NSWC Crane Division

Heavy-ion microbeam and broadbeam data are presented for a 65 nm bulk CMOS process showing the existence of pulse quenching at normal and angular incidence for designs where the pMOS transistors are in common n-wells or isolated in separate n-wells. Experimental data and simulations show that pulse quenching is more prevalent in the common n-well design than the separate n-well design, leading to significantly reduced SET pulsewidths and SET cross-section in the common n-well design.

Digital single-event transient (SET) measurements in a bulk 65-nm process are compared to transients measured in 130-nm and 90-nm processes. The measured SET widths are shorter in a 65-nm test circuit than SETs measured in similar 90-nm and 130-nm circuits, but, when the factors affecting the SET width measurements (in particular pulse broadening and the parasitic bipolar effect) are considered, the actual SET width trends are found to be more complex. The differences in the SET widths between test circuits can be attributed in part to differences in n-well contact area. These results help explain some of the inconsistencies in SET measurements presented by various researchers over the past few years.

The synthesis and properties of Mg((x))Zn((1 - x))Fe(2)O(4) spinel ferrites as a low-toxicity alternative to the technologically significant Ni((x))Zn((1 - x))Fe(2)O(4) ferrites are reported. Ferrite nanoparticles have been formed through both the polyol and aqueous co-precipitation methods that can be readily adapted to industrial scale synthesis to satisfy the demand of a variety of commercial applications. The structure, morphology and magnetic properties of Mg((x))Zn((1 - x))Fe(2)O(4) were studied as a function of composition and particle size. Scanning electron microscopy images show particles synthesised by the aqueous co-precipitation method possess a broad size distribution (i.e. ∼ 80-120 nm) with an average diameter of the order of 100 nm ± 20 nm and could be produced in high process yields of up to 25 g l(-1). In contrast, particles synthesised by the polyol-based co-precipitation method possess a narrower size distribution with an average diameter in the 30 nm ± 5 nm range but are limited to smaller yields of ∼ 6 g l(-1). Furthermore, the polyol synthesis method was shown to control average particle size by varying the length of the glycol surfactant chain. Particles prepared by both methods are compared with respect to their phase purity, crystal structure, morphology, magnetic properties and microwave properties.

A methodology is presented for the identification of circuit total dose response mechanisms in bipolar linear microcircuits irradiated at high and low dose rates. This methodology includes manual circuit analysis, circuit simulations with SPICE using extracted device parameters, and selective irradiations of portions of the circuit using a scanning electron microscope.

The thermal instability of polymer separators severely threatens the safety characteristics of lithium-ion (Li-ion) batteries. Separators will melt, shrink, vaporize, and collapse under high temperatures, leading to internal short circuits and thermal runaway catastrophes of the cell. Therefore, the amelioration of battery safety challenges benefits from a fundamental understanding of separator behaviors under thermally abusive scenarios. This work investigates the role of separator thermal stability in modulating Li-ion cell safety performance. Three types of separators made of commercially available cellulose, trilayer polypropylene/polyethylene/polypropylene, standard polypropylene, and an in-house modified graphene-polydopamine coated separator are fabricated in custom single layer pouch cells and subjected to accelerating rate calorimeter (ARC) tests to investigate dynamic thermo-electrochemical interactions. The safety hazards of 18650 cylindrical cells assembled with different types of separators are predicted using a verified ARC computational model to compare the effects of separator heat resistance on cell-level thermal runaway risks. This study reveals the thermally robust mechanisms of diverse separator microstructures, indicating how the in-house modified graphene-polydopamine coated separator significantly enhances the safety limits of Li-ion batteries.

A high-resolution, 3D, computational fluid dynamics (CFD) model was developed and implemented for simulating the heat and gas generation during thermal runaway failure of an 18650 Li-ion battery cell. The model accounts for volumetric gas generation within the active material of the cell and for gas flow through the jellyroll, into the headspace regions, through the safety vent, and out into the surrounding air space. The simulation captures the key features of the oven test, including: self-heating from decomposition reactions, initial venting (i.e. blowdown), temperature decrease due to evaporative cooling, thermal runaway, a second venting event associated with thermal runaway, and cooldown. The highly detailed geometric model of the safety vent allowed for new insight into the physics of venting during thermal runaway. Secondary flows, including ring vortices, counter-rotating vortex pairs, and corner vortices, were found to increase the rate of mixing of the vented gases with the surrounding air. The simulation was compared to previously reported experimental results and found to have good qualitative agreement of jet flow direction. The present thermal abuse model forms the basis for future studies to consider the role of gas impingement heat transfer and gas combustion in full battery pack propagating failures.

In this study three conventional bipolar linear microcircuits, the LM101A operational amplifier, the LM124 quad operational amplifier, and the LM139 quad voltage comparator, were irradiated at high dose rate, elevated temperature and the results compared to low dose rate, room temperature response. While the high dose rate degradation at elevated temperature was greater than the degradation at room temperature, it was not as great as the degradation at low dose rate. Therefore, a hardness assurance test using elevated temperature irradiation at higher dose rates, designed to bound the very low dose rate response, will probably have to include overtest.

Ion mobility spectrometry-mass spectrometry (IMS-MS) techniques are used to study the general effects of phosphorylation on peptide structure. Cross sections for a library of 66 singly phosphorylated peptide ions from 33 pairs of positional isomers, and unmodified analogues were measured. Intrinsic size parameters (ISPs) derived from these measurements yield calculated collision cross sections for 85% of these phosphopeptide sequences that are within ±2.5% of experimental values. The average ISP for the phosphoryl group (0.64 ± 0.05) suggests that in general this moiety forms intramolecular interactions with the neighboring residues and peptide backbone, resulting in relatively compact structures. We assess the capability of ion mobility to separate positional isomers (i.e., peptide sequences that differ only in the location of the modification) and find that more than half of the isomeric pairs have >1% difference in collision cross section. Phosphorylation is also found to influence populations of structures that differ in the cis/trans orientation of Xaa-Pro peptide bonds. Several sequences with phosphorylated Ser or Thr residues located N-terminally adjacent to Pro residues show fewer conformations compared to the unmodified sequences.

Abstract Swab touch spray ionization mass spectrometry, an ambient ionization technique, has been applied to the analysis of six explosives from various surfaces including glass, metal, Teflon, plastic, human hands and three types of gloves (nitrile, vinyl and latex). A swab, attached to a metallic handle, was used to sample explosive residues and acted as the ion source. The explosives, 1,3,5‐trinitro‐1,3,5‐triazinane (RDX), 1,3,5,7‐tetranitro‐1,3,5,7‐tetrazocane (HMX), and 2,2‐bis[(nitrooxy)methyl]propane‐1,3‐diyl dinitrate (PETN) had an absolute limit of detection of 10 ng from all the surfaces except for PETN from the nitrile gloves (limit of detection 100 ng). Sodium perchlorate, 2‐methyl‐1,3,5‐trinitrobenzene (TNT) and tetra‐butylammonium perchlorate had limits of detection of 100 pg, 10 pg, and 1 pg, respectively from all surfaces. This study demonstrates the feasibility of swab touch spray ionization mass spectrometry for detection of a wide array of explosives from a variety of forensically applicable surfaces with disposable, commercial, tamperproof and individually‐wrapped conductive swabs without complicated/lengthy sample preparations or extractions.

Heavy-ion broadbeam results from a 90 nm process are presented for five inverter chains with varying n-well contact schemes. Results show that inverters with the smallest percentage of n-well contact area within an n-well produced the longest and most frequent single-event transients (SETs). As the percentage of n-well area contacted increases above 2%, the pulse width and number of SETs levels-off. A result indicating an optimized percentage of n-well area contacted can be calculated that minimizes the pulse width and number of SETs in a digital circuit.

Approaches to the adequate homogenization of optical metamaterials are becoming more and more complex, primarily due to an increased understanding of the role of asymmetric electrical and magnetic responses, in addition to the nonlocal effects of the surrounding medium, even in the simplest case of plane-wave illumination. The current trend in developing such advanced homogenization descriptions often relies on utilizing bianisotropic models as a base on top of which novel optical characterization techniques can be built. In this paper, we first briefly review general principles for developing a bianisotropic homogenization approach. Second, we present several examples validating and illustrating our approach using single-period passive and active optical metamaterials. We also show that the substrate may have a significant effect on the bianisotropic characteristics of otherwise symmetric passive and active metamaterials.

Understanding the emergence, co-evolution, and convergence of science and technology (S&T) areas offers competitive intelligence for researchers, managers, policy makers, and others. This paper presents new funding, publication, and scholarly network metrics and visualizations that were validated via expert surveys. The metrics and visualizations exemplify the emergence and convergence of three areas of strategic interest: artificial intelligence (AI), robotics, and internet of things (IoT) over the last 20 years (1998-2017). For 32,716 publications and 4,497 NSF awards, we identify their topical coverage (using the UCSD map of science), evolving co-author networks, and increasing convergence. The results support data-driven decision making when setting proper research and development (R&D) priorities; developing future S&T investment strategies; or performing effective research program assessment.

High temperature gases released through the safety vent of a lithium-ion cell during a thermal runaway event contain flammable components that, if ignited, can increase the risk of thermal runaway propagation to other cells in a multi-cell pack configuration. Computational fluid dynamics (CFD) simulations of flow through detailed geometric models of four vent-activated commercial 18650 lithium-ion cell caps were conducted using two turbulence modeling approaches: Reynolds-averaged Navier-Stokes (RANS) and scale-resolving simulations (SRS). The RANS method was compared with independent experiments of discharge coefficient through the cap across a range of pressure ratios and then used to investigate the ensemble-averaged flow field for the four caps. At high pressure ratios, choked flow occurs either at the current collector plate when flow through the current collector plate is more restrictive or the positive terminal vent holes when flow through the current collector plate is less restrictive. Turbulent mixing occurred within the vent cap assembly, in the jets emerging from the vent holes, and in recirculating zones directly above the vent cap assembly. The global maximum turbulent viscosity ratio ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:msub><mml:mi>μ</mml:mi><mml:mi>T</mml:mi></mml:msub><mml:mo>/</mml:mo><mml:mi>μ</mml:mi></mml:mrow></mml:math> ) of the MTI, LG MJ1, K2, and LG M36 caps at pressure ratio of P 1 /P 2 = 7 were 4,575, 3,360, 3,855, and 2,993, respectively. SRS and RANS simulations showed that both velocity magnitude and fluctuating velocity magnitude were lower for vent holes which are obstructed by the burst disk. SRS showed high levels of fluctuating velocity in the jets, up to 48.5% of the global maximum velocity. The present CFD models and the resulting insights provide the groundwork for future studies to investigate how jet structure and turbulence levels influence combustion and heat transfer in propagating thermal runaway scenarios.

Ubiquitin confined within nanodroplets was irradiated with a variable-power CO2 laser. Mass spectrometry analysis shows evidence for a protein "melting"-like transition within droplets prior to solvent evaporation and ion formation. Ion mobility spectrometry reveals that structures associated with early steps of denaturation are trapped because of short droplet lifetimes.

The role of net positive oxide trapped charge and surface recombination velocity on excess base current in bipolar junction transistors (BJTs) is identified. The effects of the two types of damage can be detected by plotting the excess base current versus base-emitter voltage. Differences and similarities between ionizing-radiation-induced and hot electron-induced degradation are discussed.

For the first time, double-pulse-single-event transients (DPSETs) are observed during heavy-ion broad beam testing. The transients are generated in a serially connected string of inverters and measured with an autonomous on-chip SET pulse-width measurement circuit. Three-dimensional mixed-mode technology computer aided design (TCAD) simulations show that DPSETs are the result of multiple inverters being upset by a single ion strike.

Consecutive write operations performed on a Samsung NAND flash memory are shown to significantly increase the total ionizing dose level at which data corruption occurs. Consequences of multiple consecutive write operations are discussed as well as the mechanisms at work. Elevated temperature exposure and page location within a block of the memory are shown to have significant effects on the amount of data corruption observed. The hardness assurance implications of these effects are discussed.

This article presents an analytical model for enhancement-mode GaN devices for high-power application. The model is developed specifically for a GaN gate injection transistor (GIT) device in which a positive threshold voltage is achieved by inserting a p-type GaN layer underneath the gate electrode that is incorporated in the analytical model presented in this article. In addition, the operation of enhancement-mode GaN transistors for high-power application is significantly impacted by carrier spill-over at higher gate bias. Therefore, this model also includes the impact of carrier spill-over by considering parallel conduction in the barrier layer adjacent to the two-dimensional electron gas (2DEG) channel of the transistor and the degradation of mobility and charge density on device operation. In addition, due to high power dissipation and low thermal conductivity of GaN material, the device performance degrades at high temperature. In this article, high-temperature operation of the device is modeled by taking into account the temperature exponents of the device parameters that vary with temperature. At high current density, the device shows significant self-heating effect, which is also modeled using a similar approach. The overall model is compared with the experimentally measured data that shows an excellent match.

Isomerizations of the retinal chromophore were investigated using the IMS-IMS technique. Four different structural features of the chromophore were observed, isolated, excited collisionally, and the resulting isomer and fragment distributions were measured. By establishing the threshold activation voltages for isomerization for each of the reaction pathways, and by measuring the threshold activation voltage for fragmentation, the relative energies of the isomers as well as the energy barriers for isomerization were determined. The energy barrier for a single cis-trans isomerization is (0.64±0.05) eV, which is significantly lower than that observed for the reaction within opsin proteins.

A novel RHBD technique that exploits charge sharing is implemented in the single-ended gain stage of a folded-cascode operational amplifier to mitigate single-event transients (SETs). The efficacy of the technique is demonstrated via two-photon laser experiments. Using settling time as the primary metric for SET severity, the proposed layout technique achieves sensitive area reductions ranging from 41% to 95% with an overall area penalty of less than 1%.