Total dose effects on negative voltage regulator

Abstract Functional failure at low dose level (4 Krad(Si)) on voltage regulators (LM137) from different manufacturers are analysed. Dose rate effects on parts hardness are evaluated, showing that lowering the dose rate degrade more the ICs in the range 55 rad(Si)/s-0,s rad(Si)/s A failure mechanism is proposed, mainly based on circuit analysis, voltage contrast measurements, local irradiation and local electrical measurements with probe station. A spice simulation was performed, providing quantitative informations on the degradation. In the light of such a failure analysis and dose rate Pagure (Saclay, France) panoramic Cobalt60 source of 20 000 Ci located few kilometres away from VBlizy plant. Remote testing were performed in VBlizy using LTS 2020 automatic tester from Analog Devices, Digital Signal Analyser DSA601 from Tekmnic and HP4172 from Helwett Packard. Delay between irradiation and remote testing is kept below one hour. Local irradiation are performed using scanning transmission electron microscope JEOL JSM840 with electron energy up to 40 Kev. Contrast voltage potential measurement were carried out using a IDS Shlumberger tester. Probing measurements were performed using Wentworth probe station MP900 and HP4145 from Helwett Packard. effects, practical implications on radiation assurance are discussed. FAILURE DESCRIPTION I. INTRODUCTION Bipolar linear ICs are usually known as quite hard parts regarding Total Dose effects, with typical dose hardness in the range 50 to 100 Krad(Si). Such a postulate comes mainly from the relative intrinsic high hardness of bipolar transistor and passive devices. The problem is that bipolar transistors and passive elements used in linear ICs are not similar to the well known elemental structures. Because of integration constraint and in order to minimise the number of mask steps during IC processing, PNP transistors are often lateral ones. Such a type of transistor is already known as Total Ionizing Dose (TID) sensitiveIl1. When using such a sensitive structure in critical function of linear IC, loss of functionality can be foreseen, as already predicted by Johnston 2. In this paper, we will focus on negative voltage regulator (LM137 type) from 4 different manufacturers. We will analyse the degradation mode, based on different test methods. LM137 is a three terminal adjustable output negative voltage regulator. Reference voltage of -1.250V can be delivered for input voltage (referred to output voltage) ranging from -4.2% to -41.25V. The 137 circuit, shown in figure 1, consists in start up circuit, intemal comparator, band gap reference, power output stage and prowtion circuitry. ILEXPERIMENTAL PROCEDUR

On the Nature of the Frontal Zone of the Choctawhatchee Bay Plume in the Gulf of Mexico

River plumes often feature turbulent processes in the frontal zone and interfacial region at base of the plume, which ultimately impact spreading and mixing rates with the ambient coastal ocean. The degree to which these processes govern overall plume mixing is yet to be quantified with microstructure observations. A field campaign was conducted in a river plume in the northeast Gulf of Mexico in December 2013, in order to assess mixing processes that could potentially impact transport and dispersion of surface material near coastal regions. Current velocity, density, and Turbulent Kinetic Energy Values, ε, were obtained using an Acoustic Doppler Current Profiler (ADCP), a Conductivity Temperature Depth (CTD) profiler, a Vertical Microstructure Profiler (VMP), and two Acoustic Doppler Velocimeters (ADVs). The frontal region contained ε values on the order of 10−5 m2 s−3, which were markedly larger than in the ambient water beneath (O 10−9 m2s−3). An energetic wake of moderate ε values (O 10−6 m2 s−3) was observed trailing the frontal edge. The interfacial region of an interior section of the plume featured opposing horizontal velocities and a ε value on the order of 10−6 m2 s−3. A simplified mixing budget was used under significant assumptions to compare contributions from wind, tides, and frontal regions of the plume. The results from this order of magnitude analysis indicated that frontal processes (59%) dominated in overall mixing. This emphasizes the importance of adequate parameterization of river plume frontal processes in coastal predictive models

Ocean convergence and the dispersion of flotsam

Floating oil, plastics, and marine organisms are continually redistributed by ocean surface currents. Prediction of their resulting distribution on the surface is a fundamental, long-standing, and practically important problem. The dominant paradigm is dispersion within the dynamical context of a nondivergent flow: objects initially close together will on average spread apart but the area of surface patches of material does not change. Although this paradigm is likely valid at mesoscales, larger than 100 km in horizontal scale, recent theoretical studies of submesoscales (less than ∼10 km) predict strong surface convergences and downwelling associated with horizontal density fronts and cyclonic vortices. Here we show that such structures can dramatically concentrate floating material. More than half of an array of ∼200 surface drifters covering ∼20 × 20 km2 converged into a 60 × 60 m region within a week, a factor of more than 105 decrease in area, before slowly dispersing. As predicted, the convergence occurred at density fronts and with cyclonic vorticity. A zipperlike structure may play an important role. Cyclonic vorticity and vertical velocity reached 0.001 s−1 and 0.01 ms−1, respectively, which is much larger than usually inferred. This suggests a paradigm in which nearby objects form submesoscale clusters, and these clusters then spread apart. Together, these effects set both the overall extent and the finescale texture of a patch of floating material. Material concentrated at submesoscale convergences can create unique communities of organisms, amplify impacts of toxic material, and create opportunities to more efficiently recover such material

Ocean convergence and the dispersion of flotsam

Floating oil, plastics, and marine organisms are continually redistributed by ocean surface currents. Prediction of their resulting distribution on the surface is a fundamental, long-standing, and practically important problem. The dominant paradigm is dispersion within the dynamical context of a nondivergent flow: objects initially close together will on average spread apart but the area of surface patches of material does not change. Although this paradigm is likely valid at mesoscales, larger than 100 km in horizontal scale, recent theoretical studies of submesoscales (less than ∼10 km) predict strong surface convergences and downwelling associated with horizontal density fronts and cyclonic vortices. Here we show that such structures can dramatically concentrate floating material. More than half of an array of ∼200 surface drifters covering ∼20 × 20 km2 converged into a 60 × 60 m region within a week, a factor of more than 105 decrease in area, before slowly dispersing. As predicted, the convergence occurred at density fronts and with cyclonic vorticity. A zipperlike structure may play an important role. Cyclonic vorticity and vertical velocity reached 0.001 s−1 and 0.01 ms−1, respectively, which is much larger than usually inferred. This suggests a paradigm in which nearby objects form submesoscale clusters, and these clusters then spread apart. Together, these effects set both the overall extent and the finescale texture of a patch of floating material. Material concentrated at submesoscale convergences can create unique communities of organisms, amplify impacts of toxic material, and create opportunities to more efficiently recover such material

Thin ice, deep snow and surface flooding in Kotzebue Sound: landfast ice mass balance during two anomalously warm winters and implications for marine mammals and subsistence hunting

The inaugural data from the first systematic program of sea ice observations in Kotzebue Sound, Alaska, in 2018 coincided with the first winter in living memory when the Sound was not choked with ice. The following winter of 2018-19 was even warmer and characterized by even less ice. Here we discuss the mass balance of landfast ice near Kotzebue (Qikiktagruk) during these two anomalously warm winters. We use in-situ observations and a 1-D thermodynamic model to address three research questions developed in partnership with an Indigenous Advisory Council. In doing so, we improve our understanding of connections between landfast ice mass balance, marine mammals, and subsistence hunting. Specifically, we show: i) Ice growth stopped unusually early due to strong vertical ocean heat flux, which also likely contributed to early start to bearded seal hunting; ii) Unusually thin ice contributed to widespread surface flooding. The associated snow ice formation partly offset the reduced ice growth, but the flooding likely had a negative impact on ringed seal habitat; iii) Sea ice near Kotzebue during the winters of 2017-18 and 2018-19 was likely the thinnest since at least 1945, driven by a combination of warm air temperatures and a persistent ocean heat flux.

Codes and Data for "The Radiative and Geometric Properties of Melting First-Year Sea Ice", pre-submission

In May 2019, a series of observations of sea ice radiative properties were made over Kotzebue Sound, Alaska during the advanced stages of the Springtime melt. This archive contains the codes and data required to reproduce figures in a manuscript that will be submitted to the Journal of Geophysical Research: Oceans (a pre-submission draft PDF is included within the archive)

The impact of rain on ocean surface waves and currents: Supporting information

Observational data and MATLAB codes used in the analysis described in "The impact of rain on ocean surface waves and currents" by N. J. M. Laxague & C. J. Zappa, Geophysical Research Letters (2020). Data contents include time series of wind speed, rain rate, ocean surface wave spectrum, and near-surface current

Data for: Observations of mean and wave orbital flows in the ocean's upper centimetres (version 1)

Observations of near-surface ocean currents, collected in 2008 in the Santa Barbara Channel. Archive contains a brief 'readme' file and two central MATLAB routines. The routines will grab the included raw data and make use of a small library of additional codes to reproduce key figures in "Observations of mean and wave orbital flows in the ocean's upper centimetres", Laxague & Zappa (2019), Journal of Fluid Mechanics. See the note below for more information

Codes and Data for "The Radiative and Geometric Properties of Melting First-Year Sea Ice", v2

In May 2019, a series of observations of sea ice radiative properties were made over Kotzebue Sound, Alaska during the advanced stages of the Springtime melt. This archive contains the codes and data required to reproduce figures in a manuscript that has been accepted at The Cryosphere (EGUSPHERE-2023-2541)