused Ion Beam Fabrication of Graded Channel Field Effect Transistors (FETs) in GaAs and Si

DTIC Science & Technology

1988-11-21

is used even though the cut may need to be - I-am wide. Since theL ± ne REMOVAL etch time varies as the inverse square of the beam diameter , a ROF...at room temperature a fairly large diameter capillary 1.4-mm and ion induced deposition or etching , the focused ion beam inner diameter was used . For...Pd/B/As/P (alloy sources) Main - micromachining - implantation uses - ion induced deposition - lithography and etching - high resolution SIMS

Modularized battery management for large lithium ion cells

NASA Astrophysics Data System (ADS)

Stuart, Thomas A.; Zhu, Wei

A modular electronic battery management system (BMS) is described along with important features for protecting and optimizing the performance of large lithium ion (LiIon) battery packs. Of particular interest is the use of a much improved cell equalization system that can increase or decrease individual cell voltages. Experimental results are included for a pack of six series connected 60 Ah (amp-hour) LiIon cells.

Optimal N:P ratios of growth media: quantification of nutrient-replete growth rates in five ion hyperspace for Chlorella vulgaris (Dinophyceae) and Peridinium cinctum (Dinophyceae).

USDA-ARS?s Scientific Manuscript database

In this study our principal goal was to quantify the main effects and interactions of several primary nutrient and bulk solution ions. The total ion concentration range chosen spans fresh to brackish waters (1-30 milliMolar) and explores most of the hypervolume delineated by the five ion/concentrat...

ION PULSE GENERATION

DOEpatents

King, R.F.; Moak, C.D.; Parker, V.E.

1960-10-11

A device for generating ions in an ion source, forming the ions into a stream, deflecting the stream rapidly away from and back to its normal path along the axis of a cylindrical housing, and continually focusing the stream by suitable means into a sharp, intermittent beam along the axis is described. The beam exists through an axial aperture into a lens which focuses it into an accelerator tube. The ions in each burst are there accelerated to very high energies and are directed against a target placed in the high-energy end of the tube. Radiations from the target can then be analyzed in the interval between incidence of the bursts of ions on the target.

Coulomb interaction rules timescales in potassium ion channel tunneling

NASA Astrophysics Data System (ADS)

De March, N.; Prado, S. D.; Brunnet, L. G.

2018-06-01

Assuming the selectivity filter of KcsA potassium ion channel may exhibit quantum coherence, we extend a previous model by Vaziri and Plenio (2010 New J. Phys. 12 085001) to take into account Coulomb repulsion between potassium ions. We show that typical ion transit timescales are determined by this interaction, which imposes optimal input/output parameter ranges. Also, as observed in other examples of quantum tunneling in biological systems, the addition of moderate noise helps coherent ion transport.

Thermally assisted infrared multiphoton photodissociation in a quadrupole ion trap.

PubMed

Payne, A H; Glish, G L

2001-08-01

Thermally assisted infrared multiphoton photodissociation (TA-IRMPD) provides an effective means to dissociate ions in the quadrupole ion trap mass spectrometer (QITMS) without detrimentally affecting the performance of the instrument. IRMPD can offer advantages over collision-induced dissociation (CID). However, collisions with the QITMS bath gas at the standard pressure and ambient temperature cause IR-irradiated ions to lose energy faster than photons can be absorbed to induce dissociation. The low pressure required for IRMPD (< or = 10(-5) Torr) is not that required for optimal performance of the QITMS (10(-3) Torr), and sensitivity and resolution suffer. TA-IRMPD is performed with the bath gas at an elevated temperature. The higher temperature of the bath gas results in less energy lost in collisions of the IR-excited ions with the bath gas. Thermal assistance allows IRMPD to be used at or near optimal pressures, which results in an approximately 1 order of magnitude increase in signal intensity. Unlike CID, IRMPD allows small product ions, those less than about one-third the m/z of the parent ion, to be observed. IRMPD should also be more easily paired with fluctuating ion sources, as the corresponding fluctuations in resonant frequencies do not affect IRMPD. Finally, while IR irradiation nonselectively causes dissociation of all ions, TA-IRMPD can be made selective by using axial expansion to move ions away from the path of the laser beam.

Correlation between y-type ions observed in ion trap and triple quadrupole mass spectrometers.

PubMed

Sherwood, Carly A; Eastham, Ashley; Lee, Lik Wee; Risler, Jenni; Vitek, Olga; Martin, Daniel B

2009-09-01

Multiple reaction monitoring mass spectrometry (MRM-MS) is a technique for high-sensitivity targeted analysis. In proteomics, MRM-MS can be used to monitor and quantify a peptide based on the production of expected fragment peaks from the selected peptide precursor ion. The choice of which fragment ions to monitor in order to achieve maximum sensitivity in MRM-MS can potentially be guided by existing MS/MS spectra. However, because the majority of discovery experiments are performed on ion trap platforms, there is concern in the field regarding the generalizability of these spectra to MRM-MS on a triple quadrupole instrument. In light of this concern, many operators perform an optimization step to determine the most intense fragments for a target peptide on a triple quadrupole mass spectrometer. We have addressed this issue by targeting, on a triple quadrupole, the top six y-ion peaks from ion trap-derived consensus library spectra for 258 doubly charged peptides from three different sample sets and quantifying the observed elution curves. This analysis revealed a strong correlation between the y-ion peak rank order and relative intensity across platforms. This suggests that y-type ions obtained from ion trap-based library spectra are well-suited for generating MRM-MS assays for triple quadrupoles and that optimization is not required for each target peptide.

Pharmaceutical Applications of Ion-Exchange Resins

NASA Astrophysics Data System (ADS)

Elder, David P.

2005-04-01

The historical uses of ion-exchange resins and a summary of the basic chemical principles involved in the ion-exchange process are discussed. Specific applications of ion-exchange resins are provided. The utility of these agents to stabilize drugs are evaluated. Commonly occurring chemical and physical incompatibilities are reviewed. Ion-exchange resins have found applicability as inactive pharmaceutical constituents, particularly as disintegrants (inactive tablet ingredient whose function is to rapidly disrupt the tablet matrix on contact with gastric fluid). One of the more elegant approaches to improving palatability of ionizable drugs is the use of ion-exchange resins as taste-masking agents. The selection, optimization of drug:resin ratio and particle size, together with a review of scaleup of typical manufacturing processes for taste-masked products are provided. Ion-exchange resins have been extensively utilized in oral sustained-release products. The selection, optimization of drug:resin ratio and particle size, together with a summary of commonly occurring commercial sustained-release products are discussed. Ion-exchange resins have also been used in topical products for local application to the skin, including those where drug flux is controlled by a differential electrical current (ionotophoretic delivery). General applicability of ion-exchange resins, including ophthalmic delivery, nasal delivery, use as drugs in their own right (e.g., colestyramine, formerly referred to as cholestyramine), as well as measuring gastrointestinal transit times, are discussed. Finally, pharmaceutical monographs for ion-exchange resins are reviewed.

Ion Beam Measurements of a Dense Plasma Focus Device Using CR 39 Nuclear Track Detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ngoi, S. K.; Yap, S. L.; Wong, C. S.

The project is carried out using a small Mather type plasma focus device powered by a 15 kV, 30 {mu}F capacitor. The filling gas used is argon. The ion beam generated is investigated by both time resolved and time integrated methods. Investigation on the dynamic of the current sheath is also carried out in order to obtain an optimum condition for ion beam production. The angular distribution of the ion emission is measured at positions of 0 deg. (end-on), 45 deg. and 90 deg. (side-on) by using CR-39 nuclear track detectors. The divergence of the ion beam is also determinedmore » using these detectors. A biased ion collector is used for time resolved measurement of the ion beam. Time of flight technique is employed for the determination of the ion beam energy. Average ion beam energy obtained is about 180 keV. The ion beam produced can be used for applications such as material surface modification and ion implantation.« less

Optimization of solenoid based low energy beam transport line for high current H+ beams

NASA Astrophysics Data System (ADS)

Pande, R.; Singh, P.; Rao, S. V. L. S.; Roy, S.; Krishnagopal, S.

2015-02-01

A 20 MeV, 30 mA CW proton linac is being developed at BARC, Mumbai. This linac will consist of an ECR ion source followed by a Radio Frequency Quadrupole (RFQ) and Drift tube Linac (DTL). The low energy beam transport (LEBT) line is used to match the beam from the ion source to the RFQ with minimum beam loss and increase in emittance. The LEBT is also used to eliminate the unwanted ions like H2+ and H3+ from entering the RFQ. In addition, space charge compensation is required for transportation of such high beam currents. All this requires careful design and optimization. Detailed beam dynamics simulations have been done to optimize the design of the LEBT using the Particle-in-cell code TRACEWIN. We find that with careful optimization it is possible to transport a 30 mA CW proton beam through the LEBT with 100% transmission and minimal emittance blow up, while at the same time suppressing unwanted species H2+ and H3+ to less than 3.3% of the total beam current.

Optimization of parameters affecting signal intensity in an LTQ-orbitrap in negative ion mode: A design of experiments approach.

PubMed

Lemonakis, Nikolaos; Skaltsounis, Alexios-Leandros; Tsarbopoulos, Anthony; Gikas, Evagelos

2016-01-15

A multistage optimization of all the parameters affecting detection/response in an LTQ-orbitrap analyzer was performed, using a design of experiments methodology. The signal intensity, a critical issue for mass analysis, was investigated and the optimization process was completed in three successive steps, taking into account the three main regions of an orbitrap, the ion generation, the ion transmission and the ion detection regions. Oleuropein and hydroxytyrosol were selected as the model compounds. Overall, applying this methodology the sensitivity was increased more than 24%, the resolution more than 6.5%, whereas the elapsed scan time was reduced nearly to its half. A high-resolution LTQ Orbitrap Discovery mass spectrometer was used for the determination of the analytes of interest. Thus, oleuropein and hydroxytyrosol were infused via the instruments syringe pump and they were analyzed employing electrospray ionization (ESI) in the negative high-resolution full-scan ion mode. The parameters of the three main regions of the LTQ-orbitrap were independently optimized in terms of maximum sensitivity. In this context, factorial design, response surface model and Plackett-Burman experiments were performed and analysis of variance was carried out to evaluate the validity of the statistical model and to determine the most significant parameters for signal intensity. The optimum MS conditions for each analyte were summarized and the method optimum condition was achieved by maximizing the desirability function. Our observation showed good agreement between the predicted optimum response and the responses collected at the predicted optimum conditions. Copyright © 2015 Elsevier B.V. All rights reserved.

Prize for Industrial Applications of Physics Talk: Low energy spread Ion source for focused ion beam systems-Search for the holy grail

NASA Astrophysics Data System (ADS)

Ward, Bill

2011-03-01

In this talk I will cover my personal experiences as a serial entrepreneur and founder of a succession of focused ion beam companies (1). Ion Beam Technology, which developed a 200kv (FIB) direct ion implanter (2). Micrion, where the FIB found a market in circuit edit and mask repair, which eventually merged with FEI corporation. and (3). ALIS Corporation which develop the Orion system, the first commercially successful sub-nanometer helium ion microscope, that was ultimately acquired by Carl Zeiss corporation. I will share this adventure beginning with my experiences in the early days of ion beam implantation and e-beam lithography which lead up to the final breakthrough understanding of the mechanisms that govern the successful creation and operation of a single atom ion source.

Development of a linear-type double reflectron for focused imaging of photofragment ions from mass-selected complex ions

NASA Astrophysics Data System (ADS)

Okutsu, Kenichi; Nakashima, Yuji; Yamazaki, Kenichiro; Fujimoto, Keita; Nakano, Motoyoshi; Ohshimo, Keijiro; Misaizu, Fuminori

2017-05-01

An ion imaging apparatus with a double linear reflectron mass spectrometer has been developed, in order to measure velocity and angular distributions of mass-analyzed fragment ions produced by photodissociation of mass-selected gas phase complex ions. The 1st and the 2nd linear reflectrons were placed facing each other and controlled by high-voltage pulses in order to perform the mass-separation of precursor ions in the 1st reflectron and to observe the focused image of the photofragment ions in the 2nd reflectron. For this purpose, metal meshes were attached on all electrodes in the 1st reflectron, whereas the mesh was attached only on the last electrode in the 2nd reflectron. The performance of this apparatus was evaluated using imaging measurement of Ca+ photofragment ions from photodissociation reaction of Ca+Ar complex ions at 355 nm photoexcitation. The focused ion images were obtained experimentally with the double linear reflectron at the voltages of the reflection electrodes close to the predictions by ion trajectory simulations. The velocity and angular distributions of the produced Ca+ ([Ar] 4p1, 2P3/2) ion were analyzed from the observed images. The binding energy D0 of Ca+Ar in the ground state deduced in the present measurement was consistent with those determined theoretically and by spectroscopic measurements. The anisotropy parameter β of the transition was evaluated for the first time by this instrument.

Ion Emittance Growth Due to Focusing Modulation from Slipping Electron Bunch

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, G.

2015-02-17

Low energy RHIC operation has to be operated at an energy ranging from γ = 4.1 to γ = 10. The energy variation causes the change of revolution frequency. While the rf system for the circulating ion will operate at an exact harmonic of the revolution frequency (h=60 for 4.5 MHz rf and h=360 for 28 MHz rf.), the superconducting rf system for the cooling electron beam does not have a frequency tuning range that is wide enough to cover the required changes of revolution frequency. As a result, electron bunches will sit at different locations along the ion bunchmore » from turn to turn, i.e. the slipping of the electron bunch with respect to the circulating ion bunch. At cooling section, ions see a coherent focusing force due to the electrons’ space charge, which differs from turn to turn due to the slipping. We will try to estimate how this irregular focusing affects the transverse emittance of the ion bunch.« less

High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region.

PubMed

Hirano, Y; Kiyama, S; Fujiwara, Y; Koguchi, H; Sakakita, H

2015-11-01

A high current density (≈3 mA/cm(2)) hydrogen ion beam source operating in an extremely low-energy region (E(ib) ≈ 150-200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E(ib) is being reduced. The radial profiles of the ion beam current density and the low temperature ion current density can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.

Picosecond laser micromachining prior to FIB milling for electronic microscopy sample preparation

NASA Astrophysics Data System (ADS)

Sikora, Aurélien; Fares, Lahouari; Adrian, Jérôme; Goubier, Vincent; Delobbe, Anne; Corbin, Antoine; Sentis, Marc; Sarnet, Thierry

2017-10-01

In order to check the manufacturing quality of electronic components using electron microscopy, the area of interest must be exposed. This requires the removal of a large quantity of matter without damaging the surrounding area. This step can be accomplished using ion milling but the processing can last a few hours. In order to accelerate the preparation of the samples, picosecond laser micromachining prior to Focused Ion Beam polishing is envisioned. Laser ablation allows the fast removal of matter but induces damages around the ablated area. Therefore the process has to be optimized in order to limit the size of both the heat affected zone and induced dislocation zone. For this purpose, cavities have been engraved in silicon and in electronic components, using a linearly polarized picosecond laser (∼50 ps) at three different wavelengths (343, 515 and 1030 nm). Results showed that the cross sectional shapes and the surface topologies can be tuned by the laser fluence and the number of pulses. Clear cross sections of bumps and cavity openings, exposing multilayer interfaces, are demonstrated. The silicon removal rates, tuned by the applied energy density, have been measured. Removal rates achieved at 200 kHz were typically hundred times higher than those achieved by ion milling and the best efficiency was obtained at 343 nm.

Electron cyclotron resonance sources: Historical review and future prospects (invited)

NASA Astrophysics Data System (ADS)

Geller, R.

1998-03-01

Low charge state electron cyclotron resonance ion source (ECRIS) work since 1965 and high charge state ECRIS since 1974. These ECR sources are categorized into three main sections: (1) Low charged ion (ECRIS) inside simple magnetic mirror or Bucket configurations. (2) High charged ion ECRIS inside min-B mirror configurations. (3) Short pulsed ECRIS with highly charged ions where the ion confinement is disturbed for a short while, which allows the extraction of intense ion pulses. Future prospects are based on rational scaling of the magnetic confinement including high B modes, by increasing the radio frequency (rf) frequency and ECR magnetic field. In this case, charge exchange has to be minimized and plasma instabilities have to be avoided. However, clever empirical tricks lead also to outstanding not always predicted improvements. Let us cite: optimized rf plasma coupling, electron guns, gas mixing, wall coating, biased electrodes, and more recently multiple ECR frequency heating. ECRIS have not yet achieved their optimal possibilities. Let us wait for the next generation of superconducting ECRIS and the possible use of subcentimeter waves.

Electron cyclotron resonance sources: Historical review and future prospects (invited)

NASA Astrophysics Data System (ADS)

Geller, R.

1998-02-01

Low charge state electron cyclotron resonance ion source (ECRIS) work since 1965 and high charge state ECRIS since 1974. These ECR sources are categorized into three main sections: (1) Low charged ion (ECRIS) inside simple magnetic mirror or Bucket configurations. (2) High charged ion ECRIS inside min-B mirror configurations. (3) Short pulsed ECRIS with highly charged ions where the ion confinement is disturbed for a short while, which allows the extraction of intense ion pulses. Future prospects are based on rational scaling of the magnetic confinement including high B modes, by increasing the radio frequency (rf) frequency and ECR magnetic field. In this case, charge exchange has to be minimized and plasma instabilities have to be avoided. However, clever empirical tricks lead also to outstanding not always predicted improvements. Let us cite: optimized rf plasma coupling, electron guns, gas mixing, wall coating, biased electrodes, and more recently multiple ECR frequency heating. ECRIS have not yet achieved their optimal possibilities. Let us wait for the next generation of superconducting ECRIS and the possible use of subcentimeter waves.

Universal main magnetic focus ion source for production of highly charged ions

NASA Astrophysics Data System (ADS)

Ovsyannikov, V. P.; Nefiodov, A. V.; Levin, A. A.

2017-10-01

A novel room-temperature compact ion source has been developed for the efficient production of atomic ions by means of an electron beam with energy Ee and current density je controllable within wide ranges (100 eV ≲Ee ≲ 60 keV, 10 A/cm2 ≲je ≲ 20 kA/cm2). In the first experiments, the X-ray emission of Ir64+ ions has been measured. Based on a combination of two different techniques, the device can operate both as conventional Electron Beam Ion Source/Trap and novel Main Magnetic Focus Ion Source. The tunable electron-optical system allows for realizing laminar and turbulent electron flows in a single experimental setup. The device is intended primarily for fundamental and applied research at standard university laboratories.

Techniques for optimizing nanotips derived from frozen taylor cones

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirsch, Gregory

Optimization techniques are disclosed for producing sharp and stable tips/nanotips relying on liquid Taylor cones created from electrically conductive materials with high melting points. A wire substrate of such a material with a preform end in the shape of a regular or concave cone, is first melted with a focused laser beam. Under the influence of a high positive potential, a Taylor cone in a liquid/molten state is formed at that end. The cone is then quenched upon cessation of the laser power, thus freezing the Taylor cone. The tip of the frozen Taylor cone is reheated by the lasermore » to allow its precise localized melting and shaping. Tips thus obtained yield desirable end-forms suitable as electron field emission sources for a variety of applications. In-situ regeneration of the tip is readily accomplished. These tips can also be employed as regenerable bright ion sources using field ionization/desorption of introduced chemical species.« less

Competition among Li+, Na+, K+ and Rb+ Monovalent Ions for DNA in Molecular Dynamics Simulations using the Additive CHARMM36 and Drude Polarizable Force Fields

PubMed Central

Savelyev, Alexey; MacKerell, Alexander D.

2015-01-01

In the present study we report on interactions of and competition between monovalent ions for two DNA sequences in MD simulations. Efforts included the development and validation of parameters for interactions among the first-group monovalent cations, Li+, Na+, K+ and Rb+, and DNA in the Drude polarizable and additive CHARMM36 force fields (FF). The optimization process targeted gas-phase QM interaction energies of various model compounds with ions and osmotic pressures of bulk electrolyte solutions of chemically relevant ions. The optimized ionic parameters are validated against counterion condensation theory and buffer exchange-atomic emission spectroscopy measurements providing quantitative data on the competitive association of different monovalent ions with DNA. Comparison between experimental and MD simulation results demonstrates that, compared to the additive CHARMM36 model, the Drude FF provides an improved description of the general features of the ionic atmosphere around DNA and leads to closer agreement with experiment on the ionic competition within the ion atmosphere. Results indicate the importance of extended simulation systems on the order of 25 Å beyond the DNA surface to obtain proper convergence of ion distributions. PMID:25751286

New insight into adsorption characteristics and mechanisms of the biosorbent from waste activated sludge for heavy metals.

PubMed

Zhou, Yun; Zhang, Zhiqiang; Zhang, Jiao; Xia, Siqing

2016-07-01

The adsorption characteristics and mechanisms of the biosorbent from waste activated sludge were investigated by adsorbing Pb(2+) and Zn(2+) in aqueous single-metal solutions. A pH value of the metal solutions at 6.0 was beneficial to the high adsorption quantity of the biosorbent. The optimal mass ratio of the biosorbent to metal ions was found to be 2. A higher adsorption quantity of the biosorbent was achieved by keeping the reaction temperature below 55°C. Response surface methodology was applied to optimize the biosorption processes, and the developed mathematical equations showed high determination coefficients (above 0.99 for both metal ions) and insignificant lack of fit (p=0.0838 and 0.0782 for Pb(2+) and Zn(2+), respectively). Atomic force microscopy analyses suggested that the metal elements were adsorbed onto the biosorbent surface via electrostatic interaction. X-ray photoelectron spectroscopy analyses indicated the presence of complexation (between -NH2, -CN and metal ions) and ion-exchange (between -COOH and metal ions). The adsorption mechanisms could be the combined action of electrostatic interaction, complexation and ion-exchange between functional groups and metal ions. Copyright © 2016. Published by Elsevier B.V.

Ion collector design for an energy recovery test proposal with the negative ion source NIO1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Variale, V., E-mail: vincenzo.variale@ba.infn.it; Cavenago, M.; Agostinetti, P.

2016-02-15

Commercial viability of thermonuclear fusion power plants depends also on minimizing the recirculation power used to operate the reactor. The neutral beam injector (NBI) remains one of the most important method for plasma heating and control. For the future fusion power plant project DEMO, a NBI wall plug efficiency at least of 0.45 is required, while efficiency of present NBI project is about 0.25. The D{sup −} beam from a negative ion source is partially neutralized by a gas cell, which leaves more than 40% of energy in residual beams (D{sup −} and D{sup +}), so that an ion beammore » energy recovery system can significantly contribute to optimize efficiency. Recently, the test negative ion source NIO1 (60 keV, 9 beamlets with 15 mA H{sup −} each) has been designed and built at RFX (Padua) for negative ion production efficiency and the beam quality optimization. In this paper, a study proposal to use the NIO1 source also for a beam energy recovery test experiment is presented and a preliminary design of a negative ion beam collector with simulations of beam energy recovery is discussed.« less

Micro/nanofabrication of poly({sub L}-lactic acid) using focused ion beam direct etching

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oyama, Tomoko Gowa; Nagasawa, Naotsugu; Taguchi, Mitsumasa

2013-10-14

Micro/nanofabrication of biocompatible and biodegradable poly({sub L}-lactic acid) (PLLA) using focused Ga ion beam direct etching was evaluated for future bio-device applications. The fabrication performance was determined with different ion fluences and fluxes (beam currents), and it was found that the etching speed and fabrication accuracy were affected by irradiation-induced heat. Focused ion beam (FIB)-irradiated surfaces were analyzed using micro-area X-ray photoelectron spectroscopy. Owing to reactions such as the physical sputtering of atoms and radiation-induced decomposition, PLLA was gradually carbonized with increasing C=C bonds. Controlled micro/nanostructures of PLLA were fabricated with C=C bond-rich surfaces expected to have good cell attachmentmore » properties.« less

Computational multiobjective topology optimization of silicon anode structures for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Mitchell, Sarah L.; Ortiz, Michael

2016-09-01

This study utilizes computational topology optimization methods for the systematic design of optimal multifunctional silicon anode structures for lithium-ion batteries. In order to develop next generation high performance lithium-ion batteries, key design challenges relating to the silicon anode structure must be addressed, namely the lithiation-induced mechanical degradation and the low intrinsic electrical conductivity of silicon. As such this work considers two design objectives, the first being minimum compliance under design dependent volume expansion, and the second maximum electrical conduction through the structure, both of which are subject to a constraint on material volume. Density-based topology optimization methods are employed in conjunction with regularization techniques, a continuation scheme, and mathematical programming methods. The objectives are first considered individually, during which the influence of the minimum structural feature size and prescribed volume fraction are investigated. The methodology is subsequently extended to a bi-objective formulation to simultaneously address both the structural and conduction design criteria. The weighted sum method is used to derive the Pareto fronts, which demonstrate a clear trade-off between the competing design objectives. A rigid frame structure was found to be an excellent compromise between the structural and conduction design criteria, providing both the required structural rigidity and direct conduction pathways. The developments and results presented in this work provide a foundation for the informed design and development of silicon anode structures for high performance lithium-ion batteries.

Targeting high value metals in lithium-ion battery recycling via shredding and size-based separation.

PubMed

Wang, Xue; Gaustad, Gabrielle; Babbitt, Callie W

2016-05-01

Development of lithium-ion battery recycling systems is a current focus of much research; however, significant research remains to optimize the process. One key area not studied is the utilization of mechanical pre-recycling steps to improve overall yield. This work proposes a pre-recycling process, including mechanical shredding and size-based sorting steps, with the goal of potential future scale-up to the industrial level. This pre-recycling process aims to achieve material segregation with a focus on the metallic portion and provide clear targets for subsequent recycling processes. The results show that contained metallic materials can be segregated into different size fractions at different levels. For example, for lithium cobalt oxide batteries, cobalt content has been improved from 35% by weight in the metallic portion before this pre-recycling process to 82% in the ultrafine (<0.5mm) fraction and to 68% in the fine (0.5-1mm) fraction, and been excluded in the larger pieces (>6mm). However, size fractions across multiple battery chemistries showed significant variability in material concentration. This finding indicates that sorting by cathode before pre-treatment could reduce the uncertainty of input materials and therefore improve the purity of output streams. Thus, battery labeling systems may be an important step towards implementation of any pre-recycling process. Copyright © 2015 Elsevier Ltd. All rights reserved.

Back-streaming ion emission and beam focusing on high power linear induction accelerator

NASA Astrophysics Data System (ADS)

Zhu, Jun; Chen, Nan; Yu, Haijun; Jiang, Xiaoguo; Wang, Yuan; Dai, Wenhua; Gao, Feng; Wang, Minhong; Li, Jin; Shi, Jinshui

2011-08-01

Ions released from target surfaces by impact of a high intensity and current electron beam can be accelerated and trapped in the beam potential, and further destroy the beam focus. By solving the 2D Poisson equation, we found that the charge neutralization factor of the ions to the beam under space charge limited condition is 1/3, which is large enough to disrupt the spot size. Therefore, the ion emission at the target in a single-pulse beam/target system must be source limited. Experimental results on the time-resolved beam profile measurement have also proven that. A new focus scheme is proposed in this paper to focus the beam to a small spot size with the existence of back-streaming ions. We found that the focal spot will move upstream as the charge neutralization factor increases. By comparing the theoretical and experimental focal length of the Dragon-I accelerator (20 MeV, 2.5 kA, 60 ns flattop), we found that the average neutralization factor is about 5% in the beam/target system.

Enhanced ion acceleration in transition from opaque to transparent plasmas

NASA Astrophysics Data System (ADS)

Mishra, R.; Fiuza, F.; Glenzer, S.

2018-04-01

Using particle-in-cell simulations, we investigate ion acceleration in the interaction of high intensity lasers with plasmas which transition from opaque to transparent during the interaction process. We show that the highest ion energies are achieved when the laser traverses the target around the peak intensity and re-heats the electron population responsible for the plasma expansion, enhancing the corresponding sheath electric field. This process can lead to an increase of up to 2x in ion energy when compared with the standard Target Normal Sheath Acceleration in opaque targets under the same laser conditions. A theoretical model is developed to predict the optimal target areal density as a function of laser intensity and pulse duration. A systematic parametric scan for a wide range of target densities and thicknesses is performed in 1D, 2D and 3D and shown consistent with the theory and with recent experimental results. These results open the way for a better optimization of the ion energy in future laser–solid experiments.

Efficient Raman sideband cooling of trapped ions to their motional ground state

NASA Astrophysics Data System (ADS)

Che, H.; Deng, K.; Xu, Z. T.; Yuan, W. H.; Zhang, J.; Lu, Z. H.

2017-07-01

Efficient cooling of trapped ions is a prerequisite for various applications of the ions in precision spectroscopy, quantum information, and coherence control. Raman sideband cooling is an effective method to cool the ions to their motional ground state. We investigate both numerically and experimentally the optimization of Raman sideband cooling strategies and propose an efficient one, which can simplify the experimental setup as well as reduce the number of cooling pulses. Several cooling schemes are tested and compared through numerical simulations. The simulation result shows that the fixed-width pulses and varied-width pulses have almost the same efficiency for both the first-order and the second-order Raman sideband cooling. The optimized strategy is verified experimentally. A single 25Mg+ ion is trapped in a linear Paul trap and Raman sideband cooled, and the achieved average vibrational quantum numbers under different cooling strategies are evaluated. A good agreement between the experimental result and the simulation result is obtained.

Surface production dominating Cs-free H- ion source for high intensity and high energy proton accelerators

NASA Astrophysics Data System (ADS)

Ueno, Akira; Ikegami, Kiyoshi; Kondo, Yasuhiro

2004-05-01

A Cs-free negative hydrogen (H-) ion source driven by pulsed arc plasma with a LaB6 filament is being operated for the beam tests of the Japan Proton Accelerator Research Complex (J-PARC) linac. A peak H- current of 38 mA, which exceeds the requirement of the J-PARC first stage, is stably extracted from the ion source with a beam duty factor of 0.9% (360 μs×25 Hz) by principally optimizing the surface condition and shape of the plasma electrode. The sufficiently small emittance of the beam was confirmed by high transmission efficiency (around 90%) through the following 324 MHz 3 MeV J-PARC radio frequency quadrupole linac (M. Ikegami et al., Proc. 2003 Part. Accel. Conf. 2003, p. 1509). The process of the optimization, which confirms the validity of hypothesis that H- ions are produced by surface reaction on a Mo plasma electrode dominantly in the ion source, is presented.

Effect of pulse electric fields (PEF) on accumulation of magnesium and zinc ions in Saccharomyces cerevisiae cells.

PubMed

Pankiewicz, Urszula; Sujka, Monika; Włodarczyk-Stasiak, Marzena; Mazurek, Artur; Jamroz, Jerzy

2014-08-15

Cultures of Saccharomyces cerevisiae were treated with PEF to improve simultaneous accumulation of magnesium and zinc ions in the biomass. The results showed that the ions concentration in the medium and their mutual interactions affect accumulation in cells. Increasing the concentration of one ion in the medium reduced the accumulation of the second one, in the control as well as in the cells treated with PEF. Under optimized conditions, that is, on 15 min exposure of the 20 h grown culture to PEF of 5.0 kV/cm and 20 μs pulse width, accumulation of magnesium and zinc in yeast biomass reached maximum levels of 2.85 and 11.41 mg/gd.m., respectively, To summarize, optimization of ion pair concentration and PEF parameters caused a 1.5 or 2-fold increase of magnesium and zinc accumulation, respectively, in S. cerevisiae. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fine structure of modal focusing effect in a three dimensional plasma-sheath-lens formed by disk electrodes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stamate, Eugen, E-mail: eust@dtu.dk; Venture Business Laboratory, Nagoya University, C3-1, Chikusa-ku, Nagoya 464-8603; Yamaguchi, Masahito

2015-08-31

Modal and discrete focusing effects associated with three-dimensional plasma-sheath-lenses show promising potential for applications in ion beam extraction, mass spectrometry, plasma diagnostics and for basic studies of plasma sheath. The ion focusing properties can be adjusted by controlling the geometrical structure of the plasma-sheath-lens and plasma parameters. The positive and negative ion kinetics within the plasma-sheath-lens are investigated both experimentally and theoretically and a modal focusing ring is identified on the surface of disk electrodes. The focusing ring is very sensitive to the sheath thickness and can be used to monitor very small changes in plasma parameters. Three dimensional simulationsmore » are found to be in very good agreement with experiments.« less

Live cell imaging at the Munich ion microbeam SNAKE - a status report.

PubMed

Drexler, Guido A; Siebenwirth, Christian; Drexler, Sophie E; Girst, Stefanie; Greubel, Christoph; Dollinger, Günther; Friedl, Anna A

2015-02-18

Ion microbeams are important tools in radiobiological research. Still, the worldwide number of ion microbeam facilities where biological experiments can be performed is limited. Even fewer facilities combine ion microirradiation with live-cell imaging to allow microscopic observation of cellular response reactions starting very fast after irradiation and continuing for many hours. At SNAKE, the ion microbeam facility at the Munich 14 MV tandem accelerator, a large variety of biological experiments are performed on a regular basis. Here, recent developments and ongoing research projects at the ion microbeam SNAKE are presented with specific emphasis on live-cell imaging experiments. An overview of the technical details of the setup is given, including examples of suitable biological samples. By ion beam focusing to submicrometer beam spot size and single ion detection it is possible to target subcellular structures with defined numbers of ions. Focusing of high numbers of ions to single spots allows studying the influence of high local damage density on recruitment of damage response proteins.

Ion extraction from a plasma

NASA Technical Reports Server (NTRS)

Aston, G.; Wilbur, P. J.

1981-01-01

The physical processes governing ion extraction from a plasma have been examined experimentally. The screen hole plasma sheath (the transition region wherein significant ion acceleration and complete electron retardation occurs) has been defined by equipotential plots for a variety of ion accelerator system geometries and operating conditions. It was found that the screen hole plasma sheath extends over a large distance, and influences ion and electron trajectories at least 15 Debye lengths within the discharge chamber. The electron density variation within the screen hole plasma sheath satisfied a Maxwell-Boltzmann density distribution at an effective electron temperature dependent on the discharge plasma primary-to-Maxwellian electron density ratio. Plasma ion flow up to and through the sheath was predominantly one-dimensional, and the ions entered the sheath region with a modified Bohm velocity. Low values of the screen grid thickness to screen hole diameter ratio were found to give good ion focusing and high extracted ion currents because of the effect of screen webbing on ion focusing.

Metallic ions as therapeutic agents in tissue engineering scaffolds: an overview of their biological applications and strategies for new developments

PubMed Central

Mouriño, Viviana; Cattalini, Juan Pablo; Boccaccini, Aldo R.

2012-01-01

This article provides an overview on the application of metallic ions in the fields of regenerative medicine and tissue engineering, focusing on their therapeutic applications and the need to design strategies for controlling the release of loaded ions from biomaterial scaffolds. A detailed summary of relevant metallic ions with potential use in tissue engineering approaches is presented. Remaining challenges in the field and directions for future research efforts with focus on the key variables needed to be taken into account when considering the controlled release of metallic ions in tissue engineering therapeutics are also highlighted. PMID:22158843

Ion beam accelerator system

NASA Technical Reports Server (NTRS)

Aston, G. (Inventor)

1981-01-01

A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids with multiple pairs of aligned holes positioned to direct a group of beamlets along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam. An accelerator electrode device downstream from the extraction grids is at a much lower potential than the grids to accelerate the combined beam. The application of the system to ion implantation is mentioned.

Complexities of Focused Ion Beam Preparation of Electron-Transparent Sections for Meteorite Studies

NASA Astrophysics Data System (ADS)

Ishii, H. A.; Bradley, J. P.; Teslich, N.

2012-09-01

Focused Ion Beam is increasingly used to prepare site-specific, electron-transparent sections for meteorite micro-texture and -chemistry studies. We discuss technical challenges and frequently-overlooked FIB artifacts relevant to meteorite analyses.

Pulsed-voltage atom probe tomography of low conductivity and insulator materials by application of ultrathin metallic coating on nanoscale specimen geometry.

PubMed

Adineh, Vahid R; Marceau, Ross K W; Chen, Yu; Si, Kae J; Velkov, Tony; Cheng, Wenlong; Li, Jian; Fu, Jing

2017-10-01

We present a novel approach for analysis of low-conductivity and insulating materials with conventional pulsed-voltage atom probe tomography (APT), by incorporating an ultrathin metallic coating on focused ion beam prepared needle-shaped specimens. Finite element electrostatic simulations of coated atom probe specimens were performed, which suggest remarkable improvement in uniform voltage distribution and subsequent field evaporation of the insulated samples with a metallic coating of approximately 10nm thickness. Using design of experiment technique, an experimental investigation was performed to study physical vapor deposition coating of needle specimens with end tip radii less than 100nm. The final geometries of the coated APT specimens were characterized with high-resolution scanning electron microscopy and transmission electron microscopy, and an empirical model was proposed to determine the optimal coating thickness for a given specimen size. The optimal coating strategy was applied to APT specimens of resin embedded Au nanospheres. Results demonstrate that the optimal coating strategy allows unique pulsed-voltage atom probe analysis and 3D imaging of biological and insulated samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Determination of Inorganic Cations and Anions in Chitooligosaccharides by Ion Chromatography with Conductivity Detection.

PubMed

Cao, Lidong; Li, Xiuhuan; Fan, Li; Zheng, Li; Wu, Miaomiao; Zhang, Shanxue; Huang, Qiliang

2017-02-22

Chitooligosaccharides (COSs) are a promising drug candidate and food ingredient because they are innately biocompatible, non-toxic, and non-allergenic to living tissues. Therefore, the impurities in COSs must be clearly elucidated and precisely determined. As for COSs, most analytical methods focus on the determination of the average degrees of polymerization (DPs) and deacetylation (DD), as well as separation and analysis of the single COSs with different DPs. However, little is known about the concentrations of inorganic cations and anions in COSs. In the present study, an efficient and sensitive ion chromatography coupled with conductivity detection (IC-CD) for the determination of inorganic cations Na⁺, NH₄⁺, K⁺, Mg 2+ , Ca 2+ , and chloride, acetate and lactate anions was developed. Detection limits were 0.01-0.05 μM for cations and 0.5-0.6 μM for anions. The linear range was 0.001-0.8 mM. The optimized analysis was carried out on IonPac CS12A and IonPac AS12A analytical column for cations and anions, respectively, using isocratic elution with 20 mM methanesulfonic acid and 4 mM sodium hydroxide aqueous solution as the mobile phase at a 1.0 mL/min flow rate. Quality parameters, including precision and accuracy, were fully validated and found to be satisfactory. The fully validated IC-CD method was readily applied for the quantification of various cations and anions in commercial COS technical concentrate.

Determination of Inorganic Cations and Anions in Chitooligosaccharides by Ion Chromatography with Conductivity Detection

PubMed Central

Cao, Lidong; Li, Xiuhuan; Fan, Li; Zheng, Li; Wu, Miaomiao; Zhang, Shanxue; Huang, Qiliang

2017-01-01

Chitooligosaccharides (COSs) are a promising drug candidate and food ingredient because they are innately biocompatible, non-toxic, and non-allergenic to living tissues. Therefore, the impurities in COSs must be clearly elucidated and precisely determined. As for COSs, most analytical methods focus on the determination of the average degrees of polymerization (DPs) and deacetylation (DD), as well as separation and analysis of the single COSs with different DPs. However, little is known about the concentrations of inorganic cations and anions in COSs. In the present study, an efficient and sensitive ion chromatography coupled with conductivity detection (IC-CD) for the determination of inorganic cations Na+, NH4+, K+, Mg2+, Ca2+, and chloride, acetate and lactate anions was developed. Detection limits were 0.01–0.05 μM for cations and 0.5–0.6 μM for anions. The linear range was 0.001–0.8 mM. The optimized analysis was carried out on IonPac CS12A and IonPac AS12A analytical column for cations and anions, respectively, using isocratic elution with 20 mM methanesulfonic acid and 4 mM sodium hydroxide aqueous solution as the mobile phase at a 1.0 mL/min flow rate. Quality parameters, including precision and accuracy, were fully validated and found to be satisfactory. The fully validated IC-CD method was readily applied for the quantification of various cations and anions in commercial COS technical concentrate. PMID:28241416

Balancing the Interactions of Ions, Water, and DNA in the Drude Polarizable Force Field

PubMed Central

2015-01-01

Recently we presented a first-generation all-atom Drude polarizable force field for DNA based on the classical Drude oscillator model, focusing on optimization of key dihedral angles followed by extensive validation of the force field parameters. Presently, we describe the procedure for balancing the electrostatic interactions between ions, water, and DNA as required for development of the Drude force field for DNA. The proper balance of these interactions is shown to impact DNA stability and subtler conformational properties, including the conformational equilibrium between the BI and BII states, and the A and B forms of DNA. The parametrization efforts were simultaneously guided by gas-phase quantum mechanics (QM) data on small model compounds and condensed-phase experimental data on the hydration and osmotic properties of biologically relevant ions and their solutions, as well as theoretical predictions for ionic distribution around DNA oligomer. In addition, fine-tuning of the internal base parameters was performed to obtain the final DNA model. Notably, the Drude model is shown to more accurately reproduce counterion condensation theory predictions of DNA charge neutralization by the condensed ions as compared to the CHARMM36 additive DNA force field, indicating an improved physical description of the forces dictating the ionic solvation of DNA due to the explicit treatment of electronic polarizability. In combination with the polarizable DNA force field, the availability of Drude polarizable parameters for proteins, lipids, and carbohydrates will allow for simulation studies of heterogeneous biological systems. PMID:24874104

Breakthrough in 4π ion emission mechanism understanding in plasma focus devices.

PubMed

Sohrabi, Mehdi; Zarinshad, Arefe; Habibi, Morteza

2016-12-12

Ion emission angular distribution mechanisms in plasma focus devices (PFD) have not yet been well developed and understood being due to the lack of an efficient wide-angle ion distribution image detection system to characterize a PFD space in detail. Present belief is that the acceleration of ions points from "anode top" upwards in forward direction within a small solid angle. A breakthrough is reported in this study, by mega-size position-sensitive polycarbonate ion image detection systems invented, on discovery of 4π ion emission from the "anode top" in a PFD space after plasma pinch instability and radial run-away of ions from the "anode cathodes array" during axial acceleration of plasma sheaths before the radial phase. These two ion emission source mechanisms behave respectively as a "Point Ion Source" and a "Line Ion Source" forming "Ion Cathode Shadows" on mega-size detectors. We believe that the inventions and discoveries made here will open new horizons for advanced ion emission studies towards better mechanisms understanding and in particular will promote efficient applications of PFDs in medicine, science and technology.

Large Area Microcorrals and Cavity Formation on Cantilevers using a Focused Ion Beam

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saraf, Laxmikant V.; Britt, David W.

2011-09-14

We utilize focused ion beam (FIB) to explore various sputtering parameters to form large area microcorrals and cavities on cantilevers. Microcorrals were rapidly created by modifying ion beam blur and overlaps. Modification in FIB sputtering parameters affects the periodicity and shape of corral microstructure. Cantilever deflections show ion beam amorphization effects as a function of sputtered area and cantilever base cavities with or without side walls. The FIB sputtering parameters address a method for rapid creation of a cantilever tensiometer with integrated fluid storage and delivery.

Amorphization induced by focused ion beam milling in metallic and electronic materials.

PubMed

Huh, Yoon; Hong, Ki Jung; Shin, Kwang Soo

2013-08-01

Focused ion beam (FIB) milling using high-energy gallium ions is widely used in the preparation of specimens for transmission electron microscopy (TEM). However, the energetic ion beam induces amorphization on the edge of specimens during milling, resulting in a mischievous influence on the clearness of high-quality transmission electron micrographs. In this work, the amorphization induced by the FIB milling was investigated by TEM for three kinds of materials, metallic materials in bulk shape, and semiconductive and electronic ceramic materials as a substrate for the deposition of thin films.

Ion extraction from a plasma. Ph.D. Thesis. Progress Report, 1 Dec. 1979 - 1 Dec. 1980

NASA Technical Reports Server (NTRS)

Aston, G.

1980-01-01

An experimental investigation of the physical processes governing ion extraction from a plasma is presented. The screen hole plasma sheath of a multiaperture ion accelerator system is defined by equipotential plots for a variety of accelerator system geometries and operating conditions. A sheath thickness of at least fifteen Debye lengths is shown to be typical. The electron density variation within the sheath satisfies a Maxwell Boltzmann density distribution at an effective electron temperature dependent on the discharge plasma primary to Maxwellian electron density ratio. Plasma ion flow up to and through the sheath is predominately one dimensional and the ions enter the sheath with a modified Bohm velocity. Low values of the screen grid thickness to screen hole diameter ratio give good ion focusing and high extracted ion currents because of the effect of screen webbing on ion focusing.

Fast Faraday cup for fast ion beam TOF measurements in deuterium filled plasma focus device and correlation with Lee model

NASA Astrophysics Data System (ADS)

Damideh, Vahid; Ali, Jalil; Saw, Sor Heoh; Rawat, Rajdeep Singh; Lee, Paul; Chaudhary, Kashif Tufail; Rizvi, Zuhaib Haider; Dabagh, Shadab; Ismail, Fairuz Diyana; Sing, Lee

2017-06-01

In this work, the design and construction of a 50 Ω fast Faraday cup and its results in correlation with the Lee Model Code for fast ion beam and ion time of flight measurements for a Deuterium filled plasma focus device are presented. Fast ion beam properties such as ion flux, fluence, speed, and energy at 2-8 Torr Deuterium are studied. The minimum 34 ns full width at half maximum ion signal at 12 kV, 3 Torr Deuterium in INTI PF was captured by a Faraday cup. The maximum ion energy of 67 ± 5 keV at 4 Torr Deuterium was detected by the Faraday cup. Ion time of flight measurements by the Faraday cup show consistent correlation with Lee Code results for Deuterium especially at near to optimum pressures.

Investigation of the ion beam emission from a pulsed power plasma device

NASA Astrophysics Data System (ADS)

Henríquez, A.; Bhuyan, H.; Favre, M.; Retamal, M. J.; Volkmann, U.; Wyndham, E.; Chuaqui, H.

2014-05-01

Plasma Focus (PF) devices are well known as ion beam sources with characteristic energy among the hundreds of keV to tens of MeV. The information on ion beam energy, ion distribution and composition is essential from the viewpoint of understanding fundamental physics behind their production and acceleration and also their applications in various fields, such as surface properties modification, ion implantation, thin film deposition, semiconductor doping and ion assisted coating. An investigation from a low energy, 1.8 kJ 160 kA, Mather type plasma focus device operating with nitrogen using CR-39 detectors was conducted to study the emission of ions at different angular positions. Tracks on CR-39 detectors at different angular positions reveal the existence of angular ion anisotropy. The results obtained are comparable with the time integrated measurements using FC. Preliminary results of this work are presented.

Insight into fast ion migration kinetics of a new hybrid single Li-ion conductor based on aluminate complexes for solid-state Li-ion batteries.

PubMed

Feng, Yancong; Tan, Rui; Zhao, Yan; Gao, Rongtan; Yang, Luyi; Yang, Jinlong; Li, Hao; Zhou, Guofu; Chen, Haibiao; Pan, Feng

2018-03-29

A novel hybrid single Li-ion conductor (SLIC) for a Li-ion solid electrolyte was prepared by mixing aluminate complexes-polyethylene glycol (LiAl-PEG) and polyethylene oxide (PEO) for solid-state Li-ion batteries. The LiAl-PEG/PEO blend possesses high thermal stability and electrochemical stability with an oxidation decomposition voltage up to 4.8 V. Notably, this hybrid SLIC exhibits not only excellent Li-ion migration kinetics, but also good ionic conductivity as high as 4.0 × 10-5 and 2.6 × 10-4 S cm-1 at 30 and 100 °C, respectively, which is much higher than previously reported SLICs. Importantly, by the combination of molecular dynamics simulations and experiment measurements, the mechanisms of Li-ion migration across the SLIC (LiAl-PEG), the salt-in-polymer (LiClO4/PEO) and the optimized SLIC (LiAl-PEG/PEO) were systematically investigated for the first time. The new hopping transport mechanism was verified for the SLIC system at the nanoscale. As for the hybrid SLIC, PEO chains enhance the segmental mobility of the ether-chains bonded with Al atoms, improve the ionicity, and provide extra ionic paths for Li transfer, resulting in the optimized Li-ion migration kinetics of LiAl-PEG/PEO.

Control and System Theory, Optimization, Inverse and Ill-Posed Problems

DTIC Science & Technology

1988-09-14

Justlfleatlen Distribut ion/ Availability Codes # AFOSR-87-0350 Avat’ and/or1987-1988 Dist Special *CONTROL AND SYSTEM THEORY , ~ * OPTIMIZATION, * INVERSE...considerable va- riety of research investigations within the grant areas (Control and system theory , Optimization, and Ill-posed problems]. The

Enhanced collective focusing of intense neutralized ion beam pulses in the presence of weak solenoidal magnetic fields

DOE PAGES

Dorf, Mikhail A.; Davidson, Ronald C.; Kaganovich, Igor D.; ...

2012-05-31

In this study, the design of ion drivers for warm dense matter and high energy density physics applications and heavy ion fusion involves transverse focusing and longitudinal compression of intense ion beams to a small spot size on the target. To facilitate the process, the compression occurs in a long drift section filled with a dense background plasma, which neutralizes the intense beam self-fields. Typically, the ion bunch charge is better neutralized than its current, and as a result a net self-pinching (magnetic) force is produced. The self-pinching effect is of particular practical importance, and is used in various ionmore » driver designs in order to control the transverse beam envelope. In the present work we demonstrate that this radial self-focusing force can be significantly enhanced if a weak (B~100 G) solenoidal magnetic field is applied inside the neutralized drift section, thus allowing for substantially improved transport. It is shown that in contrast to magnetic self-pinching, the enhanced collective self-focusing has a radial electric field component and occurs as a result of the overcompensation of the beam charge by plasmaelectrons, whereas the beam current becomes well-neutralized. As the beam leaves the neutralizing drift section, additional transverse focusing can be applied. For instance, in the neutralized drift compression experiments (NDCX) a strong (several Tesla) final focus solenoid is used for this purpose. In the present analysis we propose that the tight final focus in the NDCX experiments may possibly be achieved by using a much weaker (few hundred Gauss) magnetic lens, provided the ion beam carries an equal amount of co-moving neutralizing electrons from the preceding drift section into the lens. In this case the enhanced focusing is provided by the collective electrondynamics strongly affected by a weak applied magnetic field.« less

Rapid Prototyping across the Spectrum: RF to Optical 3D Electromagnetic Structures

DTIC Science & Technology

2015-11-17

34Imprintable, Bendable, and Shape-Conformable Polymer Electrolytes for Versatile-Shaped Lithium - Ion Batteries ," Advanced Materials, vol. 25, pp. 1395-1400...center; and (d) close-up of light aperture etched with a focused ion beam [104] ............ 22 Figure 16: (a) Conformal antenna patterned by...where the features are defined using focused ion beam milling (e.g. fishnet patterns) [20], standard micro-/nano- lithography processes that are

Mass Spectrometry Parameters Optimization for the 46 Multiclass Pesticides Determination in Strawberries with Gas Chromatography Ion-Trap Tandem Mass Spectrometry

NASA Astrophysics Data System (ADS)

Fernandes, Virgínia C.; Vera, Jose L.; Domingues, Valentina F.; Silva, Luís M. S.; Mateus, Nuno; Delerue-Matos, Cristina

2012-12-01

Multiclass analysis method was optimized in order to analyze pesticides traces by gas chromatography with ion-trap and tandem mass spectrometry (GC-MS/MS). The influence of some analytical parameters on pesticide signal response was explored. Five ion trap mass spectrometry (IT-MS) operating parameters, including isolation time (IT), excitation voltage (EV), excitation time (ET), maximum excitation energy or " q" value (q), and isolation mass window (IMW) were numerically tested in order to maximize the instrument analytical signal response. For this, multiple linear regression was used in data analysis to evaluate the influence of the five parameters on the analytical response in the ion trap mass spectrometer and to predict its response. The assessment of the five parameters based on the regression equations substantially increased the sensitivity of IT-MS/MS in the MS/MS mode. The results obtained show that for most of the pesticides, these parameters have a strong influence on both signal response and detection limit. Using the optimized method, a multiclass pesticide analysis was performed for 46 pesticides in a strawberry matrix. Levels higher than the limit established for strawberries by the European Union were found in some samples.

Ion funnel ion trap and process

DOEpatents

Belov, Mikhail E [Richland, WA; Ibrahim, Yehia M [Richland, WA; Clowers, Biran H [West Richland, WA; Prior, David C [Hermiston, OR; Smith, Richard D [Richland, WA

2011-02-15

An ion funnel trap is described that includes a inlet portion, a trapping portion, and a outlet portion that couples, in normal operation, with an ion funnel. The ion trap operates efficiently at a pressure of .about.1 Torr and provides for: 1) removal of low mass-to-charge (m/z) ion species, 2) ion accumulation efficiency of up to 80%, 3) charge capacity of .about.10,000,000 elementary charges, 4) ion ejection time of 40 to 200 .mu.s, and 5) optimized variable ion accumulation times. Ion accumulation with low concentration peptide mixtures has shown an increase in analyte signal-to-noise ratios (SNR) of a factor of 30, and a greater than 10-fold improvement in SNR for multiply charged analytes.

Battery Control Algorithms | Transportation Research | NREL

Science.gov Websites

publications. Accounting for Lithium-Ion Battery Degradation in Electric Vehicle Charging Optimization Advanced Reformulation of Lithium-Ion Battery Models for Enabling Electric Transportation Fail-Safe Design for Large Capacity Lithium-Ion Battery Systems Contact Ying Shi Email | 303-275-4240

Free Fe(3+)/Fe(2+) improved the biomass resource recovery and organic matter removal in Rhodobacter sphaeroides purification of sewage.

PubMed

Liu, Rijia; Wu, Pan; Lang, Lang; Xu, Changru; Wang, Yanling

2016-01-01

The enhancement in biomass production and organic matter removal of Rhodobacter sphaeroides (R. sphaeroides) through iron ions in soybean protein wastewater treatment was investigated. Different dosages of ferric ions were introduced in the reactors under light-anaerobic conditions. Free ferric and ferrous ions in wastewater were formed and their concentrations were the optimal for the growth of R. sphaeroides when the total Fe dosage was 20 mg/L. At the optimal dosage, biomass production (4000 mg/L) and protease activity improved by 50% and 48% when compared to the controls, respectively. The organic matter and protein removal reached above 90% and hydraulic retention time was shortened from 96 to 72 h. A mechanism analysis indicated that iron ions can effectively improve the adenosine triphosphate production, which may furthermore encourage the synthesis of protease and the cellular material.

Inert gas ion thruster development

NASA Technical Reports Server (NTRS)

Ramsey, W. D.

1980-01-01

Two 12 cm magneto-electrostatic containment (MESC) ion thrusters were performance mapped with argon and xenon. The first, hexagonal, thruster produced optimized performance of 48.5to 79 percent argon mass utilization efficiencies at discharge energies of 240 to 425 eV/ion, respectively, Xenon mass utilization efficiencies of 78 to 95 percent were observed at discharge energies of 220 to 290 eV/ion with the same optimized hexagonal thruster. Changes to the cathode baffle reduced the discharge anode potential during xenon operation from approximately 40 volts to about 30 volts. Preliminary tests conducted with the second, hemispherical, MESC thruster showed a nonuniform anode magnetic field adversely affected thruster performance. This performance degradation was partially overcome by changes in the boundary anode placement. Conclusions drawn the hemispherical thruster tests gave insights into the plasma processes in the MESC discharge that will aid in the design of future thrusters.

Ion acceleration in electrostatic collisionless shock: on the optimal density profile for quasi-monoenergetic beams

NASA Astrophysics Data System (ADS)

Boella, E.; Fiúza, F.; Stockem Novo, A.; Fonseca, R.; Silva, L. O.

2018-03-01

A numerical study on ion acceleration in electrostatic shock waves is presented, with the aim of determining the best plasma configuration to achieve quasi-monoenergetic ion beams in laser-driven systems. It was recently shown that tailored near-critical density plasmas characterized by a long-scale decreasing rear density profile lead to beams with low energy spread (Fiúza et al 2012 Phys. Rev. Lett. 109 215001). In this work, a detailed parameter scan investigating different plasma scale lengths is carried out. As result, the optimal plasma spatial scale length that allows for minimizing the energy spread while ensuring a significant reflection of ions by the shock is identified. Furthermore, a new configuration where the required profile has been obtained by coupling micro layers of different densities is proposed. Results show that this new engineered approach is a valid alternative, guaranteeing a low energy spread with a higher level of controllability.

Plasma focus ion beam-scaling laws

NASA Astrophysics Data System (ADS)

Saw, S. H.

2014-08-01

Measurements on plasma focus ion beams include various advanced techniques producing a variety of data which has yet to produce benchmark numbers. Recent numerical experiments using an extended version of the Lee Code has produced reference numbers and scaling trends for number and energy fluence of deuteron beams as functions of stored energy E0. At the pinch exit the ion number fluence (ions m-2) and energy fluence (J m-2) computed as 2.4-7.8×1020 and 2.2-33×106 respectively were found to be independent of E0 from 0.4 - 486 kJ. This work was extended to the ion beams for various gases. The results show that, for a given plasma focus, the fluence, flux, ion number and ion current decrease from the lightest to the heaviest gas except for trend-breaking higher values for Ar fluence and flux. The energy fluence, energy flux, power flow and damage factors are relatively constant from H2 to N2 but increase for Ne, Ar, Kr and Xe due to radiative cooling and collapse effects. This paper reviews this work and in a concluding section attempts to put the accumulating large amounts of data into the form of a scaling law of beam energy Ebeam versus storage energy E0 taking the form for deuteron as: {Ebeam} = 18.2{E}01.23; where Ebeam is in J and E0 is in kJ. It is hoped that the establishment of such scaling laws places on a firm footing the reference quantitative ideas for plasma focus ion beams.

High current density ion beam obtained by a transition to a highly focused state in extremely low-energy region

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirano, Y., E-mail: y.hirano@aist.go.jp, E-mail: hirano.yoichi@phys.cst.nihon-u.ac.jp; College of Science and Technologies, Nihon University, Chiyodaku, Tokyo 101-0897; Kiyama, S.

2015-11-15

A high current density (≈3 mA/cm{sup 2}) hydrogen ion beam source operating in an extremely low-energy region (E{sub ib} ≈ 150–200 eV) has been realized by using a transition to a highly focused state, where the beam is extracted from the ion source chamber through three concave electrodes with nominal focal lengths of ≈350 mm. The transition occurs when the beam energy exceeds a threshold value between 145 and 170 eV. Low-level hysteresis is observed in the transition when E{sub ib} is being reduced. The radial profiles of the ion beam current density and the low temperature ion current densitymore » can be obtained separately using a Faraday cup with a grid in front. The measured profiles confirm that more than a half of the extracted beam ions reaches the target plate with a good focusing profile with a full width at half maximum of ≈3 cm. Estimation of the particle balances in beam ions, the slow ions, and the electrons indicates the possibility that the secondary electron emission from the target plate and electron impact ionization of hydrogen may play roles as particle sources in this extremely low-energy beam after the compensation of beam ion space charge.« less

Development of light ion therapy at the Karolinska Hospital and Institute.

PubMed

Svensson, Hans; Ringborg, Ulrik; Näslund, Ingemar; Brahme, Anders

2004-12-01

Recent developments in radiation therapy have made it possible to optimize the high dose region to cover almost any target volume and shape at the same time as the dose level to adjacent organs at risk is acceptable. Further implementations of IMRT (Intensity Modulated Radiation Therapy), and inverse treatment planning using already available technologies but also foreseeable improved design of therapy accelerators delivering electron- and photon beams, will bring these advances to the benefit of a broad population of cancer patients. Protons will therefore generally not be needed since in most situations the improvement will be insignificant or moderate due to the large lateral penumbra with deep proton therapy. A further step would be to use He-ions, which have only half the penumbra width of protons and still a fairly low-LET in the spread-out Bragg peak. There is however still a group of patients that cannot be helped by these advances as the tumor might be radioresistant for the presently utilized low ionization density beam qualities. The ultimate step in the therapy development process should therefore be to optimize the beam quality for each tumor-normal tissue situation. To facilitate beam quality optimization light ions are needed. It is argued that in many radioresistant tumors a dose-mean LET of 25-50 eV/nm in the target would be optimum as then tumor cells will be lost in the highest proportion through apoptotic cell kill and the superficial tissues will still be irradiated with a fairly low LET. Light ions using Li, Be, B, and C would then be the ideal choice. In this paper a light ion facility is outlined for the Karolinska University Hospital facilitating both dose distribution and beam quality optimization.

Rod-filter-field optimization of the J-PARC RF-driven H{sup −} ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueno, A., E-mail: akira.ueno@j-parc.jp; Ohkoshi, K.; Ikegami, K.

2015-04-08

In order to satisfy the Japan Proton Accelerator Research Complex (J-PARC) second-stage requirements of an H{sup −} ion beam of 60mA within normalized emittances of 1.5πmm•mrad both horizontally and vertically, a flat top beam duty factor of 1.25% (500μs×25Hz) and a life-time of longer than 1month, the J-PARC cesiated RF-driven H{sup −} ion source was developed by using an internal-antenna developed at the Spallation Neutron Source (SNS). Although rod-filter-field (RFF) is indispensable and one of the most beam performance dominative parameters for the RF-driven H{sup −} ion source with the internal-antenna, the procedure to optimize it is not established. Inmore » order to optimize the RFF and establish the procedure, the beam performances of the J-PARC source with various types of rod-filter-magnets (RFMs) were measured. By changing RFM’s gap length and gap number inside of the region projecting the antenna inner-diameter along the beam axis, the dependence of the H{sup −} ion beam intensity on the net 2MHz-RF power was optimized. Furthermore, the fine-tuning of RFM’s cross-section (magnetmotive force) was indispensable for easy operation with the temperature (T{sub PE}) of the plasma electrode (PE) lower than 70°C, which minimizes the transverse emittances. The 5% reduction of RFM’s cross-section decreased the time-constant to recover the cesium effects after an slightly excessive cesiation on the PE from several 10 minutes to several minutes for T{sub PE} around 60°C.« less

Development of an inertial confinement fusion platform to study charged-particle-producing nuclear reactions relevant to nuclear astrophysics

DOE PAGES

Gatu Johnson, M.; Zylstra, A. B.; Bacher, A.; ...

2017-03-28

Here, this paper describes the development of a platform to study astrophysically relevant nuclear reactions using inertial-confinement fusion implosions on the OMEGA and National Ignition Facility laser facilities, with a particular focus on optimizing the implosions to study charged-particle- producing reactions. Primary requirements on the platform are high yield, for high statistics in the fusion product measurements, combined with low areal density, to allow the charged fusion products to escape. This is optimally achieved with direct-drive exploding pusher implosions using thin-glass-shell capsules. Mitigation strategies to eliminate a possible target sheath potential which would accelerate the emitted ions are discussed. Themore » potential impact of kinetic effects on the implosions is also considered. The platform is initially employed to study the complementary T(t,2n)α, T( 3He,np)α and 3He( 3He,2p)α reactions. Proof-of-principle results from the first experiments demonstrating the ability to accurately measure the energy and yields of charged particles are presented. Lessons learned from these experiments will be used in studies of other reactions. Ultimately, the goals are to explore thermonuclear reaction rates and fundamental nuclear physics in stellarlike plasma environments, and to push this new frontier of nuclear astrophysics into unique regimes not reachable through existing platforms, with thermal ion velocity distributions, plasma screening, and low reactant energies.« less

Pre-equilibrium dynamics and heavy-ion observables

NASA Astrophysics Data System (ADS)

Heinz, Ulrich; Liu, Jia

2016-12-01

To bracket the importance of the pre-equilibrium stage on relativistic heavy-ion collision observables, we compare simulations where it is modeled by either free-streaming partons or fluid dynamics. These cases implement the assumptions of extremely weak vs. extremely strong coupling in the initial collision stage. Accounting for flow generated in the pre-equilibrium stage, we study the sensitivity of radial, elliptic and triangular flow on the switching time when the hydrodynamic description becomes valid. Using the hybrid code iEBE-VISHNU [C. Shen, Z. Qiu, H. Song, J. Bernhard, S. Bass and U. Heinz, Comput. Phys. Commun. 199 (2016) 61] we perform a multi-parameter search, constrained by particle ratios, integrated elliptic and triangular charged hadron flow, the mean transverse momenta of pions, kaons and protons, and the second moment < pT2 > of the proton transverse momentum spectrum, to identify optimized values for the switching time τs from pre-equilibrium to hydrodynamics, the specific shear viscosity η / s, the normalization factor of the temperature-dependent specific bulk viscosity (ζ / s) (T), and the switching temperature Tsw from viscous hydrodynamics to the hadron cascade UrQMD. With the optimized parameters, we predict and compare with experiment the pT-distributions of π, K, p, Λ, Ξ and Ω yields and their elliptic flow coefficients, focusing specifically on the mass-ordering of the elliptic flow for protons and Lambda hyperons which is incorrectly described by VISHNU without pre-equilibrium flow.

A GDT-based fusion neutron source for academic and industrial applications

NASA Astrophysics Data System (ADS)

Anderson, J. K.; Forest, C. B.; Mirnov, V. V.; Peterson, E. E.; Waleffe, R.; Wallace, J.; Harvey, R. W.

2017-10-01

The design of a fusion neutron source based on the gas dynamic trap (GDT) configuration is underway. The motivation is both the ends and the means. There are immediate applications for neutrons including medical isotope production and actinide burners. Taking the next step in the magnetic mirror path will leverage advances in high-temperature superconducting magnets and additive manufacturing in confining a fusion plasma, and both the technological and physics bases exist. Recent breakthrough results at the GDT facility in Russia demonstrate stable confinement of a beta 60% mirror plasma at high Te ( 1 keV). These scale readily to a fusion neutron source with an increase in magnetic field, mirror ratio, and ion energy. Studies of a next-step compact device focus on calculations of MHD equilibrium and stability, and Fokker-Planck modeling to optimize the heating scenario. The conceptualized device uses off-the-shelf MRI magnets for a 1 T central field, REBCO superconducting mirror coils (which can currently produce fields in excess of 30T), and existing 75 keV NBI and 140 GHz ECRH. High harmonic fast wave injection is damped on beam ions, dramatically increasing the fusion reactivity for an incremental bump in input power. MHD stability is achieved with the vortex confinement scheme, where a biasing profile imposes optimal ExB rotation of the plasma. Liquid metal divertors are being considered in the end cells. Work supported by the Wisconsin Alumni Research Foundation.

Development of an inertial confinement fusion platform to study charged-particle-producing nuclear reactions relevant to nuclear astrophysics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gatu Johnson, M.; Zylstra, A. B.; Bacher, A.

Here, this paper describes the development of a platform to study astrophysically relevant nuclear reactions using inertial-confinement fusion implosions on the OMEGA and National Ignition Facility laser facilities, with a particular focus on optimizing the implosions to study charged-particle- producing reactions. Primary requirements on the platform are high yield, for high statistics in the fusion product measurements, combined with low areal density, to allow the charged fusion products to escape. This is optimally achieved with direct-drive exploding pusher implosions using thin-glass-shell capsules. Mitigation strategies to eliminate a possible target sheath potential which would accelerate the emitted ions are discussed. Themore » potential impact of kinetic effects on the implosions is also considered. The platform is initially employed to study the complementary T(t,2n)α, T( 3He,np)α and 3He( 3He,2p)α reactions. Proof-of-principle results from the first experiments demonstrating the ability to accurately measure the energy and yields of charged particles are presented. Lessons learned from these experiments will be used in studies of other reactions. Ultimately, the goals are to explore thermonuclear reaction rates and fundamental nuclear physics in stellarlike plasma environments, and to push this new frontier of nuclear astrophysics into unique regimes not reachable through existing platforms, with thermal ion velocity distributions, plasma screening, and low reactant energies.« less

Analytical performance of a versatile laboratory microscopic X-ray fluorescence system for metal uptake studies on argillaceous rocks

NASA Astrophysics Data System (ADS)

Gergely, Felicián; Osán, János; Szabó, B. Katalin; Török, Szabina

2016-02-01

Laboratory-scale microscopic X-ray fluorescence (micro-XRF) plays an increasingly important role in various fields where multielemental investigations of samples are indispensable. In case of geological samples, the reasonable detection limits (LOD) and spatial resolutions are necessary to identify the trace element content in microcrystalline level. The present study focuses on the analytical performance of a versatile laboratory-scale micro-XRF system with various options of X-ray sources and detectors to find the optimal experimental configuration in terms of sensitivities and LOD for selected elements in loaded petrographic thin sections. The method was tested for sorption studies involving thin sections prepared from cores of Boda Claystone Formation, which is a potential site for a high-level radioactive waste repository. Loaded ions in the sorption measurements were Cs(I) and Ni(II) chemically representing fission and corrosion products. Based on the collected elemental maps, the correlation between the elements representative of main rock components and the selected loaded ion was studied. For the elements of interest, Cs(I) and Ni(II) low-power iMOXS source with polycapillary and silicon drift detector was found to be the best configuration to reach the optimal LOD values. Laboratory micro-XRF was excellent to identify the responsible key minerals for the uptake of Cs(I). In case of nickel, careful corrections were needed because of the relatively high Ca content of the rock samples. The results were compared to synchrotron radiation micro-XRF.

Highly charged ion beams and their applications

NASA Astrophysics Data System (ADS)

Marler, Joan

2018-01-01

While much previous work with highly charged ions has been performed with the ions in the plasma state in which they were formed, beams of highly charged ions hold promise for exciting new experiments. Specifically low energy beams with a high degree of charge state purity are a prerequisite for momentum resolved cross section measurements and for efficient loading of highly charged ions into UHV traps for spectroscopy. The Clemson University facility is optimized for the delivery of such beams of highly charged ions with low kinetic energies. Near term experiments include energy resolved charge exchange with neutral targets.

Plasmon mode excitation and photoluminescence enhancement on silver nanoring

NASA Astrophysics Data System (ADS)

Kuchmizhak, Aleksandr A.; Gurbatov, Stanislav O.; Kulchin, Yuri N.; Vitrik, Oleg B.

2015-12-01

We demonstrate a simple and high-performance laser-assisted technique for silver nanoring fabrication, which includes the ablation of the Ag film by focused nanosecond pulses and subsequent reactive ion polishing. The nanoring diameter and thickness can be controlled by optimizing both the pulse energy and the metal film thickness at laser ablation step, while the subsequent reactive ion polishing provides the ability to fabricate the nanoring with desirable height. Scattering patterns of s-polarized collimated laser beam obliquely illuminating the nanoring demonstrate the focal spot inside the nanoring shifted from its center at a distance of ~0.57Rring. Five-fold enhancement of the photoluminescence signal from the Rhodamine 6G organic dye near the Ag nanoring was demonstrated. This enhancement was attributed to the increase of the electromagnetic field amplitude near the nanoring surface arising from excitation of the multipole plasmon modes traveling along the nanoring. This assumption was confirmed by dark-field back-scattering spectrum of the nanoring measured under white-light illumination, as well as by supporting finite-difference time-domain simulations.

Nanopore fabrication and characterization by helium ion microscopy

NASA Astrophysics Data System (ADS)

Emmrich, D.; Beyer, A.; Nadzeyka, A.; Bauerdick, S.; Meyer, J. C.; Kotakoski, J.; Gölzhäuser, A.

2016-04-01

The Helium Ion Microscope (HIM) has the capability to image small features with a resolution down to 0.35 nm due to its highly focused gas field ionization source and its small beam-sample interaction volume. In this work, the focused helium ion beam of a HIM is utilized to create nanopores with diameters down to 1.3 nm. It will be demonstrated that nanopores can be milled into silicon nitride, carbon nanomembranes, and graphene with well-defined aspect ratio. To image and characterize the produced nanopores, helium ion microscopy and high resolution scanning transmission electron microscopy were used. The analysis of the nanopores' growth behavior allows inferring on the profile of the helium ion beam.

Thin films as a platform for understanding the conversion mechanism of FeF2 cathodes in lithium-ion microbatteries

NASA Astrophysics Data System (ADS)

Santos-Ortiz, Reinaldo

Conversion material electrodes such as FeF2 possess the potential to deliver transformative improvements in lithium ion battery performance because they permit a reversible change of more than one Li-ion per 3d metal cation. They outperform current state of the art intercalation cathodes such as LiCoO2, which have volumetric and gravimetric energy densities that are intrinsically limited by single electron transfer. Current studies focus on composite electrodes that are formed by mixing with carbon (FeF 2-C), wherein the carbon is expected to act as a binder to support the matrix and facilitate electronic conduction. These binders complicate the understanding of the electrode-electrolyte interface (SEI) passivation layer growth, of Li agglomeration, of ion and electron transport, and of the basic phase transformation processes under electrochemical cycling. This research uses thin-films as a model platform for obtaining basic understanding to the structural and chemical foundations of the phase conversion processes. Thin film cathodes are free of the binders used in nanocomposite structures and may potentially provide direct basic insight to the evolution of the SEI passivation layer, electron and ion transport, and the electrochemical behavior of true complex phases. The present work consisted of three main tasks (1) Development of optimized processes to deposit FeF2 and LiPON thin-films with the required phase purity and microstructure; (2) Understanding their electron and ion transport properties and; (3) Obtaining insight to the correlation between structure and capacity in thin-film microbatteries with FeF2 thin-film cathode and LiPON thin-film solid electrolyte. Optimized pulsed laser deposition (PLD) growth produced polycrystalline FeF2 films with excellent phase purity and P42/mnm crystallographic symmetry. A schematic band diagram was deduced using a combination of UPS, XPS and UV-Vis spectroscopies. Room temperature Hall measurements reveal that as-deposited FeF2 is n-type with an electron mobility of 0.33 cm 2/V.s and a resistivity was 0.255 O.cm. The LiPON films were deposited by reactive sputtering in nitrogen, and the results indicate that the ionic conductivity is dependent on the amount of nitrogen incorporated into the film during processing. The highest ionic conductivity obtained was 1.431.9E-6 Scm-1 and corresponded to a chemical composition of Li1.9PO3.3N.21.

Space Radiation Transport Code Development: 3DHZETRN

NASA Technical Reports Server (NTRS)

Wilson, John W.; Slaba, Tony C.; Badavi, Francis F.; Reddell, Brandon D.; Bahadori, Amir A.

2015-01-01

The space radiation transport code, HZETRN, has been used extensively for research, vehicle design optimization, risk analysis, and related applications. One of the simplifying features of the HZETRN transport formalism is the straight-ahead approximation, wherein all particles are assumed to travel along a common axis. This reduces the governing equation to one spatial dimension allowing enormous simplification and highly efficient computational procedures to be implemented. Despite the physical simplifications, the HZETRN code is widely used for space applications and has been found to agree well with fully 3D Monte Carlo simulations in many circumstances. Recent work has focused on the development of 3D transport corrections for neutrons and light ions (Z < 2) for which the straight-ahead approximation is known to be less accurate. Within the development of 3D corrections, well-defined convergence criteria have been considered, allowing approximation errors at each stage in model development to be quantified. The present level of development assumes the neutron cross sections have an isotropic component treated within N explicit angular directions and a forward component represented by the straight-ahead approximation. The N = 1 solution refers to the straight-ahead treatment, while N = 2 represents the bi-directional model in current use for engineering design. The figure below shows neutrons, protons, and alphas for various values of N at locations in an aluminum sphere exposed to a solar particle event (SPE) spectrum. The neutron fluence converges quickly in simple geometry with N > 14 directions. The improved code, 3DHZETRN, transports neutrons, light ions, and heavy ions under space-like boundary conditions through general geometry while maintaining a high degree of computational efficiency. A brief overview of the 3D transport formalism for neutrons and light ions is given, and extensive benchmarking results with the Monte Carlo codes Geant4, FLUKA, and PHITS are provided for a variety of boundary conditions and geometries. Improvements provided by the 3D corrections are made clear in the comparisons. Developments needed to connect 3DHZETRN to vehicle design and optimization studies will be discussed. Future theoretical development will relax the forward plus isotropic interaction assumption to more general angular dependence.

Electron density profile measurements at a self-focusing ion beam with high current density and low energy extracted through concave electrodes.

PubMed

Fujiwara, Y; Hirano, Y; Kiyama, S; Nakamiya, A; Koguchi, H; Sakakita, H

2014-02-01

The self-focusing phenomenon has been observed in a high current density and low energy ion beam. In order to study the mechanism of this phenomenon, a special designed double probe to measure the electron density and temperature is installed into the chamber where the high current density ion beam is injected. Electron density profile is successfully measured without the influence of the ion beam components. Estimated electron temperature and density are ∼0.9 eV and ∼8 × 10(8) cm(-3) at the center of ion beam cross section, respectively. It was found that a large amount of electrons are spontaneously accumulated in the ion beam line in the case of self-forcing state.

Invited review article: the electrostatic plasma lens.

PubMed

Goncharov, Alexey

2013-02-01

The fundamental principles, experimental results, and potential applications of the electrostatic plasma lens for focusing and manipulating high-current, energetic, heavy ion beams are reviewed. First described almost 50 years ago, this optical beam device provides space charge neutralization of the ion beam within the lens volume, and thus provides an effective and unique tool for focusing high current beams where a high degree of neutralization is essential to prevent beam blow-up. Short and long lenses have been explored, and a lens in which the magnetic field is provided by rare-earth permanent magnets has been demonstrated. Applications include the use of this kind of optical tool for laboratory ion beam manipulation, high dose ion implantation, heavy ion accelerator injection, in heavy ion fusion, and other high technology.

Assignment of the Stereochemistry and Anomeric Configuration of Sugars within Oligosaccharides Via Overlapping Disaccharide Ladders Using MSn

NASA Astrophysics Data System (ADS)

Konda, Chiharu; Londry, Frank A.; Bendiak, Brad; Xia, Yu

2014-08-01

A systematic approach is described that can pinpoint the stereo-structures (sugar identity, anomeric configuration, and location) of individual sugar units within linear oligosaccharides. Using a highly modified mass spectrometer, dissociation of linear oligosaccharides in the gas phase was optimized along multiple-stage tandem dissociation pathways (MSn, n = 4 or 5). The instrument was a hybrid triple quadrupole/linear ion trap mass spectrometer capable of high-efficiency bidirectional ion transfer between quadrupole arrays. Different types of collision-induced dissociation (CID), either on-resonance ion trap or beam-type CID could be utilized at any given stage of dissociation, enabling either glycosidic bond cleavages or cross-ring cleavages to be maximized when wanted. The approach first involves optimizing the isolation of disaccharide units as an ordered set of overlapping substructures via glycosidic bond cleavages during early stages of MSn, with explicit intent to minimize cross-ring cleavages. Subsequently, cross-ring cleavages were optimized for individual disaccharides to yield key diagnostic product ions ( m/ z 221). Finally, fingerprint patterns that establish stereochemistry and anomeric configuration were obtained from the diagnostic ions via CID. Model linear oligosaccharides were derivatized at the reducing end, allowing overlapping ladders of disaccharides to be isolated from MSn. High confidence stereo-structural determination was achieved by matching MSn CID of the diagnostic ions to synthetic standards via a spectral matching algorithm. Using this MSn ( n = 4 or 5) approach, the stereo-structures, anomeric configurations, and locations of three individual sugar units within two pentasaccharides were successfully determined.

Bioelectrochemical systems-driven directional ion transport enables low-energy water desalination, pollutant removal, and resource recovery.

PubMed

Chen, Xi; Liang, Peng; Zhang, Xiaoyuan; Huang, Xia

2016-09-01

Bioelectrochemical systems (BESs) are integrated water treatment technologies that generate electricity using organic matter in wastewater. In situ use of bioelectricity can direct the migration of ionic substances in a BES, thereby enabling water desalination, resource recovery, and valuable substance production. Recently, much attention has been placed on the microbial desalination cells in BESs to drive water desalination, and various configurations have optimized electricity generation and desalination performance and also coupled hydrogen production, heavy metal reduction, and other reactions. In addition, directional transport of other types of charged ions can remediate polluted groundwater, recover nutrient, and produce valuable substances. To better promote the practical application, the use of BESs as directional drivers of ionic substances requires further optimization to improve energy use efficiency and treatment efficacy. This article reviews existing researches on BES-driven directional ion transport to treat wastewater and identifies a few key factors involved in efficiency optimization. Copyright © 2016 Elsevier Ltd. All rights reserved.

Beam production of a laser ion source with a rotating hollow cylinder target for low energy positive and negative ions

NASA Astrophysics Data System (ADS)

Saquilayan, G. Q.; Wada, M.

2017-08-01

A laser ion source that utilizes a hollow cylinder target is being developed for the production of positive and negative ions. Continuous operation of the laser ion source is possible through the design of a rotating target. Ion extraction through a grounded circular aperture was tested for positive and negative ions up to 1 kV. Time-of-flight measurements for the mass separation of ions were made by placing a Faraday cup at locations 0 and 15 mm from the beam extraction axis. Signals corresponding to slow and massive ions were detected with mass at least 380 amu. Investigation on the beam profile suggests a geometrical optimization of the beam forming system is necessary.

Optimizing ion channel models using a parallel genetic algorithm on graphical processors.

PubMed

Ben-Shalom, Roy; Aviv, Amit; Razon, Benjamin; Korngreen, Alon

2012-01-01

We have recently shown that we can semi-automatically constrain models of voltage-gated ion channels by combining a stochastic search algorithm with ionic currents measured using multiple voltage-clamp protocols. Although numerically successful, this approach is highly demanding computationally, with optimization on a high performance Linux cluster typically lasting several days. To solve this computational bottleneck we converted our optimization algorithm for work on a graphical processing unit (GPU) using NVIDIA's CUDA. Parallelizing the process on a Fermi graphic computing engine from NVIDIA increased the speed ∼180 times over an application running on an 80 node Linux cluster, considerably reducing simulation times. This application allows users to optimize models for ion channel kinetics on a single, inexpensive, desktop "super computer," greatly reducing the time and cost of building models relevant to neuronal physiology. We also demonstrate that the point of algorithm parallelization is crucial to its performance. We substantially reduced computing time by solving the ODEs (Ordinary Differential Equations) so as to massively reduce memory transfers to and from the GPU. This approach may be applied to speed up other data intensive applications requiring iterative solutions of ODEs. Copyright © 2012 Elsevier B.V. All rights reserved.

Recent optimization of the beam-optical characteristics of the 6 MV van de Graaff accelerator for high brightness beams at the iThemba LABS NMP facility

NASA Astrophysics Data System (ADS)

Conradie, J. L.; Eisa, M. E. M.; Celliers, P. J.; Delsink, J. L. G.; Fourie, D. T.; de Villiers, J. G.; Maine, P. M.; Springhorn, K. A.; Pineda-Vargas, C. A.

2005-04-01

With the aim of improving the reliability and stability of the beams delivered to the nuclear microprobe at iThemba LABS, as well as optimization of the beam characteristics along the van de Graaff accelerator beamlines in general, relevant modifications were implemented since the beginning of 2003. The design and layout of the beamlines were revised. The beam-optical characteristics through the accelerator, from the ion source up to the analysing magnet directly after the accelerator, were calculated and the design optimised, using the computer codes TRANSPORT, IGUN and TOSCA. The ion source characteristics and optimal operating conditions were determined on an ion source test bench. The measured optimal emittance for 90% of the beam intensity was about 50π mm mrad for an extraction voltage of 6 kV. These changes allow operation of the Nuclear Microprobe at proton energies in the range 1 MeV-4 MeV with beam intensities of tenths of a pA at the target surface. The capabilities of the nuclear microprobe facility were evaluated in the improved beamline, with particular emphasis to bio-medical samples.

Focused ion beam micromilling and articles therefrom

DOEpatents

Lamartine, Bruce C.; Stutz, Roger A.

1998-01-01

An ultrahigh vacuum focused ion beam micromilling apparatus and process are isclosed. Additionally, a durable data storage medium using the micromilling process is disclosed, the durable data storage medium capable of storing, e.g., digital or alphanumeric characters as well as graphical shapes or characters.

Fast separation of two trapped ions (Open Access, Publisher’s Version)

DTIC Science & Technology

2015-09-17

of quantum states and separation of ions in a dual rf ion trapQuantum Inf. Comput . 2 257 [10] KaufmannH, Ruster T, SchmiegelowCT, Schmidt-Kaler F...Ruschhaupt et al. Shortcuts to adiabaticity for an ion in a rotating radially-tight trap M Palmero, Shuo Wang, D Guéry-Odelin et al. Optimal shortcuts for...Kiely, J P L McGuinness, J G Muga et al. Quantum simulations with cold trapped ions Michael Johanning, Andrés F Varón and Christof Wunderlich Quantum

Modeling of steady-state convective cooling of cylindrical Li-ion cells

NASA Astrophysics Data System (ADS)

Shah, K.; Drake, S. J.; Wetz, D. A.; Ostanek, J. K.; Miller, S. P.; Heinzel, J. M.; Jain, A.

2014-07-01

While Lithium-ion batteries have the potential to serve as an excellent means of energy storage, they suffer from several operational safety concerns. Temperature excursion beyond a specified limit for a Lithium-ion battery triggers a sequence of decomposition and release, which can preclude thermal runaway events and catastrophic failure. To optimize liquid or air-based convective cooling approaches, it is important to accurately model the thermal response of Lithium-ion cells to convective cooling, particularly in high-rate discharge applications where significant heat generation is expected. This paper presents closed-form analytical solutions for the steady-state temperature profile in a convectively cooled cylindrical Lithium-ion cell. These models account for the strongly anisotropic thermal conductivity of cylindrical Lithium-ion batteries due to the spirally wound electrode assembly. Model results are in excellent agreement with experimentally measured temperature rise in a thermal test cell. Results indicate that improvements in radial thermal conductivity and axial convective heat transfer coefficient may result in significant peak temperature reduction. Battery sizing optimization using the analytical model is discussed, indicating the dependence of thermal performance of the cell on its size and aspect ratio. Results presented in this paper may aid in accurate thermal design and thermal management of Lithium-ion batteries.

The 2nd order focusing sector field type TOF mass analyzer with an orthogonal ion acceleration for LC-IMS-MS.

PubMed

Poteshin, S S; Zarakovsky, A I

2017-03-15

Original orthogonal acceleration (OA) electrostatic sector time of flight (TOF) mass analyzer is proposed those allows the second order focusing of time of flight by initial ions position. Resolving power aberration limit exceeding 80,000 FW (full width mass peak) was shown to be obtainable for mass analyzer with the total length of flight L=133.2cm, the average ion energy 3700V and the ion energy spread of 2.5% on the entrance of sector field. Copyright © 2016 Elsevier B.V. All rights reserved.

Ion beam accelerator system

NASA Technical Reports Server (NTRS)

Aston, Graeme (Inventor)

1984-01-01

A system is described that combines geometrical and electrostatic focusing to provide high ion extraction efficiency and good focusing of an accelerated ion beam. The apparatus includes a pair of curved extraction grids (16, 18) with multiple pairs of aligned holes positioned to direct a group of beamlets (20) along converging paths. The extraction grids are closely spaced and maintained at a moderate potential to efficiently extract beamlets of ions and allow them to combine into a single beam (14). An accelerator electrode device (22) downstream from the extraction grids, is at a much lower potential than the grids to accelerate the combined beam.

Study of the Anatomy of the X-Ray and Neutron Production Scaling Laws in the Plasma Focus.

DTIC Science & Technology

1980-05-15

plasma focus discharge in deuterium as an extension of our previous work on scaling laws of x-ray and neutron production. The structure of dense plasmoids which emit MeV ions has been recorded by ion imaging with pinhole camera and contact print techniques. The plasmoids are generated in the same region in which particle beams, neutron and x-ray emission reach a maximum of intensity. Sharply defined boundaries of the ion-beam source and of plasmoids have been obtained by ion track etching on plastic material

Electrochemical model based charge optimization for lithium-ion batteries

NASA Astrophysics Data System (ADS)

Pramanik, Sourav; Anwar, Sohel

2016-05-01

In this paper, we propose the design of a novel optimal strategy for charging the lithium-ion battery based on electrochemical battery model that is aimed at improved performance. A performance index that aims at minimizing the charging effort along with a minimum deviation from the rated maximum thresholds for cell temperature and charging current has been defined. The method proposed in this paper aims at achieving a faster charging rate while maintaining safe limits for various battery parameters. Safe operation of the battery is achieved by including the battery bulk temperature as a control component in the performance index which is of critical importance for electric vehicles. Another important aspect of the performance objective proposed here is the efficiency of the algorithm that would allow higher charging rates without compromising the internal electrochemical kinetics of the battery which would prevent abusive conditions, thereby improving the long term durability. A more realistic model, based on battery electro-chemistry has been used for the design of the optimal algorithm as opposed to the conventional equivalent circuit models. To solve the optimization problem, Pontryagins principle has been used which is very effective for constrained optimization problems with both state and input constraints. Simulation results show that the proposed optimal charging algorithm is capable of shortening the charging time of a lithium ion cell while maintaining the temperature constraint when compared with the standard constant current charging. The designed method also maintains the internal states within limits that can avoid abusive operating conditions.

Cyanex based uranyl sensitive polymeric membrane electrodes.

PubMed

Badr, Ibrahim H A; Zidan, W I; Akl, Z F

2014-01-01

Novel uranyl selective polymeric membrane electrodes were prepared using three different low-cost and commercially available Cyanex extractants namely, bis(2,4,4-trimethylpentyl) phosphinic acid [L1], bis(2,4,4-trimethylpentyl) monothiophosphinic acid [L2] and bis(2,4,4-trimethylpentyl) dithiophosphinic acid [L3]. Optimization and performance characteristics of the developed Cyanex based polymer membrane electrodes were determined. The influence of membrane composition (e.g., amount and type of ionic sites, as well as type of plasticizer) on potentiometric responses of the prepared membrane electrodes was studied. Optimized Cyanex-based membrane electrodes exhibited Nernstian responses for UO₂(2+) ion over wide concentration ranges with fast response times. The optimized membrane electrodes based on L1, L2 and L3 exhibited Nernstian responses towards uranyl ion with slopes of 29.4, 28.0 and 29.3 mV decade(-1), respectively. The optimized membrane electrodes based on L1-L3 showed detection limits of 8.3 × 10(-5), 3.0 × 10(-5) and 3.3 × 10(-6) mol L(-1), respectively. The selectivity studies showed that the optimized membrane electrodes exhibited high selectivity towards UO₂(2+) ion over large number of other cations. Membrane electrodes based on L3 exhibited superior potentiometric response characteristics compared to those based on L1 and L2 (e.g., widest linear range and lowest detection limit). The analytical utility of uranyl membrane electrodes formulated with Cyanex extractant L3 was demonstrated by the analysis of uranyl ion in different real samples for nuclear safeguards verification purposes. The results obtained using direct potentiometry and flow-injection methods were compared with those measured using the standard UV-visible and inductively coupled plasma spectroscopic methods. © 2013 Published by Elsevier B.V.

The 25 mA continuous-wave surface-plasma source of H{sup −} ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belchenko, Yu., E-mail: belchenko@inp.nsk.su; Gorbovsky, A.; Sanin, A.

The ion source with the Penning geometry of electrodes producing continuous-wave beam of H{sup −} ions with current up to 25 mA was developed. Several improvements were introduced to increase source intensity, reliability, and lifetime. The collar around the emission aperture increases the electrons filtering. The apertures’ diameters of the ion-optical system electrodes were increased to generate the beam with higher intensity. An optimization of electrodes’ temperature was performed.

Lead Removal From Synthetic Leachate Matrices by a Novel Ion-Exchange Material

NASA Technical Reports Server (NTRS)

Street, Kenneth W., Jr.; Hovanitz, Edward S.; Chi, Sulan

2002-01-01

This report discusses the application of a novel polyacrylate-based ion-exchange material (IEM) for the removal of lead (Pb) ions from water. Preliminary testing includes the establishment of the operating pH range, capacity information, and the effect of calcium and anions in the matrix. Batch testing with powder indicates slightly different optimal operational conditions from those used for column testing. The ion exchanger is excellent for removing lead from aqueous solutions.

Demonstration of New, Highly Perchlorate-Selective Ion Exchange Resin Coupled with Resin-Optimized, Single-Vessel Engineering Design

DTIC Science & Technology

2013-03-01

effluent by ion chromatography (method described in Appendix A) Resin Separation Will remove >95% of fully exhausted resin (below mid-lateral...and retain >95% of the unexhausted resin (above the mid-lateral). 1) Mass balance on ClO4- during each cycle using ion chromatography and resin...Application Note 134, “Determination of Low Concentrations of Perchlorate in Drinking and Ground Waters Using Ion Chromatography ” and Product Note

Breakthrough in 4π ion emission mechanism understanding in plasma focus devices

PubMed Central

Sohrabi, Mehdi; Zarinshad, Arefe; Habibi, Morteza

2016-01-01

Ion emission angular distribution mechanisms in plasma focus devices (PFD) have not yet been well developed and understood being due to the lack of an efficient wide-angle ion distribution image detection system to characterize a PFD space in detail. Present belief is that the acceleration of ions points from “anode top” upwards in forward direction within a small solid angle. A breakthrough is reported in this study, by mega-size position-sensitive polycarbonate ion image detection systems invented, on discovery of 4π ion emission from the “anode top” in a PFD space after plasma pinch instability and radial run-away of ions from the “anode cathodes array” during axial acceleration of plasma sheaths before the radial phase. These two ion emission source mechanisms behave respectively as a “Point Ion Source” and a “Line Ion Source” forming “Ion Cathode Shadows” on mega-size detectors. We believe that the inventions and discoveries made here will open new horizons for advanced ion emission studies towards better mechanisms understanding and in particular will promote efficient applications of PFDs in medicine, science and technology. PMID:27941832

Improving the Molecular Ion Signal Intensity for In Situ Liquid SIMS Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Yufan; Yao, Juan; Ding, Yuanzhao

In situ liquid secondary ion mass spectrometry (SIMS) enabled by system for analysis at the liquid vacuum interface (SALVI) has proven to be a promising new tool to provide molecular information at solid–liquid and liquid–vacuum interfaces. However, the initial data showed that useful signals in positive ion spectra are too weak to be meaningful in most cases. In addition, it is difficult to obtain strong negative molecular ion signals when m/z>200. These two drawbacks have been the biggest obstacle towards practical use of this new analytical approach. In this study, we report that strong and reliable positive and negative molecularmore » signals are achievable after optimizing the SIMS experimental conditions. Four model systems, including a 1,8-diazabicycloundec-7-ene (DBU)-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte popularly used in Li ion batteries were studied. A signal enhancement of about two orders of magnitude was obtained in comparison with non-optimized conditions. Therefore, molecular ion signal intensity has become very acceptable to use for in situ liquid SIMS to study solid–liquid and liquid–vacuum interfaces.« less

Improving the Molecular Ion Signal Intensity for In Situ Liquid SIMS Analysis.

PubMed

Zhou, Yufan; Yao, Juan; Ding, Yuanzhao; Yu, Jiachao; Hua, Xin; Evans, James E; Yu, Xiaofei; Lao, David B; Heldebrant, David J; Nune, Satish K; Cao, Bin; Bowden, Mark E; Yu, Xiao-Ying; Wang, Xue-Lin; Zhu, Zihua

2016-12-01

In situ liquid secondary ion mass spectrometry (SIMS) enabled by system for analysis at the liquid vacuum interface (SALVI) has proven to be a promising new tool to provide molecular information at solid-liquid and liquid-vacuum interfaces. However, the initial data showed that useful signals in positive ion spectra are too weak to be meaningful in most cases. In addition, it is difficult to obtain strong negative molecular ion signals when m/z>200. These two drawbacks have been the biggest obstacle towards practical use of this new analytical approach. In this study, we report that strong and reliable positive and negative molecular signals are achievable after optimizing the SIMS experimental conditions. Four model systems, including a 1,8-diazabicycloundec-7-ene (DBU)-base switchable ionic liquid, a live Shewanella oneidensis biofilm, a hydrated mammalian epithelia cell, and an electrolyte popularly used in Li ion batteries were studied. A signal enhancement of about two orders of magnitude was obtained in comparison with non-optimized conditions. Therefore, molecular ion signal intensity has become very acceptable for use of in situ liquid SIMS to study solid-liquid and liquid-vacuum interfaces. Graphical Abstract ᅟ.

The effect of axial ion parameters on the properties of glow discharge polymer in T2B/H2 plasma

NASA Astrophysics Data System (ADS)

Ai, Xing; He, Xiao-Shan; Huang, Jing-Lin; He, Zhi-Bing; Du, Kai; Chen, Guo

2018-03-01

Glow discharge polymer (GDP) films were fabricated using plasma-enhanced chemical vapor deposition. The main purpose of this work was to explore the correlations of plasma parameters with the surface morphology and chemical structure of GDP films. The intensities of main positive ions and ion energy as functions of axial distances in T2B/H2 plasma were diagnosed using energy-resolved mass spectrometry. The surface morphology and chemical structure were characterized as functions of axial distances using a scanning electron microscope and Fourier transform infrared spectroscopy, respectively. As the axial distance increases, both the intensities of positive ions and high energy ions decreases, and dissociation weakens while polymerization enhances. This leads to the weakening of the cross-linking structure of GDP films and the formation of dome defects on films. Additionally, high energy ions could introduce a strong etching effect to form etching pits. Therefore, an axial distance of about 20 mm was found to be the optimal plasma parameter to prepare the defect-free GDP films. These results could help one to find the optimal plasma parameters for GDP film deposition.

Mass spectrometry detection and imaging of inorganic and organic explosive device signatures using desorption electro-flow focusing ionization.

PubMed

Forbes, Thomas P; Sisco, Edward

2014-08-05

We demonstrate the coupling of desorption electro-flow focusing ionization (DEFFI) with in-source collision induced dissociation (CID) for the mass spectrometric (MS) detection and imaging of explosive device components, including both inorganic and organic explosives and energetic materials. We utilize in-source CID to enhance ion collisions with atmospheric gas, thereby reducing adducts and minimizing organic contaminants. Optimization of the MS signal response as a function of in-source CID potential demonstrated contrasting trends for the detection of inorganic and organic explosive device components. DEFFI-MS and in-source CID enabled isotopic and molecular speciation of inorganic components, providing further physicochemical information. The developed system facilitated the direct detection and chemical mapping of trace analytes collected with Nomex swabs and spatially resolved distributions within artificial fingerprints from forensic lift tape. The results presented here provide the forensic and security sectors a powerful tool for the detection, chemical imaging, and inorganic speciation of explosives device signatures.

Favorable target positions for intense laser acceleration of electrons in hydrogen-like, highly-charged ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pi, Liang-Wen; Starace, Anthony F.; Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106-4030

2015-09-15

Classical relativistic Monte Carlo simulations of petawatt laser acceleration of electrons bound initially in hydrogen-like, highly-charged ions show that both the angles and energies of the laser-accelerated electrons depend on the initial ion positions with respect to the laser focus. Electrons bound in ions located after the laser focus generally acquire higher (≈GeV) energies and are ejected at smaller angles with respect to the laser beam. Our simulations assume a tightly-focused linearly-polarized laser pulse with intensity approaching 10{sup 22 }W/cm{sup 2}. Up to fifth order corrections to the paraxial approximation of the laser field in the focal region are taken intomore » account. In addition to the laser intensity, the Rayleigh length in the focal region is shown to play a significant role in maximizing the final energy of the accelerated electrons. Results are presented for both Ne{sup 9+} and Ar{sup 17+} target ions.« less

Ion acceleration in a plasma focus

NASA Technical Reports Server (NTRS)

Gary, S. P.

1974-01-01

The electric and magnetic fields associated with anomalous diffusion to the axis of a linear plasma discharge are used to compute representative ion trajectories. Substantial axial acceleration of the ions is demonstrated.

Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source.

PubMed

Pikin, A; Beebe, E N; Raparia, D

2013-03-01

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current up to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 ÷ 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 ÷ 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.

Simulation and optimization of a 10 A electron gun with electrostatic compression for the electron beam ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pikin, A.; Beebe, E. N.; Raparia, D.

Increasing the current density of the electron beam in the ion trap of the Electron Beam Ion Source (EBIS) in BNL's Relativistic Heavy Ion Collider facility would confer several essential benefits. They include increasing the ions' charge states, and therefore, the ions' energy out of the Booster for NASA applications, reducing the influx of residual ions in the ion trap, lowering the average power load on the electron collector, and possibly also reducing the emittance of the extracted ion beam. Here, we discuss our findings from a computer simulation of an electron gun with electrostatic compression for electron current upmore » to 10 A that can deliver a high-current-density electron beam for EBIS. The magnetic field in the cathode-anode gap is formed with a magnetic shield surrounding the gun electrodes and the residual magnetic field on the cathode is (5 Division-Sign 6) Gs. It was demonstrated that for optimized gun geometry within the electron beam current range of (0.5 Division-Sign 10) A the amplitude of radial beam oscillations can be maintained close to 4% of the beam radius by adjusting the injection magnetic field generated by a separate magnetic coil. Simulating the performance of the gun by varying geometrical parameters indicated that the original gun model is close to optimum and the requirements to the precision of positioning the gun elements can be easily met with conventional technology.« less

Ultrahigh vacuum focused ion beam micromill and articles therefrom

DOEpatents

Lamartine, Bruce C.; Stutz, Roger A.

1998-01-01

An ultrahigh vacuum focused ion beam micromilling apparatus and process are isclosed. Additionally, a durable data storage medium using the micromilling process is disclosed, the durable data storage medium capable of storing, e.g., digital or alphanumeric characters as well as graphical shapes or characters.

Focused ion beam micromilling and articles therefrom

DOEpatents

Lamartine, B.C.; Stutz, R.A.

1998-06-30

An ultrahigh vacuum focused ion beam micromilling apparatus and process are disclosed. Additionally, a durable data storage medium using the micromilling process is disclosed, the durable data storage medium capable of storing, e.g., digital or alphanumeric characters as well as graphical shapes or characters. 6 figs.

Full Monte Carlo-Based Biologic Treatment Plan Optimization System for Intensity Modulated Carbon Ion Therapy on Graphics Processing Unit.

PubMed

Qin, Nan; Shen, Chenyang; Tsai, Min-Yu; Pinto, Marco; Tian, Zhen; Dedes, Georgios; Pompos, Arnold; Jiang, Steve B; Parodi, Katia; Jia, Xun

2018-01-01

One of the major benefits of carbon ion therapy is enhanced biological effectiveness at the Bragg peak region. For intensity modulated carbon ion therapy (IMCT), it is desirable to use Monte Carlo (MC) methods to compute the properties of each pencil beam spot for treatment planning, because of their accuracy in modeling physics processes and estimating biological effects. We previously developed goCMC, a graphics processing unit (GPU)-oriented MC engine for carbon ion therapy. The purpose of the present study was to build a biological treatment plan optimization system using goCMC. The repair-misrepair-fixation model was implemented to compute the spatial distribution of linear-quadratic model parameters for each spot. A treatment plan optimization module was developed to minimize the difference between the prescribed and actual biological effect. We used a gradient-based algorithm to solve the optimization problem. The system was embedded in the Varian Eclipse treatment planning system under a client-server architecture to achieve a user-friendly planning environment. We tested the system with a 1-dimensional homogeneous water case and 3 3-dimensional patient cases. Our system generated treatment plans with biological spread-out Bragg peaks covering the targeted regions and sparing critical structures. Using 4 NVidia GTX 1080 GPUs, the total computation time, including spot simulation, optimization, and final dose calculation, was 0.6 hour for the prostate case (8282 spots), 0.2 hour for the pancreas case (3795 spots), and 0.3 hour for the brain case (6724 spots). The computation time was dominated by MC spot simulation. We built a biological treatment plan optimization system for IMCT that performs simulations using a fast MC engine, goCMC. To the best of our knowledge, this is the first time that full MC-based IMCT inverse planning has been achieved in a clinically viable time frame. Copyright © 2017 Elsevier Inc. All rights reserved.

Analysis of human serum proteins by liquid phase isoelectric focusing and matrix-assisted laser desorption/ionization-mass spectrometry.

PubMed

Wang, Michael Z; Howard, Brandon; Campa, Michael J; Patz, Edward F; Fitzgerald, Michael C

2003-09-01

Direct matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of human serum yielded ion signals from only a fraction of the total number of peptides and proteins expected to be in the sample. We increased the number of peptide and protein ion signals observed in the MALDI-TOF mass spectra analysis of human serum by using a prefractionation protocol based on liquid phase isoelectric focusing electrophoresis. This pre-fractionation technique facilitated the MALDI-TOF MS detection of as many as 262 different peptide and protein ion signals from human serum. The results obtained from three replicate fractionation experiments on the same serum sample indicated that 148 different peptide and protein ion signals were reproducibly detected using our isoelectric focusing and MALDI-TOF MS protocol.

Paul Ion Trap as a Diagnostic for Plasma Focus

NASA Astrophysics Data System (ADS)

Sadat Kiai, S. M.; Adlparvar, S.; Zirak, A.; Alhooie, Samira; Elahi, M.; Sheibani, S.; Safarien, A.; Farhangi, S.; Dabirzadeh, A. A.; Khalaj, M. M.; Mahlooji, M. S.; KaKaei, S.; Talaei, A.; Kashani, A.; Tajik Ahmadi, H.; Zahedi, F.

2010-02-01

The plasma discharge contamination by high and low Z Impurities affect the rate of nuclear fusion reaction products, specially when light particles have to be confined. These impurities should be analyzed and can be fairly controlled. This paper reports on the development of a Paul ion trap with ion sources by impact electron ionization as a diagnostic for the 10 kJ Iranian sunshine plasma focus device. Preliminary results of the residual gas are analyzed and presented.

Focused-ion-beam-inflicted surface amorphization and gallium implantation--new insights and removal by focused-electron-beam-induced etching.

PubMed

Roediger, P; Wanzenboeck, H D; Waid, S; Hochleitner, G; Bertagnolli, E

2011-06-10

Recently focused-electron-beam-induced etching of silicon using molecular chlorine (Cl(2)-FEBIE) has been developed as a reliable and reproducible process capable of damage-free, maskless and resistless removal of silicon. As any electron-beam-induced processing is considered non-destructive and implantation-free due to the absence of ion bombardment this approach is also a potential method for removing focused-ion-beam (FIB)-inflicted crystal damage and ion implantation. We show that Cl(2)-FEBIE is capable of removing FIB-induced amorphization and gallium ion implantation after processing of surfaces with a focused ion beam. TEM analysis proves that the method Cl(2)-FEBIE is non-destructive and therefore retains crystallinity. It is shown that Cl(2)-FEBIE of amorphous silicon when compared to crystalline silicon can be up to 25 times faster, depending on the degree of amorphization. Also, using this method it has become possible for the first time to directly investigate damage caused by FIB exposure in a top-down view utilizing a localized chemical reaction, i.e. without the need for TEM sample preparation. We show that gallium fluences above 4 × 10(15) cm(-2) result in altered material resulting from FIB-induced processes down to a depth of ∼ 250 nm. With increasing gallium fluences, due to a significant gallium concentration close beneath the surface, removal of the topmost layer by Cl(2)-FEBIE becomes difficult, indicating that gallium serves as an etch stop for Cl(2)-FEBIE.

Generation and focusing of pulsed intense ion beams: Final report, 1 July 1987--30 September 1988

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hammer, D.A.; Kusse, B.R.; Sudan, R.N.

1989-08-03

This paper discusses the following experiments: ion diode experiments at 0.5 /times/ 10/sup 12/ W on the LION accelerator; spectroscopic studies of ion diodes; ion beam-plasma channel transport research; and plasma opening switch experiments.

Design of high-energy high-current linac with focusing by superconducting solenoids

NASA Astrophysics Data System (ADS)

Batskikh, Guennady I.; Belugin, Vladimir M.; Bondarev, Boris I.; Fedotov, Arkady P.; Durkin, Alexander P.; Ivanov, Yury D.; Mikhailov, Vladimir N.; Murin, Boris P.; Mustafin, Kharis Kh.; Shumakov, Igor V.; Uksusov, Nikolay I.

1995-09-01

The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac is presented in the report. In new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channel features allow to decrease beam matched radius and increase a linac radiation purity without aperture growth. ``Regotron'' is used as high power generator in linac main part. But D&W cavities need not be divided into sections connected by RF-bridges which denuded them of high coupling factor.

Ion-beam apparatus and method for analyzing and controlling integrated circuits

DOEpatents

Campbell, A.N.; Soden, J.M.

1998-12-01

An ion-beam apparatus and method for analyzing and controlling integrated circuits are disclosed. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal. 4 figs.

Ion-beam apparatus and method for analyzing and controlling integrated circuits

DOEpatents

Campbell, Ann N.; Soden, Jerry M.

1998-01-01

An ion-beam apparatus and method for analyzing and controlling integrated circuits. The ion-beam apparatus comprises a stage for holding one or more integrated circuits (ICs); a source means for producing a focused ion beam; and a beam-directing means for directing the focused ion beam to irradiate a predetermined portion of the IC for sufficient time to provide an ion-beam-generated electrical input signal to a predetermined element of the IC. The apparatus and method have applications to failure analysis and developmental analysis of ICs and permit an alteration, control, or programming of logic states or device parameters within the IC either separate from or in combination with applied electrical stimulus to the IC for analysis thereof. Preferred embodiments of the present invention including a secondary particle detector and an electron floodgun further permit imaging of the IC by secondary ions or electrons, and allow at least a partial removal or erasure of the ion-beam-generated electrical input signal.

Production of highly charged heavy ions by 18 GHz superconducting electron cyclotron resonance at Research Center for Nuclear Physics.

PubMed

Yorita, Tetsuhiko; Hatanaka, Kichiji; Fukuda, Mitsuhiro; Kibayashi, Mitsuru; Morinobu, Shunpei; Okamura, Hiroyuki; Tamii, Atsushi

2010-02-01

An 18 GHz superconducting electron cyclotron resonance ion source has been installed as a subject of the azimuthally varying field cyclotron upgrade project (K. Hatanaka et al., in Proceedings of the 17th International Conference on Cyclotrons and Their Applications, Tokyo, Japan, 18-22 October 2004, pp. 115-117), in order to increase beam currents and to extend the variety of ions. The production development of several ions has been performed since 2006 and some of them have already been used for user experiments [T. Yorita et al., Rev. Sci. Instrum. 79, 02A311 (2008)]. Further optimizations for each component such as the material of plasma electrode, material, and shape of bias probe and mirror field have been continued and more intense ion beams have been obtained for O, N, and Ar. For the purpose of obtaining highly charged Xe with several microamperes, the optimization of position and shape of plasma electrode and bias disk has also been done and highly charged Xe(32+) beam has been obtained successfully.

Enhanced ion acceleration in transition from opaque to transparent plasmas

DOE PAGES

Mishra, R.; Fiuza, F.; Glenzer, S.

2018-04-20

Using particle-in-cell simulations, we investigate ion acceleration in the interaction of high intensity lasers with plasmas which transition from opaque to transparent during the interaction process. We show that the highest ion energies are achieved when the laser traverses the target around the peak intensity and re-heats the electron population responsible for the plasma expansion, enhancing the corresponding sheath electric field. This process can lead to an increase of up to 2x in ion energy when compared with the standard Target Normal Sheath Acceleration in opaque targets under the same laser conditions. A theoretical model is developed to predict themore » optimal target areal density as a function of laser intensity and pulse duration. A systematic parametric scan for a wide range of target densities and thicknesses is performed in 1D, 2D and 3D and shown consistent with the theory and with recent experimental results. Thus, these results open the way for a better optimization of the ion energy in future laser–solid experiments.« less

Enhanced ion acceleration in transition from opaque to transparent plasmas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mishra, R.; Fiuza, F.; Glenzer, S.

Using particle-in-cell simulations, we investigate ion acceleration in the interaction of high intensity lasers with plasmas which transition from opaque to transparent during the interaction process. We show that the highest ion energies are achieved when the laser traverses the target around the peak intensity and re-heats the electron population responsible for the plasma expansion, enhancing the corresponding sheath electric field. This process can lead to an increase of up to 2x in ion energy when compared with the standard Target Normal Sheath Acceleration in opaque targets under the same laser conditions. A theoretical model is developed to predict themore » optimal target areal density as a function of laser intensity and pulse duration. A systematic parametric scan for a wide range of target densities and thicknesses is performed in 1D, 2D and 3D and shown consistent with the theory and with recent experimental results. Thus, these results open the way for a better optimization of the ion energy in future laser–solid experiments.« less

First experimental-based characterization of oxygen ion beam depth dose distributions at the Heidelberg Ion-Beam Therapy Center

NASA Astrophysics Data System (ADS)

Kurz, C.; Mairani, A.; Parodi, K.

2012-08-01

Over the last decades, the application of proton and heavy-ion beams to external beam radiotherapy has rapidly increased. Due to the favourable lateral and depth dose profile, the superposition of narrow ion pencil beams may enable a highly conformal dose delivery to the tumour, with better sparing of the surrounding healthy tissue in comparison to conventional radiation therapy with photons. To fully exploit the promised clinical advantages of ion beams, an accurate planning of the patient treatments is required. The clinical treatment planning system (TPS) at the Heidelberg Ion-Beam Therapy Center (HIT) is based on a fast performing analytical algorithm for dose calculation, relying, among others, on laterally integrated depth dose distributions (DDDs) simulated with the FLUKA Monte Carlo (MC) code. Important input parameters of these simulations need to be derived from a comparison of the simulated DDDs with measurements. In this work, the first measurements of 16O ion DDDs at HIT are presented with a focus on the determined Bragg peak positions and the understanding of factors influencing the shape of the distributions. The measurements are compared to different simulation approaches aiming to reproduce the acquired data at best. A simplified geometrical model is first used to optimize important input parameters, not known a priori, in the simulations. This method is then compared to a more realistic, but also more time-consuming simulation approach better accounting for the experimental set-up and the measuring process. The results of this work contributed to a pre-clinical oxygen ion beam database, which is currently used by a research TPS for corresponding radio-biological cell experiments. A future extension to a clinical database used by the clinical TPS at HIT is foreseen. As a side effect, the performed investigations showed that the typical water equivalent calibration approach of experimental data acquired with water column systems leads to slight deviations between the experimentally determined and the real Bragg peak positions. For improved accuracy, the energy dependence of the stopping power, and herewith the water equivalent thickness, of the material downstream of the water tank should be considered in the analysis of measured data.

Ion kinematics in a plasma focus.

NASA Technical Reports Server (NTRS)

Gary, S. P.; Hohl, F.

1973-01-01

The results of numerical integrations of three-dimensional equations of motion of ions subject to given electric and magnetic fields are presented. The fields represent those which may exist in the pinch phase of the plasma focus, although here they depend only on the radial coordinate. The ions initially have Maxwellian velocity distributions, and their trajectories are interpreted in terms of single-particle constants of the motion. Two models of the axial electric field Ez are considered. For strong Ez away from the axis, there is a cyclotron acceleration which leads to ion heating. For positive Ez on the axis, ions within a Larmor radius of the axis undergo very efficient acceleration; the results for this new model are in general agreement with experimental results.

Fabrication and characterization of a co-planar detector in diamond for low energy single ion implantation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abraham, John Bishoy Sam; Pacheco, Jose L.; Aguirre, Brandon Adrian

2016-08-09

We demonstrate low energy single ion detection using a co-planar detector fabricated on a diamond substrate and characterized by ion beam induced charge collection. Histograms are taken with low fluence ion pulses illustrating quantized ion detection down to a single ion with a signal-to-noise ratio of approximately 10. We anticipate that this detection technique can serve as a basis to optimize the yield of single color centers in diamond. In conclusion, the ability to count ions into a diamond substrate is expected to reduce the uncertainty in the yield of color center formation by removing Poisson statistics from the implantationmore » process.« less

Ultrahigh vacuum focused ion beam micromill and articles therefrom

DOEpatents

Lamartine, B.C.; Stutz, R.A.

1998-02-24

An ultrahigh vacuum focused ion beam micromilling apparatus and process are disclosed. Additionally, a durable data storage medium using the micromilling process is disclosed, the durable data storage medium capable of storing, e.g., digital or alphanumeric characters as well as graphical shapes or characters. 6 figs.

Optimization of the multi-turn injection efficiency for a medical synchrotron

NASA Astrophysics Data System (ADS)

Kim, J.; Yoon, M.; Yim, H.

2016-09-01

We present a method for optimizing the multi-turn injection efficiency for a medical synchrotron. We show that for a given injection energy, the injection efficiency can be greatly enhanced by choosing transverse tunes appropriately and by optimizing the injection bump and the number of turns required for beam injection. We verify our study by applying the method to the Korea Heavy Ion Medical Accelerator (KHIMA) synchrotron which is currently being built at the campus of Dongnam Institute of Radiological and Medical Sciences (DIRAMS) in Busan, Korea. First the frequency map analysis was performed with the help of the ELEGANT and the ACCSIM codes. The tunes that yielded good injection efficiency were then selected. With these tunes, the injection bump and the number of turns required for injection were then optimized by tracking a number of particles for up to one thousand turns after injection, beyond which no further beam loss occurred. Results for the optimization of the injection efficiency for proton ions are presented.

The design of electron and ion guns, beams, and collectors

NASA Astrophysics Data System (ADS)

Becker, Reinard; Herrmannsfeldt, William B.

2004-01-01

The well known `SLAC Electron Trajectory Program' (EGUN) has been ported to PCs and has been developed into a family of programs for the design and the optimization of particle optics devices including electron and ion guns, beam transport sections and collectors. We will discuss the application of these tools for the design and the optimization of the essential parts of EBIS/T devices. The discussion will include conditions in which restrictions in the reliability of simulations may occur due to the mathematical modeling and how to overcome them.

Enhanced red emission of 808 nm excited upconversion nanoparticles by optimizing the composition of shell for efficient generation of singlet oxygen

NASA Astrophysics Data System (ADS)

Liu, Jinxue; Zhang, Tingbin; Song, Xiaoyan; Xing, Jinfeng

2018-01-01

With the aim to enhance the upconversion luminescence (UCL) intensity, much attention was paid to reduce the energy-back transfer from Er3+ ions to Nd3+ ions by constructing various kinds of multilayer upconversion nanoparticles (UCNPs). However, the energy-back transfer was difficult to be completely eliminated. Also, the thick shell of multilayer UCNPs is not favourable for effective Förster resonance energy transfer (FRET) in photodynamic therapy (PDT) system. Herein, an effective and facile method was applied to prepare UCNPs by optimizing the composition to largely enhance the red emission (at 660 nm) for efficient generation of singlet oxygen (1O2). In detail, the concentrations of Nd3+ ions and Yb3+ ions doped in the sensitizing shell were systematically researched to balance the energy back-transfer and the light harvest ability. The optimal emission and a relatively high Red/Green (R/G) ratio of NaYF4:Yb,Er,Nd@NaYF4:Yb0.1Nd0.2 UCNPs were obtained simultaneously. Furthermore, the emission under 980 nm excitation demonstrated the energy back-transfer from Er3+ to Yb3+ ions was also notable which was largely ignored previously. Then, UCNPs were encapsulated into mesoporous silica shell, and the photosensitizer Chlorin e6 (Ce6) was covalently conjugated to form a non-leaking nanoplatform. The efficiency of 1O2 generation obviously increased with the enhanced emission of UCNPs.

Isolation of metallothionein from cells derived from aggressive form of high-grade prostate carcinoma using paramagnetic antibody-modified microbeads off-line coupled with electrochemical and electrophoretic analysis.

PubMed

Masarik, Michal; Gumulec, Jaromir; Sztalmachova, Marketa; Hlavna, Marian; Babula, Petr; Krizkova, Sona; Ryvolova, Marketa; Jurajda, Michal; Sochor, Jiri; Adam, Vojtech; Kizek, Rene

2011-12-01

Prostate cancer with altered zinc(II) cell metabolism is the second most frequently diagnosed cancer in developed countries. The alterations of zinc(II) metabolism can influence metabolism of other metal ions and can also be associated with the expression and translation of metal-binding proteins including metallothioneins. The aim of this article was to optimize immunoseparation protocol based on paramagnetic beads conjugated with protein G for the isolation of metallothionein. Isolated metallothionein was determined by differential pulse voltammetry Brdicka reaction and SDS-PAGE. Optimal conditions: antigen-binding time - 60 min, temperature - 70°C, and buffer composition and pH - acetate buffer, pH 4.3, were determined. Under the optimized conditions, lysates from 22Rv1 prostate cancer cells treated with various concentrations of cadmium(II) and copper(II) ions were analyzed. We observed strong correlation in all experimental groups and all lysate types (r>0.83 at p<0.041) between metallothionein concentration related to viability and concentration of copper(II) ions and cadmium(II) ions in medium. Moreover, the results were compared with standard sample preparation as heat treatment and SDS-PAGE analysis. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Improvement of Vitamin K2 Production by Escherichia sp. with Nitrogen Ion Beam Implantation Induction

NASA Astrophysics Data System (ADS)

Liu, Yan; Wang, Li; Zheng, Zhiming; Wang, Peng; Zhao, Genhai; Liu, Hui; Gong, Guohong; Wu, Hefang; Liu, Hongxia; Tan, Mu; Li, Zhemin

2015-02-01

Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra. In this work, N+ ion beam implantation was used to enhance Escherichia sp. in vitamin K2 yield. Optimization of process parameters under submerged fermentation was carried out to improve the vitamin K2 yield of mutant FM5-632. The results indicate that an excellent mutant FM5-632 with a yield of 123.2±1.6 μg/L, that is four times that of the original strain, was achieved by eight successive implantations under the conditions of 15 keV and 60×2.6×1013 ions/cm2. A further optimization increased the yield of the mutant by 39.7%, i.e. 172.1±1.2 μg/L which occurred in the mutant cultivated in the optimal fermentation culture medium composed of (per liter): 15.31 g glycerol, 10 g peptone, 2.89 g yeast extract, 5 g K2HPO4, 1 g NaCl, 0.5 g MgSO4·7H2O and 0.04 g cedar wood oil, incubated at 33 °C, pH 7.0 and 180 rpm for 120 h.

Developments in the Material Fabrication and Performance of LiMn2O4 dCld Cathode Material

DTIC Science & Technology

2016-06-13

Lithium manganese spinel; Lithium rechargeable batteries , Lithium - ion battery ...requirements. Lithium and lithium - ion battery systems are highly sought after for rechargeable applications due to their high energy density (Wh/L...further optimization, the robust LixMn2O4-dCld spinel materials will be promising active materials for future integration into lithium - ion batteries

The ALICE experiment at the CERN LHC

NASA Astrophysics Data System (ADS)

ALICE Collaboration; Aamodt, K.; Abrahantes Quintana, A.; Achenbach, R.; Acounis, S.; Adamová, D.; Adler, C.; Aggarwal, M.; Agnese, F.; Aglieri Rinella, G.; Ahammed, Z.; Ahmad, A.; Ahmad, N.; Ahmad, S.; Akindinov, A.; Akishin, P.; Aleksandrov, D.; Alessandro, B.; Alfaro, R.; Alfarone, G.; Alici, A.; Alme, J.; Alt, T.; Altinpinar, S.; Amend, W.; Andrei, C.; Andres, Y.; Andronic, A.; Anelli, G.; Anfreville, M.; Angelov, V.; Anzo, A.; Anson, C.; Anticić, T.; Antonenko, V.; Antonczyk, D.; Antinori, F.; Antinori, S.; Antonioli, P.; Aphecetche, L.; Appelshäuser, H.; Aprodu, V.; Arba, M.; Arcelli, S.; Argentieri, A.; Armesto, N.; Arnaldi, R.; Arefiev, A.; Arsene, I.; Asryan, A.; Augustinus, A.; Awes, T. C.; Äysto, J.; Danish Azmi, M.; Bablock, S.; Badalà, A.; Badyal, S. K.; Baechler, J.; Bagnasco, S.; Bailhache, R.; Bala, R.; Baldisseri, A.; Baldit, A.; Bán, J.; Barbera, R.; Barberis, P.-L.; Barbet, J. M.; Barnäfoldi, G.; Barret, V.; Bartke, J.; Bartos, D.; Basile, M.; Basmanov, V.; Bastid, N.; Batigne, G.; Batyunya, B.; Baudot, J.; Baumann, C.; Bearden, I.; Becker, B.; Belikov, J.; Bellwied, R.; Belmont-Moreno, E.; Belogianni, A.; Belyaev, S.; Benato, A.; Beney, J. L.; Benhabib, L.; Benotto, F.; Beolé, S.; Berceanu, I.; Bercuci, A.; Berdermann, E.; Berdnikov, Y.; Bernard, C.; Berny, R.; Berst, J. D.; Bertelsen, H.; Betev, L.; Bhasin, A.; Baskar, P.; Bhati, A.; Bianchi, N.; Bielčik, J.; Bielčiková, J.; Bimbot, L.; Blanchard, G.; Blanco, F.; Blanco, F.; Blau, D.; Blume, C.; Blyth, S.; Boccioli, M.; Bogdanov, A.; Bøggild, H.; Bogolyubsky, M.; Boldizsár, L.; Bombara, M.; Bombonati, C.; Bondila, M.; Bonnet, D.; Bonvicini, V.; Borel, H.; Borotto, F.; Borshchov, V.; Bortoli, Y.; Borysov, O.; Bose, S.; Bosisio, L.; Botje, M.; Böttger, S.; Bourdaud, G.; Bourrion, O.; Bouvier, S.; Braem, A.; Braun, M.; Braun-Munzinger, P.; Bravina, L.; Bregant, M.; Bruckner, G.; Brun, R.; Bruna, E.; Brunasso, O.; Bruno, G. E.; Bucher, D.; Budilov, V.; Budnikov, D.; Buesching, H.; Buncic, P.; Burns, M.; Burachas, S.; Busch, O.; Bushop, J.; Cai, X.; Caines, H.; Calaon, F.; Caldogno, M.; Cali, I.; Camerini, P.; Campagnolo, R.; Campbell, M.; Cao, X.; Capitani, G. P.; Romeo, G. Cara; Cardenas-Montes, M.; Carduner, H.; Carena, F.; Carena, W.; Cariola, P.; Carminati, F.; Casado, J.; Casanova Diaz, A.; Caselle, M.; Castillo Castellanos, J.; Castor, J.; Catanescu, V.; Cattaruzza, E.; Cavazza, D.; Cerello, P.; Ceresa, S.; Černý, V.; Chambert, V.; Chapeland, S.; Charpy, A.; Charrier, D.; Chartoire, M.; Charvet, J. L.; Chattopadhyay, S.; Chattopadhyay, S.; Chepurnov, V.; Chernenko, S.; Cherney, M.; Cheshkov, C.; Cheynis, B.; Chochula, P.; Chiavassa, E.; Chibante Barroso, V.; Choi, J.; Christakoglou, P.; Christiansen, P.; Christensen, C.; Chykalov, O. A.; Cicalo, C.; Cifarelli-Strolin, L.; Ciobanu, M.; Cindolo, F.; Cirstoiu, C.; Clausse, O.; Cleymans, J.; Cobanoglu, O.; Coffin, J.-P.; Coli, S.; Colla, A.; Colledani, C.; Combaret, C.; Combet, M.; Comets, M.; Conesa Balbastre, G.; Conesa del Valle, Z.; Contin, G.; Contreras, J.; Cormier, T.; Corsi, F.; Cortese, P.; Costa, F.; Crescio, E.; Crochet, P.; Cuautle, E.; Cussonneau, J.; Dahlinger, M.; Dainese, A.; Dalsgaard, H. H.; Daniel, L.; Das, I.; Das, T.; Dash, A.; Da Silva, R.; Davenport, M.; Daues, H.; DeCaro, A.; de Cataldo, G.; DeCuveland, J.; DeFalco, A.; de Gaspari, M.; de Girolamo, P.; de Groot, J.; DeGruttola, D.; DeHaas, A.; DeMarco, N.; DePasquale, S.; DeRemigis, P.; de Vaux, D.; Decock, G.; Delagrange, H.; DelFranco, M.; Dellacasa, G.; Dell'Olio, C.; Dell'Olio, D.; Deloff, A.; Demanov, V.; Dénes, E.; D'Erasmo, G.; Derkach, D.; Devaux, A.; Di Bari, D.; Di Bartelomen, A.; Di Giglio, C.; Di Liberto, S.; Di Mauro, A.; Di Nezza, P.; Dialinas, M.; Diaz, L.; Díaz Valdes, R.; Dietel, T.; Dima, R.; Ding, H.; Dinca, C.; Divià, R.; Dobretsov, V.; Dobrin, A.; Doenigus, B.; Dobrowolski, T.; Domínguez, I.; Dorn, M.; Drouet, S.; Dubey, A. E.; Ducroux, L.; Dumitrache, F.; Dumonteil, E.; Dupieux, P.; Duta, V.; Dutta Majumdar, A.; Dutta Majumdar, M.; Dyhre, Th; Efimov, L.; Efremov, A.; Elia, D.; Emschermann, D.; Engster, C.; Enokizono, A.; Espagnon, B.; Estienne, M.; Evangelista, A.; Evans, D.; Evrard, S.; Fabjan, C. W.; Fabris, D.; Faivre, J.; Falchieri, D.; Fantoni, A.; Farano, R.; Fearick, R.; Fedorov, O.; Fekete, V.; Felea, D.; Feofilov, G.; Férnandez Téllez, A.; Ferretti, A.; Fichera, F.; Filchagin, S.; Filoni, E.; Finck, C.; Fini, R.; Fiore, E. M.; Flierl, D.; Floris, M.; Fodor, Z.; Foka, Y.; Fokin, S.; Force, P.; Formenti, F.; Fragiacomo, E.; Fragkiadakis, M.; Fraissard, D.; Franco, A.; Franco, M.; Frankenfeld, U.; Fratino, U.; Fresneau, S.; Frolov, A.; Fuchs, U.; Fujita, J.; Furget, C.; Furini, M.; Fusco Girard, M.; Gaardhøje, J.-J.; Gabrielli, A.; Gadrat, S.; Gagliardi, M.; Gago, A.; Gaido, L.; Gallas Torreira, A.; Gallio, M.; Gandolfi, E.; Ganoti, P.; Ganti, M.; Garabatos, J.; Garcia Lopez, A.; Garizzo, L.; Gaudichet, L.; Gemme, R.; Germain, M.; Gheata, A.; Gheata, M.; Ghidini, B.; Ghosh, P.; Giolu, G.; Giraudo, G.; Giubellino, P.; Glasow, R.; Glässel, P.; Ferreiro, E. G.; Gonzalez Gutierrez, C.; Gonzales-Trueba, L. H.; Gorbunov, S.; Gorbunov, Y.; Gos, H.; Gosset, J.; Gotovac, S.; Gottschlag, H.; Gottschalk, D.; Grabski, V.; Grassi, T.; Gray, H.; Grebenyuk, O.; Grebieszkow, K.; Gregory, C.; Grigoras, C.; Grion, N.; Grigoriev, V.; Grigoryan, A.; Grigoryan, C.; Grigoryan, S.; Grishuk, Y.; Gros, P.; Grosse-Oetringhaus, J.; Grossiord, J.-Y.; Grosso, R.; Grynyov, B.; Guarnaccia, C.; Guber, F.; Guerin, F.; Guernane, R.; Guerzoni, M.; Guichard, A.; Guida, M.; Guilloux, G.; Gulkanyan, H.; Gulbrandsen, K.; Gunji, T.; Gupta, A.; Gupta, V.; Gustafsson, H.-A.; Gutbrod, H.; Hadjidakis, C.; Haiduc, M.; Hamar, G.; Hamagaki, H.; Hamblen, J.; Hansen, J. C.; Hardy, P.; Hatzifotiadou, D.; Harris, J. W.; Hartig, M.; Harutyunyan, A.; Hayrapetyan, A.; Hasch, D.; Hasegan, D.; Hehner, J.; Heine, N.; Heinz, M.; Helstrup, H.; Herghelegiu, A.; Herlant, S.; Herrera Corral, G.; Herrmann, N.; Hetland, K.; Hille, P.; Hinke, H.; Hippolyte, B.; Hoch, M.; Hoebbel, H.; Hoedlmoser, H.; Horaguchi, T.; Horner, M.; Hristov, P.; Hřivnáčová, I.; Hu, S.; Guo, C. Hu; Humanic, T.; Hurtado, A.; Hwang, D. S.; Ianigro, J. C.; Idzik, M.; Igolkin, S.; Ilkaev, R.; Ilkiv, I.; Imhoff, M.; Innocenti, P. G.; Ionescu, E.; Ippolitov, M.; Irfan, M.; Insa, C.; Inuzuka, M.; Ivan, C.; Ivanov, A.; Ivanov, M.; Ivanov, V.; Jacobs, P.; Jacholkowski, A.; Jančurová, L.; Janik, R.; Jasper, M.; Jena, C.; Jirden, L.; Johnson, D. P.; Jones, G. T.; Jorgensen, C.; Jouve, F.; Jovanović, P.; Junique, A.; Jusko, A.; Jung, H.; Jung, W.; Kadija, K.; Kamal, A.; Kamermans, R.; Kapusta, S.; Kaidalov, A.; Kakoyan, V.; Kalcher, S.; Kang, E.; Kapitan, J.; Kaplin, V.; Karadzhev, K.; Karavichev, O.; Karavicheva, T.; Karpechev, E.; Karpio, K.; Kazantsev, A.; Kebschull, U.; Keidel, R.; Mohsin Khan, M.; Khanzadeev, A.; Kharlov, Y.; Kikola, D.; Kileng, B.; Kim, D.; Kim, D. S.; Kim, D. W.; Kim, H. N.; Kim, J. S.; Kim, S.; Kinson, J. B.; Kiprich, S. K.; Kisel, I.; Kiselev, S.; Kisiel, A.; Kiss, T.; Kiworra, V.; Klay, J.; Klein Bösing, C.; Kliemant, M.; Klimov, A.; Klovning, A.; Kluge, A.; Kluit, R.; Kniege, S.; Kolevatov, R.; Kollegger, T.; Kolojvari, A.; Kondratiev, V.; Kornas, E.; Koshurnikov, E.; Kotov, I.; Kour, R.; Kowalski, M.; Kox, S.; Kozlov, K.; Králik, I.; Kramer, F.; Kraus, I.; Kravčáková, A.; Krawutschke, T.; Krivda, M.; Kryshen, E.; Kucheriaev, Y.; Kugler, A.; Kuhn, C.; Kuijer, P.; Kumar, L.; Kumar, N.; Kumpumaeki, P.; Kurepin, A.; Kurepin, A. N.; Kushpil, S.; Kushpil, V.; Kutovsky, M.; Kvaerno, H.; Kweon, M.; Labbé, J.-C.; Lackner, F.; Ladron de Guevara, P.; Lafage, V.; La Rocca, P.; Lamont, M.; Lara, C.; Larsen, D. T.; Laurenti, G.; Lazzeroni, C.; LeBornec, Y.; LeBris, N.; LeGailliard, C.; Lebedev, V.; Lecoq, J.; Lee, K. S.; Lee, S. C.; Lefévre, F.; Legrand, I.; Lehmann, T.; Leistam, L.; Lenoir, P.; Lenti, V.; Leon, H.; Monzon, I. Leon; Lévai, P.; Li, Q.; Li, X.; Librizzi, F.; Lietava, R.; Lindegaard, N.; Lindenstruth, V.; Lippmann, C.; Lisa, M.; Listratenko, O. M.; Littel, F.; Liu, Y.; Lo, J.; Lobanov, V.; Loginov, V.; López Noriega, M.; López-Ramírez, R.; López Torres, E.; Lorenzo, P. M.; Løvhøiden, G.; Lu, S.; Ludolphs, W.; Lunardon, M.; Luquin, L.; Lusso, S.; Lutz, J.-R.; Luvisetto, M.; Lyapin, V.; Maevskaya, A.; Magureanu, C.; Mahajan, A.; Majahan, S.; Mahmoud, T.; Mairani, A.; Mahapatra, D.; Makarov, A.; Makhlyueva, I.; Malek, M.; Malkiewicz, T.; Mal'Kevich, D.; Malzacher, P.; Mamonov, A.; Manea, C.; Mangotra, L. K.; Maniero, D.; Manko, V.; Manso, F.; Manzari, V.; Mao, Y.; Marcel, A.; Marchini, S.; Mareš, J.; Margagliotti, G. V.; Margotti, A.; Marin, A.; Marin, J.-C.; Marras, D.; Martinengo, P.; Martínez, M. I.; Martinez-Davalos, A.; Martínez Garcia, G.; Martini, S.; Marzari Chiesa, A.; Marzocca, C.; Masciocchi, S.; Masera, M.; Masetti, M.; Maslov, N. I.; Masoni, A.; Massera, F.; Mast, M.; Mastroserio, A.; Matthews, Z. L.; Mayer, B.; Mazza, G.; Mazzaro, M. D.; Mazzoni, A.; Meddi, F.; Meleshko, E.; Menchaca-Rocha, A.; Meneghini, S.; Meoni, M.; Mercado Perez, J.; Mereu, P.; Meunier, O.; Miake, Y.; Michalon, A.; Michinelli, R.; Miftakhov, N.; Mignone, M.; Mikhailov, K.; Milosevic, J.; Minaev, Y.; Minafra, F.; Mischke, A.; Miśkowiec, D.; Mitsyn, V.; Mitu, C.; Mohanty, B.; Moisa, D.; Molnar, L.; Mondal, M.; Mondal, N.; Montaño Zetina, L.; Monteno, M.; Morando, M.; Morel, M.; Moretto, S.; Morhardt, Th; Morsch, A.; Moukhanova, T.; Mucchi, M.; Muccifora, V.; Mudnic, E.; Müller, H.; Müller, W.; Munoz, J.; Mura, D.; Musa, L.; Muraz, J. F.; Musso, A.; Nania, R.; Nandi, B.; Nappi, E.; Navach, F.; Navin, S.; Nayak, T.; Nazarenko, S.; Nazarov, G.; Nellen, L.; Nendaz, F.; Nianine, A.; Nicassio, M.; Nielsen, B. S.; Nikolaev, S.; Nikolic, V.; Nikulin, S.; Nikulin, V.; Nilsen, B.; Nitti, M.; Noferini, F.; Nomokonov, P.; Nooren, G.; Noto, F.; Nouais, D.; Nyiri, A.; Nystrand, J.; Odyniec, G.; Oeschler, H.; Oinonen, M.; Oldenburg, M.; Oleks, I.; Olsen, E. K.; Onuchin, V.; Oppedisano, C.; Orsini, F.; Ortiz-Velázquez, A.; Oskamp, C.; Oskarsson, A.; Osmic, F.; Österman, L.; Otterlund, I.; Ovrebekk, G.; Oyama, K.; Pachr, M.; Pagano, P.; Paić, G.; Pajares, C.; Pal, S.; Pal, S.; Pálla, G.; Palmeri, A.; Pancaldi, G.; Panse, R.; Pantaleo, A.; Pappalardo, G. S.; Pastirčák, B.; Pastore, C.; Patarakin, O.; Paticchio, V.; Patimo, G.; Pavlinov, A.; Pawlak, T.; Peitzmann, T.; Pénichot, Y.; Pepato, A.; Pereira, H.; Peresunko, D.; Perez, C.; Perez Griffo, J.; Perini, D.; Perrino, D.; Peryt, W.; Pesci, A.; Peskov, V.; Pestov, Y.; Peters, A. J.; Petráček, V.; Petridis, A.; Petris, M.; Petrov, V.; Petrov, V.; Petrovici, M.; Peyré, J.; Piano, S.; Piccotti, A.; Pichot, P.; Piemonte, C.; Pikna, M.; Pilastrini, R.; Pillot, P.; Pinazza, O.; Pini, B.; Pinsky, L.; Pinto Morais, V.; Pismennaya, V.; Piuz, F.; Platt, R.; Ploskon, M.; Plumeri, S.; Pluta, J.; Pocheptsov, T.; Podesta, P.; Poggio, F.; Poghosyan, M.; Poghosyan, T.; Polák, K.; Polichtchouk, B.; Polozov, P.; Polyakov, V.; Pommeresch, B.; Pompei, F.; Pop, A.; Popescu, S.; Posa, F.; Pospíšil, V.; Potukuchi, B.; Pouthas, J.; Prasad, S.; Preghenella, R.; Prino, F.; Prodan, L.; Prono, G.; Protsenko, M. A.; Pruneau, C. A.; Przybyla, A.; Pshenichnov, I.; Puddu, G.; Pujahari, P.; Pulvirenti, A.; Punin, A.; Punin, V.; Putschke, J.; Quartieri, J.; Quercigh, E.; Rachevskaya, I.; Rachevski, A.; Rademakers, A.; Radomski, S.; Radu, A.; Rak, J.; Ramello, L.; Raniwala, R.; Raniwala, S.; Rasmussen, O. B.; Rasson, J.; Razin, V.; Read, K.; Real, J.; Redlich, K.; Reichling, C.; Renard, C.; Renault, G.; Renfordt, R.; Reolon, A. R.; Reshetin, A.; Revol, J.-P.; Reygers, K.; Ricaud, H.; Riccati, L.; Ricci, R. A.; Richter, M.; Riedler, P.; Rigalleau, L. M.; Riggi, F.; Riegler, W.; Rindel, E.; Riso, J.; Rivetti, A.; Rizzi, M.; Rizzi, V.; Rodriguez Cahuantzi, M.; Røed, K.; Röhrich, D.; Román-López, S.; Romanato, M.; Romita, R.; Ronchetti, F.; Rosinsky, P.; Rosnet, P.; Rossegger, S.; Rossi, A.; Rostchin, V.; Rotondo, F.; Roukoutakis, F.; Rousseau, S.; Roy, C.; Roy, D.; Roy, P.; Royer, L.; Rubin, G.; Rubio, A.; Rui, R.; Rusanov, I.; Russo, G.; Ruuskanen, V.; Ryabinkin, E.; Rybicki, A.; Sadovsky, S.; Šafařík, K.; Sahoo, R.; Saini, J.; Saiz, P.; Salur, S.; Sambyal, S.; Samsonov, V.; Šándor, L.; Sandoval, A.; Sann, H.; Santiard, J.-C.; Santo, R.; Santoro, R.; Sargsyan, G.; Saturnini, P.; Scapparone, E.; Scarlassara, F.; Schackert, B.; Schiaua, C.; Schicker, R.; Schioler, T.; Schippers, J. D.; Schmidt, C.; Schmidt, H.; Schneider, R.; Schossmaier, K.; Schukraft, J.; Schutz, Y.; Schwarz, K.; Schweda, K.; Schyns, E.; Scioli, G.; Scomparin, E.; Snow, H.; Sedykh, S.; Segato, G.; Sellitto, S.; Semeria, F.; Senyukov, S.; Seppänen, H.; Serci, S.; Serkin, L.; Serra, S.; Sesselmann, T.; Sevcenco, A.; Sgura, I.; Shabratova, G.; Shahoyan, R.; Sharkov, E.; Sharma, S.; Shigaki, K.; Shileev, K.; Shukla, P.; Shurygin, A.; Shurygina, M.; Sibiriak, Y.; Siddi, E.; Siemiarczuk, T.; Sigward, M. H.; Silenzi, A.; Silvermyr, D.; Silvestri, R.; Simili, E.; Simion, V.; Simon, R.; Simonetti, L.; Singaraju, R.; Singhal, V.; Sinha, B.; Sinha, T.; Siska, M.; Sitár, B.; Sitta, M.; Skaali, B.; Skowronski, P.; Slodkowski, M.; Smirnov, N.; Smykov, L.; Snellings, R.; Snoeys, W.; Soegaard, C.; Soerensen, J.; Sokolov, O.; Soldatov, A.; Soloviev, A.; Soltveit, H.; Soltz, R.; Sommer, W.; Soos, C.; Soramel, F.; Sorensen, S.; Soyk, D.; Spyropoulou-Stassinaki, M.; Stachel, J.; Staley, F.; Stan, I.; Stavinskiy, A.; Steckert, J.; Stefanini, G.; Stefanek, G.; Steinbeck, T.; Stelzer, H.; Stenlund, E.; Stocco, D.; Stockmeier, M.; Stoicea, G.; Stolpovsky, P.; Strmeň, P.; Stutzmann, J. S.; Su, G.; Sugitate, T.; Šumbera, M.; Suire, C.; Susa, T.; Sushil Kumar, K.; Swoboda, D.; Symons, J.; Szarka, I.; Szostak, A.; Szuba, M.; Szymanski, P.; Tadel, M.; Tagridis, C.; Tan, L.; Tapia Takaki, D.; Taureg, H.; Tauro, A.; Tavlet, M.; Tejeda Munoz, G.; Thäder, J.; Tieulent, R.; Timmer, P.; Tolyhy, T.; Topilskaya, N.; Torcato de Matos, C.; Torii, H.; Toscano, L.; Tosello, F.; Tournaire, A.; Traczyk, T.; Tröger, G.; Tromeur, W.; Truesdale, D.; Trzaska, W.; Tsiledakis, G.; Tsilis, E.; Tsvetkov, A.; Turcato, M.; Turrisi, R.; Tuveri, M.; Tveter, T.; Tydesjo, H.; Tykarski, L.; Tywoniuk, K.; Ugolini, E.; Ullaland, K.; Urbán, J.; Urciuoli, G. M.; Usai, G. L.; Usseglio, M.; Vacchi, A.; Vala, M.; Valiev, F.; Vande Vyvre, P.; Van Den Brink, A.; Van Eijndhoven, N.; Van Der Kolk, N.; van Leeuwen, M.; Vannucci, L.; Vanzetto, S.; Vanuxem, J.-P.; Vargas, M. A.; Varma, R.; Vascotto, A.; Vasiliev, A.; Vassiliou, M.; Vasta, P.; Vechernin, V.; Venaruzzo, M.; Vercellin, E.; Vergara, S.; Verhoeven, W.; Veronese, F.; Vetlitskiy, I.; Vernet, R.; Victorov, V.; Vidak, L.; Viesti, G.; Vikhlyantsev, O.; Vilakazi, Z.; Villalobos Baillie, O.; Vinogradov, A.; Vinogradov, L.; Vinogradov, Y.; Virgili, T.; Viyogi, Y.; Vodopianov, A.; Volpe, G.; Vranic, D.; Vrláková, J.; Vulpescu, B.; Wabnitz, C.; Wagner, V.; Wallet, L.; Wan, R.; Wang, Y.; Wang, Y.; Wheadon, R.; Weis, R.; Wen, Q.; Wessels, J.; Westergaard, J.; Wiechula, J.; Wiesenaecker, A.; Wikne, J.; Wilk, A.; Wilk, G.; Williams, C.; Willis, N.; Windelband, B.; Witt, R.; Woehri, H.; Wyllie, K.; Xu, C.; Yang, C.; Yang, H.; Yermia, F.; Yin, Z.; Yin, Z.; Ky, B. Yun; Yushmanov, I.; Yuting, B.; Zabrodin, E.; Zagato, S.; Zagreev, B.; Zaharia, P.; Zalite, A.; Zampa, G.; Zampolli, C.; Zanevskiy, Y.; Zarochentsev, A.; Zaudtke, O.; Závada, P.; Zbroszczyk, H.; Zepeda, A.; Zeter, V.; Zgura, I.; Zhalov, M.; Zhou, D.; Zhou, S.; Zhu, G.; Zichichi, A.; Zinchenko, A.; Zinovjev, G.; Zoccarato, Y.; Zubarev, A.; Zucchini, A.; Zuffa, M.

2008-08-01

ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries. Its overall dimensions are 16 × 16 × 26 m3 with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.

Origins and mechanisms of hysteresis in organometal halide perovskites

NASA Astrophysics Data System (ADS)

Li, Cheng; Guerrero, Antonio; Zhong, Yu; Huettner, Sven

2017-05-01

Inorganic-organic halide organometal perovskites, such as CH3NH3PbI3 and CsPbI3, etc, have been an unprecedented rising star in the field of photovoltaics since 2009, owing to their exceptionally high power conversion efficiency and simple fabrication processability. Despite its relatively short history of development, intensive investigations have been concentrating on this material; these have ranged from crystal structure analysis and photophysical characterization to performance optimization and device integration, etc. Yet, when applied in photovoltaic devices, this material suffers from hysteresis, that is, the difference of the current-voltage (I-V) curve during sweeping in two directions (from short-circuit towards open-circuit and vice versa). This behavior may significantly impede its large-scale commercial application. This Review will focus on the recent theoretical and experimental efforts to reveal the origin and mechanism of hysteresis. The proposed origins include (1) ferroelectric polarization, (2) charge trapping/detrapping, and (3) ion migration. Among them, recent evidence consistently supports the idea that ion migration plays a key role for the hysteretic behavior in perovskite solar cells (PSCs). Hence, this Review will summarize the recent results on ion migration such as the migrating ion species, activation energy measurement, capacitive characterization, and internal electrical field modulation, etc. In addition, this Review will also present the devices with alleviation/elimination of hysteresis by incorporating either large-size grains or phenyl-C61-butyric acid methyl ester molecules. In a different application, the hysteretic property has been utilized in photovoltaic and memristive switching devices. In sum, by examining these three possible mechanisms, it is concluded that the origin of hysteresis in PSCs is associated with a combination of effects, but mainly limited by ion/defect migration. This strong interaction between ion motion and free charge carrier transport can be modulated by the prevalent crystalline structure, chemical passivation, and an external photo/electrical field.

ION COMPOSITION ELUCIDATION (ICE)

EPA Science Inventory

Ion Composition Elucidation (ICE) utilizes selected ion recording with a double focusing mass spectrometer to simultaneously determine exact masses and relative isotopic abundances from mass peak profiles. These can be determined more accurately and at higher sensitivity ...

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

NASA Astrophysics Data System (ADS)

Voronov, D. L.; Gawlitza, P.; Cambie, R.; Dhuey, S.; Gullikson, E. M.; Warwick, T.; Braun, S.; Yashchuk, V. V.; Padmore, H. A.

2012-05-01

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. To minimize the shadowing effects, we used an ion-beam sputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in order to minimize degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr+ ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voronov, D. L.; Cambie, R.; Dhuey, S.

2012-05-01

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. To minimize the shadowing effects, we used an ion-beam sputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in order to minimizemore » degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr{sup +} ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.« less

Conformal growth of Mo/Si multilayers on grating substrates using collimated ion beam sputtering

DOE Office of Scientific and Technical Information (OSTI.GOV)

Voronov, D. L.; Gawlitza, Peter; Cambie, Rossana

2012-05-07

Deposition of multilayers on saw-tooth substrates is a key step in the fabrication of multilayer blazed gratings (MBG) for extreme ultraviolet and soft x-rays. Growth of the multilayers can be perturbed by shadowing effects caused by the highly corrugated surface of the substrates, which results in distortion of the multilayer stack structure and degradation of performance of MBGs. In this study, to minimize the shadowing effects, we used an ion-beamsputtering machine with a highly collimated atomic flux to deposit Mo/Si multilayers on saw-tooth substrates. The sputtering conditions were optimized by finding a balance between smoothening and roughening processes in ordermore » to minimize degradation of the groove profile in the course of deposition and at the same time to keep the interfaces of a multilayer stack smooth enough for high efficiency. An optimal value of energy of 200 eV for sputtering Kr + ions was found by deposition of test multilayers on flat substrates at a range of ion energies. Two saw-tooth substrates were deposited at energies of 200 eV and 700 eV for the sputtering ions. It was found that reduction of the ion energy improved the blazing performance of the MBG and resulted in a 40% gain in the diffraction efficiency due to better replication of the groove profile by the multilayer. As a result of the optimization performed, an absolute diffraction efficiency of 28.8% was achieved for the 2nd blaze order of the MBG with a groove density of 7350 lines/mm at a wavelength of 13.5 nm. Lastly, details of the growth behavior of the multilayers on flat and saw-tooth substrates are discussed in terms of the linear continuous model of film growth.« less

Optimization of L(+)-Lactic Acid Production from Xylose with Rhizopus Oryzae Mutant RLC41-6 Breeding by Low-Energy Ion Implantation

NASA Astrophysics Data System (ADS)

Yang, Yingge; Fan, Yonghong; Li, Wen; Wang, Dongmei; Wu, Yuejin; Zheng, Zhiming; Yu, Zengliang

2007-10-01

In order to obtain an industrial strain with a higher L(+)-lactic acid yield, the strain Rhizopus oryzae PW352 was mutated by means of nitrogen ion beam implantation and the mutant strain Rhizopus oryzae RLC41-6 was obtained. An experimental finding was made in surprise that Rhizopus oryzae mutant RLC41-6 is not only an L(+)-lactic acid producer from corn starch but also an efficient producer of L(+)-lactic acid from xylose. Under optimal conditions, the production of L(+)-lactic acid from 100 g/L xylose reached 77.39 g/L after 144 h fed-batch fermentation. A high mutation rate and a wide mutation spectrum of low-energy ion implantation were observed in the experiment.

Recent progress in low-voltage cathodoluminescent materials: synthesis, improvement and emission properties.

PubMed

Li, Guogang; Lin, Jun

2014-01-01

Nowadays there are several technologies used for flat panel displays (FPDs) and the development of FPDs with enhanced energy efficiency and improved display quality is strongly required. Field emission displays (FEDs) have been considered as one of the most promising next generation flat panel display technologies due to their excellent display performance and low energy consumption. For the development of FEDs, phosphors are irreplaceable components. In the past decade, the study of highly efficient low-voltage cathodoluminescent materials, namely FED phosphors, has become the focus of enhancing energy efficiency and realizing high-quality displays. This review summaries the recent progress in the chemical synthesis and improvement of novel, rare-earth and transition metal ions activated inorganic cathodoluminescent materials in powder and thin film forms. The discussion is focused on the modification of morphology, size, surface, composition and conductivity of phosphors and the corresponding effects on their cathodoluminescent properties. Special emphases are given to the selection of host and luminescent centers, the adjustment of emission colors through doping concentration optimization, energy transfer and mono- or co-doping activator ions, the improvement of chromaticity, color stability and color gamut as well as the saturation behavior and the degradation behavior of phosphors under the excitation of a low-voltage electron beam. Finally, the research prospects and future directions of FED phosphors are discussed with recommendations to facilitate the further study of new and highly efficient low-voltage cathodoluminescent materials.

The modification at CSNS ion source

NASA Astrophysics Data System (ADS)

Liu, S.; Ouyang, H.; Huang, T.; Xiao, Y.; Cao, X.; Lv, Y.; Xue, K.; Chen, W.

2017-08-01

The commissioning of CSNS front end has been finished. Above 15 mA beam intensity is obtained at the end of RFQ. For CSNS ion source, it is a type of penning surface plasma ion source, similar to ISIS ion source. To improve the operation stability and reduce spark rate, some modifications have been performed, including Penning field, extraction optics and post acceleration. PBGUNS is applied to optimize beam extraction. The co-extraction electrons are considered at PBGUNS simulation and various extracted structure are simulated aiming to make the beam through the extracted electrode without loss. The stability of ion source is improved further.

Low pressure electrospray ionization system and process for effective transmission of ions

DOEpatents

Tang, Keqi [Richland, WA; Page, Jason S [Kennewick, WA; Kelly, Ryan T [Wet Richland, WA; Smith, Richard D [Richland, WA

2010-03-02

A system and method are disclosed that provide up to complete transmission of ions between coupled stages with low effective ion losses. A novel "interfaceless" electrospray ionization system is further described that operates the electrospray at a reduced pressure such that standard electrospray sample solutions can be directly sprayed into an electrodynamic ion funnel which provides ion focusing and transmission of ions into a mass analyzer.

Laser micromachined isoelectric focusing devices on polymer substrate for electrospray mass spectrometry

NASA Astrophysics Data System (ADS)

Lin, Yuehe; Wen, Jenny; Fan, Xiang; Matson, Dean W.; Smith, Richard D.

1999-08-01

A microfabricated device for isoelectric focusing (IEF) incorporating an optimized electrospray ionization (ESI) tip was constructed on polycarbonate plates using a laser micromachining technique. The separation channels on an IEF chip were 16 cm long, 50 micrometers wide and 30 micrometers deep. Electrical potentials used for IEF focusing and electrospray were applied through platinum electrodes placed in the buffer reservoirs, and which were isolated from the separation channel by molecular porous membranes. On-line ESI produced directly from a sharp `tip' on the microchip was evaluated. The results indicate that this design can produce a stable electrospray that is further improved and made more flexible with the assistance of sheath gas and sheath liquid. Error analysis of the spectral data shows that the standard deviation in signal intensity for an analyte peak was less than approximately 5% over 3 hours. The production of stable electrosprays directly from microchip IEF devices represents a step towards easily- fabricated microanalytical devices. IEF separations of protein mixtures were demonstrated for uncoated polycarbonate microchips. On-line IEF/ESI-MS was demonstrated using the microfabricated chip with an ion-trap ESI mass spectrometer for characterization of protein mixtures.

An electron cyclotron resonance ion source based low energy ion beam platform.

PubMed

Sun, L T; Shang, Y; Ma, B H; Zhang, X Z; Feng, Y C; Li, X X; Wang, H; Guo, X H; Song, M T; Zhao, H Y; Zhang, Z M; Zhao, H W; Xie, D Z

2008-02-01

To satisfy the requirements of surface and atomic physics study in the field of low energy multiple charge state ion incident experiments, a low energy (10 eV/q-20 keV/q) ion beam platform is under design at IMP. A simple test bench has been set up to test the ion beam deceleration systems. Considering virtues such as structure simplicity, easy handling, compactness, cost saving, etc., an all-permanent magnet ECRIS LAPECR1 [Lanzhou all-permanent magnet electron cyclotron resonance (ECR) ion source No. 1] working at 14.5 GHz has been adopted to produce intense medium and low charge state ion beams. LAPECR1 source has already been ignited. Some intense low charge state ion beams have been produced on it, but the first test also reveals that many problems are existing on the ion beam transmission line. The ion beam transmission mismatches result in the depressed performance of LAPECR1, which will be discussed in this paper. To obtain ultralow energy ion beam, after being analyzed by a double-focusing analyzer magnet, the selected ion beam will be further decelerated by two afocal deceleration lens systems, which is still under design. This design has taken into consideration both ions slowing down and also ion beam focusing. In this paper, the conceptual design of deceleration system will be discussed.

Rapid Adsorption of Heavy Metals by Fe3O4/Talc Nanocomposite and Optimization Study Using Response Surface Methodology

PubMed Central

Kalantari, Katayoon; Ahmad, Mansor B.; Masoumi, Hamid Reza Fard; Shameli, Kamyar; Basri, Mahiran; Khandanlou, Roshanak

2014-01-01

Fe3O4/talc nanocomposite was used for removal of Cu(II), Ni(II), and Pb(II) ions from aqueous solutions. Experiments were designed by response surface methodology (RSM) and a quadratic model was used to predict the variables. The adsorption parameters such as adsorbent dosage, removal time, and initial ion concentration were used as the independent variables and their effects on heavy metal ion removal were investigated. Analysis of variance was incorporated to judge the adequacy of the models. Optimal conditions with initial heavy metal ion concentration of 100, 92 and 270 mg/L, 120 s of removal time and 0.12 g of adsorbent amount resulted in 72.15%, 50.23%, and 91.35% removal efficiency for Cu(II), Ni(II), and Pb(II), respectively. The predictions of the model were in good agreement with experimental results and the Fe3O4/talc nanocomposite was successfully used to remove heavy metals from aqueous solutions. PMID:25050784

Finite element modeling simulation-assisted design of integrated microfluidic chips for heavy metal ion stripping analysis

NASA Astrophysics Data System (ADS)

Hong, Ying; Zou, Jianhua; Ge, Gang; Xiao, Wanyue; Gao, Ling; Shao, Jinjun; Dong, Xiaochen

2017-10-01

In this article, a transparent integrated microfluidic device composed of a 3D-printed thin-layer flow cell (3D-PTLFC) and an S-shaped screen-printed electrode (SPE) has been designed and fabricated for heavy metal ion stripping analysis. A finite element modeling (FEM) simulation is employed to optimize the shape of the electrode, the direction of the inlet pipeline, the thin-layer channel height and the sample flow rate to enhance the electron-enrichment efficiency for stripping analysis. The results demonstrate that the S-shaped SPE configuration matches the channel in 3D-PTLFC perfectly for the anodic stripping behavior of the heavy metal ions. Under optimized conditions, a wide linear range of 1-80 µg l-1 is achieved for Pb2+ detection with a limit of 0.3 µg l-1 for the microfluidic device. Thus, the obtained integrated microfluidic device proves to be a promising approach for heavy metal ions stripping analysis with low cost and high performance.

Rapid adsorption of heavy metals by Fe3O4/talc nanocomposite and optimization study using response surface methodology.

PubMed

Kalantari, Katayoon; Ahmad, Mansor B; Masoumi, Hamid Reza Fard; Shameli, Kamyar; Basri, Mahiran; Khandanlou, Roshanak

2014-07-21

Fe3O4/talc nanocomposite was used for removal of Cu(II), Ni(II), and Pb(II) ions from aqueous solutions. Experiments were designed by response surface methodology (RSM) and a quadratic model was used to predict the variables. The adsorption parameters such as adsorbent dosage, removal time, and initial ion concentration were used as the independent variables and their effects on heavy metal ion removal were investigated. Analysis of variance was incorporated to judge the adequacy of the models. Optimal conditions with initial heavy metal ion concentration of 100, 92 and 270 mg/L, 120 s of removal time and 0.12 g of adsorbent amount resulted in 72.15%, 50.23%, and 91.35% removal efficiency for Cu(II), Ni(II), and Pb(II), respectively. The predictions of the model were in good agreement with experimental results and the Fe3O4/talc nanocomposite was successfully used to remove heavy metals from aqueous solutions.

Molecular dynamics and dynamic Monte-Carlo simulation of irradiation damage with focused ion beams

NASA Astrophysics Data System (ADS)

Ohya, Kaoru

2017-03-01

The focused ion beam (FIB) has become an important tool for micro- and nanostructuring of samples such as milling, deposition and imaging. However, this leads to damage of the surface on the nanometer scale from implanted projectile ions and recoiled material atoms. It is therefore important to investigate each kind of damage quantitatively. We present a dynamic Monte-Carlo (MC) simulation code to simulate the morphological and compositional changes of a multilayered sample under ion irradiation and a molecular dynamics (MD) simulation code to simulate dose-dependent changes in the backscattering-ion (BSI)/secondary-electron (SE) yields of a crystalline sample. Recent progress in the codes for research to simulate the surface morphology and Mo/Si layers intermixing in an EUV lithography mask irradiated with FIBs, and the crystalline orientation effect on BSI and SE yields relating to the channeling contrast in scanning ion microscopes, is also presented.

Monte Carlo simulations of nanoscale focused neon ion beam sputtering.

PubMed

Timilsina, Rajendra; Rack, Philip D

2013-12-13

A Monte Carlo simulation is developed to model the physical sputtering of aluminum and tungsten emulating nanoscale focused helium and neon ion beam etching from the gas field ion microscope. Neon beams with different beam energies (0.5-30 keV) and a constant beam diameter (Gaussian with full-width-at-half-maximum of 1 nm) were simulated to elucidate the nanostructure evolution during the physical sputtering of nanoscale high aspect ratio features. The aspect ratio and sputter yield vary with the ion species and beam energy for a constant beam diameter and are related to the distribution of the nuclear energy loss. Neon ions have a larger sputter yield than the helium ions due to their larger mass and consequently larger nuclear energy loss relative to helium. Quantitative information such as the sputtering yields, the energy-dependent aspect ratios and resolution-limiting effects are discussed.

Model Based Optimal Control, Estimation, and Validation of Lithium-Ion Batteries

NASA Astrophysics Data System (ADS)

Perez, Hector Eduardo

This dissertation focuses on developing and experimentally validating model based control techniques to enhance the operation of lithium ion batteries, safely. An overview of the contributions to address the challenges that arise are provided below. Chapter 1: This chapter provides an introduction to battery fundamentals, models, and control and estimation techniques. Additionally, it provides motivation for the contributions of this dissertation. Chapter 2: This chapter examines reference governor (RG) methods for satisfying state constraints in Li-ion batteries. Mathematically, these constraints are formulated from a first principles electrochemical model. Consequently, the constraints explicitly model specific degradation mechanisms, such as lithium plating, lithium depletion, and overheating. This contrasts with the present paradigm of limiting measured voltage, current, and/or temperature. The critical challenges, however, are that (i) the electrochemical states evolve according to a system of nonlinear partial differential equations, and (ii) the states are not physically measurable. Assuming available state and parameter estimates, this chapter develops RGs for electrochemical battery models. The results demonstrate how electrochemical model state information can be utilized to ensure safe operation, while simultaneously enhancing energy capacity, power, and charge speeds in Li-ion batteries. Chapter 3: Complex multi-partial differential equation (PDE) electrochemical battery models are characterized by parameters that are often difficult to measure or identify. This parametric uncertainty influences the state estimates of electrochemical model-based observers for applications such as state-of-charge (SOC) estimation. This chapter develops two sensitivity-based interval observers that map bounded parameter uncertainty to state estimation intervals, within the context of electrochemical PDE models and SOC estimation. Theoretically, this chapter extends the notion of interval observers to PDE models using a sensitivity-based approach. Practically, this chapter quantifies the sensitivity of battery state estimates to parameter variations, enabling robust battery management schemes. The effectiveness of the proposed sensitivity-based interval observers is verified via a numerical study for the range of uncertain parameters. Chapter 4: This chapter seeks to derive insight on battery charging control using electrochemistry models. Directly using full order complex multi-partial differential equation (PDE) electrochemical battery models is difficult and sometimes impossible to implement. This chapter develops an approach for obtaining optimal charge control schemes, while ensuring safety through constraint satisfaction. An optimal charge control problem is mathematically formulated via a coupled reduced order electrochemical-thermal model which conserves key electrochemical and thermal state information. The Legendre-Gauss-Radau (LGR) pseudo-spectral method with adaptive multi-mesh-interval collocation is employed to solve the resulting nonlinear multi-state optimal control problem. Minimum time charge protocols are analyzed in detail subject to solid and electrolyte phase concentration constraints, as well as temperature constraints. The optimization scheme is examined using different input current bounds, and an insight on battery design for fast charging is provided. Experimental results are provided to compare the tradeoffs between an electrochemical-thermal model based optimal charge protocol and a traditional charge protocol. Chapter 5: Fast and safe charging protocols are crucial for enhancing the practicality of batteries, especially for mobile applications such as smartphones and electric vehicles. This chapter proposes an innovative approach to devising optimally health-conscious fast-safe charge protocols. A multi-objective optimal control problem is mathematically formulated via a coupled electro-thermal-aging battery model, where electrical and aging sub-models depend upon the core temperature captured by a two-state thermal sub-model. The Legendre-Gauss-Radau (LGR) pseudo-spectral method with adaptive multi-mesh-interval collocation is employed to solve the resulting highly nonlinear six-state optimal control problem. Charge time and health degradation are therefore optimally traded off, subject to both electrical and thermal constraints. Minimum-time, minimum-aging, and balanced charge scenarios are examined in detail. Sensitivities to the upper voltage bound, ambient temperature, and cooling convection resistance are investigated as well. Experimental results are provided to compare the tradeoffs between a balanced and traditional charge protocol. Chapter 6: This chapter provides concluding remarks on the findings of this dissertation and a discussion of future work.

Students' Understanding of External Representations of the Potassium Ion Channel Protein Part II: Structure-Function Relationships and Fragmented Knowledge

ERIC Educational Resources Information Center

Harle, Marissa; Towns, Marcy H.

2012-01-01

Research that has focused on external representations in biochemistry has uncovered student difficulties in comprehending and interpreting external representations. This study focuses on students' understanding of three external representations (ribbon diagram, wireframe, and hydrophobic/hydrophilic) of the potassium ion channel protein. Analysis…

High-throughput design and optimization of fast lithium ion conductors by the combination of bond-valence method and density functional theory

NASA Astrophysics Data System (ADS)

Xiao, Ruijuan; Li, Hong; Chen, Liquan

2015-09-01

Looking for solid state electrolytes with fast lithium ion conduction is an important prerequisite for developing all-solid-state lithium secondary batteries. By combining the simulation techniques in different levels of accuracy, e.g. the bond-valence (BV) method and the density functional theory (DFT), a high-throughput design and optimization scheme is proposed for searching fast lithium ion conductors as candidate solid state electrolytes for lithium rechargeable batteries. The screening from more than 1000 compounds is performed through BV-based method, and the ability to predict reliable tendency of the Li+ migration energy barriers is confirmed by comparing with the results from DFT calculations. β-Li3PS4 is taken as a model system to demonstrate the application of this combination method in optimizing properties of solid electrolytes. By employing the high-throughput DFT simulations to more than 200 structures of the doping derivatives of β-Li3PS4, the effects of doping on the ionic conductivities in this material are predicted by the BV calculations. The O-doping scheme is proposed as a promising way to improve the kinetic properties of this materials, and the validity of the optimization is proved by the first-principles molecular dynamics (FPMD) simulations.

Metal Ion Modeling Using Classical Mechanics

PubMed Central

2017-01-01

Metal ions play significant roles in numerous fields including chemistry, geochemistry, biochemistry, and materials science. With computational tools increasingly becoming important in chemical research, methods have emerged to effectively face the challenge of modeling metal ions in the gas, aqueous, and solid phases. Herein, we review both quantum and classical modeling strategies for metal ion-containing systems that have been developed over the past few decades. This Review focuses on classical metal ion modeling based on unpolarized models (including the nonbonded, bonded, cationic dummy atom, and combined models), polarizable models (e.g., the fluctuating charge, Drude oscillator, and the induced dipole models), the angular overlap model, and valence bond-based models. Quantum mechanical studies of metal ion-containing systems at the semiempirical, ab initio, and density functional levels of theory are reviewed as well with a particular focus on how these methods inform classical modeling efforts. Finally, conclusions and future prospects and directions are offered that will further enhance the classical modeling of metal ion-containing systems. PMID:28045509

Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

NASA Astrophysics Data System (ADS)

Sohrabi, M.; Habibi, M.; Ramezani, V.

2017-02-01

The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of 4.4 × 104 tracks/cm2 was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due to the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.

Two-dimensional particle-in-cell plasma source ion implantation of a prolate spheroid target

NASA Astrophysics Data System (ADS)

Liu, Cheng-Sen; Han, Hong-Ying; Peng, Xiao-Qing; Chang, Ye; Wang, De-Zhen

2010-03-01

A two-dimensional particle-in-cell simulation is used to study the time-dependent evolution of the sheath surrounding a prolate spheroid target during a high voltage pulse in plasma source ion implantation. Our study shows that the potential contour lines pack more closely in the plasma sheath near the vertex of the major axis, i.e. where a thinner sheath is formed, and a non-uniform total ion dose distribution is incident along the surface of the prolate spheroid target due to the focusing of ions by the potential structure. Ion focusing takes place not only at the vertex of the major axis, where dense potential contour lines exist, but also at the vertex of the minor axis, where sparse contour lines exist. This results in two peaks of the received ion dose, locating at the vertices of the major and minor axes of the prolate spheroid target, and an ion dose valley, staying always between the vertices, rather than at the vertex of the minor axis.

Interesting experimental results in Japan Proton Accelerator Research Complex H{sup -} ion-source development (invited)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ueno, A.; Oguri, H.; Ikegami, K.

2010-02-15

The following interesting experimental results observed in Japan Proton Accelerator Research Complex (J-PARC) H{sup -} ion-source developments are reviewed. It was proven that almost all of H{sup -} ions were produced with surface reactions in cesium (Cs)-free J-PARC H{sup -} ion-sources. The world's most intense class H{sup -} ion current of 38 mA in Cs-free ion sources for a high-energy linac was attained by an optimal shape and high temperature of the plasma electrode (PE), usage of a lanthanum hexaboride (LaB{sub 6}) filament, and a newly devised high-power constant-current pulsed-arc power supply indispensable for it. It was also proven thatmore » the H{sup -} ion current could be increased to more than 40 mA by optimizing LaB{sub 6}-filament shape. The surface elemental analysis of the PE after operation with a LaB{sub 6}-filament showed that it was coated by boron (B) 95.5%, lanthanum (La) 2.5%, and oxygen (O) 1.9%. The H{sup -} ion current decreased by about 20% when a tungsten (W) filament was used instead of a LaB{sub 6}-filament. The H{sup -} ion current could not be increased by seeding cesium (Cs) if the LaB{sub 6}-filament was used. On the other hand, it was increased to more than 70 mA with much lower arc current of 150 A if Cs was seeded when a W-filament was used.« less

A new IBA-AMS laboratory at the Comenius University in Bratislava (Slovakia)

NASA Astrophysics Data System (ADS)

Povinec, Pavel P.; Masarik, Jozef; Kúš, Peter; Holý, Karol; Ješkovský, Miroslav; Breier, Robert; Staníček, Jaroslav; Šivo, Alexander; Richtáriková, Marta; Kováčik, Andrej; Szarka, Ján; Steier, Peter; Priller, Alfred

2015-01-01

A Centre for Nuclear and Accelerator Technologies (CENTA) has been established at the Comenius University in Bratislava comprising of a tandem laboratory designed for Ion Beam Analysis (IBA), Ion Beam Modification (IBM) of materials and Accelerator Mass Spectrometry (AMS). The main equipment of the laboratory, i.e. Alphatross and MC-SNICS ion sources, 3 MV Pelletron tandem accelerator, and analyzers of accelerated ions are described. Optimization of ion beam characteristics for different ion sources with gas and solid targets, for transmission of accelerated ions with different energy and charge state, for different parameters of the high-energy ion analyzers, as well as first AMS results are presented. The scientific program of the CENTA will be devoted mainly to nuclear, environmental, life and material sciences.

The negative hydrogen Penning ion gauge ion source for KIRAMS-13 cyclotron

DOE Office of Scientific and Technical Information (OSTI.GOV)

An, D. H.; Jung, I. S.; Kang, J.

2008-02-15

The cold-cathode-type Penning ion gauge (PIG) ion source for the internal ion source of KIRAMS-13 cyclotron has been used for generation of negative hydrogen ions. The dc H-beam current of 650 {mu}A from the PIG ion source with the Dee voltage of 40 kV and arc current of 1.0 A is extrapolated from the measured dc extraction beam currents at the low extraction dc voltages. The output optimization of PIG ion source in the cyclotron has been carried out by using various chimneys with different sizes of the expansion gap between the plasma boundary and the chimney wall. This papermore » presents the results of the dc H-extraction measurement and the expansion gap experiment.« less

Improving the Sensitivity of Mass Spectrometer using a High-Pressure Electrodynamic Ion Funnel Interface

PubMed Central

Ibrahim, Yehia; Tang, Keqi; Tolmachev, Aleksey V.; Shvartsburg, Alexandre A.

2006-01-01

We report on a new electrodynamic ion funnel that operates at a pressure of 30 Torr with no loss of ion transmission. The enhanced performance compared to previous ion funnel designs optimized for pressures of <5 Torr was achieved by reducing the ion funnel capacitance and increasing the RF drive frequency (1.7 MHz) and amplitude (100-170 V peak-to-peak). No degradation of ion transmission was observed for pressures from 2 - 30 Torr. The ability to operate at higher pressure enabled a new tandem ion funnel mass spectrometer (MS) interface design that can accommodate a greater gas load. When combined with a multicapillary inlet, the interface provided more efficient introduction of ions, resulting in a significant enhancement in MS sensitivity and detection limits. PMID:16839773

Ion dynamics in a trapped ion mobility spectrometer†

PubMed Central

Hernandez, Diana Rosa; DeBord, John Daniel; Ridgeway, Mark E.; Kaplan, Desmond A.; Park, Melvin A.; Fernandez-Lima, Francisco

2014-01-01

In the present paper, theoretical simulations and experimental observations are used to describe the ion dynamics in a trapped ion mobility spectrometer. In particular, the ion motion, ion transmission and mobility separation are discussed as a function of the bath gas velocity, radial confinement, analysis time and speed. Mobility analysis and calibration procedure are reported for the case of sphere-like molecules for positive and negative ion modes. Results showed that a maximal mobility resolution can be achieved by optimizing the gas velocity, radial confinement (RF amplitude) and ramp speed (voltage range and ramp time). The mobility resolution scales with the electric field and gas velocity and R = 100–250 can be routinely obtained at room temperature. PMID:24571000

Design of Supercapacitor Electrodes Using Molecular Dynamics Simulations

NASA Astrophysics Data System (ADS)

Bo, Zheng; Li, Changwen; Yang, Huachao; Ostrikov, Kostya; Yan, Jianhua; Cen, Kefa

2018-06-01

Electric double-layer capacitors (EDLCs) are advanced electrochemical devices for energy storage and have attracted strong interest due to their outstanding properties. Rational optimization of electrode-electrolyte interactions is of vital importance to enhance device performance for practical applications. Molecular dynamics (MD) simulations could provide theoretical guidelines for the optimal design of electrodes and the improvement of capacitive performances, e.g., energy density and power density. Here we discuss recent MD simulation studies on energy storage performance of electrode materials containing porous to nanostructures. The energy storage properties are related to the electrode structures, including electrode geometry and electrode modifications. Altering electrode geometry, i.e., pore size and surface topography, can influence EDL capacitance. We critically examine different types of electrode modifications, such as altering the arrangement of carbon atoms, doping heteroatoms and defects, which can change the quantum capacitance. The enhancement of power density can be achieved by the intensified ion dynamics and shortened ion pathway. Rational control of the electrode morphology helps improve the ion dynamics by decreasing the ion diffusion pathway. Tuning the surface properties (e.g., the affinity between the electrode and the ions) can affect the ion-packing phenomena. Our critical analysis helps enhance the energy and power densities of EDLCs by modulating the corresponding electrode structures and surface properties.[Figure not available: see fulltext.

Radiation Damage to Nervous System: Designing Optimal Models for Realistic Neuron Morphology in Hippocampus

NASA Astrophysics Data System (ADS)

Batmunkh, Munkhbaatar; Bugay, Alexander; Bayarchimeg, Lkhagvaa; Lkhagva, Oidov

2018-02-01

The present study is focused on the development of optimal models of neuron morphology for Monte Carlo microdosimetry simulations of initial radiation-induced events of heavy charged particles in the specific types of cells of the hippocampus, which is the most radiation-sensitive structure of the central nervous system. The neuron geometry and particles track structures were simulated by the Geant4/Geant4-DNA Monte Carlo toolkits. The calculations were made for beams of protons and heavy ions with different energies and doses corresponding to real fluxes of galactic cosmic rays. A simple compartmental model and a complex model with realistic morphology extracted from experimental data were constructed and compared. We estimated the distribution of the energy deposition events and the production of reactive chemical species within the developed models of CA3/CA1 pyramidal neurons and DG granule cells of the rat hippocampus under exposure to different particles with the same dose. Similar distributions of the energy deposition events and concentration of some oxidative radical species were obtained in both the simplified and realistic neuron models.

Research Update: Focused ion beam direct writing of magnetic patterns with controlled structural and magnetic properties

NASA Astrophysics Data System (ADS)

Urbánek, Michal; Flajšman, Lukáš; Křižáková, Viola; Gloss, Jonáš; Horký, Michal; Schmid, Michael; Varga, Peter

2018-06-01

Focused ion beam irradiation of metastable Fe78Ni22 thin films grown on Cu(100) substrates is used to create ferromagnetic, body-centered cubic patterns embedded into paramagnetic, face-centered-cubic surrounding. The structural and magnetic phase transformation can be controlled by varying parameters of the transforming gallium ion beam. The focused ion beam parameters such as the ion dose, number of scans, and scanning direction can be used not only to control a degree of transformation but also to change the otherwise four-fold in-plane magnetic anisotropy into the uniaxial anisotropy along a specific crystallographic direction. This change is associated with a preferred growth of specific crystallographic domains. The possibility to create magnetic patterns with continuous magnetization transitions and at the same time to create patterns with periodical changes in magnetic anisotropy makes this system an ideal candidate for rapid prototyping of a large variety of nanostructured samples. Namely, spin-wave waveguides and magnonic crystals can be easily combined into complex devices in a single fabrication step.

Study of the thermal effect on silicon surface induced by ion beam from plasma focus device

NASA Astrophysics Data System (ADS)

Ahmad, Z.; Ahmad, M.; Al-Hawat, Sh.; Akel, M.

2017-04-01

Structural modifications in form of ripples and cracks are induced by nitrogen ions from plasma focus on silicon surface. The investigation of such structures reveals correlation between ripples and cracks formation in peripheral region of the melt spot. The reason of such correlation and structure formation is explained as result of thermal effect. Melting and resolidification of the center of irradiated area occur within one micro second of time. This is supported by a numerical simulation used to investigate the thermal effect induced by the plasma focus ion beams on the silicon surface. This simulation provides information about the temperature profile as well as the dynamic of the thermal propagation in depth and lateral directions. In accordance with the experimental observations, that ripples are formed in latter stage after the arrival of last ion, the simulation shows that the thermal relaxation takes place in few microseconds after the end of the ion beam arrival. Additionally, the dependency of thermal propagation and relaxation on the distance of the silicon surface from the anode is presented.

Preliminary Studies of Ions Emission in a Small Plasma Focus Device of Hundreds of Joules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moreno, Jose; Pavez, Cristian; Soto, Leopoldo

2009-01-21

Ion beam emission in plasma focus (PF) discharges was originally investigated to explain the strong forward anisotropy observed in the neutron. Several properties of PF emitted deuteron beams have been measured, including their angular distributions and energy spectra in devices operating with energies from 1 kJ to 1 MJ. At present there is a growing interest in the development of very small PF devices operating under 1 kJ. As part of the characterization program of the very low energy PF devices (<1 kJ) developed at the Chilean Nuclear Energy Commission, the charges particle emission in hydrogen (H{sub 2}) and mixturemore » (H{sub 2}+%Ar) are being studied. In order to obtain an estimation of the ions energy spectrum and ionization grade, by using time of flight method, a graphite collector system operating in the bias ion collector mode was constructed and it is being used. Preliminary results of the ion beams measurements in different experimental conditions, at a plasma focus device of 400 joules (PF-400 J) are presented.« less

Strategies to optimize lithium-ion supercapacitors achieving high-performance: Cathode configurations, lithium loadings on anode, and types of separator

NASA Astrophysics Data System (ADS)

Cao, Wanjun; Li, Yangxing; Fitch, Brian; Shih, Jonathan; Doung, Tien; Zheng, Jim

2014-12-01

The Li-ion capacitor (LIC) is composed of a lithium-doped carbon anode and an activated carbon cathode, which is a half Li-ion battery (LIB) and a half electrochemical double-layer capacitor (EDLC). LICs can achieve much more energy density than EDLC without sacrificing the high power performance advantage of capacitors over batteries. LIC pouch cells were assembled using activated carbon (AC) cathode and hard carbon (HC) + stabilized lithium metal power (SLMP®) anode. Different cathode configurations, various SLMP loadings on HC anode, and two types of separators were investigated to achieve the optimal electrochemical performance of the LIC. Firstly, the cathode binders study suggests that the PTFE binder offers improved energy and power performances for LIC in comparison to PVDF. Secondly, the mass ratio of SLMP to HC is at 1:7 to obtain the optimized electrochemical performance for LIC among all the various studied mass ratios between lithium loading amounts and active anode material. Finally, compared to the separator Celgard PP 3501, cellulose based TF40-30 is proven to be a preferred separator for LIC.

Iron Oxide Nanoparticle-Micelles (ION-Micelles) for Sensitive (Molecular) Magnetic Particle Imaging and Magnetic Resonance Imaging

PubMed Central

Starmans, Lucas W. E.; Burdinski, Dirk; Haex, Nicole P. M.; Moonen, Rik P. M.; Strijkers, Gustav J.; Nicolay, Klaas; Grüll, Holger

2013-01-01

Background Iron oxide nanoparticles (IONs) are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI) was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI. However, MPI requires magnetic particles with specific magnetic properties for optimal use. Current commercially available iron oxide formulations perform suboptimal in MPI, which is triggering research into optimized synthesis strategies. Most synthesis procedures aim at size control of iron oxide nanoparticles rather than control over the magnetic properties. In this study, we report on the synthesis, characterization and application of a novel ION platform for sensitive MPI and MRI. Methods and Results IONs were synthesized using a thermal-decomposition method and subsequently phase-transferred by encapsulation into lipidic micelles (ION-Micelles). Next, the material and magnetic properties of the ION-Micelles were analyzed. Most notably, vibrating sample magnetometry measurements showed that the effective magnetic core size of the IONs is 16 nm. In addition, magnetic particle spectrometry (MPS) measurements were performed. MPS is essentially zero-dimensional MPI and therefore allows to probe the potential of iron oxide formulations for MPI. ION-Micelles induced up to 200 times higher signal in MPS measurements than commercially available iron oxide formulations (Endorem, Resovist and Sinerem) and thus likely allow for significantly more sensitive MPI. In addition, the potential of the ION-Micelle platform for molecular MPI and MRI was showcased by MPS and MRI measurements of fibrin-binding peptide functionalized ION-Micelles (FibPep-ION-Micelles) bound to blood clots. Conclusions The presented data underlines the potential of the ION-Micelle nanoplatform for sensitive (molecular) MPI and warrants further investigation of the FibPep-ION-Micelle platform for in vivo, non-invasive imaging of fibrin in preclinical disease models of thrombus-related pathologies and atherosclerosis. PMID:23437371

Iron oxide nanoparticle-micelles (ION-micelles) for sensitive (molecular) magnetic particle imaging and magnetic resonance imaging.

PubMed

Starmans, Lucas W E; Burdinski, Dirk; Haex, Nicole P M; Moonen, Rik P M; Strijkers, Gustav J; Nicolay, Klaas; Grüll, Holger

2013-01-01

Iron oxide nanoparticles (IONs) are a promising nanoplatform for contrast-enhanced MRI. Recently, magnetic particle imaging (MPI) was introduced as a new imaging modality, which is able to directly visualize magnetic particles and could serve as a more sensitive and quantitative alternative to MRI. However, MPI requires magnetic particles with specific magnetic properties for optimal use. Current commercially available iron oxide formulations perform suboptimal in MPI, which is triggering research into optimized synthesis strategies. Most synthesis procedures aim at size control of iron oxide nanoparticles rather than control over the magnetic properties. In this study, we report on the synthesis, characterization and application of a novel ION platform for sensitive MPI and MRI. IONs were synthesized using a thermal-decomposition method and subsequently phase-transferred by encapsulation into lipidic micelles (ION-Micelles). Next, the material and magnetic properties of the ION-Micelles were analyzed. Most notably, vibrating sample magnetometry measurements showed that the effective magnetic core size of the IONs is 16 nm. In addition, magnetic particle spectrometry (MPS) measurements were performed. MPS is essentially zero-dimensional MPI and therefore allows to probe the potential of iron oxide formulations for MPI. ION-Micelles induced up to 200 times higher signal in MPS measurements than commercially available iron oxide formulations (Endorem, Resovist and Sinerem) and thus likely allow for significantly more sensitive MPI. In addition, the potential of the ION-Micelle platform for molecular MPI and MRI was showcased by MPS and MRI measurements of fibrin-binding peptide functionalized ION-Micelles (FibPep-ION-Micelles) bound to blood clots. The presented data underlines the potential of the ION-Micelle nanoplatform for sensitive (molecular) MPI and warrants further investigation of the FibPep-ION-Micelle platform for in vivo, non-invasive imaging of fibrin in preclinical disease models of thrombus-related pathologies and atherosclerosis.

Dynamics of ions generated by 2.3 kJ UNU/ICTP plasma focus device

NASA Astrophysics Data System (ADS)

Tangitsomboon, P.; Ngamrungroj, D.; Chandrema, E.; Mongkolnavin, R.

2017-09-01

UNU/ICTP Plasma Focus Device has been used as an ions source in many applications. In this paper, the full dynamic range of argon ions produced by the Plasma Focus Device from its initial phase through to beyond the focussing phase of the plasma is shown experimentally. The average speed of the ions is determined by measuring time taken for ions to reach different positions using magnetic probes and ion probes. Also, by adapting a well-established computational model that represents the dynamics of plasma in such device, it is also possible to determine the speed of these ions up to the point where the movement of the plasma sheath under the Lorentz force is completed. However, it was found that the speed determined by the computational model is higher in comparison with the values obtained experimentally at all different operating pressures. The ions’ speed found for operating pressure of 0.5 mbar, 1.0 mbar, 1.5 mbar and 2.0 mbar were 5.16 ± 0.04 cm/μs, 4.24 ± 0.04 cm/μs, 3.81 ± 0.03cm/μs and 3.16 ± 0.04 cm/μs respectively. These correspond to the ion energy of 551.38 ± 8.55 eV, 372.29 ± 7.02 eV, 300.61 ± 4.73 eV and 206.79 ± 5.24 eV.

Use of a radial self-field diode geometry for intense pulsed ion beam generation at 6 MeV on Hermes III

DOE PAGES

Renk, Timothy Jerome; Harper-Slaboszewicz, Victor Jozef; Mikkelson, Kenneth A.; ...

2014-12-15

We investigate the generation of intense pulsed focused ion beams at the 6 MeV level using an inductive voltage adder (IVA) pulsed-power generator, which employs a magnetically insulated transmission line (MITL). Such IVA machines typical run at an impedance of few tens of Ohms. Previous successful intense ion beam generation experiments have often featured an “axial” pinch-reflex ion diode (i.e., with an axial anode-cathode gap) and operated on a conventional Marx generator/water line driver with an impedance of a few Ohms and no need for an MITL. The goals of these experiments are to develop a pinch-reflex ion diode geometrymore » that has an impedance to efficiently match to an IVA, produces a reasonably high ion current fraction, captures the vacuum electron current flowing forward in the MITL, and focuses the resulting ion beam to small spot size. Furthermore, a new “radial” pinch-reflex ion diode (i.e., with a radial anode-cathode gap) is found to best demonstrate these properties. Operation in both positive and negative polarities was undertaken, although the negative polarity experiments are emphasized. Particle-in-cell (PIC) simulations are consistent with experimental results indicating that, for diode impedances less than the self-limited impedance of the MITL, almost all of the forward-going IVA vacuum electron flow current is incorporated into the diode current. PIC results also provide understanding of the diode-impedance and ion-focusing properties of the diode. Additionally, a substantial high-energy ion population is also identified propagating in the “reverse” direction, i.e., from the back side of the anode foil in the electron beam dump.« less

Use of a radial self-field diode geometry for intense pulsed ion beam generation at 6 MeV on Hermes III

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renk, T. J., E-mail: tjrenk@sandia.gov; Harper-Slaboszewicz, V.; Mikkelson, K. A.

2014-12-15

We investigate the generation of intense pulsed focused ion beams at the 6 MeV level using an inductive voltage adder (IVA) pulsed-power generator, which employs a magnetically insulated transmission line (MITL). Such IVA machines typical run at an impedance of few tens of Ohms. Previous successful intense ion beam generation experiments have often featured an “axial” pinch-reflex ion diode (i.e., with an axial anode-cathode gap) and operated on a conventional Marx generator/water line driver with an impedance of a few Ohms and no need for an MITL. The goals of these experiments are to develop a pinch-reflex ion diode geometry thatmore » has an impedance to efficiently match to an IVA, produces a reasonably high ion current fraction, captures the vacuum electron current flowing forward in the MITL, and focuses the resulting ion beam to small spot size. A new “radial” pinch-reflex ion diode (i.e., with a radial anode-cathode gap) is found to best demonstrate these properties. Operation in both positive and negative polarities was undertaken, although the negative polarity experiments are emphasized. Particle-in-cell (PIC) simulations are consistent with experimental results indicating that, for diode impedances less than the self-limited impedance of the MITL, almost all of the forward-going IVA vacuum electron flow current is incorporated into the diode current. PIC results also provide understanding of the diode-impedance and ion-focusing properties of the diode. In addition, a substantial high-energy ion population is also identified propagating in the “reverse” direction, i.e., from the back side of the anode foil in the electron beam dump.« less

Microchip and wedge ion funnels and planar ion beam analyzers using same

DOEpatents

Shvartsburg, Alexandre A; Anderson, Gordon A; Smith, Richard D

2012-10-30

Electrodynamic ion funnels confine, guide, or focus ions in gases using the Dehmelt potential of oscillatory electric field. New funnel designs operating at or close to atmospheric gas pressure are described. Effective ion focusing at such pressures is enabled by fields of extreme amplitude and frequency, allowed in microscopic gaps that have much higher electrical breakdown thresholds in any gas than the macroscopic gaps of present funnels. The new microscopic-gap funnels are useful for interfacing atmospheric-pressure ionization sources to mass spectrometry (MS) and ion mobility separation (IMS) stages including differential IMS or FAIMS, as well as IMS and MS stages in various configurations. In particular, "wedge" funnels comprising two planar surfaces positioned at an angle and wedge funnel traps derived therefrom can compress ion beams in one dimension, producing narrow belt-shaped beams and laterally elongated cuboid packets. This beam profile reduces the ion density and thus space-charge effects, mitigating the adverse impact thereof on the resolving power, measurement accuracy, and dynamic range of MS and IMS analyzers, while a greater overlap with coplanar light or particle beams can benefit spectroscopic methods.

How Constant Momentum Acceleration Decouples Energy and Space Focusing in Distance-of-Flight and Time-of-Flight Mass Spectrometries

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dennis, Elise; Gundlach-Graham, Alexander W.; Enke, Chris

2013-05-01

Time-of-flight (TOF) and distance-of-flight (DOF) mass spectrometers require means for focusing ions at the detector(s) because of initial dispersions of position and energy at the time of their acceleration. Time-of-flight mass spectrometers ordinarily employ constant energy acceleration (CEA), which creates a space-focus plane at which the initial spatial dispersion is corrected. In contrast, constant-momentum acceleration (CMA), in conjunction with an ion mirror, provides focus of the initial energy dispersion at the energy focus time for ions of all m/z at their respective positions along the flight path. With CEA, the initial energy dispersion is not simultaneously correctable as its effectmore » on ion velocity is convoluted with that of the spatial dispersion. The initial spatial dispersion with CMA remains unchanged throughout the field-free region of the flight path, so spatial dispersion can be reduced before acceleration. Improved focus is possible when each dispersion can be addressed independently. With minor modification, a TOF mass spectrometer can be operated in CMA mode by treating the TOF detector as though it were a single element in the array of detectors that would be used in a DOF mass spectrometer. Significant improvement in mass resolution is thereby achieved, albeit over a narrow range of m/z values. In this paper, experimental and theoretical results are presented that illustrate the energy-focusing capabilities of both DOF and TOF mass spectrometry.« less

An Rf Focused Interdigital Ion Accelerating Structure

DOE Office of Scientific and Technical Information (OSTI.GOV)

Swenson, D.A.

2003-08-26

An Rf Focused Interdigital (RFI) ion accelerating structure will be described. It represents an effective combination of the Wideroee (or interdigital) linac structure, used for many low frequency, heavy ion applications, and the rf electric quadrupole focusing used in the RFQ and RFD linac structures. As in the RFD linac structure, rf focusing is introduced into the RFI linac structure by configuring the drift tubes as two independent pieces operating at different electrical potentials as determined by the rf fields of the linac structure. Each piece (or electrode) of the RFI drift tube supports two fingers pointed inwards towards themore » opposite end of the drift tube forming a four-finger geometry that produces an rf quadrupole field along the axis of the linac for focusing the beam. However, because of the differences in the rf field configuration along the axis, the scheme for introducing rf focusing into the interdigital linac structure is quite different from that adopted for the RFD linac structure. The RFI linac structure promises to have significant size, efficiency, performance, and cost advantages over existing linac structures for the acceleration of low energy ion beams of all masses (light to heavy). These advantages will be reviewed. A 'cold model' of this new linac structure has been fabricated and the results of rf cavity measurements on this cold model will be presented.« less

Local modifications of magnetism and structure in FePt (001) epitaxial thin films by focused ion beam: Two-dimensional perpendicular patterns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Albertini, F.; Nasi, L.; Casoli, F.

Focused ion beam was utilized to locally modify magnetism and structure of L1{sub 0} FePt perpendicular thin films. As a first step, we have performed a magnetic, morphological, and structural study of completely irradiated FePt films with different Ga{sup +} doses (1x10{sup 13} -4x10{sup 16} ions/cm{sup 2}) and ion beam energy of 30 keV. For doses of 1x10{sup 14} ions/cm{sup 2} and above a complete transition from the ordered L1{sub 0} to the disordered A1 phase was found to occur, resulting in a drop of magnetic anisotropy and in the consequent moment reorientation from out-of-plane to in-plane. The lowest effectivemore » dose in disordering the structure (1x10{sup 14} ions/cm{sup 2}) was found not to affect the film morphology. Taking advantage of these results, continuous two-dimensional (2D) patterns of perpendicular magnetic structures (250 nm dots, 1 {mu}m dots, 1 {mu}m-large stripes) were produced by focused ion beam without affecting the morphology. The 2D patterns were revealed by means of magnetic force microscopy, that evidenced peculiar domain structures in the case of 1 {mu}m dots.« less

Design of high-energy high-current linac with focusing by superconducting solenoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batskikh, Guennady I.; Belugin, Vladimir M.; Bondarev, Boris I.

1995-09-15

The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac is presented in the report. In new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channel features allowmore » to decrease beam matched radius and increase a linac radiation purity without aperture growth. ''Regotron'' is used as high power generator in linac main part. But D and W cavities need not be divided into sections connected by RF-bridges which denuded them of high coupling factor.« less

Design of high-energy high-current linac with focusing by superconducting solenoids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Batskikh, G.I.; Belugin, V.M.; Bondarev, B.I.

1995-10-01

The advancement of MRTI design for 1.5 GeV and 250 mA ion CW linac was presented in a previous report. In this new linac version all the way from input to output the ions are focused by magnetic fields of superconducting solenoids. The ion limit current is far beyond the needed value. The linac focusing channel offers major advantages over the more conventional ones. The acceptance is 1.7 times as large for such focusing channel as for quadrupole one. Concurrently, a random perturbation sensitivity for such channel is one order of magnitude smaller than in quadrupole channel. These focusing channelmore » features allow to decrease beam matched radius and increase a linac radiation purity without aperture growth. {open_quotes}Regotron{close_quotes} is used as high power generator in linac main part. But D&W cavities need not be divided into sections connected by RF-bridges which denuded them of high coupling factor.« less

Optimization of reactive-ion etching (RIE) parameters for fabrication of tantalum pentoxide (Ta2O5) waveguide using Taguchi method

NASA Astrophysics Data System (ADS)

Muttalib, M. Firdaus A.; Chen, Ruiqi Y.; Pearce, S. J.; Charlton, Martin D. B.

2017-11-01

In this paper, we demonstrate the optimization of reactive-ion etching (RIE) parameters for the fabrication of tantalum pentoxide (Ta2O5) waveguide with chromium (Cr) hard mask in a commercial OIPT Plasmalab 80 RIE etcher. A design of experiment (DOE) using Taguchi method was implemented to find optimum RF power, mixture of CHF3 and Ar gas ratio, and chamber pressure for a high etch rate, good selectivity, and smooth waveguide sidewall. It was found that the optimized etch condition obtained in this work were RF power = 200 W, gas ratio = 80 %, and chamber pressure = 30 mTorr with an etch rate of 21.6 nm/min, Ta2O5/Cr selectivity ratio of 28, and smooth waveguide sidewall.

Design of a fast multileaf collimator for radiobiological optimized IMRT with scanned beams of photons, electrons, and light ions.

PubMed

Svensson, Roger; Larsson, Susanne; Gudowska, Irena; Holmberg, Rickard; Brahme, Anders

2007-03-01

Intensity modulated radiation therapy is rapidly becoming the treatment of choice for most tumors with respect to minimizing damage to the normal tissues and maximizing tumor control. Today, intensity modulated beams are most commonly delivered using segmental multileaf collimation, although an increasing number of radiation therapy departments are employing dynamic multileaf collimation. The irradiation time using dynamic multileaf collimation depends strongly on the nature of the desired dose distribution, and it is difficult to reduce this time to less than the sum of the irradiation times for all individual peak heights using dynamic leaf collimation [Svensson et al., Phys. Med. Biol. 39, 37-61 (1994)]. Therefore, the intensity modulation will considerably increase the total treatment time. A more cost-effective procedure for rapid intensity modulation is using narrow scanned photon, electron, and light ion beams in combination with fast multileaf collimator penumbra trimming. With this approach, the irradiation time is largely independent of the complexity of the desired intensity distribution and, in the case of photon beams, may even be shorter than with uniform beams. The intensity modulation is achieved primarily by scanning of a narrow elementary photon pencil beam generated by directing a narrow well focused high energy electron beam onto a thin bremsstrahlung target. In the present study, the design of a fast low-weight multileaf collimator that is capable of further sharpening the penumbra at the edge of the elementary scanned beam has been simulated, in order to minimize the dose or radiation response of healthy tissues. In the case of photon beams, such a multileaf collimator can be placed relatively close to the bremsstrahlung target to minimize its size. It can also be flat and thin, i.e., only 15-25 mm thick in the direction of the beam with edges made of tungsten or preferably osmium to optimize the sharpening of the penumbra. The low height of the collimator will minimize edge scatter from glancing incidence. The major portions of the collimator leafs can then be made of steel or even aluminum, so that the total weight of the multileaf collimator will be as low as 10 kg, which may even allow high-speed collimation in real time in synchrony with organ movements. To demonstrate the efficiency of this collimator design in combination with pencil beam scanning, optimal radiobiological treatments of an advanced cervix cancer were simulated. Different geometrical collimator designs were tested for bremsstrahlung, electron, and light ion beams. With a 10 mm half-width elementary scanned photon beam and a steel collimator with tungsten edges, it was possible to make as effective treatments as obtained with intensity modulated beams of full resolution, i.e., here 5 mm resolution in the fluence map. In combination with narrow pencil beam scanning, such a collimator may provide ideal delivery of photons, electrons, or light ions for radiation therapy synchronized to breathing and other organ motions. These high-energy photon and light ion beams may allow three-dimensional in vivo verification of delivery and thereby clinical implementation of the BioArt approach using Biologically Optimized three-dimensional in vivo predictive Assay based adaptive Radiation Therapy [Brahme, Acta Oncol. 42, 123-126 (2003)].

Computer Simulations of Ion Transport in Polymer Electrolyte Membranes.

PubMed

Mogurampelly, Santosh; Borodin, Oleg; Ganesan, Venkat

2016-06-07

Understanding the mechanisms and optimizing ion transport in polymer membranes have been the subject of active research for more than three decades. We present an overview of the progress and challenges involved with the modeling and simulation aspects of the ion transport properties of polymer membranes. We are concerned mainly with atomistic and coarser level simulation studies and discuss some salient work in the context of pure binary and single ion conducting polymer electrolytes, polymer nanocomposites, block copolymers, and ionic liquid-based hybrid electrolytes. We conclude with an outlook highlighting future directions.

Ion energy distribution near a plasma meniscus with beam extraction for multi element focused ion beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathew, Jose V.; Paul, Samit; Bhattacharjee, Sudeep

2010-05-15

An earlier study of the axial ion energy distribution in the extraction region (plasma meniscus) of a compact microwave plasma ion source showed that the axial ion energy spread near the meniscus is small ({approx}5 eV) and comparable to that of a liquid metal ion source, making it a promising candidate for focused ion beam (FIB) applications [J. V. Mathew and S. Bhattacharjee, J. Appl. Phys. 105, 96101 (2009)]. In the present work we have investigated the radial ion energy distribution (IED) under the influence of beam extraction. Initially a single Einzel lens system has been used for beam extractionmore » with potentials up to -6 kV for obtaining parallel beams. In situ measurements of IED with extraction voltages upto -5 kV indicates that beam extraction has a weak influence on the energy spread ({+-}0.5 eV) which is of significance from the point of view of FIB applications. It is found that by reducing the geometrical acceptance angle at the ion energy analyzer probe, close to unidirectional distribution can be obtained with a spread that is smaller by at least 1 eV.« less

Bright focused ion beam sources based on laser-cooled atoms

PubMed Central

McClelland, J. J.; Steele, A. V.; Knuffman, B.; Twedt, K. A.; Schwarzkopf, A.; Wilson, T. M.

2016-01-01

Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of the industry standard Ga+ liquid metal ion source. In this review we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future. PMID:27239245

Laser Ablation Electrodynamic Ion Funnel for In Situ Mass Spectrometry on Mars

NASA Technical Reports Server (NTRS)

Johnson, Paul V.; Hodyss, Robert P.; Tang, Keqi; Smith, Richard D.

2012-01-01

A front-end instrument, the laser ablation ion funnel, was developed, which would ionize rock and soil samples in the ambient Martian atmosphere, and efficiently transport the product ions into a mass spectrometer for in situ analysis. Laser ablation creates elemental ions from a solid with a high-power pulse within ambient Mars atmospheric conditions. Ions are captured and focused with an ion funnel into a mass spectrometer for analysis. The electrodynamic ion funnel consists of a series of axially concentric ring-shaped electrodes whose inside diameters (IDs) decrease over the length of the funnel. DC potentials are applied to each electrode, producing a smooth potential slope along the axial direction. Two radio-frequency (RF) AC potentials, equal in amplitude and 180 out of phase, are applied alternately to the ring electrodes. This creates an effective potential barrier along the inner surface of the electrode stack. Ions entering the funnel drift axially under the influence of the DC potential while being restricted radially by the effective potential barrier created by the applied RF. The net result is to effectively focus the ions as they traverse the length of the funnel.

Bright focused ion beam sources based on laser-cooled atoms

DOE Office of Scientific and Technical Information (OSTI.GOV)

McClelland, J. J.; Wilson, T. M.; Steele, A. V.

2016-03-15

Nanoscale focused ion beams (FIBs) represent one of the most useful tools in nanotechnology, enabling nanofabrication via milling and gas-assisted deposition, microscopy and microanalysis, and selective, spatially resolved doping of materials. Recently, a new type of FIB source has emerged, which uses ionization of laser cooled neutral atoms to produce the ion beam. The extremely cold temperatures attainable with laser cooling (in the range of 100 μK or below) result in a beam of ions with a very small transverse velocity distribution. This corresponds to a source with extremely high brightness that rivals or may even exceed the brightness of themore » industry standard Ga{sup +} liquid metal ion source. In this review, we discuss the context of ion beam technology in which these new ion sources can play a role, their principles of operation, and some examples of recent demonstrations. The field is relatively new, so only a few applications have been demonstrated, most notably low energy ion microscopy with Li ions. Nevertheless, a number of promising new approaches have been proposed and/or demonstrated, suggesting that a rapid evolution of this type of source is likely in the near future.« less

Batch versus column modes for the adsorption of radioactive metal onto rice husk waste: conditions optimization through response surface methodology.

PubMed

Kausar, Abida; Bhatti, Haq Nawaz; Iqbal, Munawar; Ashraf, Aisha

2017-09-01

Batch and column adsorption modes were compared for the adsorption of U(VI) ions using rice husk waste biomass (RHWB). Response surface methodology was employed for the optimization of process variables, i.e., (pH (A), adsorbent dose (B), initial ion concentration (C)) in batch mode. The B, C and C 2 affected the U(VI) adsorption significantly in batch mode. The developed quadratic model was found to be validated on the basis of regression coefficient as well as analysis of variance. The predicted and actual values were found to be correlated well, with negligible residual value, and B, C and C 2 were significant terms. The column study was performed considering bed height, flow rate and initial metal ion concentration, and adsorption efficiency was evaluated through breakthrough curves and bed depth service time and Thomas models. Adsorption was found to be dependent on bed height and initial U(VI) ion concentration, and flow rate decreased the adsorption capacity. Thomas models fitted well to the U(VI) adsorption onto RHWB. Results revealed that RHWB has potential to remove U(VI) ions and batch adsorption was found to be efficient versus column mode.

Solid-phase extraction of copper(II) in water and food samples using silica gel modified with bis(3-aminopropyl)amine and determination by flame atomic absorption spectrometry.

PubMed

Cagirdi, Duygu; Altundag, Hüseyin; Imamoglu, Mustafa; Tuzen, Mustafa

2014-01-01

A simple and selective separation and preconcentration method was developed for the determination of Cu(ll) ions. This method is based on adsorption of Cu(ll) ions from aqueous solution on a bis(3-aminopropyl)amine modified silica gel column and flame atomic absorption spectrometric determination after desorption. Various analytical parameters such as pH, type of eluent solution and its volume, flow rate of sample and eluent, and sample volume were optimized. Effects of some cation, anion, and transition metal ions on the recoveries of Cu(ll) ions were also investigated. Cu(ll) ions were quantitatively recovered at pH 6; 5.0 mL of 2 M HCI was used as the eluent. The preconcentration factor was found to be 150. The LOD was 0.12 microg/L for Cu(ll). The accuracy of the method was confirmed by analysis of Tea Leaves (INCT-TL-1) and Fish Protein (DORM-3) certified reference materials. The optimized method was applied to various water and food samples for the determination of Cu(ll).

Design and Comparative Study of O3/P2 Hybrid Structures for Room Temperature Sodium-Ion Batteries.

PubMed

Qi, Xingguo; Liu, Lilu; Song, Ningning; Gao, Fei; Yang, Kai; Lu, Yaxiang; Yang, Haitao; Hu, Yong-Sheng; Cheng, Zhao-Hua; Chen, Liquan

2017-11-22

Rechargeable sodium-ion batteries have drawn increasing attention as candidates for the post lithium-ion batteries in large-scale energy storage systems. Layered oxides are the most promising cathode materials and their pure phases (e.g., P2, O3) have been widely investigated. Here we report a series of cathode materials with O3/P2 hybrid phase for sodium-ion batteries, which possesses advantages of both P2 and O3 structures. The designed material, Na 0.78 Ni 0.2 Fe 0.38 Mn 0.42 O 2 , can deliver a capacity of 86 mAh g -1 with great rate capability and cycling performance. 66% capacity is still maintained when the current rate reaches as high as 10C, and the capacity retention is 90% after 1500 cycles. Moreover, in situ XRD was performed to examine the structure change during electrochemical testing in different voltage ranges, and the results demonstrate 4 V as the optimized upper voltage limit, with which smaller polarization, better structural stability, and better cycling performance are achieved. The results obtained here provide new insights in designing cathode materials with optimal structure and improved performance for sodium-ion batteries.

Optimization of plasma parameters with magnetic filter field and pressure to maximize H{sup −} ion density in a negative hydrogen ion source

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cho, Won-Hwi; Dang, Jeong-Jeung; Kim, June Young

2016-02-15

Transverse magnetic filter field as well as operating pressure is considered to be an important control knob to enhance negative hydrogen ion production via plasma parameter optimization in volume-produced negative hydrogen ion sources. Stronger filter field to reduce electron temperature sufficiently in the extraction region is favorable, but generally known to be limited by electron density drop near the extraction region. In this study, unexpected electron density increase instead of density drop is observed in front of the extraction region when the applied transverse filter field increases monotonically toward the extraction aperture. Measurements of plasma parameters with a movable Langmuirmore » probe indicate that the increased electron density may be caused by low energy electron accumulation in the filter region decreasing perpendicular diffusion coefficients across the increasing filter field. Negative hydrogen ion populations are estimated from the measured profiles of electron temperatures and densities and confirmed to be consistent with laser photo-detachment measurements of the H{sup −} populations for various filter field strengths and pressures. Enhanced H{sup −} population near the extraction region due to the increased low energy electrons in the filter region may be utilized to increase negative hydrogen beam currents by moving the extraction position accordingly. This new finding can be used to design efficient H{sup −} sources with an optimal filtering system by maximizing high energy electron filtering while keeping low energy electrons available in the extraction region.« less

Subsurface examination of a foliar biofilm using scanning electron- and focused-ion-beam microscopy

USDA-ARS?s Scientific Manuscript database

The dual beam scanning electron microscope, equipped with both a focused ion- and scanning electron- beam (FIB SEM) is a novel tool for the exploration of the subsurface structure of biological tissues. The FIB is capable of removing small cross sections to view the subsurface features and may be s...

Three-dimensional characterization of pigment dispersion in dried paint films using focused ion beam-scanning electron microscopy.

PubMed

Lin, Jui-Ching; Heeschen, William; Reffner, John; Hook, John

2012-04-01

The combination of integrated focused ion beam-scanning electron microscope (FIB-SEM) serial sectioning and imaging techniques with image analysis provided quantitative characterization of three-dimensional (3D) pigment dispersion in dried paint films. The focused ion beam in a FIB-SEM dual beam system enables great control in slicing paints, and the sectioning process can be synchronized with SEM imaging providing high quality serial cross-section images for 3D reconstruction. Application of Euclidean distance map and ultimate eroded points image analysis methods can provide quantitative characterization of 3D particle distribution. It is concluded that 3D measurement of binder distribution in paints is effective to characterize the order of pigment dispersion in dried paint films.

Electrostatic lens to focus an ion beam to uniform density

DOEpatents

Johnson, Cleland H.

1977-01-11

A focusing lens for an ion beam having a gaussian or similar density profile is provided. The lens is constructed to provide an inner zero electrostatic field, and an outer electrostatic field such that ions entering this outer field are deflected by an amount that is a function of their distance from the edge of the inner field. The result is a beam that focuses to a uniform density in a manner analogous to that of an optical ring lens. In one embodiment, a conically-shaped network of fine wires is enclosed within a cylindrical anode. The wire net together with the anode produces a voltage field that re-directs the outer particles of the beam while the axial particles pass undeflected through a zero field inside the wire net. The result is a focused beam having a uniform intensity over a given target area and at a given distance from the lens.

Laser driven ion accelerator

DOEpatents

Tajima, Toshiki

2006-04-18

A system and method of accelerating ions in an accelerator to optimize the energy produced by a light source. Several parameters may be controlled in constructing a target used in the accelerator system to adjust performance of the accelerator system. These parameters include the material, thickness, geometry and surface of the target.

Bunch Splitting Simulations for the JLEIC Ion Collider Ring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Satogata, Todd J.; Gamage, Randika

2016-05-01

We describe the bunch splitting strategies for the proposed JLEIC ion collider ring at Jefferson Lab. This complex requires an unprecedented 9:6832 bunch splitting, performed in several stages. We outline the problem and current results, optimized with ESME including general parameterization of 1:2 bunch splitting for JLEIC parameters.

Energetic Ion Beam Production by a Low-Pressure Plasma Focus Discharge

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, L. K.; Yap, S. L.; Wong, C. S.

Energetic ion beam emissions in a 3 kJ Mather type plasma focus operating at low-pressure regime are investigated. Deuterium gas is used and the discharge is operated in a low-pressure regime of below 1 mbar. Formation of the current sheath during the breakdown phase at the back wall is assisted by a set delayed trigger pulse. Energetic and intense ion beams with good reproducibility have been obtained for the operating pressure ranging from 0.05 mbar to 0.5 mbar. Deuteron beam is determined by time resolved measurement by making use of three biased ion collectors placed at the end on direction.more » The average energies of deuteron beams are resolved by using time-of flight method. Correlation between the ion emissions and the current sheath dynamics is also discussed.« less

Ultrasound-assisted dispersive magnetic solid phase extraction for preconcentration and determination of trace amount of Hg (II) ions from food samples and aqueous solution by magnetic graphene oxide (Fe3O4@GO/2-PTSC): Central composite design optimization.

PubMed

Keramat, Akram; Zare-Dorabei, Rouholah

2017-09-01

In this work, the synthesis of the magnetic graphene oxide modified by 2-pyridinecarboxaldehyde thiosemicarbazone groups (Fe 3 O 4 @GO/2-PTSC) was utilized for preconcentration and determination of mercuric ions in a trace amount by inductively coupled plasma-optical emission spectrometry (ICP-OES). Characterization of the adsorbent was performed using various techniques, such as FT-IR, VSM, SEM and XRD analysis. Central composite design (CCD) under response surface methodology (RSM) was used for obtaining the most important parameters and probable interactions in variables. The variables such as adsorbent dosage, pH, desorption time, and eluent volume was optimized. These values were 8mg, 5.4min, 0.5mL (HCl, 0.1M), respectively. Sonication had an important role in shortening the adsorption time of Hg (II) ions by enhancing the dispersion of adsorbent in solution. Under the optimal conditions, the proposed method presented high enrichment factor of 193, an extraction percentage of 96.5, a detection limit of 0.0079µgL -1 and a relative standard deviation (RSD %) of 1.63%. Finally, the application of the synthesized material was evaluated for preconcentration and determination of mercuric ions from foods and environmental waters samples. Copyright © 2017 Elsevier B.V. All rights reserved.

Polyaspartate extraction of cadmium ions from contaminated soil: Evaluation and optimization using central composite design.

PubMed

Mu'azu, Nuhu Dalhat; Haladu, Shamsuddeen A; Jarrah, Nabeel; Zubair, Mukarram; Essa, Mohammad H; Ali, Shaikh A

2018-01-15

The occurrences of heavy metal contaminated sites and soils and the need for devising environmentally friendly solutions have become global issues of serious concern. In this study, polyaspartate (a highly biodegradable agent) was synthesized using L-Aspartic acid via a new modified thermal procedure and employed for extraction of cadmium ions (Cd) from contaminated soil. Response surface methodology approach using 3 5 full faced centered central composite design was employed for modeling, evaluating and optimizing the influence of polyaspartate concentration (36-145mM), polyaspartate/soil ratio (5-25), initial heavy metal concentration (100-500mg/kg), initial pH (3-6) and extraction time (6-24h) on Cd ions extracted into the polyaspartate solution and its residual concentration in the treated soil. The Cd extraction efficacy obtained reached up to 98.8%. Increase in Cd extraction efficiency was associated with increase in the polyaspartate and Cd concentration coupled with lower polyaspertate/soil ratio and initial pH. Under the optimal conditions characterized with minimal utilization of the polyaspartate and high Cd ions removal, the extractible Cd in the polyaspartate solution reached up to 84.4mg/L which yielded 85% Cd extraction efficacy. This study demonstrates the suitability of using polyaspartate as an effective environmentally friendly chelating agent for Cd extraction from contaminated soils. Copyright © 2017 Elsevier B.V. All rights reserved.

Sample distribution in peak mode isotachophoresis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rubin, Shimon; Schwartz, Ortal; Bercovici, Moran, E-mail: mberco@technion.ac.il

We present an analytical study of peak mode isotachophoresis (ITP), and provide closed form solutions for sample distribution and electric field, as well as for leading-, trailing-, and counter-ion concentration profiles. Importantly, the solution we present is valid not only for the case of fully ionized species, but also for systems of weak electrolytes which better represent real buffer systems and for multivalent analytes such as proteins and DNA. The model reveals two major scales which govern the electric field and buffer distributions, and an additional length scale governing analyte distribution. Using well-controlled experiments, and numerical simulations, we verify andmore » validate the model and highlight its key merits as well as its limitations. We demonstrate the use of the model for determining the peak concentration of focused sample based on known buffer and analyte properties, and show it differs significantly from commonly used approximations based on the interface width alone. We further apply our model for studying reactions between multiple species having different effective mobilities yet co-focused at a single ITP interface. We find a closed form expression for an effective-on rate which depends on reactants distributions, and derive the conditions for optimizing such reactions. Interestingly, the model reveals that maximum reaction rate is not necessarily obtained when the concentration profiles of the reacting species perfectly overlap. In addition to the exact solutions, we derive throughout several closed form engineering approximations which are based on elementary functions and are simple to implement, yet maintain the interplay between the important scales. Both the exact and approximate solutions provide insight into sample focusing and can be used to design and optimize ITP-based assays.« less

Mega-Amp Opening Switch with Nested Electrodes/Pulsed Generator of Ion and Ion Cluster Beams

DTIC Science & Technology

1987-07-30

The use of a plasma focus as a mega-amp opening switch has been demonstrated by two modes of operation: (a) Single shot mode; (b) Repetitive Mode...energy level and under the same voltage and filling-pressure conditions but without field distortion elements. Misfirings of the plasma focus machine...are also virtually eliminated by using FDE at the coaxial electrode breech. The tests (based on about 10000 shots and five plasma focus machines

Extending the frontiers of mass spectrometric instrumentation and methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schieffer, Gregg Martin

2010-01-01

The focus of this dissertation is two-fold: developing novel analysis methods using mass spectrometry and the implementation and characterization of a novel ion mobility mass spectrometry instrumentation. The novel mass spectrometry combines ion trap for ion/ion reactions coupled to an ion mobility cell. The long term goal of this instrumentation is to use ion/ion reactions to probe the structure of gas phase biomolecule ions. The three ion source - ion trap - ion mobility - qTOF mass spectrometer (IT - IM - TOF MS) instrument is described. The analysis of the degradation products in coal (Chapter 2) and the imagingmore » plant metabolites (Appendix III) fall under the methods development category. These projects use existing commercial instrumentation (JEOL AccuTOF MS and Thermo Finnigan LCQ IT, respectively) for the mass analysis of the degraded coal products and the plant metabolites, respectively. The coal degradation paper discusses the use of the DART ion source for fast and easy sample analysis. The sample preparation consisted of a simple 50 fold dilution of the soluble coal products in water and placing the liquid in front of the heated gas stream. This is the first time the DART ion source has been used for analysis of coal. Steven Raders under the guidance of John Verkade came up with the coal degradation projects. Raders performed the coal degradation reactions, worked up the products, and sent them to me. Gregg Schieffer developed the method and wrote the paper demonstrating the use of the DART ion source for the fast and easy sample analysis. The plant metabolite imaging project extends the use of colloidal graphite as a sample coating for atmospheric pressure LDI. DC Perdian and I closely worked together to make this project work. Perdian focused on building the LDI setup whereas Schieffer focused on the MSn analysis of the metabolites. Both Perdian and I took the data featured in the paper. Perdian was the primary writer of the paper and used it as a chapter in his dissertation. Perdian and Schieffer worked together to address the revisions and publish it in Rapid Communications in Mass Spectrometry Journal.« less

Topology optimized gold nanostrips for enhanced near-infrared photon upconversion

NASA Astrophysics Data System (ADS)

Vester-Petersen, Joakim; Christiansen, Rasmus E.; Julsgaard, Brian; Balling, Peter; Sigmund, Ole; Madsen, Søren P.

2017-09-01

This letter presents a topology optimization study of metal nanostructures optimized for electric-field enhancement in the infrared spectrum. Coupling of such nanostructures with suitable ions allows for an increased photon-upconversion yield, with one application being an increased solar-cell efficiency by exploiting the long-wavelength part of the solar spectrum. In this work, topology optimization is used to design a periodic array of two-dimensional gold nanostrips for electric-field enhancements in a thin film doped with upconverting erbium ions. The infrared absorption band of erbium is utilized by simultaneously optimizing for two polarizations, up to three wavelengths, and three incident angles. Geometric robustness towards manufacturing variations is implemented considering three different design realizations simultaneously in the optimization. The polarization-averaged field enhancement for each design is evaluated over an 80 nm wavelength range and a ±15-degree incident angle span. The highest polarization-averaged field enhancement is 42.2 varying by maximally 2% under ±5 nm near-uniform design perturbations at three different wavelengths (1480 nm, 1520 nm, and 1560 nm). The proposed method is generally applicable to many optical systems and is therefore not limited to enhancing photon upconversion.

Intense ion beam generator

DOEpatents

Humphries, Jr., Stanley; Sudan, Ravindra N.

1977-08-30

Methods and apparatus for producing intense megavolt ion beams are disclosed. In one embodiment, a reflex triode-type pulsed ion accelerator is described which produces ion pulses of more than 5 kiloamperes current with a peak energy of 3 MeV. In other embodiments, the device is constructed so as to focus the beam of ions for high concentration and ease of extraction, and magnetic insulation is provided to increase the efficiency of operation.

Nitrogen Gas Field Ion Source (GFIS) Focused Ion Beam (FIB) Secondary Electron Imaging: A First Look.

PubMed

Schmidt, Marek E; Yasaka, Anto; Akabori, Masashi; Mizuta, Hiroshi

2017-08-01

The recent technological advance of the gas field ion source (GFIS) and its successful integration into systems has renewed the interest in the focused ion beam (FIB) technology. Due to the atomically small source size and the use of light ions, the limitations of the liquid metal ion source are solved as device dimensions are pushed further towards the single-digit nanometer size. Helium and neon ions are the most widely used, but a large portfolio of available ion species is desirable, to allow a wide range of applications. Among argon and hydrogen, $${\\rm N}_{2}^{{\\plus}} $$ ions offer unique characteristics due to their covalent bond and their use as dopant for various carbon-based materials including diamond. Here, we provide a first look at the $${\\rm N}_{2}^{{\\plus}} $$ GFIS-FIB enabled imaging of a large selection of microscopic structures, including gold on carbon test specimen, thin metal films on insulator and nanostructured carbon-based devices, which are among the most actively researched materials in the field of nanoelectronics. The results are compared with images acquired by He+ ions, and we show that $${\\rm N}_{2}^{{\\plus}} $$ GFIS-FIB can offer improved material contrast even at very low imaging dose and is more sensitive to the surface roughness.

Increasing ion and fusion yield in a dense plasma focus by combination of pre-ionization and heavy ion gas admixture

NASA Astrophysics Data System (ADS)

Farmanfarmaei, B.; Yousefi, H. R.; Salem, M. K.; Sari, A. H.

2018-04-01

The results of an experimental study of pre-ionization and heavy gas introduced into driven gas in a plasma focus device are reported. To achieve this purpose, we made use of two methods: first, the pre-ionization method by applying the shunt resistor and second, the admixture of heavy ions. We applied the different shunt resistors and found the optimum amount to be 200 MΩ at an optimum pressure of 0.5 Torr. Ion yield that was measured by array of Faraday cups and the energy of fast ions that was calculated by using the time-of-flight method were raised up to 22% and 45%, and the impurity caused by anode's erosion was reduced approximately by 67% in comparison to when there was no pre-ionization. Also, we have used the admixture of 5% argon ions with nitrogen (working gas) to improve the ion yield up to 45% in comparison with pure nitrogen. Finally, for the first time, we have utilized the combination of these methods together and have, consequently, reached the maximum ion yield and fusion yield. With this new method, ion yield raised up to 70% greater than that of the previous condition, i.e., without pre-ionization and heavy ion admixture.

Calibration of Nu-Instruments Noblesse multicollector mass spectrometers for argon isotopic measurements using a newly developed reference gas

USGS Publications Warehouse

Coble, M.A.; Grove, M.; Calvert, A.T.

2011-01-01

The greatest challenge limiting 40Ar/39Ar multicollection measurements is the availability of appropriate standard gasses to intercalibrate detectors. In particular, use of zoom lens ion-optics to steer and focus ion beams into a fixed detector array (i.e., Nu Instruments Noblesse) makes intercalibration of multiple detectors challenging because different ion-optic tuning conditions are required for optimal peak shape and sensitivity at different mass stations. We have found that detector efficiency and mass discrimination are affected by changes in ion-optic tuning parameters. Reliance upon an atmospheric Ar standard to calibrate the Noblesse is problematic because there is no straightforward way to relate atmospheric 40Ar and 36Ar to measurements of 40Ar and 39Ar if they are measured on separate detectors. After exploring alternative calibration approaches, we have concluded that calibration of the Noblesse is best performed using exactly the same source, detector, and ion-optic tuning settings as those used in routine 40Ar/39Ar analysis. To accomplish this, we have developed synthetic reference gasses containing 40Ar, 39Ar and 38Ar produced by mixing gasses derived from neutron-irradiated sanidine with an enriched 38Ar spike. We present a new method for calibrating the Noblesse based on use of both atmospheric Ar and the synthetic reference gasses. By combining atmospheric Ar and synthetic reference gas in different ways, we can directly measure 40Ar/39Ar, 38Ar/39Ar, and 36Ar/39Ar correction factors over ratios that vary from 0.5 to 460. These correction factors are reproducible to better than ??0.5??? (2?? standard error) over intervals spanning ~24h but can vary systematically by ~4% over 2weeks of continuous use when electron multiplier settings are held constant. Monitoring this variation requires daily calibration of the instrument. Application of the calibration method to 40Ar/39Ar multicollection measurements of widely used sanidine reference materials ACs-2, FCs-2, and TCs-2 demonstrate that calculated 40Ar*/39ArK can be accurately corrected to yield model 40Ar/39Ar ages consistent with those reported by Earthtime 40Ar/39Ar laboratories. Replicate analyses of 8-12 single-crystal sanidine ages are reproduced to within 1-2??? (2?? standard error) under optimal analytical conditions. This calibration technique is applicable over a wide range of isotopic ratios and signal sizes. Finally, the reference gas has the added advantage of facilitating straightforward characterization of electron multiplier dead time over a wide dynamic range. ?? 2011 Elsevier B.V.

Observation of Critical-Gradient Behavior in Alfvén-Eigenmode-Induced Fast-Ion Transport.

PubMed

Collins, C S; Heidbrink, W W; Austin, M E; Kramer, G J; Pace, D C; Petty, C C; Stagner, L; Van Zeeland, M A; White, R B; Zhu, Y B

2016-03-04

Experiments in the DIII-D tokamak show that fast-ion transport suddenly becomes stiff above a critical threshold in the presence of many overlapping small-amplitude Alfvén eigenmodes (AEs). The threshold is phase-space dependent and occurs when particle orbits become stochastic due to resonances with AEs. Above threshold, equilibrium fast-ion density profiles are unchanged despite increased drive, and intermittent fast-ion losses are observed. Fast-ion Dα spectroscopy indicates radially localized transport of the copassing population at radii that correspond to the location of midcore AEs. The observation of stiff fast-ion transport suggests that reduced models can be used to effectively predict alpha profiles, beam ion profiles, and losses to aid in the design of optimized scenarios for future burning plasma devices.

Optimization by infusion of multiple reaction monitoring transitions for sensitive quantification of peptides by liquid chromatography/mass spectrometry.

PubMed

Alghanem, Bandar; Nikitin, Frédéric; Stricker, Thomas; Duchoslav, Eva; Luban, Jeremy; Strambio-De-Castillia, Caterina; Muller, Markus; Lisacek, Frédérique; Varesio, Emmanuel; Hopfgartner, Gérard

2017-05-15

In peptide quantification by liquid chromatography/mass spectrometry (LC/MS), the optimization of multiple reaction monitoring (MRM) parameters is essential for sensitive detection. We have compared different approaches to build MRM assays, based either on flow injection analysis (FIA) of isotopically labelled peptides, or on the knowledge and the prediction of the best settings for MRM transitions and collision energies (CE). In this context, we introduce MRMOptimizer, an open-source software tool that processes spectra and assists the user in selecting transitions in the FIA workflow. MS/MS spectral libraries with CE voltages from 10 to 70 V are automatically acquired in FIA mode for isotopically labelled peptides. Then MRMOptimizer determines the optimal MRM settings for each peptide. To assess the quantitative performance of our approach, 155 peptides, representing 84 proteins, were analysed by LC/MRM-MS and the peak areas were compared between: (A) the MRMOptimizer-based workflow, (B1) the SRMAtlas transitions set used 'as-is'; (B2) the same SRMAtlas set with CE parameters optimized by Skyline. 51% of the three most intense transitions per peptide were shown to be common to both A and B1/B2 methods, and displayed similar sensitivity and peak area distributions. The peak areas obtained with MRMOptimizer for transitions sharing either the precursor ion charge state or the fragment ions with the SRMAtlas set at unique transitions were increased 1.8- to 2.3-fold. The gain in sensitivity using MRMOptimizer for transitions with different precursor ion charge state and fragment ions (8% of the total), reaches a ~ 11-fold increase. Isotopically labelled peptides can be used to optimize MRM transitions more efficiently in FIA than by searching databases. The MRMOptimizer software is MS independent and enables the post-acquisition selection of MRM parameters. Coefficients of variation for optimal CE values are lower than those obtained with the SRMAtlas approach (B2) and one additional peptide was detected. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

Self-Pinched Transport Theory for the SABRE Ion Diode

NASA Astrophysics Data System (ADS)

Welch, Dale R.; Olson, Craig L.; Hanson, David L.

1997-05-01

In anticipation of a 90 kA 4 MV SABRE ion diode experiment, we have been examining self-pinch transport of ions for application to ion-driven inertial confinement fusion. The Li^+3 beam will exit the diode with a 30-40 mradian divergence and a shallow focusing angle of 75 mradians. The beam is annular with an 4.6-cm inner radius and a 6.8-cm outer radius. Self-pinch theory and simulation predict that large residual currents are possible in 2-20 mtorr argon gas. The simulations suggest that ≈ 50 kA of Li particle current is necessary to contain the beam's transverse momentum. Some non-ideal effects include large beam divergence, large focusing angle and beam annularity. To address these problems, we have been studying the benefits of beam conditioning in the focus region between the diode and the self pinch region after the beam has reached a small radius. We have found some benefit from including a passive conical structure and a low-pressure gas. A significant lens effect can be attained using only the beam fields in vacuum or a low pressure gas. In this configuration, a large focusing force, that keeps the ions off an inner cone and outer wall as the beam converges, has been calculated using the numerical simulation code uc(iprop.) Results from integrated simulation of the condition cell and self-pinch region look encouraging.

Iron Homeostasis in Mycobacterium tuberculosis: Mechanistic Insights into Siderophore-Mediated Iron Uptake

PubMed Central

2016-01-01

Mycobacterium tuberculosis requires iron for normal growth but faces a limitation of the metal ion due to its low solubility at biological pH and the withholding of iron by the mammalian host. The pathogen expresses the Fe3+-specific siderophores mycobactin and carboxymycobactin to chelate the metal ion from insoluble iron and the host proteins transferrin, lactoferrin, and ferritin. Siderophore-mediated iron uptake is essential for the survival of M. tuberculosis, as knockout mutants, which were defective in siderophore synthesis or uptake, failed to survive in low-iron medium and inside macrophages. But as excess iron is toxic due to its catalytic role in the generation of free radicals, regulation of iron uptake is necessary to maintain optimal levels of intracellular iron. The focus of this review is to present a comprehensive overview of iron homeostasis in M. tuberculosis that is discussed in the context of mycobactin biosynthesis, transport of iron across the mycobacterial cell envelope, and storage of excess iron. The clinical significance of the serum iron status and the expression of the iron-regulated protein HupB in tuberculosis (TB) patients is presented here, highlighting the potential of HupB as a marker, notably in extrapulmonary TB cases. PMID:27402628

Recent ICRF coupling experiments on EAST

NASA Astrophysics Data System (ADS)

Yuqing, YANG; Xinjun, ZHANG; Yanping, ZHAO; Chengming, QIN; Yan, CHENG; Yuzhou, MAO; Hua, YANG; Jianhua, WANG; Shuai, YUAN; Lei, WANG; Songqing, JU; Gen, CHEN; Xu, DENG; Kai, ZHANG; Baonian, WAN; Jiangang, LI; Yuntao, SONG; Xianzu, GONG; Jinping, QIAN; Tao, ZHANG

2018-04-01

Recent ion cyclotron resonance frequency (ICRF) coupling experiments for optimizing ICRF heating in high power discharge were performed on EAST. The coupling experiments were focus on antenna phasing and gas puffing, which were performed separately on two ports of the ion cyclotron resonance heating (ICRH) system of EAST. The antenna phasing was performed on the I-port antenna, which consists of four toroidally spaced radiating straps operating in multiple phasing cases; the coupling performance was better under low wave number | {k}\\parallel | (ranging from 4.5 to 6.5). By fuelling the plasma from gas injectors, placed as uniformly spaced array from top to bottom at each side limiter of the B-port antenna, which works in dipole phasing, the coupling resistance of the B-port antenna increased obviously. Furthermore, the coupling resistance of the I-port antenna was insensitive to a smaller rate of gas puffing but when the gas injection rate was more than a certain value (>1021s‑1), a sharp increase in the coupling resistance of the I-port antenna occurred, which was mainly caused by the toroidal asymmetric boundary density arising from gas puffing. A more specific analysis is given in the paper.

Advancing Heliophysics and Space Weather Research with Student Internships and Faculty Development

NASA Astrophysics Data System (ADS)

Johnson, L. P.; Ng, C.; Marchese, P.; Austin, S. A.; Frost, J.; Cheung, T. K.; Tremberger, G.; Robbins, I.; Carlson, B. E.; Paglione, T.; Damas, C.; Steiner, J. C.; Rudolph, E.; Lewis, E.; Ford, K. S.; Cline, T.

2011-12-01

Expanding research capability in Heliophysics and Space Weather is the major focus of a collaboration between the City University of New York (CUNY) and NASA Goddard Space Fight Center (GSFC). The Heliophysics Education Consortium has a two-pronged approach centered on undergraduate research and faculty development. Summer 2011 student research projects include: Comparison of Fast Propagating Solar Waves and Slow Kelvin-Helmholtz Waves captured by SDO; Brightness Fluctuation of March 8, 2011 Eruption with Magnetic Rope Structure Measured by SDO; Investigation of Sunspot Regions, Coronal Mass Ejections and Solar Flares; An Integration and Testing Methodology for a Microsatellite; Comparative Analysis of Attitude Control Systems for Microsatellites; Spectral Analysis of Aerosols in Jupiter's Atmosphere Using HST Data; Alternative Sources of 5 GHz and 15 GHz Emissions in Active Galactic Nuclei; Probing Starburst-Driven Superwinds; Asteroid Astrometry; and Optimize an Electrostatic Deflection Element on PIXIES (Plasma Ion Experiment - Ion and Electron Sensor) for a CUNY student at GSFC. Faculty development workshops were conducted by Space Weather Action Center scientists. These workshops included a faculty development session at the CUNY Graduate Center and high school teachers professional development series at Queensborough Community College. The project is supported by NASA award NNX10AE72G.

Creation of High-Yield Polyhydroxyalkanoates Engineered Strains by Low Energy Ion Implantation

NASA Astrophysics Data System (ADS)

Qian, Shiquan; Cheng, Ying; Zhu, Suwen; Cheng, Beijiu

2008-12-01

Polyhydroxyalkanoates (PHAs), as a candidate for biodegradable plastic materials, can be synthesized by numerous microorganisms. However, as its production cost is high in comparison with those of chemically synthesized plastics, a lot of research has been focused on the efficient production of PHAs using different methods. In the present study, the mutation effects of PHAs production in strain pCB4 were investigated with implantation of low energy ions. It was found that under the implantation conditions of 7.8 × 1014 N+/cm2 at 10 keV, a high-yield PHAs strain with high genetic stability was generated from many mutants. After optimizing its fermentation conditions, the biomass, PHAs concentration and PHAs content of pCBH4 reached 2.26 g/L, 1.81 g/L, and 80.08% respectively, whereas its wild type controls were about 1.24 g/L, 0.61 g/L, and 49.20%. Moreover, the main constituent of PHAs was identified as poly-3-hydroxybutyrates (PHB) in the mutant stain and the yield of this compound was increased up to 41.33% in contrast to that of 27.78% in the wild type strain.

Few Atomic Layered Lithium Cathode Materials to Achieve Ultrahigh Rate Capability in Lithium-Ion Batteries.

PubMed

Tai, Zhixin; Subramaniyam, Chandrasekar M; Chou, Shu-Lei; Chen, Lingna; Liu, Hua-Kun; Dou, Shi-Xue

2017-09-01

The most promising cathode materials, including LiCoO 2 (layered), LiMn 2 O 4 (spinel), and LiFePO 4 (olivine), have been the focus of intense research to develop rechargeable lithium-ion batteries (LIBs) for portable electronic devices. Sluggish lithium diffusion, however, and unsatisfactory long-term cycling performance still limit the development of present LIBs for several applications, such as plug-in/hybrid electric vehicles. Motivated by the success of graphene and novel 2D materials with unique physical and chemical properties, herein, a simple shear-assisted mechanical exfoliation method to synthesize few-layered nanosheets of LiCoO 2 , LiMn 2 O 4 , and LiFePO 4 is used. Importantly, these as-prepared nanosheets with preferred orientations and optimized stable structures exhibit excellent C-rate capability and long-term cycling performance with much reduced volume expansion during cycling. In particular, the zero-strain insertion phenomenon could be achieved in 2-3 such layers of LiCoO 2 electrode materials, which could open up a new way to the further development of next-generation long-life and high-rate batteries. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

High Resolution Chemical Study of ALH84001

NASA Technical Reports Server (NTRS)

Conrad, Pamela G.; Douglas, Susanne; Kuhlman, Kimberly R.

2001-01-01

We have studied the chemistry of a sample of the SNC meteorite ALH84001 using an environmental scanning electron microscope (ESEM) with an energy dispersive chemical analytical detector and a focused ion beam secondary ion mass spectrometer (FIB-SIMS). Here we present the chemical data, both spectra and images, from two techniques that do not require sample preparation with a conductive coating, thus eliminating the possibility of preparation-induced textural artifacts. The FIB-SIMS instrument includes a column optimized for SEM with a quadrupole type mass spectrometer. Its spatial and spectral resolution are 20 nm and 0.4 AMU, respectively. The spatial resolution of the ESEM for chemical analysis is about 100 nm. Limits of detection for both instruments are mass dependent. Both the ESEM and the FIB-SIMS instrument revealed contrasting surficial features; crumbled, weathered appearance of the matrix in some regions as well as a rather ubiquitous presence of euhedral halite crystals, often associated with cracks or holes in the surface of the rock. Other halogen elements present in the vicinity of the NaCl crystals include K and Br. In this report, elemental inventories are shown as mass spectra and as X-ray maps.

Fabrication and demonstration of high energy density lithium ion microbatteries

NASA Astrophysics Data System (ADS)

Sun, Ke

Since their commercialization by Sony two decades ago, Li-ion batteries have only experienced mild improvement in energy and power performance, which remains one of the main hurdles for their widespread implementation in applications outside of powering compact portable devices, such as in electric vehicles. Li-ion batteries must be advanced through a disruptive technological development or a series of incremental improvements in chemistry and design in order to be competitive enough for advanced applications. As it will be introduced in this work, achieving this goal by new chemistries and chemical modifications does not seem to be promising in the short term, so efforts to fully optimize existing systems must be pursued at in parallel. This optimization must be mainly relying on the modification and optimizations of micro and macro structures of current battery systems. This kind of battery architecture study will be even more important when small energy storage devices are desired to power miniaturized and autonomous gadgets, such as MEMs, micro-robots, biomedical sensors, etc. In this regime, the limited space available makes requirements on electrode architecture more stringent and the assembly process more challenging. Therefore, the study of battery assembly strategies for Li-ion microbatteries will benefit not only micro-devices but also the development of more powerful and energetic large scale battery systems based on available chemistries. In chapter 2, preliminary research related to the mechanism for the improved rate capability of cathodes by amorphous lithium phosphate surficial films will be used to motivate the potential for structural optimization of existing commercial lithium ion battery electrode. In the following chapters, novel battery assembly techniques will be explored to achieve new battery architectures. In chapter 3, direct ink writing will be used to fabricate 3D interdigitated microbattery structures that have superior areal energy density on a limited footprint area. In chapter 4, Li-ion batteries based on the LiMn2O4-TiP 2O7 couple are manufactured on flexible paper substrates; where the use of light-weight paper substrates significantly increase the gravimetric energy density of this electrode couple as compared to traditional metal current collectors. In chapter 5, a novel nanowire growth mechanism will be explored to grow interdigitated metal oxide nanowire micro battery electrodes. The growth kinetics of this mechanism is systematically studied to understand how to optimize the growth process to produce electrodes with improved electrochemical properties.

Effects of anode geometry on forward wide-angle neon ion emissions in 3.5 kJ plasma focus device by novel mega-size panorama polycarbonate image detectors

NASA Astrophysics Data System (ADS)

Sohrabi, M.; Soltani, Z.; Sarlak, Z.

2018-03-01

Forward wide-angle neon ion emissions in a 3.5 kJ plasma focus device (PFD) were studied using 5 different anode top geometries; hollow-end cylinder, solid triangle, solid hemisphere, hollow-end cone and flat-end cone. Position-sensitive mega-size panorama polycarbonate ion image detectors (MS-PCID) developed by dual-cell circular mega-size electrochemical etching (MS-ECE) systems were applied for processesing wide-angle neon ion images on MS-PCIDs exposed on the PFD cylinder top base under a single pinch shot. The images can be simply observed, analyzed and relatively quantified in terms of ion emission angular distributions even by the unaided eyes. By analysis of the forward neon ion emission images, the ion emission yields, ion emission angular distributions, iso-fluence ion contours and solid angles of ion emissions in 4π PFD space were determined. The neon ion emission yields on the PFD cylinder top base are in an increasing order ~2.1×109, ~2.2 ×109, ~2.8×109, ~2.9×109, and ~3.5×109 neon ions/shot for the 5 stated anode top geometries respectively. The panorama neon ion images as diagnosed even by the unaided eyes demonstrate the lowest and highest ion yields from the hollow-end cylinder and flat-end cone anode tops respectively. Relative dynamic qualitative neon ion spectrometry was made by the unaided eyes demonstrating relative neon ion energy as they appear. The study also demonstrates the unique power of the MS-PCID/MS-ECE imaging system as an advanced state-of-the-art ion imaging method for wide-angle dynamic parametric studies in PFD space and other ion study applications.

Improving quantitative gas chromatography-electron ionization mass spectrometry results using a modified ion source: demonstration for a pharmaceutical application.

PubMed

D'Autry, Ward; Wolfs, Kris; Hoogmartens, Jos; Adams, Erwin; Van Schepdael, Ann

2011-07-01

Gas chromatography-mass spectrometry is a well established analytical technique. However, mass spectrometers with electron ionization sources may suffer from signal drifts, hereby negatively influencing quantitative performance. To demonstrate this phenomenon for a real application, a static headspace-gas chromatography method in combination with electron ionization-quadrupole mass spectrometry was optimized for the determination of residual dichloromethane in coronary stent coatings. Validating the method, the quantitative performance of an original stainless steel ion source was compared to that of a modified ion source. Ion source modification included the application of a gold coating on the repeller and exit plate. Several validation aspects such as limit of detection, limit of quantification, linearity and precision were evaluated using both ion sources. It was found that, as expected, the stainless steel ion source suffered from signal drift. As a consequence, non-linearity and high RSD values for repeated analyses were obtained. An additional experiment was performed to check whether an internal standard compound would lead to better results. It was found that the signal drift patterns of the analyte and internal standard were different, consequently leading to high RSD values for the response factor. With the modified ion source however, a more stable signal was observed resulting in acceptable linearity and precision. Moreover, it was also found that sensitivity improved compared to the stainless steel ion source. Finally, the optimized method with the modified ion source was applied to determine residual dichloromethane in the coating of coronary stents. The solvent was detected but found to be below the limit of quantification. Copyright © 2011 Elsevier B.V. All rights reserved.

Use of Additives to Improve Performance of Methyl Butyrate-Based Lithium-Ion Electrolytes

NASA Technical Reports Server (NTRS)

Smart, Marshall C.; Bugga, Ratnakumar V.

2011-01-01

This work addresses the need for robust rechargeable batteries that can operate well over a wide temperature range. To this end, a number of electrolyte formulations have been developed that incorporate the use of electrolyte additives to improve the high-temperature resilience, low-temperature power capability, and life characteristics of methyl butyrate-based electrolyte solutions. These electrolyte additives include mono-fluoroethylene carbonate (FEC), lithium oxalate, vinylene carbonate (VC), and lithium bis(oxalato)borate (LiBOB), which have been shown to result in improved high-temperature resilience of all carbonate-based electrolytes. Improved performance has been demonstrated of Li-ion cells with methyl butyrate-based electrolytes, including 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %); 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 4% FEC; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + lithium oxalate; 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 2% VC; and 1.20M LiPF6 in EC+EMC+MB (20:20:60 v/v %) + 0.10M LiBOB. These electrolytes have been shown to improve performance in MCMB-LiNiCoO2 and graphite-LiNi1/3Co1/3Mn1/3O2 experimental Li-ion cells. A number of LiPF6-based mixed carbonate electrolyte formulations have been developed that contain ester co-solvents, which have been optimized for operation at low temperature, while still providing reasonable performance at high temperature. For example, a number of ester co-solvents were investigated, including methyl propionate (MP), ethyl propionate (EP), methyl butyrate (MB), ethyl butyrate (EB), propyl butyrate (PB), and butyl butyrate (BB) in multi-component electrolytes of the following composition: 1.0M LiPF6 in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + X (20:60:20 v/v %) [where X = ester co-solvent]. ["Optimized Car bon ate and Ester-Based Li-Ion Electrolytes", NASA Tech Briefs, Vol. 32, No. 4 (April 2008), p. 56.] Focusing upon improved rate capability at low temperatures (i.e., 20 to 40 C), this approach was optimized further, resulting in the development of 1.20M LiPF6 in EC+EMC+MP (20:20:60 v/v %) and 1.20M LiPF6 in EC+EMC+EB (20:20:60 v/v %), which were demonstrated to operate well over a wide temperature range in MCMB-LiNiCoAlO2 and Li4Ti5O12(-)LiNiCoAlO2 prototype cells.

Lithium ion beam divergence on SABRE extraction ion diode experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hanson, D.L.; Cuneo, M.E.; Johnson, D.J.

Intense lithium beams are of particular interest for light ion inertial confinement fusion applications because lithium ions can be accelerated at high voltage in a single charge state (Li{sup +}) with a high mass-to-charge ratio and appropriate range for efficient focusing and heating of a hohlraum ICF target. Scaling to ion power densities adequate to drive high gain pellet implosions (600 TW at 30 MeV) will require a large number of beams transported, temporally bunched, and focused onto a target, with the necessary target standoff to ensure survival of the driver modules. For efficient long distance transport and focusing tomore » a small pellet, lithium beam divergence must be reduced to about 12 mrad or less (depending on the transport scheme). To support the eventual development of a light ion driver module for ICF applications, the authors are currently working to improve the composition, uniformity, and divergence of lithium ion beams produced by both passive LiF and active laser-generated lithium ion sources on extraction applied-B ion diodes on the SABRE accelerator (1 TW, 5 MV, 250 kA). While lithium beam divergence accounting and control are an essential goal of these experiments, divergence measurements for lithium beams present some unique problems not encountered to the same degree in divergence measurements on proton sources. To avoid these difficulties, the authors have developed a large aperture ion imaging diagnostic for time-resolved lithium divergence measurements. The authors will report on the operation of this lithium beam divergence diagnostic and on results of time-resolved divergence measurements in progress for passive LiF ion sources and laser-produced active lithium sources operated in diode configurations designed to control divergence growth. Comparisons will also be made with time-integrated divergence results obtained with small entrance aperture ultracompact pinhole cameras.« less

Laser-driven ion acceleration at BELLA

NASA Astrophysics Data System (ADS)

Bin, Jianhui; Steinke, Sven; Ji, Qing; Nakamura, Kei; Treffert, Franziska; Bulanov, Stepan; Roth, Markus; Toth, Csaba; Schroeder, Carl; Esarey, Eric; Schenkel, Thomas; Leemans, Wim

2017-10-01

BELLA is a high repetiton rate PW laser and we used it for high intensity laser plasma acceleration experiments. The BELLA-i program is focused on relativistic laser plasma interaction such as laser driven ion acceleration, aiming at establishing an unique collaborative research facility providing beam time to selected external groups for fundamental physics and advanced applications. Here we present our first parameter study of ion acceleration driven by the BELLA-PW laser with truly high repetition rate. The laser repetition rate of 1Hz allows for scanning the laser pulse duration, relative focus location and target thickness for the first time at laser peak powers of above 1 PW. Furthermore, the long focal length geometry of the experiment (f ∖65) and hence, large focus size provided ion beams of reduced divergence and unprecedented charge density. This work was supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.

Evaluation of Turner relaxed state as a model of long-lived ion-trapping structures in plasma focus and Z-pinches

NASA Astrophysics Data System (ADS)

Auluck, S. K. H.

2011-03-01

Relatively long-lived spheroidal structures coincident with the neutron emission phase have been observed in frozen deuterium fiber Z-pinch and some plasma focus devices. Existence of energetic ion-trapping mechanism in plasma focus has also been inferred from experimental data. It has been conjectured that these are related phenomena. This paper applies Turner's theory [L. Turner, IEEE Trans. Plasma Sci. 14, 849 (1986)] of relaxation of a Hall magnetofluid to construct a model of these structures and ion-trapping mechanism. Turner's solution modified for a finite-length plasma is used to obtain expressions for the magnetic field, velocity, and equilibrium pressure fields and is shown to represent an entity which is simultaneously a fluid vortex, a force-free magnetic field, a confined finite-pressure plasma, a charged object, and a trapped energetic ion beam. Characteristic features expected from diagnostic experiments are evaluated and shown to resemble experimental observations.

Distance-of-Flight Mass Spectrometry: What, Why, and How?

NASA Astrophysics Data System (ADS)

Dennis, Elise A.; Gundlach-Graham, Alexander W.; Ray, Steven J.; Enke, Christie G.; Hieftje, Gary M.

2016-11-01

Distance-of-flight mass spectrometry (DOFMS) separates ions of different mass-to-charge ( m/ z) by the distance they travel in a given time after acceleration. Like time-of-flight mass spectrometry (TOFMS), separation and mass assignment are based on ion velocity. However, DOFMS is not a variant of TOFMS; different methods of ion focusing and detection are used. In DOFMS, ions are driven orthogonally, at the detection time, onto an array of detectors parallel to the flight path. Through the independent detection of each m/ z, DOFMS can provide both wider dynamic range and increased throughput for m/ z of interest compared with conventional TOFMS. The iso-mass focusing and detection of ions is achieved by constant-momentum acceleration (CMA) and a linear-field ion mirror. Improved energy focus (including turn-around) is achieved in DOFMS, but the initial spatial dispersion of ions remains unchanged upon detection. Therefore, the point-source nature of surface ionization techniques could put them at an advantage for DOFMS. To date, three types of position-sensitive detectors have been used for DOFMS: a microchannel plate with a phosphorescent screen, a focal plane camera, and an IonCCD array; advances in detector technology will likely improve DOFMS figures-of-merit. In addition, the combination of CMA with TOF detection has provided improved resolution and duty factor over a narrow m/ z range (compared with conventional, single-pass TOFMS). The unique characteristics of DOFMS can enable the intact collection of large biomolecules, clusters, and organisms. DOFMS might also play a key role in achieving the long-sought goal of simultaneous MS/MS.

Ion optical design of a collinear laser-negative ion beam apparatus.

PubMed

Diehl, C; Wendt, K; Lindahl, A O; Andersson, P; Hanstorp, D

2011-05-01

An apparatus for photodetachment studies on atomic and molecular negative ions of medium up to heavy mass (M ≃ 500) has been designed and constructed. Laser and ion beams are merged in the apparatus in a collinear geometry and atoms, neutral molecules and negative ions are detected in the forward direction. The ion optical design and the components used to optimize the mass resolution and the transmission through the extended field-free interaction region are described. A 90° sector field magnet with 50 cm bending radius in combination with two slits is used for mass dispersion providing a resolution of M∕ΔM≅800 for molecular ions and M∕ΔM≅400 for atomic ions. The difference in mass resolution for atomic and molecular ions is attributed to different energy distributions of the sputtered ions. With 1 mm slits, transmission from the source through the interaction region to the final ion detector was determined to be about 0.14%.

Mobility-Selected Ion Trapping and Enrichment Using Structures for Lossless Ion Manipulations

DOE PAGES

Chen, Tsung-Chi; Ibrahim, Yehia M.; Webb, Ian K.; ...

2016-01-11

The integration of ion mobility spectrometry (IMS) with mass spectrometry (MS) and the ability to trap ions in IMS-MS measurements is of great importance for performing reactions, accumulating ions, and increasing analytical measurement sensitivity. The development of Structures for Lossless Ion Manipulations (SLIM) offers the potential for ion manipulations in a more reliable and cost-effective manner, while opening opportunities for much more complex sequences of manipulations. Here, we demonstrate an ion separation and trapping module and a method based upon SLIM that consists of a linear mobility ion drift region, a switch/tee and a trapping region that allows the isolationmore » and accumulation of mobility-separated species. The operation and optimization of the SLIM switch/tee and trap are described and demonstrated for the enrichment of the low abundance ions. Lastly, we observed a linear increase in ion intensity with the number of trapping/accumulation events using the SLIM trap, illustrating its potential for enhancing the sensitivity of low abundance or targeted species.« less

First results from negative ion beam extraction in ROBIN in surface mode

NASA Astrophysics Data System (ADS)

Pandya, Kaushal; Gahlaut, Agrajit; Yadav, Ratnakar K.; Bhuyan, Manas; Bandyopadhyay, Mainak; Das, B. K.; Bharathi, P.; Vupugalla, Mahesh; Parmar, K. G.; Tyagi, Himanshu; Patel, Kartik; Bhagora, Jignesh; Mistri, Hiren; Prajapati, Bhavesh; Pandey, Ravi; Chakraborty, Arun. K.

2017-08-01

ROBIN, the first step in the Indian R&D program on negative ion beams has reached an important milestone, with the production of negative ions in the surface conversion mode through Cesium (Cs) vapor injection into the source. In the present set-up, negative hydrogen ion beam extraction is effected through an extraction area of ˜73.38 cm2 (146 apertures of 8mm diameter). The three grid electrostatic accelerator system of ROBIN is fed by high voltage DC power supplies (Extraction Power Supply System: 11kV, 35A and Acceleration Power Supply System: 35kV, 15A). Though, a considerable reduction of co-extracted electron current is usually observed during surface mode operation, in order to increase the negative ion current, various other parameters such as plasma grid temperature, plasma grid bias, extraction to acceleration voltage ratio, impurity control and Cs recycling need to be optimized. In the present experiments, to control and to understand the impurity behavior, a Cryopump (14,000 l/s for Hydrogen) is installed along with a Residual Gas Analyzer (RGA). To characterize the source plasma, two sets of Langmuir probes are inserted through the diagnostic flange ports available at the extraction plane. To characterize the beam properties, thermal differential calorimeter, Doppler Shift Spectroscopy and electrical current measurements are implemented in ROBIN. In the present set up, all the negative ion beam extraction experiments have been performed by varying different experimental parameters e.g. RF power (30-70 kW), source operational pressure (0.3 - 0.6Pa), plasma grid bias voltage, extraction & acceleration voltage combination etc. The experiments in surface mode operation is resulted a reduction of co-extracted electron current having electron to ion ratio (e/i) ˜2 whereas the extracted negative ion current density was increased. However, further increase in negative ion current density is expected to be improved after a systematic optimization of the operational parameters and Cs conditioning of the source. It was also found out that a better performance of ROBIN is achieved in the pressure range: 0.5-0.6 Pa. In this paper, the preliminary results on parametric study of ROBIN operation and beam optimization in surface mode are discussed.

Li-ion site disorder driven superionic conductivity in solid electrolytes: a first-principles investigation of β-Li 3PS 4

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phani Dathar, Gopi Krishna; Balachandran, Janakiraman; Kent, Paul R. C.

The attractive safety and long-term stability of all solid-state batteries has added a new impetus to the discovery and development of solid electrolytes for lithium batteries. Recently several superionic lithium conducting solid electrolytes have been discovered. All the superionic lithium containing compounds (β-Li 3PS 4 and Li 10GeP 2S 12 and oxides, predominantly in the garnet phase) have partially occupied sites. This naturally begs the question of understanding the role of partial site occupancies (or site disorder) in optimizing ionic conductivity in these family of solids. In this paper, we find that for a given topology of the host lattice,more » maximizing the number of sites with similar Li-ion adsorption energies, which gives partial site occupancy, is a natural way to increase the configurational entropy of the system and optimize the conductivity. For a given topology and density of Li-ion adsorption sites, the ionic conductivity is maximal when the number of mobile Li-ions are equal to the number of mobile vacancies, also the very condition for achieving maximal configurational entropy. We demonstrate applicability of this principle by elucidating the role of Li-ion site disorder and the local chemical environment in the high ionic conductivity of β-Li 3PS 4. In addition, for β-Li 3PS 4 we find that a significant density of vacancies in the Li-ion sub-lattice (~25%) leads to sub-lattice melting at (~600 K) leading to a molten form for the Li-ions in an otherwise solid anionic host. This gives a lithium site occupancy that is similar to what is measured experimentally. We further show that quenching this disorder can improve conductivity at lower temperatures. As a consequence, we discover that (a) one can optimize ionic conductivity in a given topology by choosing a chemistry/composition that maximizes the number of mobile-carriers i.e. maximizing both mobile Li-ions and vacancies, and (b) when the concentration of vacancies becomes significant in the Li-ion sub-lattice, it becomes energetically as well as entropically favorable for it to remain molten well below the bulk decomposition temperature of the solid. Finally, this principle may already apply to several known superionic conducting solids.« less

Li-ion site disorder driven superionic conductivity in solid electrolytes: a first-principles investigation of β-Li 3PS 4

DOE PAGES

Phani Dathar, Gopi Krishna; Balachandran, Janakiraman; Kent, Paul R. C.; ...

2016-12-09

The attractive safety and long-term stability of all solid-state batteries has added a new impetus to the discovery and development of solid electrolytes for lithium batteries. Recently several superionic lithium conducting solid electrolytes have been discovered. All the superionic lithium containing compounds (β-Li 3PS 4 and Li 10GeP 2S 12 and oxides, predominantly in the garnet phase) have partially occupied sites. This naturally begs the question of understanding the role of partial site occupancies (or site disorder) in optimizing ionic conductivity in these family of solids. In this paper, we find that for a given topology of the host lattice,more » maximizing the number of sites with similar Li-ion adsorption energies, which gives partial site occupancy, is a natural way to increase the configurational entropy of the system and optimize the conductivity. For a given topology and density of Li-ion adsorption sites, the ionic conductivity is maximal when the number of mobile Li-ions are equal to the number of mobile vacancies, also the very condition for achieving maximal configurational entropy. We demonstrate applicability of this principle by elucidating the role of Li-ion site disorder and the local chemical environment in the high ionic conductivity of β-Li 3PS 4. In addition, for β-Li 3PS 4 we find that a significant density of vacancies in the Li-ion sub-lattice (~25%) leads to sub-lattice melting at (~600 K) leading to a molten form for the Li-ions in an otherwise solid anionic host. This gives a lithium site occupancy that is similar to what is measured experimentally. We further show that quenching this disorder can improve conductivity at lower temperatures. As a consequence, we discover that (a) one can optimize ionic conductivity in a given topology by choosing a chemistry/composition that maximizes the number of mobile-carriers i.e. maximizing both mobile Li-ions and vacancies, and (b) when the concentration of vacancies becomes significant in the Li-ion sub-lattice, it becomes energetically as well as entropically favorable for it to remain molten well below the bulk decomposition temperature of the solid. Finally, this principle may already apply to several known superionic conducting solids.« less

Morphology of Block Copolymer Electrolytes: A Numerical Self-Consistent Field Theory Study

NASA Astrophysics Data System (ADS)

Hou, Kevin; Qin, Jian

Engineering the morphology of ion-containing block copolymers is imperative for the optimization of their charge-transport and mechanical properties. Existing experiments have demonstrated that the addition of ions has a dramatic effect on the morphology and thermodynamic behavior of these structured electrolytes. We have developed an efficient, symmetry-adapted algorithm to calculate the ionic interactions in the SCFT for ion-containing polymers. We present the results of a numerical SCFT study examining how dielectric heterogeneity, ion concentration, and ion solvation affect morphology, domain spacing, ion distribution, and polymer density profiles. Particular attention is given to the detailed morphological analysis of the bicontinuous gyroidal phase, as well as the relevance of the aforementioned results to ionic conductivity.

Bioaccumulation of the Selected Metal Ions in Saccharomyces cerevisiae Cells Under Treatment of the Culture with Pulsed Electric Field (PEF).

PubMed

Pankiewicz, Urszula; Sujka, Monika; Jamroz, Jerzy

2015-12-01

The obtained results demonstrated an influence of PEF on increase in accumulation of various ions in S. cerevisiae cells. Optimization of particular PEF parameters and ions concentrations in the medium caused twofold increase in accumulation of magnesium and zinc ions and 3.5-fold higher accumulation of calcium ions in the cells. In the case of ion couple, accumulation of magnesium and zinc was, respectively, 1.5-fold and twofold higher in comparison to the control cultures. Yeast cells biomass enriched with Mg(2+), Zn(2+), Ca(2+) as well as Mg(2+) and Zn(2+) (simultaneously) may be an alternative for pharmacological supplementation applied in deficiency of these cations.

Students' Understanding of External Representations of the Potassium Ion Channel Protein, Part I: Affordances and Limitations of Ribbon Diagrams, Vines, and Hydrophobic/Polar Representations

ERIC Educational Resources Information Center

Harle, Marissa; Towns, Marcy H.

2012-01-01

Research on external representations in biochemistry has uncovered student difficulties in comprehending and interpreting external representations. This project focuses on students' understanding of three external representations of the potassium ion channel protein. This is part I of a two-part study, which focuses on the affordances and…

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs.

PubMed

Mangum, John S; Chan, Lisa H; Schmidt, Ute; Garten, Lauren M; Ginley, David S; Gorman, Brian P

2018-05-01

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice. Copyright © 2018 Elsevier B.V. All rights reserved.

Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

DOE PAGES

Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; ...

2018-02-23

Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In thismore » work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.« less

Uniform insulation applied-B ion diode

DOEpatents

Seidel, David B.; Slutz, Stephen A.

1988-01-01

An applied-B field extraction ion diode has uniform insulation over an anode surface for increased efficiency. When the uniform insulation is accomplished with anode coils, and a charge-exchange foil is properly placed, the ions may be focused at a point on the z axis.

Taeho Yoon | NREL

Science.gov Websites

postdoctoral fellow. He developed his expertise in electrochemistry and lithium-ion batteries (failure for lithium-ion batteries. His current research focuses on developing: 1) a fundamental understanding electrochemical performance of lithium-ion batteries. Research Interests Fundamental understanding of

Focusing giga-electronvolt heavy ions to micrometers at the Institute of Modern Physics.

PubMed

Sheng, Lina; Du, Guanghua; Guo, Jinlong; Wu, Ruqun; Song, Mingtao; Yuan, Youjin; Xiao, Guoqing

2013-05-01

To study the radiation effect of cosmic heavy ions of low fluxes in electronics and living samples, a focusing heavy ion microbeam facility, for ions with energies of several MeV/u up to 100 MeV/u, was constructed in the Institute of Modern Physics of the Chinese Academy of Sciences. This facility has a vertical design and an experiment platform for both in-vacuum analysis and in-air irradiation. Recently, microbeam of (12)C(6+) with energy of 80.55 MeV/u was successfully achieved at this interdisciplinary microbeam facility with a full beam spot size of 3 μm × 5 μm on target in air. Different from ions with energy of several MeV/u, the very high ion energy of hundred MeV/u level induces problems in beam micro-collimation, online beam spot diagnosis, radiation protection, etc. This paper presents the microbeam setup, difficulties in microbeam formation, and the preliminary experiments performed with the facility.

Orthogonal Injection Ion Funnel Interface Providing Enhanced Performance for Selected Reaction Monitoring-Triple Quadrupole Mass Spectrometry

PubMed Central

Chen, Tsung-Chi; Fillmore, Thomas L.; Prost, Spencer A.; Moore, Ronald J.; Ibrahim, Yehia M.; Smith, Richard D.

2016-01-01

The electrodynamic ion funnel facilitates efficient focusing and transfer of charged particles in the higher-pressure regions (e.g., ion source interfaces) of mass spectrometers, thus providing increased sensitivity. An “off-axis” ion funnel design has been developed to reduce the source contamination and interferences from, e.g. ESI droplet residue and other poorly focused neutral or charged particles with very high mass-to-charge ratios. In this study, a dual ion funnel interface consisting of an orthogonal higher pressure electrodynamic ion funnel (HPIF) and an ion funnel trap combined with a triple quadrupole mass spectrometer was developed and characterized. An orthogonal ion injection inlet and a repeller plate electrode was used to direct ions to an ion funnel HPIF at a pressure of 9–10 Torr. Key factors for the HPIF performance characterized included the effects of RF amplitude, the DC gradient, and operating pressure. Compared to the triple quadrupole standard interface more than 4-fold improvement in the limit of detection for the direct quantitative MS analysis of low abundance peptides was observed. The sensitivity enhancement in liquid chromatography selected reaction monitoring (LC-SRM) analyses of low-abundance peptides spiked into a highly complex mixture was also compared with that obtained using both a commercial S-lens interface and an in-line dual-ion funnel interface. PMID:26107611

Theoretical studies of defect formation and target heating by intense pulsed ion beams

NASA Astrophysics Data System (ADS)

Barnard, J. J.; Schenkel, T.; Persaud, A.; Seidl, P. A.; Friedman, A.; Grote, D. P.; Davidson, R. C.; Gilson, E. P.; Kaganovich, I.

2015-11-01

We present results of three studies related to experiments on NDCX-II, the Neutralized Drift Compression Experiment, a short-pulse (~ 1ns), high-current (~ 70A) linear accelerator for 1.2 MeV ions at LBNL. These include: (a) Coupled transverse and longitudinal envelope calculations of the final non-neutral ion beam transport, followed by neutralized drift and final focus, for a number of focus and drift lengths and with a series of ion species (Z =1-19). Predicted target fluences were obtained and target temperatures in the 1 eV range estimated. (b) HYDRA simulations of the target response for Li and He ions and for Al and Au targets at various ion fluences (up to 1012 ions/pulse/mm2) and pulse durations, benchmarking temperature estimates from the envelope calculations. (c) Crystal-Trim simulations of ion channeling through single-crystal lattices, with comparisons to ion transmission data as a function of orientation angle of the crystal foil and for different ion intensities and ion species. This work was performed under the auspices of the U.S. DOE under contracts DE-AC52-07NA27344 (LLNL), DE-AC02-05CH11231 (LBNL) and DE-AC02-76CH0307 (PPPL) and was supported by the US DOE Office of Science, Fusion Energy Sciences. LLNL-ABS-67521.

Measurement of ion beam angular distribution at different helium gas pressures in a plasma focus device by large-area polycarbonate detectors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sohrabi, M.; Habibi, M., E-mail: mortezahabibi@gmail.com; Ramezani, V.

2017-02-15

The paper presents an experimental study and analysis of full helium ion density angular distributions in a 4-kJ plasma focus device (PFD) at pressures of 10, 15, 25, and 30 mbar using large-area polycarbonate track detectors (PCTDs) (15-cm etchable diameter) processed by 50-Hz-HV electrochemical etching (ECE). Helium ion track distributions at different pressures, in particular, at the main axis of the PFD are presented. Maximum ion track density of ~4.4 × 10{sup 4} tracks/cm{sup 2} was obtained in the PCTD placed 6 cm from the anode. The ion distributions for all pressures applied are ring-shaped, which is possibly due tomore » the hollow cylindrical copper anode used. The large-area PCTD processed by ECE proves, at the present state-of-theart, a superior method for direct observation and analysis of ion distributions at a glance with minimum efforts and time. Some observations of the ion density distributions at different pressures are reported and discussed.« less

Concluding Remarks: Connecting Relativistic Heavy Ion Collisions and Neutron Star Mergers by the Equation of State of Dense Hadron- and Quark Matter as signalled by Gravitational Waves

NASA Astrophysics Data System (ADS)

Hanauske, Matthias; Steinheimer, Jan; Bovard, Luke; Mukherjee, Ayon; Schramm, Stefan; Takami, Kentaro; Papenfort, Jens; Wechselberger, Natascha; Rezzolla, Luciano; Stöcker, Horst

2017-07-01

The underlying open questions in the fields of general relativistic astrophysics and elementary particle and nuclear physics are strongly connected and their results are interdependent. Although the physical systems are quite different, the 4D-simulation of a merger of a binary system of two neutron stars and the properties of the hot and dense matter created in high energy heavy ion collisions, strongly depend on the equation of state of fundamental elementary matter. Neutron star mergers represent optimal astrophysical laboratories to investigate the QCD phase structure using a spectrogram of the post-merger phase of the emitted gravitational waves. These studies can be supplemented by observations from heavy ion collisions to possibly reach a conclusive picture on the QCD phase structure at high density and temperature. As gravitational waves (GWs) emitted from merging neutron star binaries are on the verge of their first detection, it is important to understand the main characteristics of the underlying merging system in order to predict the expected GW signal. Based on numerical-relativity simulations of merging neutron star binaries, the emitted GW and the interior structure of the generated hypermassive neutron stars (HMNS) have been analyzed in detail. This article will focus on the internal and rotational HMNS properties and their connection with the emitted GW signal. Especially, the appearance of the hadon-quark phase transition in the interior region of the HMNS and its conjunction with the spectral properties of the emitted GW will be addressed and confronted with the simulation results of high energy heavy ion collisions.

Mass spectrometric and theoretical investigation of sulfate clusters in nanoscale water droplets

NASA Astrophysics Data System (ADS)

Lemke, K.

2017-12-01

The solvation of sulfate clusters of varying size and charge in water clusters and in nanoscale water droplets has been studied using electrospray ionization (ESI) FT-MS and density functional theory (DFT) molecular simulations. ESI mass spectra of solvated [Mg(MgSO4)m]2+(H2O)n with m≤10 and up to 15 water molecules have been recorded, and ion cluster experiments have been undertaken using a custom-modified FT-ICR mass spectrometer with the ability of IRMPD for ion dissociation. We present equilibrium geometries and energies for [Mg(MgSO4)m]2+(H2O)n, water-free and solvated with up to 100 water molecules, using swarm-based optimizers and DFT level calculations. Dominant cluster species identified following ESI of dilute (1-5 mM) MgSO4 solutions include hexa- and octa-nuclear magnesium sulfate ions, water-free and with a full first shell of water molecules. The largest clusters identified are magnesium sulfate decamers, i.e. [Mg(MgSO4)10]2+(H2O)n, with n≤15. As a very first step towards understanding the distribution and intensity of ESI ion mass spectra, we have identified the global minima of [Mg(MgSO4)m]2+(H2O)n with m≤10 and n≤100, and located likely global minima of magnesium sulfate clusters in the gas phase and in nano-scale water droplets. We will present a summary of the structural and energetic trends of solvated magnesium sulfate clusters, with a particular focus on structural transitions induced by cluster growth and solvation, the occurrence of "magic" number cluster species, their energetic properties and their potential role as atmospheric aqueous species.

Chiral micellar electrokinetic chromatography (CMEKC)-atmospheric pressure photoionization of benzoin derivatives using mixed molecular micelles

PubMed Central

He, Jun; Shamsi, Shahab A.

2012-01-01

In the present work we report, for the first time, the successful on-line coupling of chiral micellar electrokinetic chromatography (CMEKC) to atmospheric pressure photo-ionization mass spectrometry (APPI-MS). Four structurally similar neutral test solutes (e.g., benzoin derivatives) were successfully ionized by APPI-MS. The mass spectra in the positive ion mode showed that the protonated molecular ions of benzoins are not the most abundant fragment ions. Simultaneous enantioseparation by CMEKC and on-line APPI-MS detection of four photoinitiators: hydrobenzoin (HBNZ), benzoin (BNZ), benzoin methyl ether (BME), benzoin ethyl ether (BEE), were achieved using an optimized molar ratio of mixed molecular micelle of two polymeric chiral surfactants (polysodium N-undecenoxy carbonyl-L-leucinate and polysodium N-undecenoyl-L,L-leucylvalinate). The CMEKC conditions, such as voltage, chiral polymeric surfactant concentration, buffer pH, and BGE concentration, were optimized using a multivariate central composite design (CCD). The sheath liquid composition (involving % v/v methanol, dopant concentration, electrolyte additive concentration, and flow rate) and spray chamber parameters (drying gas flow rate, drying gas temperature, and vaporizer temperature) were also optimized with CCD. Models built based on the CCD results and response surface method was used to analyze the interactions between factors and their effects on the responses. The final overall optimum conditions for CMEKC-APPI-MS were also predicted and found in agreement with the experimentally optimized parameters. PMID:21500208

On the Possibility of Creating a Point-Like Neutron Source

NASA Astrophysics Data System (ADS)

Golubev, S. V.; Skalyga, V. A.; Izotov, I. V.; Sidorov, A. V.; Razin, S. V.; Shaposhnikov, R. A.; Lapin, R. L.; Bokhanov, A. F.; Kazakov, M. Yu.

2018-03-01

We consider the possibility of creating a compact high-power neutron generator with a small emitting area (of the order of 100 μm) and a neutron yield of 1010s-1 on the basis of a deuterium-deuterium fusion reaction (or 1012 s-1 on the basis of a deuterium-tritium fusion reaction). The fusion takes place under bombardment of a deuterium- (or tritium-) saturated target by a high-current (about 100 mA) focused deuterium ion beam with an energy of 100 keV. The ion beam with total current at a level of hundreds of milliamperes and small emittance (less than 0.1 π·mm·mrad), which is crucial for sharp focusing, can be generated by a quasi-gas-dynamic ion source of a new generation created on the basis of a discharge in an open magnetic trap sustained by high-power electromagnetic radiation of the millimeter wavelength range under electron cyclotron resonance conditions. Simulations of the focusing system for the experimentally obtained ion beam show the possibility to create a deuterium ion beam with a transverse size of 200 μm on the neutron-forming target. Prospects for using such a neutron source for neutron tomography are discussed.

DBR laser with nondynamic plasma grating formed by focused ion beam implanted dopants

NASA Technical Reports Server (NTRS)

Boenke, Myra M.; Wu, M. C.; Wang, Shyh; Clark, William M., Jr.; Stevens, Eugene H.

1989-01-01

A static plasma grating has been demonstrated experimentally (Wu et al., 1988) in a large-optical-cavity focused-ion-beam-distributed-Bragg-reflector (FIB-DBR) GaAlAs/GaAs laser diode. The grating is formed by implanting stripes of dopants with a focused ion beam. The dopants ionize to form periodic fluctuations in the carrier concentration which, through the Kramers-Kronig relations, form an index grating. A model of the grating strength for optimizaton of the laser design is developed and presented. The computed results show that the coupling coefficient k can be increased by more than an order of magnitude over the 15/cm experimentally. Therefore, FIB-DBR or FIB-distributed-feedback (DFB) lasers with performance comparable to that of conventional DBR (or DFB) lasers can be expected.

Laser acceleration of electrons to giga-electron-volt energies using highly charged ions.

PubMed

Hu, S X; Starace, Anthony F

2006-06-01

The recent proposal to use highly charged ions as sources of electrons for laser acceleration [S. X. Hu and A. F. Starace, Phys. Rev. Lett. 88, 245003 (2002)] is investigated here in detail by means of three-dimensional, relativistic Monte Carlo simulations for a variety of system parameters, such as laser pulse duration, ionic charge state, and laser focusing spot size. Realistic laser focusing effects--e.g., the existence of longitudinal laser field components-are taken into account. Results of spatial averaging over the laser focus are also presented. These numerical simulations show that the proposed scheme for laser acceleration of electrons from highly charged ions is feasible with current or near-future experimental conditions and that electrons with GeV energies can be obtained in such experiments.

Understanding limiting factors in thick electrode performance as applied to high energy density Li-ion batteries

DOE PAGES

Du, Zhijia; Wood, David L.; Daniel, Claus; ...

2017-02-09

We present that increasing electrode thickness, thus increasing the volume ratio of active materials, is one effective method to enable the development of high energy density Li-ion batteries. In this study, an energy density versus power density optimization of LiNi 0.8Co 0.15Al 0.05O 2 (NCA)/graphite cell stack was conducted via mathematical modeling. The energy density was found to have a maximum point versus electrode thickness (critical thickness) at given discharging C rates. The physics-based factors that limit the energy/power density of thick electrodes were found to be increased cell polarization and underutilization of active materials. The latter is affected bymore » Li-ion diffusion in active materials and Li-ion depletion in the electrolyte phase. Based on those findings, possible approaches were derived to surmount the limiting factors. Finally, the improvement of the energy–power relationship in an 18,650 cell was used to demonstrate how to optimize the thick electrode parameters in cell engineering.« less

Some Aspects on the Mechanical Analysis of Micro-Shutters

NASA Technical Reports Server (NTRS)

Fettig, Rainer K.; Kuhn, Jonathan L.; Moseley, S. Harvey; Kutyrev, Alexander S.; Orloff, Jon; Lu, Shude

1999-01-01

An array of individually addressable micro-shutters is being designed for spectroscopic applications. Details of the design are presented in a companion paper. The mechanical design of a single shutter element has been completed. This design consists of a shutter blade suspended on a torsion beam manufactured out of single crystal silicon membranes. During operation the shutter blade will be rotated by 90 degrees out of the array plane. Thus, the stability and durability of the beams are crucial for the reliability of the devices. Structures were fabricated using focused ion beam milling in a FEI 620 dual beam machine, and subsequent testing was completed using the same platform. This allowed for short turn around times. We performed torsion and bending experiments to determine key characteristics of the membrane material. Results of measurements on prototype shutters were compared with the predictions of the numerical models. The data from these focused studies were used in conjunction with experiments and numerical models of shutter prototypes to optimize the design. In this work, we present the results of the material studies, and assess the mechanical performance of the resulting design.

Optimization of L(+)-Lactic Acid Fermentation Without Neutralisation of Rhizopus Oryzae Mutant RK02 by Low-Energy Ion Implantation

NASA Astrophysics Data System (ADS)

Li, Wen; Wang, Tao; Yang, Yingge; Liu, Dan; Fan, Yonghong; Wang, Dongmei; Yang, Qian; Yao, Jianming; Zheng, Zhiming; Yu, Zengliang

2008-04-01

In order to get an industrial strain which can yield a high concentration of lactic acid for ISPR (in situ product removal), the original strain Rhizopus oryzae RE3303 was mutated by low-energy ion beam implantation. A mutant RK02 was screened, and the factors such as the substrate concentration, nitrogen source concentration, inoculum size, seed age, aeration and temperature that affect the production of lactic acid were studied in detail. Under optimal conditions, the maximum concentration of L(+)-lactic acid reached 34.85 g/L after 30 h shake-flask cultivation without adding any neutralisation (5% Glucose added), which was a 146% increase in lactic acid production after ion implantation compared with the original strain. It was also shown that RK02 can be used in ISPR to reduce the number of times of separation.

SP70-alpha-benzoin oxime chelating resin for preconcentration-separation of Pb(II), Cd(II), Co(II) and Cr(III) in environmental samples.

PubMed

Narin, Ibrahim; Surme, Yavuz; Bercin, Erdogan; Soylak, Mustafa

2007-06-25

In the presented work, alpha-benzoin oxime immobilized SP70 chelating resin was synthesized for separation and preconcentration of Pb(II), Cd(II), Co(II) and Cr(III). The optimization procedure for analytical parameters including pH, eluent type, flow rate, etc. was examined in order to gain quantitative recoveries of analyte ions. The effects of foreign ions on the recoveries of studied metal ions were also investigated. The detection limits (3sigma) were found to be 16.0, 4.2, 1.3, 2.4microgL(-1) for Pb, Cd, Co and Cr, respectively. The preconcentration factor was 75 for Pb, 100 for Cd, Co and Cr. The optimized method was validated with certified reference materials and successfully applied to the waters, crops and pharmaceutical samples with good results (recoveries greater than 95%, R.S.D. lower than 10%).

Preparation of MgB2 superconducting microbridges by focused ion beam direct milling

NASA Astrophysics Data System (ADS)

Zhang, Xuena; Li, Yanli; Xu, Zhuang; Kong, Xiangdong; Han, Li

2017-01-01

MgB2 superconducting microbridges were prepared by focused ion beam (FIB) direct milling on MgB2 films. The surface topography of the microbridges were observed using SEM and AFM and the superconductivity was measured in this paper. Lots of cracks and holes were found near the milled area. And the superconducting transition temperature was decreased a lot and the bridges prepared were not superconducting due to ion damage after milled with large dose. Through these works, we explored the effect regular of FIB milling and experimental parameters on the performance of microbridges.

Comparison of heavy-ion- and electron-beam upset data for GaAS SRAMS. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Flesner, L.D.; Zuleeg, R.; Kolasinski, W.A.

1992-07-16

We report the results of experiments designed to evaluate the extent to which focused electron-beam pulses simulate energetic ion upset phenomena in GaAs memory circuits fabricated by the McDonnell Douglas Astronautics Company. The results of two experimental methods were compared, irradiation by heavy-ion particle beams, and upset mapping using focused electron pulses. Linear energy transfer (LET) thresholds and upset cross sections are derived from the data for both methods. A comparison of results shows good agreement, indicating that for these circuits electron-beam pulse mapping is a viable simulation technique.

Neutron Energy and Flux Distributions from a Crossed-Field Acceleration Model of Plasma Focus and Z-Pinch Discharges.

DTIC Science & Technology

plasma focus . A generalized beam-target model is assumed where (1) high-energy deuterons have angular distributions consistent with a crossed-field acceleration mechanism, and (2) these energetic deuterons undergo fusion collisions primarily with stationary target ions. Energy distributions of ions proportional to 1/(E sub d) cubed in the range from 50 to as high as 600 keV give computed results agreeing with many experimental observations at laboratory angles of 0, 90, and 180 deg. These ion-energy distributions can account for a 50- to 100-fold increase in neutron yeild

Selective demineralization of water by nanofiltration application to the defluorination of brackish water.

PubMed

Lhassani, A; Rumeau, M; Benjelloun, D; Pontie, M

2001-09-01

Nanofiltration is generally used to separate monovalent ions from divalent ions, but it is also possible to separate ions of the same valency by careful application of the transfer mechanisms involved. Analysis of the retention of halide salts reveals that small ions like fluoride are the best retained, and that this is even more marked under reduced pressure when selectivity is greatest. The selectivity desalination of fluorinated brackish water is hence feasible and drinking water can be produced directly at much lower cost than using reverse osmosis by optimizing the pressure for the type of water treated.

Extreme ultraviolet emission spectra of Gd and Tb ions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kilbane, D.; O'Sullivan, G.

2010-11-15

Theoretical extreme ultraviolet emission spectra of gadolinium and terbium ions calculated with the Cowan suite of codes and the flexible atomic code (FAC) relativistic code are presented. 4d-4f and 4p-4d transitions give rise to unresolved transition arrays in a range of ions. The effects of configuration interaction are investigated for transitions between singly excited configurations. Optimization of emission at 6.775 nm and 6.515 nm is achieved for Gd and Tb ions, respectively, by consideration of plasma effects. The resulting synthetic spectra are compared with experimental spectra recorded using the laser produced plasma technique.

TARDEC Collaboration - Energy Storage

DTIC Science & Technology

2010-12-07

Lithium - Ion Battery Pack Manufacturing • Advanced battery material scale-up facility • Electromagnetic Armor Power Maturation • Nickel-Zinc 6T...specification focused on 95% accuracy for SoC and SoH. • Lithium - Ion Battery Management Systems – Li-ion Battery OEMs produce BMS for their own battery

Preparation of a Light Focusing Glass Rod by Ion-Exchange Techniques

NASA Astrophysics Data System (ADS)

Pearson, A. David; French, William G.; Rawson, Eric G.

1969-07-01

A glass rod with a radially graduated refractive index was produced by replacing the lithium ions contained in the glass composition with sodium ions from a fused salt bath. Glass rods with such refractive index gradients are potentially useful as low resolution imaging devices.

Solvent extraction of gold using ionic liquid based process

NASA Astrophysics Data System (ADS)

Makertihartha, I. G. B. N.; Zunita, Megawati; Rizki, Z.; Dharmawijaya, P. T.

2017-01-01

In decades, many research and mineral processing industries are using solvent extraction technology for metal ions separation. Solvent extraction technique has been used for the purification of precious metals such as Au and Pd, and base metals such as Cu, Zn and Cd. This process uses organic compounds as solvent. Organic solvents have some undesired properties i.e. toxic, volatile, excessive used, flammable, difficult to recycle, low reusability, low Au recovery, together with the problems related to the disposal of spent extractants and diluents, even the costs associated with these processes are relatively expensive. Therefore, a lot of research have boosted into the development of safe and environmentally friendly process for Au separation. Ionic liquids (ILs) are the potential alternative for gold extraction because they possess several desirable properties, such as a the ability to expanse temperature process up to 300°C, good solvent properties for a wide range of metal ions, high selectivity, low vapor pressures, stability up to 200°C, easy preparation, environmentally friendly (commonly called as "green solvent"), and relatively low cost. This review paper is focused in investigate of some ILs that have the potentials as solvent in extraction of Au from mineral/metal alloy at various conditions (pH, temperature, and pressure). Performances of ILs extraction of Au are studied in depth, i.e. structural relationship of ILs with capability to separate Au from metal ions aggregate. Optimal extraction conditon in order to gain high percent of Au in mineral processing is also investigated.

Ablation plume structure and dynamics in ambient gas observed by laser-induced fluorescence imaging spectroscopy

NASA Astrophysics Data System (ADS)

Miyabe, M.; Oba, M.; Iimura, H.; Akaoka, K.; Khumaeni, A.; Kato, M.; Wakaida, I.

2015-08-01

The dynamic behavior of an ablation plume in ambient gas has been investigated by laser-induced fluorescence imaging spectroscopy. The second harmonic beam from an Nd:YAG laser (0.5-6 J/cm2) was focused on a sintered oxide pellet or a metal chip of gadolinium. The produced plume was subsequently intersected with a sheet-shaped UV beam from a dye laser so that time-resolved fluorescence images were acquired with an intensified CCD camera at various delay times. The obtained cross-sectional images of the plume indicate that the ablated ground state atoms and ions of gadolinium accumulate in a hemispherical contact layer between the plume and the ambient gas, and a cavity containing a smaller density of ablated species is formed near the center of the plume. At earlier expansion stage, another luminous component also expands in the cavity so that it coalesces into the hemispherical layer. The splitting and coalescence for atomic plume occur later than those for ionic plume. Furthermore, the hemispherical layer of neutral atoms appears later than that of ions; however, the locations of the layers are nearly identical. This coincidence of the appearance locations of the layers strongly suggests that the neutral atoms in the hemispherical layer are produced as a consequence of three-body recombination of ions through collisions with gas atoms. The obtained knowledge regarding plume expansion dynamics and detailed plume structure is useful for optimizing the experimental conditions for ablation-based spectroscopic analysis.

Optimized shielding for space radiation protection

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Cucinotta, F. A.; Kim, M. H.; Schimmerling, W.

2001-01-01

Future deep space mission and International Space Station exposures will be dominated by the high-charge and -energy (HZE) ions of the Galactic Cosmic Rays (GCR). A few mammalian systems have been extensively tested over a broad range of ion types and energies. For example, C3H10T1/2 cells, V79 cells, and Harderian gland tumors have been described by various track-structure dependent response models. The attenuation of GCR induced biological effects depends strongly on the biological endpoint, response model used, and material composition. Optimization of space shielding is then driven by the nature of the response model and the transmission characteristics of the given material.

Optimized Shielding for Space Radiation Protection

NASA Technical Reports Server (NTRS)

Wilson, J. W.; Cucinotta, F. A.; Kim, M.-H. Y.; Schimmerling, W.

2000-01-01

Abstract. Future deep space mission and International Space Station exposures will be dominated by the high-charge and -energy (HZE) ions of the Galactic Cosmic Rays (GCR). A few mammalian systems have been extensively tested over a broad range of ion types and energies. For example, C3H10T1/2 cells, V79 cells, and Harderian gland tumors have been described by various track-structure dependent response models. The attenuation of GCR induced biological effects depends strongly on the biological endpoint, response model used, and material composition. Optimization of space shielding is then driven by the nature of the response model and the transmission characteristics of the given material.

Outer-Planet Mission Analysis Using Solar-Electric Ion Propulsion

NASA Technical Reports Server (NTRS)

Woo, Byoungsam; Coverstone, Victoria L.; Hartmann, John W.; Cupples, Michael

2003-01-01

Outer-planet mission analysis was performed using three next generation solar-electric ion thruster models. Optimal trajectories are presented that maximize the delivered mass to the designated outer planet. Trajectories to Saturn and Neptune with a single Venus gravity assist are investigated. For each thruster model, the delivered mass versus flight time curve was generated to obtain thruster model performance. The effects of power to the thrusters and resonance ratio of Venutian orbital periods to spacecraft period were also studied. Multiple locally optimal trajectories to Saturn and Neptune have been discovered in different regions of the parameter search space. The characteristics of each trajectory are noted.

Atomistic origin of superior performance of ionic liquid electrolytes for Al-ion batteries.

PubMed

Kamath, Ganesh; Narayanan, Badri; Sankaranarayanan, Subramanian K R S

2014-10-14

Encouraged by recent experimental findings, here we report on an in silico investigation to probe the atomistic origin behind the superior performance of ionic liquids (ILs) over traditional carbonate electrolytes for Al-ion batteries. Fundamental insights from computationally derived thermodynamic and kinetic considerations coupled with an atomistic-level description of the solvation dynamics is used to elucidate the performance improvements. The formation of low-stability ion-solvent complexes in ILs facilitates rapid Al-ion solvation-desolvation and translates into favorable transport properties (viscosity and ionic conductivity). Our results offer encouraging prospects for this approach in the a priori prediction of optimal IL formulations for Al-ion batteries.

Noble gas cluster ions

NASA Astrophysics Data System (ADS)

Kaya, Yunus; Kalkan, Yalçin; Veenhof, Rob

2018-02-01

In this work, a reaction mechanism of formation of noble gas (Ng) cluster ions has been theoretically investigated in detail. The kinetic studies of formation of Xe+Xe cluster in Xe, Ar+Ar cluster ions in Ar, and Ne+Ne cluster ions in Ne have been made as theoretically. The optimized structures in the ground state were calculated using the density functional theory (DFT) by the B3LYP method combined with the Stuttgart/Dresden effective core potential basis set (SDD). In addition, we calculated the rate constants of all cluster formations. The results are 1.15 × 10-31, 3.58 × 10-31, 0.23 × 10-31cm6/s, respectively for Neon, Argon, Xenon cluster ions.

Optimized approach for Ion Proton RNA sequencing reveals details of RNA splicing and editing features of the transcriptome.

PubMed

Brown, Roger B; Madrid, Nathaniel J; Suzuki, Hideaki; Ness, Scott A

2017-01-01

RNA-sequencing (RNA-seq) has become the standard method for unbiased analysis of gene expression but also provides access to more complex transcriptome features, including alternative RNA splicing, RNA editing, and even detection of fusion transcripts formed through chromosomal translocations. However, differences in library methods can adversely affect the ability to recover these different types of transcriptome data. For example, some methods have bias for one end of transcripts or rely on low-efficiency steps that limit the complexity of the resulting library, making detection of rare transcripts less likely. We tested several commonly used methods of RNA-seq library preparation and found vast differences in the detection of advanced transcriptome features, such as alternatively spliced isoforms and RNA editing sites. By comparing several different protocols available for the Ion Proton sequencer and by utilizing detailed bioinformatics analysis tools, we were able to develop an optimized random primer based RNA-seq technique that is reliable at uncovering rare transcript isoforms and RNA editing features, as well as fusion reads from oncogenic chromosome rearrangements. The combination of optimized libraries and rapid Ion Proton sequencing provides a powerful platform for the transcriptome analysis of research and clinical samples.

Inert gas thrusters

NASA Technical Reports Server (NTRS)

Kaufman, H. R.

1976-01-01

Inert gases are of interest as possible alternatives to the usual electric thruster propellants of mercury and cesium. The multipole discharge chamber investigated was shown capable of low discharge chamber losses and flat ion beam profiles with a minimum of optimization. Minimum discharge losses were 200 to 250 eV/ion for xenon and 300 to 350 eV/ion for argon, while flatness parameters in the plane of the accelerator grid were 0.85 to 0.95. The design used employs low magnetic field strengths, which permits the use of sheet-metal parts. The corner problem of the discharge chamber was resolved with recessed corner anodes, which approximately equalized both the magnetic field above the anodes and the electron currents to these anodes. Argon hollow cathodes were investigated at currents up to about 5 amperes using internal thermionic emitters. Cathode chamber diameter optimized in the 1.0 to 2.5 cm range, while orifices diameter optimized in the 0.5 to 5 mm range. The use of a bias voltage for the internal emitter extended the operating range and facilitated starting. The masses of 15 and 30 cm flight type thrusters were estimated at about 4.2 and 10.8 kg.

Synthesis and characterization of oil palm empty fruit bunch-grafted-polyvinyl alcohol (OPEFB-g-PVA) hydrogel for removal of copper ions from aqueous solution

NASA Astrophysics Data System (ADS)

Wen, Soh Jing; Rabat, Nurul Ekmi; Osman, Noridah

2017-12-01

Oil palm empty fruit bunch (OPEFB) fiber is a natural polymer which is potentially used as efficient adsorbents for heavy metal cations. The main objective of this research is to synthesize OPEFB grafted polyvinyl alcohol (PVA) hydrogel by using ammonium persulfate (APS) as initiator and gelatin as crosslinking agent. The grafting temperature, amounts of cross linking agent, initiator and concentration of OPEFB were manipulated in order to optimize the swelling capability of the hydrogel. Comparison of heavy metal adsorption performance between pure PVA hydrogel and optimized OPEFB-g-PVA hydrogel was evaluated by using copper ions solution. The characteristics and structure of the optimized OPEFB-g-PVA hydrogel was studied by using Fourier Transform Infrared (FTIR) spectroscopy and Scanning Electron Microscopy (SEM) while Thermogravimetric Analysis (TGA) was used to study its thermal stability. The presence of band at 1088 and 1047cm-1 corresponds to C-O was observed as strong evidence of grafting. Water uptake capacity was evaluated and the maximum water absorption capacity was obtained at 180.67 g/g. PVA hydrogel with OPEFB proved to have better copper ion absorbency and thermal properties compared to pure PVA hydrogel.

Self-excitation of microwave oscillations in plasma-assisted slow-wave oscillators by an electron beam with a movable focus

NASA Astrophysics Data System (ADS)

Bliokh, Yu. P.; Nusinovich, G. S.; Shkvarunets, A. G.; Carmel, Y.

2004-10-01

Plasma-assisted slow-wave oscillators (pasotrons) operate without external magnetic fields, which makes these devices quite compact and lightweight. Beam focusing in pasotrons is provided by ions, which appear in the device due to the impact ionization of a neutral gas by beam electrons. Typically, the ionization time is on the order of the rise time of the beam current. This means that, during the rise of the current, beam focusing by ions becomes stronger. Correspondingly, a beam of electrons, which was initially diverging radially due to the self-electric field, starts to be focused by ions, and this focus moves towards the gun as the ion density increases. This feature makes the self-excitation of electromagnetic (em) oscillations in pasotrons quite different from practically all other microwave sources where em oscillations are excited by a stationary electron beam. The process of self-excitation of em oscillations has been studied both theoretically and experimentally. It is shown that in pasotrons, during the beam current rise the amount of current entering the interaction space and the beam coupling to the em field vary. As a result, the self-excitation can proceed faster than in conventional microwave sources with similar operating parameters such as the operating frequency, cavity quality-factor and the beam current and voltage.

Design and performance evaluation of a microfluidic ion-suppression module for anion-exchange chromatography.

PubMed

Wouters, Sam; Wouters, Bert; Jespers, Sander; Desmet, Gert; Eghbali, Hamed; Bruggink, Cees; Eeltink, Sebastiaan

2014-08-15

A microfluidic membrane suppressor has been constructed to suppress ions of alkaline mobile-phases via an acid-base reaction across a sulfonated poly(tetrafluoroethylene)-based membrane and was evaluated for anion-exchange separations using conductivity detection. The membrane was clamped between two chip substrates, accommodating rectangular microchannels for the eluent and regenerant flow, respectively. Additionally, a clamp-on chip holder has been constructed which allows the alignment and stacking of different chip modules. The response and efficacy of the microfluidic chip suppressor was assessed for a wide range of eluent (KOH) concentrations, using 127 and 183μm thick membranes, while optimizing the flow rate and concentration of the regenerant solution (H2SO4). The optimal operating eluent flow rate was determined at 5μL/min, corresponding to the optimal van-Deemter flow velocity of commercially-available column technology, i.e. a 0.4mm i.d.×250mm long column packed with 7.5μm anion-exchange particles. When equilibrated at 10mM KOH, a 99% decrease in conductivity signal could be obtained within 5min when applying 10mM H2SO4 regenerant at 75μL/min. A background signal as low as 1.2μS/cm was obtained, which equals the performance of a commercially-available electrolytic hollow-fiber suppressor. When increasing the temperature of the membrane suppressor from 15 to 20°C, ion suppression was significantly improved allowing the application of 75mM KOH. The applicability of the chip suppressor has been demonstrated with an isocratic baseline separation of a mixture of seven inorganic ions, yielding plate numbers between 5300 and 10,600 and with a gradient separation of a complex ion mixture. Copyright © 2014 Elsevier B.V. All rights reserved.

On the inter-instrument and the inter-laboratory transferability of a tandem mass spectral reference library: 2. Optimization and characterization of the search algorithm.

PubMed

Oberacher, Herbert; Pavlic, Marion; Libiseller, Kathrin; Schubert, Birthe; Sulyok, Michael; Schuhmacher, Rainer; Csaszar, Edina; Köfeler, Harald C

2009-04-01

A sophisticated matching algorithm developed for highly efficient identity search within tandem mass spectral libraries is presented. For the optimization of the search procedure a collection of 410 tandem mass spectra corresponding to 22 compounds was used. The spectra were acquired in three different laboratories on four different instruments. The following types of tandem mass spectrometric instruments were used: quadrupole-quadrupole-time-of-flight (QqTOF), quadrupole-quadrupole-linear ion trap (QqLIT), quadrupole-quadrupole-quadrupole (QqQ), and linear ion trap-Fourier transform ion cyclotron resonance mass spectrometer (LIT-FTICR). The obtained spectra were matched to an established MS/MS-spectral library that contained 3759 MS/MS-spectra corresponding to 402 different reference compounds. All 22 test compounds were part of the library. A dynamic intensity cut-off, the search for neutral losses, and optimization of the formula used to calculate the match probability were shown to significantly enhance the performance of the presented library search approach. With the aid of these features the average number of correct assignments was increased to 98%. For statistical evaluation of the match reliability the set of fragment ion spectra was extended with 300 spectra corresponding to 100 compounds not included in the reference library. Performance was checked with the aid of receiver operating characteristic (ROC) curves. Using the magnitude of the match probability as well as the precursor ion mass as benchmarks to rate the obtained top hit, overall correct classification of a compound being included or not included in the mass spectrometric library, was obtained in more than 95% of cases clearly indicating a high predictive accuracy of the established matching procedure. Copyright (c) 2009 John Wiley & Sons, Ltd.

Ozone-induced dissociation on a traveling wave high-resolution mass spectrometer for determination of double-bond position in lipids.

PubMed

Vu, Ngoc; Brown, Jeffery; Giles, Kevin; Zhang, Qibin

2017-09-15

The position of C=C within fatty acyl chains affects the biological function of lipids. Ozone-induced dissociation mass spectrometry (OzID-MS) has great potential in determination of lipid double-bond position, but has generally been implemented on low-resolution ion trap mass spectrometers. In addition, most of the OzID-MS experiments carried out so far were focused on the sodiated adducts of lipids; fragmentation of the most commonly observed protonated ions generated in LC/MS-based lipidomics workflow has been less explored. Ozone generated in line from an ozone generator was connected to the trap and transfer gas supply line of a Synapt G2 high-resolution mass spectrometer. Protonated ions of different phosphatidylcholines (PC) were generated by electrospray ionization through direct infusion. Different parameters, including traveling wave height and velocity, trap entrance and DC potential, were adjusted to maximize the OzID efficiency. sn-positional isomers and cis/trans isomers of lipids were compared for their reactivity with ozone. Traveling wave height and velocity were tuned to prolong the encounter time between lipid ions and ozone, and resulted in improved OzID efficiency, as did increasing trapping region DC and entrance potential. Under optimized settings, at least 1000 times enhancement in OzID efficiency was achieved compared to that under default settings for monounsaturated PC standards. Monounsaturated C=C in the sn-2 PC isomer reacted faster with ozone than the sn-1 isomer. Similarly, the C=C in trans PC reacted faster than in cis PC. This is the first implementation of OzID in the trap and transfer region of a traveling wave enabled high-resolution mass spectrometer. The OzID reaction efficiency is significantly improved by slowing down ions in the trap region for their prolonged interaction with ozone. This will facilitate application of high-resolution OzID-MS in lipidomics. Copyright © 2017 John Wiley & Sons, Ltd.

A new high transmission inlet for the Caltech nano-RDMA for size distribution measurements of sub-3 nm ions at ambient concentrations

NASA Astrophysics Data System (ADS)

Franchin, A.; Downard, A. J.; Kangasluoma, J.; Nieminen, T.; Lehtipalo, K.; Steiner, G.; Manninen, H. E.; Petäjä, T.; Flagan, R. C.; Kulmala, M.

2015-06-01

Reliable and reproducible measurements of atmospheric aerosol particle number size distributions below 10 nm require optimized classification instruments with high particle transmission efficiency. Almost all DMAs have an unfavorable potential gradient at the outlet (e.g. long column, Vienna type) or at the inlet (nano-radial DMA). This feature prevents them from achieving a good transmission efficiency for the smallest nanoparticles. We developed a new high transmission inlet for the Caltech nano-radial DMA (nRDMA) that increases the transmission efficiency to 12 % for ions as small as 1.3 nm in mobility equivalent diameter (corresponding to 1.2 × 10-4 m2 V-1 s-1 in electrical mobility). We successfully deployed the nRDMA, equipped with the new inlet, in chamber measurements, using a Particle Size Magnifier (PSM) and a booster Condensation Particle Counter (CPC) as a counter. With this setup, we were able to measure size distributions of ions between 1.3 and 6 nm, corresponding to a mobility range from 1.2 × 10-4 to 5.8 × 10-6 m2 V-1 s-1. The system was modeled, tested in the laboratory and used to measure negative ions at ambient concentrations in the CLOUD 7 measurement campaign at CERN. We achieved a higher size resolution than techniques currently used in field measurements, and maintained a good transmission efficiency at moderate inlet and sheath air flows (2.5 and 30 LPM, respectively). In this paper, by measuring size distribution at high size resolution down to 1.3 nm, we extend the limit of the current technology. The current setup is limited to ion measurements. However, we envision that future research focused on the charging mechanisms could extend the technique to measure neutral aerosol particles as well, so that it will be possible to measure size distributions of ambient aerosols from 1 nm to 1 μm.

Monitoring changes in membrane polarity, membrane integrity, and intracellular ion concentrations in Streptococcus pneumoniae using fluorescent dyes.

PubMed

Clementi, Emily A; Marks, Laura R; Roche-Håkansson, Hazeline; Håkansson, Anders P

2014-02-17

Membrane depolarization and ion fluxes are events that have been studied extensively in biological systems due to their ability to profoundly impact cellular functions, including energetics and signal transductions. While both fluorescent and electrophysiological methods, including electrode usage and patch-clamping, have been well developed for measuring these events in eukaryotic cells, methodology for measuring similar events in microorganisms have proven more challenging to develop given their small size in combination with the more complex outer surface of bacteria shielding the membrane. During our studies of death-initiation in Streptococcus pneumoniae (pneumococcus), we wanted to elucidate the role of membrane events, including changes in polarity, integrity, and intracellular ion concentrations. Searching the literature, we found that very few studies exist. Other investigators had monitored radioisotope uptake or equilibrium to measure ion fluxes and membrane potential and a limited number of studies, mostly in Gram-negative organisms, had seen some success using carbocyanine or oxonol fluorescent dyes to measure membrane potential, or loading bacteria with cell-permeant acetoxymethyl (AM) ester versions of ion-sensitive fluorescent indicator dyes. We therefore established and optimized protocols for measuring membrane potential, rupture, and ion-transport in the Gram-positive organism S. pneumoniae. We developed protocols using the bis-oxonol dye DiBAC4(3) and the cell-impermeant dye propidium iodide to measure membrane depolarization and rupture, respectively, as well as methods to optimally load the pneumococci with the AM esters of the ratiometric dyes Fura-2, PBFI, and BCECF to detect changes in intracellular concentrations of Ca(2+), K(+), and H(+), respectively, using a fluorescence-detection plate reader. These protocols are the first of their kind for the pneumococcus and the majority of these dyes have not been used in any other bacterial species. Though our protocols have been optimized for S. pneumoniae, we believe these approaches should form an excellent starting-point for similar studies in other bacterial species.