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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,657 records · Page 92
All sourcesNASA NTRSDOE OSTI
DOE OSTI2016

Surface nanopattern formation due to current-induced homoepitaxial nanowire edge instability

Physical nanopatterning based on a precise control of macroscopic forcing is an essential tool of nanoscale science and technology. Using an externally applied electric field as the macroscopic force, we report here a computational study on the formation of surface nanopatterns consisting of single-layer homoepitaxial islands as a result of a morphological instability that can occur under edge electromigration conditions on the straight edge of a single-layer nanowire grown epitaxially on a crystalline substrate. Direct dynamical simulations based on a model that has been validated experimentally for the Ag/Ag system show that the current-induced nanowire edge instability causes the breakup of the nanowire and leads to the formation of uniformly distributed islands, arranged in linear or V-shaped arrays, which are uniformly sized with nanoscale dimensions. The simulation results are supported by linear stability theory and demonstrate that the geometrical features of the island patterns and the island sizes can be controlled precisely by controlling the electric field direction with respect to the nanowire axis and the electric field strength. Our findings have important implications for developing physical nanopatterning approaches toward enabling future nanofabrication technologies.

36 MATERIALS SCIENCE↗
DOE OSTI2026

Degradation Dynamics of Perovskite Solar Cells Under Fixed Reverse-Current Injection

Previous studies of reverse-bias stability in perovskite solar cells have focused primarily on voltage-controlled tests. Here we instead investigate perovskite solar cell degradation under well-defined, constant reverse-current stress. We show that the choice of hole-transport layer dictates the dominant degradation pathway: cells using thick poly(triphenylamine) (PTAA) layers can tolerate high reverse bias but quickly undergo catastrophic breakdown under fixed reverse current near their one-sun maximum power-point. In contrast, cells modified with phosphonic-acid interface layer MeO-2PACz, with poorer indium-doped tin oxide (ITO) coverage compared to PTAA, exhibit gradual and recoverable degradation under certain stress and recovery conditions. For MeO-2PACz devices, degradation increases with both current magnitude and duration. Importantly, when normalized by injected charge (current times duration), lower currents applied over longer times cause more degradation than higher currents over shorter periods. Here, combining electrical measurements with spatially resolved photoluminescence imaging, our observations support an ion- and charge-mediated interfacial electrochemical degradation mode.

Degradation↗
DOE OSTI2012

INL Control System Situational Awareness Technology Annual Report 2012

The overall goal of this project is to develop an interoperable set of tools to provide a comprehensive, consistent implementation of cyber security and overall situational awareness of control and sensor network implementations. The operation and interoperability of these tools will fill voids in current technological offerings and address issues that remain an impediment to the security of control systems. This report provides an FY 2012 update on the Sophia, Mesh Mapper, Intelligent Cyber Sensor, and Data Fusion projects with respect to the year-two tasks and annual reporting requirements of the INL Control System Situational Awareness Technology report (July 2010).

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2024

Introduction to Grid Forming Inverters: A Key to Transforming our Power Grid [Slides]

A grid-forming (GFM) inverter-based resource (IBR) controls maintain an internal voltage phasor that is constant or nearly constant in the sub-transient to transient time frame. This definition means that the GFM IBR will nearly immediately respond to changes in the external system and attempt to maintain IBR control during challenging network conditions to maintain grid stability. In GFM IBR, the voltage phasor is controlled to maintain synchronism with other devices in the grid while regulating the active and reactive power appropriately to support the grid. This contrasts with conventional GFL IBR controls wherein immediately after a disturbance (0-5 cycles), within the normal operating range of voltage, the output current phasor magnitude and angle remain unchanged, and the current phasor begins changing only within the transient time frame (tens of cycles) to strictly control the active and reactive power being injected into the network. This presentation gives an introduction to GFM IBR and presents the current state of the art in this area.

24 POWER TRANSMISSION AND DISTRIBUTION↗
DOE OSTI2021

Prokaryotic viruses impact functional microorganisms in nutrient removal and carbon cycle in wastewater treatment plants

As one of the largest biotechnological applications, activated sludge (AS) systems in wastewater treatment plants (WWTPs) harbor enormous viruses, with 10-1,000-fold higher concentrations than in natural environments. However, the compositional variation and host-connections of AS viruses remain poorly explored. Here, we report a catalogue of ~50,000 prokaryotic viruses from six WWTPs, increasing the number of described viral species of AS by 23-fold, and showing the very high viral diversity which is largely unknown (98.4-99.6% of total viral contigs). Most viral genera are represented in more than one AS system with 53 identified across all. Viral infection widely spans 8 archaeal and 58 bacterial phyla, linking viruses with aerobic/anaerobic heterotrophs, and other functional microorganisms controlling nitrogen/phosphorous removal. Notably, Mycobacterium, notorious for causing AS foaming, is associated with 402 viral genera. Our findings expand the current AS virus catalogue and provide reference for the phage treatment to control undesired microorganisms in WWTPs.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2025

Flexible Operation of Microgrids Through Operator-Configurable Microgrid Controllers

Microgrids are becoming critical assets in power distribution systems. This is partly due to the resiliency and reliability challenges faced by power distribution systems in the last decade and partly due to the increased integration of distributed energy resource assets, such as solar photovoltaic. This increased need for microgrids has created a multitude of needs for microgrid controllers. Most microgrid controllers in the past decade have been uniquely programmed or custom programmed to meet the needs of a specific microgrid. Currently, IEEE standards aim to integrate the needs and capabilities of microgrid controllers under a unified umbrella. But the standards do not recommend necessary or appropriate software development practices for microgrid controllers. In addition, the programmable nature and maintenance of controllers are also key characteristics that fall outside the coverage of the standards. In this paper, we present the best software practices that utility engineers and microgrid operators should consider in the microgrid software platform. This paper can be used as an information document for developing documentation of controller requirements and assessing microgrid controller requirements.

Banshee microgrid↗
DOE OSTI2019

The evolution of a super-swarm of foot-and-mouth disease virus in cattle

Foot-and-mouth disease (FMD) is a highly contagious viral disease that severely impacts global food security and is one of the greatest constraints on international trade of animal products. Extensive viral population diversity and rapid, continuous mutation of circulating FMD viruses (FMDVs) pose significant obstacles to the control and ultimate eradication of this important transboundary pathogen. The current study investigated mechanisms contributing to within-host evolution of FMDV in a natural host species (cattle). Specifically, vaccinated and non-vaccinated cattle were infected with FMDV under controlled, experimental conditions and subsequently sampled for up to 35 days to monitor viral genomic changes as related to phases of disease and experimental cohorts. Consensus-level genomic changes across the entire FMDV coding region were characterized through three previously defined stages of infection: early, transitional, and persistent. The overall conclusion was that viral evolution occurred via a combination of two mechanisms: emergence of full-genomic minority haplotypes from within the inoculum super-swarm, and concurrent continuous point mutations. Phylogenetic analysis indicated that individuals were infected with multiple distinct haplogroups that were pre-existent within the ancestral inoculum used to infect all animals. Multiple shifts of dominant viral haplotype took place during the early and transitional phases of infection, whereas few shifts occurred during persistent infection. Overall, this work suggests that the establishment of the carrier state is not associated with specific viral genomic characteristics. These insights into FMDV population dynamics have important implications for virus sampling methodology and molecular epidemiology.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2024

Controlling the Phase Transformation of Alumina for Enhanced Stability and Catalytic Properties

Current transition alumina catalysts require the presence of significant amounts of toxic, environmentally deleterious dopants for their stabilization. Herein, we report a simple and novel strategy to engineer transition aluminas to withstand aging temperatures up to 1200 °C without inducing the transformation to low-surface-area α-Al 2 O 3 and without requiring dopants. By judiciously optimizing the abundance of dominant facets and the interparticle distance, we can control the temperature of the phase transformation from θ-Al 2 O 3 to α-Al 2 O 3 and the specific surface sites on the latter. These specific surface sites provide favorable interactions with supported metal catalysts, leading to improved metal dispersion and greatly enhanced catalytic activity for hydrocarbon oxidation. Further, the results presented herein not only provide molecular-level insights into the critical factors causing deactivation and phase transformation of aluminas but also pave the way for the development of catalysts with improved activity for catalytic hydrocarbon oxidation.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2017

Light and temperature effects on miR156 transgenic switchgrass flowering: A simulated latitudinal study

The control of flowering in perennial grasses is an important trait, especially among biofuel feedstocks. Lignocellulosic biomass may be increased commensurate with decreased or delayed flowering as the plant allocates energy for stems and leaves harvested for bioenergy at the end of the growing season. For transgenic feedstocks, such as switchgrass ( Panicum virgatum L. ) grown in its geographic center of distribution, it is foreseeable that regulators may require greatly decreased gene flow frequencies to enable commercialization. Transgenic switchgrass with various overexpression levels of a rice microRNA gene, miR156, when grown in field conditions, holds promise for decreased flowering, yielding high biomass, and altered cell wall traits, which renders it as a potential crossing partner for further breeding with switchgrass lines for decreased recalcitrance. In the current research, we simulated a latitudinal cline in controlled growth chamber experiments for various individual sites from the tropics to cool-temperate conditions which included weekly average high and low temperatures and day lengths over the switchgrass growing season for each simulated site: Guayaquil, Ecuador; Laredo, Texas, USA; and Brattleboro, Vermont, USA. Flowering and reproduction among transgenic lines with low (T-14 and T-35)--tomoderate (T-27 and T-37) overexpression of miR156 were assessed. Lower simulated latitudes (higher temperatures with low-variant day length) and long growing seasons promoted flowering of the miR156 transgenic switchgrass lines. Tropical conditions rescued the flowering phenotype in all transgenic lines except T-27. Higher numbers of plants in lines T-35 and T-37 and the controls produced panicles, which also occurred earlier in the study as temperatures increased and day length decreased. Line T-14 was the exception as more clonal replicates flowered in the cool-temperate (Vermont) conditions. Increased biomass was found in transgenic lines T-35 and T-37 in tropical conditions. No difference in biomass was found in subtropical (Texas) chambers, and two lines (T-14 and T-35) produced less biomass than the control in cool-emperate conditions. Our findings suggest that switchgrass plants engineered to overexpress miR156 for delayed flowering to promote bioconfinement and biomass production may be used for plant breeding at tropical sites.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2024

Validation of prediction capability of operating space for plasma initiation in MAST-U

DYON is a plasma initiation modelling code that solves the differential equation system of the full circuit equations (plasma current, active coil currents and eddy currents in full passive structures) and 0D global energy and particle balance equations (Kim 2022 Nucl. Fusion 62 126012). In order to test the capability of the full electromagnetic plasma initiation model to predict individual discharges in experiments and thus the operating space in the device, a dedicated experimental database was built in MAST-U by scanning the prefilled gas pressure p 0 and the induced loop voltage V loop . In the experimental operating space of p 0 and V loop the lower and the upper limits of p 0 are determined by the plasma breakdown failure and the plasma burn-through failure, respectively. The lower limit of V loop is determined by the plasma burn-through failure. By directly reading the control room data used in each discharge (i.e. currents in the solenoid, poloidal field coils, and toroidal field coils, p 0 , and gas puffing rate), the full electromagnetic DYON consistently predicted the failed breakdown, failed burn-through, and successful plasma initiation discharges in the experimental database, demonstrating its capability to predict the operating space for inductive plasma initiation. The Paschen curve calculated with the effective connection length in MAST-U indicates a much higher p 0 required for plasma breakdown than the experimental data, indicating that individual field line evaluation is necessary to calculate the quantitative requirements for Townsend breakdown. The demonstration in this paper shows that the full electromagnetic DYON could be a useful simulation tool to assess the feasibility of inductive plasma initiation and to optimise operating scenarios in future devices.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2018

Hydrostatic pressure incubation affects barrier properties of mammary epithelial cell monolayers, in vitro

Highlights: • A modified Ussing chamber was used to apply physiological pressure on HC11 cells. • Pressure was applied to simulate accumulation of milk in the mammary gland. • Dependence of differentiation state and transcellular transport was observed. • Effects on barrier function were attributed to tight junction protein expression. During lactation, accumulation of milk in mammary glands (MG) causes hydrostatic pressure (HP) and concentration of bioactive compounds. Previously, a changed expression of tight junction (TJ) proteins was observed in mice MGs by accumulation of milk, in vivo. The TJ primarily determines the integrity of the MG epithelium. The present study questioned whether HP alone can affect the TJ in a mammary epithelial cell model, in vitro. Therefore, monolayers of HC11, a mammary epithelial cell line, were mounted into modified Ussing chambers and incubated with 10 kPa bilateral HP for 4 h. Short circuit current and transepithelial resistance were recorded and compared to controls, and TJ proteins were analyzed by Western blotting and immunofluorescent staining. In our first approach HC11 cells could withstand the pressure incubation and a downregulation of occludin was observed. In a second approach, using prolactin- and dexamethasone-induced cells, a decrease of short circuit current was observed, beginning after 2 h of incubation. With the addition of 1 mM barium chloride to the bathing solution the decrease could be blocked temporarily. On molecular level an upregulation of ZO-1 could be observed in hormone-induced cells, which was downregulated after the incubation with barium chloride. In conclusion, bilateral HP incubation affects mammary epithelial monolayers, in vitro. Both, the reduction of short circuit current and the change in TJ proteins may be interpreted as physiological requirements for lactation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2014

Unreviewed Disposal Question Evaluation: Impact of New Information since 2008 PA on Current Low-Level Solid Waste Operations

Solid low-level waste disposal operations are controlled in part by an E-Area Low-Level Waste Facility (ELLWF) Performance Assessment (PA) that was completed by the Savannah River National Laboratory (SRNL) in 2008 (WSRC 2008). Since this baseline analysis, new information pertinent to disposal operations has been identified as a natural outcome of ongoing PA maintenance activities and continuous improvement in model simulation techniques (Flach 2013). An Unreviewed Disposal Question (UDQ) Screening (Attachment 1) has been initiated regarding the continued ability of the ELLWF to meet Department of Energy (DOE) Order 435.1 performance objectives in light of new PA items and data identified since completion of the original UDQ Evaluation (UDQE). The present UDQE assesses the ability of Solid Waste (SW) to meet performance objectives by estimating the influence of new information items on a recent sum-of-fractions (SOF) snapshot for each currently active E-Area low-level waste disposal unit. A final SOF, as impacted by this new information, is projected based on the assumptions that the current disposal limits, Waste Information Tracking System (WITS) administrative controls, and waste stream composition remain unchanged through disposal unit operational closure (Year 2025). Revision 1 of this UDQE addresses the following new PA items and data identified since completion of the original UDQE report in 2013: New K d values for iodine, radium and uranium; Elimination of cellulose degradation product (CDP) factors; Updated radionuclide data; Changes in transport behavior of mobile radionuclides; Potential delay in interim closure beyond 2025; and Component-in-grout (CIG) plume interaction correction. Consideration of new information relative to the 2008 PA baseline generally indicates greater confidence that PA performance objectives will be met than indicated by current SOF metrics. For SLIT9, the previous prohibition of non-crushable containers in revision 0 of this UDQE has rendered the projected final SOF for SLIT9 less than the WITS Admin Limit. With respect to future disposal unit operations in the East Slit Trench Group, consideration of new information for Slit Trench#14 (SLIT14) reduced the current SOF for the limiting All-Pathways 200-1000 year period (AP2) by an order of magnitude and by one quarter for the Beta-Gamma 12-100 year period (BG2) pathway. On the balance, updates to K{sub d} values and dose factors and elimination of CDP factors (generally favorable) more than compensated for the detrimental impact of a more rigorous treatment of plume dispersion. These observations suggest that future operations in the East Slit Trench Group can be conducted with higher confidence using current inventory limits, and that limits could be increased if desired for future low-level waste disposal units. The same general conclusion applies to future ST’s in the West Slit Trench Group based on the Impacted Final SOFs for existing ST’s in that area.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2021

Chemical compositions, pharmacological activities, quality control studies of Erycibes plants, and the development of their substitutes

Erycibes are members of the Convolvulaceae family, including more than 10 species worldwide that are distributed in tropical Asia. Some Erycibes species have long been used as traditional remedies for rheumatoid arthritis, fever, hepatitis, and liver injury in China and Thailand. A total of 152 compounds from Erycibes plants have been isolated and identified, categorized as flavonoids, coumarins, quinic acid derivatives, lignans, and alkaloids. Coumarins are the characteristic and active constituents of this species, including scopoletin and scopolin. Modern pharmacological studies have shown that the extracts and bioactive components of Erycibes plants exhibit several biological activities, including antiinflammatory, analgesic, hepatoprotective, anti‐gout, antitumor, antioxidation, and other therapeutic effects. However, in recent years, due to destructive exploitation and utilization, some Erycibes plants' natural resources have become rare or endangered. Developing substitutes is a strategy to alleviate the pressure on those endangered medicinal plant resources. To provide a scientific basis for the development and protection of those threatened Erycibes species, this review summarized the current status of the chemical compositions, pharmacological activities, quality control studies, and the development of substitutes for Erycibes plants. In particular, the rationale for use of Porana sinensis currently on the market is discussed.

Peng, Yu↗
DOE OSTI2013

Hanford Waste Transfer Planning and Control - 13465

Hanford tank waste cleanup requires efficient use of double-shell tank space to support single-shell tank retrievals and future waste feed delivery to the Waste Treatment and Immobilization Plant (WTP). Every waste transfer, including single-shell tank retrievals and evaporator campaign, is evaluated via the Waste Transfer Compatibility Program for compliance with safety basis, environmental compliance, operational limits and controls to enhance future waste treatment. Mixed radioactive and hazardous wastes are stored at the Hanford Site on an interim basis until they can be treated, as necessary, for final disposal. Implementation of the Tank Farms Waste Transfer Compatibility Program helps to ensure continued safe and prudent storage and handling of these wastes within the Tank Farms Facility. The Tank Farms Waste Transfer Compatibility Program is a Safety Management Program that is a formal process for evaluating waste transfers and chemical additions through the preparation of documented Waste Compatibility Assessments (WCA). The primary purpose of the program is to ensure that sufficient controls are in place to prevent the formation of incompatible mixtures as the result of waste transfer operations. The program defines a consistent means of evaluating compliance with certain administrative controls, safety, operational, regulatory, and programmatic criteria and specifies considerations necessary to assess waste transfers and chemical additions. Current operations are most limited by staying within compliance with the safety basis controls to prevent flammable gas build up in the tank headspace. The depth of solids, the depth of supernatant, the total waste depth and the waste temperature are monitored and controlled to stay within the Compatibility Program rules. Also, transfer planning includes a preliminary evaluation against the Compatibility Program to assure that operating plans will comply with the Waste Transfer Compatibility Program. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2014

An Updated Methodology for Enhancing Risk Monitors with Integrated Equipment Condition Assessment

Small modular reactors (SMRs) generally include reactors with electric output of ~350 MWe or less (this cutoff varies somewhat but is substantially less than full-size plant output of 700 MWe or more). Advanced SMRs (AdvSMRs) refer to a specific class of SMRs and are based on modularization of advanced reactor concepts. Enhancing affordability of AdvSMRs will be critical to ensuring wider deployment, as AdvSMRs suffer from loss of economies of scale inherent in small reactors when compared to large (~greater than 600 MWe output) reactors and the controllable day-to-day costs of AdvSMRs will be dominated by operation and maintenance (O&M) costs. Technologies that help characterize real-time risk are important for controlling O&M costs. Risk monitors are used in current nuclear power plants to provide a point-in-time estimate of the system risk given the current plant configuration (e.g., equipment availability, operational regime, and environmental conditions). However, current risk monitors are unable to support the capability requirements listed above as they do not take into account plant-specific normal, abnormal, and deteriorating states of active components and systems. This report documents technology developments towards enhancing risk monitors that, if integrated with supervisory plant control systems, can provide the capability requirements listed and meet the goals of controlling O&M costs. The report describes research results on augmenting an initial methodology for enhanced risk monitors that integrate real-time information about equipment condition and POF into risk monitors. Methods to propagate uncertainty through the enhanced risk monitor are evaluated. Available data to quantify the level of uncertainty and the POF of key components are examined for their relevance, and a status update of this data evaluation is described. Finally, we describe potential targets for developing new risk metrics that may be useful for studying trade-offs for economic operation while maintaining adequate safety margins.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2013

Technical Report on Preliminary Methodology for Enhancing Risk Monitors with Integrated Equipment Condition Assessment

Small modular reactors (SMRs) generally include reactors with electric output of ~350 MWe or less (this cutoff varies somewhat but is substantially less than full-size plant output of 700 MWe or more). Advanced SMRs (AdvSMRs) refer to a specific class of SMRs and are based on modularization of advanced reactor concepts. AdvSMRs may provide a longer-term alternative to traditional light-water reactors (LWRs) and SMRs based on integral pressurized water reactor concepts currently being considered. Enhancing affordability of AdvSMRs will be critical to ensuring wider deployment. AdvSMRs suffer from loss of economies of scale inherent in small reactors when compared to large (~greater than 600 MWe output) reactors. Some of this loss can be recovered through reduced capital costs through smaller size, fewer components, modular fabrication processes, and the opportunity for modular construction. However, the controllable day-to-day costs of AdvSMRs will be dominated by operation and maintenance (O&M) costs. Technologies that help characterize real-time risk are important for controlling O&M costs. Risk monitors are used in current nuclear power plants to provide a point-in-time estimate of the system risk given the current plant configuration (e.g., equipment availability, operational regime, and environmental conditions). However, current risk monitors are unable to support the capability requirements listed above as they do not take into account plant-specific normal, abnormal, and deteriorating states of active components and systems. This report documents technology developments that are a step towards enhancing risk monitors that, if integrated with supervisory plant control systems, can provide the capability requirements listed and meet the goals of controlling O&M costs. The report describes research results from an initial methodology for enhanced risk monitors by integrating real-time information about equipment condition and POF into risk monitors.

advanced small modular reactor↗
DOE OSTI2025

Feasibility of fusion plasma burn control via real-time, sub-divertor neutral gas isotopic and compositional analysis

The ability to provide fusion burn control without requiring physical access through the first wall and fuel breeding blankets, would be vital for any future, magnetically confined fusion power reactor. A multi-sensor, fusion fuel cycle exhaust, neutral gas analysis system on JET, capable of delivering real time data, and accessing only the sub-divertor region, provides an excellent example of such capability. Optimized for and operated during the deuterium–tritium experimental campaigns 2 and 3 (DTE2, DTE3), it is proving valuable for planning to explore fusion reactor burn control in ITER with a comparable diagnostic system called the Diagnostic Residual Gas Analyzer (DRGA). This paper aims to show feasibility of developing model-based controllers for ITER and next generation, reactor-relevant devices, by building both on the empirical experience in JET-DTE2, and on the already emerging experience on developing such models specifically for ITER. The paper begins with a specific use-case from JET-DTE2, pertaining to the observed sensitivity of the fusion neutron yield on the concentration of isotopic helium-3 ( 3 He), with data from one of the high-performance DT shots exhibited with emphasis on the 3 He measurement via the sub-divertor. Then, a first model is developed and then explored with simulations that aim to discover how well the controllers in the model react to either insufficient levels of 3 He or excessive levels of 3 He. The simulations then explore potential impact from a delay in the measurement (or the response) that would be comparable to the ∼1 s, conductance limited response for the ITER DRGA system, currently in its final design. The simulations show that control is feasible, and that its effectiveness is not significantly impacted by such delay.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2015

Surface potential distribution and airflow performance of different air-exposed electrode plasma actuators at different alternating current/direct current voltages

Asymmetric surface dielectric barrier discharge (SDBD) plasma actuators have been intensely studied for a number of years due to their potential applications for aerodynamic control. In this paper, four types of actuators with different configurations of exposed electrode are proposed. The SDBD actuators investigated are driven by dual-power supply, referred to as a fixed AC high voltage and an adjustable DC bias. The effects of the electrode structures on the dielectric surface potential distribution, the electric wind velocity, and the mean thrust production are studied, and the dominative factors of airflow acceleration behavior are revealed. The results have shown that the actions of the SDBD actuator are mainly dependent on the geometry of the exposed electrode. Besides, the surface potential distribution can effectively affect the airflow acceleration behavior. With the application of an appropriate additional DC bias, the surface potential will be modified. As a result, the performance of the electric wind produced by a single SDBD can be significantly improved. In addition, the work also illustrates that the actuators with more negative surface potential present better mechanical performance.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗