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At least 1,261 records · Page 70
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Injection simulations of space charge dominated proton beams in IOTA

A 2.5 MeV proton injector is being constructed for the IOTA ring at Fermilab to study the interaction of nonlinear integrable optics (NIO) with high space charge beams. Space charge in the transport line from the RFQ to the injection location has a significant current dependent effect on the phase space. Simulation studies to support efficient injection of intense bunches into IOTA are presented, included schemes to inject directly into NIO lattices.

Wieland, J. [Fermilab; Michigan State U.] (ORCID:0↗
DOE OSTI2011

Analysis of ICRH antenna loading data in TEXTOR obtained during gas injection experiments

The possibility of increasing the coupling of ICRH power to plasmas on TEXTOR by gas injection was investigated, for a given voltage applied at the input of an antenna pair. The antenna pair was operated in the conjugated T mode, D(H) heating was used. Modeling of the antenna by transmission line theory shows that load resilience is maintained in a broad range of independent resistance variation for each strap. It is found that the absolute value of the reflection coefficient can be maintained below 0.2 for typical values of resistance measured in plasma shots (2-10 {Omega}/m) in good matching conditions. During gas injection, the loading resistance showed a clear increase with increasing line average electron density measured close to the plasma edge. Evidence of fast wave eigenmodes was also found, as characteristic resonant behavior of loading resistance and antenna self-inductance, due to poor absorption in the plasma caused by high H minority concentration.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2014

Electrical and optical characterization of Au/CaF{sub 2}/p-Si(111) tunnel-injection diodes

Metal/CaF{sub 2}/p-Si(111) capacitors with the improved-quality several-nanometer-thick epitaxial fluorite films are examined, aiming at solidifying a candidacy of this material for barrier layers in silicon devices. Structural and transport properties of a thin crystalline dielectric are characterized by different experimental techniques. The measured current-voltage characteristics accompanied with simulation results demonstrate that the elastic tunneling electron injection takes place in the considered structures. The same result follows from the behavior of hot-electron-injection-related electroluminescence within the selected spectral intervals. The result is important considering a perspective of using the epitaxial fluorides as barrier layers in resonant tunneling diodes.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Electron-electron scattering-induced channel hot electron injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors with high-k/metal gate stacks

This work investigates electron-electron scattering (EES)-induced channel hot electron (CHE) injection in nanoscale n-channel metal-oxide-semiconductor field-effect-transistors (n-MOSFETs) with high-k/metal gate stacks. Many groups have proposed new models (i.e., single-particle and multiple-particle process) to well explain the hot carrier degradation in nanoscale devices and all mechanisms focused on Si-H bond dissociation at the Si/SiO{sub 2} interface. However, for high-k dielectric devices, experiment results show that the channel hot carrier trapping in the pre-existing high-k bulk defects is the main degradation mechanism. Therefore, we propose a model of EES-induced CHE injection to illustrate the trapping-dominant mechanism in nanoscale n-MOSFETs with high-k/metal gate stacks.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

On the mechanisms of cation injection in conducting bridge memories: The case of HfO{sub 2} in contact with noble metal anodes (Au, Cu, Ag)

Resistance switching is studied in HfO{sub 2} as a function of the anode metal (Au, Cu, and Ag) in view of its application to resistive memories (resistive random access memories, RRAM). Current-voltage (I-V) and current-time (I-t) characteristics are presented. For Au anodes, resistance transition is controlled by oxygen vacancies (oxygen-based resistive random access memory, OxRRAM). For Ag anodes, resistance switching is governed by cation injection (Conducting Bridge random access memory, CBRAM). Cu anodes lead to an intermediate case. I-t experiments are shown to be a valuable tool to distinguish between OxRRAM and CBRAM behaviors. A model is proposed to explain the high-to-low resistance transition in CBRAMs. The model is based on the theory of low-temperature oxidation of metals (Cabrera-Mott theory). Upon electron injection, oxygen vacancies and oxygen ions are generated in the oxide. Oxygen ions are drifted to the anode, and an interfacial oxide is formed at the HfO{sub 2}/anode interface. If oxygen ion mobility is low in the interfacial oxide, a negative space charge builds-up at the HfO{sub 2}/oxide interface. This negative space charge is the source of a strong electric field across the interfacial oxide thickness, which pulls out cations from the anode (CBRAM case). Inversely, if oxygen ions migration through the interfacial oxide is important (or if the anode does not oxidize such as Au), bulk oxygen vacancies govern resistance transition (OxRRAM case).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2018

Anomalous Fast-Ion Transport During Neutral Beam Injection on EAST

The fast-ion transport during neutral beam injection on the Experimental Advanced Superconducting Tokamak (EAST) is studied. Based on the NUBEAM and TRANSP codes, it is found that fast-ion transport is anomalous when the minimum safety factor (q{sub min}) is about 2, while it is neoclassical when q{sub min} is around 1. Neutral beam injection heating efficiency, plasma stored energy, and the total heating power are reduced when the fast ion transport is anomalous. The Alfvén continuum spectrum and the mode structures of toroidal Alfvén eigenmodes (AEs) are also calculated for comparison between neoclassical fast-ion transport and anomalous fast-ion transport. High-q{sub min} discharge with anomalous fast-ion transport has more AE activity than that of lower q{sub min} discharge with neoclassical fast-ion transport.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2017

CO2 Push-Pull Single Fault Injection Simulations

ASCII text files containing grid-block name, X-Y-Z location, and multiple parameters from TOUGH2 simulation output of CO2 injection into an idealized single fault representing a dipping normal fault at the Desert Peak geothermal field (readable by GMS). The fault is composed of a damage zone, a fault gouge and a slip plane. The runs are described in detail in the following: Borgia A., Oldenburg C.M., Zhang R., Jung Y., Lee K.J., Doughty C., Daley T.M., Chugunov N., Altundas B, Ramakrishnan T.S., 2017. Carbon Dioxide Injection for Enhanced Characterization of Faults and Fractures in Geothermal Systems. Proceedings of the 42st Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, February 13-17.

15 GEOTHERMAL ENERGY↗
DOE OSTI2012

Advanced Production Surface Preparation Technology Development for Ultra-High Pressure Diesel Injection

In 2007, An Ultra High Injection Pressure (UHIP) fueling method has been demonstrated by Caterpillar Fuel Systems - Product Development, demonstrating ability to deliver U.S. Environment Protection Agency (EPA) Tier 4 Final diesel engine emission performance with greatly reduced emissions handling components on the engine, such as without NOx reduction after-treatment and with only a through-flow 50% effective diesel particulate trap (DPT). They have shown this capability using multiple multi-cylinder engine tests of an Ultra High Pressure Common Rail (UHPCR) fuel system with higher than traditional levels of CEGR and an advanced injector nozzle design. The system delivered better atomization of the fuel, for more complete burn, to greatly reduce diesel particulates, while CEGR or high efficiency NOx reduction after-treatment handles the NOx. With the reduced back pressure of a traditional DPT, and with the more complete fuel burn, the system reduced levels of fuel consumption by 2.4% for similar delivery of torque and horsepower over the best Tier 4 Interim levels of fuel consumption in the diesel power industry. The challenge is to manufacture the components in high-volume production that can withstand the required higher pressure injection.

02 PETROLEUM↗
DOE OSTI2011

Successful Thrombolysis and Spasmolysis of Acute Leg Ischemia after Accidental Intra-arterial Injection of Dissolved Flunitrazepam Tablets

A 37-year-old man with known intravenous drug abuse presented in the surgical ambulatory care unit with acute leg ischemia after accidental intra-arterial injection of dissolved flunitrazepam tablets into the right femoral artery. A combination of anticoagulation, vasodilatation, and local selective and superselective thrombolysis with urokinase was performed to salvage the leg. As a result of the severe ischemia-induced pain, the patient had to be monitored over the complete therapy period on the intensive care unit with permanent administration of intravenous fluid and analgetics. We describe the presenting symptoms and the interventional technique, and we discuss the recent literature regarding the management of accidental intra-arterial injection of dissolved flunitrazepam tablets.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2012

Combined Treatment of Large Hepatocellular Carcinoma with Transcatheter Arterial Chemoembolization and Percutaneous Ethanol Injection with a Multipronged Needle: Experimental and Clinical Investigation

Purpose: This study was designed to evaluate the usefulness of percutaneous ethanol injection (PEI) with a multipronged needle for the treatment of large hepatocellular carcinoma (HCC). An experimental animal study and a clinical investigation were performed. Methods: In the experimental study, 20 ml of 99.5% ethanol was injected into porcine liver in vivo with a multipronged needle (n = 5) or a straight needle (n = 5), and the volumes of coagulation necrosis were compared. In the clinical investigation, PEI was performed in 17 patients (10 men, 7 women; mean age 73.4 {+-} 6.7 years) with single, large HCC (mean tumor diameter, 47.2 {+-} 11.5 mm; range, 32-70 mm) by using a multipronged needle. Fifteen of 17 patients received transarterial chemoembolization (TACE) before PEI. Results: The volume of coagulation in porcine liver in vivo was significantly increased with the multipronged needle compared with the straight needle (longest perpendicular diameters, 34.2 {+-} 3.6 mm Multiplication-Sign 30.2 {+-} 3.6 mm vs. 22.6 {+-} 2.5 mm Multiplication-Sign 19 {+-} 2.2 mm, respectively; P < 0.05). In the clinical trial, initial complete response (CR) of the tumor was achieved in 17 of 17 patients, 7 of whom required two PEI sessions. During the follow-up, local recurrence was detected in 4 of 17 patients at 3-19 months after the procedure, for a rate of sustained local CR of 76%. No major complication occurred. Conclusions: Use of a multipronged needle substantially increases the volume of coagulation in vivo with respect to the conventional PEI technique. Combined TACE and PEI with multipronged needles is a safe and effective option for percutaneous treatment of single, large HCC.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2016

Effects of Facet Joint Injection Reducing the Need for Percutaneous Vertebroplasty in Vertebral Compression Fractures

ObjectiveTo evaluate the effects of facet joint injection (FJI) reducing the need for percutaneous vertebroplasty (PVP) in cases of vertebral compression fracture (VCF).Materials and MethodsA total of 169 patients who were referred to the radiology department of our institution for PVP between January 2011 and December 2014 were retrospectively evaluated. The effectiveness of FJI was evaluated by the proportion of patients who cancelled PVP and who experienced reduced pain. In addition, by means of medical chart and MRI review, those clinical factors (age, sex, history of trauma, amount of injected steroids and interval days elapsed between VCF and FJI) and MR image factors (kyphosis angle, height loss, single or multiple level of VCF, burst fracture, central canal compromise, posterior element injury) that were believed to be significant for the effectiveness of FJI were statistically analysed.ResultsIn the 26 patients with FJI prior to PVP, six (23 %) patients cancelled PVP with considerable improvement in reported pain. In the 20 patients with PVP after FJI, improvement in pain after FJI was reported by six patients, resulting in a total of 12 patients (46 %) who experienced reduced pain after FJI. Clinical factors and MR image factors did not show any statistically significant difference between those groups, divided by PVP cancellation and by improvement of pain.ConclusionAfter FJI prior to PVP, about one quarter of patients cancelled PVP due to reduced pain and overall about half of the patients experienced reduced pain.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2017

Direct Injection of Blood Products Versus Gelatin Sponge as a Technique for Local Hemostasis

PurposeTo provide a method of reducing risk of minimally invasive procedures on patients with abnormal hemostasis and evaluate efficacy of direct fresh frozen plasma injection through a procedure needle tract compared to Gelfoam (gelatin sponge) administration.Materials and MethodsEighty patients with elevated international standardized ratio (INR) undergoing minimally invasive procedures using imaging guidance were selected retrospectively. Forty patients had received Gelfoam as a means of tract embolization during the procedure. The other 40 received local fresh frozen plasma (FFP) through the needle tract. The number of complications and clinically significant bleeding events were recorded. A threshold of 30 cc of blood loss after a procedure was used to identify excess bleeding.ResultsNo patients experienced clinically significant bleeding after administration of FFP. Five patients experienced postoperative drops in hemoglobin or hematomas after administration of Gelfoam.ConclusionLocal injection of blood products can reduce postprocedure bleeding in patients undergoing minimally invasive procedures and provides a safe alternative to the use of synthetic fibrin plugs.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2019

A Custom Radiopaque Thermoresponsive Chemotherapy-Loaded Hydrogel for Intratumoural Injection: An In Vitro and Ex Vivo Assessment of Imaging Characteristics and Material Properties

Purpose: Thermoresponsive hydrogels are gels which have different properties at varying temperatures. The objective of this study was to assess the material characteristics, imaging properties and chemotherapeutic drug release profile of a novel radiopaque thermoresponsive hydrogel in vitro, which is liquid at room temperature but solidifies at body temperature, to determine potential suitability for intratumoural delivery. Materials and Methods: An iodinated radiopaque thermoresponsive hydrogel was formulated using iodixanol at a range of concentrations and assessed for sol–gel transition, radiopacity and imaging using CT and US. A lead formulation containing iodixanol at a concentration of 9.22% weight by weight (w/w, g of iodixanol per g of hydrogel) was evaluated in vitro for injectability, disintegration and dual drug release of cisplatin and paclitaxel from the hydrogel formulation. Results: Radiopacity of the hydrogel increased in a concentration-dependent manner, but the highest concentration of iodixanol evaluated in this study (13.83% w/w) adversely affected the sol–gel transition of the hydrogel; therefore, 9.22% w/w iodixanol hydrogel was identified as the lead formulation. This formulation was readily visible on both CT and US. The formulation was hand injectable through a range of clinically relevant devices, had a sustained disintegration profile for up to 28 days and was able to deliver a sustained release of chemotherapeutic drug for up to 10 days. Conclusions: Favourable in vitro and ex vivo imaging and material characteristics of this thermoresponsive gel are demonstrated, suggesting potential interventional oncology applications for image-guided intratumoural delivery of sustained-release chemotherapy.

62 RADIOLOGY AND NUCLEAR MEDICINE↗
DOE OSTI2018

Effect of Hydrogen Addition on Softening and Melting Reduction Behaviors of Ferrous Burden in Gas-Injection Blast Furnace

The softening and melting reduction behaviors of ferrous burden in a gas-injection blast furnace (BF) have been investigated experimentally with the assistance of H{sub 2}. The results indicate that the initial softening temperature of the burden in the BF is lower than that in the traditional BF, while the opposite trend is observed for its melting and dripping temperatures, thus widening the softening range and narrowing the melting zone. As a result, the permeability of the stock column is apparently improved, owing to the decreased amount of the produced melt. After H{sub 2} gas is added, the thickness of the iron shell of the burden pellet increases, and the quantity of its liquid wüstite core decreases due to the higher reduction degree. The reduction rate of iron oxides is much faster than the carburization rate with the H{sub 2} addition, and the dripping behavior of the ferrous burden is determined by the carburization with a high reduction potential. After taking into account the effects of H{sub 2} addition on the iron oxide reduction rate, melt quantity, burden microstructure, and energy consumed by the gas-injection BF, it has been concluded that the optimal H{sub 2} content lies in the range between 10 and 15 pct.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Influence of Obstruction at Gas-Injection Nozzles (Number and Position) in RH Degasser Process

One of the main problems that affects Ruhrstahl-Heraeus (RH) degasser circulation rate is the obstruction of the gas-injection nozzles. This study aims to elucidate the effects of obstructions in quantity and location using a physical model that depicts 16 injection nozzles on the up-leg distributed symmetrically in 2 rings (8 nozzles/ring). We simulated six, symmetric and nonsymmetric, obstruction conditions to gas flow. The gas-flow rate was varied from 30 to 130 NL/min. The results for symmetric obstructions when the gas-flow rate is kept constant, indicates that the circulation rate in the equipment does not significantly change. However, when these obstructions are non-symmetric, the circulation rate varies drastically, even when the gas-flow rate is kept constant. The analysis of the experimental data generated from this study allowed to determine an equation for the circulation rate that takes into consideration the number and distribution of blocked nozzles.

42 ENGINEERING↗
DOE OSTI2019

Study on the Impact Characteristics of Submerged CO{sub 2} and O{sub 2} Mixed Injection (S-COMI) in EAF Steelmaking

A new type of oxygen-supplying technology was developed for electric arc furnace (EAF) steelmaking using submerged CO{sub 2} and O{sub 2} mixed injection (S-COMI). S-COMI injects O{sub 2} into the molten steel bath directly by a submerged injector installed in the furnace bed; so the metallurgical reactions can be accelerated with a high utilization ratio of oxygen. However, there has been limited research on the impact characteristics of the S-COMI submerged gas jet in EAF steelmaking. In this study, water model experiments and numerical simulations were carried out to analyze the submerged gas jet behavior, and a theoretical model was built to depict the axis trajectory of submerged gas jet in the liquid bath. The numerical results were validated against the water model experiments to show that the gas flow rate and the installed angle have a significant influence on the jet impact characteristics. The results show that as the gas flow rate increases, the horizontal and vertical penetration distances increase; as the installed angle increases, the horizontal penetration distance increases while the vertical penetration distance decreases. In addition, the erosion mechanism of the element around the submerged injector exit was studied. As the installed angle increases, the velocity component in the vertical direction increases, the fluid flow is accelerated, and the wall shear stress of the underpart of the injector element increases. Therefore, the erosion rate of the upper part of the element decreases, while that of the underpart increases.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Effect of Powder Shape and Size on Rheological, Thermal, and Segregation Properties of Low-Pressure Powder Injection Molding Feedstocks

Optimization of molding parameters at different filling stages requires that the characteristics of low-viscosity feedstocks must be properly known. In this study, the influence of the particle size (3, 7, and 12 μm) and powder morphology (gas- and water-atomized) was quantified using different feedstock formulations based on a 17-4 PH stainless steel powder, all combined with the same binder system. The specific heat capacity, viscosity, and segregation levels were assessed using a differential scanning calorimeter, a rotational rheometer, and a thermogravimetric analyzer, respectively. It was then shown that the feedstock prepared with the gas-atomized powder exhibits a higher specific heat capacity value when compared to a water-atomized powder (i.e., Cp varying from 0.6 to 0.3 J/g K, respectively). It was also shown that the feedstock viscosity profiles and the intensity of segregation both depend significantly on the powder shape and size used in the feedstock formulation. For short processing times (e.g., < 1 min spent in molten state), a feedstock formulated with coarse gas-atomized powder can be considered to be the best candidate for an injection process because its viscosity and segregation potential are relatively low (with a viscosity varying from 0.5 to 2 Pa s, and a volume fraction of powder close to 60 vol.%). Following this, the moldability index was used to predict that coarser water-atomized powder (i.e., 12 versus 7 μm) will not have a significant effect on the molding properties, and can be seen as a potential means of decreasing shrinkage during sintering without impacting the injection properties. For very long processing times, the magnitude of segregation remains insignificant for feedstock formulated with fine powder (i.e., a volume fraction of powder remaining close to 60 vol.%). However, this important gain (i.e., no segregation) comes with a significant increase in viscosity varying from 2 to 10 Pa s, resulting in a decrease in the molding properties.

36 MATERIALS SCIENCE↗