Effects of internal yaw-vectoring devices on the static performance of a pitch-vectoring nonaxisymmetric convergent-divergent nozzle

NASA Technical Reports Server (NTRS)

Asbury, Scott C.

1993-01-01

An investigation was conducted in the static test facility of the Langley 16-Foot Transonic Tunnel to evaluate the internal performance of a nonaxisymmetric convergent divergent nozzle designed to have simultaneous pitch and yaw thrust vectoring capability. This concept utilized divergent flap deflection for thrust vectoring in the pitch plane and flow-turning deflectors installed within the divergent flaps for yaw thrust vectoring. Modifications consisting of reducing the sidewall length and deflecting the sidewall outboard were investigated as means to increase yaw-vectoring performance. This investigation studied the effects of multiaxis (pitch and yaw) thrust vectoring on nozzle internal performance characteristics. All tests were conducted with no external flow, and nozzle pressure ratio was varied from 2.0 to approximately 13.0. The results indicate that this nozzle concept can successfully generate multiaxis thrust vectoring. Deflection of the divergent flaps produced resultant pitch vector angles that, although dependent on nozzle pressure ratio, were nearly equal to the geometric pitch vector angle. Losses in resultant thrust due to pitch vectoring were small or negligible. The yaw deflectors produced resultant yaw vector angles up to 21 degrees that were controllable by varying yaw deflector rotation. However, yaw deflector rotation resulted in significant losses in thrust ratios and, in some cases, nozzle discharge coefficient. Either of the sidewall modifications generally reduced these losses and increased maximum resultant yaw vector angle. During multiaxis (simultaneous pitch and yaw) thrust vectoring, little or no cross coupling between the thrust vectoring processes was observed.

Static Performance of a Wing-Mounted Thrust Reverser Concept

NASA Technical Reports Server (NTRS)

Asbury, Scott C.; Yetter, Jeffrey A.

1998-01-01

An experimental investigation was conducted in the Jet-Exit Test Facility at NASA Langley Research Center to study the static aerodynamic performance of a wing-mounted thrust reverser concept applicable to subsonic transport aircraft. This innovative engine powered thrust reverser system is designed to utilize wing-mounted flow deflectors to produce aircraft deceleration forces. Testing was conducted using a 7.9%-scale exhaust system model with a fan-to-core bypass ratio of approximately 9.0, a supercritical left-hand wing section attached via a pylon, and wing-mounted flow deflectors attached to the wing section. Geometric variations of key design parameters investigated for the wing-mounted thrust reverser concept included flow deflector angle and chord length, deflector edge fences, and the yaw mount angle of the deflector system (normal to the engine centerline or parallel to the wing trailing edge). All tests were conducted with no external flow and high pressure air was used to simulate core and fan engine exhaust flows. Test results indicate that the wing-mounted thrust reverser concept can achieve overall thrust reverser effectiveness levels competitive with (parallel mount), or better than (normal mount) a conventional cascade thrust reverser system. By removing the thrust reverser system from the nacelle, the wing-mounted concept offers the nacelle designer more options for improving nacelle aero dynamics and propulsion-airframe integration, simplifying nacelle structural designs, reducing nacelle weight, and improving engine maintenance access.

Double wedge prism based beam deflector for precise laser beam steering

NASA Astrophysics Data System (ADS)

Tyszka, Krzysztof; Dobosz, Marek; Bilaszewski, Tomasz

2018-02-01

Aiming to increase laser beam pointing stability required in interferometric measurements, we designed a laser beam deflector intended for active laser beam stabilization systems. The design is based on two wedge-prisms: the deflecting wedge driven by a tilting piezo-platform and the fixed wedge to compensate initial beam deflection. Our design allows linear beam steering, independently in the horizontal or vertical direction, with resolution of less than 1 μrad in a range of more than 100 μrad, and no initial deflection of the beam. Moreover, the ratio of the output beam deflection angle and the wedge tilt angle is less than 0.1; therefore, the noise influence is significantly reduced in comparison to standard mirror-based deflectors. The theoretical analyses support the designing process and can serve as a guide to wedge-prism selection. The experimental results are in agreement with theory and confirm the advantages of the presented double wedge system.

Modeling and measurement of a micro-optic beam deflector

NASA Technical Reports Server (NTRS)

Milster, Tom D.; Wong, J. Nan

1992-01-01

The use is studied of a unity-magnification micro-optic beam deflector. The defelector consists of two arrays of positively powered lenslets. The lenslets on each array are arranged in a square grid. Design criteria are based on usefulness in optical data storage devices. The deflector is designed to operate over a + or - 1.6 range of deflection angles. Modeling results are compared with interferometric analysis of the wavefront from a single lenslet pair. The results indicate that the device is nearly diffraction limited, but there are substantial wavefront errors at the edges and corners of the lenslets.

The MAVEN Solar Wind Electron Analyzer

NASA Astrophysics Data System (ADS)

Mitchell, D. L.; Mazelle, C.; Sauvaud, J.-A.; Thocaven, J.-J.; Rouzaud, J.; Fedorov, A.; Rouger, P.; Toublanc, D.; Taylor, E.; Gordon, D.; Robinson, M.; Heavner, S.; Turin, P.; Diaz-Aguado, M.; Curtis, D. W.; Lin, R. P.; Jakosky, B. M.

2016-04-01

The MAVEN Solar Wind Electron Analyzer (SWEA) is a symmetric hemispheric electrostatic analyzer with deflectors that is designed to measure the energy and angular distributions of 3-4600-eV electrons in the Mars environment. This energy range is important for impact ionization of planetary atmospheric species, and encompasses the solar wind core and halo populations, shock-energized electrons, auroral electrons, and ionospheric primary photoelectrons. The instrument is mounted at the end of a 1.5-meter boom to provide a clear field of view that spans nearly 80 % of the sky with ˜20° resolution. With an energy resolution of 17 % (Δ E/E), SWEA readily distinguishes electrons of solar wind and ionospheric origin. Combined with a 2-second measurement cadence and on-board real-time pitch angle mapping, SWEA determines magnetic topology with high (˜8-km) spatial resolution, so that local measurements of the plasma and magnetic field can be placed into global context.

Transfer matrix calculation for ion optical elements using real fields

NASA Astrophysics Data System (ADS)

Mishra, P. M.; Blaum, K.; George, S.; Grieser, M.; Wolf, A.

2018-03-01

With the increasing importance of ion storage rings and traps in low energy physics experiments, an efficient transport of ion species from the ion source area to the experimental setup becomes essential. Some available, powerful software packages rely on transfer matrix calculations in order to compute the ion trajectory through the ion-optical beamline systems of high complexity. With analytical approaches, so far the transfer matrices are documented only for a few ideal ion optical elements. Here we describe an approach (using beam tracking calculations) to determine the transfer matrix for any individual electrostatic or magnetostatic ion optical element. We verify the procedure by considering the well-known cases and then apply it to derive the transfer matrix of a 90-degree electrostatic quadrupole deflector including its realistic geometry and fringe fields. A transfer line consisting of a quadrupole deflector and a quadrupole doublet is considered, where the results from the standard first order transfer matrix based ion optical simulation program implementing the derived transfer matrix is compared with the real field beam tracking simulations.

Effect of deflector curvature on hydrodynamic performances of a double-slotted cambered otter-board

NASA Astrophysics Data System (ADS)

WANG, Lei; Wang, Lu Min; Shi, Jian Gao; Yu, Wen Wen; Qi, Guang Rui; Zhang, Xun; Zhang, Rong Jun; Zhang, Tian Shu

2018-06-01

The effect of deflector curvature on hydrodynamic performances of a double-slotted cambered otter-board was investigated using engineering models in a wind tunnel. Four different curvature (0.06,0.09, 0.12 and 0.15) were evaluated at a wind speed of 28 m/s. Parameters measured included: drag coefficient Cx, lift coefficient Cy, pitch moment coefficient Cm, center of pressure coefficient Cp , over a range of angle of attack (0° to 70°). These coefficients were used in analyzing the differences in the performance among the four otter-board models. Results showed that the maximum lift coefficient Cy of the otter-board model with the curvature (0.06) of two deflectors was highest (2.020 at °=55°). The maximum Cy/Cx of the otter-board with the curvature (0.12) of two deflectors was highest (3.655 at °=22.5°). A comparative analysis of Cm and Cp showed that the stability of otter-board model with the curvature (0.12) of two deflectors is better in pitch, and the stability of otter-board model with the curvature (0.06) of two deflectors is better in roll. The findings of this study can offer useful reference data for the structural optimization of otter-boards for trawling.

Experimental investigation of the inlet detector configuration variation in the flow field at Mach 1.9

NASA Technical Reports Server (NTRS)

Hwang, Kyu C.; Tiwari, Surrendra N.; Miley, Stanley J.

1995-01-01

In recent years, active research has been conducted to study the technological feasibility of supersonic laminar flow control on the wing of the High Speed Civil Transport (HSCT). For this study, the F-16XL has been chosen due to its highly swept crank wing planform that closely resembles the HSCT configurations. During flights, it is discovered that the shock wave generated from the aircraft inlet introduces disturbances on the wing where the data acquisition is conducted. The flow field about a supersonic inlet is characterized by a complex three dimensional pattern of shock waves generated by the geometrical configuration of a deflector and a cowl lip. Hence, in this study, experimental method is employed to investigate the effects of the variation of deflector configuration on the flow field, and consequently, the possibility of diverting the incoming shock-disturbances away from the test section. In the present experiments, a model composed of a simple circular tube with a triangular deflector is designed to study the deflector length and the deflector base width variation in the flow field. Experimental results indicate that the lowest external pressure ratio is observed at the junction where the deflector lip and the inlet cowl lip merge. Also, it is noted that the external pressure ratio, the internal pressure ratio, the coefficient of spillage drag, and the shock standoff distance decrease as the deflector length increases. In addition, the Redefined Total Pressure Recovery Ratio (RTPRR) increases with an increase in the deflector length. Results from the study of the effect of the deflector's base width variation on the flow field indicate that the lowest external pressure ratio is observed at the junction between the inlet cowl lip and the deflector lip. As the base width of the deflector increases, the external pressure ratio at 0 rotation increases, whereas the external pressure ratio at 180 rotation decreases. In addition, the internal pressure ratio and the coefficient of spillage drag decrease as the base width of the deflector increases. However, RTPRR and shock standoff distance increase as the base width increases. In conclusion, as deflector dimensions vary, distinctive patterns in the pressure variation around the inlet deflector are observed. With an increase in the deflector length and base width, the magnitude of shock-disturbances are weakened due to a decrease in the external pressure ratio. Also, as the deflector length and base width increase, a smaller bow shock angle is formed. Therefore, the inlet shock wave formation would be significantly altered, and consequently, shock disturbances on the wing test section can be avoided through appropriately designing the deflector.

Noise tests of a model engine-over-the-wing STOL configuration using a multijet nozzle with deflector

NASA Technical Reports Server (NTRS)

Olsen, W. A.; Friedman, R.

1973-01-01

Noise data were obtained with a small scale model stationary STOL configuration that used an eight lobe mixer nozzle with deflector mounted above a 32-cm-chord wing section. The factors varied to determine their effect upon the noise were wing flap angle, nozzle shape, nozzle location, deflector configuration, and jet velocity. The noise from the mixer nozzle model was compared to the noise from a model using a circular nozzle of the same area. The mixer nozzle model was quieter at the low to middle frequencies, while the circular nozzle was quieter at high frequencies. The perceived noise level (PNL) was calculated for an aircraft 10 times larger than the model. The PNL at 500 feet for the mixer nozzle turned out to be within 1 db of the PNL for the circular nozzle. For some configurations at highly directional broadband noise, which could be eliminated by changes in nozzle and/or deflector location, occurred below the wing.

Bluff-body drag reduction using a deflector

NASA Astrophysics Data System (ADS)

Fourrié, Grégoire; Keirsbulck, Laurent; Labraga, Larbi; Gilliéron, Patrick

2011-02-01

A passive flow control on a generic car model was experimentally studied. This control consists of a deflector placed on the upper edge of the model rear window. The study was carried out in a wind tunnel at Reynolds numbers based on the model height of 3.1 × 105 and 7.7 × 105. The flow was investigated via standard and stereoscopic particle image velocimetry, Kiel pressure probes and surface flow visualization. The aerodynamic drag was measured using an external balance and calculated using a wake survey method. Drag reductions up to 9% were obtained depending on the deflector angle. The deflector increases the separated region on the rear window. The results show that when this separated region is wide enough, it disrupts the development of the counter-rotating longitudinal vortices appearing on the lateral edges of the rear window. The current study suggests that flow control on such geometries should consider all the flow structures that contribute to the model wake flow.

Studies of Beam Expansion and Distributed Bragg Reflector Lasers for Fiber Optics and Optical Signal Processing.

DTIC Science & Technology

1981-03-03

described theory and experiments on the DBR laser and on the use of the Distributed Bragg Deflector ( DBD ) to act as a grating bean expander. The DBD is a...and telescope. 9 .\\pplications requiring more power can use the DBD as a power combiner for several laser stripes, as shown in Fig. 3. In design...Bragg deflector ( DBD ). This device consists of a corrugated waveguide, whose grating is slanted at an angle 6 with respect to the incident beam. The

Design of An Improved Miniature Ion Neutral Mass Spectrometer for NASA Applications

NASA Technical Reports Server (NTRS)

Swaminathan, Viji K.; Alig, Roger C.

1997-01-01

The ion optics of NASA's Ion Neutral Mass Spectrometer (INMS) sensor was simulated with three dimensional models of the open source, the quadrupole deflector, the exit lens system and the quadrupole mass analyzer to design more compact models with lower weight. Comparison of calculated transmission with experimental results shows good agreement. Transmission analyses with varying geometrical parameters and voltages throw light on possible ways of reducing the size of the sensor. Trajectories of ions of mass 1-99 amu were simulated to analyze and optimize transmission. Analysis of open source transmission with varying angle of attack shows that the angular acceptance can be considerably increased by programming the voltages on the ion trap/ collimator. Analysis of transmission sensitivity to voltages and misalignments of the quadrupole deflector rods indicate that increased transmission is possible with a geometrically asymmetrical deflector and a deflector can be designed with much lower sensitivities of transmission. Bringing the disks closer together can decrease the size of the quadrupole deflector and also increase transmission. The exit lens system can be redesigned to be smaller by eliminating at least one electrode entirely without loss of transmission. Ceramic materials were investigated to find suitable candidates for use in the construction of lighter weight mass spectrometer. A high-sensitivity, high-resolution portable gas chromatograph mass spectrometer with a mass range of 2-700 amu has been built and will be commercialized in Phase 3.

Small scale model static acoustic investigation of hybrid high lift systems combining upper surface blowing with the internally blown flap

NASA Technical Reports Server (NTRS)

Cole, T. W.; Rathburn, E. A.

1974-01-01

A static acoustic and propulsion test of a small radius Jacobs-Hurkamp and a large radius Flex Flap combined with four upper surface blowing (USB) nozzles was performed. Nozzle force and flow data, flap trailing edge total pressure survey data, and acoustic data were obtained. Jacobs-Hurkamp flap surface pressure data, flow visualization photographs, and spoiler acoustic data from the limited mid-year tests are reported. A pressure ratio range of 1.2 to 1.5 was investigated for the USB nozzles and for the auxiliary blowing slots. The acoustic data were scaled to a four-engine STOL airplane of roughly 110,000 kilograms or 50,000 pounds gross weight, corresponding to a model scale of approximately 0.2 for the nozzles without deflector. The model nozzle scale is actually reduced to about .17 with deflector although all results in this report assume 0.2 scale factor. Trailing edge pressure surveys indicated that poor flow attachment was obtained even at large flow impingement angles unless a nozzle deflector plate was used. Good attachment was obtained with the aspect ratio four nozzle with deflector, confirming the small scale wind tunnel tests.

Study and Construction of Electrostatic Biprisms Useful in Corpuscular Optics; ETUDE ET REALISATION DE BIPRISMES ELECTROSTATIQUES UTILISABLES EN OPTIQUE CORPUSCULAIRE

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

Septier, A.

1960-03-01

In the simultaneous injection of two beams identical except in direction in an FFAG cyclotron, two beams of equal intensity and energy are needed. The two beams can be produced either by alternating the direction of a single beam by very short, rectangular, high-voltage pulses fed to a deflector, or by chopping the beam with a static apparatus. The second method was investigated because of its simplicity. The principles and properties of the electrostatic biprism are presented. Three cases are then considered: a wire stretched between two plates, a grid between two plates, and a plate between two flat conductors.more » (T.R.H.)« less

Assessment at full scale of nozzle/wing geometry effects on OTW aero-acoustic characteristics. [short takeoff aircraft noise

NASA Technical Reports Server (NTRS)

Groesbeck, D.; Vonglahn, U.

1979-01-01

The effects on acoustic characteristics of nozzle type and location on a wing for STOL engine over-the-wing configurations are assessed at full scale on the basis of model-scale data. Three types of nozzle configurations are evaluated: a circular nozzle with external deflector mounted above the wing, a slot nozzle with external deflector mounted on the wing and a slot nozzle mounted on the wing. Nozzle exhaust plane locations with respect to the wing leading edge are varied from 10 to 46 percent chord (flaps retracted) with flap angles of 20 (takeoff altitude) and 60 (approach attitude). Perceived noise levels (PNL) are calculated as a function of flyover distance at 152 m altitude. From these plots, static EPNL values, defined as flyover relative noise levels, are calculated and plotted as a function of lift and thrust ratios. From such plots the acoustic benefits attributable to variations in nozzle/deflector/wing geometry at full scale are assessed for equal aerodynamic performance.

Ensuring a reliable satellite

NASA Astrophysics Data System (ADS)

Johnson, Charles E.; Persinger, Randy R.; Lemon, James J.; Volkert, Keith J.

Comprehensive testing and monitoring approaches have been formulated and implemented for Intelsat VI, which is the largest commercial satellite in service. An account is given of the ground test program from unit level through launch site activities, giving attention to the test data handling system. Test methods unique to Intelsat VI encompass near-field anechoic chamber antenna measurements, offloading 1-g deployment of solar cell and deflector antennas, and electrostatic discharge measurements. The problems accruing to the sheer size of this spacecraft are stressed.

A study for the installation of the TEXT heavy-ion beam probe on DIII-D

NASA Astrophysics Data System (ADS)

Edmonds, P. H.; Solano, E. R.; Bravenec, R. V.; Wootton, A. J.; Schoch, P. M.; Crowley, T. P.; Hickok, R. L.; West, W. P.; Leuer, J.; Anderson, P.

1997-01-01

An assessment of the feasibility of installing the TEXT 2 MeV heavy-ion beam probe on the DIII-D tokamak has been completed. Detailed drawings of the machine cross section were imported into the CAD application AutoCAD. A set of programs written in AutoLisp were used to generate trajectories. Displays of the accessible cross section of the plasma, scan lines for the entire range of primary beam energy and injection angle ranges, and sample-volume dimensions can be rapidly generated. Because of the large deflection between the primary input beam and the emergent secondary beam, either the analyzer needs to be tracked over a ±20° angle or secondary poloidal deflector plates need to be installed at the exit port. Toroidal deflector plates will be installed at both the injection and exit ports to compensate for toroidal displacements and deflections. The sample volumes generated by this procedure are within a few centimeters of the locations derived from a full three-dimensional calculation.

Small-scale test program to develop a more efficient swivel nozzle thrust deflector for V/STOL lift/cruise engines

NASA Technical Reports Server (NTRS)

Schlundt, D. W.

1976-01-01

The installed performance degradation of a swivel nozzle thrust deflector system obtained during increased vectoring angles of a large-scale test program was investigated and improved. Small-scale models were used to generate performance data for analyzing selected swivel nozzle configurations. A single-swivel nozzle design model with five different nozzle configurations and a twin-swivel nozzle design model, scaled to 0.15 size of the large-scale test hardware, were statically tested at low exhaust pressure ratios of 1.4, 1.3, 1.2, and 1.1 and vectored at four nozzle positions from 0 deg cruise through 90 deg vertical used for the VTOL mode.

Electro-optic deflectors deliver advantages over acousto-optical deflectors in a high resolution, ultra-fast force-clamp optical trap.

PubMed

Woody, Michael S; Capitanio, Marco; Ostap, E Michael; Goldman, Yale E

2018-04-30

We characterized experimental artifacts arising from the non-linear response of acousto-optical deflectors (AODs) in an ultra-fast force-clamp optical trap and have shown that using electro-optical deflectors (EODs) instead eliminates these artifacts. We give an example of the effects of these artifacts in our ultra-fast force clamp studies of the interaction of myosin with actin filaments. The experimental setup, based on the concept of Capitanio et al. [Nat. Methods 9, 1013-1019 (2012)] utilizes a bead-actin-bead dumbbell held in two force-clamped optical traps which apply a load to the dumbbell to move it at a constant velocity. When myosin binds to actin, the filament motion stops quickly as the total force from the optical traps is transferred to the actomyosin attachment. We found that in our setup, AODs were unsuitable for beam steering due to non-linear variations in beam intensity and deflection angle as a function of driving frequency, likely caused by low-amplitude standing acoustic waves in the deflectors. These aberrations caused instability in the force feedback loops leading to artifactual jumps in the trap position. We demonstrate that beam steering with EODs improves the performance of our instrument. Combining the superior beam-steering capability of the EODs, force acquisition via back-focal-plane interferometry, and dual high-speed FPGA-based feedback loops, we apply precise and constant loads to study the dynamics of interactions between actin and myosin. The same concept applies to studies of other biomolecular interactions.

Design challenges of EO polymer based leaky waveguide deflector for 40 Gs/s all-optical analog-to-digital converters

NASA Astrophysics Data System (ADS)

Hadjloum, Massinissa; El Gibari, Mohammed; Li, Hongwu; Daryoush, Afshin S.

2016-08-01

Design challenges and performance optimization of an all-optical analog-to-digital converter (AOADC) is presented here. The paper addresses both microwave and optical design of a leaky waveguide optical deflector using electro-optic (E-O) polymer. The optical deflector converts magnitude variation of the applied RF voltage into variation of deflection angle out of a leaky waveguide optical beam using the linear E-O effect (Pockels effect) as part of the E-O polymer based optical waveguide. This variation of deflection angle as result of the applied RF signal is then quantized using optical windows followed by an array of high-speed photodetectors. We optimized the leakage coefficient of the leaky waveguide and its physical length to achieve the best trade-off between bandwidth and the deflected optical beam resolution, by improving the phase velocity matching between lightwave and microwave on one hand and using pre-emphasis technique to compensate for the RF signal attenuation on the other hand. In addition, for ease of access from both optical and RF perspective, a via-hole less broad bandwidth transition is designed between coplanar pads and coupled microstrip (CPW-CMS) driving electrodes. With the best reported E-O coefficient of 350 pm/V, the designed E-O deflector should allow an AOADC operating over 44 giga-samples-per-seconds with an estimated effective resolution of 6.5 bits on RF signals with Nyquist bandwidth of 22 GHz. The overall DC power consumption of all components used in this AOADC is of order of 4 W and is dominated by power consumption in the power amplifier to generate a 20 V RF voltage in 50 Ohm system. A higher sampling rate can be achieved at similar bits of resolution by interleaving a number of this elementary AOADC at the expense of a higher power consumption.

Three types of planar structure microspring electro-thermal actuators with insulating beam constraints

NASA Astrophysics Data System (ADS)

Luo, J. K.; Flewitt, A. J.; Spearing, S. M.; Fleck, N. A.; Milne, W. I.

2005-08-01

A new concept of using an electrically insulating beam as a constraint is proposed to construct planar spring-like electro-thermal actuators with large displacements. On the basis of this concept, three types of microspring actuators with multi-chevron structures and constraint beams are introduced. The constraint beams in one type (the spring) of these devices are horizontally positioned to restrict the expansion of the active arms in the x-direction, and to produce a displacement in the y-direction only. In the other two types of actuators (the deflector and the contractor), the constraint beams are positioned parallel to the active arms. When the constraint beams are on the inner side of the active arms, the actuator produces an outward deflection in the y-direction. When they are on the outside of the active arms, the actuator produces an inward contraction. Finite-element analysis was used to model the performances. The simulation shows that the displacements of these microspring actuators are all proportional to the number of the chevron sections in series, thus achieving superior displacements to alternative actuators. The displacement of a spring actuator strongly depends on the beam angle, and decreases with increasing the beam angle, the deflector is insensitive to the beam angle, while the displacement of a contractor actuator increases with the beam angle.

Assessment at full scale of nozzle/wing geometry effects on OTW aeroacoustic characteristics. [Over The Wing STOL engine configurations

NASA Technical Reports Server (NTRS)

Groesbeck, D.; Von Glahn, U.

1979-01-01

The effects on acoustic characteristics of nozzle type and location on a wing for STOL engine over-the-wing configurations are assessed at full scale on the basis of model-scale data. Three types of nozzle configurations are evaluated: a circular nozzle with external deflector mounted above the wing, a slot nozzle with external deflector mounted on the wing and a slot nozzle mounted on the wing. Nozzle exhaust plane locations with respect to the wing leading edge are varied from 10 to 46 percent chord (flaps retracted) with flap angles of 20 deg (take-off attitude) and 60 deg (approach attitude). Perceived noise levels (PNL) are calculated as a function of flyover distance at 152 m altitude. From these plots, static EPNL values, defined as flyover relative noise levels, are calculated and plotted as a function of lift and thrust ratios. From such plots the acoustic benefits attributable to variations in nozzle/deflector/wing geometry at full scale are assessed for equal aerodynamic performance.

Exploring the influence of transfer channels on fusion reactions: The case of 40 Ca + 58,64 Ni

DOE PAGES

Bourgin, D.; Courtin, S.; Haas, F.; ...

2015-01-29

Fusion cross sections have been measured in the 40Ca + 58Ni and 40Ca + 64Ni systems at beam energies ranging from E lab = 104.75 MeV to 153.5 MeV using the Laboratori Nazionali di Legnaro electrostatic deflector. Distributions of barriers have been extracted from the experimental data. Preliminary coupled channel calculations were performed and hints of effects of neutron transfers on the fusion below the barrier in the 40Ca + 64Ni are discussed.

Field Modeling, Symplectic Tracking, and Spin Decoherence for EDM and Muon $$g\\textrm{-}2$$ Lattices

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

Valetov, Eremey Vladimirovich

2017-01-01

While the first particle accelerators were electrostatic machines, and several electrostatic storage rings were subsequently commissioned and operated, electrostatic storage rings pose a number of challenges. Unlike motion in the magnetic field, where particle energy remains constant, particle energy generally changes in electrostatic elements. Conservation of energy in an electrostatic element is, in practice, only approximate, and it requires careful and accurate design, manufacturing, installation, and operational use. Electrostatic deflectors require relatively high electrostatic fields, tend to introduce nonlinear aberrations of all orders, and are more challenging to manufacture than homogeneous magnetic dipoles. Accordingly, magnetic storage rings are overwhelmingly prevalent.more » The search for electric dipole moments (EDMs) of fundamental particles is of key importance in the study of C and CP violations and their sources. C and CP violations are part of the Sakharov conditions that explain the matter–antimatter asymmetry in the universe. Determining the source of CP violations would provide valuable empirical insight for beyond-Standard-Model physics. EDMs of fundamental particles have not to this date been experimentally observed. The search for fundamental particle EDMs has narrowed the target search region; however, an EDM signal is yet to be discovered. In 2008, Brookhaven National Laboratory (BNL) had proposed the frozen spin (FS) concept for the search of a deuteron EDM. The FS concept envisions launching deuterons through a storage ring with combined electrostatic and magnetic fields. The electrostatic and magnetic fields are in a proportion that would, without an EDM, freeze the deuteron’s spin along its momentum as the deuteron moves around the lattice. The radial electrostatic field would result in a torque on the spin vector, proportional to a deuteron EDM, rotating the spin vector out of the midplane.« less

Electro-Optic Diffraction Grating Tuned Laser.

DTIC Science & Technology

The patent concerns an electro - optic diffraction grating tuned laser comprising a laser medium, output mirror, retro-reflective grating and an electro - optic diffraction grating beam deflector positioned between the laser medium and the reflective diffraction grating. An optional angle multiplier may be used between the electro - optic diffraction grating and the reflective grating.

A study for the installation of the TEXT heavy-ion beam probe on DIII-D

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

Edmonds, P.H.; Solano, E.R.; Bravenec, R.V.

1997-01-01

An assessment of the feasibility of installing the TEXT 2 MeV heavy-ion beam probe on the DIII-D tokamak has been completed. Detailed drawings of the machine cross section were imported into the CAD application AutoCAD. A set of programs written in AutoLisp were used to generate trajectories. Displays of the accessible cross section of the plasma, scan lines for the entire range of primary beam energy and injection angle ranges, and sample{endash}volume dimensions can be rapidly generated. Because of the large deflection between the primary input beam and the emergent secondary beam, either the analyzer needs to be tracked overmore » a {plus_minus}20{degree} angle or secondary poloidal deflector plates need to be installed at the exit port. Toroidal deflector plates will be installed at both the injection and exit ports to compensate for toroidal displacements and deflections. The sample volumes generated by this procedure are within a few centimeters of the locations derived from a full three-dimensional calculation.{copyright} {ital 1997 American Institute of Physics.}« less

Particle beam injector system and method

DOEpatents

Guethlein, Gary

2013-06-18

Methods and devices enable coupling of a charged particle beam to a radio frequency quadrupole accelerator. Coupling of the charged particle beam is accomplished, at least in-part, by relying on of sensitivity of the input phase space acceptance of the radio frequency quadrupole to the angle of the input charged particle beam. A first electric field across a beam deflector deflects the particle beam at an angle that is beyond the acceptance angle of the radio frequency quadrupole. By momentarily reversing or reducing the established electric field, a narrow portion of the charged particle beam is deflected at an angle within the acceptance angle of the radio frequency quadrupole. In another configuration, beam is directed at an angle within the acceptance angle of the radio frequency quadrupole by the first electric field and is deflected beyond the acceptance angle of the radio frequency quadrupole due to the second electric field.

Forward velocity effects on fan noise and the suppression characteristics of advanced inlets as measured in the NASA-Ames 40 by 80 foot wind tunnel

NASA Technical Reports Server (NTRS)

Moore, M. T.

1980-01-01

Forward velocity effects on the forward radiated fan noise and on the suppression characteristics of three advanced inlets relative to a baseline cylindrical inlet were measured in the NASA Ames Research Center 40 x 80 foot Wind Tunnel. A modified JT15D turbofan engine in a quiet nacelle was the source of fan noise; the advanced inlets were a Conventional Takeoff/Landing (CTOL) hybrid inlet, a Short Takeoff/Landing (STOL) hybrid inlet, and a treated deflector inlet. Also measured were the static to flight effects on the fan noise of canting the baseline inlet 4 deg downward to simulate typical wing mounted turbofan engines. The CTOL hybrid inlet suppressed the high tip speed fan noise as much as 18 PNdB on a 61 m (200 ft) sideline scaled to a CF6 size engine while the STOL hybrid inlet suppressed the low tip speed fan noise as much as 13 PNdB on a 61 m (200 ft) sideline scaled to a OCSEE size engine. The deflector inlet suppressed the high tip speed fan noise as much as 13 PNdB at 61 m (200 ft) overhead scaled to a CF6 size engine. No significant changes in fan noise suppression for the CTOL and STOL hybrid inlets occurred for forward velocity changes above 21 m/s (68 ft/s) or for angle of attack changes up to 15 deg. However, changes in both forward velocity and angle of attack changed the deflector inlet noise unpredictably due to the asymmetry of the inlet flow field into the fan.

Single-channel stereoscopic ophthalmology microscope based on TRD

NASA Astrophysics Data System (ADS)

Radfar, Edalat; Park, Jihoon; Lee, Sangyeob; Ha, Myungjin; Yu, Sungkon; Jang, Seulki; Jung, Byungjo

2016-03-01

A stereoscopic imaging modality was developed for the application of ophthalmology surgical microscopes. A previous study has already introduced a single-channel stereoscopic video imaging modality based on a transparent rotating deflector (SSVIM-TRD), in which two different view angles, image disparity, are generated by imaging through a transparent rotating deflector (TRD) mounted on a stepping motor and is placed in a lens system. In this case, the image disparity is a function of the refractive index and the rotation angle of TRD. Real-time single-channel stereoscopic ophthalmology microscope (SSOM) based on the TRD is improved by real-time controlling and programming, imaging speed, and illumination method. Image quality assessments were performed to investigate images quality and stability during the TRD operation. Results presented little significant difference in image quality in terms of stability of structural similarity (SSIM). A subjective analysis was performed with 15 blinded observers to evaluate the depth perception improvement and presented significant improvement in the depth perception capability. Along with all evaluation results, preliminary results of rabbit eye imaging presented that the SSOM could be utilized as an ophthalmic operating microscopes to overcome some of the limitations of conventional ones.

The objective lens of the electron microscope with correction of spherical and axial chromatic aberrations.

PubMed

Bimurzaev, S B; Aldiyarov, N U; Yakushev, E M

2017-10-01

The paper describes the principle of operation of a relatively simple aberration corrector for the transmission electron microscope objective lens. The electron-optical system of the aberration corrector consists of the two main elements: an electrostatic mirror with rotational symmetry and a magnetic deflector formed by the round-shaped magnetic poles. The corrector operation is demonstrated by calculations on the example of correction of basic aberrations of the well-known objective lens with a bell-shaped distribution of the axial magnetic field. Two of the simplest versions of the corrector are considered: a corrector with a two-electrode electrostatic mirror and a corrector with a three-electrode electrostatic mirror. It is shown that using the two-electrode mirror one can eliminate either spherical or chromatic aberration of the objective lens, without changing the value of its linear magnification. Using a three-electrode mirror, it is possible to eliminate spherical and chromatic aberrations of the objective lens simultaneously, which is especially important in designing electron microscopes with extremely high resolution. © The Author 2017. Published by Oxford University Press on behalf of The Japanese Society of Microscopy. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Bolt-on source of spin-polarized electrons for inverse photoemission

NASA Astrophysics Data System (ADS)

Schedin, Fredrik; Warburton, Ranald; Thornton, Geoff

1998-06-01

We have developed a portable spin-polarized electron gun which can be bolted on to an ultrahigh vacuum chamber. The gun has been successfully operated with an electron gun to target distance of about 150 mm. This allows accommodation of other surface science equipment in the same vacuum system. The spin-polarized electrons are obtained via photoemission from a negative electron affinity GaAs(001) surface with circularly polarized light. A transversely polarized beam is achieved with a 90° electrostatic deflector. A set of two three-element electrostatic tube lenses are employed to transport and to focus the electrons onto a target. The measured transmission through the electron optics is >70% for electron energies in the range 7-20 eV. This is achieved by using large diameter electron transport lenses. The energy resolution of the electron beam is measured to be better than 0.27 eV and the polarization is determined to be 25±5%.

Unsteady loading of a vertical-axis turbine in the interaction with an upstream deflector

NASA Astrophysics Data System (ADS)

Kim, Daegyoum; Gharib, Morteza

2014-01-01

Torque generation and flow distribution of a lift-based vertical-axis turbine with an upstream deflecting plate are investigated in water tunnel experiments. The deployment of a deflector in front of a lift-based turbine is a promising approach to increase local flow velocity and enhance energy conversion efficiency without consideration for complicated control. For the turbine with the deflector, the phase during which the blade passes near the front end of the turbine has a major contribution to torque increase from the case without the deflector. Meanwhile, the deflector can have a negative effect in torque generation at the phase when the blade moves upstream against free stream if the turbine is placed close to the deflector in a crosswise direction. The change of nearby flow distribution by the deflector is also examined to find its correlation with torque generation. When the blade rotates through the near-wake region of the deflector, the blade can collides with the vortical structure shed from the deflector. This interaction causes significant torque fluctuation.

Effect of confining wall potential on charged collimated dust beam in low-pressure plasma

NASA Astrophysics Data System (ADS)

Kausik, S. S.; Kakati, B.; Saikia, B. K.

2013-05-01

The effect of confining wall potential on charged collimated dust beam in low-pressure plasma has been studied in a dusty plasma experimental setup by applying electrostatic field to each channel of a multicusp magnetic cage. Argon plasma is produced by hot cathode discharge method at a pressure of 5×10-4 millibars and is confined by a full line cusped magnetic field confinement system. Silver dust grains are produced by gas-evaporation technique and move upward in the form of a collimated dust beam due to differential pressure maintained between the dust and plasma chambers. The charged grains in the beam after coming out from the plasma column enter into the diagnostic chamber and are deflected by a dc field applied across a pair of deflector plates at different confining potentials. Both from the amount of deflection and the floating potential, the number of charges collected by the dust grains is calculated. Furthermore, the collimated dust beam strikes the Faraday cup, which is placed above the deflector plates, and the current (˜pA) so produced is measured by an electrometer at different confining potentials. The experimental results demonstrate the significant effect of confining wall potential on charging of dust grains.

Noise of deflectors used for flow attachment with STOL-OTW configurations

NASA Technical Reports Server (NTRS)

Vonglahn, U. H.; Groesbeck, D.

1977-01-01

Future STOL aircraft may utilize engine-over-the-wing installations in which the exhaust nozzles are located above and separated from the upper surface of the wing. An external jet flow deflector can be used with such installations to provide flow attachment to the wing/flap surfaces for lift augmentation. Deflector noise in the flyover plane measured with several model-scale nozzle/deflector/wing configurations is examined. The deflector-associated noise is correlated in terms of velocity and geometry parameters. The data also indicate that the effective overall sound pressure level of the deflector-associated noise peaks in the forward quadrant near 40 deg from the inlet axis.

A Guide for Estimation of Aeroacoustic Loads on Flight Vehicle Surfaces

DTIC Science & Technology

1977-02-01

Nozzle aspect ratio correction of one-third octave band sound pressure levels of USB noise . 122 31. Impingement angle correction of one-third octave...breech weapons ....................... 175 IX •: •-•,..i .•,z. •... LIST OF FIGURES (Cont.) page Figure 61. Rectangular cavity ...and a nozzle aspect ratio of 4.0, and without a deflector. Obtain the corrected one-third octave band level SPL from the baseline level, from " b

Assessment at full scale of exhaust nozzle-to-wing size on STOL-OTW acoustic characteristics

NASA Technical Reports Server (NTRS)

Von Glahn, U.; Groesbeck, D.

1979-01-01

On the basis of static zero/acoustic data obtained at model scale, the effect of exhaust nozzle size on flyover noise is evaluated at full scale for different STOL-OTW nozzle configurations. Three types of nozzles are evaluated: a circular/deflector nozzle mounted above the wing, a slot/deflector nozzle mounted on the wing, and a slot nozzle mounted on the wing. The nozzle exhaust plane location, measured from the wing leading edge was varied from 10 to 46 percent of the wing chord (flaps retracted). Flap angles of 20 deg (takeoff) and 60 deg (approach) are included in the study. Initially, perceived noise levels (PNL) are calculated as a function of flyover distance at 152 m altitude. From these plots static EPNL values, defined as flyover relative noise levels, then are obtained as functions of nozzle size for equal aerodynamic performance (lift and thrust). On the basis of these calculations, the acoustic benefits attributable to nozzle size relative to a given wing chord size are assessed.

Assessment at full scale of exhaust nozzle to wing size on STOL-OTW acoustic characteristics

NASA Technical Reports Server (NTRS)

Vonglahn, U.; Grosbeck, D.

1979-01-01

On the basis of static aero/acoustic data obtained at model scale, the effect of exhaust nozzle size on flyover noise is evaluated at full scale for different STOL-OTW nozzle configurations. Three types of nozzles are evaluated: a circular/deflector nozzle mounted above the wing; a slot/deflector nozzle mounted on the wing; and a slot nozzle mounted on the wing. The nozzle exhaust plane location, measured from the wing leading edge, was varied from 10 to 46 percent of the wing chord (flaps retracted). Flap angles of 20 deg (takeoff) and 60 deg (approach) are included in the study. Initially, perceived noise levels (PNL) are calculated as a function flyover distance at 152m altitude. From these plots, static EPNL values (defined as flyover relative noise levels), are obtained as functions of nozzle size for equal aerodynamic performance (lift and thrust). The acoustic benefits attributable to nozzle size relative to a given wing chord size are assessed.

Role of electrostatic interactions in the assembly of empty spherical viral capsids

NASA Astrophysics Data System (ADS)

Šiber, Antonio; Podgornik, Rudolf

2007-12-01

We examine the role of electrostatic interactions in the assembly of empty spherical viral capsids. The charges on the protein subunits that make the viral capsid mutually interact and are expected to yield electrostatic repulsion acting against the assembly of capsids. Thus, attractive protein-protein interactions of nonelectrostatic origin must act to enable the capsid formation. We investigate whether the interplay of repulsive electrostatic and attractive interactions between the protein subunits can result in the formation of spherical viral capsids of a preferred radius. For this to be the case, we find that the attractive interactions must depend on the angle between the neighboring protein subunits (i.e., on the mean curvature of the viral capsid) so that a particular angle(s) is (are) preferred energywise. Our results for the electrostatic contributions to energetics of viral capsids nicely correlate with recent experimental determinations of the energetics of protein-protein contacts in the hepatitis B virus [P. Ceres A. Zlotnick, Biochemistry 41, 11525 (2002)].

High Efficiency Large-Angle Pancharatnam Phase Deflector Based on Dual Twist Design

DTIC Science & Technology

2016-12-16

previous approaches have been reported, with an even wider range of potential applications8-13. Figure 1a shows the schematics of a thin- film beam...using a liquid crystal device. SID Symp. Dig. Tech. Papers 45, 739–742 (2014). 10. Gao, K., Cheng, H. H., Bhowmik, A. K. & Bos, P. J. Thin- film ...efficient thin- film polarizing beamsplitters for broadband light. Proc. SPIE 6682, 668211 (2007). Acknowledgements We express thanks for financial

[Aerodynamic characteristics of crewman's arms during windblast].

PubMed

Zhang, Yun-ran; Wu, Gui-rong

2003-10-01

To study the aerodynamic characteristics of crewman's arms with or without protective devices in the status with raised legs or not. The experiments were performed in an FL-24 transonic and supersonic wind tunnel, over Mach number range of 0.4-2.0, with 5 degrees-30 degrees angles of attack, 0 degrees - 90 degrees sideslip angles and Re number of (0.93-3.1) x 10(6). The test model was a 1/5-scale crewman/ejection seat combination. The aerodynamic characteristics of the various sections of crewman's arms were studied and analyzed. The results showed that 1) The effect of raised leg on the aerodynamic characteristics of the crewman's arms was very evident, and was related to the status of leg raising; 2) The sideslip considerably increased aerodynamic loads on the crewman's arms, in particular when beta=50 degrees the loads was severe in the test; 3) The tested protective devices was valid, the effectiveness of wind deflector in protecting crewman's arms was evident; 4) A formula for calculating aerodynamic force acting on crewman's arms was presented. 1)The tested protective devices was valid, and the effectiveness of wind deflector in protecting crewman's arms was evident; 2) An aerodynamic basis for the development of crewman windblast protective device was presented; 3)The calculation formula presented is useful in estimating aerodynamic forces of crewman's arms.

Overview of the future upgrade of the INFN-LNS superconducting cyclotron

NASA Astrophysics Data System (ADS)

Calabretta, Luciano; Calanna, Alessandra; Cuttone, Giacomo; D'Agostino, Grazia; Rifuggiato, Danilo; Domenico Russo, Antonio

2017-06-01

The LNS Superconducting Cyclotron, named “Ciclotrone Superconduttore” (CS), has been in operation for more than 20 years. A wide range of ion species from hydrogen to lead, with energy in the range 10 to 80 AMeV, have been delivered to users. The maximum beam power is limited to 100 W due to the beam dissipation on the electrostatic deflectors. To fulfil the demand of users aiming at studying rare processes in nuclear physics, an upgrade of the cyclotron is necessarily intended to increase the intensity of ion beams with mass lower than 40 a.m.u. up to a power 10 kW. This will be achieved by means of extraction by stripping. This solution needs to replace the cryostat including the superconducting coils. The present capability of the cyclotron will be maintained, i.e. all the ion species allowed by the operating diagram will be available, being extracted by electrostatic extraction. In addition to the high power beams for nuclear physics, it will be possible to produce medical radioisotopes like 211At using an internal target.

Study of a condition for the mode conversion from purely perpendicular electrostatic waves to electromagnetic waves

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

Kalaee, Mohammad Javad, E-mail: mjkalaee@ut.ac.ir; Katoh, Yuto, E-mail: yuto@stpp.gp.tohoku.ac.jp

One of the mechanisms for generating electromagnetic plasma waves (Z-mode and LO-mode) is mode conversion from electrostatic waves into electromagnetic waves in inhomogeneous plasma. Herein, we study a condition required for mode conversion of electrostatic waves propagating purely perpendicular to the ambient magnetic field, by numerically solving the full dispersion relation. An approximate model is derived describing the coupling between electrostatic waves (hot plasma Bernstein mode) and Z-mode waves at the upper hybrid frequency. The model is used to study conditions required for mode conversion from electrostatic waves (electrostatic electron cyclotron harmonic waves, including Bernstein mode) into electromagnetic plasma wavesmore » (LO-mode). It is shown that for mode conversion to occur in inhomogeneous plasma, the angle between the boundary surface and the magnetic field vector should be within a specific range. The range of the angle depends on the norm of the k vector of waves at the site of mode conversion in the inhomogeneous region. The present study reveals that inhomogeneity alone is not a sufficient condition for mode conversion from electrostatic waves to electromagnetic plasma waves and that the angle between the magnetic field and the density gradient plays an important role in the conversion process.« less

On the equilibrium charge density at tilt grain boundaries

NASA Astrophysics Data System (ADS)

Srikant, V.; Clarke, D. R.

1998-05-01

The equilibrium charge density and free energy of tilt grain boundaries as a function of their misorientation is computed using a Monte Carlo simulation that takes into account both the electrostatic and configurational energies associated with charges at the grain boundary. The computed equilibrium charge density increases with the grain-boundary angle and approaches a saturation value. The equilibrium charge density at large-angle grain boundaries compares well with experimental values for large-angle tilt boundaries in GaAs. The computed grain-boundary electrostatic energy is in agreement with the analytical solution to a one-dimensional Poisson equation at high donor densities but indicates that the analytical solution overestimates the electrostatic energy at lower donor densities.

Stress induced modulation of magnetic domain diffraction of single crystalline yttrium iron garnet

NASA Astrophysics Data System (ADS)

Mito, Shinichiro; Yoshihara, Yuki; Takagi, Hiroyuki; Inoue, Mitsuteru

2018-05-01

Stress induced modulation of the diffraction angle and efficiency of the light reflected from a stripe-domain magnetic garnet was demonstrated. The spacing of the magnetic domain was changed using the inverse magnetostriction effect. The sample structure was a piezo actuator/Al reflection layer/magnetic garnet substrate. A diffraction angle between the 0th and 1st ordered light was changed from 9.12 deg. to 10.20 deg. This result indicates that the domain spacing was changed from 3.3 μm to 3.0 μm. The change of the diffraction angle was irreversible for the voltage. However, reversible, linear and continuous change of the diffraction efficiency was observed. These results could be applicable for a voltage-driven optical solid state light deflector with low power consumption and high switching speed.

Photovoltaic module with removable wind deflector

DOEpatents

Botkin, Jonathan [El Cerrito, CA; Graves, Simon [Berkeley, CA; Danning, Matt [Oakland, CA; Culligan, Matthew [Berkeley, CA

2012-08-07

A photovoltaic (PV) module assembly including a PV module, a deflector, and a clip. The PV module includes a PV device and a frame. A PV laminate is assembled to the frame, and the frame includes a support arm forming a seat. The deflector defines a front face and a rear face, with the clip extending from either the trailing frame member or the rear face of the deflector. In a mounted state, the deflector is nested within the seat and is releasably mounted to the trailing frame member via the clip. In some embodiments, the support arm forms a second seat, with the PV module assembly providing a second mounted state in which the deflector is in a differing orientation/slope, nested within the second seat and releasably mounted to the trailing frame member via the clip.

Photovoltaic module with removable wind deflector

DOEpatents

Botkin, Jonathan; Graves, Simon; Danning, Matt; Culligan, Matthew

2014-02-18

A photovoltaic (PV) module assembly including a PV module, a deflector, and a clip. The PV module includes a PV device and a frame. A PV laminate is assembled to the frame, and the frame includes a support arm forming a seat. The deflector defines a front face and a rear face, with the clip extending from either the trailing frame member or the rear face of the deflector. In a mounted state, the deflector is nested within the seat and is releasably mounted to the trailing frame member via the clip. In some embodiments, the support arm forms a second seat, with the PV module assembly providing a second mounted state in which the deflector is in a differing orientation/slope, nested within the second seat and releasably mounted to the trailing frame member via the clip.

Photovoltaic module with removable wind deflector

DOEpatents

Botkin, Jonathan; Graves, Simon; Danning, Matt; Culligan, Matthew

2013-05-28

A photovoltaic (PV) module assembly including a PV module, a deflector, and a clip. The PV module includes a PV device and a frame. A PV laminate is assembled to the frame, and the frame includes a support arm forming a seat. The deflector defines a front face and a rear face, with the clip extending from either the trailing frame member or the rear face of the deflector. In a mounted state, the deflector is nested within the seat and is releasably mounted to the trailing frame member via the clip. In some embodiments, the support arm forms a second seat, with the PV module assembly providing a second mounted state in which the deflector is in a differing orientation/slope, nested within the second seat and releasably mounted to the trailing frame member via the clip.

Flame Deflector Section, Elevation, Water Supply Flow Diagram, Exploded ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Flame Deflector - Section, Elevation, Water Supply Flow Diagram, Exploded Deflector Manifolds, and Interior Perspective - Marshall Space Flight Center, F-1 Engine Static Test Stand, On Route 565 between Huntsville and Decatur, Huntsville, Madison County, AL

Design of Deflectors for Little Goose Spillway, Snake River, Oregon: A Physical Model Study

DTIC Science & Technology

2017-06-01

model of the spillway. Four different deflector designs were compared relative to flow conditions in the stilling basin and tailrace area of the...performance in a 1:40-scale section model of the spillway. Four different deflector designs were compared relative to flow conditions in the stilling basin and...ER D C/ CH L TR -1 7- 10 Dissolved Gas Abatement Studies Design of Deflectors for Little Goose Spillway, Snake River, Oregon A

Surface pressure fluctuations due to an impinging underexpanded supersonic jet

NASA Astrophysics Data System (ADS)

Pundir, Binu

The impingement of supersonic jets on surfaces is of interest because of its important application to jet blast deflectors (JBD), and short takeoff and vertical landing aircraft (STOVL) during hover. Typically, on an aircraft carrier deck, the impingement of the jet blast on the deflector generates impingement tones, and structural vibrations, not only on the JBD but also on the ship deck. Therefore, apart from direct transmission of jet noise to the gallery level, there is a component of noise transmitted due to the impingement of the jet on the JBD. The objectives of this work are to study the pressure spectra (i) on a flat plate, and separately on a cone due to axisymmetric impingement of a supersonic underexpanded cold jet issuing from a convergent-divergent nozzle and (ii) on a plane jet impinging on a finite plate and an adjoining ground plane due to the impingement of a planar jet on the plate. The characteristics of the surface pressure fluctuations are numerically investigated using WIND-US 2.0. The time-dependent, compressible Euler equations for perfect gas are employed for the present computations. The impingement distance between the jet nozzle and the deflector plate, and the plate inclination with respect to the incident jet are varied. The impingement zone stagnation bubble and a high-speed radial jet with several embedded structures (shocklets) were identified on the perpendicular plate. Flows involving cones reveal the presence of detached cone shocks, enclosing a recirculation zone. The location and magnitude of the peak pressure on the cone surface are a strong function of the cone apex angle. For the two-dimensional jet impingement on angled plate the peak value of pressure occurs at normal jet impingement. The pressure at the intersection point of the plate and the ground plane is sometimes higher than the peak pressure on the plate. Beyond this point there is a sharp decrease in pressure. As the flow accelerates, an oblique shock is sometimes formed in this grazing flow region. A recirculation region at the lower lip of the nozzle was observed for all the separation distances and plate inclinations.

Electro-optic and acousto-optic scanning and deflection

NASA Astrophysics Data System (ADS)

Gottlieb, M.; Ireland, C. L. M.; Ley, J. M.

This book attempts to cover sufficient electro- and acousto-optic theory for the reader to understand and appreciate the design and application of solid state optical deflectors. It is also hoped that for the more experienced engineer the book will serve as a useful reference book covering the most important work in this field of engineering. The theory of the electro-optic effect is considered along with the properties and selection of electro-optic materials, the principles of electro-optic deflectors, electro-optic deflector designs, and applications for electro-optic deflectors. Attention is given to EM wave propagation in a crystal, the linear electro-optic effect, the quadratic electro-optic effect in crystals and in liquids, electro-optic ceramics in the (Pb,La)(Zr,Ti)O3 system, and digital and analog light deflectors. Aspects related to acousto-optic deflectors are discussed, taking into account acousto-optic interactions, materials for acousto-optic scanning, acoustic techniques, scanning systems, and acousto-optic light diffraction in thin films.

Active liquid-crystal deflector and lens with Fresnel structure

NASA Astrophysics Data System (ADS)

Shibuya, Giichi; Yamano, Shohei; Yoshida, Hiroyuki; Ozaki, Masanori

2017-02-01

A new type of tunable Fresnel deflector and lens composed of liquid crystal was developed. Combined structure of multiple interdigitated electrodes and the high-resistivity (HR) layer implements the saw-tooth distribution of electrical potential with only the planar surfaces of the transparent substrates. According to the numerical calculation and design, experimental devices were manufactured with the liquid crystal (LC) material sealed into the sandwiched flat glass plates of 0.7 mm thickness with rubbed alignment layers set to an anti-parallel configuration. Fabricated beam deflector with no moving parts shows the maximum tilt angle of +/-1.3 deg which can apply for optical image stabilizer (OIS) of micro camera. We also discussed and verified their lens characteristics to be extended more advanced applications. Transparent interdigitated electrodes were concentrically aligned on the lens aperture with the insulator gaps under their boundary area. The diameter of the lens aperture was 30 mm and the total number of Fresnel zone was 100. Phase retardation of the beam wavefront irradiated from the LC lens device can be evaluated by polarizing microscope images with a monochromatic filter. Radial positions of each observed fringe are plotted and fitted with 2nd degree polynomial approximation. The number of appeared fringes is over 600 in whole lens aperture area and the correlation coefficients of all approximations are over 0.993 that seems enough ideal optical wavefront. The obtained maximum lens powers from the approximations are about +/-4 m-1 which was satisfied both convex and concave lens characteristics; and their practical use for the tunable lens grade eyeglasses became more prospective.

Accurate on line measurements of low fluences of charged particles

NASA Astrophysics Data System (ADS)

Palla, L.; Czelusniak, C.; Taccetti, F.; Carraresi, L.; Castelli, L.; Fedi, M. E.; Giuntini, L.; Maurenzig, P. R.; Sottili, L.; Taccetti, N.

2015-03-01

Ion beams supplied by the 3MV Tandem accelerator of LABEC laboratory (INFN-Firenze), have been used to study the feasibility of irradiating materials with ion fluences reproducible to about 1%. Test measurements have been made with 7.5 MeV 7Li2+ beams of different intensities. The fluence control is based on counting ions contained in short bursts generated by chopping the continuous beam with an electrostatic deflector followed by a couple of adjustable slits. Ions are counted by means of a micro-channel plate (MCP) detecting the electrons emitted from a thin layer of Al inserted along the beam path in between the pulse defining slits and the target. Calibration of the MCP electron detector is obtained by comparison with the response of a Si detector.

Development of a low energy electron spectrometer for SCOPE

NASA Astrophysics Data System (ADS)

Tominaga, Yuu; Saito, Yoshifumi; Yokota, Shoichiro

We are newly developing a low-energy charged particle analyzer for the future satellite mission SCOPE (cross Scale COupling in the Plasma universE). The main purpose of the mission is to understand the cross scale coupling between macroscopic MHD scale phenomena and microscopic ion and electron-scale phenomena. In order to under-stand the dynamics of plasma in small scales, we need to observe the plasma with an analyzer which has high time resolution. For ion-scale phenomena, the time resolution must be as high as ion cyclotron frequency (-10 sec) in Earth's magnetosphere. However, for electron-scale phe-nomena, the time resolution must be as high as electron cyclotron frequency (-1 msec). The GEOTAIL satellite that observes Earth's magnetosphere has the analyzer whose time resolution is 12 sec, so the satellite can observe ion-scale phenomena. However in the SCOPE mission, we will go further to observe electron-scale phenomena. Then we need analyzers that have at least several msec time resolution. Besides, we need to make the analyzer as small as possible for the volume and weight restrictions of the satellite. The diameter of the top-hat analyzer must be smaller than 20 cm. In this study, we are developing an electrostatic analyzer that meets such requirements using numerical simulations. The electrostatic analyzer is a spherical/toroidal top-hat electrostatic analyzer with three nested spherical/toroidal deflectors. Using these deflectors, the analyzer measures charged particles simultaneously in two different energy ranges. Therefore time res-olution of the analyzer can be doubled. With the analyzer, we will measure energies from 10 eV to 22.5 keV. In order to obtain three-dimensional distribution functions of low energy parti-cles, the analyzer must have 4-pi str field of view. Conventional electrostatic analyzers use the spacecraft spin to have 4-pi field of view. So the time resolution of the analyzer depends on the spin frequency of the spacecraft. However, we cannot secure the several msec time resolution by using the spacecraft spin. In the SCOPE mission, we set 8 pairs of two nested electrostatic analyzers on each side of the spacecraft, which enable us to secure 4-pi field of view altogether. Then the time resolution of the analyzer does not depend on the spacecraft spin. Given that the sampling time of the analyzer is 0.5 msec, the time resolution of the analyzer can be 8 msec. In order to secure the time resolution as high as 10 msec, the geometric factor of the analyzer has to be as high as 8*10-3 (cm2 str eV/eV/22.5deg). Higher geometric factor requires bigger instrument. However, we have to reduce the volume and weight of the instrument to set it on the satellite. Under these restrictions, we have realized the analyzer which has the geometric factors of 7.5*10-3 (cm2 str eV/eV/22.5deg) (inner sphere) and 10.0*10-3 (cm2 str eV/eV/22.5deg) (outer sphere) with diameter of 17.4 cm.

DNA minor groove electrostatic potential: influence of sequence-specific transitions of the torsion angle gamma and deoxyribose conformations.

PubMed

Zhitnikova, M Y; Shestopalova, A V

2017-11-01

The structural adjustments of the sugar-phosphate DNA backbone (switching of the γ angle (O5'-C5'-C4'-C3') from canonical to alternative conformations and/or C2'-endo → C3'-endo transition of deoxyribose) lead to the sequence-specific changes in accessible surface area of both polar and non-polar atoms of the grooves and the polar/hydrophobic profile of the latter ones. The distribution of the minor groove electrostatic potential is likely to be changing as a result of such conformational rearrangements in sugar-phosphate DNA backbone. Our analysis of the crystal structures of the short free DNA fragments and calculation of their electrostatic potentials allowed us to determine: (1) the number of classical and alternative γ angle conformations in the free B-DNA; (2) changes in the minor groove electrostatic potential, depending on the conformation of the sugar-phosphate DNA backbone; (3) the effect of the DNA sequence on the minor groove electrostatic potential. We have demonstrated that the structural adjustments of the DNA double helix (the conformations of the sugar-phosphate backbone and the minor groove dimensions) induce changes in the distribution of the minor groove electrostatic potential and are sequence-specific. Therefore, these features of the minor groove sizes and distribution of minor groove electrostatic potential can be used as a signal for recognition of the target DNA sequence by protein in the implementation of the indirect readout mechanism.

Optical/Infrared Properties of Atmospheric Aerosols with an In-Situ, Multi-Wavelength, Multichannel Nephelometer System.

DTIC Science & Technology

1985-04-01

from any angle of approach. An angular impetus is imparted to the particle 25 7. motion via the eight evenly spaced entrance vanes. As the particles...measurement cycle. 2 f.. 27 VA NE S M= VANE ASSEMBLY BASE IN SECT SCREEN TUBE PROTECTIVE CPLUGHOUSING HOUSING-DEFLECTORAEOYMIINT SPACING PHAEO YNAI N...AERODYNAMIC FLOW DEFLECTOR OUTER TUJBE TAPERED p. Figure 3 r Wedding PM 1 0 Inlet [I]J 28 . .I .. II | I I J . 1 _1 ! I 7 I ! . ?. . . - 120 -- WEDDING INLET

Simplified mathematical model of losses in a centrifugal compressor stage

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

Seleznev, K.P.; Galerkin, Yu.B.; Popova, E.Yu.

1988-05-01

A mathematical model was developed for optimizing the parameters of the stage which does not require calculation of the flow around grids. The loss coefficients of the stage elements were considered as functions of the flow-through section, the angle of incidence, the compressibility criterion, and the Reynolds number. The relationships were used to calculate losses in all blade components, including blade diffusers, deflectors, and rotors. The model is implemented in a microcomputer and will compute the efficiency of one variant of the flow-through section of a stage in 60 minutes.

Nuclear reactor downcomer flow deflector

DOEpatents

Gilmore, Charles B [Greensburg, PA; Altman, David A [Pittsburgh, PA; Singleton, Norman R [Murrysville, PA

2011-02-15

A nuclear reactor having a coolant flow deflector secured to a reactor core barrel in line with a coolant inlet nozzle. The flow deflector redirects incoming coolant down an annulus between the core barrel and the reactor vessel. The deflector has a main body with a front side facing the fluid inlet nozzle and a rear side facing the core barrel. The rear side of the main body has at least one protrusion secured to the core barrel so that a gap exists between the rear side of the main body adjacent the protrusion and the core barrel. Preferably, the protrusion is a relief that circumscribes the rear side of the main body.

Investigation at Low Speeds of Deflectors and Spoilers as Gust Alleviators on a Model of the Bell X-5 Airplane with 35 Degree Swept Wings and on a High-aspect-ratio 35 Degree Swept-wing-fuselage Model

NASA Technical Reports Server (NTRS)

Croom, Delwin R; Huffman, Jarrett K

1957-01-01

Results of an investigation at low speeds to determine the gust-alleviation capabilities (reduction in lift-curve slope) of spoilers and deflectors on a 35 degree swept-wing model of high aspect ratio and on a 1/4-scale model of the X-5 airplane with 35 degree swept wings indicate that deflector and spoiler-deflector types of controls can be designed to provide considerable gust alleviation for a swept-wing airplane while still maintaining stability and control.

Numerical study for flame deflector design of a space launch vehicle

NASA Astrophysics Data System (ADS)

Oh, Hwayoung; Lee, Jungil; Um, Hyungsik; Huh, Hwanil

2017-04-01

A flame deflector is a structure that prevents damage to a launch vehicle and a launch pad due to exhaust plumes of a lifting-off launch vehicle. The shape of a flame deflector should be designed to restrain the discharged gas from backdraft inside the deflector and to reflect the impact to the surrounding environment and the engine characteristics of the vehicle. This study presents the five preliminary flame deflector configurations which are designed for the first-stage rocket engine of the Korea Space Launch Vehicle-II and surroundings of the Naro space center. The gas discharge patterns of the designed flame deflectors are investigated using the 3D flow field analysis by assuming that the air, in place of the exhaust gas, forms the plume. In addition, a multi-species unreacted flow model is investigated through 2D analysis of the first-stage engine of the KSLV-II. The results indicate that the closest Mach number and temperature distributions to the reacted flow model can be achieved from the 4-species unreacted flow model which employs H2O, CO2, and CO and specific heat-corrected plume.

Electrostatic Interactions Between Glycosaminoglycan Molecules

NASA Astrophysics Data System (ADS)

Song, Fan; Moyne, Christian; Bai, Yi-Long

2005-02-01

The electrostatic interactions between nearest-neighbouring chondroitin sulfate glycosaminoglycan (CS-GAG) molecular chains are obtained on the bottle brush conformation of proteoglycan aggrecan based on an asymptotic solution of the Poisson-Boltzmann equation the CS-GAGs satisfy under the physiological conditions of articular cartilage. The present results show that the interactions are associated intimately with the minimum separation distance and mutual angle between the molecular chains themselves. Further analysis indicates that the electrostatic interactions are not only expressed to be purely exponential in separation distance and decrease with the increasing mutual angle but also dependent sensitively on the saline concentration in the electrolyte solution within the tissue, which is in agreement with the existed relevant conclusions.

Optical Distance Measurement Device And Method Thereof

DOEpatents

Bowers, Mark W.

2004-06-15

A system and method of efficiently obtaining distance measurements of a target by scanning the target. An optical beam is provided by a light source and modulated by a frequency source. The modulated optical beam is transmitted to an acousto-optical deflector capable of changing the angle of the optical beam in a predetermined manner to produce an output for scanning the target. In operation, reflected or diffused light from the target may be received by a detector and transmitted to a controller configured to calculate the distance to the target as well as the measurement uncertainty in calculating the distance to the target.

Very High Reflectivity Supermirrors And Their Applications

NASA Astrophysics Data System (ADS)

Mezei, F.

1989-01-01

Very high reflectivity (some 95 % or better) supermirrors, with cut-off angles up to 2 times the critical angle of Ni coated simple total reflection neutron mirrors, can be produced using well established conventional deposition techniques. This performance makes applications involving multiple reflections and transmission geometries feasible, which in turn allow us to use more sophisticated neutron optical systems in order to optimize performance and minimize the amount a scarce supermirrors required. A key feature of several of these novel systems is the distribution of tasks between the several optical components achieving the desired performance by multiple action. The design and characteristics of a series of novel applications, such as polarizing cavities, collimators and guides, non-polarizing guides, beam compressors, deflectors and splitters (most of them tested or being implemented) are the main subjects of the present paper.

Artificial neural network modeling of a deflector in a grooved channel as well as optimization of its effective parameters

NASA Astrophysics Data System (ADS)

Abdollahi, Azita; Shams, Mehrzad; Abdollahi, Anita

2018-01-01

One of methods available to increase the rate of heat transfer in channels with parallel plates is making grooves in them. But, the fundamental problem of this method is the formation of stagnation zone in the grooves and as a result formation a zone with low energy transfer. In this paper, the effect of placing curved deflectors (geometries with elliptical forms) in channel on thermal and hydraulic characteristic of the fluid flow- with the aim of directing of the flow into the grooves and as a result increasing the rate of heat transfer in this zone- are investigated and heat transfer coefficient and pressure drop are calculated for different values of Reynolds number and geometrical parameters of the deflector (its small and large radiuses). The results show that the presence of the deflector in the channel significantly increases the heat transfer rate compare to the channel without deflector. Of course, it should be noted that this work also increases the pressure drop. So, finally in order to determine configurations of the deflector causing minimum pressure drop, maximum Nusselt number or a balance between them, optimization algorithm consisting of artificial neural network and multi-objective genetic algorithm was utilized to calculate the optimal values of these parameters.

KSC-08pd1584

NASA Image and Video Library

2008-06-02

CAPE CANAVERAL, Fla. -- A member of the walk-down team takes a close look at debris scattered across Launch Pad 39A at NASA's Kennedy Space Center following launch of space shuttle Discovery on its STS-124 mission. During the post-launch walk down, the pad team noted severe launch damage on a 100’ X 20’ section of the east wall of the north flame trench. Broken sections of the flame trench wall were scattered from the flame trench to the pad perimeter fence. NASA is forming an investigation board. The flame trench transecting the pad's mound at ground level is 490 feet long, 58 feet wide and 40 feet high. It is made of concrete and refractory brick. The top of the solid rocket booster flame deflector abuts with that of the orbiter flame deflector to form a flattened, inverted V-shaped structure beneath the mobile launcher platform's three exhaust holes. The orbiter flame deflector is fixed and is 38 feet high, 72 feet long and 57.6 feet wide. The deflector weighs 1.3 million pounds. The solid rocket booster deflector is 42.5 feet high, 42 feet long and 57 feet wide. The structure weighs 1.1 million pounds. The deflectors are built of steel and covered with a high-temperature concrete surface with an average thickness of 5 inches. There are two movable solid rocket booster side flame deflectors, one located on each side of the flame trench. They are 19.5 feet high, 44 feet long and 17.5 feet wide. Photo credit: NASA/Jim Grossmann

Narrow infrasound pulses from lightning; are they of electrostatic or thermal origin?

NASA Astrophysics Data System (ADS)

CHUM, Jaroslav; Diendorfer, Gerhard; Šindelářová, Tereza; Baše, Jiří; Hruška, František

2014-05-01

Narrow (~1-2 s) infrasound pulses that followed, with ~11 to ~50 s delays, rapid changes of electrostatic field were observed by a microbarometer array in the Czech Republic during thunderstorm activity. The angles of arrival (azimuth and elevation) were analyzed for selected distinct events. Comparisons of distances and azimuths of infrasound sources from the center of microbarometer array with lightning locations determined by EUCLID lightning detection network show that most of the selected events are most likely associated with intra-cloud (IC) discharges. Preceding rapid changes of electrostatic field, potential association of infrasound pulses with IC discharges, and high elevation angles of arrival for near infrasound sources indicate that an electrostatic mechanism is probably responsible for their generation. It is discussed that distinguishing of the relative role of thermal and electrostatic mechanism is difficult, and that none of published models of electrostatic production of infrasound thunder can explain the presented observations precisely. A modification of the current models, based on consideration of at least two charged layers is suggested. Further theoretical and experimental investigations are however needed to get a better description of the generation mechanism of those infrasound pulses.

Design and optimization of a modular setup for measurements of three-dimensional spin polarization with ultrafast pulsed sources.

PubMed

Pincelli, T; Petrov, V N; Brajnik, G; Ciprian, R; Lollobrigida, V; Torelli, P; Krizmancic, D; Salvador, F; De Luisa, A; Sergo, R; Gubertini, A; Cautero, G; Carrato, S; Rossi, G; Panaccione, G

2016-03-01

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric and magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps).

Design and optimization of a modular setup for measurements of three-dimensional spin polarization with ultrafast pulsed sources

NASA Astrophysics Data System (ADS)

Pincelli, T.; Petrov, V. N.; Brajnik, G.; Ciprian, R.; Lollobrigida, V.; Torelli, P.; Krizmancic, D.; Salvador, F.; De Luisa, A.; Sergo, R.; Gubertini, A.; Cautero, G.; Carrato, S.; Rossi, G.; Panaccione, G.

2016-03-01

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric and magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps).

Design and optimization of a modular setup for measurements of three-dimensional spin polarization with ultrafast pulsed sources

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

Pincelli, T., E-mail: pincelli@iom.cnr.it; Rossi, G.; Laboratorio TASC, IOM-CNR, S.S. 14 km 163.5, Basovizza, 34149 Trieste

2016-03-15

ULTRASPIN is an apparatus devoted to the measurement of the spin polarization (SP) of electrons ejected from solid surfaces in a UHV environment. It is designed to exploit ultrafast light sources (free electron laser or laser high harmonic generation) and to perform (photo)electron spin analysis by an arrangement of Mott scattering polarimeters that measure the full SP vector. The system consists of two interconnected UHV vessels: one for surface science sample cleaning treatments, e-beam deposition of ultrathin films, and low energy electron diffraction/AES characterization. The sample environment in the polarimeter allows for cryogenic cooling and in-operando application of electric andmore » magnetic fields. The photoelectrons are collected by an electrostatic accelerator and transport lens that form a periaxial beam that is subsequently directed by a Y-shaped electrostatic deflector to either one of the two orthogonal Mott polarimeters. The apparatus has been designed to operate in the extreme conditions of ultraintense single-X-ray pulses as originated by free electron lasers (up to 1 kHz), but it allows also for the single electron counting mode suitable when using statistical sources such as synchrotron radiation, cw-laser, or e-gun beams (up to 150 kcps).« less

Refractory Materials for Flame Deflector Protection System Corrosion Control: Coatings Systems Literature Survey

NASA Technical Reports Server (NTRS)

Calle, Luz M.; Hintze, Paul E.; Parlier, Christopher R.; Sampson, Jeffrey W.; Coffman, Brekke E.; Coffman, Brekke E.; Curran, Jerome P.; Kolody, Mark R.; Whitten, Mary; Perisich, Steven;

Saturn Apollo Program

NASA Image and Video Library

1967-11-01

This is a view of the the first test flight of the Saturn V vehicle (SA-501) at the Kennedy Space Center (KSC) launch complex 39A. The thrust chambers of the first stage's five engines extend into the 45-foot-square hole in the mobile launcher platform. Until liftoff, the flames impinged downward onto a flame deflector that diverted the blast lengthwise in the flame trench. Here, a flame deflector, coated with a black ceramic, is in place below the opening, while a yellow (uncoated) spare deflector rests on its track in the background. It took a tremendous flow of water (28,000 gallons per minute) to cool the flame deflector and trench. The Apollo 4 was launched on November 9, 1967 from KSC.

The new ClusterTrap setup

NASA Astrophysics Data System (ADS)

Martinez, F.; Marx, G.; Schweikhard, L.; Vass, A.; Ziegler, F.

2011-07-01

ClusterTrap has been designed to investigate properties of atomic clusters in the gas phase with particular emphasis on the dependence on the cluster size and charge state. The combination of cluster source, Penning trap and time-of-flight mass spectrometry allows a variety of experimental schemes including collision-induced dissociation, photo-dissociation, further ionization by electron impact, and electron attachment. Due to the storage capability of the trap extended-delay reaction experiments can be performed. Several recent modifications have resulted in an improved setup. In particular, an electrostatic quadrupole deflector allows the coupling of several sources or detectors to the Penning trap. Furthermore, a linear radio-frequency quadrupole trap has been added for accumulation and ion bunching and by switching the potential of a drift tube the kinetic energy of the cluster ions can be adjusted on their way towards or from the Penning trap. Recently, experiments on multiply negatively charged clusters have been resumed.

Optical Simulation and Fabrication of Pancharatnam (Geometric) Phase Devices from Liquid Crystals

NASA Astrophysics Data System (ADS)

Gao, Kun

Pancharatnam made clear the concept of a phase-only device based on changes in the polarization state of light. A device of this type is sometimes called a circular polarization grating because of the polarization states of interfering light beams used to fabricate it by polarization holography. Here, we will call it a Pancharatnam (geometric) phase device to emphasize the fact that the phase of diffracted light does not have a discontinuous periodic profile but changes continuously. In this dissertation, using simulations and experiments, we have successfully demonstrated a 90% diffraction efficiency based on the Pancharatnam phase deflector (PPD) with the dual-twist structure. Unlike the conventional Pancharatnam phase deflector (c-PPD) limited to small diffraction angles, our work demonstrates that a device with a structural periodicity near the wavelength of light is highly efficient at deflecting light to large angles. Also, from a similar fabrication procedure, we have made an ultra-compact non-mechanical zoom lens system based on the Pancharatnam phase lens (PPL) with a low f-number and high efficiency. The wavelength dependence on the image quality is evaluated and shown to be satisfactory from red light to near-infrared machine vision systems. A demonstration device is shown with a 4x zoom ratio at a 633 nm wavelength. The unique characteristic of these devices is made possible through the use of azo-dye photoalignment materials to align a liquid crystal polymer (reactive mesogens). Furthermore, the proposed dual-twist design and fabrication opens the possibility for making a high-efficiency beam-steering device, a lens with an f-number less than 1.0, as well as a wide range of other potential applications in the optical and display industry. The details of simulation, fabrication, and characterization of these devices are shown in this dissertation.

Topology-optimized metasurfaces: impact of initial geometric layout.

PubMed

Yang, Jianji; Fan, Jonathan A

2017-08-15

Topology optimization is a powerful iterative inverse design technique in metasurface engineering and can transform an initial layout into a high-performance device. With this method, devices are optimized within a local design phase space, making the identification of suitable initial geometries essential. In this Letter, we examine the impact of initial geometric layout on the performance of large-angle (75 deg) topology-optimized metagrating deflectors. We find that when conventional metasurface designs based on dielectric nanoposts are used as initial layouts for topology optimization, the final devices have efficiencies around 65%. In contrast, when random initial layouts are used, the final devices have ultra-high efficiencies that can reach 94%. Our numerical experiments suggest that device topologies based on conventional metasurface designs may not be suitable to produce ultra-high-efficiency, large-angle metasurfaces. Rather, initial geometric layouts with non-trivial topologies and shapes are required.

Compact, flexible, frequency agile parametric wavelength converter

DOEpatents

Velsko, Stephan P.; Yang, Steven T.

2002-01-01

This improved Frequency Agile Optical Parametric Oscillator provides near on-axis pumping of a single QPMC with a tilted periodically poled grating to overcome the necessity to find a particular crystal that will permit collinear birefringence in order to obtain a desired tuning range. A tilted grating design and the elongation of the transverse profile of the pump beam in the angle tuning plane of the FA-OPO reduces the rate of change of the overlap between the pumped volume in the crystal and the resonated and non-resonated wave mode volumes as the pump beam angle is changed. A folded mirror set relays the pivot point for beam steering from a beam deflector to the center of the FA-OPO crystal. This reduces the footprint of the device by as much as a factor of two over that obtained when using the refractive telescope design.

Infrasound pulses from lightning and electrostatic field changes: Observation and discussion

NASA Astrophysics Data System (ADS)

Chum, J.; Diendorfer, G.; Å indelářová, T.; Baše, J.; Hruška, F.

2013-10-01

Narrow (~1-2 s) infrasound pulses that followed, with ~11 to ~50 s delays, rapid changes of electrostatic field were observed by a microbarometer array in the Czech Republic during thunderstorm activity. A positive pressure fluctuation (compression phase) always preceded decompression; the compression was usually higher than the decompression. The angles of arrival (azimuth and elevation) were analyzed for selected distinct events. Comparisons of distances and azimuths of infrasound sources from the center of microbarometer array with lightning locations determined by the European Cooperation for Lighting Detection lightning detection network show that most of the selected events can be very likely associated with intracloud (IC) discharges. The preceding rapid changes of electrostatic field, their potential association with IC discharges, and high-elevation angles of arrival for near infrasound sources indicate that an electrostatic mechanism is probably responsible for their generation. It is discussed that distinguishing the relative role of thermal and electrostatic mechanism is difficult and that none of the published models of electrostatic production of infrasound thunder can explain the presented observations precisely. A modification of the current models, based on consideration of at least two charged layers, is suggested. Further theoretical and experimental investigations are however needed to get a better description of the generation mechanism.

7. FLAME DEFLECTOR, VIEW TOWARDS SOUTHWEST. Glenn L. Martin ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. FLAME DEFLECTOR, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

6. FLAME DEFLECTOR, VIEW TOWARDS NORTHWEST. Glenn L. Martin ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. FLAME DEFLECTOR, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

5. SOUTHEAST FLAME DEFLECTOR, VIEW TOWARDS NORTHWEST. Glenn L. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. SOUTHEAST FLAME DEFLECTOR, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

8. NORTH FLAME DEFLECTOR, VIEW TOWARDS WEST. Glenn L. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. NORTH FLAME DEFLECTOR, VIEW TOWARDS WEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Ram-recovery Characteristics of NACA Submerged Inlets at High Subsonic Speeds

NASA Technical Reports Server (NTRS)

Hall, Charles F; Frank, Joseph L

1948-01-01

Results are presented of an experimental investigation of the characteristics of NACA submerged inlets on a model of a fighter airplane for Mach numbers from 0.30 to 0.875. The effects on the ram-recovery ratio at the inlets of Mach number, angle of attack, boundary-layer thickness on the fuselage, inlet location, and boundary-layer deflectors are shown. The data indicate only a slight decrease in ram-recovery ratio for the inlets ahead of or just behind the wing leading edge as Mach number increased, but showed large decreases at high Mach numbers for the inlets aft of the point of maximum thickness of the wing.

Smectic A Filled Birefringent Elements and Fast Switching Twisted Dual Frequency Nematic Cells Used for Digital Light Deflection

NASA Technical Reports Server (NTRS)

Pishnyak, Oleg; Golovin, Andrii; Kreminskia, Liubov; Pouch, John J.; Miranda, Felix A.; Winker, Bruce K.; Lavrentovich, Oleg D.

2006-01-01

We describe the application of smectic A (SmA) liquid crystals for beam deflection. SmA materials can be used in digital beam deflectors (DBDs) as fillers for passive birefringent prisms. SmA prisms have high birefringence and can be constructed in a variety of shapes, including single prisms and prismatic blazed gratings of different angles and profiles. We address the challenges of uniform alignment of SmA, such as elimination of focal conic domains. Fast rotation of the incident light polarization in DBDs is achieved by an electrically switched 90 twisted nematic (TN) cell.

An Experimental Study of Ultra-Wide-Band and Ultra-Wide-Aperture Non-Collinear Acousto-Optic Diffraction in an Optically Biaxial Potassium Arsenate Titanyl Crystal

NASA Astrophysics Data System (ADS)

Milkov, M. G.; Voloshinov, V. B.; Isaenko, L. I.; Vedenyapin, V. N.

2018-01-01

Acousto-optic interaction in an optically biaxial crystalline medium under propagation of light close to one of the optical axes of a potassium arsenate titanyl KTiOAsO4 crystal has been studied. The experimental dependences of the intensity of a diffracted optical beam on the angle of light incidence on an ultrasonic wave have been obtained. It has been shown that a flat cut of a wave-vector surface provides development of an ultra-wide-aperture and ultra-wide-band acousto-optic deflector to control radiation in the visible and infrared electromagnetic spectral ranges.

1. FLAME DEFLECTOR FROM FERROCEMENT APRON, VIEW TOWARDS NORTHEAST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. FLAME DEFLECTOR FROM FERROCEMENT APRON, VIEW TOWARDS NORTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

4. CLOSE UP OF FLAME DEFLECTOR, VIEW TOWARDS SOUTHEAST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. CLOSE UP OF FLAME DEFLECTOR, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

6. FLAME DEFLECTOR AND FERROCEMENT APRON, VIEW TOWARD SOUTHEAST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. FLAME DEFLECTOR AND FERROCEMENT APRON, VIEW TOWARD SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

New functionalities of potassium tantalate niobate deflectors enabled by the coexistence of pre-injected space charge and composition gradient

NASA Astrophysics Data System (ADS)

Zhu, Wenbin; Chao, Ju-Hung; Chen, Chang-Jiang; Campbell, Adrian L.; Henry, Michael G.; Yin, Stuart Shizhuo; Hoffman, Robert C.

2017-10-01

In most beam steering applications such as 3D printing and in vivo imaging, one of the essential challenges has been high-resolution high-speed multi-dimensional optical beam scanning. Although the pre-injected space charge controlled potassium tantalate niobate (KTN) deflectors can achieve speeds in the nanosecond regime, they deflect in only one dimension. In order to develop a high-resolution high-speed multi-dimensional KTN deflector, we studied the deflection behavior of KTN deflectors in the case of coexisting pre-injected space charge and composition gradient. We find that such coexistence can enable new functionalities of KTN crystal based electro-optic deflectors. When the direction of the composition gradient is parallel to the direction of the external electric field, the zero-deflection position can be shifted, which can reduce the internal electric field induced beam distortion, and thus enhance the resolution. When the direction of the composition gradient is perpendicular to the direction of the external electric field, two-dimensional beam scanning can be achieved by harnessing only one single piece of KTN crystal, which can result in a compact, high-speed two-dimensional deflector. Both theoretical analyses and experiments are conducted, which are consistent with each other. These new functionalities can expedite the usage of KTN deflection in many applications such as high-speed 3D printing, high-speed, high-resolution imaging, and free space broadband optical communication.

7. COUNTERFORT, NORTHWEST SIDE OF FLAME DEFLECTOR, VIEW TOWARDS SOUTHEAST. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. COUNTERFORT, NORTHWEST SIDE OF FLAME DEFLECTOR, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

4. DETAIL SHOWING FLAME DEFLECTOR. Looking southeast. Edwards Air ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

4. DETAIL SHOWING FLAME DEFLECTOR. Looking southeast. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Flame Deflector Complete at Launch Complex 39B

NASA Image and Video Library

2018-05-16

Construction is complete on the main flame deflector in the flame trench at Launch Complex 39B at NASA's Kennedy Space Center in Florida. The flame deflector will safely deflect the plume exhaust from NASA's Space Launch System rocket during launch. It will divert the rocket's exhaust, pressure and intense heat to the north at liftoff. The Exploration Ground Systems Program at Kennedy is refurbishing the pad to support the launch of the SLS rocket and Orion on Exploration Mission-1, and helping to transform the space center into a multi-user spaceport.

An ultra-fast EOD-based force-clamp detects rapid biomechanical transitions

NASA Astrophysics Data System (ADS)

Woody, Michael S.; Capitanio, Marco; Ostap, E. Michael; Goldman, Yale E.

2017-08-01

We assembled an ultra-fast infrared optical trapping system to detect mechanical events that occur less than a millisecond after a ligand binds to its filamentous substrate, such as myosin undergoing its 5 - 10 nm working stroke after actin binding. The instrument is based on the concept of Capitanio et al.1, in which a polymer bead-actin-bead dumbbell is held in two force-clamped optical traps. A force applied by the traps causes the filament to move at a constant velocity as hydrodynamic drag balances the applied load. When the ligand binds, the filament motion stops within 100 μs as the total force from the optical traps is transferred to the attachment. Subsequent translations signal active motions, such as the magnitude and timing of the motor's working stroke. In our instrument, the beads defining the dumbbell are held in independent force clamps utilizing a field-programmable gate array (FPGA) to update the trap beam positions at 250 kHz. We found that in our setup, acousto-optical deflectors (AODs) steering the beams were unsuitable for this purpose due to a slightly non-linear response in the beam intensity and deflection angle vs. the AOD ultra-sound wavelength, likely caused by low-amplitude standing acoustic waves in the deflectors. These aberrations caused instability in the force feedback loops leading to artefactual 20 nm jumps in position. This type of AOD non-linearity has been reported to be absent in electro-optical deflectors (EODs)2. We demonstrate that replacement of the AODs with EODs improves the performance of our instrument. Combining the superior beam-steering capability of the EODs, force acquisition via back-plane interferometry, and the dual high-speed FPGA-based feedback loops, we smoothly and precisely apply constant loads to study the dynamics of interactions between biological molecules such as actin and myosin.

Basic surface properties of mononuclear cells from Didelphis marsupialis.

PubMed

Nacife, V P; de Meirelles, M de N; Silva Filho, F C

1998-01-01

The electrostatic surface charge and surface tension of mononuclear cells/monocytes obtained from young and adult marsupials (Didelphis marsupialis) were investigated by using cationized ferritin and colloidal iron hydroxyde, whole cell electrophoresis, and measurements of contact angles. Anionic sites were found distributed throughout the entire investigated cell surfaces. The results revealed that the anionic character of the cells is given by electrostatic charges corresponding to -18.8 mV (cells from young animals) and -29.3 mV (cells from adult animals). The surface electrostatic charge decreased from 10 to 65.2% after treatment of the cells with each one of trypsin, neuraminidase and phospholipase C. The hydrophobic nature of the mononuclear cell surfaces studied by using the contact angle method revealed that both young and adult cells possess cell surfaces of high hidrofilicity since the angles formed with drops of saline water were 42.5 degrees and 40.8 degrees, respectively. Treatment of the cells with trypsin or neuraminidase rendered their surfaces more hydrophobic, suggesting that sialic acid-containing glycoproteins are responsible for most of the hydrophilicity observed in the mononuclear cell surfaces from D. marsupialis.

2. CLOSE UP OF FLAME DEFLECTOR FROM FERROCEMENT APRON, VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. CLOSE UP OF FLAME DEFLECTOR FROM FERROCEMENT APRON, VIEW TOWARDS NORTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

2. FLAME DEFLECTOR FROM THE REINFORCED CONCRETE SLAB ROOF, VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. FLAME DEFLECTOR FROM THE REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

9. FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

9. FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

3. SOUTH FLAME DEFLECTOR FROM THE REINFORCED CONCRETE ROOF, VIEW ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. SOUTH FLAME DEFLECTOR FROM THE REINFORCED CONCRETE ROOF, VIEW TOWARDS EAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

22. UPPER STATION, LOWER FLOOR, MOTOR ROOM, VERTICAL DEFLECTOR SHEAVE, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

22. UPPER STATION, LOWER FLOOR, MOTOR ROOM, VERTICAL DEFLECTOR SHEAVE, MOTORS. - Monongahela Incline Plane, Connecting North side of Grandview Avenue at Wyoming Street with West Carson Street near Smithfield Street, Pittsburgh, Allegheny County, PA

23. UPPER STATION, LOWER FLOOR, MOTOR ROOM, VERTICAL DEFLECTOR SHEAVE, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

23. UPPER STATION, LOWER FLOOR, MOTOR ROOM, VERTICAL DEFLECTOR SHEAVE, MOTORS. - Monongahela Incline Plane, Connecting North side of Grandview Avenue at Wyoming Street with West Carson Street near Smithfield Street, Pittsburgh, Allegheny County, PA

1. FLAME DEFLECTOR AT LEFT, COUNTERFORT AT RIGHT, VIEW TOWARDS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

1. FLAME DEFLECTOR AT LEFT, COUNTERFORT AT RIGHT, VIEW TOWARDS SOUTH. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

6. FLAME DEFLECTOR AT LEFT, COUNTERFORT AT RIGHT, VIEW TOWARDS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. FLAME DEFLECTOR AT LEFT, COUNTERFORT AT RIGHT, VIEW TOWARDS EAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Numerical simulation of interaction between chemically active exhaust and a jet blast deflector

NASA Astrophysics Data System (ADS)

Korotaeva, T. A.; Turchinovich, A. O.

2017-10-01

The interaction of chemically active exhausts of aircraft engines with jet blast deflector (JBD) of various configurations has been considered at the stage of ground run procedure. The problem is modeled in the 3-D approximation in the framework of the numerical solution of the Navier-Stokes equations taking into account the kinetic model of the interaction of between the components of engine exhaust and air. A complex field of gasdynamic flow that is realized when jets emerge from nozzles and interact with each other, with air, with a gas deflector has been studied. The main purpose of the study is to prove the concept that it is possible to generate a vortex flow that can not only change the direction of the jets, but also contribute to the lifting of the mass of pollutants and their dispersion in the atmosphere using a gas deflector shape.

Numerical Investigation of Different Radial Inlet Forms for Centrifugal Compressor and Influence of the Deflectors Number by Means of Computational Fluid Dynamics Methods with Computational Model Validation

NASA Astrophysics Data System (ADS)

Kozhukhov, Y. V.; Yun, V. K.; Reshetnikova, L. V.; Prokopovich, M. V.

2015-08-01

The goal of this work is numerical experiments for five different types of the centrifugal compressor's inlet chambers with the help of CFD-methods and comparison of the computational results with the results of the real experiment which was held in the Nevskiy Lenin Plant in Saint-Petersburg. In the context of one of the chambers the influence of deflectors on its characteristics was investigated. The objects of investigation are 5 inlet chambers of different types which differ from each other by deflectors’ existence and by its number. The comparative analyze of the results of numerical and real experiments was held by means of comparison of relative velocity and static pressure coefficient distribution on hub and shroud region, and also by means of loss coefficient values change for all five chambers. As a result of the numerical calculation the quantitative and qualitative departure of CFD- calculations results and real experiment were found out. The investigation of the influence of the number of deflectors on flow parameters was carried out. The results of the study prove that the presence of the deflectors on flow path significantly increases the probability of the flow separations and reversed flows appearance on them. At the same time, the complete absence of the deflectors in the chamber significantly increases circumferential distortion of the flow; however the loss coefficient decreases anyway, the high values of which are caused by the shock flow existence. Thus, the profiling of the deflectors of the inlet chamber should be given a special attention.

Beam energy tracking system on Optima XEx high energy ion implanter

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

David, Jonathan; Satoh, Shu; Wu Xiangyang

2012-11-06

The Axcelis Optima XEx high energy implanter is an RF linac-based implanter with 12 RF resonators for beam acceleration. Even though each acceleration field is an alternating, sinusoidal RF field, the well known phase-focusing principle produces a beam with a sharp quasi-monoenergetic energy spectrum. A magnetic energy filter after the linac further attenuates the low energy continuum in the energy spectrum often associated with RF acceleration. The final beam energy is a function of the phase and amplitude of the 12 resonators in the linac. When tuning a beam, the magnetic energy filter is set to the desired energy, andmore » each linac parameter is tuned to maximize the transmission through the filter. Once a beam is set up, all the parameters are stored in a recipe, which can be easily tuned and has proven to be quite repeatable. The magnetic field setting of the energy filter selects the beam energy from the RF Linac accelerator, and in-situ verification of beam energy in addition to the magnetic energy filter setting has long been desired. An independent energy tracking system was developed for this purpose, using the existing electrostatic beam scanner as a deflector to construct an in-situ electrostatic energy analyzer. This paper will describe the system and performance of the beam energy tracking system.« less

3. FLAME DEFLECTOR AT CENTER, CONNECTING TUNNEL AT CENTER RIGHT, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. FLAME DEFLECTOR AT CENTER, CONNECTING TUNNEL AT CENTER RIGHT, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

5. CLOSE UP OF FLAME DEFLECTOR, COUNTERFORT VISIBLE AT REAR, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. CLOSE UP OF FLAME DEFLECTOR, COUNTERFORT VISIBLE AT REAR, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

11. REINFORCED CONCRETE SLAB ROOF, FLAME DEFLECTOR AT RIGHT, CONTROL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

11. REINFORCED CONCRETE SLAB ROOF, FLAME DEFLECTOR AT RIGHT, CONTROL BUILDING B AT FAR CENTER RIGHT. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

7. REINFORCED CONCRETE SLAB ROOF FROM NORTHWEST EDGE, FLAME DEFLECTOR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

7. REINFORCED CONCRETE SLAB ROOF FROM NORTHWEST EDGE, FLAME DEFLECTOR AT RIGHT, VIEW TOWARDS SOUTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

3. FLAME DEFLECTOR AT UPPER LEFT, FERROCEMENT APRON CONTROLS AT ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. FLAME DEFLECTOR AT UPPER LEFT, FERROCEMENT APRON CONTROLS AT LOWER RIGHT, VIEW TOWARDS NORTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-4, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Properties of Refractory Concrete in Tension and Compression

NASA Technical Reports Server (NTRS)

Sampson, Jeffrey

2009-01-01

Refractory concrete on the LC-39A Flame Deflector has been damaged during multiple Space Shuttle launches (e.g. STS-124, STS-126, STS-119, and STS-125, STS-127). These events have prompted a better understanding of the system via an analytical model of the Flame Deflector assembly to include the Fondu Fyre refractory concrete. This model requires test data inputs of the refractory concrete's mechanical properties, which include stress versus strain curves in tension and compression, modulus of elasticity, and Poisson's ratio. Sections of Fondu Fyre refractory concrete removed from the LC-39A Flame Deflector were provided for this testing.

Angle performance on optima MDxt

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

David, Jonathan; Kamenitsa, Dennis

2012-11-06

Angle control on medium current implanters is important due to the high angle-sensitivity of typical medium current implants, such as halo implants. On the Optima MDxt, beam-to-wafer angles are controlled in both the horizontal and vertical directions. In the horizontal direction, the beam angle is measured through six narrow slits, and any angle adjustment is made by electrostatically steering the beam, while cross-wafer beam parallelism is adjusted by changing the focus of the electrostatic parallelizing lens (P-lens). In the vertical direction, the beam angle is measured through a high aspect ratio mask, and any angle adjustment is made by slightlymore » tilting the wafer platen prior to implant. A variety of tests were run to measure the accuracy and repeatability of Optima MDxt's angle control. SIMS profiles of a high energy, channeling sensitive condition show both the cross-wafer angle uniformity, along with the small-angle resolution of the system. Angle repeatability was quantified by running a channeling sensitive implant as a regular monitor over a seven month period and measuring the sheet resistance-to-angle sensitivity. Even though crystal cut error was not controlled for in this case, when attributing all Rs variation to angle changes, the overall angle repeatability was measured as 0.16 Degree-Sign (1{sigma}). A separate angle repeatability test involved running a series of V-curves tests over a four month period using low crystal cut wafers selected from the same boule. The results of this test showed the angle repeatability to be <0.1 Degree-Sign (1{sigma}).« less

6. DETAIL OF NORTH ELEVATION AND FOOTINGS FOR FLAME DEFLECTOR, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. DETAIL OF NORTH ELEVATION AND FOOTINGS FOR FLAME DEFLECTOR, NOW MISSING. Looking east. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-5, Test Area 1-115, northwest end of Saturn Boulevard, Boron, Kern County, CA

2. FLAME DEFLECTOR AT RIGHT, COUNTERFORT AT CENTER, FRAGMENT OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. FLAME DEFLECTOR AT RIGHT, COUNTERFORT AT CENTER, FRAGMENT OF CONCRETE CAMERA STAND IN FOREGROUND, VIEW TOWARDS SOUTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

8. WEST FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, FORMER ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. WEST FLAME DEFLECTOR FROM REINFORCED CONCRETE SLAB ROOF, FORMER DRAINAGE AREA IN THE DISTANCE, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-1, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

24. UPPER STATION, LOWER FLOOR, MOTOR ROOM, OFF VERTICAL DEFLECTOR ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

24. UPPER STATION, LOWER FLOOR, MOTOR ROOM, OFF VERTICAL DEFLECTOR SHEAVE, MOTOR, BRAKE, PINION SHAFT, DRIVE WHEEL. - Monongahela Incline Plane, Connecting North side of Grandview Avenue at Wyoming Street with West Carson Street near Smithfield Street, Pittsburgh, Allegheny County, PA

3. FLAME DEFLECTOR AT LEFT, COUNTERFORT AT RIGHT, CONTROL BUILDING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

3. FLAME DEFLECTOR AT LEFT, COUNTERFORT AT RIGHT, CONTROL BUILDING B AT UPPER LEFT, VIEW TOWARDS NORTHWEST. - Glenn L. Martin Company, Titan Missile Test Facilities, CaptiveTest Stand D-3, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

The effect of clulstering of galaxies on the statistics of gravitational lenses

NASA Technical Reports Server (NTRS)

Anderson, N.; Alcock, C.

1986-01-01

It is examined whether clustering of galaxies can significantly alter the statistical properties of gravitational lenses? Only models of clustering that resemble the observed distribution of galaxies in the properties of the two-point correlation function are considered. Monte-Carlo simulations of the imaging process are described. It is found that the effect of clustering is too small to be significant, unless the mass of the deflectors is so large that gravitational lenses become common occurrences. A special model is described which was concocted to optimize the effect of clustering on gravitational lensing but still resemble the observed distribution of galaxies; even this simulation did not satisfactorily produce large numbers of wide-angle lenses.

Reintroducing electrostatics into macromolecular crystallographic refinement: application to neutron crystallography and DNA hydration.

PubMed

Fenn, Timothy D; Schnieders, Michael J; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S; Brunger, Axel T

2011-04-13

Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints, and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here, we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen-bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. Copyright © 2011 Elsevier Ltd. All rights reserved.

Reintroducing Electrostatics into Macromolecular Crystallographic Refinement: Application to Neutron Crystallography and DNA Hydration

PubMed Central

Fenn, Timothy D.; Schnieders, Michael J.; Mustyakimov, Marat; Wu, Chuanjie; Langan, Paul; Pande, Vijay S.; Brunger, Axel T.

2011-01-01

Summary Most current crystallographic structure refinements augment the diffraction data with a priori information consisting of bond, angle, dihedral, planarity restraints and atomic repulsion based on the Pauli exclusion principle. Yet, electrostatics and van der Waals attraction are physical forces that provide additional a priori information. Here we assess the inclusion of electrostatics for the force field used for all-atom (including hydrogen) joint neutron/X-ray refinement. Two DNA and a protein crystal structure were refined against joint neutron/X-ray diffraction data sets using force fields without electrostatics or with electrostatics. Hydrogen bond orientation/geometry favors the inclusion of electrostatics. Refinement of Z-DNA with electrostatics leads to a hypothesis for the entropic stabilization of Z-DNA that may partly explain the thermodynamics of converting the B form of DNA to its Z form. Thus, inclusion of electrostatics assists joint neutron/X-ray refinements, especially for placing and orienting hydrogen atoms. PMID:21481775

Wide-band acousto-optic deflectors for large field of view two-photon microscope.

PubMed

Jiang, Runhua; Zhou, Zhenqiao; Lv, Xiaohua; Zeng, Shaoqun

2012-04-01

Acousto-optic deflector (AOD) is an attractive scanner for two-photon microscopy because it can provide fast and versatile laser scanning and does not involve any mechanical movements. However, due to the small scan range of available AOD, the field of view (FOV) of the AOD-based microscope is typically smaller than that of the conventional galvanometer-based microscope. Here, we developed a novel wide-band AOD to enlarge the scan angle. Considering the maximum acceptable acoustic attenuation in the acousto-optic crystal, relatively lower operating frequencies and moderate aperture were adopted. The custom AOD was able to provide 60 MHz 3-dB bandwidth and 80% peak diffraction efficiency at 840 nm wavelength. Based on a pair of such AOD, a large FOV two-photon microscope was built with a FOV up to 418.5 μm (40× objective). The spatiotemporal dispersion was compensated simultaneously with a single custom-made prism. By means of dynamic power modulation, the variation of laser intensity within the FOV was reduced below 5%. The lateral and axial resolution of the system were 0.58-2.12 μm and 2.17-3.07 μm, respectively. Pollen grain images acquired by this system were presented to demonstrate the imaging capability at different positions across the entire FOV. © 2012 American Institute of Physics

Aerodynamic flow deflector to increase large scale wind turbine power generation by 10%.

DOT National Transportation Integrated Search

2015-11-01

The innovation proposed in this paper has the potential to address both the efficiency demands of wind farm owners as well as to provide a disruptive design innovation to turbine manufacturers. The aerodynamic deflector technology was created to impr...

Electro-optic KTN Devices

NASA Astrophysics Data System (ADS)

Yagi, Shogo; Fujiura, Kazuo

We have grown KTN crystals with optical quality, and developed high-speed beam deflectors and variable focal length lenses based on KTN's large electro-optic effect.　Furthermore, by using the KTN beam deflectors, we have developed a swept light source for OCT operable at 200 kHz.

CLASHING BEAM PARTICLE ACCELERATOR

DOEpatents

Burleigh, R.J.

1961-04-11

A charged-particle accelerator of the proton synchrotron class having means for simultaneously accelerating two separate contra-rotating particle beams within a single annular magnet structure is reported. The magnet provides two concentric circular field regions of opposite magnetic polarity with one field region being of slightly less diameter than the other. The accelerator includes a deflector means straddling the two particle orbits and acting to collide the two particle beams after each has been accelerated to a desired energy. The deflector has the further property of returning particles which do not undergo collision to the regular orbits whereby the particles recirculate with the possibility of colliding upon subsequent passages through the deflector.

2. NORTH FRONT, FROM SUPERSTRUCTURE TO FLAME DEFLECTOR. Looking south ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

2. NORTH FRONT, FROM SUPERSTRUCTURE TO FLAME DEFLECTOR. Looking south southwest from Observation Post No. 1 (Building 8767). - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

5. FLAME DEFLECTOR, COMPLETE X15 VEHICLE TEST STAND. Looking east. ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. FLAME DEFLECTOR, COMPLETE X-15 VEHICLE TEST STAND. Looking east. - Edwards Air Force Base, X-15 Engine Test Complex, Rocket Engine & Complete X-15 Vehicle Test Stands, Rogers Dry Lake, east of runway between North Base & South Base, Boron, Kern County, CA

5. FLAME DEFLECTOR AT LEFT, FERROCEMENT APRON AT RIGHT CENTER, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. FLAME DEFLECTOR AT LEFT, FERROCEMENT APRON AT RIGHT CENTER, CONTROL BUILDING A AT FAR RIGHT, CONNECTING TUNNEL AT UPPER CENTER, VIEW TOWARDS NORTHEAST. - Glenn L. Martin Company, Titan Missile Test Facilities, Captive Test Stand D-2, Waterton Canyon Road & Colorado Highway 121, Lakewood, Jefferson County, CO

Extended-range tiltable micromirror

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

Allen, James J; Wiens, Gloria J; Bronson, Jessica R

A tiltable micromirror device is disclosed in which a micromirror is suspended by a progressive linkage with an electrostatic actuator (e.g. a vertical comb actuator or a capacitive plate electrostatic actuator) being located beneath the micromirror. The progressive linkage includes a pair of torsion springs which are connected together to operate similar to a four-bar linkage with spring joints. The progressive linkage provides a non-linear spring constant which can allow the micromirror to be tilted at any angle within its range substantially free from any electrostatic instability or hysteretic behavior.

High frame-rate en face optical coherence tomography system using KTN optical beam deflector

NASA Astrophysics Data System (ADS)

Ohmi, Masato; Shinya, Yusuke; Imai, Tadayuki; Toyoda, Seiji; Kobayashi, Junya; Sakamoto, Tadashi

2017-02-01

We developed high frame-rate en face optical coherence tomography (OCT) system using KTa1-xNbxO3 (KTN) optical beam deflector. In the imaging system, the fast scanning was performed at 200 kHz by the KTN optical beam deflector, while the slow scanning was performed at 800 Hz by the galvanometer mirror. As a preliminary experiment, we succeeded in obtaining en face OCT images of human fingerprint with a frame rate of 800 fps. This is the highest frame-rate obtained using time-domain (TD) en face OCT imaging. The 3D-OCT image of sweat gland was also obtained by our imaging system.

Development of novel high-speed en face optical coherence tomography system using KTN optical beam deflector

NASA Astrophysics Data System (ADS)

Ohmi, Masato; Fukuda, Akihiro; Miyazu, Jun; Ueno, Masahiro; Toyoda, Seiji; Kobayashi, Junya

2015-02-01

We developed a novel high-speed en face optical coherence tomography (OCT) system using a KTa1-xNbxO3 (KTN) optical beam deflector. Using the imaging system, fast scanning was performed at 200 kHz by the KTN beam deflector, while slow scanning was performed at 400 Hz by the galvanometer mirror. In a preliminary experiment, we obtained en face OCT images of a human fingerprint at 400 fps. This is the highest speed reported in time-domain en face OCT imaging and is comparable to the speed of swept-source OCT. A 3D-OCT image of a sweat gland was also obtained by our imaging system.

50 CFR Figures 19a and 19b to Part... - Chauvin Shrimp Deflector Installation Details

Code of Federal Regulations, 2012 CFR

2012-10-01

... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Chauvin Shrimp Deflector Installation Details 19a Figures 19a and 19b to Part 223 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS THREATENED MARINE...

Pneumafil casing blower through moving reference frame (MRF) - A CFD simulation

NASA Astrophysics Data System (ADS)

Manivel, R.; Vijayanandh, R.; Babin, T.; Sriram, G.

2018-05-01

In this analysis work, the ring frame of Pneumafil casing blower of the textile mills with a power rating of 5 kW have been simulated using Computational Fluid Dynamics (CFD) code. The CFD analysis of the blower is carried out in Ansys Workbench 16.2 with Fluent using MRF solver settings. The simulation settings and boundary conditions are based on literature study and field data acquired. The main objective of this work is to reduce the energy consumption of the blower. The flow analysis indicated that the power consumption is influenced by the deflector plate orientation and deflector plate strip situated at the outlet casing of the blower. The energy losses occurred in the blower is due to the recirculation zones formed around the deflector plate strip. The deflector plate orientation is changed and optimized to reduce the energy consumption. The proposed optimized model is based on the simulation results which had relatively lesser power consumption than the existing and other cases. The energy losses in the Pneumafil casing blower are reduced through CFD analysis.

Ion mass spectrometer

NASA Technical Reports Server (NTRS)

Neugebauer, M. (Inventor); Clay, D. R.; Goldstein, B. E.; Goldstein, R.

1984-01-01

An ion mass spectrometer is described which detects and indicates the characteristics of ions received over a wide angle, and which indicates the mass to charge ratio, the energy, and the direction of each detected ion. The spectrometer includes a magnetic analyzer having a sector magnet that passes ions received over a wide angle, and an electrostatic analyzer positioned to receive ions passing through the magnetic analyzer. The electrostatic analyzer includes a two dimensional ion sensor at one wall of the analyzer chamber, that senses not only the lengthwise position of the detected ion to indicate its mass to charge ratio, but also detects the ion position along the width of the chamber to indicate the direction in which the ion was traveling.

Hanging angles of two electrostatically repelling pith balls of different masses

NASA Astrophysics Data System (ADS)

Tran, Phuc G.; Mungan, Carl E.

2011-09-01

An analytic solution can be derived for the angles of two mutually repelling charged pith balls of unequal mass hanging from strings from a common point of attachment. Just as in the equal-mass case, a cubic equation is found for the square of the sine of either angle, and an approximation can be used to avoid Cardano's formula for small angles. These results extend a standard problem treated in introductory undergraduate courses in electricity and magnetism.

Prefabricated Refractory Panels for Use in KSC's Flame Deflectors: A Feasibility Study

NASA Technical Reports Server (NTRS)

Calle, Luz Maria; Trejo, David

2010-01-01

The launch complexes at the John F. Kennedy Space Center (KSC) have been used to launch space vehicles for the Apollo and Space Shuttle programs. NASA is currently designing and developing a new space vehicle. The launch complexes have been in service for a significant duration and the aggressive conditions of the Florida coast and the launches have resulted in failures within the launch complexes. Of particular interests is the performance of the refractory lining that covers the steel base structure for the diversion of the exhaust from the launched vehicles (i.e., the flame deflectors). An unprotected steel base structure would likely experience loss of strength and possible failure when subjected to the high temperatures during launches. The refractory lining is critical for successful launches. The refractory material currently used in the flame trenches was developed in 1959 and is the only refractory material approved for use in these facilities. Significant effort and costs are expended in repairing the lining system after each launch. NASA is currently performing a comprehensive research program to assess and develop refractory materials for improved performance in the flame trenches. However, one challenge associated with the use of refractory materials in the flame trench is that the materials should be cured, dried, and fired to maximize their properties and characteristics. Because of the large size of the deflectors and trenches, drying and firing of the lining system is difficult, if not impossible. Most refractory materials are dried and fired before use. Because the refractory materials used for the deflector lining cannot be dried and fired, the full potential of the materials are not being realized. A system that could use refractory materials that could be cured, dried, and sintered in a controlled environment would likely improve the performance of the lining system. This report evaluates the feasibility of fabricating and placing prefabricated refractory panels on the deflector. Panels could be fabricated and processed off-site in a controlled environment to maximize performance. These panels could then be transported to KSC and installed on the flame deflector. The findings of this report indicate that conventionally reinforced, prefabricated refractory panels can likely be designed, fabricated, and placed on the deflector. Post-tensioning of the panels will reduce the amount of "open' joints, which can be susceptible to accelerated erosion and abrasion. The panels, produced with newer, better performing refractory materials, should exhibit lower deterioration, providing a more economical system. A method for placing the panels has been provided. The findings of this research indicate that post-tensioned, prefabricated refractory panels can be placed on the flame deflectors and should exhibit improved performance when compared with the current method of gunning the refractories on the deflector. Further evaluation will be needed to confirm these findings. Specific focus should be placed on the performance of the joints transverse to the exhaust flow, erosion/abrasion rates of "closed" joints, uplift forces at joints transverse to the exhaust flow, development of composite action between the steel base and the refractory panels, and refractory material resistance to the launch and Florida coast environment.

27. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

27. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH LABORATORY, BUILDING 25C, WHICH REPLACED THE 10-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

26. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

26. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH LABORATORY, BUILDING 25C, WHICH REPLACED THE 10-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

28. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. VIEW OF EXHAUST AND DEFLECTOR FOR SUBSONIC AERODYNAMICS RESEARCH LABORATORY, BUILDING 25C, WHICH REPLACED THE 10-FOOT WIND TUNNEL (1991). - Wright-Patterson Air Force Base, Area B, Buildings 25 & 24,10-foot & 20-foot Wind Tunnel Complex, Northeast side of block bounded by K, G, Third, & Fifth Streets, Dayton, Montgomery County, OH

A spatio-temporally compensated acousto-optic scanner for two-photon microscopy providing large field of view.

PubMed

Kremer, Y; Léger, J-F; Lapole, R; Honnorat, N; Candela, Y; Dieudonné, S; Bourdieu, L

2008-07-07

Acousto-optic deflectors (AOD) are promising ultrafast scanners for non-linear microscopy. Their use has been limited until now by their small scanning range and by the spatial and temporal dispersions of the laser beam going through the deflectors. We show that the use of AOD of large aperture (13mm) compared to standard deflectors allows accessing much larger field of view while minimizing spatio-temporal distortions. An acousto-optic modulator (AOM) placed at distance of the AOD is used to compensate spatial and temporal dispersions. Fine tuning of the AOM-AOD setup using a frequency-resolved optical gating (GRENOUILLE) allows elimination of pulse front tilt whereas spatial chirp is minimized thanks to the large aperture AOD.

Modeling of Heat Transfer and Ablation of Refractory Material Due to Rocket Plume Impingement

NASA Technical Reports Server (NTRS)

Harris, Michael F.; Vu, Bruce T.

2012-01-01

CR Tech's Thermal Desktop-SINDA/FLUINT software was used in the thermal analysis of a flame deflector design for Launch Complex 39B at Kennedy Space Center, Florida. The analysis of the flame deflector takes into account heat transfer due to plume impingement from expected vehicles to be launched at KSC. The heat flux from the plume was computed using computational fluid dynamics provided by Ames Research Center in Moffet Field, California. The results from the CFD solutions were mapped onto a 3-D Thermal Desktop model of the flame deflector using the boundary condition mapping capabilities in Thermal Desktop. The ablation subroutine in SINDA/FLUINT was then used to model the ablation of the refractory material.

Magnetic and electric deflector spectrometers for ion emission analysis from laser generated plasma

NASA Astrophysics Data System (ADS)

Torrisi, Lorenzo; Costa, Giuseppe; Ceccio, Giovanni; Cannavò, Antonino; Restuccia, Nancy; Cutroneo, Mariapompea

2018-01-01

The pulsed laser-generated plasma in vacuum and at low and high intensities can be characterized using different physical diagnostics. The charge particles emission can be characterized using magnetic, electric and magnet-electrical spectrometers. Such on-line techniques are often based on time-of-flight (TOF) measurements. A 90° electric deflection system is employed as ion energy analyzer (IEA) acting as a filter of the mass-to-charge ratio of emitted ions towards a secondary electron multiplier. It determines the ion energy and charge state distributions. The measure of the ion and electron currents as a function of the mass-to-charge ratio can be also determined by a magnetic deflector spectrometer, using a magnetic field of the order of 0.35 T, orthogonal to the ion incident direction, and an array of little ion collectors (IC) at different angles. A Thomson parabola spectrometer, employing gaf-chromix as detector, permits to be employed for ion mass, energy and charge state recognition. Mass quadrupole spectrometry, based on radiofrequency electric field oscillations, can be employed to characterize the plasma ion emission. Measurements performed on plasma produced by different lasers, irradiation conditions and targets are presented and discussed. Complementary measurements, based on mass and optical spectroscopy, semiconductor detectors, fast CCD camera and Langmuir probes are also employed for the full plasma characterization. Simulation programs, such as SRIM, SREM, and COMSOL are employed for the charge particle recognition.

Heating of ions to superthermal energies in the topside ionosphere by electrostatic ion cyclotron waves

NASA Technical Reports Server (NTRS)

Ungstrup, E.; Klumpar, D. M.; Heikkila, W. J.

1979-01-01

The soft particle spectrometer on the Isis 2 spacecraft occasionally observes fluxes of ions moving upward out of the ionosphere in the vicinity of the auroral oval. These ion fluxes are characterized by a sharp pitch angle distribution usually peaked at an angle somewhat greater than 90 deg, indicative of particles heated to a large transverse temperature in a narrow range below the spacecraft. The observations are interpreted in terms of electrostatic ion cyclotron waves, which heat the ions to superthermal energies transverse to the earth's magnetic field. When the transverse energy increases, the repulsive force of the earth's magnetic field, proportional to the particle magnetic moment, repels the particles away from the earth.

Effects of turbulence on a kinetic auroral arc model

NASA Technical Reports Server (NTRS)

Cornwall, J. M.; Chiu, Y. T.

1981-01-01

A plasma kinetic model of an inverted-V auroral arc structure which includes the effects of electrostatic turbulence is proposed. In the absence of turbulence, a parallel potential drop is supported by magnetic mirror forces and charge quasi neutrality, with energetic auroral ions penetrating to low altitudes; relative to the electrons, the ions' pitch angle distribution is skewed toward smaller pitch angles. The electrons energized by the potential drop form a current which excites electrostatic turbulence. In equilibrium the plasma is marginally stable. The conventional anomalous resistivity contribution to the potential drop is very small. Anomalous resistivity processes are far too dissipative to be powered by auroral particles. It is concluded that under certain circumstances equilibrium may be impossible and relaxation oscillations set in.

Particle trap for compressed gas insulated transmission systems

DOEpatents

Cookson, A.H.

1984-04-26

A particle trap is provided for gas insulated transmission lines having a central high voltage conductor supported within an outer coaxial conductive sheath by a dielectric support member. A cavity between the inner conductor and outer sheath is filled with a dielectric insulating gas. A cone-like particle deflector, mounted to the inner conductor, deflects moving particles away from the support member, to radially outer portions of the cavity. A conductive shield is disposed adjacent the outer sheath to form a field-free region in radially outer portions of the cavity, between the shield and the sheath. Particles traveling along the cavity are deflected by the cone-like deflector into the field-free region where they are held immobile. In a vertical embodiment, particles enter the field-free region through an upper end of a gap formed between shield and sheath members. In a horizontal embodiment, the deflector cone has a base which is terminated radially internally of the shield. Apertures in the shield located adjacent the deflector allow passage of deflected particles into the field-free region. The dielectric support member is thereby protected from contaminating particles that may otherwise come to rest thereon.

Particle trap for compressed gas insulated transmission systems

DOEpatents

Cookson, Alan H.

1985-01-01

A particle trap is provided for gas insulated transmission lines having a central high voltage conductor supported within an outer coaxial conductive sheath by a dielectric support member. A cavity between the inner conductor and outer sheath is filled with a dielectric insulating gas. A cone-like particle deflector, mounted to the inner conductor, deflects moving particles away from the support member, to radially outer portions of the cavity. A conductive shield is disposed adjacent the outer sheath to form a field-free region in radially outer portions of the cavity, between the shield and the sheath. Particles traveling along the cavity are deflected by the cone-like deflector into the field-free region where they are held immobile. In a vertical embodiment, particles enter the field-free region through an upper end of a gap formed between shield and sheath members. In a horizontal embodiment, the deflector cone has a base which is terminated radially internally of the shield. Apertures in the shield located adjacent the deflector allow passage of deflected particles into the field-free region. The dielectric support member is thereby protected from contaminating particles that may otherwise come to rest thereon.

Filtered cathodic arc deposition apparatus and method

DOEpatents

Krauss, Alan R.

1999-01-01

A filtered cathodic arc deposition method and apparatus for the production of highly dense, wear resistant coatings which are free from macro particles. The filtered cathodic arc deposition apparatus includes a cross shaped vacuum chamber which houses a cathode target having an evaporable surface comprised of the coating material, means for generating a stream of plasma, means for generating a transverse magnetic field, and a macro particle deflector. The transverse magnetic field bends the generated stream of plasma in the direction of a substrate. Macro particles are effectively filtered from the stream of plasma by traveling, unaffected by the transverse magnetic field, along the initial path of the plasma stream to a macro particle deflector. The macro particle deflector has a preformed surface which deflects macro particles away from the substrate.

Accurate Simulation of Parametrically Excited Micromirrors via Direct Computation of the Electrostatic Stiffness

PubMed Central

Frangi, Attilio; Guerrieri, Andrea; Boni, Nicoló

2017-01-01

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches of the mirror response, we implement a simplified continuation method with arc-length control and propose an innovative technique based on Finite Elements and the concepts of material derivative in order to compute the electrostatic stiffness; i.e., the derivative of the torque with respect to the torsional angle, as required by the continuation approach. PMID:28383483

Accurate Simulation of Parametrically Excited Micromirrors via Direct Computation of the Electrostatic Stiffness.

PubMed

Frangi, Attilio; Guerrieri, Andrea; Boni, Nicoló

2017-04-06

Electrostatically actuated torsional micromirrors are key elements in Micro-Opto-Electro- Mechanical-Systems. When forced by means of in-plane comb-fingers, the dynamics of the main torsional response is known to be strongly non-linear and governed by parametric resonance. Here, in order to also trace unstable branches of the mirror response, we implement a simplified continuation method with arc-length control and propose an innovative technique based on Finite Elements and the concepts of material derivative in order to compute the electrostatic stiffness; i.e., the derivative of the torque with respect to the torsional angle, as required by the continuation approach.

PLZT Ceramic Driving Rotary Micro-mirror Based on Photoelectric-electrostatic Mechanism

NASA Astrophysics Data System (ADS)

Tang, Yujuan; Yang, Zhong; Chen, Yusong; Wang, Xinjie

2017-12-01

Based on the anomalous photovoltaic effect of PLZT, a rotary micro-mirror driven by hybrid photoelectric-electrostatic actuation of PLZT ceramic is proposed. Firstly, the mathematical modelling of coupled multi-physics fields of PLZT ceramic is established during illumination and light off phases. Then, the relationship between the rotation angle and the photovoltage of PLZT ceramics is established. In addition, the feasibility of rotary micro-mirror with hybrid photoelectric-electrostatic driving is verified via closed-loop control for photo-induced voltage of PLZT ceramic. The experimental results show that the photo-induced voltage of PLZT ceramics has good dynamic control precision using on-off closed-loop control method.

Method and system for treating an interior surface of a workpiece using a charged particle beam

DOEpatents

Swenson, David Richard

2007-05-23

A method and system of treating an interior surface on an internal cavity of a workpiece using a charged particle beam. A beam deflector surface of a beam deflector is placed within the internal cavity of the workpiece and is used to redirect the charged particle beam toward the interior surface to treat the interior surface.

2-Dimensional beamsteering using dispersive deflectors and wavelength tuning.

PubMed

Chan, Trevor; Myslivets, Evgeny; Ford, Joseph E

2008-09-15

We introduce a 2D beamscanner which is controlled by wavelength tuning. Two passive dispersive devices are aligned orthogonally to deflect the optical beam in two dimensions. We provide a proof of principle demonstration by combining an arrayed waveguide grating with a free space optical grating and using various input sources to characterize the beamscanner. This achieved a discrete 10.3 degrees by 11 degrees output field of view with attainable angles existing on an 8 by 6 grid of directions. The entire range was reached by scanning over a 40 nm wavelength range. We also analyze an improved system combining a virtually imaged phased array with a diffraction grating. This device is much more compact and produces a continuous output scan in one direction while being discrete in the other.

Optima MDxt: A high throughput 335 keV mid-dose implanter

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

Eisner, Edward; David, Jonathan; Justesen, Perry

2012-11-06

The continuing demand for both energy purity and implant angle control along with high wafer throughput drove the development of the Axcelis Optima MDxt mid-dose ion implanter. The system utilizes electrostatic scanning, an electrostatic parallelizing lens and an electrostatic energy filter to produce energetically pure beams with high angular integrity. Based on field proven components, the Optima MDxt beamline architecture offers the high beam currents possible with singly charged species including arsenic at energies up to 335 keV as well as large currents from multiply charged species at energies extending over 1 MeV. Conversely, the excellent energy filtering capability allowsmore » high currents at low beam energies, since it is safe to utilize large deceleration ratios. This beamline is coupled with the >500 WPH capable endstation technology used on the Axcelis Optima XEx high energy ion implanter. The endstation includes in-situ angle measurements of the beam in order to maintain excellent beam-to-wafer implant angle control in both the horizontal and vertical directions. The Optima platform control system provides new generation dose control system that assures excellent dosimetry and charge control. This paper will describe the features and technologies that allow the Optima MDxt to provide superior process performance at the highest wafer throughput, and will provide examples of the process performance achievable.« less

Concept and design of a beam blanker with integrated photoconductive switch for ultrafast electron microscopy.

PubMed

Weppelman, I G C; Moerland, R J; Hoogenboom, J P; Kruit, P

2018-01-01

We present a new method to create ultrashort electron pulses by integrating a photoconductive switch with an electrostatic deflector. This paper discusses the feasibility of such a system by analytical and numerical calculations. We argue that ultrafast electron pulses can be achieved for micrometer scale dimensions of the blanker, which are feasible with MEMS-based fabrication technology. According to basic models, the design presented in this paper is capable of generating 100 fs electron pulses with spatial resolutions of less than 10 nm. Our concept for an ultrafast beam blanker (UFB) may provide an attractive alternative to perform ultrafast electron microscopy, as it does not require modification of the microscope nor realignment between DC and pulsed mode of operation. Moreover, only low laser pulse energies are required. Due to its small dimensions the UFB can be inserted in the beam line of a commercial microscope via standard entry ports for blankers or variable apertures. The use of a photoconductive switch ensures minimal jitter between laser and electron pulses. Copyright © 2017 Elsevier B.V. All rights reserved.

Coupling of electrostatic ion cyclotron and ion acoustic waves in the solar wind

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

Sreeraj, T., E-mail: sreerajt13@iigs.iigm.res.in; Singh, S. V., E-mail: satyavir@iigs.iigm.res.in; Lakhina, G. S., E-mail: gslakhina@gmail.com

2016-08-15

The coupling of electrostatic ion cyclotron and ion acoustic waves is examined in three component magnetized plasma consisting of electrons, protons, and alpha particles. In the theoretical model relevant to solar wind plasma, electrons are assumed to be superthermal with kappa distribution and protons as well as alpha particles follow the fluid dynamical equations. A general linear dispersion relation is derived for such a plasma system which is analyzed both analytically and numerically. For parallel propagation, electrostatic ion cyclotron (proton and helium cyclotron) and ion acoustic (slow and fast) modes are decoupled. For oblique propagation, coupling between the cyclotron andmore » acoustic modes occurs. Furthermore, when the angle of propagation is increased, the separation between acoustic and cyclotron modes increases which is an indication of weaker coupling at large angle of propagation. For perpendicular propagation, only cyclotron modes are observed. The effect of various parameters such as number density and temperature of alpha particles and superthermality on dispersion characteristics is examined in details. The coupling between various modes occurs for small values of wavenumber.« less

Analysis of Flame Deflector Spray Nozzles in Rocket Engine Test Stands

NASA Technical Reports Server (NTRS)

Sachdev, Jai S.; Ahuja, Vineet; Hosangadi, Ashvin; Allgood, Daniel C.

2010-01-01

The development of a unified tightly coupled multi-phase computational framework is described for the analysis and design of cooling spray nozzle configurations on the flame deflector in rocket engine test stands. An Eulerian formulation is used to model the disperse phase and is coupled to the gas-phase equations through momentum and heat transfer as well as phase change. The phase change formulation is modeled according to a modified form of the Hertz-Knudsen equation. Various simple test cases are presented to verify the validity of the numerical framework. The ability of the methodology to accurately predict the temperature load on the flame deflector is demonstrated though application to an actual sub-scale test facility. The CFD simulation was able to reproduce the result of the test-firing, showing that the spray nozzle configuration provided insufficient amount of cooling.

Mechanically latchable tiltable platform for forming micromirrors and micromirror arrays

DOEpatents

Garcia, Ernest J [Albuquerque, NM; Polosky, Marc A [Tijeras, NM; Sleefe, Gerard E [Cedar Crest, NM

2006-12-12

A microelectromechanical (MEM) apparatus is disclosed which includes a platform that can be electrostatically tilted from being parallel to a substrate on which the platform to being tilted at an angle of 1 20 degrees with respect to the substrate. Once the platform has been tilted to a maximum angle of tilt, the platform can be locked in position using an electrostatically-operable latching mechanism which engages a tab protruding below the platform. The platform has a light-reflective upper surface which can be optionally coated to provide an enhanced reflectivity and form a micromirror. An array of such micromirrors can be formed on a common substrate for applications including optical switching (e.g. for fiber optic communications), optical information processing, image projection displays or non-volatile optical memories.

High-resolution (>5 800 time-bandwidth product) shear mode TeO2 deflector

NASA Astrophysics Data System (ADS)

Soos, Jolanta I.; Caviris, Nicholas P.; Phuvan, Sonlinh

1992-12-01

Acousto-optic deflectors play an important role in optical signal processing systems due to their real time processing capabilities, as well as their conversion capabilities of a function of time to a function of space and time. In this work Brimrose investigated the design and fabrication of state-of-the-art, very large time-bandwidth acousto-optic devices from TeO2 single crystals.

Permittivity changes induced by injected electrons and field-induced phase transition in KTa1-xNbxO3 optical beam deflectors

NASA Astrophysics Data System (ADS)

Imai, Tadayuki; Toyoda, Seiji; Miyazu, Jun; Kobayashi, Junya; Kojima, Seiji

2014-09-01

A space-charge-controlled optical beam deflector made of a KTa1-xNbxO3 (KTN) single crystal utilizes electrons that are injected through the cathode by applying voltage. With the deflector made of lithium-doped KTN (K0.95Li0.05Ta0.73Nb0.27O3, KLTN/0.05/0.27), we observed large increases in the capacitance of the deflector when we injected electrons. The increases were not caused by changes in the electrode interface but by changes in the permittivity of the bulk crystal. In the paraelectric phase, the KLTN/0.05/0.27 crystal exhibited nonlinearity in the dielectric response with double hysteresis loops in the D-E curves. We ascribed the permittivity change to this nonlinear phenomenon. We also discuss this nonlinearity in terms of the Landau-Devonshire phenomenological theory. The coefficient g4 of the fourth power term in the expanded free energy was negative in the paraelectric phase near the phase transition temperature as it is for other materials that exhibit a first-order phase transition. However, g4 depended on the temperature and its sign became positive about 15 °C above the phase transition temperature.

Dynamics of Quasi-Electrostatic Whistler waves in Earth's Radiation belts

NASA Astrophysics Data System (ADS)

Goyal, R.; Sharma, R. P.; Gupta, D. N.

2017-12-01

A numerical model is proposed to study the dynamics of high amplitude quasi-electrostatic whistler waves propagating near resonance cone angle and their interaction with finite frequency kinetic Alfvén waves (KAWs) in Earth's radiation belts. The quasi-electrostatic character of whistlers is narrated by dynamics of wave propagating near resonance cone. A high amplitude whistler wave packet is obtained using the present analysis which has also been observed by S/WAVES instrument onboard STEREO. The numerical simulation technique employed to study the dynamics, leads to localization (channelling) of waves as well as turbulent spectrum suggesting the transfer of wave energy over a range of frequencies. The turbulent spectrum also indicates the presence of quasi-electrostatic whistlers and density fluctuations associated with KAW in radiation belts plasma. The ponderomotive force of pump quasi-electrostatic whistlers (high frequency) is used to excite relatively much lower frequency waves (KAWs). The wave localization and steeper spectra could be responsible for particle energization or heating in radiation belts.

12. "TEST STAND; STRUCTURAL; DEFLECTOR PIT DETAILS, SHEET NO. 1." ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. "TEST STAND; STRUCTURAL; DEFLECTOR PIT DETAILS, SHEET NO. 1." Specifications No. ENG-04-353-55-72; Drawing No. 60-09-12; sheet 41 of 148; file no. 1320/92, Rev. A. Stamped: RECORD DRAWING - AS CONSTRUCTED. Below stamp: Contract no. 4338, no change. - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Test Stand 1-A Terminal Room, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Refractory Materials for Flame Deflector Protection System Corrosion Control: Flame Deflector Protection System Life Cycle Cost Analysis Report

NASA Technical Reports Server (NTRS)

Calle, Luz Marina; Hintze, Paul E.; Parlier, Christopher R.; Coffman, Brekke E.; Kolody, Mark R.; Curran, Jerome P.; Trejo, David; Reinschmidt, Ken; Kim, Hyung-Jin

2009-01-01

A 20-year life cycle cost analysis was performed to compare the operational life cycle cost, processing/turnaround timelines, and operations manpower inspection/repair/refurbishment requirements for corrosion protection of the Kennedy Space Center launch pad flame deflector associated with the existing cast-in-place materials and a newer advanced refractory ceramic material. The analysis compared the estimated costs of(1) continuing to use of the current refractory material without any changes; (2) completely reconstructing the flame trench using the current refractory material; and (3) completely reconstructing the flame trench with a new high-performance refractory material. Cost estimates were based on an analysis of the amount of damage that occurs after each launch and an estimate of the average repair cost. Alternative 3 was found to save $32M compared to alternative 1 and $17M compared to alternative 2 over a 20-year life cycle.

High-speed multi-frame dynamic transmission electron microscope image acquisition system with arbitrary timing

DOEpatents

Reed, Bryan W.; DeHope, William J.; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M.

2016-02-23

An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses each being of a programmable pulse duration, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has a plurality of plates. A control system having a digital sequencer controls the laser and a plurality of switching components, synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to enable programmable pulse durations and programmable inter-pulse spacings.

Ultra-fast framing camera tube

DOEpatents

Kalibjian, Ralph

1981-01-01

An electronic framing camera tube features focal plane image dissection and synchronized restoration of the dissected electron line images to form two-dimensional framed images. Ultra-fast framing is performed by first streaking a two-dimensional electron image across a narrow slit, thereby dissecting the two-dimensional electron image into sequential electron line images. The dissected electron line images are then restored into a framed image by a restorer deflector operated synchronously with the dissector deflector. The number of framed images on the tube's viewing screen is equal to the number of dissecting slits in the tube. The distinguishing features of this ultra-fast framing camera tube are the focal plane dissecting slits, and the synchronously-operated restorer deflector which restores the dissected electron line images into a two-dimensional framed image. The framing camera tube can produce image frames having high spatial resolution of optical events in the sub-100 picosecond range.

High-speed multiframe dynamic transmission electron microscope image acquisition system with arbitrary timing

DOEpatents

Reed, Bryan W.; DeHope, William J.; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M.

2015-10-20

An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses of a predefined pulse duration and waveform, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has two pairs of plates arranged perpendicular to one another. A control system controls the laser and a plurality of switching components synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to be provided with an independently set duration and independently set inter-pulse spacings.

High-speed multiframe dynamic transmission electron microscope image acquisition system with arbitrary timing

DOEpatents

Reed, Bryan W.; Dehope, William J; Huete, Glenn; LaGrange, Thomas B.; Shuttlesworth, Richard M

2016-06-21

An electron microscope is disclosed which has a laser-driven photocathode and an arbitrary waveform generator (AWG) laser system ("laser"). The laser produces a train of temporally-shaped laser pulses of a predefined pulse duration and waveform, and directs the laser pulses to the laser-driven photocathode to produce a train of electron pulses. An image sensor is used along with a deflector subsystem. The deflector subsystem is arranged downstream of the target but upstream of the image sensor, and has two pairs of plates arranged perpendicular to one another. A control system controls the laser and a plurality of switching components synchronized with the laser, to independently control excitation of each one of the deflector plates. This allows each electron pulse to be directed to a different portion of the image sensor, as well as to be provided with an independently set duration and independently set inter-pulse spacings.

Electrostatics effects in granular materials

NASA Astrophysics Data System (ADS)

Sarkar, Saurabh; Chaudhuri, Bodhisattwa

2013-06-01

This purpose of this study is to investigate the role of physiochemical properties and operational conditions in determining the electrostatic interactions between two species on a surface under typical industrial conditions. The variables considered for the study were particle type, particle size and shape, loading mass, surface type, angle of inclination of chute, nature and concentration of additive. Triboelectrification of simple and binary mixtures in a simple hopper and chute geometry was observed to be strongly linked to work function and moisture content of the powdered material.

Drag Reduction CFD Simulations and Flow Visualization of Light Vehicle-Trailer Systems

NASA Astrophysics Data System (ADS)

Sigurdson, Lorenz; Boyer, Henry; Lange, Carlos F.

2016-11-01

Experiments and CFD were performed to study the effect a deflector had on the flow and drag force associated with a 2010 F-150 truck and cargo trailer Light Vehicle-Trailer System (LVTS). Image Correlation Velocimetry (ICV) on smokewire streaklines measured the velocity field on the model mid-plane. CFD estimated the drag reduction as 13% at a Re of 14,900 with a moving ground-plane, and 17% without. Experiments suggested that the low Re does not diminish the full-scale relevance of the drag reduction results. One low Re effect was the presence of a separation bubble on the hood of the tow vehicle whose size reduced with an increase in Re. Three other characteristic flow patterns were identified: separation off the lead vehicle cab, stagnation of the free-stream on the trailer face for the no-deflector case, and subsequent separation at the trailer front corner. Comparisons of the ICV and CFD results with no deflector indicated good agreement in the direction of the velocity vectors, and the smoke streaklines and CFD streamlines also agreed well. However, for the deflector case, the CFD found an entirely different topological solution absent in the experiment. A pair of vertically-oriented mid-plane vortices were wrapped around the front of the trailer. Support from the Canadian Natural Sciences and Engineering Research Council Grant 41747 is gratefully acknowledged.

Tandem-Mirror Ion Source

NASA Technical Reports Server (NTRS)

Biddle, A.; Stone, N.; Reasoner, D.; Chisholm, W.; Reynolds, J.

1986-01-01

Improved ion source produces beam of ions at any kinetic energy from 1 to 1,000 eV, with little spread in energy or angle. Such ion beams useful in studies of surface properties of materials, surface etching, deposition, and development of plasma-diagnostic instrumentation. Tandemmirror ion source uses electrostatic and magnetic fields to keep electrons in ionization chamber and assure uniform output ion beam having low divergence in energy and angle.

Hydrodynamic characteristics of the oval cambered double slotted otter board in bottom trawl fisheries

NASA Astrophysics Data System (ADS)

Liu, J.; Huang, H. L.; Li, L. Z.; Qu, T. C.; Wu, Y.; Chen, S.; Yang, J. L.; Rao, X.

2017-07-01

The otter board is one of the main components of single boat trawl fisheries. An oval cambered double slotted otter board was developed for improving the expansion performance of trawl net in bottom trawl fisheries. A flume model experiment was conducted to measure the lift coefficient (C L), drag coefficient (C D), and lift to drag ratio (K) in different angles of attack (α). The experimental results are as follows : (1) The C L and K value show a trend of increasing at the beginning and then decreasing with the increase of angle of attack, the C D value reflects an upward trend as the angle of attack increases; (2) The D3 otter board (front flow deflector angle at 29°) showed a better hydrodynamic performance. When α=30°, the max lift coefficient (C Lmax) was 1.464, in this case C D = 0.554 and K=2.643. When α=15°, the max lift to drag ratio (K max) was 4.165, C L =0.633, and C D = 0.152. This suggests that the best working scope for the angle of attack is between 15°~30°, in which case, C L>0.633 and K>2.643. The mean value of the lift coefficient was 1.071 and the mean of the lift to drag ratio was 3.482. Comparative analysis of the hydrodynamic performance of different types of otter boards showed that the D3 otter board both had good expansion performance and efficiency, which can provide a reference basis for further optimization of the bottom trawl otter board.

Multiphase Modeling of Water Injection on Flame Deflector

NASA Technical Reports Server (NTRS)

Vu, Bruce T.; Bachchan, Nili; Peroomian, Oshin; Akdag, Vedat

2013-01-01

This paper describes the use of an Eulerian Dispersed Phase (EDP) model to simulate the water injected from the flame deflector and its interaction with supersonic rocket exhaust from a proposed Space Launch System (SLS) vehicle. The Eulerian formulation, as part of the multi-phase framework, is described. The simulations show that water cooling is only effective over the region under the liquid engines. Likewise, the water injection provides only minor effects over the surface area under the solid engines.

Use of an Acoustic Camera to Evaluate the Performance of Tickler Chains and Draghead Deflectors for Sea Turtle Protection during Hopper Dredging in the United States of America

DTIC Science & Technology

2018-05-01

performance nor effectiveness in protecting sea turtles has been documented.This study was the first step in evaluating TTC as a potential replacement for...draghead turtle deflectors. The primary objective was to evaluate and document operational performance of this technology, not effectiveness of reducing...incidental take. TTC operational performance was monitored using underwater camera systems over a short period of time whereas effectiveness for

Variable Entry Biased Paracentric Hemispherical Deflector: Experimental results on energy resolution for different entry positions

NASA Astrophysics Data System (ADS)

Dogan, Mevlut; Ulu, Melike; Gennerakis, Giannis; Zouros, Theo J. M.

2014-04-01

A new hemispherical deflector analyzer (HDA) which is designed for electron energy analysis in atomic collisions has been constructed and tested. Using the crossed beam technique at the electron spectrometer, test measurements were performed for electron beam (200 eV) - Helium atoms interactions. These first experimental results show that the paracentric entries give almost twice as good resolution as that for the conventional entry. Supporting simulations of the entire lens+HDA spectrometer are found in relatively good agreement with experiment.

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

Ploskey, Gene R.; Weiland, Mark A.; Faber, Derrek M.

This report describes a 2008 acoustic telemetry survival study conducted by the Pacific Northwest National Laboratory for the Portland District of the U.S. Army Corps of Engineers. The study estimated the survival of juvenile Chinook salmon and steelhead passing Bonneville Dam (BON) and its spillway. Of particular interest was the relative survival of smolts detected passing through end spill bays 1-3 and 16-18, which had deep flow deflectors immediately downstream of spill gates, versus survival of smolts passing middle spill bays 4-15, which had shallow flow deflectors.

Nonlinear Generation of Electromagnetic Waves through Induced Scattering by Thermal Plasma.

PubMed

Tejero, E M; Crabtree, C; Blackwell, D D; Amatucci, W E; Mithaiwala, M; Ganguli, G; Rudakov, L

2015-12-09

We demonstrate the conversion of electrostatic pump waves into electromagnetic waves through nonlinear induced scattering by thermal particles in a laboratory plasma. Electrostatic waves in the whistler branch are launched that propagate near the resonance cone. When the amplitude exceeds a threshold ~5 × 10(-6) times the background magnetic field, wave power is scattered below the pump frequency with wave normal angles (~59°), where the scattered wavelength reaches the limits of the plasma column. The scattered wave has a perpendicular wavelength that is an order of magnitude larger than the pump wave and longer than the electron skin depth. The amplitude threshold, scattered frequency spectrum, and scattered wave normal angles are in good agreement with theory. The results may affect the analysis and interpretation of space observations and lead to a comprehensive understanding of the nature of the Earth's plasma environment.

Design and application of multimegawatt X -band deflectors for femtosecond electron beam diagnostics

DOE PAGES

Dolgashev, Valery A.; Bowden, Gordon; Ding, Yuantao; ...

2014-10-02

Performance of the x-ray free electron laser Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET) is determined by the properties of their extremely short electron bunches. Multi-GeV electron bunches in both LCLS and FACET are less than 100 fs long. Optimization of beam properties and understanding of free-electron laser operation require electron beam diagnostics with time resolution of about 10 fs. We designed, built and commissioned a set of high frequency X-band deflectors which can measure the beam longitudinal space charge distribution and slice energy spread to better than 10 fs resolution at fullmore » LCLS energy (14 GeV), and with 70 fs resolution at full FACET energy (20 GeV). Use of high frequency and high gradient in these devices allows them to reach unprecedented performance. We report on the physics motivation, design considerations, operational configuration, cold tests, and typical results of the X-band deflector systems currently in use at SLAC.« less

Experimental Research on Optimizing Inlet Airflow of Wet Cooling Towers under Crosswind Conditions

NASA Astrophysics Data System (ADS)

Chen, You Liang; Shi, Yong Feng; Hao, Jian Gang; Chang, Hao; Sun, Feng Zhong

2018-01-01

A new approach of installing air deflectors around tower inlet circumferentially was proposed to optimize the inlet airflow and reduce the adverse effect of crosswinds on the thermal performance of natural draft wet cooling towers (NDWCT). And inlet airflow uniformity coefficient was defined to analyze the uniformity of circumferential inlet airflow quantitatively. Then the effect of air deflectors on the NDWCT performance was investigated experimentally. By contrast between inlet air flow rate and cooling efficiency, it has been found that crosswinds not only decrease the inlet air flow rate, but also reduce the uniformity of inlet airflow, which reduce NDWCT performance jointly. After installing air deflectors, the inlet air flow rate and uniformity coefficient increase, the uniformity of heat and mass transfer increases correspondingly, which improve the cooling performance. In addition, analysis on Lewis factor demonstrates that the inlet airflow optimization has more enhancement of heat transfer than mass transfer, but leads to more water evaporation loss.

Structural study of surfactant-dependent interaction with protein

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

Mehan, Sumit; Aswal, Vinod K., E-mail: vkaswal@barc.gov.in; Kohlbrecher, Joachim

2015-06-24

Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

Structural study of surfactant-dependent interaction with protein

NASA Astrophysics Data System (ADS)

Mehan, Sumit; Aswal, Vinod K.; Kohlbrecher, Joachim

2015-06-01

Small-angle neutron scattering (SANS) has been used to study the complex structure of anionic BSA protein with three different (cationic DTAB, anionic SDS and non-ionic C12E10) surfactants. These systems form very different surfactant-dependent complexes. We show that the structure of protein-surfactant complex is initiated by the site-specific electrostatic interaction between the components, followed by the hydrophobic interaction at high surfactant concentrations. It is also found that hydrophobic interaction is preferred over the electrostatic interaction in deciding the resultant structure of protein-surfactant complexes.

DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

NASA Astrophysics Data System (ADS)

Agnello, A.; Lin, H.; Kuropatkin, N.; Buckley-Geer, E.; Anguita, T.; Schechter, P. L.; Morishita, T.; Motta, V.; Rojas, K.; Treu, T.; Amara, A.; Auger, M. W.; Courbin, F.; Fassnacht, C. D.; Frieman, J.; More, A.; Marshall, P. J.; McMahon, R. G.; Meylan, G.; Suyu, S. H.; Glazebrook, K.; Morgan, N.; Nord, B.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Bechtol, K.; Benoit-Lévy, A.; Bertin, E.; Bernstein, R. A.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Carretero, J.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Drlica-Wagner, A.; Eifler, T. F.; Flaugher, B.; García-Bellido, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Gutierrez, J. Gschwend G.; Honscheid, K.; James, D. J.; Kuehn, K.; Lahav, O.; Lima, M.; Maia, M. A. G.; March, M.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Plazas, A. A.; Sanchez, E.; Scarpine, V.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Tucker, D.; Wechsler, R.

2018-06-01

We report the discovery, spectroscopic confirmation and first lens models of the first, strongly lensed quasars from a combined search in WISE and Gaia-DR1 over the DES footprint. Their Einstein radii span a range between ≈2.0″ and ≈0.4″. Two of these (WGD2038-4008, r.a.=20:38:02.65, dec.=-40:08:14.64; WGD2021-4115, r.a.=20:21:39.45, dec.=-41:15:57.11) also have confirmed deflector redshifts. The four-image lens WGD2038-4008, with source- and deflector- redshifts zs = 0.777 ± 0.001 and zl = 0.230 ± 0.002 respectively, has a deflector with radius Reff ≈ 3.4″, stellar mass log (M_{\\star }/M_{⊙})=11.64^{+0.20}_{-0.43}, and extended isophotal shape variation. Simple lens models yield Einstein radii RE = (1.30 ± 0.04)″, axis ratio q = 0.75 ± 0.1 (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lens WGD2021-4115has zs = 1.390 ± 0.001 and zl = 0.335 ± 0.002, and Einstein radius RE = (1.1 ± 0.1)″, but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. Analogous lens-model degeneracies hold for the other six lenses (J0146-1133, J0150-4041, J0235-2433, J0245-0556, J0259-2338, J0508-2748) shown in this paper.

Dust drift reduction effect of an air conveyor kit (dual-pipe deflector) mounted on different maize pneumatic drills.

PubMed

Manzone, Marco; Balsari, Paolo; Marucco, Paolo; Tamagnone, Mario

2017-03-01

All maize drills produce a fine dust due to the seed coating abrasions that occur inside the seeding element. The air stream generated by the fan of pneumatic drills - necessary to create a depression in the sowing element of the machine and to guarantee correct seed deposition - can blow away the solid particles detached from the seeds. In order to reduce this phenomenon, a coated maize seeds company (Syngenta®) has set up an ad hoc dual-pipe deflector kit that easily fits different pneumatic drills (also old drills). In this study, the efficiency of this kit and the influence of different drill types on the kit's performance in reducing environmental pollution were evaluated using three different pneumatic seed drill models. The research showed that a dual-pipe deflector installed on a drill in standard configuration did not change the seeder performance, and by using this kit on pneumatic drills, irrespective of their design, it is possible to reduce by up to 69% the amount of dust drift in comparison with the conventional machine set-up. The dual-pipe deflector, under the conditions employed in the present experiments, showed good performance with all types of maize pneumatic drill used. Irrespective of the seeder model on which it is mounted, it is able to obtain similar results, indicating its high operational versatility. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

The project of the mass separator of atomic nuclei produced in heavy ion induced reactions

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Shchepunov, V. A.; Dmitriev, S. N.; Itkis, M. G.; Gulbekyan, G. G.; Khabarov, M. V.; Bekhterev, V. V.; Bogomolov, S. L.; Efremov, A. A.; Pashenko, S. V.; Stepantsov, S. V.; Yeremin, A. V.; Yavor, M. I.; Kalimov, A. G.

2003-05-01

A new separator and mass analyzer, named MASHA (mass analyzer of super heavy atoms), has been designed at the Flerov Laboratory JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3. The set up can work in the wide mass range from A≈20 to A≈500, its mass acceptance is as large as ±2.8%. In particular, it allows unambiguous mass identification of super heavy nuclei with a resolution better than 1 amu at the level of 300 amu. Synthesized in nuclear reactions nuclides are emitted from an ECR ion source at energy E=40 kV and charge state Q=+1. Then they pass the following steps of separation and analysis: the first section of rough separation, the second section of separation and mass analysis and the final section of separation with a 90° electrostatic deflector. In the focal plane of the device, a focal plane detector determines positions (masses) of studied nuclei. Ion optics of the analyzer, optimized up to the second order, is considered. Description of its elements and subsystems is given.

Suppressing Ghost Diffraction in E-Beam-Written Gratings

NASA Technical Reports Server (NTRS)

Wilson, Daniel; Backlund, Johan

2009-01-01

A modified scheme for electron-beam (E-beam) writing used in the fabrication of convex or concave diffraction gratings makes it possible to suppress the ghost diffraction heretofore exhibited by such gratings. Ghost diffraction is a spurious component of diffraction caused by a spurious component of grating periodicity as described below. The ghost diffraction orders appear between the main diffraction orders and are typically more intense than is the diffuse scattering from the grating. At such high intensity, ghost diffraction is the dominant source of degradation of grating performance. The pattern of a convex or concave grating is established by electron-beam writing in a resist material coating a substrate that has the desired convex or concave shape. Unfortunately, as a result of the characteristics of electrostatic deflectors used to control the electron beam, it is possible to expose only a small field - typically between 0.5 and 1.0 mm wide - at a given fixed position of the electron gun relative to the substrate. To make a grating larger than the field size, it is necessary to move the substrate to make it possible to write fields centered at different positions, so that the larger area is synthesized by "stitching" the exposed fields.

High-Resolution Crystal Structures of Protein Helices Reconciled with Three-Centered Hydrogen Bonds and Multipole Electrostatics

PubMed Central

Kuster, Daniel J.; Liu, Chengyu; Fang, Zheng; Ponder, Jay W.; Marshall, Garland R.

2015-01-01

Theoretical and experimental evidence for non-linear hydrogen bonds in protein helices is ubiquitous. In particular, amide three-centered hydrogen bonds are common features of helices in high-resolution crystal structures of proteins. These high-resolution structures (1.0 to 1.5 Å nominal crystallographic resolution) position backbone atoms without significant bias from modeling constraints and identify Φ = -62°, ψ = -43 as the consensus backbone torsional angles of protein helices. These torsional angles preserve the atomic positions of α-β carbons of the classic Pauling α-helix while allowing the amide carbonyls to form bifurcated hydrogen bonds as first suggested by Némethy et al. in 1967. Molecular dynamics simulations of a capped 12-residue oligoalanine in water with AMOEBA (Atomic Multipole Optimized Energetics for Biomolecular Applications), a second-generation force field that includes multipole electrostatics and polarizability, reproduces the experimentally observed high-resolution helical conformation and correctly reorients the amide-bond carbonyls into bifurcated hydrogen bonds. This simple modification of backbone torsional angles reconciles experimental and theoretical views to provide a unified view of amide three-centered hydrogen bonds as crucial components of protein helices. The reason why they have been overlooked by structural biologists depends on the small crankshaft-like changes in orientation of the amide bond that allows maintenance of the overall helical parameters (helix pitch (p) and residues per turn (n)). The Pauling 3.613 α-helix fits the high-resolution experimental data with the minor exception of the amide-carbonyl electron density, but the previously associated backbone torsional angles (Φ, Ψ) needed slight modification to be reconciled with three-atom centered H-bonds and multipole electrostatics. Thus, a new standard helix, the 3.613/10-, Némethy- or N-helix, is proposed. Due to the use of constraints from monopole force fields and assumed secondary structures used in low-resolution refinement of electron density of proteins, such structures in the PDB often show linear hydrogen bonding. PMID:25894612

High-resolution crystal structures of protein helices reconciled with three-centered hydrogen bonds and multipole electrostatics.

PubMed

Kuster, Daniel J; Liu, Chengyu; Fang, Zheng; Ponder, Jay W; Marshall, Garland R

2015-01-01

Theoretical and experimental evidence for non-linear hydrogen bonds in protein helices is ubiquitous. In particular, amide three-centered hydrogen bonds are common features of helices in high-resolution crystal structures of proteins. These high-resolution structures (1.0 to 1.5 Å nominal crystallographic resolution) position backbone atoms without significant bias from modeling constraints and identify Φ = -62°, ψ = -43 as the consensus backbone torsional angles of protein helices. These torsional angles preserve the atomic positions of α-β carbons of the classic Pauling α-helix while allowing the amide carbonyls to form bifurcated hydrogen bonds as first suggested by Némethy et al. in 1967. Molecular dynamics simulations of a capped 12-residue oligoalanine in water with AMOEBA (Atomic Multipole Optimized Energetics for Biomolecular Applications), a second-generation force field that includes multipole electrostatics and polarizability, reproduces the experimentally observed high-resolution helical conformation and correctly reorients the amide-bond carbonyls into bifurcated hydrogen bonds. This simple modification of backbone torsional angles reconciles experimental and theoretical views to provide a unified view of amide three-centered hydrogen bonds as crucial components of protein helices. The reason why they have been overlooked by structural biologists depends on the small crankshaft-like changes in orientation of the amide bond that allows maintenance of the overall helical parameters (helix pitch (p) and residues per turn (n)). The Pauling 3.6(13) α-helix fits the high-resolution experimental data with the minor exception of the amide-carbonyl electron density, but the previously associated backbone torsional angles (Φ, Ψ) needed slight modification to be reconciled with three-atom centered H-bonds and multipole electrostatics. Thus, a new standard helix, the 3.6(13/10)-, Némethy- or N-helix, is proposed. Due to the use of constraints from monopole force fields and assumed secondary structures used in low-resolution refinement of electron density of proteins, such structures in the PDB often show linear hydrogen bonding.

Electrostatic 2D assembly of bionanoparticles on a cationic lipid monolayer.

NASA Astrophysics Data System (ADS)

Kewalramani, Sumit; Wang, Suntao; Fukuto, Masafumi; Yang, Lin; Niu, Zhongwei; Nguyen, Giang; Wang, Qian

2010-03-01

We present a grazing-incidence small-angle X-ray scattering (GISAXS) study on 2D assembly of cowpea mosaic virus (CPMV) under a mixed cationic-zwitterionic (DMTAP^+-DMPC) lipid monolayer at the air-water interface. The inter-particle and particle-lipid electrostatic interactions were varied by controlling the subphase pH and the membrane charge density. GISAXS data show that 2D crystals of CPMV are formed above a threshold membrane charge density and only in a narrow pH range just above CPMV's isoelectric point, where the charge on CPMV is expected to be weakly negative. The particle density for the 2D crystals is similar to that for the densest lattice plane in the 3D crystals of CPMV. The results show that the 2D crystallization is achieved in the part of the phase space where the electrostatic interactions are expected to maximize the adsorption of CPMV onto the lipid membrane. This electrostatics-based strategy for controlling interfacial nanoscale assembly should be generally applicable to other nanoparticles.

Electrostatic turbulence in the earth's central plasma sheet produced by multiple-ring ion distributions

NASA Technical Reports Server (NTRS)

Huba, J. D.; Chen, J.; Anderson, R. R.

1992-01-01

Attention is given to a mechanism to generate a broad spectrum of electrostatic turbulence in the quiet time central plasma sheet (CPS) plasma. It is shown theoretically that multiple-ring ion distributions can generate short-wavelength (less than about 1), electrostatic turbulence with frequencies less than about kVj, where Vj is the velocity of the jth ring. On the basis of a set of parameters from measurements made in the CPS, it is found that electrostatic turbulence can be generated with wavenumbers in the range of 0.02 and 1.0, with real frequencies in the range of 0 and 10, and with linear growth rates greater than 0.01 over a broad range of angles relative to the magnetic field (5-90 deg). These theoretical results are compared with wave data from ISEE 1 using an ion distribution function exhibiting multiple-ring structures observed at the same time. The theoretical results in the linear regime are found to be consistent with the wave data.

Dependence of field-aligned electron precipitation on season, altitude and pitch angle

NASA Technical Reports Server (NTRS)

Berko, F. W.; Hoffman, R. A.

1973-01-01

The occurrence of field-aligned 2.3 keV electron precipitation was examined by using data from more than 7500 orbits of the polar-orbiting satellite, OGO-4. The frequency of occurrence of field aligned precipitation was highest at actual pitch angles between 7 and 10 deg, being highest in the winter months, at highest satellite altitudes. Acceleration by a localized parallel electric field established by electrostatic charge layers is proposed to explain particle observations.

Electrostatic Solitary Waves in the Solar Wind: Evidence for Instability at Solar Wind Current Sheets

NASA Technical Reports Server (NTRS)

Malaspina, David M.; Newman, David L.; Wilson, Lynn Bruce; Goetz, Keith; Kellogg, Paul J.; Kerstin, Kris

2013-01-01

A strong spatial association between bipolar electrostatic solitary waves (ESWs) and magnetic current sheets (CSs) in the solar wind is reported here for the first time. This association requires that the plasma instabilities (e.g., Buneman, electron two stream) which generate ESWs are preferentially localized to solar wind CSs. Distributions of CS properties (including shear angle, thickness, solar wind speed, and vector magnetic field change) are examined for differences between CSs associated with ESWs and randomly chosen CSs. Possible mechanisms for producing ESW-generating instabilities at solar wind CSs are considered, including magnetic reconnection.

Role of electrostatic interaction on surfactant induced protein unfolding

NASA Astrophysics Data System (ADS)

Sumit, Kumar, Sugam; Aswal, V. K.

2013-02-01

Small Angle Neutron Scattering has been used to examine the effect of electrostatic interaction on surfactant induced protein unfolding. Measurements are carried out from 1 wt% Bovine Serum Albumin (BSA) protein with 1 wt% Sodium Dodecyl Sulphate (SDS) surfactant at pH 7 in presence of varying concentration of NaCl. It is found that both the components (protein and surfactant micelle which are likely charged) exist individually without any interaction in absence of salt, whereas their interaction and protein unfolding is enhanced with the increase in salt concentration. The structure of protein-surfactant interaction is characterized by fractal bead-necklace model.

Influence of gas flow and applied voltage on interaction of jets in a cross-field helium plasma jet array

NASA Astrophysics Data System (ADS)

Wan, Meng; Liu, Feng; Fang, Zhi; Zhang, Bo; Wan, Hui

2017-09-01

Atmospheric Pressure Plasma Jet arrays can greatly enhance the treatment area to fulfill the need for large-scale surface processing, while the spatial uniformity of the plasma jet array is closely related to the interactions of the adjacent jets. In this paper, a three-tube one-dimensional (1D) He plasma jet array with a cross-field needle-ring electrode structure is used to investigate the influences of the gas flow rate and applied voltage on the interactions of the adjacent jets through electrical, optical, and fluid measurements. The repulsion of the adjacent plume channels is observed using an intensified charge-coupled device (ICCD) and the influence of the gas flow rate and applied voltage on the electrostatic repulsion force, Coulomb force, is discussed. It is found that electrical coupling, mainly electrostatic repulsion force, exists among the jets in the array, which causes both the divergence of the lateral plumes and the nonlinear changes of the discharge power and the transport charge. The deflection angle of the lateral plumes with respect to the central plume in the optical images increases with the increase of applied voltage and decreases with the increase of gas flow rate. The deflection angle of the lateral plumes in the optical images is obviously larger than that of the lateral gas streams in the Schlieren images under the same experimental conditions, and the unconformity of the deflection angles is mainly attributed to the electrostatic repulsion force in adjacent plasma plume channels. The experimental results can help understand the interaction mechanisms of jets in the array and design controllable and scalable plasma jet arrays.

Testing of lift/cruise fan exhaust deflector. [for a tip turbine lift fan in short takeoff aircraft

NASA Technical Reports Server (NTRS)

Schlundt, D. W.

1975-01-01

A lift/cruise exhaust deflector system for the LF336/A tip turbine lift fan was designed, built, and tested to determine the design and performance characteristics of a large-scale, single swivel nozzle thrust vectoring system. The exhaust deflector static testing was performed at the Ames Research Center outside static test stand facilities. The test hardware was installed on a hydraulic lift platform to permit both in and out of ground effect testing. The exhaust flow of the LF336/A lift fan was vectored from 0 degrees through 130 degrees during selected fan speeds to obtain performance at different operating conditions. The system was operated with and without flow vanes installed in the small radius bends to evaluate the system performance based on a proposed method of improving the internal flow losses. The program also included testing at different ground heights, to the nozzle exhaust plane, to obtain ground effect data, and the testing of two methods of thrust spoiling using a duct bypass door system and nozzle flap system.

Progress in developing Poisson-Boltzmann equation solvers

PubMed Central

Li, Chuan; Li, Lin; Petukh, Marharyta; Alexov, Emil

2013-01-01

This review outlines the recent progress made in developing more accurate and efficient solutions to model electrostatics in systems comprised of bio-macromolecules and nano-objects, the last one referring to objects that do not have biological function themselves but nowadays are frequently used in biophysical and medical approaches in conjunction with bio-macromolecules. The problem of modeling macromolecular electrostatics is reviewed from two different angles: as a mathematical task provided the specific definition of the system to be modeled and as a physical problem aiming to better capture the phenomena occurring in the real experiments. In addition, specific attention is paid to methods to extend the capabilities of the existing solvers to model large systems toward applications of calculations of the electrostatic potential and energies in molecular motors, mitochondria complex, photosynthetic machinery and systems involving large nano-objects. PMID:24199185

Post STS-135 Evaluation of Main Flame Deflector Witness Materials

NASA Technical Reports Server (NTRS)

Long, Victoria

2011-01-01

NASA and USA design engineers submitted witness materials from the solid rocket booster (SRB) main flame deflector for evaluation after the launch of STS-135. The following items were submitted for analysis: HY-80 steel witnes rods, 304 sta inles steel caps, and tungsten pistons. All of the items were photographed in order to document their condition after the launch of STS-135. The submitted samples were dimensionally measured in order to determine the amount of material lost during launch. Microstructural changes were observed in the HY-80 witness rod metallographic samples due to the heat of the launch.

Post STS-134 Evaluation of Main Flame Deflector Witness Materials

NASA Technical Reports Server (NTRS)

Long, Victoria

2011-01-01

NASA and USA design engineers submitted witness materials from the solid rocket booster (SRB) main flame deflector for evaluation after the launch of STS-134. The following items were submitted for analysis: 1018 steel witness rods 304 stainless steel caps, tungsten pistons, and A-286 piston sleeves. All of the items were photographed in order to document their condition after the launch of STS-134. All of the items were dimensionally measured in order to determine the amount of material lost during launch. Microstructural changes were observed in the 1018 witness rod metallographic samples due to the heat of the launch

Conserved electrostatic fields at the Ras-effector interface measured through vibrational Stark effect spectroscopy explain the difference in tilt angle in the Ras binding domains of Raf and RalGDS.

PubMed

Walker, David M; Wang, Ruifei; Webb, Lauren J

2014-10-07

Vibrational Stark effect (VSE) spectroscopy was used to measure the electrostatic fields present at the interface of the human guanosine triphosphatase (GTPase) Ras docked with the Ras binding domain (RBD) of the protein kinase Raf. Nine amino acids located on the surface of Raf were selected for labeling with a nitrile vibrational probe. Eight of the probe locations were situated along the interface of Ras and Raf, and one probe was 2 nm away on the opposite side of Raf. Vibrational frequencies of the nine Raf nitrile probes were compared both in the monomeric, solvated protein and when docked with wild-type (WT) Ras to construct a comprehensive VSE map of the Ras-Raf interface. Molecular dynamics (MD) simulations employing an umbrella sampling strategy were used to generate a Boltzmann-weighted ensemble of nitrile positions in both the monomeric and docked complexes to determine the effect that docking has on probe location and orientation and to aid in the interpretation of VSE results. These results were compared to an identical study that was previously conducted on nine nitrile probes on the RBD of Ral guanidine dissociation stimulator (RalGDS) to make comparisons between the docked complexes formed when either of the two effectors bind to WT Ras. This comparison finds that there are three regions of conserved electrostatic fields that are formed upon docking of WT Ras with both downstream effectors. Conservation of this pattern in the docked complex then results in different binding orientations observed in otherwise structurally similar proteins. This work supports an electrostatic cause of the known binding tilt angle between the Ras-Raf and Ras-RalGDS complexes.

Surface charge-induced EDL interaction on the contact angle of surface nanobubbles.

PubMed

Jing, Dalei; Li, Dayong; Pan, Yunlu; Bhushan, Bharat

2016-11-01

The contact angle (CA) of surface nanobubbles is believed to affect the stability of nanobubbles and fluid drag in micro/nanofluidic systems. The CA of nanobubbles is dependent on size and is believed to be affected by the surface charge-induced electrical double layer (EDL). However, neither of these of attributes are well understood. In this paper, by introducing an EDL-induced electrostatic wetting tension, a theoretical model is first established to study the effect of EDLs formed near the solid-liquid interface and the liquid-nanobubble interface on the gas phase CA of nanobubbles. The size-dependence of this EDL interaction is studied as well. Next, by using atomic force microscopy (AFM), the effect of the EDL on nanobubbles' gas phase CA is studied with variable electrical potential at the solid-liquid interface, which is adjusted by an applied voltage. Both the theoretical and the experimental results show that the EDLs formed near the solid-liquid interface and the liquid-nanobubble interface lead to a reduction of gas phase CA of the surface nanobubbles because of an electrostatic wetting tension on the nanobubble due to the attractive electrostatic interaction between the liquid and nanobubble within the EDL, which is in the nanobubbles' outward direction. An EDL with a larger zeta potential magnitude leads to a larger gas phase CA reduction. Furthermore, the effect of EDL on the nanobubbles' gas phase CA shows a significant size-dependence considering the size dependence of the electrostatic wetting tension. The gas phase CA reduction due to the EDL decreases with increasing nanobubble height and increases with the nanobubble's increasing curvature radius, indicating that a surface charge-induced EDL could possibly explain the size dependence of the gas phase CA of nanobubbles.

Probing Na+ Induced Changes in the HIV-1 TAR Conformational Dynamics using NMR Residual Dipolar Couplings: New Insights into the Role of Counterions and Electrostatic Interactions in Adaptive Recognition†

PubMed Central

Casiano-Negroni, Anette; Sun, Xiaoyan; Al-Hashimi, Hashim M.

2012-01-01

Many regulatory RNAs undergo large changes in structure upon recognition of proteins and ligands but the mechanism by which this occur remains poorly understood. Using NMR residual dipolar coupling (RDCs), we characterized Na+ induced changes in the structure and dynamics of the bulge-containing HIV-1 transactivation response element (TAR) RNA that mirror changes induced by small molecules bearing a different number of cationic groups. Increasing the Na+ concentration from 25 mM to 320 mM led to a continuous reduction in the average inter-helical bend angle (from 46° to 22°), inter-helical twist angle (from 66° to −18°) and inter-helix flexibility (as measured by an increase in the internal generalized degree of order from 0.56 to 0.74). Similar conformational changes were observed with Mg2+, indicating that non-specific electrostatic interactions drive the conformational transition, although results also suggest that Na+ and Mg2+ may associate with TAR in distinct modes. The transition can be rationalized based on a population-weighted average of two ensembles comprising an electrostatically relaxed bent and flexible TAR conformation that is weakly associated with counterions, and a globally rigid coaxial conformation which has stronger electrostatic potential and association with counterions. The TAR inter-helical orientations that are stabilized by small molecules fall around the metal-induced conformational pathway, indicating that counterions may help predispose the TAR conformation for target recognition. Our results underscore the intricate sensitivity of RNA conformational dynamics to environmental conditions and demonstrate the ability to detect subtle conformational changes using NMR RDCs. PMID:17488097

Sensor Fish Characterization of Fish Passage Conditions through John Day Dam Spillbay 20 with a Modified Flow Deflector

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

Duncan, Joanne P.

Fish passage conditions over a modified deflector in Spillbay 20 at John Day Dam were evaluated by Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers (USACE), Portland District, using Sensor Fish devices. The objectives of the study were to describe and compare passage exposure conditions at two spill discharges, 2.4 and 4.0 thousand cubic feet per second (kcfs), identifying potential fish injury regions within the routes, and to evaluate a low-tailwater condition at the 2.4-kcfs discharge. The study was performed in April 2010 concurrent with HI-Z balloon-tag studies by Normandeau Associates, Inc. Sensor Fish data were analyzedmore » to estimate 1) exposure conditions, particularly exposure to severe collision and shear events; 2) differences in passage conditions between treatments; and 3) relationships to live-fish injury and mortality data estimates. Nearly all Sensor Fish significant events were classified as collisions; the most severe occurred at the gate, on the spillbay chute, or at the deflector transition. Collisions in the gate region were observed only during the 2.4-kcfs discharge, when the tainter gate was open 1.2 ft. One shear event was observed during the evaluation, occurring at the deflector transition during passage at the 2.4-kcfs discharge at low tailwater. Flow quality, computed using the Sensor Fish turbulence index, was best for passage at the low-flow low-tailwater condition as well. The worst flow quality was observed for the 4.0-kcfs test condition. Contrasting the passage exposure conditions, the 2.4-kcfs low-tailwater treatment would be most deleterious to fish survival and well-being.« less

Measuring the total and baryonic mass profiles of the very massive CASSOWARY 31 strong lens. A fossil system at z ≃ 0.7?

NASA Astrophysics Data System (ADS)

Grillo, C.; Christensen, L.; Gallazzi, A.; Rasmussen, J.

2013-08-01

We investigate the total and baryonic mass distributions in deflector number 31 (CSWA 31) of the Cambridge And Sloan Survey Of Wide ARcs in the skY (CASSOWARY). We confirm spectroscopically a four-image lensing system at redshift 1.4870 with Very Large Telescope/X-shooter observations. The lensed images are distributed around a bright early-type galaxy at redshift 0.683, surrounded by several smaller galaxies at similar photometric redshifts. We use available optical and X-ray data to constrain the deflector total, stellar and hot gas mass through, respectively, strong lensing, stellar population analysis and plasma modelling. We derive a total mass projected within the Einstein radius REin = 70 kpc of (40 ± 1) × 1012 M⊙, and a central logarithmic slope of -1.7 ± 0.2 for the total mass density. Despite a very high stellar mass and velocity dispersion of the central galaxy of (3 ± 1) × 1012 M⊙ and (450 ± 80) km s-1, respectively, the cumulative stellar-to-total mass profile of the deflector implies a remarkably low stellar mass fraction of 20 per cent (3-6 per cent) in projection within the central galaxy effective radius Re = 25 kpc (R = 100 kpc). We also find that the CSWA 31 deflector has properties suggesting it to be among the most distant and massive fossil systems studied so far. The unusually strong central dark matter dominance and the possible fossil nature of this system render it an interesting target for detailed tests of cosmological models and structure formation scenarios.

Ab initio study of the electrostatic multipole nature of torsional potentials in CH3SSCH3, CH3SSH, and HOOH

NASA Technical Reports Server (NTRS)

Sokalski, W. A.; Lai, J.; Luo, N.; Sun, S.; Shibata, M.; Ornstein, R.; Rein, R.

1991-01-01

The origin of torsional potentials in H3CSSCH3, H3CSSH, and HOOH and the anisotropy of the local charge distribution has been analyzed in terms of atomic multipoles calculated from the ab initio LCAO-MO-SCF wave function in the 6-31G* basis set. The results indicate that for longer -S-S-bonds the major contribution to these torsional barriers are electrostatic interactions of the atomic multipoles located on two atoms forming the rotated bond. This finding demonstrates the important role of electrostatic 1-2 interatomic interactions, usually neglected in conformational studies. It also opens the possibility to derive directly from accurate ab initio wave functions a simple nonempirical torsional potential involving atomic multipoles of two bonded atoms defining the torsional angle. For shorter -O-O- bonds, use of more precise models and inclusion of 1-3 interactions seems to be necessary.

A rocket-borne electrostatic analyzer for measurement of energetic particle flux

NASA Technical Reports Server (NTRS)

Pozzi, M. A.; Smith, L. G.; Voss, H. D.

1979-01-01

A rocket-borne electrostatic analyzer experiment is described. It is used to measure energetic particle flux (0.9 to 14 keV) in the nighttime midlatitude E region. Energetic particle precipitation is believed to be a significant nighttime ionization source, particularly during times of high geomagnetic activity. The experiment was designed for use in the payload of a Nike Apache sounding rocket. The electrostatic analyzer employs two cylindrical parallel plates subtending a central angle of 90 deg. The voltage waveform supplied to the plates is a series of steps synchronized to the spin of the payload during flight. Both positive and negative voltages are provided, extending the detection capabilities of the instrument to both electrons and protons (and positive ions). The development, construction and operation of the instrument is described together with a preliminary evaluation of its performance in a rocket flight.

Solar wind pickup of ionized Venus exosphere atoms

NASA Technical Reports Server (NTRS)

Curtis, S. A.

1981-01-01

Previous calculations of electrostatic and electromagnetic growth rates for plasma instabilities have neglected the thermal spread of the distribution function of the planetary ions. We consider the effects of finite temperatures for exospheric ions borne in the solar wind. Specifically, growth rates are calculated for electromagnetic instabilities in the low-frequency case for Alfven waves and the intermediate frequency case for whistlers. Also, electrostatic growth rates are calculated for the intermediate frequency regime. From these growth rates, estimates are derived for the pickup times of the planetary ions. The electromagnetic instabilities are shown to produce the most rapid pickup. In the situation where the angle between the local Venus magnetic field and the plasma flow direction is small, the pickup times for both electromagnetic and electrostatic instabilities become very long. A possible consequence of this effect is to produce regions of enhanced planetary ion density in favorable Venus magnetic field-solar wind flow geometries.

Encapsulated high frequency (235 kHz), high-Q (100 k) disk resonator gyroscope with electrostatic parametric pump

NASA Astrophysics Data System (ADS)

Ahn, C. H.; Nitzan, S.; Ng, E. J.; Hong, V. A.; Yang, Y.; Kimbrell, T.; Horsley, D. A.; Kenny, T. W.

2014-12-01

In this paper, we explore the effects of electrostatic parametric amplification on a high quality factor (Q > 100 000) encapsulated disk resonator gyroscope (DRG), fabricated in <100> silicon. The DRG was operated in the n = 2 degenerate wineglass mode at 235 kHz, and electrostatically tuned so that the frequency split between the two degenerate modes was less than 100 mHz. A parametric pump at twice the resonant frequency is applied to the sense axis of the DRG, resulting in a maximum scale factor of 156.6 μV/(°/s), an 8.8× improvement over the non-amplified performance. When operated with a parametric gain of 5.4, a minimum angle random walk of 0.034°/√h and bias instability of 1.15°/h are achieved, representing an improvement by a factor of 4.3× and 1.5×, respectively.

A theoretical and experimental investigation of cylindrical electrostatic probes at arbitrary incidence in flowing plasma

NASA Technical Reports Server (NTRS)

Jenkins, R. V.; Jones, W. L., Jr.

1974-01-01

The theory for calculating the current collected by a negatively biased cylindrical electrostatic probe at an arbitrary angle of attack in a weakley ionized flowing plasma is presented. The theory was constructed by considering both random and directed motion simultaneous with dynamic coupling of the flow properties and of the electric field of the probe. This direct approach yielded a theory that is more general than static plasma theories modified to account for flow. Theoretical calculations are compared with experimental electrostatic probe data obtained in the free stream of an arc-heated hypersonic wind tunnel. The theoretical calculations are based on flow conditions and plasma electron densities measured by an independent microwave interferometer technique. In addition, the theory is compared with laboratory and satellite data previously published by other investigators. In each case the comparison gives good agreement.

The 80 kV electrostatic wire septum for AmPS

NASA Astrophysics Data System (ADS)

Vanderlinden, A.; Bijleveld, J. H. M.; Rookhuizen, H. Boer; Bruinsma, P. J. T.; Heine, E.; Lassing, P.; Prins, E.

The characteristics of the wire septum for the Amsterdam Pulse Stretcher (AmPS) are summarized. In the extraction process of the AmPS the extracted beam is intercepted from the circulating beam by the 1 m long electrostatic wire septum. For a bending angle of 4.4 mrad, the maximum anode voltage is 80 kV. The system developed consists of a wire spacing of 0.65 mm between tungsten wires of 50 micrometers diameter. Stainless steel spring wires, bent in a half cylindrical carrier, stretch the septum wires two by two. Prototype tests were successful up to an anode voltage of 120 kV.

Effect of polarization on the stability of a helix dimer

NASA Astrophysics Data System (ADS)

Wang, Xing Y.; Zhang, John Z. H.

2011-01-01

Molecular dynamics (MD) simulations have been carried out to study helix-helix interaction using both standard AMBER and polarized force fields. Comparison of the two simulations shows that electrostatic polarization of intra-protein hydrogen bonds plays a significant role in stabilizing the structure of helix dimer. This stabilizing effect is clearly demonstrated by examining the monomer structure, helix crossing angle and stability of backbone hydrogen bonds under AMBER and PPC. Since reliable prediction of protein-protein structure is a significant challenge, the current study should help shed light on the importance of electrostatic polarization of protein in helix-helix interaction and helix bundle structures.

Nonlinear low-frequency electrostatic wave dynamics in a two-dimensional quantum plasma

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

Ghosh, Samiran, E-mail: sran_g@yahoo.com; Chakrabarti, Nikhil, E-mail: nikhil.chakrabarti@saha.ac.in

2016-08-15

The problem of two-dimensional arbitrary amplitude low-frequency electrostatic oscillation in a quasi-neutral quantum plasma is solved exactly by elementary means. In such quantum plasmas we have treated electrons quantum mechanically and ions classically. The exact analytical solution of the nonlinear system exhibits the formation of dark and black solitons. Numerical simulation also predicts the possible periodic solution of the nonlinear system. Nonlinear analysis reveals that the system does have a bifurcation at a critical Mach number that depends on the angle of propagation of the wave. The small-amplitude limit leads to the formation of weakly nonlinear Kadomstev–Petviashvili solitons.

Transport in a magnetic field modulated graphene superlattice.

PubMed

Li, Yu-Xian

2010-01-13

Using the transfer matrix method, we study the transport properties through a magnetic field modulated graphene superlattice. It is found that the electrostatic barrier, the magnetic vector potential, and the number of wells in a superlattice modify the transmission remarkably. The angular dependent transmission is blocked by the magnetic vector potential because of the appearance of the evanescent states at certain incident angles, and the region of Klein tunneling shifts to the left. The angularly averaged conductivities exhibit oscillatory behavior. The magnitude and period of oscillation depend sensitively on the height of the electrostatic barrier, the number of wells, and the strength of the modulated magnetic field.

Application of Glow Discharge Plasma to Alter Surface Properties of Materials

NASA Technical Reports Server (NTRS)

Trigwell, Steve; Buhler, Charles R.; Calle, Carlos I.

2005-01-01

Some polymer materials that are considered important for spaceport operations are rendered noncompliant when subjected to the Kennedy Space Center (KSC) Standard electrostatic testing. These materials operate in stringent environmental conditions, such as high humidity. Treating materials that fail electrostatic testing and altering their surface properties so that they become compliant would result in considerable cost savings. Significant improvement in electrostatic dissipation of Saf-T-Vu PVC after treatment with air Atmospheric Plasma Glow Discharge (APGD) was observed and the material now passed the KSC electrostatic test. The O:C ratio on the surface, as monitored by X-ray Photoelectron Spectroscopy, increased from 0.165 tO 0.275 indicating enhanced oxidation, and surface contact angle measurements decreased from 107.5 to 72.6 showing increased hydrophilicity that accounted for the increased conductivity. Monitoring of the aging showed that the materials hydrophobic recovery resulted in it failing the electrostatic test 30 hours after treatment. This was probably due to the out-diffusion of the added Zn, Ba, and Cd salt stabilizers detected on the surface and/or diffusion of low molecular weight oligomers. On going work includes improving the long term hydrophilicity by optimizing the APGD process with different gas mixtures. Treatment of other spaceport materials is also presented.

Temperature Controlled Electrostatic Disorder and Polymorphism in Ultrathin Films of α-Sexithiophene

NASA Astrophysics Data System (ADS)

Hoffman, Benjamin; Jafari, Sara; McAfee, Terry; Apperson, Aubrey; O'Connor, Brendan; Dougherty, Daniel

Competing phases in well-ordered alpha-sexithiophene (α-6T) are shown to contribute to electrostatic disorder observed by differences in surface potential between mono- and bi-layer crystallites. Ultrathin films are of key importance to devices in which charge transport occurs in the first several monolayers nearest to a dielectric interface (e.g. thin film transistors) and complex structures in this regime impact the general electrostatic landscape. This study is comprised of 1.5 ML sample crystals grown via organic molecular beam deposition onto a temperature controlled hexamethyldisilazane (HMDS) passivated SiO2 substrate to produce well-ordered layer-by-layer type growth. Sample topography and surface potential were characterized simultaneously using Kelvin Probe Force Microscopy to then isolate contact potential differences by first and second layer α-6T regions. Films grown on 70° C, 120° C substrates are observed to have a bilayer with lower, higher potential than the monolayer, respectively. Resulting interlayer potential differences are a clear source of electrostatic disorder and are explained as subtle shifts in tilt-angles between layers relative to the substrate. These empirical results continue our understanding of how co-existing orientations contribute to the complex electrostatics influencing charge transport. NSF CAREER award DMR-1056861.

Status of the "new" AMS facility in Trondheim

NASA Astrophysics Data System (ADS)

Nadeau, Marie-Josée; Vaernes, Einar; Svarva, Helene Løvstrand; Larsen, Eiliv; Gulliksen, Steinar; Klein, Matthias; Mous, Dirk J. W.

2015-10-01

The Radiocarbon Laboratory of the Norwegian University of Science and Technology (NTNU) in Trondheim has a long history, dating back to the 1950s. Its relatively new AMS facility is based on a 1 MV Tandetron from High Voltage Engineering Europa B.V. that is equipped with a hybrid solid/gas SO-110 ion source, a low energy spectrometer supporting sequential injection, a high energy analysis system consisting of a magnet and an electrostatic deflector, allowing insertion of an absorber foil for isobar suppression, and a two dimensional gas ionisation detector (E and ΔE). The system is at present capable of measuring 10Be, 14C, and 26Al and can be easily modified to measure isotopes of higher masses. Acceptance tests results for 10Be1+, 14C2+, 26Al1+, and 26Al3+ are presented. The laboratory measures only 14C at present and the routine procedures are described. The system has demonstrated a very low background (70,000 14C years BP or 2·10-16 on Alfa Aesar 40795 graphite powder, -200 mesh, 99.9995%) for 14C when charge state 2+ is measured and the interference of Li ions in the detector is minimal. Some ion optical peculiarities of the system are also discussed.

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

Summers, D. J.; Hart, T. L.; Acosta, J. G.

We propose a novel scheme for final muon ionization cooling with quadrupole doublets followed by emittance exchange in vacuum to achieve the small beam sizes needed by a muon collider. A flat muon beam with a series of quadrupole doublet half cells appears to provide the strong focusing required for final cooling. Each quadrupole doublet has a low beta region occupied by a dense, low Z absorber. After final cooling, normalized transverse, longitudinal, and angular momentum emittances of 0.100, 2.5, and 0.200 mm-rad are exchanged into 0.025, 70, and 0.0 mm-rad. A skew quadrupole triplet transforms a round muon bunchmore » with modest angular momentum into a flat bunch with no angular momentum. Thin electrostatic septa efficiently slice the flat bunch into 17 parts. The 17 bunches are interleaved into a 3.7 meter long train with RF deflector cavities. Snap bunch coalescence combines the muon bunch train longitudinally in a 21 GeV ring in 55 µs, one quarter of a synchrotron oscillation period. A linear long wavelength RF bucket gives each bunch a different energy causing the bunches to drift in the ring until they merge into one bunch and can be captured in a short wavelength RF bucket with a 13% muon decay loss and a packing fraction as high as 87 %.« less

Evaluation of Alternative Refractory Materials for the Main Flame Deflectors at KSC Launch Complexes

NASA Technical Reports Server (NTRS)

Calle, Luz Marina; Trejo, David; Rutkowsky, Justin

2006-01-01

The deterioration of the refractory materials used to protect the KSC launch complex steel base structures from the high temperatures during launches results in frequent and costly repairs and safety hazards. KSC-SPEC-P-0012, Specification for Refractory Concrete, is ineffective in qualifying refractory materials. This study of the specification and of alternative refractory materials recommends a complete revision of the specification and further investigation of materials that were found to withstand the environment of the Solid Rocket Booster main flame deflector better than the refractory materials in current use in terms of compressive strength, tensile strength, modulus of rupture, shrinkage, and abrasion.

Use of a corrugated beam pipe as a passive deflector for bunch length measurements

NASA Astrophysics Data System (ADS)

Seok, Jimin; Chung, Moses; Kang, Heung-Sik; Min, Chang-Ki; Na, Donghyun

2018-02-01

We report the experimental demonstration of bunch length measurements using a corrugated metallic beam pipe as a passive deflector. The corrugated beam pipe has been adopted for reducing longitudinal chirping after the bunch compressors in several XFEL facilities worldwide. In the meantime, there have been attempts to measure the electron bunch's longitudinal current profile using the dipole wakefields generated in the corrugated pipe. Nevertheless, the bunch shape reconstructed from the nonlinearly deflected beam suffers from significant distortion, particularly near the head of the bunch. In this paper, we introduce an iterative process to improve the resolution of the bunch shape reconstruction. The astra and elegant simulations have been performed for pencil beam and cigar beam cases, in order to verify the effectiveness of the reconstruction process. To overcome the undesirable effects of transverse beam spreads, a measurement scheme involving both the corrugated beam pipe and the spectrometer magnet has been employed, both of which do not require a dedicated (and likely very expensive) rf system. A proof-of-principle experiment was carried out at Pohang Accelerator Laboratory (PAL) Injector Test Facility (ITF), and its results are discussed together with a comparison with the rf deflector measurement.

Hysteresis of the Contact Angle of a Meniscus Inside a Capillary with Smooth, Homogeneous Solid Walls.

PubMed

Kuchin, Igor V; Starov, Victor M

2016-05-31

A theory of contact angle hysteresis of a meniscus inside thin capillaries with smooth, homogeneous solid walls is developed in terms of surface forces (disjoining/conjoining pressure isotherm) using a quasi-equilibrium approach. The disjoining/conjoining pressure isotherm includes electrostatic, intermolecular, and structural components. The values of the static receding θr, advancing θa, and equilibrium θe contact angles in thin capillaries were calculated on the basis of the shape of the disjoining/conjoining pressure isotherm. It was shown that both advancing and receding contact angles depend on the capillary radius. The suggested mechanism of the contact angle hysteresis has a direct experimental confirmation: the process of receding is accompanied by the formation of thick β-films on the capillary walls. The effect of the transition from partial to complete wetting in thin capillaries is predicted and analyzed. This effect takes place in very thin capillaries, when the receding contact angle decreases to zero.

Fusion hindrance for the positive Q -value system 12C+30Si

NASA Astrophysics Data System (ADS)

Montagnoli, G.; Stefanini, A. M.; Jiang, C. L.; Hagino, K.; Galtarossa, F.; Colucci, G.; Bottoni, S.; Broggini, C.; Caciolli, A.; Čolović, P.; Corradi, L.; Courtin, S.; Depalo, R.; Fioretto, E.; Fruet, G.; Gal, A.; Goasduff, A.; Heine, M.; Hu, S. P.; Kaur, M.; Mijatović, T.; Mazzocco, M.; Montanari, D.; Scarlassara, F.; Strano, E.; Szilner, S.; Zhang, G. X.

2018-02-01

Background: The fusion reaction 12C+30Si is a link between heavier cases studied in recent years, and the light heavy-ion systems, e.g., 12C+12C , 16O+16O that have a prominent role in the dynamics of stellar evolution. 12C+30Si fusion itself is not a relevant process for astrophysics, but it is important to establish its behavior below the barrier, where couplings to low-lying collective modes and the hindrance phenomenon may determine the cross sections. The excitation function is presently completely unknown below the barrier for the 12C+30Si reaction, thus no reliable extrapolation into the astrophysical regime for the C+C and O+O cases can be performed. Purpose: Our aim was to carry out a complete measurement of the fusion excitation function of 12C+30Si from well below to above the Coulomb barrier, so as to clear up the consequence of couplings to low-lying states of 30Si, and whether the hindrance effect appears in this relatively light system which has a positive Q value for fusion. This would have consequences for the extrapolated behavior to even lighter systems. Methods: The inverse kinematics was used by sending 30Si beams delivered from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro onto thin 12C (50 μ g /cm2 ) targets enriched to 99.9 % in mass 12. The fusion evaporation residues (ER) were detected at very forward angles, following beam separation by means of an electrostatic deflector. Angular distributions of ER were measured at Ebeam=45 , 59, and 80 MeV, and they were angle integrated to derive total fusion cross sections. Results: The fusion excitation function of 12C+30Si was measured with high statistical accuracy, covering more than five orders of magnitude down to a lowest cross section ≃3 μ b . The logarithmic slope and the S factor have been extracted and we have convincing phenomenological evidence of the hindrance effect. These results have been compared with the calculations performed within the model that considers a damping of the coupling strength well inside the Coulomb barrier. Conclusions: The experimental data are consistent with the coupled-channels calculations. A better fit is obtained by using the Yukawa-plus-exponential potential and a damping of the coupling strengths inside the barrier. The degree of hindrance is much smaller than the one in heavier systems. Also a phenomenological estimate reproduces quite closely the hindrance threshold for 12C+30Si , so that an extrapolation to the C+C and O+O cases can be reliably performed.

Zipping dielectric elastomer actuators: characterization, design and modeling

NASA Astrophysics Data System (ADS)

Maffli, L.; Rosset, S.; Shea, H. R.

2013-10-01

We report on miniature dielectric elastomer actuators (DEAs) operating in zipping mode with an analytical model that predicts their behavior. Electrostatic zipping is a well-known mechanism in silicon MEMS to obtain large deformations and forces at lower voltages than for parallel plate electrostatic actuation. We extend this concept to DEAs, which allows us to obtain much larger out-of-plane displacements compared to silicon thanks to the softness of the elastomer membrane. We study experimentally the effect of sidewall angles and elastomer prestretch on 2.3 mm diameter actuators with PDMS membranes. With 15° and 22.5° sidewall angles, the devices zip in a bistable manner down 300 μm to the bottom of the chambers. The highly tunable bistable behavior is controllable by both chamber geometry and membrane parameters. Other specific characteristics of zipping DEAs include well-controlled deflected shape, tunable displacement versus voltage characteristics to virtually any shape, including multi-stable modes, sealing of embedded holes or channels for valving action and the reduction of the operating voltage. These properties make zipping DEAs an excellent candidate for applications such as integrated microfluidics actuators or Braille displays.

Failure Analysis of Main Flame Deflector Nelson Studs

NASA Technical Reports Server (NTRS)

Long, Victoria

2009-01-01

NASA Structures engineers submitted two Nelson refractory studs from the main flame deflector at Launch Complex (LC) 39 A for analysis when they were observed to be missing a significant amount of material after launch. The damaged stud and an unused comparative stud were analyzed by macroscopic and microscopic examination along with metallographic evaluation of the microstructure. The stud lost material due to a combination of erosion and corrosion. Plain carbon steel readily forms an oxide layer in the coastal launch environment at Kennedy Space Center. The blast during a launch removes this brittle oxide layer, which then forms again post-launch, thereby further removing material. No indications of melting were observed.

Ultra-fast 3D scanning and holographic illumination in non-linear microscopy using acousto-optic deflectors

NASA Astrophysics Data System (ADS)

Akemann, Walther; Ventalon, Cathie; Léger, Jean-François; Mathieu, Benjamin; Dieudonné, Stéphane; Blochet, Baptiste; Gigan, Sylvain; Bourdieu, Laurent

2017-04-01

Decoding of information in the brain requires the imaging of large neuronal networks using e.g. two-photon microscopy (TPM). Fast control of the focus in 3D can be achieved with phase shaping of the light beam using acoustooptic deflectors (AODs). However, beam shaping using AODs is not straightforward because of non-stationary of acousto-optic diffraction. Here, we demonstrated a new stable AOD-based phase modulator, which operates at a rate of up to about hundred kHz. It provides opportunity for 3D scanning in TPM with the possibility to correct aberrations independently for every focus position or to achieve refocusing of scattered photons in rapidly decorrelating tissues.

Ultrashort electron bunch length measurement with diffraction radiation deflector

NASA Astrophysics Data System (ADS)

Xiang, Dao; Huang, Wen-Hui

2007-01-01

In this paper, we propose a novel method to measure electron bunch length with a diffraction radiation (DR) deflector which is composed of a DR radiator and three beam position monitors (BPMs). When an electron beam passes through a metallic aperture which is tilted by 45 degrees with respect to its trajectory, backward DR that propagates perpendicular to the beam’s trajectory is generated which adds a transverse deflection to the beam as a result of momentum conservation. The deflection is found to be largely dependent on the bunch length and could be easily observed with a downstream BPM. Detailed investigations show that this method has wide applicability, high temporal resolution, and great simplicity.

Molecular Dynamics Simulation of Membranes and a Transmembrane Helix

NASA Astrophysics Data System (ADS)

Duong, Tap Ha; Mehler, Ernest L.; Weinstein, Harel

1999-05-01

Three molecular dynamics (MD) simulations of 1.5-ns length were carried out on fully hydrated patches of dimyristoyl phosphatidylcholine (DMPC) bilayers in the liquid-crystalline phase. The simulations were performed using different ensembles and electrostatic conditions: a microcanonical ensemble or constant pressure-temperature ensemble, with or without truncated electrostatic interactions. Calculated properties of the membrane patches from the three different protocols were compared to available data from experiments. These data include the resulting overall geometrical dimensions, the order characteristics of the lipid hydrocarbon chains, as well as various measures of the conformations of the polar head groups. The comparisons indicate that the simulation carried out within the microcanonical ensemble with truncated electrostatic interactions yielded results closest to the experimental data, provided that the initial equilibration phase preceding the production run was sufficiently long. The effects of embedding a non-ideal helical protein domain in the membrane patch were studied with the same MD protocols. This simulation was carried out for 2.5 ns. The protein domain corresponds to the seventh transmembrane segment (TMS7) of the human serotonin 5HT 2Areceptor. The peptide is composed of two α-helical segments linked by a hinge domain around a perturbing Asn-Pro motif that produces at the end of the simulation a kink angle of nearly 80° between the two helices. Several aspects of the TMS7 structure, such as the bending angle, backbone Φ and Ψ torsion angles, the intramolecular hydrogen bonds, and the overall conformation, were found to be very similar to those determined by NMR for the corresponding transmembrane segment of the tachykinin NK-1 receptor. In general, the simulations were found to yield structural and dynamic characteristics that are in good agreement with experiment. These findings support the application of simulation methods to the study of the complex biomolecular systems at the membrane interface of cells.

Klein tunneling in the α -T3 model

NASA Astrophysics Data System (ADS)

Illes, E.; Nicol, E. J.

2017-06-01

We investigate Klein tunneling for the α -T3 model, which interpolates between graphene and the dice lattice via parameter α . We study transmission across two types of electrostatic interfaces: sharp potential steps and sharp potential barriers. We find both interfaces to be perfectly transparent for normal incidence for the full range of the parameter α for both interfaces. For other angles of incidence, we find that transmission is enhanced with increasing α . For the dice lattice, we find perfect, all-angle transmission across a potential step for incoming electrons with energy equal to half of the height of the potential step. This is analogous to the "super", all-angle transmission reported for the dice lattice for Klein tunneling across a potential barrier.

Single DMD time-multiplexed 64-views autostereoscopic 3D display

NASA Astrophysics Data System (ADS)

Loreti, Luigi

2013-03-01

Based on previous prototype of the Real time 3D holographic display developed last year, we developed a new concept of auto-stereoscopic multiview display (64 views), wide angle (90°) 3D full color display. The display is based on a RGB laser light source illuminating a DMD (Discovery 4100 0,7") at 24.000 fps, an image deflection system made with an AOD (Acoustic Optic Deflector) driven by a piezo-electric transducer generating a variable standing acoustic wave on the crystal that acts as a phase grating. The DMD projects in fast sequence 64 point of view of the image on the crystal cube. Depending on the frequency of the standing wave, the input picture sent by the DMD is deflected in different angle of view. An holographic screen at a proper distance diffuse the rays in vertical direction (60°) and horizontally select (1°) only the rays directed to the observer. A telescope optical system will enlarge the image to the right dimension. A VHDL firmware to render in real-time (16 ms) 64 views (16 bit 4:2:2) of a CAD model (obj, dxf or 3Ds) and depth-map encoded video images was developed into the resident Virtex5 FPGA of the Discovery 4100 SDK, thus eliminating the needs of image transfer and high speed links

Systematic flow manipulation by a deflector-turbine array

NASA Astrophysics Data System (ADS)

Mandre, Shreyas; Mangan, Niall M.

2017-11-01

Wind and hydrokinetic turbines are often installed in the wake of upstream turbines that limit the energy incident on the downstream ones. In two-dimensions, we describe how an array can deflect the wake away and redirect more energy to itself. Using inviscid fluid dynamics, we formulate the definitions of ``deflectors'' and ``turbines'' as elements that introduce bound and shed vorticity in the flow, respectively. To illustrate the flow manipulation, we consider a deflector-turbine array constrained to a line segment aligned with the freestream and acting as an internal boundary. We impose profiles of bound and shed vorticity on this segment that parameterize the flow deflection and the wake deficit respectively, and analyze the resulting flow using inviscid fluid dynamics. We find that the power extracted by the array is the product of two components: (i) the deflected kinetic energy incident on the array, and (ii) the array efficiency, or its ability to extract a fraction of the incident energy, both of which vary with deflection strength. The array efficiency decreases slightly with increasing deflection from about 57% at weak deflection to 39% at high deflection. This decrease is outweighed by an increase in the incident kinetic energy due to deflection. Funded by the Advanced Research Projects Agency - Energy.

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

García-Cervantes, H.; Sotolongo-Costa, O.; Gaggero-Sager, L. M.

Graphene Superlattices (GSs) have attracted a lot of attention due to its peculiar properties as well as its possible technological implications. Among these characteristics we can mention: the extra Dirac points in the dispersion relation and the highly anisotropic propagation of the charge carriers. However, despite the intense research that is carried out in GSs, so far there is no report about the angular dependence of the Transmission Gap (TG) in GSs. Here, we report the dependence of TG as a function of the angle of the incident Dirac electrons in a rather simple Electrostatic GS (EGS). Our results showmore » that the angular dependence of the TG is intricate, since for moderated angles the dependence is parabolic, while for large angles an exponential dependence is registered. We also find that the TG can be modulated from meV to eV, by changing the structural parameters of the GS. These characteristics open the possibility for an angle-dependent bandgap engineering in graphene.« less

Implementation of spatial overlap modulation nonlinear optical microscopy using an electro-optic deflector

PubMed Central

Isobe, Keisuke; Kawano, Hiroyuki; Kumagai, Akiko; Miyawaki, Atsushi; Midorikawa, Katsumi

2013-01-01

A spatial overlap modulation (SPOM) technique is a nonlinear optical microscopy technique which enhances the three-dimensional spatial resolution and rejects the out-of-focus background limiting the imaging depth inside a highly scattering sample. Here, we report on the implementation of SPOM in which beam pointing modulation is achieved by an electro-optic deflector. The modulation and demodulation frequencies are enhanced to 200 kHz and 400 kHz, respectively, resulting in a 200-fold enhancement compared with the previously reported system. The resolution enhancement and suppression of the out-of-focus background are demonstrated by sum-frequency-generation imaging of pounded granulated sugar and deep imaging of fluorescent beads in a tissue-like phantom, respectively. PMID:24156055

Pad A Main Flame Deflector Sensor Data and Evaluation

NASA Technical Reports Server (NTRS)

Parlier, Christopher R.

2011-01-01

Space shuttle launch pads use flame deflectors beneath the vehicle to channel hot gases away from the vehicle. Pad 39 A at the Kennedy Space Center uses a steel structure coated with refractory concrete. The solid rocket booster plume is comprised of gas and molten alumina oxide particles that erodes the refractory concrete. During the beginning of the shuttle program the loads for this system were never validated with a high level of confidence. This paper presents a representation of the instrumentation data collected and follow on materials science evaluation of the materials exposed to the SRB plume. Data collected during STS-133 and STS-134 will be presented that support the evaluation of the components exposed to the SRB plume.

Isotopic effects in sub-barrier fusion of Si + Si systems

NASA Astrophysics Data System (ADS)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Esbensen, H.; Bourgin, D.; Čolović, P.; Corradi, L.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Szilner, S.; Urbani, M.; Zhang, G. L.

2018-04-01

Background: Recent measurements of fusion cross sections for the 28Si+28Si system revealed a rather unsystematic behavior; i.e., they drop faster near the barrier than at lower energies. This was tentatively attributed to the large oblate deformation of 28Si because coupled-channels (CC) calculations largely underestimate the 28Si+28Si cross sections at low energies, unless a weak imaginary potential is applied, probably simulating the deformation. 30Si has no permanent deformation and its low-energy excitations are of a vibrational nature. Previous measurements of this system reached only 4 mb, which is not sufficient to obtain information on effects that should show up at lower energies. Purpose: The aim of the present experiment was twofold: (i) to clarify the underlying fusion dynamics by measuring the symmetric case 30Si+30Si in an energy range from around the Coulomb barrier to deep sub-barrier energies, and (ii) to compare the results with the behavior of 28Si+28Si involving two deformed nuclei. Methods: 30Si beams from the XTU tandem accelerator of the Laboratori Nazionali di Legnaro of the Istituto Nazionale di Fisica Nucleare were used, bombarding thin metallic 30Si targets (50 μ g /cm2) enriched to 99.64 % in mass 30. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ERs) at very forward angles, and angular distributions of ERs were measured. Results: The excitation function of 30Si+30Si was measured down to the level of a few microbarns. It has a regular shape, at variance with the unusual trend of 28Si+28Si . The extracted logarithmic derivative does not reach the LCS limit at low energies, so that no maximum of the S factor shows up. CC calculations were performed including the low-lying 2+ and 3- excitations. Conclusions: Using a Woods-Saxon potential the experimental cross sections at low energies are overpredicted, and this is a clear sign of hindrance, while the calculations performed with a M3Y + repulsion potential nicely fit the data at low energies, without the need of an imaginary potential. The comparison with the results for 28Si+28Si strengthens the explanation of the oblate shape of 28Si being the reason for the irregular behavior of that system.

An electrostatically and a magnetically confined electron gun lens system

NASA Technical Reports Server (NTRS)

Bernius, Mark T.; Man, Kin F.; Chutjian, Ara

1988-01-01

Focal properties, electron trajectory calculations, and geometries are given for two electron 'gun' lens systems that have a variety of applications in, for example, electron-neutral and electron-ion scattering experiments. One nine-lens system utilizes only electrostatic confinement and is capable of focusing electrons onto a fixed target with extremely small divergence angles, over a range of final energies 1-790 eV. The second gun lens system is a simpler three-lens system suitable for use in a uniform, solenoidal magnetic field. While the focusing properties of such a magnetically confined lens systenm are simpler to deal with, the system does illustrate features of electron extraction and Brillouin flow that have not been suitably emphasized in the literature.

Sub-barrier fusion of Si+Si systems

NASA Astrophysics Data System (ADS)

Colucci, G.; Montagnoli, G.; Stefanini, A. M.; Bourgin, D.; Čolović, P.; Corradi, L.; Courtin, S.; Faggian, M.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Haas, F.; Mazzocco, M.; Scarlassara, F.; Stefanini, C.; Strano, E.; Urbani, M.; Szilner, S.; Zhang, G. L.

2017-11-01

The near- and sub-barrier fusion excitation function has been measured for the system 30Si+30Si at the Laboratori Nazionali di Legnaro of INFN, using the 30Si beam of the XTU Tandem accelerator in the energy range 47 - 90 MeV. A set-up based on a beam electrostatic deflector was used for detecting fusion evaporation residues. The measured cross sections have been compared to previous data on 28Si+28Si and Coupled Channels (CC) calculations have been performed using M3Y+repulsion and Woods-Saxon potentials, where the lowlying 2+ and 3- excitations have been included. A weak imaginary potential was found to be necessary to reproduce the low energy 28Si+28Si data. This probably simulates the effect of the oblate deformation of this nucleus. On the contrary, 30Si is a spherical nucleus, 30Si+30Si is nicely fit by CC calculations and no imaginary potential is needed. For this system, no maximum shows up for the astrophysical S-factor so that we have no evidence for hindrance, as confirmed by the comparison with CC calculations. The logarithmic derivative of the two symmetric systems highlights their different low energy trend. A difference can also be noted in the two barrier distributions, where the high-energy peak present in 28Si+28Si is not observed for 30Si+30Si, probably due to the weaker couplings in last case.

Optimising electron microscopy experiment through electron optics simulation.

PubMed

Kubo, Y; Gatel, C; Snoeck, E; Houdellier, F

2017-04-01

We developed a new type of electron trajectories simulation inside a complete model of a modern transmission electron microscope (TEM). Our model incorporates the precise and real design of each element constituting a TEM, i.e. the field emission (FE) cathode, the extraction optic and acceleration stages of a 300kV cold field emission gun, the illumination lenses, the objective lens, the intermediate and projection lenses. Full trajectories can be computed using magnetically saturated or non-saturated round lenses, magnetic deflectors and even non-cylindrical symmetry elements like electrostatic biprism. This multi-scale model gathers nanometer size components (FE tip) with parts of meter length (illumination and projection systems). We demonstrate that non-trivial TEM experiments requiring specific and complex optical configurations can be simulated and optimized prior to any experiment using such model. We show that all the currents set in all optical elements of the simulated column can be implemented in the real column (I2TEM in CEMES) and used as starting alignment for the requested experiment. We argue that the combination of such complete electron trajectory simulations in the whole TEM column with automatic optimization of the microscope parameters for optimal experimental data (images, diffraction, spectra) allows drastically simplifying the implementation of complex experiments in TEM and will facilitate the development of advanced use of the electron microscope in the near future. Copyright © 2017 Elsevier B.V. All rights reserved.

In-depth study of in-trap high-resolution mass separation by transversal ion ejection from a multi-reflection time-of-flight device.

PubMed

Fischer, Paul; Knauer, Stefan; Marx, Gerrit; Schweikhard, Lutz

2018-01-01

The recently introduced method of ion separation by transversal ejection of unwanted species in electrostatic ion-beam traps and multi-reflection time-of-flight devices has been further studied in detail. As this separation is performed during the ion storage itself, there is no need for additional external devices such as ion gates or traps for either pre- or postselection of the ions of interest. The ejection of unwanted contaminant ions is performed by appropriate pulses of the potentials of deflector electrodes. These segmented ring electrodes are located off-center in the trap, i.e., between one of the two ion mirrors and the central drift tube, which also serves as a potential lift for capturing incoming ions and axially ejecting ions of interest after their selection. The various parameters affecting the selection effectivity and resolving power are illustrated with tin-cluster measurements, where isotopologue ion species provide mass differences down to a single atomic mass unit at ion masses of several hundred. Symmetric deflection voltages of only 10 V were found sufficient for the transversal ejection of ion species with as few as three deflection pulses. The duty cycle, i.e., the pulse duration with respect to the period of ion revolution, has been varied, resulting in resolving powers of up to several tens of thousands for this selection technique.

In-depth study of in-trap high-resolution mass separation by transversal ion ejection from a multi-reflection time-of-flight device

NASA Astrophysics Data System (ADS)

Fischer, Paul; Knauer, Stefan; Marx, Gerrit; Schweikhard, Lutz

2018-01-01

The recently introduced method of ion separation by transversal ejection of unwanted species in electrostatic ion-beam traps and multi-reflection time-of-flight devices has been further studied in detail. As this separation is performed during the ion storage itself, there is no need for additional external devices such as ion gates or traps for either pre- or postselection of the ions of interest. The ejection of unwanted contaminant ions is performed by appropriate pulses of the potentials of deflector electrodes. These segmented ring electrodes are located off-center in the trap, i.e., between one of the two ion mirrors and the central drift tube, which also serves as a potential lift for capturing incoming ions and axially ejecting ions of interest after their selection. The various parameters affecting the selection effectivity and resolving power are illustrated with tin-cluster measurements, where isotopologue ion species provide mass differences down to a single atomic mass unit at ion masses of several hundred. Symmetric deflection voltages of only 10 V were found sufficient for the transversal ejection of ion species with as few as three deflection pulses. The duty cycle, i.e., the pulse duration with respect to the period of ion revolution, has been varied, resulting in resolving powers of up to several tens of thousands for this selection technique.

The Solar Wind Ion Analyzer for MAVEN

NASA Astrophysics Data System (ADS)

Halekas, J. S.; Taylor, E. R.; Dalton, G.; Johnson, G.; Curtis, D. W.; McFadden, J. P.; Mitchell, D. L.; Lin, R. P.; Jakosky, B. M.

2015-12-01

The Solar Wind Ion Analyzer (SWIA) on the MAVEN mission will measure the solar wind ion flows around Mars, both in the upstream solar wind and in the magneto-sheath and tail regions inside the bow shock. The solar wind flux provides one of the key energy inputs that can drive atmospheric escape from the Martian system, as well as in part controlling the structure of the magnetosphere through which non-thermal ion escape must take place. SWIA measurements contribute to the top level MAVEN goals of characterizing the upper atmosphere and the processes that operate there, and parameterizing the escape of atmospheric gases to extrapolate the total loss to space throughout Mars' history. To accomplish these goals, SWIA utilizes a toroidal energy analyzer with electrostatic deflectors to provide a broad 360∘×90∘ field of view on a 3-axis spacecraft, with a mechanical attenuator to enable a very high dynamic range. SWIA provides high cadence measurements of ion velocity distributions with high energy resolution (14.5 %) and angular resolution (3.75∘×4.5∘ in the sunward direction, 22.5∘×22.5∘ elsewhere), and a broad energy range of 5 eV to 25 keV. Onboard computation of bulk moments and energy spectra enable measurements of the basic properties of the solar wind at 0.25 Hz.

High Power HF Excitation of Low Frequency Stimulated Electrostatic Waves in the Ionospheric Plasma over HAARP

NASA Astrophysics Data System (ADS)

Bernhardt, Paul; Selcher, Craig A.

High Power electromagnetic (EM) waves transmitted from the HAARP facility in Alaska can excite low frequency electrostatic waves by several processes including (1) direct magnetized stimulated Brillouin scatter (MSBS) and (2) parametric decay of high frequency electrostatic waves into electron and ion Bernstein waves. Either an ion acoustic (IA) wave with a frequency less than the ion cyclotron frequency (fCI) or an electrostatic ion cyclotron (EIC) wave just above fCI can be produced by MSBS. The coupled equations describing the MSBS instabil-ity show that the production of both IA and EIC waves is strongly influenced by the wave propagation direction relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions (SEE) using the HAARP transmitter in Alaska have confirmed the theoretical predictions that only IA waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The electron temperature in the heated plasma is obtained from the IA spectrum offsets from the pump frequency. The ion composition can be determined from the measured EIC frequency. Near the second harmonic of the electron cyclotron frequency, the EM pump wave is converted into an electron Bernstein (EB) wave that decays into another EB wave and an ion Bernstein (IB) wave. Strong cyclotron resonance with the EB wave leads to acceleration of the electrons. Ground based SEE observations are related to the theory of low-frequency electrostatic wave generation.

Electrostatic Properties of Polymers Subjected to Atmospheric Pressure Plasma Treatment; Correlation of Experimental Results with Atomistic Modeling

NASA Technical Reports Server (NTRS)

Trigwell, S.; Boucher, D.; Calle, C. I.

2007-01-01

this study, PE, PTFE, PS and PMMA were exposed to a He+O2, APGD and pre and post treatment surface chemistries were analyzed by X-ray photoelectron spectroscopy and contact angle measurements. Semi-empirical and ab-initio calculations were performed to correlate the experimental results with sonic plausible molecular and electronic structure features of the oxidation process. For the PE and PS, significant surface oxidation showing C-O, C=O, and O-C=O bonding, and a decrease in the surface contact angles was observed. For the PTFE and PM MA, little change in the surface composition was observed. The molecular modeling calculations were performed on single and multiple oligomers and showed regardless of oxidation mechanism, e.g. -OH, =O or a combination thereof, experimentally observed levels of surface oxidation were unlikely to lead to a significant change in the electronic structure of PE and PS, and that the increased hydrophilic properties are the primary reason for the observed changes in its electrostatic behavior. Calculations for PTFE and PMMA argue strongly against significant oxidation of those materials, as confirmed by the XPS results.

Field-aligned electrostatic potential differences on the Martian night side

NASA Astrophysics Data System (ADS)

Lillis, Rob; Collinson, Glyn; Mitchell, David

2017-04-01

Field-aligned electrostatic potential differences on the Martian night side above 170 km can be inferred with the aid of a kinetic electron transport model and in a statistical sense, by energy-dependent angular shifts in electron loss cones measured in Mars orbit. Potentials between 170 km and 400 km derived from pitch angle distributions measured by the Mars Global Surveyor (MGS) Magnetometer/ Electron Reflectometer experiment (MAG/ER) at 2 a.m. local time are typically small (-10 V to 10 V) but can reach magnitudes of >100 V. Geographically, the strongest negative potential differences (with mean values up to -50 V) are preferentially observed at the boundaries between open and closed strong magnetic field regions, while positive potential differences are preferentially observed further from open field lines. These characteristics may reflect current systems closing at high altitude through cross-tail currents and at low altitude in the conducting night side ionosphere. We will present a synthesis of potentials derived from pitch angle distributions measured by both MGS MAG/ER as mentioned above, and by the MAVEN Solar Wind Electron Analyzer (SWEA) collected at a range of local times and altitudes.

Ion beamlet steering for two-grid electrostatic thrusters. M.S. Thesis

NASA Technical Reports Server (NTRS)

Homa, J. M.

1984-01-01

An experimental study of ion beamlet steering in which the direction of beamlets emitted from a two grid aperture system is controlled by relative translation of the grids, is described. The results can be used to design electrostatic accelerating devices for which the direction and focus of emerging beamlets are important. Deflection and divergence angle data are presented for two grid systems as a function of the relative lateral displacement of the holes in these grids. At large displacements, accelerator grid impingements become excessive and this determines the maximum allowable displacement and as a result the useful range of beamlet deflection. Beamlet deflection is shown to vary linearly with grid offset angle over this range. The divergence of the beamlets is found to be unaffected by deflection over the useful range of beamlet deflection. The grids of a typical dished grid ion thruster are examined to determine the effects of thermally induced grid distortion and prescribed offsets of grid hole centerlines on the characteristics of the emerging beamlets. The results are used to determine the region on the grid surface where ion beamlet deflections exceed the useful range. Over this region high accelerator grid impingement currents and rapid grid erosion are predicted.

Design of beam deflector, splitters, wave plates and metalens using photonic elements with dielectric metasurface

NASA Astrophysics Data System (ADS)

Zhang, Qing; Li, Maozhong; Liao, Tingdi; Cui, Xudong

2018-03-01

Under the trend of miniaturization and reduction of system complexity, conventional bulky photonic elements are expected to be replaced by new compact and ultrathin dielectric metasurface elements. In this letter, we propose an αTiO2 dielectric metasurface (DM) platform that could be exploited to design high efficiency wave-front control devices at visible wavelength. Combining with fundamental principles and full wave simulations (Lumerical FDTD 3D solver ®), we successfully realize four DM devices, such as anomalous beam deflectors, polarization insensitive metalens, wave plates and polarization beam splitters. All these devices can achieve high transmission efficiencies (larger than 80%). Among them, the anomalous refraction beam deflectors can bend light propagation to any desired directions; the polarization insensitive metalens maintains diffraction limited focus (focal spot as small as 0.67 λ); the quarter-wave and half-wave plates have broadband working wavelengths from 550 to 1000 nm; and the polarization beam splitter can split an arbitrarily polarized incident beam into two orthogonally polarized beams, the TM components is deflected to the right side, and the TE components is deflected to the left side. These devices may find applications in the areas of imaging, polarization control, spectroscopy, and on-chip optoelectronic systems etc., and our studies may richen the design of all-dielectric optical elements at visible wavelength.

Molecular insight into the electrostatic membrane surface potential by 14n/31p MAS NMR spectroscopy: nociceptin-lipid association.

PubMed

Lindström, Fredrick; Williamson, Philip T F; Gröbner, Gerhard

2005-05-11

Exploiting naturally abundant (14)N and (31)P nuclei by high-resolution MAS NMR (magic angle spinning nuclear magnetic resonance) provides a molecular view of the electrostatic potential present at the surface of biological model membranes, the electrostatic charge distribution across the membrane interface, and changes that occur upon peptide association. The spectral resolution in (31)P and (14)N MAS NMR spectra is sufficient to probe directly the negatively charged phosphate and positively charged choline segment of the electrostatic P(-)-O-CH(2)-CH(2)-N(+)(CH(3))(3) headgroup dipole of zwitterionic DMPC (dimyristoylphosphatidylcholine) in mixed-lipid systems. The isotropic shifts report on the size of the potential existing at the phosphate and ammonium group within the lipid headgroup while the chemical shielding anisotropy ((31)P) and anisotropic quadrupolar interaction ((14)N) characterize changes in headgroup orientation in response to surface potential. The (31)P/(14)N isotropic chemical shifts for DMPC show opposing systematic changes in response to changing membrane potential, reflecting the size of the electrostatic potential at opposing ends of the P(-)-N(+) dipole. The orientational response of the DMPC lipid headgroup to electrostatic surface variations is visible in the anisotropic features of (14)N and (31)P NMR spectra. These features are analyzed in terms of a modified "molecular voltmeter" model, with changes in dynamic averaging reflecting the tilt of the C(beta)-N(+)(CH)(3) choline and PO(4)(-) segment. These properties have been exploited to characterize the changes in surface potential upon the binding of nociceptin to negatively charged membranes, a process assumed to proceed its agonistic binding to its opoid G-protein coupled receptor.

Measurement of differential cross section of D(3He,p)4He from 0.8 MeV to 3.6 MeV

NASA Astrophysics Data System (ADS)

Zhu, J. P.; Xiao, X.; Yan, S.; Gao, Y.; Xue, J. M.; Wang, Y. G.

2017-12-01

Precise knowledge of the nuclear reaction cross-section is crucial for nuclear reaction analysis methods and its applications. In order to apply nuclear reaction analysis methods to Plasma Facing Materials studies on 4.5 MV electrostatic accelerator at Peking University, differential cross-section for d(3He,p) α at several backward angles was measured with a relative error about ± 6.2 % , gives detailed information at the laboratory angle of 135° from 800 keV to 3600 keV, as well as a rough angular distribution from 130° to 160°.

Electro-optic Waveguide Beam Deflector.

DTIC Science & Technology

beam deflection by variation in the electro - optic effect produced within the waveguide region in response to known or determinable magnitude variations in the electrical potential of an applied signal source.

Acoustic investigation of the engine-over-the-wing concept using a D-shaped nozzle.

NASA Technical Reports Server (NTRS)

Reshotko, M.; Friedman, R.

1973-01-01

Small-model experiments were conducted of the engine-over-the-wing concept using a D-shaped nozzle in order to determine the static-lift and acoustic characteristics at two wing-flap positions. Configurations were tested with the flow attached and unattached to the upper surface of the flaps. Attachment was obtained with a nozzle flow deflector. In both cases, high frequency noise shielding by the wing was obtained. Configurations using the D-shaped nozzle are compared with corresponding ones using a circular nozzle. With flow attached to the flaps, the static lift and acoustic results are almost the same for both nozzles. Without the nozzle flow deflector (unattached flap flow), the D-nozzle is considerably noisier than a circular nozzle in the low and middle frequencies.

Ultrafast, large-field multiphoton microscopy based on an acousto-optic deflector and a spatial light modulator.

PubMed

Shao, Yonghong; Qin, Wan; Liu, Honghai; Qu, Junle; Peng, Xiang; Niu, Hanben; Gao, Bruce Z

2012-07-01

We present an ultrafast, large-field multiphoton excitation fluorescence microscope with high lateral and axial resolutions based on a two-dimensional (2-D) acousto-optical deflector (AOD) scanner and spatial light modulator (SLM). When a phase-only SLM is used to shape the near-infrared light from a mode-locked titanium:sapphire laser into a multifocus array including the 0-order beam, a 136 μm × 136 μm field of view is achieved with a 60× objective using a 2-D AOD scanner without any mechanical scan element. The two-photon fluorescence image of a neuronal network that was obtained using this system demonstrates that our microscopy permits observation of dynamic biological events in a large field with high-temporal and -spatial resolution.

A flange on electron spectromicroscope with spherical deflector analyzer--simultaneous imaging of reciprocal and real spaces.

PubMed

Grzelakowski, Krzysztof P

2013-07-01

An instrumental realization of the idea for the electron emission spectromicroscope based on the newly developed imaging energy filter called α-SDA (Spherical Deflector Analyzer) is reported. Its compact design enables the realization of the flange-on spectromicroscope concept. It is equipped with two independent energy selective imaging channels: one for real and another for reciprocal space visualization. These images can be acquired quasi-simultaneousely by means of the software based on the switching on and off potentials of the energy filter. An electron gun located inside the immersion objective lens allows a new kind of sample illumination by high energy primary electrons and thus, opens a new application field for electron spectromicroscopy under laboratory conditions. Copyright © 2013 Elsevier B.V. All rights reserved.

A programmable light engine for quantitative single molecule TIRF and HILO imaging.

PubMed

van 't Hoff, Marcel; de Sars, Vincent; Oheim, Martin

2008-10-27

We report on a simple yet powerful implementation of objective-type total internal reflection fluorescence (TIRF) and highly inclined and laminated optical sheet (HILO, a type of dark-field) illumination. Instead of focusing the illuminating laser beam to a single spot close to the edge of the microscope objective, we are scanning during the acquisition of a fluorescence image the focused spot in a circular orbit, thereby illuminating the sample from various directions. We measure parameters relevant for quantitative image analysis during fluorescence image acquisition by capturing an image of the excitation light distribution in an equivalent objective backfocal plane (BFP). Operating at scan rates above 1 MHz, our programmable light engine allows directional averaging by circular spinning the spot even for sub-millisecond exposure times. We show that restoring the symmetry of TIRF/HILO illumination reduces scattering and produces an evenly lit field-of-view that affords on-line analysis of evanescnt-field excited fluorescence without pre-processing. Utilizing crossed acousto-optical deflectors, our device generates arbitrary intensity profiles in BFP, permitting variable-angle, multi-color illumination, or objective lenses to be rapidly exchanged.

Offutt Air Force Base, Looking Glass Airborne Command Post, Blast ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Offutt Air Force Base, Looking Glass Airborne Command Post, Blast Deflector Fences, Northeast & Southwest sides of Operational Apron, Project Looking Glass Historic District, Bellevue, Sarpy County, NE

An improved patch for radiative coolers

NASA Astrophysics Data System (ADS)

Bly, Vincent T.

1993-09-01

A unique structure for constructing the emissive patch of a spaceborne radiative cooler is shown. The structure has very high emissivity for all angles up to a designed-in maximum angle and near zero emissivity for greater angles. The structure also allows the use of high emissivity, nonconducting paints while fully complying with the NASA Electrostatic Discharge Susceptibility requirements for spacecraft. To accomplish these tasks, two previous disadvantages of prior art methods are addressed; eliminating background thermal radiation sources and problems concerning the high emissivity paints used in association with the black body radiator. A reflector consisting of an array of parabolic concentrators is separated from a black body element by an electrically conductive spacer. The concentrators serve to limit the field of view while the conductive spacer eliminates the need to use a conductive paint on the emissive element.

An improved patch for radiative coolers

NASA Astrophysics Data System (ADS)

Bly, Vincent T.

1993-01-01

A unique structure for constructing the emissive patch of a spaceborne radiative cooler is shown. The structure has very high emissivity for all angles up to a designed-in maximum angle and near zero emissivity for greater angles. The structure also allows the use of high emissivity, nonconducting paints while fully complying with the NASA Electrostatic Discharge Susceptibility requirements for spacecraft. To accomplish these tasks, two previous disadvantages of prior art methods are addressed; eliminating background thermal radiation sources and problems concerning the high emissivity paints used in association with the black body radiator. A reflector consisting of an array of parabolic concentrators is separated from a black body element by an electrically conductive spacer. The concentrators serve to limit the field of view while the conductive spacer eliminates the need to use a conductive paint on the emissive element.

Plasma drag on a dust grain due to Coulomb collisions

NASA Technical Reports Server (NTRS)

Northrop, T. G.; Birmingham, T. J.

1990-01-01

Expressions are given for the drag due to Coulomb collisions on a charged dust grain moving through a plasma. The commonly used Chandrasekhar (1943) result does not include large scattering angles or plasma collective effects. An equation given by Morfill et al. (1980) which does include large scattering angles, is limited to one-dimensional plasma particle motion and can give at least an order of magnitude too much drag. This paper also makes use of an analogy between the drag problem and problems in electrostatics. This analogy permits generalization to any isotropic plasma of an observation made by Chandrasekhar for a Maxwellian, namely, that the drag is independent of the presence or absence of plasma particles moving faster than the grain. Finally, the contribution of plasma collective effects to the drag is studied with the inclusion of large scattering angles.

Solvent effect on the conformation of Benzil

NASA Astrophysics Data System (ADS)

Pawelka, Z.; Koll, A.; Zeegers-Huyskens, Th.

2001-10-01

The conformation of benzil is investigated by PM3 and density functional theory (B3LYP) combined with the 6-31G(d,p) basis set. The variation of the relative energy with the Odbnd C-Cdbnd O torsion angle indicates only one rather flat minimum, reflecting the flexibility of the benzil molecule. The dipole moment is measured in several organic solvents of various polarity and the IR and Raman spectra investigated in the Cdbnd O stretching region in the same solvents. The torsional Odbnd C-Cdbnd O angle is evaluated from the dipolar and vibrational data. The results indicate that, in all the solvents, benzil is in a skewed conformation, the cisoid conformation being slightly favoured when the polarity of the solvent increases. The contribution of electrostatic and specific interactions to the reduction of the torsional angle is discussed.

Electromagnetic ion/ion cyclotron instability - Theory and simulations

NASA Technical Reports Server (NTRS)

Winske, D.; Omidi, N.

1992-01-01

Linear theory and 1D and 2D hybrid simulations are employed to study electromagnetic ion/ion cyclotron (EMIIC) instability driven by the relative streaming of two field-aligned ion beams. The characteristics of the instability are studied as a function of beam density, propagation angle, electron-ion temperature ratios, and ion beta. When the propagation angle is near 90 deg the EMIIC instability has the characteristics of an electrostatic instability, while at smaller angles electromagnetic effects play a significant role as does strong beam coupling. The 2D simulations point to a narrowing of the wave spectrum and accompanying coherent effects during the linear growth stage of development. The EMIIC instability is an important effect where ion beta is low such as in the plasma-sheet boundary layer and upstream of slow shocks in the magnetotail.

Stimulated Brillouin scatter in a magnetized ionospheric plasma.

PubMed

Bernhardt, P A; Selcher, C A; Lehmberg, R H; Rodriguez, S P; Thomason, J F; Groves, K M; McCarrick, M J; Frazer, G J

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f(CI)) or an electrostatic ion cyclotron (EIC) wave just above f(CI) can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves are excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.

Numerical simulation of a radially injected barium cloud

NASA Technical Reports Server (NTRS)

Swift, D. W.; Wescott, E. M.

1981-01-01

Electrostatic two-dimensional numerical simulations of a radially symmetric barium injection experiment demonstrate that ions created by solar UV irradiation are electrostatically bound to the electrons which remain tied to the field lines on which they are created. Two possible instabilities are identified, but neither of them causes the barium plasma cloud to polarize in a way that would permit the plasma to keep up with the neutrals. In a second model, the velocity of the neutrals is allowed to be a function of the azimuthal angle. Here, a portion of the cloud does polarize in a way that allows a portion of the plasma to detach and move outward at the approximate speed of the neutrals. No rapid detachment is found when only the density of the neutrals is given an azimuthal asymmetry.

Solar Wind Strahl Broadening by Self-Generated Plasma Waves

NASA Technical Reports Server (NTRS)

Pavan, J.; Vinas, A. F.; Yoon, P. H.; Ziebell, L. F.; Gaelzer, R.

2013-01-01

This Letter reports on the results of numerical simulations which may provide a possible explanation for the strahl broadening during quiet solar conditions. The relevant processes involved in the broadening are due to kinetic quasi-linear wave-particle interaction. Making use of static analytical electron distribution in an inhomogeneous field, it is found that self-generated electrostatic waves at the plasma frequency, i.e., Langmuir waves, are capable of scattering the strahl component, resulting in energy and pitch-angle diffusion that broadens its velocity distribution significantly. The present theoretical results provide an alternative or complementary explanation to the usual whistler diffusion scenario, suggesting that self-induced electrostatic waves at the plasma frequency might play a key role in broadening the solar wind strahl during quiet solar conditions.

Electron pitch angle diffusion by electrostatic electron cyclotron harmonic waves: The origin of pancake distributions

NASA Astrophysics Data System (ADS)

Horne, Richard B.; Thorne, Richard M.

2000-03-01

It has been suggested that highly anisotropic electron pancake distributions are the result of pitch angle diffusion by electrostatic electron cyclotron harmonic (ECH) and whistler mode waves in the equatorial region. Here we present pitch angle diffusion rates for ECH wave spectra centered at different frequencies with respect to the electron gyrofrequency Ωe corresponding to spacecraft observations. The wave spectra are carefully mapped to the correct resonant electron velocities. We show that previous diffusion calculations of ECH waves at 1.5Ωe, driven by the loss cone instability, result in large diffusion rates confined to a small range of pitch angles near the loss cone and therefore cannot account for pancake distributions. However, when the wave spectrum is centered at higher frequencies in the band (>1.6Ωe), the diffusion rates become very small inside the loss cone, peak just outside, and remain large over a wide range of pitch angles up to 60° or more. When the upper hybrid resonance frequency ωUHR is several times Ωe, ECH waves excited in higher bands also contribute significantly to pitch angle diffusion outside the loss cone up to very large pitch angles. We suggest that ECH waves driven by a loss cone could form pancake distributions as they grow if the wave spectrum extends from the middle to the upper part of the first (and higher) gyroharmonic bands. Alternatively, we suggest that pancake distributions can be formed by outward propagation in a nonhomogeneous medium, so that resonant absorption occurs at higher frequencies between(n+12) and (n+1)Ωe in regions where waves are also growing locally at <=1.5Ωe. The calculated diffusion rates suggest that ECH waves with amplitudes of the order of 1 mV m-1 can form pancake distributions from an initially isotropic distribution on a timescale of a few hours. This is consistent with recent CRRES observations of ECH wave amplitudes following substorm injections near geostationary orbit and the timescales for pancake formation. Persistent but much weaker ECH waves can further intensify and maintain pancake distributions during magnetically quiet periods.

A SUBSATELLITE AREA-OF-VIEW CIRCUIT.

DTIC Science & Technology

A subsatellite circle circuit is included in the NRL experimental satellite position prediction and display equipment ( SPAD ). The circuit paints, on...center is defined by the subsatellite position, and the SPAD prediction computer uses the satellite look-cone angle (say, that of a cloud-cover camera) and...modification the circle circuit used for SPAD is applicable to any cathode-ray tube display having either electrostatic or magnetic deflection

Experimental investigation of the noise reduction of supersonic exhaust jets with fluidic inserts

NASA Astrophysics Data System (ADS)

Powers, Russell William Walter

The noise produced by the supersonic, high temperature jets that exhaust from military aircraft is becoming a hazard to naval personnel and a disturbance to communities near military bases. Methods to reduce the noise produced from these jets in a practical full-scale environment are difficult. The development and analysis of distributed nozzle blowing for the reduction of radiated noise from supersonic jets is described. Model scale experiments of jets that simulate the exhaust jets from typical low-bypass ratio military jet aircraft engines during takeoff are performed. Fluidic inserts are created that use distributed blowing in the divergent section of the nozzle to simulate mechanical, hardwall corrugations, while having the advantage of being an active control method. This research focuses on model scale experiments to better understand the fluidic insert noise reduction method. Distributed blowing within the divergent section of the military-style convergent divergent nozzle alters the shock structure of the jet in addition to creating streamwise vorticity for the reduction of mixing noise. Enhancements to the fluidic insert design have been performed along with experiments over a large number of injection parameters and core jet conditions. Primarily military-style round nozzles have been used, with preliminary measurements of hardwall corrugations and fluidic inserts in rectangular nozzle geometries also performed. It has been shown that the noise reduction of the fluidic inserts is most heavily dependent upon the momentum flux ratio between the injector and core jet. Maximum reductions of approximately 5.5 dB OASPL have been observed with practical mass flow rates and injection pressures. The first measurements with fluidic inserts in the presence of a forward flight stream have been performed. Optimal noise reduction occurs at similar injector parameters in the presence of forward flight. Fluidic inserts in the presence of a forward flight stream were observed to reduce the peak mixing noise below the already reduced levels by nearly 4 dB OASP and the broadband shock-associated noise by nearly 3 dB OASP. Unsteady velocity measurements are used to complement acoustic results of jets with fluidic inserts. Measured axial turbulence intensities and mean axial velocity are examined to illuminate the differences in the flow field from jets with fluidic inserts. Comparisons of laser Doppler measurements with RANS CFD simulations are shown with good agreement. Analysis of the effect of spatial turbulence on the measured quantities is performed. Experimental model scale measurements of jets with and without fluidic inserts over a simulated carrier deck are presented. The model carrier environment consists of a ground plane of adjustable distance below the jet, and a simulated jet blast deflector similar to those found in practice. Measurements are performed with far-field microphones, near-field microphones, and unsteady pressure sensors. The constructive and destructive interference that results from the interaction of the direct and reflected sound waves is observed and compared with results from free jets. The noise reduction of fluidic inserts in a realistic carrier deck environment with steering of the "quiet planes" is examined. The overall sound pressure level in heat-simulated jets is reduced by 3-5 dB depending on the specific angle and ground plane height. Jets impinging upon a modeled jet blast deflector are tested in addition to jets solely in the presence of the carrier deck. Observed modifications to the acoustic field from the presence of the jet blast deflector include downstream acoustic shielding and low frequency augmentation. The region of maximum noise radiation for heat-simulated jets from nozzles with fluidic inserts impinging on the jet blast deflector is reduced in overall sound pressure level by 4-7 dB. This region includes areas where aircraft carrier personnel are located. iv.

Few Ramachandran Angle Changes Provide Interaction Strength Increase in Aβ42 versus Aβ40 Amyloid Fibrils

NASA Astrophysics Data System (ADS)

Bastidas, Oscar H.; Green, Benjamin; Sprague, Mary; Peters, Michael H.

2016-11-01

The pathology of Alzheimer’s disease can ultimately be traced to the increased aggregation stability of Aβ42 peptides which possess two extra residues (Ile 41 & Ala 42) that the non-pathological strain (Aβ40) lacks. We have found Aβ42 fibrils to exhibit stronger energies in inter-chain interactions and we have also identified the cause for this increase to be the result of different Ramachandran angle values in certain residues of the Aβ42 strain compared to Aβ40. These unique angle configurations result in the peptide planes in the fibril structures to be more vertical along the fibril axis for Aβ42 which thus reduces the inter-atomic distance between interacting atoms on vicinal peptide chains thereby increasing the electrostatic interaction energies. We lastly postulate that these different Ramachandran angle values could possibly be traced to the unique conformational folding avenues sampled by the Aβ42 peptide owing to the presence of its two extra residues.

A Wide Field of View Plasma Spectrometer

DOE PAGES

Skoug, Ruth M.; Funsten, Herbert O.; Moebius, Eberhard; ...

2016-07-01

Here we present a fundamentally new type of space plasma spectrometer, the wide field of view plasma spectrometer, whose field of view is >1.25π ster using fewer resources than traditional methods. The enabling component is analogous to a pinhole camera with an electrostatic energy-angle filter at the image plane. Particle energy-per-charge is selected with a tunable bias voltage applied to the filter plate relative to the pinhole aperture plate. For a given bias voltage, charged particles from different directions are focused by different angles to different locations. Particles with appropriate locations and angles can transit the filter plate and aremore » measured using a microchannel plate detector with a position-sensitive anode. Full energy and angle coverage are obtained using a single high-voltage power supply, resulting in considerable resource savings and allowing measurements at fast timescales. Lastly, we present laboratory prototype measurements and simulations demonstrating the instrument concept and discuss optimizations of the instrument design for application to space measurements.« less

76 FR 52639 - New England Fishery Management Council; Public Meeting

Federal Register 2010, 2011, 2012, 2013, 2014

2011-08-23

... alternatives related to four specific issues: (1) Potentially require a turtle deflector dredge for scallop dredge vessels; (2) revise the yellowtail flounder accountability measures (AMs) proposed in Amendment 15...

High Pressure Industrial Water Facility

NASA Technical Reports Server (NTRS)

1992-01-01

In conjunction with Space Shuttle Main Engine testing at Stennis, the Nordberg Water Pumps at the High Pressure Industrial Water Facility provide water for cooling the flame deflectors at the test stands during test firings.

Point mass deflectors in gravitational lenses

NASA Technical Reports Server (NTRS)

Dolan, Joseph F.

1988-01-01

The observed properties of the six systems generally accepted as gravitational lenses are compared with the properties predicted for the images of point-mass and distributed mass deflectors. Taken as a statistical distribution, the characteristics of the six known systems strongly suggest the existence of a super-massive black hole as the effective deflecting mass in one or more of these systems. If the deflecting mass in a gravitational lens is a black hole, the distance to the deflecting mass can be determined directly from the difference in light travel time along the separate image paths. (No direct solution for the distance to the deflecting mass exists when the deflecting mass is a galaxy or a cluster of galaxies). Geometric parallaxes of objects at 1000 Mpc distance are of obvious importance in a wide variety of cosmological studies.

Optical circular deflector with attosecond resolution for ultrashort electron beam

DOE PAGES

Zhang, Zhen; Du, Yingchao; Tang, Chuanxiang; ...

2017-05-25

A novel method using high-power laser as a circular deflector is proposed for the measurement of femtosecond (fs) and sub-fs electron beam. In the scheme, the electron beam interacts with a laser pulse operating in a radially polarized doughnut mode ( TEM 01 * ) in a helical undulator, generating angular kicks along the beam in two directions at the same time. The phase difference between the two angular kicks makes the beam form a ring after a propagation section with appropriate phase advance, which can reveal the current profile of the electron beam. Detailed theoretical analysis of the methodmore » and numerical results with reasonable parameters are both presented. Lastly, it is shown that the temporal resolution can reach up to ~ 100 attosecond, which is a significant improvement for the diagnostics of ultrashort electron beam.« less

Optical circular deflector with attosecond resolution for ultrashort electron beam

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

Zhang, Zhen; Du, Yingchao; Tang, Chuanxiang

A novel method using high-power laser as a circular deflector is proposed for the measurement of femtosecond (fs) and sub-fs electron beam. In the scheme, the electron beam interacts with a laser pulse operating in a radially polarized doughnut mode ( TEM 01 * ) in a helical undulator, generating angular kicks along the beam in two directions at the same time. The phase difference between the two angular kicks makes the beam form a ring after a propagation section with appropriate phase advance, which can reveal the current profile of the electron beam. Detailed theoretical analysis of the methodmore » and numerical results with reasonable parameters are both presented. Lastly, it is shown that the temporal resolution can reach up to ~ 100 attosecond, which is a significant improvement for the diagnostics of ultrashort electron beam.« less

Supported PV module assembly

DOEpatents

Mascolo, Gianluigi; Taggart, David F.; Botkin, Jonathan D.; Edgett, Christopher S.

2013-10-15

A supported PV assembly may include a PV module comprising a PV panel and PV module supports including module supports having a support surface supporting the module, a module registration member engaging the PV module to properly position the PV module on the module support, and a mounting element. In some embodiments the PV module registration members engage only the external surfaces of the PV modules at the corners. In some embodiments the assembly includes a wind deflector with ballast secured to a least one of the PV module supports and the wind deflector. An array of the assemblies can be secured to one another at their corners to prevent horizontal separation of the adjacent corners while permitting the PV modules to flex relative to one another so to permit the array of PV modules to follow a contour of the support surface.

Linear time-to-space mapping system using double electrooptic beam deflectors.

PubMed

Hisatake, Shintaro; Tada, Keiji; Nagatsuma, Tadao

2008-12-22

We propose and demonstrate a linear time-to-space mapping system, which is based on two times electrooptic sinusoidal beam deflection. The direction of each deflection is set to be mutually orthogonal with the relative deflection phase of pi/2 rad so that the circular optical beam trajectory can be achieved. The beam spot at the observation plane moves with an uniform velocity and as a result linear time-to-space mapping (an uniform temporal resolution through the mapping) can be realized. The proof-of-concept experiment are carried out and the temporal resolution of 5 ps has been demonstrated using traveling-wave type quasi-velosity-matched electrooptic beam deflectors. The developed system is expected to be applied to characterization of ultrafast optical signal or optical arbitrary waveform shaping for modulated microwave/millimeter-wave generation.

Post STS-133 Evaluation of Main Flame Deflector Witness Materials

NASA Technical Reports Server (NTRS)

Long, Victoria

2011-01-01

NASA and USA Structures engineers submitted main flame deflector witness materials for evaluation after the launch of STS-133. The following items were submitted for analysis: HY-80 steel witness rods, 304 stainless steel caps, tungsten pistons, 17-4 precipitation hardened (PH) stainless steel and A-286 piston sleeves, Medtherm Corporation calorimeters, and Nanmac Corporation thermocouples. All of the items were photographed in order to document their condition after the launch of STS-133, and before they were reinstalled at the launch pad for future launches. The HY -80 witness rods, 304 stainless steel caps, and the piston sleeves were dimensionally measured in order to determine the amount of material lost during launch. Microstructural changes were observed in the HY-80 witness rod and 304 stainless steel cap metallographic samples due to the heat of the launch.

Optimization and Modeling of Noise Reduction for Turbulent Jets with Induced Asymmetry

NASA Astrophysics Data System (ADS)

Rostamimonjezi, Sara

This project relates to the development of next-generation high-speed aircraft that are efficient and environmentally compliant. The emphasis of the research is on reducing noise from high-performance engines that will power these aircraft. A strong component of engine noise is jet mixing noise that comes from the turbulent mixing process between the high-speed exhaust flow of the engine and the atmosphere. The fan flow deflection method (FFD) suppresses jet noise by deflecting the fan stream downward, by a few degrees, with respect to the core stream. This reduces the convective Mach number of the primary shear layer and turbulent kinetic energy in the downward direction and therefore reduces the noise emitted towards the ground. The redistribution of the fan stream is achieved with inserting airfoil-shaped vanes inside the fan duct. Aerodynamic optimization of FFD has been done by Dr. Juntao Xiong using a computational fluid dynamics code to maximize reduction of noise perceived by the community while minimizing aerodynamic losses. The optimal vane airfoils are used in a parametric experimental study of 50 4-vane deflector configurations. The vane chord length, angle of attack, and azimuthal location are the parameters studied in acoustic optimization. The best vane configuration yields a reduction in cumulative (downward + sideline) effective perceived noise level (EPNL) of 5.3 dB. The optimization study underscores the sensitivity of FFD to deflector parameters and the need for careful design in the practical implementation of this noise reduction approach. An analytical model based on Reynolds Averaged Navier Stokes (RANS) and acoustic analogy is developed to predict the spectral changes from a known baseline in the direction of peak emission. A generalized form for space-time correlation is introduced that allows shapes beyond the traditional exponential forms. Azimuthal directivity based on the wavepacket model of jet noise is integrated with the acoustic analogy model. A physics-based definition of convective Mach number is proposed. The predicted noise reduction is in reasonable agreement with the experiments. The study underscores the importance of a proper definition of convective Mach number when modeling noise in the direction of peak emission.

Charged patchy particle models in explicit salt: Ion distributions, electrostatic potentials, and effective interactions.

PubMed

Yigit, Cemil; Heyda, Jan; Dzubiella, Joachim

2015-08-14

We introduce a set of charged patchy particle models (CPPMs) in order to systematically study the influence of electrostatic charge patchiness and multipolarity on macromolecular interactions by means of implicit-solvent, explicit-ion Langevin dynamics simulations employing the Gromacs software. We consider well-defined zero-, one-, and two-patched spherical globules each of the same net charge and (nanometer) size which are composed of discrete atoms. The studied mono- and multipole moments of the CPPMs are comparable to those of globular proteins with similar size. We first characterize ion distributions and electrostatic potentials around a single CPPM. Although angle-resolved radial distribution functions reveal the expected local accumulation and depletion of counter- and co-ions around the patches, respectively, the orientation-averaged electrostatic potential shows only a small variation among the various CPPMs due to space charge cancellations. Furthermore, we study the orientation-averaged potential of mean force (PMF), the number of accumulated ions on the patches, as well as the CPPM orientations along the center-to-center distance of a pair of CPPMs. We compare the PMFs to the classical Derjaguin-Verwey-Landau-Overbeek theory and previously introduced orientation-averaged Debye-Hückel pair potentials including dipolar interactions. Our simulations confirm the adequacy of the theories in their respective regimes of validity, while low salt concentrations and large multipolar interactions remain a challenge for tractable theoretical descriptions.

Generalized Stability Conditions for an Ultra-Low Energy Electrostatic Charged Particle Storage Ring

NASA Astrophysics Data System (ADS)

Sullivan, Michael

A low energy (~50 eV) electrostatic storage ring has been constructed that can store a recirculating bunch of either electrons or ions. The charged particle bunch 'orbits' within an apparatus consisting of four lenses and two hemispherical deflector analysers, arranged in a 'race-track' configuration of length 64.1 cm. A theoretical study, using transfer matrices from charged particle optics for a 'symmetric' configuration of lens potentials, has been previously completed by Hammond et al. [New J. Phys. 11 (2009) 043033]. That approach was capable of predicting modes of storage which appeared as a resonant-like pattern. An 'asymmetric' configuration, new in this work and extending the previous study to apply to a more general case, has been completed and will be presented alongside experimental results. The level of agreement between the theoretical and experimental results is found to be excellent, and the robustness of the matrix formalism has eliminated the need to rely on computer simulation to achieve storage. This asymmetric arrangement of the lenses allows for greater flexibility in the operation of the ring, creating the potential for a more diverse range of applications and potentially aid in the design of future rings. Several spectra for both electrons and positive ions are presented to provide an indication as to how the charged particle bunch evolves as more orbits are completed. The number of counts inevitably decreases as a function of orbit number due to loss mechanisms. Enhanced measurement techniques, as well as the matrix theory, have made storage of the bunch for over a hundred orbits routine, corresponding to over 65 m travelled, and this is observed directly from the spectra. The application of the storage ring as a multi-pass time-of-flight mass spectrometer has been studied. The isotopes of krypton and xenon have been made to completely separate from one another out of a single pulse of ions. This is observed to occur after ~15 orbits of the ring, roughly 10 m of distance. Initial results have indicated that the mass resolution is approximately 5000. Limitations and potential improvements to the mass resolution are presented.

Contact angle hysteresis and oil film lubrication in electrowetting with two immiscible liquids

NASA Astrophysics Data System (ADS)

Gao, J.; Mendel, N.; Dey, R.; Baratian, D.; Mugele, F.

2018-05-01

Electrowetting (EW) of water drops in ambient oil has found a wide range of applications including lab-on-a-chip devices, display screens, and variable focus lenses. The efficacy of all these applications is dependent on the contact angle hysteresis (CAH), which is generally reduced in the presence of ambient oil due to thin lubrication layers. While it is well-known that AC voltage reduces the effective contact angle hysteresis (CAH) for EW in ambient air, we demonstrate here that CAH for EW in ambient oil increases with increasing AC and DC voltage. Taking into account the disjoining pressure of the fluoropolymer-oil-water system, short range chemical interactions, viscous oil entrainment, and electrostatic stresses, we find that this observation can be explained by progressive thinning of the oil layer underneath the drop with increasing voltage. This exposes the droplet to the roughness of the underlying solid and thereby increases hysteresis.

Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization.

PubMed

Wang, K F; Wang, B L

2018-06-22

Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30°, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable.

Electrostatic potential in a bent piezoelectric nanowire with consideration of size-dependent piezoelectricity and semiconducting characterization

NASA Astrophysics Data System (ADS)

Wang, K. F.; Wang, B. L.

2018-06-01

Determining the electric potential in a bent piezoelectric nanowire (NW) is a fundamental issue of nanogenerators and nanopiezotronics. The combined influence of the flexoelectric effect, the semiconducting performance and the angle of atomic force microscope (AFM) tip has never been studied previously and will be investigated in this paper. The exact solution for the electric potential of a bent piezoelectric semiconductor NW is derived. The electric potential of the present model with consideration of flexoelectric effect varies along the length of the NW and is different from that of the classical piezoelectric model. Flexoelectric effect enhances but the semiconducting performance reduces the electric potential of the NW. In addition, it is found that if the angle of the AFM tip reaches 30°, the error of the electric potential obtained from the model ignored the effect of the angle of the AFM tip is almost 16%, which is unacceptable.

Stimulated Brillouin Scatter in a Magnetized Ionospheric Plasma

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

Bernhardt, P. A.; Selcher, C. A.; Lehmberg, R. H.

2010-04-23

High power electromagnetic waves transmitted from the HAARP facility in Alaska can excite low-frequency electrostatic waves by magnetized stimulated Brillouin scatter. Either an ion-acoustic wave with a frequency less than the ion cyclotron frequency (f{sub CI}) or an electrostatic ion cyclotron (EIC) wave just above f{sub CI} can be produced. The coupled equations describing the magnetized stimulated Brillouin scatter instability show that the production of both ion-acoustic and EIC waves is strongly influenced by the wave propagation relative to the background magnetic field. Experimental observations of stimulated electromagnetic emissions using the HAARP transmitter have confirmed that only ion-acoustic waves aremore » excited for propagation along the magnetic zenith and that EIC waves can only be detected with oblique propagation angles. The ion composition can be obtained from the measured EIC frequency.« less

Tuning structure of oppositely charged nanoparticle and protein complexes

NASA Astrophysics Data System (ADS)

Kumar, Sugam; Aswal, V. K.; Callow, P.

2014-04-01

Small-angle neutron scattering (SANS) has been used to probe the structures of anionic silica nanoparticles (LS30) and cationic lyszyme protein (M.W. 14.7kD, I.P. ˜ 11.4) by tuning their interaction through the pH variation. The protein adsorption on nanoparticles is found to be increasing with pH and determined by the electrostatic attraction between two components as well as repulsion between protein molecules. We show the strong electrostatic attraction between nanoparticles and protein molecules leads to protein-mediated aggregation of nanoparticles which are characterized by fractal structures. At pH 5, the protein adsorption gives rise to nanoparticle aggregation having surface fractal morphology with close packing of nanoparticles. The surface fractals transform to open structures of mass fractal morphology at higher pH (7 and 9) on approaching isoelectric point (I.P.).

Time-of-flight mass spectrographs—From ions to neutral atoms

NASA Astrophysics Data System (ADS)

Möbius, E.; Galvin, A. B.; Kistler, L. M.; Kucharek, H.; Popecki, M. A.

2016-12-01

After their introduction to space physics in the mid 1980s time-of-flight (TOF) spectrographs have become a main staple in spaceborne mass spectrometry. They have largely replaced magnetic spectrometers, except when extremely high mass resolution is required to identify complex molecules, for example, in the vicinity of comets or in planetary atmospheres. In combination with electrostatic analyzers and often solid state detectors, TOF spectrographs have become key instruments to diagnose space plasma velocity distributions, mass, and ionic charge composition. With a variety of implementation schemes that also include isochronous electric field configurations, TOF spectrographs can respond to diverse science requirements. This includes a wide range in mass resolution to allow the separation of medium heavy isotopes or to simply provide distributions of the major species, such as H, He, and O, to obtain information on source tracers or mass fluxes. With a top-hat analyzer at the front end, or in combination with deflectors for three-axis stabilized spacecraft, the distribution function of ions can be obtained with good time resolution. Most recently, the reach of TOF ion mass spectrographs has been extended to include energetic neutral atoms. After selecting the arrival direction with mechanical collimation, followed by conversion to ions, adapted TOF sensors form a new branch of the spectrograph family tree. We review the requirements, challenges, and implementation schemes for ion and neutral atom spectrographs, including potential directions for the future, while largely avoiding overlap with complementary contributions in this special issue.

The center for production of single-photon emitters at the electrostatic-deflector line of the Tandem accelerator of LABEC (Florence)

NASA Astrophysics Data System (ADS)

Lagomarsino, Stefano; Sciortino, Silvio; Gelli, Nicla; Flatae, Assegid M.; Gorelli, Federico; Santoro, Mario; Chiari, Massimo; Czelusniac, Caroline; Massi, Mirko; Taccetti, Francesco; Agio, Mario; Giuntini, Lorenzo

2018-05-01

The line for the pulsed beam of the 3 MeV Tandetron accelerator at LABEC (Florence) has been upgraded for ion implantation experiments aiming at the fabrication of single-photon emitters in a solid-state matrix. A system based on Al attenuators has been calibrated in order to extend the energy range of the implanted ions from MeV down to the tens of keV. A new motorized XY stage has been installed in the implantation chamber for achieving ultra-fine control on the position of each implanted ion, allowing to reach the scale imposed by lateral straggling. A set-up for the activation of the implanted ions has been developed, based on an annealing furnace operating under controlled high-vacuum conditions. The first experiments have been performed with silicon ions implanted in diamond and the luminescent signal of the silicon-vacancy (SiV) center, peaked at 738 nm, has been observed for a wide range of implantation fluences (108 ÷ 1015 cm-2) and implantation depths (from a few nm to 2.4 μm). Studies on the efficiency of the annealing process have been performed and the activation yield has been measured to range from 1% to 3%. The implantation and annealing facility has thus been tuned for the production of SiV centers in diamond, but is in principle suitable for other ion species and solid-state matrices.

75 FR 5618 - Notice of Issuance of Final Determination Concerning a Certain Alternator

Federal Register 2010, 2011, 2012, 2013, 2014

2010-02-03

... meter to measure the rotor resistance; a hi-pot test to check insulation between each phase to ground... air flow deflector; installing the rectifier sub-assembly; installing the heat shrink tubing; and...

Low-speed wind tunnel investigation of a semispan STOL jet transport wing body with an upper surface blown jet flap

NASA Technical Reports Server (NTRS)

Phelps, A. E., III; Letko, W.; Henderson, R. L.

1973-01-01

An investigation of the static longitudinal aerodynamic characteristics of a semispan STOL jet transport wing-body with an upper-surface blown jet flap for lift augmentation was conducted in a low-speed wind tunnel having a 12-ft octagonal test section. The semispan swept wing had an aspect ratio of 3.92 (7.84 for the full span) and had two simulated turbofan engines mounted ahead of and above the wing in a siamese pod equipped with an exhaust deflector. The purpose of the deflector was to spread the engine exhaust into a jet sheet attached to the upper surface of the wing so that it would turn downward over the flap and provide lift augmentation. The wing also had optional boundary-layer control provided by air blowing through a thin slot over a full-span plain trailing-edge flap.

Rapid Optical Shutter, Chopper, Modulator and Deflector

NASA Technical Reports Server (NTRS)

Danehy, Paul M. (Inventor)

2017-01-01

An optical device with a light source and a detector is provided. A digital micromirror device positioned between the detector and the light source may deflect light beams projected from the light source. An aperture in front of the detector may block an incoming light beam from the detector when the incoming light beam is incident on the detector outside of a passable incident range and including an aperture opening configured to pass the incoming light beam to the detector when the incoming light beam is incident on the detector within a passable incident range. The digital micromirror device may rotate between a first position causing the light beam to pass through the aperture opening and a second position causing the light beam to be blocked by the aperture. The optical device may be configured to operate as a shutter, chopper, modulator and/or deflector.

Pseudomorphic In(y)Ga(1-y)As/GaAs/Al(x)Ga(1-x)As single quantum well surface-emitting lasers with integrated 45 deg beam deflectors

NASA Technical Reports Server (NTRS)

Kim, Jae-Hoon; Larsson, Anders; Lee, Luke P.

1991-01-01

The paper reports on the first demonstration of pseudomorphic InGaAs single quantum well surface-emitting lasers (SELs), with etched vertical mirrors and integrated 45-deg beam deflectors fabricated by ion beam etching. 100-micron-wide broad-area SELs exhibited a threshold current of 320 mA, a total power of 126 mW, and a total external differential quantum efficiency of 0.09 W/A for a 500-micron-long cavity. The perpendicular far-field pattern of broad-area SELs showed a full width at half maximum of about 20 deg. Lasers with various types of cavities fabricated from the same wafer were compared. Broad-area edge-emitting lasers had a threshold current of 200 mA, a total power of 700 mW, and a total external differential quantum efficiency of 0.52 W/A.

Formation of a quasi-hollow beam of high-energy heavy ions using a multicell resonance RF deflector

NASA Astrophysics Data System (ADS)

Minaev, S. A.; Sitnikov, A. L.; Golubev, A. A.; Kulevoy, T. V.

2012-09-01

The generation of matter in an extreme state with precisely measurable parameters is of great interest for contemporary physics. One way of obtaining such a state is to irradiate the end of a hollow cylindrical shell at the center of which a test material is kept at a temperature of several Kelvin by an annular beam of high-energy heavy ions. Under the action of the beam, the shell starts explosively expanding both outwards and inwards, compressing the material to an extremely high pressure without subjecting it to direct heating. A method of producing a hollow cylindrical beam of high-energy heavy ions using a resonance rf deflector is described. The deflection of the beam in two transverse directions by means of an rf electric field allows it to rotate about the longitudinal axis and irradiate an annular domain on the end face of the target.

Improving time-delay cosmography with spatially resolved kinematics

NASA Astrophysics Data System (ADS)

Shajib, Anowar J.; Treu, Tommaso; Agnello, Adriano

2018-01-01

Strongly gravitational lensed quasars can be used to measure the so-called time-delay distance DΔt, and thus the Hubble constant H0 and other cosmological parameters. Stellar kinematics of the deflector galaxy play an essential role in this measurement by: (i) helping break the mass-sheet degeneracy; (ii) determining in principle the angular diameter distance Dd to the deflector and thus further improving the cosmological constraints. In this paper we simulate observations of lensed quasars with integral field spectrographs and show that spatially resolved kinematics of the deflector enables further progress by helping break the mass-anisotropy degeneracy. Furthermore, we use our simulations to obtain realistic error estimates with current/upcoming instruments like OSIRIS on Keck and NIRSPEC on the James Webb Space Telescope for both distances (typically ∼6 per cent on DΔt and ∼10 per cent on Dd). We use the error estimates to compute cosmological forecasts for the sample of nine lenses that currently have well-measured time delays and deep Hubble Space Telescope images and for a sample of 40 lenses that is projected to be available in a few years through follow-up of candidates found in ongoing wide field surveys. We find that H0 can be measured with 2 per cent (1 per cent) precision from nine (40) lenses in a flat Λcold dark matter cosmology. We study several other cosmological models beyond the flat Λcold dark matter model and find that time-delay lenses with spatially resolved kinematics can greatly improve the precision of the cosmological parameters measured by cosmic microwave background data.

Ricochet pollination in Senna (Fabaceae) - petals deflect pollen jets and promote division of labour among flower structures.

PubMed

Amorim, T; Marazzi, B; Soares, A A; Forni-Martins, E R; Muniz, C R; Westerkamp, C

2017-11-01

Naturalists Fritz and Hermann Müller hypothesised that heteranthery often leads to a division of labour into 'feeding' and 'pollinating' stamens; the latter often being as long as the pistil so as to promote successful pollination on the bees' back. In many buzz-pollinated species of Senna, however, the so-called pollinating stamens are short and not level with the stigma, raising the question of how pollen is shed on the bees' back. Here we explore a mechanism called 'ricochet pollination'. We test whether division of labour is achieved through the interaction between short lower stamens and strongly concave 'deflector petals'. We studied the arrangement and morphology of the floral organs involved in the ricochet pollination, functioning of the flowers through artificial sonication and observed the interactions between bees and flowers in the field. The middle stamens are adapted to eject pollen downwards, which can be readily collected on the bee mid legs. Most of the pollen is ejected towards the deflector petal(s). Pollen from this set of stamens is more likely to contribute to pollination. The pollen grains seem to ricochet multiple times against the deflector petals to eventually reach the bee's back. The pollen ricochet mechanism promotes a division of labour by involving additional floral organs, such as petals, reinforcing the Müllers' division-of-labour hypothesis. However, alternative, non-multiexclusive hypotheses could be explored in genus Senna and other angiosperm species. © 2017 German Society for Plant Sciences and The Royal Botanical Society of the Netherlands.

Modified interactions among globular proteins below isoelectric point in the presence of mono-, di- and tri-valent ions: A small angle neutron scattering study

NASA Astrophysics Data System (ADS)

Das, Kaushik; Kundu, Sarathi; Mehan, Sumit; Aswal, V. K.

2016-02-01

Both short range attraction and long range electrostatic repulsion exist among globular protein Bovine Serum Albumin in solution below its isoelectric point (pI ≈ 4.8). At pD ≈ 4.0, below pI, protein has a net positive surface charge although local charge inhomogeneity presents. Small angle neutron scattering study reveals that in the presence of both mono-(Na+) and di-(Ni2+) valent ions attractive interaction increases and repulsive interaction decreases with the increase of salt concentration. However, for tri-valent (Fe3+) ions, both attractive and repulsive interaction increases with increasing salt concentration but the relative strength of repulsion is more than the attraction.

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

N, Rekha T.; Rajkumar, Beulah J. M., E-mail: beulah-rajkumar@yahoo.co.in

Charge transfer properties of pentacene adsorbed on silver is investigated using DFT methods. Optimized geometry of pentacene after adsorption on silver indicates distortion in hexagonal structure of the ring close to the silver cluster and deviations in co-planarity of carbon atoms due to the variations in bond angles and dihedral angles. Theoretically simulated absorption spectrum has a symmetric surface plasmon resonance peak around 486nm corresponding to the transfer of charge from HOMO-2 to LUMO. Theoretical SERS confirms the process of adsorption, tilted orientation of pentacene on silver surface and the charge transfers reported. Localization of electron density arising from redistributionmore » of electrostatic potential together with a reduced bandgap of pentacene after adsorption on silver suggests its utility in the design of electro active organic semiconducting devices.« less

The Deflector Selector: A Machine Learning Framework for Prioritizing Deflection Technology Development

NASA Astrophysics Data System (ADS)

Nesvold, E. R.; Erasmus, N.; Greenberg, A.; van Heerden, E.; Galache, J. L.; Dahlstrom, E.; Marchis, F.

2017-02-01

We present a machine learning model that can predict which asteroid deflection technology would be most effective, given the likely population of impactors. Our model can help policy and funding agencies prioritize technology development.

28. Credit JTL. Overview of unit 5 (installed 1908) showing ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

28. Credit JTL. Overview of unit 5 (installed 1908) showing exciter, generator, deflector motor, needle valve control, impulse wheel housing, and gate valve controls. - Battle Creek Hydroelectric System, Battle Creek & Tributaries, Red Bluff, Tehama County, CA

Asymptotic solutions for the case of nearly symmetric gravitational lens systems

NASA Astrophysics Data System (ADS)

Wertz, O.; Pelgrims, V.; Surdej, J.

2012-08-01

Gravitational lensing provides a powerful tool to determine the Hubble parameter H0 from the measurement of the time delay Δt between two lensed images of a background variable source. Nevertheless, knowledge of the deflector mass distribution constitutes a hurdle. We propose in the present work interesting solutions for the case of nearly symmetric gravitational lens systems. For the case of a small misalignment between the source, the deflector and the observer, we first consider power-law (ɛ) axially symmetric models for which we derive an analytical relation between the amplification ratio and source position which is independent of the power-law slope ɛ. According to this relation, we deduce an expression for H0 also irrespective of the value ɛ. Secondly, we consider the power-law axially symmetric lens models with an external large-scale gravitational field, the shear γ, resulting in the so-called ɛ-γ models, for which we deduce simple first-order equations linking the model parameters and the lensed image positions, the latter being observable quantities. We also deduce simple relations between H0 and observables quantities only. From these equations, we may estimate the value of the Hubble parameter in a robust way. Nevertheless, comparison between the ɛ-γ and singular isothermal ellipsoid (SIE) models leads to the conclusion that these models remain most often distinct. Therefore, even for the case of a small misalignment, use of the first-order equations and precise astrometric measurements of the positions of the lensed images with respect to the centre of the deflector enables one to discriminate between these two families of models. Finally, we confront the models with numerical simulations to evaluate the intrinsic error of the first-order expressions used when deriving the model parameters under the assumption of a quasi-alignment between the source, the deflector and the observer. From these same simulations, we estimate for the case of the ɛ-γ family of models that the standard deviation affecting H0 is ? which merely reflects the adopted astrometric uncertainties on the relative image positions, typically ? arcsec. In conclusions, we stress the importance of getting very accurate measurements of the relative positions of the multiple lensed images and of the time delays for the case of nearly symmetric gravitational lens systems, in order to derive robust and precise values of the Hubble parameter.

VLF Transmitter Signal Power Loss to Quasi-Electrostatic Whistler Mode Waves in Regions Containing Plasma Density Irregularities

NASA Astrophysics Data System (ADS)

Bell, T. F.; Foust, F.; Inan, U. S.; Lehtinen, N. G.

2010-12-01

The energetic particles comprising the Earth’s radiation belts are an important component of Space Weather. The commonly accepted model of the quasi-steady radiation belts developed by Abel and Thorne [1998] proposes that VLF signals from powerful ground based transmitters determine the lifetimes of energetic radiation belt electrons (100 keV-1.5 MeV) on L shells in the range 1.3-2.8. The primary mechanism of interaction is pitch angle scattering during gyro-resonance. Recent observations [Starks et al., 2008] from multiple spacecraft suggest that the actual night time intensity of VLF transmitter signals in the radiation belts is approximately 20 dB below the level assumed in the Abel and Thorne model and approximately 10 dB below model values during the day. In this work we discuss one mechanism which might be responsible for a large portion of this intensity discrepancy. The mechanism is linear mode coupling between electromagnetic whistler mode waves and quasi-electrostatic whistler mode waves. As VLF electromagnetic whistler mode waves propagate through regions containing small scale (2-100 m) magnetic-field-aligned plasma density irregularities, they excite quasi-electrostatic whistler mode waves, and this excitation represents a power loss for the input waves. We construct plausible models of the irregularities in order to use numerical simulations to determine the characteristics of the mode coupling mechanism and the conditions under which the input VLF waves can lose significant power to the excited quasi-electrostatic whistler mode waves.

Correcting PSP electron measurements for the effects of spacecraft electrostatic and magnetic fields

NASA Astrophysics Data System (ADS)

McGinnis, D.; Halekas, J. S.; Larson, D. E.; Whittlesey, P. L.; Kasper, J. C.

2017-12-01

The near-Sun environment which the Parker Solar Probe will investigate presents a unique challenge for the measurement of thermal and suprathermal electrons. Over one orbital period, the ionizing photon flux and charged particle densities vary to such an extent that the spacecraft could charge to electrostatic potentials ranging from a few volts to tens of volts or more, and it may even develop negative electrostatic potentials near closest approach. In addition, significant permanent magnetic fields from spacecraft components will perturb thermal electron trajectories. Given these effects, electron distribution function (EDF) measurements made by the SWEAP/SPAN electron sensors will be significantly affected. It is thus important to try to understand the extent and nature of such effects, and to remediate them as much as possible. To this end, we have incorporated magnetic fields and a model electrostatic potential field into particle tracing simulations to predict particle trajectories through the near spacecraft environment. These simulations allow us to estimate how the solid angle elements measured by SPAN deflect and stretch in the presence of these fields and therefore how and to what extent EDF measurements will be distorted. In this work, we demonstrate how this technique can be used to produce a `dewarping' correction factor. Further, we show that this factor can correct synthetic datasets simulating the warped EDFs that the SPAN instruments are likely to measure over a wide range of spacecraft potentials and plasma Debye lengths.

Atomic Forces for Geometry-Dependent Point Multipole and Gaussian Multipole Models

PubMed Central

Elking, Dennis M.; Perera, Lalith; Duke, Robert; Darden, Thomas; Pedersen, Lee G.

2010-01-01

In standard treatments of atomic multipole models, interaction energies, total molecular forces, and total molecular torques are given for multipolar interactions between rigid molecules. However, if the molecules are assumed to be flexible, two additional multipolar atomic forces arise due to 1) the transfer of torque between neighboring atoms, and 2) the dependence of multipole moment on internal geometry (bond lengths, bond angles, etc.) for geometry-dependent multipole models. In the current study, atomic force expressions for geometry-dependent multipoles are presented for use in simulations of flexible molecules. The atomic forces are derived by first proposing a new general expression for Wigner function derivatives ∂Dlm′m/∂Ω. The force equations can be applied to electrostatic models based on atomic point multipoles or Gaussian multipole charge density. Hydrogen bonded dimers are used to test the inter-molecular electrostatic energies and atomic forces calculated by geometry-dependent multipoles fit to the ab initio electrostatic potential (ESP). The electrostatic energies and forces are compared to their reference ab initio values. It is shown that both static and geometry-dependent multipole models are able to reproduce total molecular forces and torques with respect to ab initio, while geometry-dependent multipoles are needed to reproduce ab initio atomic forces. The expressions for atomic force can be used in simulations of flexible molecules with atomic multipoles. In addition, the results presented in this work should lead to further development of next generation force fields composed of geometry-dependent multipole models. PMID:20839297

Metal-ligand bond directionality in the M2-NH3 complexes (M = Cu, Ag and Au)

NASA Astrophysics Data System (ADS)

Eskandari, K.; Ebadinejad, F.

2018-05-01

The metal-ligand bonds in the M2-NH3 complexes (M = Au, Ag and Cu) are directional and the M-M-N angles tend to be linear. Natural energy decomposition analysis (NEDA) and localised molecular orbital energy decomposition analysis (LMOEDA) approaches indicate that the metal-ligand bonds in these complexes are mainly electrostatic in nature, however, the electrostatic is not the cause of the linearity of M-M-N arrangements. Instead, NEDA shows that the charge transfer and core repulsion are mainly responsible for the directionality of these bonds. In the LMOEDA point of view, the repulsion term is the main reason for the linearity of these complexes. Interacting quantum atoms (IQA) analysis shows that inter-atomic and inter-fragment interactions favour the nonlinear arrangements; however, these terms are compensated by the atomic self-energies, which stabilise the linear structure.

Technique for enhancing the power output of an electrostatic generator employing parametric resonance

DOEpatents

Post, Richard F.

2016-02-23

A circuit-based technique enhances the power output of electrostatic generators employing an array of axially oriented rods or tubes or azimuthal corrugated metal surfaces for their electrodes. During generator operation, the peak voltage across the electrodes occurs at an azimuthal position that is intermediate between the position of minimum gap and maximum gap. If this position is also close to the azimuthal angle where the rate of change of capacity is a maximum, then the highest rf power output possible for a given maximum allowable voltage at the minimum gap can be attained. This rf power output is then coupled to the generator load through a coupling condenser that prevents suppression of the dc charging potential by conduction through the load. Optimized circuit values produce phase shifts in the rf output voltage that allow higher power output to occur at the same voltage limit at the minimum gap position.

Viscoelasticity of nano-alumina dispersions

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

Rand, B.; Fries, R.

1996-06-01

The flow and viscoelastic properties of electrostatically stabilized nano-alumina dispersions have been studied as a function of ionic strength and volume fraction of solids. At low ionic strength the suspensions were deflocculated and showed a transition from viscous to elastic behavior as the solid content increased associated with the onset of double layer interpenetration. The phase transition was progressively shifted to higher solids fractions with increasing ionic strength. At higher ionic strength, above the critical coagulation concentration, the suspensions formed attractive networks characterized by high elasticity. Two independent methods of estimating the effective radius of electrostatically stabilized {open_quotes}soft{close_quotes} particles, a{submore » eff}, are presented based on phase angle data and a modified Dougherty-Krieger equation. The results suggest that a{sub eff} is not constant for a given system but changes with both solids fraction and ionic strength.« less

Electrostatic powder spraying process for the fabrication of stable superhydrophobic surfaces

NASA Astrophysics Data System (ADS)

Gu, Guotuan; Tian, Yuping; Li, Zhantie; Lu, Dongfang

2011-03-01

Nano-sized Al2O3 particles were modified by heptadecafluorodecyl trimethoxysilane and 2,3-epoxy propoxy propyl trimethoxysilicane to make it both hydrophobic and reactive. The reactive nano-particles were mixed with polyester resin containing curing agents and electrostatic sprayed on stainless steel substrates to obtain stable superhydrophobic coatings after curing. The water contact angle (WCA) on the hybrid coating is influenced by the content of Al2O3 particles in the coating. As the Al2O3 concentration in the coating was increased from 0% to 8%, WCA increased from 68° to 165°. Surface topography of the coatings was examined using scanning electron microscopy (SEM). Nano-particles covered on the coating surface formed continuous film with greatly enhanced roughness, which was found to be responsible for the superhydrophobicity. The method is simple and cost effective and can be used for preparing self-cleaning superhydrophobic coating on large areas.

Electron beam injection during active experiments. I - Electromagnetic wave emissions

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Kellogg, P. J.

1990-01-01

The wave emissions produced in Echo 7 experiment by active injections of electron beams were investigated to determine the properties of the electromagnetic and electrostatic fields for both the field-aligned and cross-field injection in such experiments and to evaluate the sources of free energy and relative efficiencies for the generation of the VLF and HF emissions. It is shown that, for typical beam energies in active experiments, electromagnetic effects do not substantially change the bulk properties of the beam, spacecraft charging, and plasma particle acceleration. Through simulations, beam-generated whistlers; fundamental z-mode and harmonic x-mode radiation; and electrostatic electron-cyclotron, upper-hybrid, Langmuir, and lower-hybrid waves were identified. The characteristics of the observed wave spectra were found to be sensitive to both the ratio of the electron plasma frequency to the cyclotron frequency and the angle of injection relative to the magnetic field.

Improvement of infrared single-photon detectors absorptance by integrated plasmonic structures

PubMed Central

Csete, Mária; Sipos, Áron; Szalai, Anikó; Najafi, Faraz; Szabó, Gábor; Berggren, Karl K.

2013-01-01

Plasmonic structures open novel avenues in photodetector development. Optimized illumination configurations are reported to improve p-polarized light absorptance in superconducting-nanowire single-photon detectors (SNSPDs) comprising short- and long-periodic niobium-nitride (NbN) stripe-patterns. In OC-SNSPDs consisting of ~quarter-wavelength dielectric layer closed by a gold reflector the highest absorptance is attainable at perpendicular incidence onto NbN patterns in P-orientation due to E-field concentration at the bottom of nano-cavities. In NCAI-SNSPDs integrated with nano-cavity-arrays consisting of vertical and horizontal gold segments off-axis illumination in S-orientation results in polar-angle-independent perfect absorptance via collective resonances in short-periodic design, while in long-periodic NCAI-SNSPDs grating-coupled surface waves promote EM-field transportation to the NbN stripes and result in local absorptance maxima. In NCDAI-SNSPDs integrated with nano-cavity-deflector-array consisting of longer vertical gold segments large absorptance maxima appear in 3p-periodic designs due to E-field enhancement via grating-coupled surface waves synchronized with the NbN stripes in S-orientation, which enable to compensate fill-factor-related retrogression. PMID:23934331

New results in low-energy fusion of 40Ca+Zr,9290

NASA Astrophysics Data System (ADS)

Stefanini, A. M.; Montagnoli, G.; Esbensen, H.; Čolović, P.; Corradi, L.; Fioretto, E.; Galtarossa, F.; Goasduff, A.; Grebosz, J.; Haas, F.; Mazzocco, M.; Soić, N.; Strano, E.; Szilner, S.

2017-07-01

Background: Near- and sub-barrier fusion of various Ca + Zr isotopic combinations have been widely investigated. A recent analysis of 40Ca+96Zr data has highlighted the importance of couplings to multiphonon excitations and to both neutron and proton transfer channels. Analogous studies of 40Ca+90Zr tend to exclude any role of transfer couplings. However, the lowest measured cross section for this system is rather high (840 μ b ). A rather complete data set is available for 40Ca+94Zr , while no measurement of 40Ca+92Zr fusion has been performed in the past. Purpose: Our aim is to measure the full excitation function of 40Ca+92Zr near the barrier and to extend downward the existing data on 40Ca+90Zr , in order to estimate the transfer couplings that should be used in coupled-channels calculations of the fusion of these two systems and of 40Ca+94Zr . Methods: 40Ca beams from the XTU Tandem accelerator of INFN-Laboratori Nazionali di Legnaro were used, bombarding thin metallic 90Zr (50 μ g /cm2 ) and 92ZrO2 targets (same thickness) enriched to 99.36 % and 98.06 % in masses 90 and 92, respectively. An electrostatic beam deflector allowed the detection of fusion evaporation residues (ER) at very forward angles, and angular distributions of ER were measured. Results: The excitation function of 40Ca+92Zr has been measured down to the level of ≃60 μ b . Coupled-channels (CC) calculations using a standard Woods-Saxon (WS) potential and following the line of a previous analysis of 40Ca+96Zr fusion data give a good account of the new data, as well as of the existing data for 40Ca+94Zr . The previous excitation function of 40Ca+90Zr has been extended down to 40 μ b . Conclusions: Transfer couplings play an important role in explaining the fusion data for 40Ca+92Zr and 40Ca+94Zr . The strength of the pair-transfer coupling is deduced by applying a simple recipe based on the value obtained for 40Ca+96Zr . The logarithmic slopes and the S factors for fusion are reproduced fairly well for all three systems by the CC calculations, and there are no indications of a fusion hindrance at the lowest energies. In contrast, the new data for 40Ca+90Zr indicate the onset of a fusion hindrance at the lowest energies.

E Complex groundbreaking

NASA Image and Video Library

2009-04-14

Representatives from NASA, Orbital Sciences Corp. and Aerojet participate in a ribbon-cutting ceremony for construction of a flame deflector trench at Stennis Space Center's E Test Complex. Participants included Orbital CEO J.R. Thompson (center, left) and Stennis Space Center Director Gene Goldman (center, right).

Electro-Optic Beam Steering Using Non-Linear Organic Materials

DTIC Science & Technology

1993-08-01

York (SUNY), Buffalo, for potential application to the Hughes electro - optic beam deflector device. Evaluations include electro - optic coefficient...response time, transmission, and resistivity. Electro - optic coefficient measurements were made at 633 nm using a simple reflection technique. The

E Complex groundbreaking

NASA Technical Reports Server (NTRS)

2009-01-01

Representatives from NASA, Orbital Sciences Corp. and Aerojet participate in a ribbon-cutting ceremony for construction of a flame deflector trench at Stennis Space Center's E Test Complex. Participants included Orbital CEO J.R. Thompson (center, left) and Stennis Space Center Director Gene Goldman (center, right).

Point-to-plane and plane-to-plane electrostatic charge injection atomization for insulating liquids

NASA Astrophysics Data System (ADS)

Malkawi, Ghazi

An electrostatic charge injection atomizer was fabricated and used to introduce and study the electrostatic charge injection atomization methods for highly viscous vegetable oils and high conductivity low viscosity aviation fuel, JP8. The total, spray and leakage currents and spray breakup characteristics for these liquids were investigated and compared with Diesel fuel data. Jet breakup and spray atomization mechanism showed differences for vegetable oils and lower viscosity hydrocarbon fuels. For vegetable oils, a bending/spinning instability phenomenon was observed similar to the phenomenon found in liquid jets of high viscosity polymer solutions. The spray tip lengths and cone angles were presented qualitatively and quantitatively and correlated with the appropriate empirical formulas. The different stages of the breakup mechanisms for such oils, as a function of specific charges and flow rates, were discussed. In order to make this method of atomization more suitable for practical use in high flow rate applications, a blunt face electrode (plane-to-plane) was used as the charge emitter in place of a single pointed electrode (point-to-plane). This allowed the use of a multi-orifice emitter that maintained a specific charge with the flow rate increase which could not be achieved with the needle electrode. The effect of the nozzle geometry, liquid physical properties and applied bulk flow on the spray charge, total charge, maximum critical spray specific charge and electrical efficiency compared with the needle point-to-plane atomizer results was presented. Our investigation revealed that the electrical efficiency of the atomizer is dominated by the charge forced convection rate rather than charge transport by ion motilities and liquid motion by the electric field. As a result of the electric coulomb forces between the electrified jets, the multi-orifice atomizer provided a unique means of dispersing the fuel in a hollow cone with wide angles making the new method suitable for variety of combustion applications.

Small-Angle Neutron Scattering Study of Interplay of Attractive and Repulsive Interactions in Nanoparticle-Polymer System.

PubMed

Kumar, Sugam; Aswal, Vinod K; Kohlbrecher, Joachim

2016-02-16

The phase behavior of nanoparticle (silica)-polymer (polyethylene glycol) system without and with an electrolyte (NaCl) has been studied. It is observed that nanoparticle-polymer system behaves very differently in the presence of electrolyte. In the absence of electrolyte, the nanoparticle-polymer system remains in one-phase even at very high polymer concentrations. On the other hand, a re-entrant phase behavior is found in the presence of electrolyte, where one-phase (individual) system undergoes two-phase (nanoparticle aggregation) and then back to one-phase with increasing polymer concentration. The regime of two-phase system has been tuned by varying the electrolyte concentration. The polymer concentration range over which the two-phase system exists is significantly enhanced with the increase in the electrolyte concentration. These systems have been characterized by small-angle neutron scattering (SANS) experiments of contrast-marching the polymer to the solvent. The data are modeled using a two-Yukawa potential accounting for both attractive and repulsive parts of the interaction between nanoparticles. The phase behavior of nanoparticle-polymer system is explained by interplay of attractive (polymer-induced attractive depletion between nanoparticles) and repulsive (nanoparticle-nanoparticle electrostatic repulsion and polymer-polymer repulsion) interactions present in the system. In the absence of electrolyte, the strong electrostatic repulsion between nanoparticles dominates over the polymer-induced depletion attraction and the nanoparticle system remains in one-phase. With addition of electrolyte, depletion attraction overcomes electrostatic repulsion at some polymer concentration, resulting into nanoparticle aggregation and two-phase system. Further addition of polymer increases the polymer-polymer repulsion which eventually reduces the strength of depletion and hence re-entrant phase behavior. The effects of varying electrolyte concentration on the phase behavior of nanoparticle-polymer system are understood in terms of modifications in nanoparticle-nanoparticle and polymer-polymer interactions. The nanoparticle aggregates in two-phase systems are found to have surface fractal morphology.

Direct RF A-O Processor Spectrum Analyzer.

DTIC Science & Technology

1981-08-01

The primary objective was to develop and demonstrate design approach, along with the associated processing technologies, for a wideband acousto optic Bragg...cell spectrum analyzer. The signal processor used to demonstrate feasibility of the technical approach consisted of two bulk wave acousto optic deflectors

225. Photocopy of drawing (1967 structural drawing by General Dynamics/Astronautics) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

225. Photocopy of drawing (1967 structural drawing by General Dynamics/Astronautics) WIND DEFLECTOR FOR THE UMBILICAL MAST, SHEET S122 - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

DELUGE AND WATER RECLAMATION BASIN BELOW TEST STAND 1A. Looking ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DELUGE AND WATER RECLAMATION BASIN BELOW TEST STAND 1-A. Looking north northwest - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Flame Deflector Water System, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

29 CFR 1910.27 - Fixed ladders.

Code of Federal Regulations, 2014 CFR

2014-07-01

... unbroken length of 30 feet. EC27OC91.005 Figure D-5—Deflector Plates for Head Hazards EC27OC91.006 Figure D.... Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage...

29 CFR 1910.27 - Fixed ladders.

Code of Federal Regulations, 2011 CFR

2011-07-01

... unbroken length of 30 feet. EC27OC91.005 Figure D-5—Deflector Plates for Head Hazards EC27OC91.006 Figure D.... Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage...

29 CFR 1910.27 - Fixed ladders.

Code of Federal Regulations, 2013 CFR

2013-07-01

... unbroken length of 30 feet. EC27OC91.005 Figure D-5—Deflector Plates for Head Hazards EC27OC91.006 Figure D.... Vertical bars shall be located at a maximum spacing of 40 degrees around the circumference of the cage...

Wetting of a Charged Surface of Glassy Carbon by Molten Alkali-Metal Chlorides

NASA Astrophysics Data System (ADS)

Stepanov, V. P.

2018-03-01

Values of the contact angle of wetting of a surface of glassy carbon by molten chlorides of lithium, sodium, potassium, and cesium are measured by the meniscus weight method to determine the common factors of wettability of solid surfaces by ionic melts upon a change in the salt phase composition and a jump in electric potential. It is found that with a potential shift in the positive direction the shape of the curve of the contact angle's dependence on the potential varies upon substitution of one salt by another: the angle of wetting shrinks monotonously in lithium chloride but remains constant in molten cesium chloride. This phenomenon is explained by the hypothesis that the nature of the halide anion adsorption on the positively charged surface of an electrode is chemical and not electrostatic. It is shown that the adsorption process is accompanied by charge transfer through the interface, with covalent bonding between the adsorbent and adsorbate.

Integrated wide-angle scanner based on translating a curved mirror of acylindrical shape.

PubMed

Sabry, Yasser M; Khalil, Diaa; Saadany, Bassam; Bourouina, Tarik

2013-06-17

A wide angle microscanning architecture is presented in which the angular deflection is achieved by displacing the principle axis of a curved silicon micromirror of acylindrical shape, with respect to the incident beam optical axis. The micromirror curvature is designed to overcome the possible deformation of the scanned beam spot size during scanning. In the presented architecture, the optical axis of the beam lays in-plane with respect to the substrate opening the door for a completely integrated and self-aligned miniaturized scanner. A micro-optical bench scanning device, based on translating a 200 μm focal length micromirror by an electrostatic comb-drive actuator, is implemented on a silicon chip. The microelectromechanical system has a resonance frequency of 329 Hz and a quality factor of 22. A single-mode optical fiber is used as the optical source and inserted into a micromachined groove fabricated and lithographically aligned with the microbench. Optical deflection angles up to 110 degrees are demonstrated.

Rocket measurements of energetic particles in the midlatitude precipitation zone

NASA Technical Reports Server (NTRS)

Voss, H. D.; Smith, L. G.; Braswell, F. M.

1980-01-01

Measurements of energetic ion and electron properties as a function of altitude in the midlatitude zone of nighttime energetic particle precipitation are reported. The measurements of particle fluxes, energy spectra and pitch angle distributions were obtained by a Langmuir probe, six energetic particle spectrometers and an electrostatic analyzer on board a Nike Apache rocket launched near the center of the midlatitude zone during disturbed conditions. It is found that the incident flux was primarily absorbed rather than backscattered, and consists of mainly energetic hydrogen together with some helium and a small energetic electron component. Observed differential energy spectra of protons having an exponential energy spectrum, and pitch angle distributions at various altitudes indicate that the energetic particle flux decreases rapidly for pitch angles less than 70 deg. An energetic particle energy flux of 0.002 ergs/sq cm per sec is calculated which indicates the significance of energetic particles as a primary nighttime ionization source for altitudes between 120 and 200 km in the midlatitude precipitation zone.

Spectroscopy and high-resolution imaging of the gravitational lens SDSS J1206+4332

NASA Astrophysics Data System (ADS)

Agnello, Adriano; Sonnenfeld, Alessandro; Suyu, Sherry H.; Treu, Tommaso; Fassnacht, Christopher D.; Mason, Charlotte; Bradač, Maruša; Auger, Matthew W.

2016-06-01

We present spectroscopy and laser guide star adaptive optics (LGSAO) images of the doubly imaged lensed quasar SDSS J1206+4332. We revise the deflector redshift proposed previously to zd = 0.745, and measure for the first time its velocity dispersion σ = (290 ± 30) km s-1. The LGSAO data show the lensed quasar host galaxy stretching over the astroid caustic thus forming an extra pair of merging images, which was previously thought to be an unrelated galaxy in seeing limited data. Owing to the peculiar geometry, the lens acts as a natural coronagraph on the broad-line region of the quasar so that only narrow C III]emission is found in the fold arc. We use the data to reconstruct the source structure and deflector potential, including nearby perturbers. We reconstruct the point-spread function (PSF) from the quasar images themselves, since no additional point source is present in the field of view. From gravitational lensing and stellar dynamics, we find the slope of the total mass density profile to be γ' = -log ρ/log r = 1.93 ± 0.09. We discuss the potential of SDSS J1206+4332 for measuring a time-delay distance (and thus H0 and other cosmological parameters), or as a standard ruler, in combination with the time-delay published by the COSMOGRAIL collaboration. We conclude that this system is very promising for cosmography. However, in order to achieve competitive precision and accuracy, an independent characterization of the PSF is needed. Spatially resolved kinematics of the deflector would reduce the uncertainties further. Both are within the reach of current observational facilities.

No moving parts safe & arm apparatus and method with monitoring and built-in-test for optical firing of explosive systems

DOEpatents

Hendrix, J.L.

1995-04-11

A laser initiated ordnance controller apparatus which provides a safe and arm scheme with no moving parts. The safe & arm apparatus provides isolation of firing energy to explosive devices using a combination of polarization isolation and control through acousto-optical deviation of laser energy pulses. The apparatus provides constant monitoring of the systems status and performs 100% built-in-test at any time prior to ordnance ignition without the risk of premature ignition or detonation. The apparatus has a computer controller, a solid state laser, an acousto-optic deflector and RF drive circuitry, built-in-test optics and electronics, and system monitoring capabilities. The optical system is completed from the laser beam power source to the pyrotechnic ordnance through fiber optic cabling, optical splitters and optical connectors. During operation of the apparatus, a command is provided by the computer controller and, simultaneous with laser flashlamp fire, the safe & arm device is opened for approximately 200 microseconds which allows the laser pulse to transmit through the device. The arm signal also energizes the laser power supply and activates the acousto-optical deflector. When the correct fire format command is received, the acousto-optic deflector moves to the selected event channel, and the channel is verified to ensure the system is pointing to the correct position. Laser energy is transmitted through the fiber where an ignitor or detonator designed to be sensitive to optical pulses is fired at the end of the fiber channel. Simultaneous event channels may also be utilized by optically splitting a single event channel. The built-in-test may be performed anytime prior to ordnance ignition. 6 figures.

No moving parts safe & arm apparatus and method with monitoring and built-in-test for optical firing of explosive systems

DOEpatents

Hendrix, James L.

1995-01-01

A laser initiated ordnance controller apparatus which provides a safe and m scheme with no moving parts. The safe & arm apparatus provides isolation of firing energy to explosive devices using a combination of polarization isolation and control through acousto-optical deviation of laser energy pulses. The apparatus provides constant monitoring of the systems status and performs 100% built-in-test at any time prior to ordnance ignition without the risk of premature ignition or detonation. The apparatus has a computer controller, a solid state laser, an acousto-optic deflector and RF drive circuitry, built-in-test optics and electronics, and system monitoring capabilities. The optical system is completed from the laser beam power source to the pyrotechnic ordnance through fiber optic cabling, optical splitters and optical connectors. During operation of the apparatus, a command is provided by the computer controller and, simultaneous with laser flashlamp fire, the safe & arm device is opened for approximately 200 microseconds which allows the laser pulse to transmit through the device. The arm signal also energizes the laser power supply and activates the acousto-optical deflector. When the correct fire format command is received, the acousto-optic deflector moves to the selected event channel, and the channel is verified to ensure the system is pointing to the correct position. Laser energy is transmitted through the fiber where an ignitor or detonator designed to be sensitive to optical pulses is fired at the end of the fiber channel. Simultaneous event channels may also be utilized by optically splitting a single event channel. The built-in-test may be performed anytime prior to ordnance ignition.

Gravitational lensing in modified Newtonian dynamics

NASA Astrophysics Data System (ADS)

Mortlock, Daniel J.; Turner, Edwin L.

2001-10-01

Modified Newtonian dynamics (MOND) is an alternative theory of gravity that aims to explain large-scale dynamics without recourse to any form of dark matter. However, the theory is incomplete, lacking a relativistic counterpart, and so makes no definite predictions about gravitational lensing. The most obvious form that MONDian lensing might take is that photons experience twice the deflection of massive particles moving at the speed of light, as in general relativity (GR). In such a theory there is no general thin-lens approximation (although one can be made for spherically symmetric deflectors), but the three-dimensional acceleration of photons is in the same direction as the relativistic acceleration would be. In regimes where the deflector can reasonably be approximated as a single point-mass (specifically low-optical depth microlensing and weak galaxy-galaxy lensing), this naive formulation is consistent with observations. Forthcoming galaxy-galaxy lensing data and the possibility of cosmological microlensing have the potential to distinguish unambiguously between GR and MOND. Some tests can also be performed with extended deflectors, for example by using surface brightness measurements of lens galaxies to model quasar lenses, although the breakdown of the thin-lens approximation allows an extra degree of freedom. None the less, it seems unlikely that simple ellipsoidal galaxies can satisfy both constraints. Furthermore, the low-density universe implied by MOND must be completely dominated by the cosmological constant (to fit microwave background observations), and such models are at odds with the low frequency of quasar lenses. These conflicts might be resolved by a fully consistent relativistic extension to MOND; the alternative is that MOND is not an accurate description of the Universe.

Charge transfer properties of pentacene adsorbed on silver: DFT study

NASA Astrophysics Data System (ADS)

N, Rekha T.; Rajkumar, Beulah J. M.

2015-06-01

Charge transfer properties of pentacene adsorbed on silver is investigated using DFT methods. Optimized geometry of pentacene after adsorption on silver indicates distortion in hexagonal structure of the ring close to the silver cluster and deviations in co-planarity of carbon atoms due to the variations in bond angles and dihedral angles. Theoretically simulated absorption spectrum has a symmetric surface plasmon resonance peak around 486nm corresponding to the transfer of charge from HOMO-2 to LUMO. Theoretical SERS confirms the process of adsorption, tilted orientation of pentacene on silver surface and the charge transfers reported. Localization of electron density arising from redistribution of electrostatic potential together with a reduced bandgap of pentacene after adsorption on silver suggests its utility in the design of electro active organic semiconducting devices.

Valve for abrasive material

DOEpatents

Gardner, Harold S.

1982-01-01

A ball valve assembly for controlling the flow of abrasive particulates including an enlarged section at the bore inlet and an enlarged section at the bore outlet. A refractory ceramic annular deflector is positioned in each of the enlarged sections, substantially extending the useful life of the valve.

A low-level rf control system for a quarter-wave resonator

NASA Astrophysics Data System (ADS)

Kim, Jongwon; Hwang, Churlkew

2012-06-01

A low-level rf control system was designed and built for an rf deflector, which is a quarter wave resonator, and was designed to deflect a secondary electron beam to measure the bunch length of an ion beam. The deflector has a resonance frequency near 88 MHz, its required phase stability is approximately ±1° and its amplitude stability is less than ±1%. The control system consists of analog input and output components and a digital system based on a field-programmable gate array for signal processing. The system is cost effective, while meeting the stability requirements. Some basic properties of the control system were measured. Then, the capability of the rf control was tested using a mechanical vibrator made of a dielectric rod attached to an audio speaker system, which could induce regulated perturbations in the electric fields of the resonator. The control system was flexible so that its parameters could be easily configured to compensate for the disturbance induced in the resonator.

Application of the Collision-Imparted Velocity Method for Analyzing the Responses of Containment and Deflector Structures to Engine Rotor Fragment Impact

NASA Technical Reports Server (NTRS)

Collins, T. P.; Witmer, E. A.

1973-01-01

An approximate analysis, termed the Collision Imparted Velocity Method (CIVM), was employed for predicting the transient structural responses of containment rings or deflector rings which are subjected to impact from turbojet-engine rotor burst fragments. These 2-d structural rings may be initially circular or arbitrarily curved and may have either uniform or variable thickness; elastic, strain hardening, and strain rate material properties are accommodated. This approximate analysis utilizes kinetic energy and momentum conservation relations in order to predict the after-impact velocities of the fragment and the impacted ring segment. This information is then used in conjunction with a finite element structural response computation code to predict the transient, large deflection responses of the ring. Similarly, the equations of motion for each fragment are solved in small steps in time. Also, some comparisons of predictions with experimental data for fragment-impacted free containment rings are presented.

Electrostatic immobilization of antimicrobial peptides on polyethylenimine and their antibacterial effect against Staphylococcus epidermidis.

PubMed

Hernandez-Montelongo, J; Corrales Ureña, Y R; Machado, D; Lancelloti, M; Pinheiro, M P; Rischka, K; Lisboa-Filho, P N; Cotta, M A

2018-04-01

Staphylococcus epidermidis is a gram-positive bacterium, and one of the most prevalent causes of nosocomial infections due to its strong ability to form biofilms on catheters and surgical implants. Here we explore the antimicrobial properties of Tet-124 peptides, which are part of the innate defense against different multicellular organisms in nature. Two different Tet-124 peptides were immobilized on a polyethylenimine (PEI) film to determine their impact on the antimicrobial properties: KLWWMIRRW (Tet-124), which contains only natural amino acids, and KLWWMIRRWG-(F-Br)-G (F-Br = 4-Bromophenylalanine), a modified Tet-124 sequence with the addition of an unnatural amino acid. The immobilization was obtained as a result of the electrostatic interaction between PEI amino groups and the C-terminal carboxylic groups of tryptophan and glycine amino acids of Tet-124 and Tet-124-Br peptides, respectively. The process was monitored and studied by water contact angle, Atomic Force Microscopy (AFM), X-ray Photoelectron Spectroscopy (XPS) and Quartz Crystal Microbalance with Dissipation (QCM-D) measurements. The antibacterial effect of our samples against S. epidermis was evaluated by the spread plate counting method, and cytotoxicity was tested using fibroblast cultures. Our results indicate the feasibility to immobilize electrostatically both Tet-124 peptides for biomedical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

Polarizable continuum model associated with the self-consistent-reaction field for molecular adsorbates at the interface.

PubMed

Wang, Jing-Bo; Ma, Jian-Yi; Li, Xiang-Yuan

2010-01-07

In this work, a new procedure has been developed in order to realize the self-consistent-reaction field computation for interfacial molecules. Based on the extension of the dielectric polarizable continuum model, the quantum-continuum calculations for interfacial molecules have been carried out. This work presents an investigation into how the molecular structure influences the adsorbate-solvent interaction and consequently alters the orientation angle at the air/water interface. Taking both electrostatic and non-electrostatic energies into account, we investigate the orientation behavior of three interfacial molecules, 2,6-dimethyl-4-hydroxy-benzonitrile, 3,5-dimethyl-4-hydroxy-benzonitrile and p-cyanophenol, at the air/water interface. The results show that the hydrophilic hydroxyl groups in 2,6-dimethyl-4-hydroxy-benzonitrile and in p-cyanophenol point from the air to the water side, but the hydroxyl group in 3,5-dimethyl-4-hydroxy-benzonitrile takes the opposite direction. Our detailed analysis reveals that the opposite orientation of 3,5-dimethyl-4-hydroxy-benzonitrile results mainly from the cavitation energy. The different orientations of the hydrophilic hydroxyl group indicate the competition of electrostatic and cavitation energies. The theoretical prediction gives a satisfied explanation of the most recent sum frequency generation measurement for these molecules at the interface.

Finite element analysis of a micromechanical deformable mirror device

NASA Technical Reports Server (NTRS)

Sheerer, T. J.; Nelson, W. E.; Hornbeck, L. J.

1989-01-01

A monolithic spatial light modulator chip was developed consisting of a large number of micrometer-scale mirror cells which can be rotated through an angle by application of an electrostatic field. The field is generated by electronics integral to the chip. The chip has application in photoreceptor based non-impact printing technologies. Chips containing over 16000 cells were fabricated, and were tested to several billions of cycles. Finite Element Analysis (FEA) of the device was used to model both the electrical and mechanical characteristics.

The theoretical simulation on electrostatic distribution of 1st proximity region in proximity focusing low-light-level image intensifier

NASA Astrophysics Data System (ADS)

Zhang, Liandong; Bai, Xiaofeng; Song, De; Fu, Shencheng; Li, Ye; Duanmu, Qingduo

2015-03-01

Low-light-level night vision technology is magnifying low light level signal large enough to be seen by naked eye, which uses the photons - photoelectron as information carrier. Until the micro-channel plate was invented, it has been possibility for the realization of high performance and miniaturization of low-light-level night vision device. The device is double-proximity focusing low-light-level image intensifier which places a micro-channel plate close to photocathode and phosphor screen. The advantages of proximity focusing low-light-level night vision are small size, light weight, small power consumption, no distortion, fast response speed, wide dynamic range and so on. It is placed parallel to each other for Micro-channel plate (both sides of it with metal electrode), the photocathode and the phosphor screen are placed parallel to each other. The voltage is applied between photocathode and the input of micro-channel plate when image intensifier works. The emission electron excited by photo on the photocathode move towards to micro-channel plate under the electric field in 1st proximity focusing region, and then it is multiplied through the micro-channel. The movement locus of emission electrons can be calculated and simulated when the distributions of electrostatic field equipotential lines are determined in the 1st proximity focusing region. Furthermore the resolution of image tube can be determined. However the distributions of electrostatic fields and equipotential lines are complex due to a lot of micro-channel existing in the micro channel plate. This paper simulates electrostatic distribution of 1st proximity region in double-proximity focusing low-light-level image intensifier with the finite element simulation analysis software Ansoft maxwell 3D. The electrostatic field distributions of 1st proximity region are compared when the micro-channel plates' pore size, spacing and inclination angle ranged. We believe that the electron beam movement trajectory in 1st proximity region will be better simulated when the electronic electrostatic fields are simulated.

Recent H- diagnostics, plasma simulations, and 2X scaled Penning ion source developments at the Rutherford Appleton Laboratory

NASA Astrophysics Data System (ADS)

Lawrie, S. R.; Faircloth, D. C.; Smith, J. D.; Sarmento, T. M.; Whitehead, M. O.; Wood, T.; Perkins, M.; Macgregor, J.; Abel, R.

2018-05-01

A vessel for extraction and source plasma analyses is being used for Penning H- ion source development at the Rutherford Appleton Laboratory. A new set of optical elements including an einzel lens has been installed, which transports over 80 mA of H- beam successfully. Simultaneously, a 2X scaled Penning source has been developed to reduce cathode power density. The 2X source is now delivering a 65 mA H- ion beam at 10% duty factor, meeting its design criteria. The long-term viability of the einzel lens and 2X source is now being evaluated, so new diagnostic devices have been installed. A pair of electrostatic deflector plates is used to correct beam misalignment and perform fast chopping, with a voltage rise time of 24 ns. A suite of four quartz crystal microbalances has shown that the cesium flux in the vacuum vessel is only increased by a factor of two, despite the absence of a dedicated cold trap. Finally, an infrared camera has demonstrated good agreement with thermal simulations but has indicated unexpected heating due to beam loss on the downstream electrode. These types of diagnostics are suitable for monitoring all operational ion sources. In addition to experimental campaigns and new diagnostic tools, the high-performance VSim and COMSOL software packages are being used for plasma simulations of two novel ion thrusters for space propulsion applications. In parallel, a VSim framework has been established to include arbitrary temperature and cesium fields to allow the modeling of surface physics in H- ion sources.

A nanosecond pulsing system for MeV light ions using a 2 MV Tandetron TM

NASA Astrophysics Data System (ADS)

Mous, D. J. W.; Visser, J.; Haitsma, R. G.

2004-06-01

A nanosecond pulsing system for H, D and He ions has been developed to satisfy the demands of a new neutron reference field (2 keV-20 MeV) for neutron metrology and dosimetry at the Institute for Radiological Protection and Nuclear Safety (IRSN) [Gressier et al., Proceedings of the Symposium on Radiation Measurements and Applications 2002, University of Michigan, Michigan, USA, Nucl. Instr. and Meth. A 505 (2003) 370]. The system is capable of delivering ion energies of 0.2-4 MeV at target with currents of 50 and 8 μA in DC and pulsed mode, respectively. The injector consists of a multi-cusp, direct negative extraction ion source operating at a relative low extraction voltage of 25 kV, which keeps system dimensions small and minimises the energy modulation of the buncher as well as the resulting beam energy spread on target. The chopper can operate at repetition frequencies between 62.5 and 2000 kHz and features additional electrostatic deflectors that cancel the energy spread that is inherently imposed on the beam by chopping. This unique and patented feature eliminates one of the main contributions that fundamentally limits the achievable pulse width on target. At the high-energy side of the accelerator an isochronous set of magnets preserve the time correlation of the ions in the bunch. The first magnet (90°) is equipped with NMR stabilisation and slit feedback to give an absolute reference of the particle energy, which is essential for the present application.

United States Department of Agriculture-Agricultural Research Service research in application technology for pest management.

PubMed

Smith, L A; Thomson, S J

2003-01-01

A research summary is presented that emphasizes ARS achievements in application technology over the past 2-3 years. Research focused on the improvement of agricultural pesticide application is important from the standpoint of crop protection as well as environmental safety. Application technology research is being actively pursued within the ARS, with a primary focus on application system development, drift management, efficacy enhancement and remote sensing. Research on application systems has included sensor-controlled hooded sprayers, new approaches to direct chemical injection, and aerial electrostatic sprayers. For aerial application, great improvements in on-board flow controllers permit accurate field application of chemicals. Aircraft parameters such as boom position and spray release height are being altered to determine their effect on drift. Other drift management research has focused on testing of low-drift nozzles, evaluation of pulsed spray technologies and evaluation of drift control adjuvants. Research on the use of air curtain sprayers in orchards, air-assist sprayers for row crops and vegetables, and air deflectors on aircraft has documented improvements in application efficacy. Research has shown that the fate of applied chemicals is influenced by soil properties, and this has implications for herbicide efficacy and dissipation in the environment. Remote sensing systems are being used to target areas in the field where pests are present so that spray can be directed to only those areas. Soil and crop conditions influence propensity for weeds and insects to proliferate in any given field area. Research has indicated distinct field patterns favorable for weed growth and insect concentration, which can provide further assistance for targeted spraying.

THOR Ion Mass Spectrometer instrument - IMS

NASA Astrophysics Data System (ADS)

Retinò, Alessandro; Kucharek, Harald; Saito, Yoshifumi; Fraenz, Markus; Verdeil, Christophe; Leblanc, Frederic; Techer, Jean-Denis; Jeandet, Alexis; Macri, John; Gaidos, John; Granoff, Mark; Yokota, Shoichiro; Fontaine, Dominique; Berthomier, Matthieu; Delcourt, Dominique; Kistler, Lynn; Galvin, Antoniette; Kasahara, Satoshi; Kronberg, Elena

2016-04-01

Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. Specifically, THOR will study how turbulent fluctuations at kinetic scales heat and accelerate particles in different turbulent environments within the near-Earth space. To achieve this goal, THOR payload is being designed to measure electromagnetic fields and particle distribution functions with unprecedented resolution and accuracy. Here we present the Ion Mass Spectrometer (IMS) instrument that will measure the full three-dimensional distribution functions of near-Earth main ion species (H+, He+, He++ and O+) at high time resolution (~ 150 ms for H+ , ~ 300 ms for He++) with energy resolution down to ~ 10% in the range 10 eV/q to 30 keV/q and angular resolution ~ 10°. Such high time resolution is achieved by mounting multiple sensors around the spacecraft body, in similar fashion to the MMS/FPI instrument. Each sensor combines a top-hat electrostatic analyzer with deflectors at the entrance together with a time-of-flight section to perform mass selection. IMS electronics includes a fast sweeping high voltage board that is required to make measurements at high cadence. Ion detection includes Micro Channel Plates (MCP) combined with Application-Specific Integrated Circuits (ASICs) for charge amplification, discrimination and time-to-digital conversion (TDC). IMS is being designed to address many of THOR science requirements, in particular ion heating and acceleration by turbulent fluctuations in foreshock, shock and magnetosheath regions. The IMS instrument is being designed and will be built by an international consortium of scientific institutes with main hardware contributions from France, USA, Japan and Germany.

Growth of Acousto-Optic Crystals for Applications in Infrared Region of Spectrum

DTIC Science & Technology

2005-04-30

Acousto - optic (AO) modulators, deflectors, filters offer convenience, reliability, compact size and fast speed in regulation of optical beams. So far...extremely low acousto - optic figure of merit, which automatically results in high requirements on driving electric power and poor diffraction efficiency. It

Stream Management: A Rebirth

ERIC Educational Resources Information Center

Coler, Robert A.; Zatryka, Simon A.

1974-01-01

This article describes a stream management course designed to give non-science majors an in-depth study of water quality. The course includes work in determining and measuring water quality parameters and the discussion of management techniques. Construction of a Hewitt Ramp and wing deflectors are illustrated in the article. (MA)

224. Photocopy of drawing (1963 structural drawing by General Dynamics/Astronautics) ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

224. Photocopy of drawing (1963 structural drawing by General Dynamics/Astronautics) UMBILICAL MAST WIND DEFLECTOR REQUIRED FOR 206 PROGRAM, PAD, SHEET S-101 - Vandenberg Air Force Base, Space Launch Complex 3, Launch Pad 3 East, Napa & Alden Roads, Lompoc, Santa Barbara County, CA

8. VIEW OF NEW CONSTRUCTION ON LAUNCH DECK WITH CASTINPLACE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

8. VIEW OF NEW CONSTRUCTION ON LAUNCH DECK WITH CAST-IN-PLACE CONCRETE WALLS AND STEEL STRUCTURE FOR NEW SOUTH-FACING FLAME DEFLECTOR; VIEW TO EAST. - Cape Canaveral Air Station, Launch Complex 17, Facility 28402, East end of Lighthouse Road, Cape Canaveral, Brevard County, FL

A bio-inspired device for drag reduction on a three-dimensional model vehicle.

PubMed

Kim, Dongri; Lee, Hoon; Yi, Wook; Choi, Haecheon

2016-03-10

In this paper, we introduce a bio-mimetic device for the reduction of the drag force on a three-dimensional model vehicle, the Ahmed body (Ahmed et al 1984 SAE Technical Paper 840300). The device, called automatic moving deflector (AMD), is designed inspired by the movement of secondary feathers on bird's wing suction surface: i.e., secondary feathers pop up when massive separation occurs on bird's wing suction surface at high angles of attack, which increases the lift force at landing. The AMD is applied to the rear slanted surface of the Ahmed body to control the flow separation there. The angle of the slanted surface considered is 25° at which the drag coefficient on the Ahmed body is highest. The wind tunnel experiment is conducted at Re H  = 1.0 × 10(5)-3.8 × 10(5), based on the height of the Ahmed body (H) and the free-stream velocity (U ∞). Several AMDs of different sizes and materials are tested by measuring the drag force on the Ahmed body, and showed drag reductions up to 19%. The velocity and surface-pressure measurements show that AMD starts to pop up when the pressure in the thin gap between the slanted surface and AMD is much larger than that on the upper surface of AMD. We also derive an empirical formula that predicts the critical free-stream velocity at which AMD starts to operate. Finally, it is shown that the drag reduction by AMD is mainly attributed to a pressure recovery on the slanted surface by delaying the flow separation and suppressing the strength of the longitudinal vortices emanating from the lateral edges of the slanted surface.

Understanding Rubredoxin Redox Sites by Density Functional Theory Studies of Analogues

PubMed Central

Luo, Yan; Niu, Shuqiang; Ichiye, Toshiko

2012-01-01

Determining the redox energetics of redox site analogues of metalloproteins is essential in unraveling the various contributions to electron transfer properties of these proteins. Since studies of the [4Fe-4S] analogues show that the energies are dependent on the ligand dihedral angles, broken symmetry density functional theory (BS-DFT) with the B3LYP functional and double-ζ basis sets calculations of optimized geometries and electron detachment energies of [1Fe] rubredoxin analogues are compared to crystal structures and gas-phase photoelectron spectroscopy data, respectively, for [Fe(SCH3)4]0/1-/2-, [Fe(S2-o-xyl2)]0/1-/2-, and Na+[Fe(S2-o-xyl)2]1-/2- in different conformations. In particular, the study of Na+[Fe(S2-o-xyl)2]1-/2- is the only direct comparison of calculated and experimental gas phase detachment energies for the 1-/2- couple found in the rubredoxins. These results show that variations in the inner sphere energetics by up to ~0.4 eV can be caused by differences in the ligand dihedral angles in either or both redox states. Moreover, these results indicate that the protein stabilizes the conformation that favors reduction. In addition, the free energies and reorganization energies of oxidation and reduction as well as electrostatic potential charges are calculated, which can be used as estimates in continuum electrostatic calculations of electron transfer properties of [1Fe] proteins. PMID:22881577

Vegetative environmental buffers and exhaust fan deflectors for reducing downwind odor and VOCs from tunnel-ventilated swine barns

USDA-ARS?s Scientific Manuscript database

Scientists have investigated methods for reducing odor emissions from livestock buildings for decades, yet few technologies have proven effective. Vegetative Environmental Buffers (VEB), which are specially designed combinations of trees, shrubs and grasses, have shown promise in recent years for r...

Lasers for Training Devices.

ERIC Educational Resources Information Center

Fuller, C. A.

A breadboard model of a laser display system is described in detail and its operating procedure is outlined. The system consists of: a Model 52 argon krypton ion laser and power supply; an optical breadboard comprising a pocket cell light modulator, a galvonmeter beam deflector for vertical scanning, a unique multiple reflection beam steerer for…

PUMP SETS NO. 5 AND NO. 4. Each pump set ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

PUMP SETS NO. 5 AND NO. 4. Each pump set consists of a Worthington Pump and a General Electric motor - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Flame Deflector Water System, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

ONE MILLION GALLON WATER TANK, PUMP HEADER PIPE (AT LEFT), ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

ONE MILLION GALLON WATER TANK, PUMP HEADER PIPE (AT LEFT), HEADER BYPASS PIPE (AT RIGHT), AND PUMPHOUSE FOUNDATIONS. Looking northeast - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Flame Deflector Water System, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

DETAIL VIEW OF THE STRUCTURE OF THE BASE OF THE ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

DETAIL VIEW OF THE STRUCTURE OF THE BASE OF THE TEST STAND AND THE TAIL SECTION OF A REDSTONE (JUPITER) ROCKET. NOTE THE FLAME DEFLECTOR BEHIND THE STRUCTURE IN THE FOREGROUND. - Marshall Space Flight Center, Redstone Rocket (Missile) Test Stand, Dodd Road, Huntsville, Madison County, AL

GENERAL VIEW OF PUMPHOUSE FOUNDATIONS, ALSO SHOWING THREE PUMPS STILL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

GENERAL VIEW OF PUMPHOUSE FOUNDATIONS, ALSO SHOWING THREE PUMPS STILL ON THE PAD, AND THE ELECTRICAL SUBSTATION IN LEFT MIDDLE DISTANCE - Edwards Air Force Base, Air Force Rocket Propulsion Laboratory, Flame Deflector Water System, Test Area 1-120, north end of Jupiter Boulevard, Boron, Kern County, CA

Grit blasting nozzle fabricated from mild tool steel proves satisfactory

NASA Technical Reports Server (NTRS)

Mc Farland, J. E.; Turbitt, B.

1966-01-01

Dry blasting with glass beads through a nozzle assembly descales both the outside and inside surfaces of tubes of Inconel 718 used for the distribution of gaseous oxygen. The inside of the nozzle is coated with polyurethane and the deflector with a commercially available liquid urethane rubber.

Friction Effects on Inertia Compensators used for Heliostat Base Motion Isolation.

DTIC Science & Technology

The base motion isolation of an optical beam deflector with a two-axis gimbal support ( heliostat ) is discussed. The use of an auxiliary inertia...coupled between the elevation gimbal and the heliostat mirror to produce a compensating torque referred to as a gear compensator and a belt compensator

Two-dimensional time-resolved X-ray diffraction study of liquid/solid fraction and solid particle size in Fe-C binary system with an electrostatic levitator furnace

NASA Astrophysics Data System (ADS)

Yonemura, M.; Okada, J.; Watanabe, Y.; Ishikawa, T.; Nanao, S.; Shobu, T.; Toyokawa, H.

2013-03-01

Liquid state provides functions such as matter transport or a reaction field and plays an important role in manufacturing processes such as refining, forging or welding. However, experimental procedures are significantly difficult for an observation of solidification process of iron and iron-based alloys in order to identify rapid transformations subjected to fast temperature evolution. Therefore, in order to study the solidification in iron and iron-based alloys, we considered a combination of high energy X-ray diffraction measurements and an electrostatic levitation method (ESL). In order to analyze the liquid/solid fraction, the solidification of melted spherical specimens was measured at a time resolution of 0.1 seconds during rapid cooling using the two-dimensional time-resolved X-ray diffraction. Furthermore, the observation of particle sizes and phase identification was performed on a trial basis using X-ray small angle scattering with X-ray diffraction.

Interaction of lysozyme protein with different sized silica nanoparticles and their resultant structures

NASA Astrophysics Data System (ADS)

Yadav, Indresh; Aswal, V. K.; Kohlbrecher, J.

2016-05-01

The interaction of model protein-lysozyme with three different sized anionic silica nanoparticles has been studied by UV-vis spectroscopy, dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The surface area and curvature of the nanoparticles change with size, which significantly influence their interaction with protein. The lysozyme adsorbs on the surface of the nanoparticles due to electrostatic attraction and leads to the phase transformation from one phase (clear) to two-phase (turbid) of the nanoparticle-protein system. The dominance of lysozyme induced short-range attraction over long-range electrostatic repulsion between nanoparticles is responsible for phase transformation and modeled by the two-Yukawa potential. The magnitude of the attractive interaction increases with the size of the nanoparticles as a result the phase transformation commences relatively at lower concentration of lysozyme. The structure of the nanoparticle-protein system in two-phase is characterized by the diffusion limited aggregate type of mass fractal morphology.

Interaction of lysozyme protein with different sized silica nanoparticles and their resultant structures

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

Yadav, Indresh, E-mail: iykumarindresh288@gmail.com; Aswal, V. K.; Kohlbrecher, J.

The interaction of model protein-lysozyme with three different sized anionic silica nanoparticles has been studied by UV-vis spectroscopy, dynamic light scattering (DLS) and small-angle neutron scattering (SANS). The surface area and curvature of the nanoparticles change with size, which significantly influence their interaction with protein. The lysozyme adsorbs on the surface of the nanoparticles due to electrostatic attraction and leads to the phase transformation from one phase (clear) to two-phase (turbid) of the nanoparticle-protein system. The dominance of lysozyme induced short-range attraction over long-range electrostatic repulsion between nanoparticles is responsible for phase transformation and modeled by the two-Yukawa potential. Themore » magnitude of the attractive interaction increases with the size of the nanoparticles as a result the phase transformation commences relatively at lower concentration of lysozyme. The structure of the nanoparticle-protein system in two-phase is characterized by the diffusion limited aggregate type of mass fractal morphology.« less

Energetics and Self-Assembly of Amphipathic Peptide Pores in Lipid Membranes

PubMed Central

Zemel, Assaf; Fattal, Deborah R.; Ben-Shaul, Avinoam

2003-01-01

We present a theoretical study of the energetics, equilibrium size, and size distribution of membrane pores composed of electrically charged amphipathic peptides. The peptides are modeled as cylinders (mimicking α-helices) carrying different amounts of charge, with the charge being uniformly distributed over a hydrophilic face, defined by the angle subtended by polar amino acid residues. The free energy of a pore of a given radius, R, and a given number of peptides, s, is expressed as a sum of the peptides' electrostatic charging energy (calculated using Poisson-Boltzmann theory), and the lipid-perturbation energy associated with the formation of a membrane rim (which we model as being semitoroidal) in the gap between neighboring peptides. A simple phenomenological model is used to calculate the membrane perturbation energy. The balance between the opposing forces (namely, the radial free energy derivatives) associated with the electrostatic free energy that favors large R, and the membrane perturbation term that favors small R, dictates the equilibrium properties of the pore. Systematic calculations are reported for circular pores composed of various numbers of peptides, carrying different amounts of charge (1–6 elementary, positive charges) and characterized by different polar angles. We find that the optimal R's, for all (except, possibly, very weakly) charged peptides conform to the “toroidal” pore model, whereby a membrane rim larger than ∼1 nm intervenes between neighboring peptides. Only weakly charged peptides are likely to form “barrel-stave” pores where the peptides essentially touch one another. Treating pore formation as a two-dimensional self-assembly phenomenon, a simple statistical thermodynamic model is formulated and used to calculate pore size distributions. We find that the average pore size and size polydispersity increase with peptide charge and with the amphipathic polar angle. We also argue that the transition of peptides from the adsorbed to the inserted (membrane pore) state is cooperative and thus occurs rather abruptly upon a change in ambient conditions. PMID:12668433

Electrostatic Properties of PE and PTFE Subjected to Atmospheric Pressure Plasma Treatment; Correlation of Experimental Results with Atomistic Modeling

NASA Technical Reports Server (NTRS)

Trigwell, Steve; Boucher, Derrick; Calle, Carlos

2006-01-01

The use of an atmospheric pressure glow discharge (APGD) plasma was used at KSC to increase the hydrophilicity of spaceport materials to enhance their surface charge dissipation and prevent possible ESD in spaceport operations. Significant decreases in charge decay times were observed after tribocharging the materials using the standard KSC tribocharging test. The polarity and amount of charge transferred was dependent upon the effective work function differences between the respective materials. In this study, polyethylene (PE) and polytetrafluoroethylene (PTFE) were exposed to a He+O2 APGD. The pre and post treatment surface chemistry was analyzed by X-ray photoelectron spectroscopy and contact angle measurements. Semi-empirical and ab initio calculations were performed to correlate the experimental results with some plausible molecular and electronic structure features of the oxidation process. For the PE, significant surface oxidation was observed, as indicated by XPS showing C-O, C=O, and O-C=O bonding, and a decrease in the surface contact angle from 98.9 deg to 61.2 deg. For the PTFE, no C-O bonding appeared and the surface contact angle increased indicating the APGD only succeeded in cleaning the PTFE surface without affecting the surface structure. The calculations using the PM3 and DFT methods were performed on single and multiple oligomers to simulate a wide variety of oxidation scenarios. Calculated work function results suggest that regardless of oxidation mechanism, e.g. -OH, =0 or a combination thereof, the experimentally observed levels of surface oxidation are unlikely to lead to a significant change in the electronic structure of PE and that its increased hydrophilic properties are the primary reason for the observed changes in its electrostatic behavior. The calculations for PTFE argue strongly against significant oxidation of that material, as confirmed by the XPS results.

Analysis of Wind Forces on Roof-Top Solar Panel

NASA Astrophysics Data System (ADS)

Panta, Yogendra; Kudav, Ganesh

2011-03-01

Structural loads on solar panels include forces due to high wind, gravity, thermal expansion, and earthquakes. International Building Code (IBC) and the American Society of Civil Engineers are two commonly used approaches in solar industries to address wind loads. Minimum Design Loads for Buildings and Other Structures (ASCE 7-02) can be used to calculate wind uplift loads on roof-mounted solar panels. The present study is primarily focused on 2D and 3D modeling with steady, and turbulent flow over an inclined solar panel on the flat based roof to predict the wind forces for designing wind management system. For the numerical simulation, 3-D incompressible flow with the standard k- ɛ was adopted and commercial CFD software ANSYS FLUENT was used. Results were then validated with wind tunnel experiments with a good agreement. Solar panels with various aspect ratios for various high wind speeds and angle of attacks were modeled and simulated in order to predict the wind loads in various scenarios. The present study concluded to reduce the strong wind uplift by designing a guide plate or a deflector before the panel. Acknowledgments to Northern States Metal Inc., OH (GK & YP) and School of Graduate Studies of YSU for RP & URC 2009-2010 (YP).

Vibrational Stark effect spectroscopy reveals complementary electrostatic fields created by protein-protein binding at the interface of Ras and Ral.

PubMed

Walker, David M; Hayes, Ellen C; Webb, Lauren J

2013-08-07

Electrostatic fields at the interface of the GTPase H-Ras (Ras) docked with the Ras binding domain of the protein Ral guanine nucleoside dissociation stimulator (Ral) were measured with vibrational Stark effect (VSE) spectroscopy. Nine residues on the surface of Ras that participate in the protein-protein interface were systematically mutated to cysteine and subsequently converted to cyanocysteine in order to introduce a nitrile VSE probe into the protein-protein interface. The absorption energy of the nitrile was measured both on the surface of Ras in its monomeric state, then after incubation with the Ras binding domain of Ral to form the docked complex. Boltzmann-weighted structural snapshots of the nitrile-labeled Ras protein were generated both in monomeric and docked configurations from molecular dynamics simulations using enhanced sampling of the cyanocysteine side chain's χ2 dihedral angle. These snapshots were used to determine that on average, most of the nitrile probes were aligned along the Ras surface, parallel to the Ras-Ral interface. The average solvent-accessible surface areas (SASA) of the cyanocysteine side chain were found to be <60 Å(2) for all measured residues, and was not significantly different whether the nitrile was on the surface of the Ras monomer or immersed in the docked complex. Changes in the absorption energy of the nitrile probe at nine positions along the Ras-Ral interface were compared to results of a previous study examining this interface with Ral-based probes, and found a pattern of low electrostatic field in the core of the interface surrounded by a ring of high electrostatic field around the perimeter of the interface. These data are used to rationalize several puzzling features of the Ras-Ral interface.

Vesicle Adhesion and Fusion Studied by Small-Angle X-Ray Scattering.

PubMed

Komorowski, Karlo; Salditt, Annalena; Xu, Yihui; Yavuz, Halenur; Brennich, Martha; Jahn, Reinhard; Salditt, Tim

2018-04-24

We have studied the adhesion state (also denoted by docking state) of lipid vesicles as induced by the divalent ions Ca 2+ or Mg 2+ at well-controlled ion concentration, lipid composition, and charge density. The bilayer structure and the interbilayer distance in the docking state were analyzed by small-angle x-ray scattering. A strong adhesion state was observed for DOPC:DOPS vesicles, indicating like-charge attraction resulting from ion correlations. The observed interbilayer separations of ∼1.6 nm agree quantitatively with the predictions of electrostatics in the strong coupling regime. Although this phenomenon was observed when mixing anionic and zwitterionic (or neutral) lipids, pure anionic membranes (DOPS) with highest charge density σ resulted in a direct phase transition to a multilamellar state, which must be accompanied by rupture and fusion of vesicles. To extend the structural assay toward protein-controlled docking and fusion, we have characterized reconstituted N-ethylmaleimide-sensitive factor attachment protein receptors in controlled proteoliposome suspensions by small-angle x-ray scattering. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Tuning of electrostatic vs. depletion interaction in deciding the phase behavior of nanoparticle-polymer system

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

Kumar, Sugam, E-mail: sugam@barc.gov.in; Aswal, V. K.; Kohlbrecher, J.

2015-06-24

Nanoparticle-polymer system interestingly show a re-entrant phase behavior where charge stabilized silica nanoparticles (phase I) undergo particle clustering (phase II) and then back to individual particles (phase I) as a function of polymer concentration. Such phase behavior arises as a result of dominance of various interactions (i) nanoparticle-nanoparticle electrostatic repulsion (ii) polymer induced attractive depletion between nanoparticles and (iii) polymer-polymer repulsion, at different concentration regimes. Small-angle neutron scattering (SANS) has been used to study the evolution of interaction during this re-entrant phase behavior of nanoparticles by contrast-marching the polymer. The SANS data have been modeled using a two-Yukawa potential accountingmore » for both attractive and repulsive parts of the interaction between nanoparticles. The degree of both of these parts has been separately tuned by varying the polymer concentration and ionic strength of the solution. Both of these parts are found to have long-range nature. At low polymer concentrations, the electrostatic repulsion dominates over the depletion attraction. The magnitude and the range of the depletion interaction increase with the polymer concentration leading to nanoparticle clustering. At higher polymer concentrations, the increased polymer-polymer repulsion reduces the strength of depletion leading to re-entrant phase behavior. The clusters formed under depletion attraction are found to have surface fractal morphology.« less

Global linear gyrokinetic simulations for LHD including collisions

NASA Astrophysics Data System (ADS)

Kauffmann, K.; Kleiber, R.; Hatzky, R.; Borchardt, M.

2010-11-01

The code EUTERPE uses a Particle-In-Cell (PIC) method to solve the gyrokinetic equation globally (full radius, full flux surface) for three-dimensional equilibria calculated with VMEC. Recently this code has been extended to include multiple kinetic species and electromagnetic effects. Additionally, a pitch-angle scattering operator has been implemented in order to include collisional effects in the simulation of instabilities and to be able to simulate neoclassical transport. As a first application of this extended code we study the effects of collisions on electrostatic ion-temperature-gradient (ITG) instabilities in LHD.

The kinetic energy spectrum of protons produced by the dissociative ionization of H2 by electron impact

NASA Technical Reports Server (NTRS)

Khakoo, M. A.; Srivastava, S. K.

1985-01-01

The kinetic energy spectra of protons resulting from the dissociative ionization of H2 by electron impact have been measured for electron impact energies from threshold (approximately 17 eV) to 160 eV at 90 deg and 30 deg detection angles, using a crossed-beam experimental arrangement. To check reliability, two separate proton energy analysis methods have been employed, i.e., a time-of-flight proton energy analysis and an electrostatic hemispherical energy analyzer. The present results are compared with previous measurements.

Relativistic nonlinear plasma waves in a magnetic field

NASA Technical Reports Server (NTRS)

Kennel, C. F.; Pellat, R.

1975-01-01

Five relativistic plane nonlinear waves were investigated: circularly polarized waves and electrostatic plasma oscillations propagating parallel to the magnetic field, relativistic Alfven waves, linearly polarized transverse waves propagating in zero magnetic field, and the relativistic analog of the extraordinary mode propagating at an arbitrary angle to the magnetic field. When the ions are driven relativistic, they behave like electrons, and the assumption of an 'electron-positron' plasma leads to equations which have the form of a one-dimensional potential well. The solutions indicate that a large-amplitude superluminous wave determines the average plasma properties.

Review of microscopic plasma processes of occurring during refilling of the plasmasphere

NASA Technical Reports Server (NTRS)

Singh, N.; Torr, D. G.

1988-01-01

Refilling of the plasmashere after geomagnetic storms involves both macroscopic and microscopic plasma processes. The latter types of processes facilitate the refilling by trapping the plasma in the flux tube and by thermalizing the interhemispheric flow. A review of studies on microscopic processes is presented. The primary focus in this review is on the processes when the density is low and the plasma is collisionless. The discussion includes electrostatic shock formation, pitch angle scatterring extended ion heating and localized ion heating in the equatorial region.

Effect of air deflectors on fan performance in tunnel-ventilated broiler houses with a dropped ceiling

USDA-ARS?s Scientific Manuscript database

Air velocity is a critical design parameter for modern commercial broiler houses, owing to the beneficial effects of increased cooling on live performance and thermal comfort in broiler chickens. As a result, design velocities have increased over the last 15 years and broiler growers have installed ...

Study on Micro Wind Generator System for Automobile

NASA Astrophysics Data System (ADS)

Fujimoto, Koji; Washizu, Shinsuke; Ichikawa, Tomohiko; Yukita, Kazuto; Goto, Yasuyuki; Ichiyanagi, Katsuhiro; Oshima, Takamitsu; Hayashi, Niichi; Tobi, Nobuo

This paper proposes the micro wind generator system for automobile. This proposes system is composed of the deflector, the micro windmill, the generator, and electric storage device. Then, the effectiveness is confirmed from an examination using air blower. Therefore, new energy can be expected to be obtained by installing this system in the truck.

Construction, alignment, and implementation of an acousto-optical deflector-based system for patterned uncaging with ultraviolet light.

PubMed

Civillico, Eugene F; Shoham, Shy; O'Connor, Daniel H; Sarkisov, Dmitry V; Wang, Samuel S-H

2012-08-01

The method of patterned photoactivation is a natural fit for the study of neuronal dendritic integration. Photoactivatable molecules that influence a wide range of extracellular and intracellular neurophysiological functions are available. The choice of photosensitive molecules depends on the research question and will influence the design of the experimental apparatus. An acousto-optical deflector (AOD)-based system can be used for rapid ultraviolet (UV) photolysis in arbitrary spatial and temporal patterns. Photolysis-activated "caged" diffusible molecules or newer light-sensitive membrane proteins can be used in this system. This protocol describes the addition of a UV beam for uncaging to a homebuilt two-photon microscope. The goal is to get UV light from the light source (laser) to the approximate center of the objective's back aperture, passing through a pair of perpendicularly oriented AODs along the way. The protocol also describes the fine alignment of the UV beam and the implementation of AOD-based beam steering. Performing the final alignment with the beam passing through the AODs will ensure that the system is optimized for the idiosyncrasies of the crystals.

STS-103 crew pose in front of Pad 39B

NASA Technical Reports Server (NTRS)

1999-01-01

During Terminal Countdown Demonstration Test (TDCT) activities at Launch Pad 39B, the STS-103 crew pose in front of the flame trench, which is situated underneath the Mobile Launcher Platform holding Space Shuttle Discovery. Standing left to right are Mission Specialists Claude Nicollier of Switzerland, who is with the European Space Agency (ESA), C. Michael Foale (Ph.D.), John M. Grunsfeld (Ph.D.), Pilot Scott J. Kelly, Commander Curtis L. Brown Jr., and Mission Specialists Jean-Frangois Clervoy of France, also with ESA, and Steven L. Smith. One of the solid rocket boosters and the external tank that are attached to Discovery can be seen in the photo. The flame trench is made of concrete and refractory brick, and contains an orbiter flame deflector on one side and solid rocket booster flame deflector on the other. The deflectors protect the flame trench floor and pad surface from the intense heat of launch. The TCDT provides the crew with emergency egress training, opportunities to inspect their mission payloads in the orbiter's payload bay, and simulated countdown exercises. STS-103 is a 'call-up' mission due to the need to replace and repair portions of the Hubble Space Telescope, including the gyroscopes that allow the telescope to point at stars, galaxies and planets. The STS-103 crew will be replacing a Fine Guidance Sensor, an older computer with a new enhanced model, an older data tape recorder with a solid-state digital recorder, a failed spare transmitter with a new one, and degraded insulation on the telescope with new thermal insulation. The crew will also install a Battery Voltage/Temperature Improvement Kit to protect the spacecraft batteries from overcharging and overheating when the telescope goes into a safe mode. Four EVA's are planned to make the necessary repairs and replacements on the telescope. The mission is targeted for launch Dec. 6 at 2:37 a.m. EST.

KSC-99pp1324

NASA Image and Video Library

1999-11-16

During Terminal Countdown Demonstration Test (TDCT) activities at Launch Pad 39B, the STS-103 crew pose in front of the flame trench, which is situated underneath the Mobile Launcher Platform holding Space Shuttle Discovery. Standing left to right are Mission Specialists Claude Nicollier of Switzerland, who is with the European Space Agency (ESA), C. Michael Foale (Ph.D.), John M. Grunsfeld (Ph.D.), Pilot Scott J. Kelly, Commander Curtis L. Brown Jr., and Mission Specialists Jean-François Clervoy of France, also with ESA, and Steven L. Smith. One of the solid rocket boosters and the external tank that are attached to Discovery can be seen in the photo. The flame trench is made of concrete and refractory brick, and contains an orbiter flame deflector on one side and solid rocket booster flame deflector on the other. The deflectors protect the flame trench floor and pad surface from the intense heat of launch. The TCDT provides the crew with emergency egress training, opportunities to inspect their mission payloads in the orbiter's payload bay, and simulated countdown exercises. STS-103 is a "call-up" mission due to the need to replace and repair portions of the Hubble Space Telescope, including the gyroscopes that allow the telescope to point at stars, galaxies and planets. The STS-103 crew will be replacing a Fine Guidance Sensor, an older computer with a new enhanced model, an older data tape recorder with a solid-state digital recorder, a failed spare transmitter with a new one, and degraded insulation on the telescope with new thermal insulation. The crew will also install a Battery Voltage/Temperature Improvement Kit to protect the spacecraft batteries from overcharging and overheating when the telescope goes into a safe mode. Four EVA's are planned to make the necessary repairs and replacements on the telescope. The mission is targeted for launch Dec. 6 at 2:37 a.m. EST

Angle-resolved effective potentials for disk-shaped molecules

NASA Astrophysics Data System (ADS)

Heinemann, Thomas; Palczynski, Karol; Dzubiella, Joachim; Klapp, Sabine H. L.

2014-12-01

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in more efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.

SOIMUMPs micromirror scanner and its application in laser line generator

NASA Astrophysics Data System (ADS)

Zuo, Hui; Nia, Farzad Hossein; He, Siyuan

2017-01-01

A SOIMUMPs 1-D rotation micromirror is presented. The micromirror is driven by electrostatic vertical comb-drive actuators to work at resonant mode to scan a laser beam. The residual stress in the metal film coated on the SOI device layer is used to generate vertical offset in the comb-drive actuators with the combs located far from the rotation axis to increase the torque. A concave lens is designed to put after the micromirror to amplify the laser beam scanning angle, as well as to compensate for the curvature of the micromirror. A micromirror-based scanning system is used to build a laser line generator with a continuously adjustable fan angle, which solves the limitation of a fixed fan angle in conventional laser line generators. Prototypes of the micromirror and the laser line generator are fabricated and measured. A driving circuit that can generate a high-voltage square wave driving signal with adjustable amplitude and frequency is designed. All the parts are integrated in a 44 mm×88 mm×44 mm box and powered with a single 5-V power supply. The optical scanning angle under 100 V with or without the concave lens is 27 deg and 12 deg, respectively, at a resonant frequency of 900 Hz.

Cross sections for ionization of tetrahydrofuran by protons at energies between 300 and 3000 keV

NASA Astrophysics Data System (ADS)

Wang, Mingjie; Rudek, Benedikt; Bennett, Daniel; de Vera, Pablo; Bug, Marion; Buhr, Ticia; Baek, Woon Yong; Hilgers, Gerhard; Rabus, Hans

2016-05-01

Double-differential cross sections for ionization of tetrahydrofuran by protons with energies from 300 to 3000 keV were measured at the Physikalisch-Technische Bundesanstalt ion accelerator facility. The electrons emitted at angles between 15∘ and 150∘ relative to the ion-beam direction were detected with an electrostatic hemispherical electron spectrometer. Single-differential and total ionization cross sections have been derived by integration. The experimental results are compared to the semiempirical Hansen-Kocbach-Stolterfoht model as well as to the recently reported method based on the dielectric formalism. The comparison to the latter showed good agreement with experimental data in a broad range of emission angles and energies of secondary electrons. The scaling property of ionization cross sections for tetrahydrofuran was also investigated. Compared to molecules of different size, the ionization cross sections of tetrahydrofuran were found to scale with the number of valence electrons at large impact parameters.

Analysis of a Chevron Beam Thermal Actuator

NASA Astrophysics Data System (ADS)

Joshi, Amey Sanjay; Mohammed, Hussain; Kulkarni, S. M., Dr.

2018-02-01

Thermal MEMS (Micro-Electro-Mechanical Systems) actuators and sensors have a wide range of applications. The chevron type thermal actuators comparatively show superior performance over other existing electrostatic and thermal actuators. This paper describes the design and analysis of chevron type thermal actuator. Here standard design of Chevron type thermal actuator is considered which comprises of proof mass at center and array of six beams of a uniform cross section of 3 3 microns and an initial angle of 5°. The thermal actuator was designed and analyzed using analytical and finite element method and the results were compared. The model was also analyzed for initial angles of 2.5° and 7.5°, and the results were compared with FEA model. The cross section of the beam was varied and the finite element analysis of all three models was compared to suggest the best suitable thermal actuator structure.

Electric potential distributions at the interface between plasmasheet clouds

NASA Technical Reports Server (NTRS)

Evans, D. S.; Roth, M.; Lemaire, J.

1987-01-01

At the interface between two plasma clouds with different densities, temperatures, and/or bulk velocities, there are large charge separation electric fields which can be modeled in the framework of a collisionless theory for tangential discontinuities. Two different classes of layers were identified: the first one corresponds to (stable) ion layers which are thicker than one ion Lamor radius; the second one corresponds to (unstable) electron layers which are only a few electron Larmor radii thick. It is suggested that these thin electron layers with large electric potential gradients (up to 400 mV/m) are the regions where large-amplitude electrostatic waves are spontaneously generated. These waves scatter the pitch angles of the ambient plasmasheet electron into the atmospheric loss cone. The unstable electron layers can therefore be considered as the seat of strong pitch angle scattering for the primary auroral electrons.

Nonlinear waves in electron-positron-ion plasmas including charge separation

NASA Astrophysics Data System (ADS)

Mugemana, A.; Moolla, S.; Lazarus, I. J.

2017-02-01

Nonlinear low-frequency electrostatic waves in a magnetized, three-component plasma consisting of hot electrons, hot positrons and warm ions have been investigated. The electrons and positrons are assumed to have Boltzmann density distributions while the motion of the ions are governed by fluid equations. The system is closed with the Poisson equation. This set of equations is numerically solved for the electric field. The effects of the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle are investigated. It is shown that depending on the driving electric field, ion temperature, positron density, ion drift, Mach number and propagation angle, the numerical solutions exhibit waveforms that are sinusoidal, sawtooth and spiky. The introduction of the Poisson equation increased the Mach number required to generate the waveforms but the driving electric field E 0 was reduced. The results are compared with satellite observations.

Sowing simulation tests of a pneumatic drill equipped with systems aimed at reducing the emission of abrasion dust from maize dressed seed.

PubMed

Biocca, Marcello; Conte, Elisa; Pulcini, Patrizio; Marinelli, Enzo; Pochi, Daniele

2011-01-01

The utilization of dressed seed for spring sowing is a widespread practice to control some pests with reduced doses of chemical products. However some insecticides employed in maize seed dressing, namely belonging to the neonicotinoid family and fipronil, have been claimed to play a role in the decline of honeybees (Apis mellifera L.). Pneumatic drills used in maize sowing are charged with contributing to the dispersion of the abrasion dust produced by dressed seeds, favoring the contamination of the honeybee habitat. Different devices similar to air deflectors have been introduced on pneumatic drills in order to reduce dust drift. During previous field tests carried out by the authors during recent years reduction of dust concentration both in the air and at soil surface has been shown as a consequence of their application. As field tests are affected by the variability of environmental parameters (namely wind speed and direction) the results are not always reliable, comparable and of a general validity. This paper refers to a sowing simulation test system in which pneumatic drills can be tested at a fixed point under controlled conditions of the main environmental parameters. In the test area, protected by external influences, artificial wind conditions are created by means of a fan. The drill, suitably placed in the test area, operates the seed distribution "sur place" by means of an electric engine connected to the drill's driving wheel. A 22.5 m long sampling area, leeward with respect to the drill position, has been identified. Along the sampling area a series of Petri dishes has been placed, with the aim of capturing the depositing dust and providing the concentration of the active ingredients (a.i.) at ground level. At the same time, three air samplers with PTFE diskette filters have been used for the detection of the a.i. The test system has been used for the test of a pneumatic drill, equipped with and without air deflectors, using maize seed dressed with four a. i. (imidacloprid, clothianidin, thiametoxam, fipronil). The results showed regularly decreasing of the concentrations as distance increased, both in the air and at ground level. Moreover, the difference determined by the adoption of the drift reducing device (air deflectors) resulted clear and it can be quantified at around 50 % of the a.i. amounts observed without deflectors. Finally, the paper proposes a data processing method that, from the values observed at fixed point, provides the theoretical a.i. concentration behavior that would occur in field, under the same conditions of wind speed and direction and working speed. The obtained results are coherent with previous field test.

Miniature low voltage beam systems producable by combined lithographies

NASA Astrophysics Data System (ADS)

Koops, Hans W. P.; Munro, Eric; Rouse, John; Kretz, Johannes; Rudolph, Michael; Weber, Markus; Dahm, Gerold

The project of a miniaturized vacuum microelectronic 100 GHz switch is described. It implies the development of a field emission electron gun as well as the investigation of miniaturized lenses and deflectors. Electrostatic elements are designed and developed for this application. Connector pads and wiring pattern are created by conventional electron beam lithography and a lift-off or etching process. Wire and other 3-dimensional structures are grown using electron beam induced deposition. This additive lithography allows to form electrodes and resistors of a preset conductivity. The scanning electron microscope features positioning the structures with nm precision. An unconventional lithography system is used that is capable of controlling the pixel dwell time within a shape with different time functions. With this special function 3-dimensional structures can be generated like free standing square shaped electrodes. The switch is built by computer controlled additive lithography avoiding assembly from parts. Lenses of micrometer dimensions were investigated with numerical electron optics programs computing the 3-dimensional potential and field distribution. From the extracted axial field distribution the electron optic characteristic parameters, like focal length, chromatic and spherical aberration, were calculated for various lens excitations. The analysis reveals that miniaturized optics for low energy electrons, as low as 30 eV, are diffraction limited. For a lens with 2 μm focal length, a chromatic aberration disc of 1 nm contributes to 12 nm diffraction disc. The spherical aberration blurs the probe by 0.02 nm, assuming an aperture of 0.01 rad. Employing hydrogen ions at 100 V, a probe diameter of 0.3 nm generated by chromatic aberration is possible. Miniaturized electron optical probe forming systems and imaging systems can be constructed with those lenses. Its application as lithography systems with massive parallel beams can be forseen.

Radionuclide measurements by accelerator mass spectrometry at Arizona

NASA Technical Reports Server (NTRS)

Jull, A. J. T.; Donahue, D. J.; Zabel, T. H.

1986-01-01

Over the past years, Tandem Accelerator Mass Spectrometry (TAMS) has become established as an important method for radionuclide analysis. In the Arizona system the accelerator is operated at a thermal voltage of 1.8MV for C-14 analysis, and 1.6 to 2MV for Be-10. Samples are inserted into a cesium sputter ion source in solid form. Negative ions sputtered from the target are accelerated to about 25kV, and the injection magnet selects ions of a particular mass. Ions of the 3+ charge state, having an energy of about 9MeV are selected by an electrostatic deflector, surviving ions pass through two magnets, where only ions of the desired mass-energy product are selected. The final detector is a combination ionization chamber to measure energy loss (and hence, Z), and a silicon surface-barrier detector which measures residual energy. After counting the trace iosotope for a fixed time, the injected ions are switched to the major isotope used for normalization. These ions are deflected into a Faraday cup after the first high-energy magnet. Repeated measurements of the isotope ratio of both sample and standards results in a measurement of the concentration of the radionuclide. Recent improvements in sample preparation for C-14 make preparation of high-beam current graphite targets directly from CO2 feasible. Except for some measurements of standards and backgrounds for Be-10 measurements to date have been on C-14. Although most results have been in archaeology and quaternary geology, studies have been expanded to include cosmogenic C-14 in meteorites. The data obtained so far tend to confirm the antiquity of Antarctic meteorites from the Allan Hills site. Data on three samples of Yamato meteorites gave terrestrial ages of between about 3 and 22 thousand years.

A general method for the derivation of the functional forms of the effective energy terms in coarse-grained energy functions of polymers. I. Backbone potentials of coarse-grained polypeptide chains

NASA Astrophysics Data System (ADS)

Sieradzan, Adam K.; Makowski, Mariusz; Augustynowicz, Antoni; Liwo, Adam

2017-03-01

A general and systematic method for the derivation of the functional expressions for the effective energy terms in coarse-grained force fields of polymer chains is proposed. The method is based on the expansion of the potential of mean force of the system studied in the cluster-cumulant series and expanding the all-atom energy in the Taylor series in the squares of interatomic distances about the squares of the distances between coarse-grained centers, to obtain approximate analytical expressions for the cluster cumulants. The primary degrees of freedom to average about are the angles for collective rotation of the atoms contained in the coarse-grained interaction sites about the respective virtual-bond axes. The approach has been applied to the revision of the virtual-bond-angle, virtual-bond-torsional, and backbone-local-and-electrostatic correlation potentials for the UNited RESidue (UNRES) model of polypeptide chains, demonstrating the strong dependence of the torsional and correlation potentials on virtual-bond angles, not considered in the current UNRES. The theoretical considerations are illustrated with the potentials calculated from the ab initio potential-energy surface of terminally blocked alanine by numerical integration and with the statistical potentials derived from known protein structures. The revised torsional potentials correctly indicate that virtual-bond angles close to 90° result in the preference for the turn and helical structures, while large virtual-bond angles result in the preference for polyproline II and extended backbone geometry. The revised correlation potentials correctly reproduce the preference for the formation of β-sheet structures for large values of virtual-bond angles and for the formation of α-helical structures for virtual-bond angles close to 90°.

A nontransferring dry adhesive with hierarchical polymer nanohairs.

PubMed

Jeong, Hoon Eui; Lee, Jin-Kwan; Kim, Hong Nam; Moon, Sang Heup; Suh, Kahp Y

2009-04-07

We present a simple yet robust method for fabricating angled, hierarchically patterned high-aspect-ratio polymer nanohairs to generate directionally sensitive dry adhesives. The slanted polymeric nanostructures were molded from an etched polySi substrate containing slanted nanoholes. An angled etching technique was developed to fabricate slanted nanoholes with flat tips by inserting an etch-stop layer of silicon dioxide. This unique etching method was equipped with a Faraday cage system to control the ion-incident angles in the conventional plasma etching system. The polymeric nanohairs were fabricated with tailored leaning angles, sizes, tip shapes, and hierarchical structures. As a result of controlled leaning angle and bulged flat top of the nanohairs, the replicated, slanted nanohairs showed excellent directional adhesion, exhibiting strong shear attachment (approximately 26 N/cm(2) in maximum) in the angled direction and easy detachment (approximately 2.2 N/cm(2)) in the opposite direction, with a hysteresis value of approximately 10. In addition to single scale nanohairs, monolithic, micro-nanoscale combined hierarchical hairs were also fabricated by using a 2-step UV-assisted molding technique. These hierarchical nanoscale patterns maintained their adhesive force even on a rough surface (roughness <20 microm) because of an increase in the contact area by the enhanced height of hierarchy, whereas simple nanohairs lost their adhesion strength. To demonstrate the potential applications of the adhesive patch, the dry adhesive was used to transport a large-area glass (47.5 x 37.5 cm(2), second-generation TFT-LCD glass), which could replace the current electrostatic transport/holding system with further optimization.

A nontransferring dry adhesive with hierarchical polymer nanohairs

PubMed Central

Jeong, Hoon Eui; Lee, Jin-Kwan; Kim, Hong Nam; Moon, Sang Heup; Suh, Kahp Y.

2009-01-01

We present a simple yet robust method for fabricating angled, hierarchically patterned high-aspect-ratio polymer nanohairs to generate directionally sensitive dry adhesives. The slanted polymeric nanostructures were molded from an etched polySi substrate containing slanted nanoholes. An angled etching technique was developed to fabricate slanted nanoholes with flat tips by inserting an etch-stop layer of silicon dioxide. This unique etching method was equipped with a Faraday cage system to control the ion-incident angles in the conventional plasma etching system. The polymeric nanohairs were fabricated with tailored leaning angles, sizes, tip shapes, and hierarchical structures. As a result of controlled leaning angle and bulged flat top of the nanohairs, the replicated, slanted nanohairs showed excellent directional adhesion, exhibiting strong shear attachment (≈26 N/cm2 in maximum) in the angled direction and easy detachment (≈2.2 N/cm2) in the opposite direction, with a hysteresis value of ≈10. In addition to single scale nanohairs, monolithic, micro-nanoscale combined hierarchical hairs were also fabricated by using a 2-step UV-assisted molding technique. These hierarchical nanoscale patterns maintained their adhesive force even on a rough surface (roughness <20 μm) because of an increase in the contact area by the enhanced height of hierarchy, whereas simple nanohairs lost their adhesion strength. To demonstrate the potential applications of the adhesive patch, the dry adhesive was used to transport a large-area glass (47.5 × 37.5 cm2, second-generation TFT-LCD glass), which could replace the current electrostatic transport/holding system with further optimization. PMID:19304801

PARTICLE ACCELERATOR

DOEpatents

Teng, L.C.

1960-01-19

ABS>A combination of two accelerators, a cyclotron and a ring-shaped accelerator which has a portion disposed tangentially to the cyclotron, is described. Means are provided to transfer particles from the cyclotron to the ring accelerator including a magnetic deflector within the cyclotron, a magnetic shield between the ring accelerator and the cyclotron, and a magnetic inflector within the ring accelerator.

The Effect of Interocular Contrast and Ocular Dominance on the Perception of Motion-in-Depth in 3-D Displays

DTIC Science & Technology

1981-08-01

Sokolov, 1911), by a plate containing a series of slits (Kanolt, 1918), or by lenticular sheets (Ives, 1930). A recently developed autostereoscopic...dioptic power and orientation were inserted in the stimulus deflector to correct the observer’s astigmatism . Spherical error, if 13 OBSERVER’S I

77 FR 20728 - Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery; Framework Adjustment 23

Federal Register 2010, 2011, 2012, 2013, 2014

2012-04-06

.... 111011616-2102-02] RIN 0648-BB51 Fisheries of the Northeastern United States; Atlantic Sea Scallop Fishery... Atlantic Sea Scallop Fishery Management Plan (Framework 23) and implements its measures. Framework 23 was... impacts on sea turtles through the requirement of a turtle deflector dredge; improve the effectiveness of...

Stennis Space Center Conducts Water Flow Test On The B-2 Test Stand

NASA Image and Video Library

2018-05-04

Stennis Space Center completed a water flow test of the refurbished B-2 Test Stand on May 4, 2018. This included both the deflector and the aspirator, individually and together. This test stand is being prepared for the testing of the Space Launch System's booster core, which will utilize four RS-25 rocket engines.

Eccentric superconducting RF cavity separator structure

DOEpatents

Aggus, John R.; Giordano, Salvatore T.; Halama, Henry J.

1976-01-01

Accelerator apparatus having an eccentric-shaped, iris-loaded deflecting cavity for an rf separator for a high energy high momentum, charged particle accelerator beam. In one embodiment, the deflector is superconducting, and the apparatus of this invention provides simplified machining and electron beam welding techniques. Model tests have shown that the electrical characteristics provide the desired mode splitting without adverse effects.

Electron optics with ballistic graphene junctions

NASA Astrophysics Data System (ADS)

Chen, Shaowen

Electrons transmitted across a ballistic semiconductor junction undergo refraction, analogous to light rays across an optical boundary. A pn junction theoretically provides the equivalent of a negative index medium, enabling novel electron optics such as negative refraction and perfect (Veselago) lensing. In graphene, the linear dispersion and zero-gap bandstructure admit highly transparent pn junctions by simple electrostatic gating, which cannot be achieved in conventional semiconductors. Robust demonstration of these effects, however, has not been forthcoming. Here we employ transverse magnetic focusing to probe propagation across an electrostatically defined graphene junction. We find perfect agreement with the predicted Snell's law for electrons, including observation of both positive and negative refraction. Resonant transmission across the pn junction provides a direct measurement of the angle dependent transmission coefficient, and we demonstrate good agreement with theory. Comparing experimental data with simulation reveals the crucial role played by the effective junction width, providing guidance for future device design. Efforts toward sharper pn junction and possibility of zero field Veselago lensing will also be discussed. This work is supported by the Semiconductor Research Corporations NRI Center for Institute for Nanoelectronics Discovery and Exploration (INDEX).

Structure/function implications in a dynamic complex of the intrinsically disordered Sic1 with the Cdc4 subunit of an SCF ubiquitin ligase

PubMed Central

Mittag, Tanja; Marsh, Joseph; Grishaev, Alexander; Orlicky, Stephen; Lin, Hong; Sicheri, Frank; Tyers, Mike; Forman-Kay, Julie D.

2010-01-01

Summary Intrinsically disordered proteins can form highly dynamic complexes with partner proteins. One such dynamic complex involves the intrinsically disordered Sic1 with its partner Cdc4 in regulation of yeast cell cycle progression. Phosphorylation of six N-terminal Sic1 sites leads to equilibrium engagement of each phosphorylation site with the primary binding pocket in Cdc4, the substrate recognition subunit of a ubiquitin ligase. ENSEMBLE calculations utilizing experimental NMR and small-angle x-ray scattering data reveal significant transient structure in both phosphorylation states of the isolated ensembles (Sic1 and pSic1) that modulates their electrostatic potential, suggesting a structural basis for the proposed strong contribution of electrostatics to binding. A structural model of the dynamic pSic1-Cdc4 complex demonstrates the spatial arrangements in the ubiquitin ligase complex. These results provide a physical picture of a protein that is predominantly disordered in both its free and bound states, enabling aspects of its structure/function relationship to be elucidated. PMID:20399186

Structural coloration of chitosan coated cellulose fabrics by electrostatic self-assembled poly (styrene-methyl methacrylate-acrylic acid) photonic crystals.

PubMed

Yavuz, Gönül; Zille, Andrea; Seventekin, Necdet; Souto, Antonio P

2018-08-01

The structural coloration of a chitosan-coated woven cotton fabric obtained by glutaraldehyde-stabilized deposition of electrostatic self-assembled monodisperse and spherically uniform (250 nm) poly (styrene-methyl methacrylate-acrylic acid) photonic crystal nanospheres (P(St-MMA-AA)) was investigated. Bright iridescent coatings displaying different colors in function of the viewing angle were obtained. The SEM, diffuse reflectance spectroscopy, TGA, DSC and FTIR analyses confirm the presence of structural color and the glutaraldehyde and chitosan ability to provide durable chemical bonding between cotton fabric and photonic crystal (PCs) coating with the highest degradation temperature and the lowest enthalpy. The coatings are characterized by a mixture of face-centered cubic and hexagonal close-packed arrays alternating random packing regions. For the first time a cost-efficient structural coloration with high washing and light fastness using self-assembled P(St-MMA-AA) photonic crystals was successfully developed onto woven cotton fabric using chitosan and/or glutaraldehyde as stabilizing agent opening new strategies for the development of dye-free coloration of textiles. Copyright © 2018 Elsevier Ltd. All rights reserved.

Low-kilovolt coherent electron diffractive imaging instrument based on a single-atom electron source

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

Lin, Chun-Yueh; Chang, Wei-Tse; Chen, Yi-Sheng

2016-03-15

In this work, a transmission-type, low-kilovolt coherent electron diffractive imaging instrument was constructed. It comprised a single-atom field emitter, a triple-element electrostatic lens, a sample holder, and a retractable delay line detector to record the diffraction patterns at different positions behind the sample. It was designed to image materials thinner than 3 nm. The authors analyzed the asymmetric triple-element electrostatic lens for focusing the electron beams and achieved a focused beam spot of 87 nm on the sample plane at the electron energy of 2 kV. High-angle coherent diffraction patterns of a suspended graphene sample corresponding to (0.62 Å){sup −1} were recorded. This workmore » demonstrated the potential of coherent diffractive imaging of thin two-dimensional materials, biological molecules, and nano-objects at a voltage between 1 and 10 kV. The ultimate goal of this instrument is to achieve atomic resolution of these materials with high contrast and little radiation damage.« less

Optical label-free and model-free probe of the surface potential of nanoscale and microscopic objects in aqueous solution

NASA Astrophysics Data System (ADS)

Lütgebaucks, Cornelis; Gonella, Grazia; Roke, Sylvie

2016-11-01

The electrostatic environment of aqueous systems is an essential ingredient for the function of any living system. To understand the electrostatic properties and their molecular foundation in soft, living, and three-dimensional systems, we developed a table-top model-free method to determine the surface potential of nano- and microscopic objects in aqueous solutions. Angle-resolved nonresonant second harmonic (SH) scattering measurements contain enough information to determine the surface potential unambiguously, without making assumptions on the structure of the interfacial region. The scattered SH light that is emitted from both the particle interface and the diffuse double layer can be detected in two different polarization states that have independent scattering patterns. The angular shape and intensity are determined by the surface potential and the second-order surface susceptibility. Calibrating the response with the SH intensity of bulk water, a single, unique surface potential value can be extracted. We demonstrate the method with 80 nm bare oil droplets in water and ˜50 nm dioleoylphosphatidylcholine (DOPC) and dioleoylphosphatidylserine (DOPS) liposomes at various ionic strengths.

High responsivity secondary ion energy analyzer

NASA Astrophysics Data System (ADS)

Belov, A. S.; Chermoshentsev, D. A.; Gavrilov, S. A.; Frolov, O. T.; Netchaeva, L. P.; Nikulin, E. S.; Zubets, V. N.

2018-05-01

The degree of space charge compensation of a 70 mA, 400 keV pulsed hydrogen ion beam has been measured with the use of an electrostatic energy analyzer of secondary ions. The large azimuthal angle of the analyzer enables a high responsivity, defined as the ratio of the slow secondary ion current emerging from the partially-compensated ion beam to the fast ion beam current. We measured 84% space charge compensation of the ion beam. The current from the slow ions and the rise time from the degree of space charge compensation were measured and compared with expected values.

Thrust vectoring systems

NASA Technical Reports Server (NTRS)

King, H. J.; Schnelker, D.; Ward, J. W.; Dulgeroff, C.; Vahrenkamp, R.

1972-01-01

The design, fabrication, and testing of thrust vectorable ion optical systems capable of controlling the thrust direction from both 5- and 30-cm diameter ion thrusters is described. Both systems are capable of greater than 10 deg thrust deflection in any azimuthal direction. The 5-cm system is electrostatic and hence has a short response time and minimal power consumption. It has recently been tested for more than 7500 hours on an operational thruster. The 30-cm system is mechanical, has a response time of the order of 1 min, and consumes less than 0.3% of the total system input power at full deflection angle.

Tensile-stressed microelectromechanical apparatus and micromirrors formed therefrom

DOEpatents

Fleming, James G [Albuquerque, NM

2006-05-16

A microelectromechanical (MEM) apparatus is disclosed which includes one or more tensile-stressed actuators that are coupled through flexures to a stage on a substrate. The tensile-stressed actuators, which can be formed from tensile-stressed tungsten or silicon nitride, initially raise the stage above the substrate without any applied electrical voltage, and can then be used to control the height or tilt angle of the stage. An electrostatic actuator can also be used in combination with each tensile-stressed actuator. The MEM apparatus has applications for forming piston micromirrors or tiltable micromirrors and independently addressable arrays of such devices.

Spatial, spectral and statistical properties of the electrostatic fluctuations and measurements of the scattering of the beam in a strongly turbulent plasma

NASA Astrophysics Data System (ADS)

McFarland, Michael Duane

The purpose of this investigation is to measure the spatial, spectral and statistical properties of the high (/omega/ ~/ ω pe) and low (/omega/ ~/ ωpi) frequency electrostatic fluctuations in an unmagnetized, statistically stable, beam-driven, strongly turbulent plasma and compare the results to theoretical predictions. In addition the scattering of the electron beam in both angle and energy is measured and compared to theory. This study is motivated by the recent advances in statistical theories of strong Langmuir turbulence and the glaring lack of confirmatory experimental data. With the advent of modern computers and electronics, enormous data sets are now routinely digitize and subjected to sophisticated statistical and spectral analysis. These methods, along with traditional procedures and an innovative technique known as a 'conditional trigger', are used to extract ensemble averages from the turbulent system for comparison with the theoretical models. It is found that the high-frequency fluctuations consist of low-level wave activity /langle W/rangle/ ~/ 10-2 - 103 punctuated by semi-periodic, intense, spiky field events /langle W/rangle/ ~/ 1, where /langle W/rangle is the normalized intensity. The low- level wave activity has a spectral spread Δ k/k/ ~/ /Delta/omega//omega/ ~ 30%, dispersion relation v beam/ ~/ /omega/k, and correlation length lc/ /approx/ 3λES, where λES is the electrostatic wavelength, and shows evidence of low-intensity parametric decay products. The intense field events, on the other hand, show little correlation for l/ >/ λES, have a full-width-at-half-maximum of 1 f/ < 40/ λ D, where λ D is the Debye length, and are non-propagating. The statistical properties of the fluctuations compares well with the predictions of the two-component model of strong Langmuir turbulence. In addition, freely traveling waves, 'free modes', are observed to be produced by the localized wave structures for the first time. The peak of the low frequency fluctuations is found to scale inversely with the average time between collapse events. The magnitude of the low-frequency fluctuations Δ n/n is compared to the two-component model of strong Langmuir turbulence. It is found that /n2/ /propto/ < W>β where β ~/ 1.3 for the experiment and is predicted to be β ~/ 1.98 by the model. The scattering of the electron beam in angle for a typical wave intensity level /langle W/rangle/ ~/ 0.04 is Θ ~/ 3o, and in energy is Δ U/ ~/ 25 eV for a 400 eV beam. The scattering of the beam in both angle and energy is found to agree well with theory.

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

Heinemann, Thomas, E-mail: thomas.heinemann@tu-berlin.de; Klapp, Sabine H. L., E-mail: klapp@physik.tu-berlin.de; Palczynski, Karol, E-mail: karol.palczynski@helmholtz-berlin.de

We present an approach for calculating coarse-grained angle-resolved effective pair potentials for uniaxial molecules. For integrating out the intramolecular degrees of freedom we apply umbrella sampling and steered dynamics techniques in atomistically-resolved molecular dynamics (MD) computer simulations. Throughout this study we focus on disk-like molecules such as coronene. To develop the methods we focus on integrating out the van der Waals and intramolecular interactions, while electrostatic charge contributions are neglected. The resulting coarse-grained pair potential reveals a strong temperature and angle dependence. In the next step we fit the numerical data with various Gay-Berne-like potentials to be used in moremore » efficient simulations on larger scales. The quality of the resulting coarse-grained results is evaluated by comparing their pair and many-body structure as well as some thermodynamic quantities self-consistently to the outcome of atomistic MD simulations of many-particle systems. We find that angle-resolved potentials are essential not only to accurately describe crystal structures but also for fluid systems where simple isotropic potentials start to fail already for low to moderate packing fractions. Further, in describing these states it is crucial to take into account the pronounced temperature dependence arising in selected pair configurations due to bending fluctuations.« less

Theory of a cylindrical probe in a collisionless magnetoplasma

NASA Technical Reports Server (NTRS)

Laframboise, J. G.; Rubinstein, J.

1976-01-01

A theory is presented for a cylindrical electrostatic probe in a collisionless plasma in the case where the probe axis is inclined at an angle to a uniform magnetic field. The theory is applicable to electron collection, and under more restrictive conditions, to ion collection. For a probe at space potential, the theory is exact in the limit where probe radius is much less than Debye length. At attracting probe potentials, the theory yields an upper bound and an adiabatic limit for current collection. At repelling probe potentials, it provides a lower bound. The theory is valid if the ratios of probe radius to Debye length and probe radius to mean gyroradius are not simultaneously large enough to produce extrema in the probe sheath potential. The numerical current calculations are based on the approximation that particle orbits are helices near the probe, together with the use of kinetic theory to relate velocity distributions near the probe to those far from it. Probe characteristics are presented for inclination angles from 0 to 90 deg and for probe-radius mean-gyroradius ratios from 0.1 to infinity. For an angle of 0 deg, the end-effect current is calculated separately.

A Low Cost Brush Deflection System for Bank Stabilization and Revegetation

Treesearch

Mary Elizabeth Meyer

1989-01-01

A series of brush deflectors were installed along an eroding, undercut streambank on Lindo Channel in Chico, California. Pieces of brush were wired to sets of metal fenceposts driven into the bank perpendicular to stream flow and at strategic points upstream. Dormant cuttings of riparian plants were added for revegetation and long-term bank protection. To date (two...

Saturn Apollo Program

NASA Image and Video Library

1967-07-28

This photograph depicts a view of the test firing of all five F-1 engines for the Saturn V S-IC test stage at the Marshall Space Flight Center. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon. Operating at maximum power, all five of the engines produced 7,500,000 pounds of thrust. The S-IC Static Test Stand was designed and constructed with the strength of hundreds of tons of steel and cement, planted down to bedrock 40 feet below ground level, and was required to hold down the brute force of the 7,500,000-pound thrust. The structure was topped by a crane with a 135-foot boom. With the boom in the up position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. When the Saturn V S-IC first stage was placed upright in the stand , the five F-1 engine nozzles pointed downward on a 1,900-ton, water-cooled deflector. To prevent melting damage, water was sprayed through small holes in the deflector at the rate 320,000 gallons per minutes

Saturn Apollo Program

NASA Image and Video Library

1965-05-01

This photograph depicts a view of the test firing of all five F-1 engines for the Saturn V S-IC test stage at the Marshall Space Flight Center. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon. Operating at maximum power, all five of the engines produced 7,500,000 pounds of thrust. The S-IC Static Test Stand was designed and constructed with the strength of hundreds of tons of steel and cement, planted down to bedrock 40 feet below ground level, and was required to hold down the brute force of the 7,500,000-pound thrust. The structure was topped by a crane with a 135-foot boom. With the boom in the up position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. When the Saturn V S-IC first stage was placed upright in the stand , the five F-1 engine nozzles pointed downward on a 1,900-ton, water-cooled deflector. To prevent melting damage, water was sprayed through small holes in the deflector at the rate 320,000 gallons per minutes.

Computational Plume Modeling of COnceptual ARES Vehicle Stage Tests

NASA Technical Reports Server (NTRS)

Allgood, Daniel C.; Ahuja, Vineet

2007-01-01

The plume-induced environment of a conceptual ARES V vehicle stage test at the NASA Stennis Space Center (NASA-SSC) was modeled using computational fluid dynamics (CFD). A full-scale multi-element grid was generated for the NASA-SSC B-2 test stand with the ARES V stage being located in a proposed off-center forward position. The plume produced by the ARES V main power plant (cluster of five RS-68 LOX/LH2 engines) was simulated using a multi-element flow solver - CRUNCH. The primary objective of this work was to obtain a fundamental understanding of the ARES V plume and its impingement characteristics on the B-2 flame-deflector. The location, size and shape of the impingement region were quantified along with the un-cooled deflector wall pressures, temperatures and incident heating rates. Issues with the proposed tests were identified and several of these addressed using the CFD methodology. The final results of this modeling effort will provide useful data and boundary conditions in upcoming engineering studies that are directed towards determining the required facility modifications for ensuring safe and reliable stage testing in support of the Constellation Program.

Physical and Vegetative Characteristics of a Newly Constructed Wetland and Modified Stream Reach, Tredyffrin Township, Chester County, Pennsylvania, 2000-2006

USGS Publications Warehouse

Chaplin, Jeffrey J.; White, Kirk E.; Olson, Leif E.

2009-01-01

To compensate for authorized disturbance of naturally occurring wetlands and streams during roadway improvements to U.S. Highway 202 in Chester and Montgomery Counties, Pa., the Pennsylvania Department of Transportation (PennDOT) constructed 0.42 acre of emergent wetland and 0.94 acre of scrub-shrub/forested wetland and modified sections of a 1,600-foot reach of Valley Creek with woody riparian plantings and streambank-stabilization structures (including rock deflectors). In accordance with project permits and additional guidance issued by the U.S. Army Corps of Engineers, the U.S. Geological Survey (USGS), in cooperation with PennDOT, collected data from 2000 through 2006 to quantify changes in 1) the vegetation, soils, and extent of emergent and scrub-shrub/forested parts of the constructed wetland, 2) the profile, dimension, and substrate in the vicinity of rock deflectors placed at two locations within the modified stream reach, and 3) the woody vegetation within the planted riparian buffer. The data for this investigation were collected using an approach adapted from previous investigations so that technology and findings may be more easily transferred among projects with similar objectives. Areal cover by planted and non-planted vegetation growing within the emergent and scrub-shrub/forested parts of the constructed wetland exceeded 85 percent at the end of each growing season, a criterion in special condition 25c in the U.S. Army Corps of Engineers project permit. Areal cover of vegetation in emergent and scrub-shrub/forested parts of the constructed wetland exceeded 100 percent in all but one growing season. Frequent and long-lasting soil saturation favored obligate-wetland species like Typha latifolia (broadleaf cattail) and Scirpus validus (great bulrush), both of which maintained dominance in the emergent wetland throughout the study (percent cover was 20 and 78 percent, respectively, in 2006). Echinocloa crusgalli (barnyard grass), an annual invasive from Eurasia, initially established in the newly disturbed soils of the scrub-shrub/forested wetland (areal cover was 56 percent in 2000), but by 2002, E. crusgalli was not growing in any sample plots and other species including Agrostis stolonifera (creeping bent grass), Festuca rubra (red fescue), Cornus spp. (dogwood species), and Salix nigra (black willow) were becoming more common. Sal. nigra contributed 30-percent cover in the scrub-shrub/forested wetland part by fall 2003. Rapid colonization of this species in subsequent years increased annual cover through 2006, when 15- to 25-foot tall Sal. nigra trees dominated the tree/shrub stratum (48 percent of the areal cover in 2006). The understory of the scrub-shrub/forested wetland was mostly shaded because of the canopy of Sal. nigra trees. Herbaceous species growing under and near the margins of the canopy included Ag. stolonifera and Ty. latifolia (29- and 23-percent areal cover, respectively). Flows in Valley Creek are responsible for transporting sediment and shaping the channel. Annual mean streamflow during the period the modified stream reach was monitored ranged from 15.2 cubic feet per second (ft3/s) in the 2002 water year to 53.0 ft3/s in the 2004 water year. This is a range of about 55 percent lower to 58 percent higher than the annual mean streamflow for the period of record. Despite the variability in streamflow, longitudinal profiles surveyed near rock deflectors in two short (100-foot) reaches within the modified stream reach maintained a constant slope throughout the monitoring period, most likely because of the presence of bedrock control. Cross-section geometry in the upstream reach was virtually unchanged during the monitoring period but 10 feet of bank migration was measured downstream, leaving the rock deflectors in mid-stream. As indicated by the change in channel morphology at the downstream reach, it is apparent that the rock deflectors were ineffective at adequately protecting the bank

Generation of Highly Oblique Lower Band Chorus Via Nonlinear Three-Wave Resonance

DOE PAGES

Fu, Xiangrong; Gary, Stephen Peter; Reeves, Geoffrey D.; ...

2017-09-05

Chorus in the inner magnetosphere has been observed frequently at geomagnetically active times, typically exhibiting a two-band structure with a quasi-parallel lower band and an upper band with a broad range of wave normal angles. But recent observations by Van Allen Probes confirm another type of lower band chorus, which has a large wave normal angle close to the resonance cone angle. It has been proposed that these waves could be generated by a low-energy beam-like electron component or by temperature anisotropy of keV electrons in the presence of a low-energy plateau-like electron component. This paper, however, presents an alternativemore » mechanism for generation of this highly oblique lower band chorus. Through a nonlinear three-wave resonance, a quasi-parallel lower band chorus wave can interact with a mildly oblique upper band chorus wave, producing a highly oblique quasi-electrostatic lower band chorus wave. This theoretical analysis is confirmed by 2-D electromagnetic particle-in-cell simulations. Furthermore, as the newly generated waves propagate away from the equator, their wave normal angle can further increase and they are able to scatter low-energy electrons to form a plateau-like structure in the parallel velocity distribution. As a result, the three-wave resonance mechanism may also explain the generation of quasi-parallel upper band chorus which has also been observed in the magnetosphere.« less

Aerodynamic studies of the beam bridge

NASA Astrophysics Data System (ADS)

Salenko, S. D.; Obukhovskiy, A. D.; Gosteev, Yu. A.

2017-10-01

The paper investigates the aeroelastic oscillations in the wind flow of the span structure (SS) of the beam bridge at the stage of mounting. Experiments with the SS sectional model and numerical calculations showed that at the stage of mounting the structure can be subject to two types of aeroelastic vibrations: vortex induced vibration and galloping. The main contribution to the excitation of oscillations is made by the section of the SS without cantilever plates. For this section site, the dominant frequency of the vortex shedding corresponds to the Strouhal number Sh≈0,067. In the process of wind tunnel simulation of dynamically similar model, its bending vibrations with an amplitude of about 1.5 m were observed in terms of the full-scale conditions, and the zones of wind resonance and galloping were closed. The ambiguity of the effect on the SS aeroelastic oscillations of the flow sideslip angle is found. To eliminate the aeroelastic vibrations which are a characteristic of this SS, several variants of dampers in the form of deflectors and flat step plate were investigated. As a result of optimization of the damper parameters, the amplitude of the aeroelastic oscillations of the full-scale SS has been reduced to values less than ˜ 0.1 m in the entire range of possible wind speeds up to 24 m/s at all stages of mounting.

Sound Radiation from a Supersonic Jet Passing Through a Partially Open Exhaust Duct

NASA Technical Reports Server (NTRS)

Kandula, Max

2011-01-01

The radiation of sound from a perfectly expanded Mach 2.5 cold supersonic jet of 25.4 mm exit diameter flowing through a partially open rigid-walled duct with an upstream i-deflector has been studied experimentally. In the experiments, the nozzle is mounted vertically, with the nozzle exit plane at a height of 73 jet diameters above ground level. Relative to the nozzle exit plane (NEP), the location of the duct inlet is varied at 10, 5, and -1 jet diameters. Far-field sound pressure levels were obtained at 54 jet diameters above ground with the aid of acoustic sensors equally spaced around a circular arc of radius equal to 80 jet diameters from the jet axis. Data on the jet acoustic field for the partially open duct were obtained and compared with those with a free jet and with a closed duct. The results suggest that for the partially open duct the overall sound pressure level (OASPL) decreases as the distance between the NEP and the duct inlet plane decreases, while the opposite trend is observed for the closed duct. It is also concluded that the observed peak frequency in the partially open duct increases above the free jet value as the angle from the duct axis is increased, and as the duct inlet plane becomes closer to the NEP.

Influence of surfactants in forced dynamic dewetting.

PubMed

Henrich, Franziska; Fell, Daniela; Truszkowska, Dorota; Weirich, Marcel; Anyfantakis, Manos; Nguyen, Thi-Huong; Wagner, Manfred; Auernhammer, Günter K; Butt, Hans-Jürgen

2016-09-20

In this work we show that the forced dynamic dewetting of surfactant solutions depends sensitively on the surfactant concentration. To measure this effect, a hydrophobic rotating cylinder was horizontally half immersed in aqueous surfactant solutions. Dynamic contact angles were measured optically by extrapolating the contour of the meniscus to the contact line. Anionic (sodium 1-decanesulfonate, S-1DeS), cationic (cetyl trimethylammonium bromide, CTAB) and nonionic surfactants (C 4 E 1 , C 8 E 3 and C 12 E 5 ) with critical micelle concentrations (CMCs) spanning four orders of magnitude were used. The receding contact angle in water decreased with increasing velocity. This decrease was strongly enhanced when adding surfactant, even at surfactant concentrations of 10% of the critical micelle concentration. Plots of the receding contact angle-versus-velocity almost superimpose when being plotted at the same relative concentration (concentration/CMC). Thus the rescaled concentration is the dominating property for dynamic dewetting. The charge of the surfactants did not play a role, thus excluding electrostatic effects. The change in contact angle can be interpreted by local surface tension gradients, i.e. Marangoni stresses, close to the three-phase contact line. The decrease of dynamic contact angles with velocity follows two regimes. Despite the existence of Marangoni stresses close to the contact line, for a dewetting velocity above 1-10 mm s -1 the hydrodynamic theory is able to describe the experimental results for all surfactant concentrations. At slower velocities an additional steep decrease of the contact angle with velocity was observed. Particle tracking velocimetry showed that the flow profiles do not differ with and without surfactant on a scales >100 μm.

Properties of the electrostatically driven helical plasma state

NASA Astrophysics Data System (ADS)

Akçay, Cihan; Finn, John M.; Nebel, Richard A.; Barnes, Daniel C.; Martin, Neal

2018-02-01

A novel plasma state has been found [Akçay et al., Phys. Plasmas 24, 052503 (2017)] in the presence of a uniform applied axial magnetic field in periodic cylindrical geometry. This state is driven by external electrostatic fields provided by helical electrodes with a (m =1 ,n =1 ) (helical) symmetry where m and n represent the poloidal and axial harmonics. The resulting plasma is a function of the cylinder radius r

Ice Harbor Spillway Dissolved Gas Field Studies: Before and After Spillway Deflectors

DTIC Science & Technology

2016-07-01

Executive Summary The operation of spillways on the Columbia and Snake Rivers causes the absorption of atmospheric gases (chiefly nitrogen and oxygen) to...chiefly nitrogen and oxygen) to super- saturated levels. For many operations, the total dissolved gas (TDG) levels exceed state and National...powerhouse releases. However, these mass- balance calculations conclusively show that a substantial portion of the powerhouse discharge becomes entrained

23 CFR Appendix D to Part 658 - Devices That Are Excluded From Measurement of the Length or Width of a Commercial Motor Vehicle

Code of Federal Regulations, 2010 CFR

2010-04-01

... or Width of a Commercial Motor Vehicle D Appendix D to Part 658 Highways FEDERAL HIGHWAY... DESIGNATIONS-LENGTH, WIDTH AND WEIGHT LIMITATIONS Pt. 658, App. D Appendix D to Part 658—Devices That Are... operations; (c) Aerodynamic devices, air deflector; (d) Air compressor; (e) Certificate holder (manifest box...

Measurement of Systematic Error Effects for a Sensitive Storage Ring EDM Polarimeter

NASA Astrophysics Data System (ADS)

Imig, Astrid; Stephenson, Edward

2009-10-01

The Storage Ring EDM Collaboration was using the Cooler Synchrotron (COSY) and the EDDA detector at the Forschungszentrum J"ulich to explore systematic errors in very sensitive storage-ring polarization measurements. Polarized deuterons of 235 MeV were used. The analyzer target was a block of 17 mm thick carbon placed close to the beam so that white noise applied to upstream electrostatic plates increases the vertical phase space of the beam, allowing deuterons to strike the front face of the block. For a detector acceptance that covers laboratory angles larger than 9 ^o, the efficiency for particles to scatter into the polarimeter detectors was about 0.1% (all directions) and the vector analyzing power was about 0.2. Measurements were made of the sensitivity of the polarization measurement to beam position and angle. Both vector and tensor asymmetries were measured using beams with both vector and tensor polarization. Effects were seen that depend upon both the beam geometry and the data rate in the detectors.

Early nucleation events in the polymerization of actin, probed by time-resolved small-angle x-ray scattering

PubMed Central

Oda, Toshiro; Aihara, Tomoki; Wakabayashi, Katsuzo

2016-01-01

Nucleators generating new F-actin filaments play important roles in cell activities. Detailed information concerning the events involved in nucleation of actin alone in vitro is fundamental to understanding these processes, but such information has been hard to come by. We addressed the early process of salt-induced polymerization of actin using the time-resolved synchrotron small-angle X-ray scattering (SAXS). Actin molecules in low salt solution maintain a monomeric state by an electrostatic repulsive force between molecules. On mixing with salts, the repulsive force was rapidly screened, causing an immediate formation of many of non-polymerizable dimers. SAXS kinetic analysis revealed that tetramerization gives the highest energetic barrier to further polymerization, and the major nucleation is the formation of helical tetramers. Filaments start to grow rapidly with the formation of pentamers. These findings suggest an acceleration mechanism of actin assembly by a variety of nucleators in cells. PMID:27775032

Effect of pH on the adsorption of dodecylamine on montmorillonite: Insights from experiments and molecular dynamics simulations

NASA Astrophysics Data System (ADS)

Peng, Chenliang; Min, Fanfei; Liu, Lingyun

2017-12-01

The hydrophobic aggregation in cationic surfactant suspension is an effective method to enhance the dewatering of clay-rich tailing. The solution pH can affect the adsorption behavior of cationic surfactant on clay mineral. The effect of pH on the adsorption of dodecylamine (DDA) on montmorillonite was investigated by the sedimentation test and the characterization of flocs images, contact angle, adsorption quantity, and fourier transform infrared (FTIR) spectroscopy, as well as molecular dynamics (MD) simulation. It was found that DDA ions were adsorbed on montmorillonite basal surfaces mainly by physical adsorption, including the electrostatic attraction and hydrogen bonding. A certain number of neutral DDA molecules can favor the adsorption of DDA. At pH around 8, the effect of hydrophobic modification was the best because DDA molecules and ions form compact and well-organized monolayer. The MD simulation results were in good agreement with that of contact angle, adsorption quantity and FTIR.

Carbodiimide-mediated immobilization of acidic biomolecules on reversed-charge zwitterionic sensor chip surfaces.

PubMed

Risse, Fabian; Gedig, Erk T; Gutmann, Jochen S

2018-04-30

The carbodiimide-mediated amine coupling of protein ligands to sensor chips coated with anionic polycarboxylate hydrogels, such as carboxymethyl dextran, is the predominant covalent immobilization procedure utilized in optical biosensors, namely surface plasmon resonance (SPR) biosensors. Usually, electrostatic interactions at a slightly acidic pH and low ionic strength are employed to efficiently accumulate neutral and basic ligands on the chip surface, which are then covalently coupled by surface-bound active N-hydroxysuccinimide (NHS) esters. Unfortunately, this approach is not suitable for acidic proteins or other ligands with low isoelectric points (IEPs), such as nucleic acids, because the charge density of the polycarboxylates is greatly reduced at acidic pH or because electrostatic attraction cannot be achieved. To overcome these drawbacks, we have established a charge-reversal approach that allows the preconcentration of acidic proteins above their IEPs. A precisely controlled amount of tertiary amines is applied to reverse the previous anionic surface charge while maintaining carbodiimide compatibility with future protein immobilization. The mechanism of this reversed-charge immobilization approach was demonstrated employing protein A as a model protein and using attenuated total reflectance Fourier transform infrared spectroscopy, dynamic contact angle measurements, colorimetric quantification, and SPR analysis to characterize surface derivatization. Furthermore, even though it had previously proven impossible to preconcentrate DNA electrostatically and to covalently couple it to polyanionic chip surfaces, we demonstrated that our approach allowed DNA to be preconcentrated and immobilized in good yields. Graphical abstract Principle of the covalent immobilization of acidic ligands on reversed-charge zwitterionic sensor chip surfaces.

A rocket-borne data-manipulation experiment using a microprocessor

NASA Technical Reports Server (NTRS)

Davis, L. L.; Smith, L. G.; Voss, H. D.

1979-01-01

The development of a data-manipulation experiment using a Z-80 microprocessor is described. The instrumentation is included in the payloads of two Nike Apache sounding rockets used in an investigation of energetic particle fluxes. The data from an array of solid-state detectors and an electrostatic analyzer is processed to give the energy spectrum as a function of pitch angle. The experiment performed well in its first flight test: Nike Apache 14.543 was launched from Wallops Island at 2315 EST on 19 June 1978. The system was designed to be easily adaptable to other data-manipulation requirements and some suggestions for further development are included.

Medium-energy particle experiments—electron analyzer (MEP-e) for the exploration of energization and radiation in geospace (ERG) mission

NASA Astrophysics Data System (ADS)

Kasahara, Satoshi; Yokota, Shoichiro; Mitani, Takefumi; Asamura, Kazushi; Hirahara, Masafumi; Shibano, Yasuko; Takashima, Takeshi

2018-05-01

The medium-energy particle experiments—electron analyzer onboard the exploration of energization and radiation in geospace spacecraft measures the energy and direction of each incoming electron in the energy range of 7-87 keV. The sensor covers a 2 π-radian disklike field of view with 16 detectors, and the full solid angle coverage is achieved through the spacecraft's spin motion. The electron energy is independently measured by both an electrostatic analyzer and avalanche photodiodes, enabling significant background reduction. We describe the technical approach, data output, and examples of initial observations.[Figure not available: see fulltext.

Nuclear nanoprobe development for visualization of three-dimensional nanostructures

NASA Astrophysics Data System (ADS)

Takai, M.; Abo, S.; Wakaya, F.; Kikuchi, T.; Sawaragi, H.

2007-08-01

A nanoprobe system, having a liquid metal ion source with a compact electrostatic accelerating column with a maximum accelerating voltage of 200 kV and an ultra high vacuum chamber, giving rise to the enhanced sensitivity because of the large scattering cross-section, has been designed for analysis of nanostructures. The focusing performance of the probes down to 10 nm was measured and compared with the simulation. Time-of-flight (TOF) RBS using a micro channel plate (MCP) further increases the sensitivity because of the increase in acceptance angle, which realizes the visualization of nanostructures with a beam spot diameter less than 10 nm with less probe damage.

Microelectromechanical mirrors and electrically-programmable diffraction gratings based on two-stage actuation

DOEpatents

Allen, James J.; Sinclair, Michael B.; Dohner, Jeffrey L.

2005-11-22

A microelectromechanical (MEM) device for redirecting incident light is disclosed. The MEM device utilizes a pair of electrostatic actuators formed one above the other from different stacked and interconnected layers of polysilicon to move or tilt an overlying light-reflective plate (i.e. a mirror) to provide a reflected component of the incident light which can be shifted in phase or propagation angle. The MEM device, which utilizes leveraged bending to provide a relatively-large vertical displacement up to several microns for the light-reflective plate, has applications for forming an electrically-programmable diffraction grating (i.e. a polychromator) or a micromirror array.

An effect of nuclear electric quadrupole moments in thermonuclear fusion plasmas

NASA Technical Reports Server (NTRS)

De, B. R.; Srnka, L. J.

1978-01-01

Consideration of the nuclear electric quadrupole terms in the expression for the fusion Coulomb barrier suggests that this electrostatic barrier may be substantially modified from that calculated under the usual plasma assumption that the nuclei are electric monopoles. This effect is a result of the nonspherical potential shape and the spatial quantization of the nuclear spins of the fully stripped ions in the presence of a magnetic field. For monopole-quadrupole fuel cycles like p-B-11, the fusion cross-section may be substantially increased at low energies if the protons are injected at a small angle relative to the confining magnetic field.

Control of Flowing Liquid Films By Electrostatic Fields in Space

NASA Technical Reports Server (NTRS)

Bankoff, S. George; Miksis, Michael J.; Kim, Hyo

1996-01-01

A novel type of lightweight space radiator has been proposed which employs internal electrostatic fields to stop coolant leaks from punctures caused by micrometeorites or space debris. Extensive calculations have indicated the feasibility of leak stoppage without film destabilization for both stationary and rotating designs. Solutions of the evolution equation for a liquid-metal film on an inclined plate, using lubrication theory for low Reynolds numbers, Karman-Pohlhausen quadratic velocity profiles for higher Reynolds numbers, and a direct numerical solution are shown. For verification an earth-based falling-film experiment on a precisely-vertical wall with controllable vacuum on either side of a small puncture is proposed. The pressure difference required to start and to stop the leak, in the presence and absence of a strong electric field, will be measured and compared with calculations. Various parameters, such as field strength, film Reynolds number, contact angle, and hole diameter will be examined. A theoretical analysis will be made of the case where the electrode is close enough to the film surface that the electric field equation and the surface dynamics equations are coupled. Preflight design calculations will be made in order to transfer the modified equipment to a flight experiment.

The electron-cyclotron maser instability as a source of plasma radiation. [Solar radio bursts

NASA Technical Reports Server (NTRS)

Winglee, R. M.; Dulk, G. A.

1986-01-01

The generation of continuum bursts from the sun at dm and m wavelengths (in particular, type IV bursts) via the electron-cyclotron-maser instability is examined. The maser instability can be driven by an electron distribution with either a loss-cone anisotropy or a peak at large pitch angles. For omega(p)/Omega(e) much greater than 1, the maser emission is produced by electrons interacting through a harmonic (cyclotron) resonance and is electrostatic, being in the upper hybrid mode at frequencies approximately equal to omega(p). Coalescence processes are required to convert the electrostatic waves into transverse radiation which can escape from the source region. Whether the resultant spectrum is nearly a smooth continuum or has a zebra-stripe pattern (both of which occur in type IV bursts) depends on the form of the electron distribution, inhomogeneities in the density and magnetic field, and whether the maser reaches saturation. For at least the case of some type IV dm bursts with fine structure, comparison with observations seems to indicate that the electrons producing the emission are more likely to have a loss-cone distribution, and that the maser instability is not at saturation.

Experimental investigation and DFT calculation of different amine/ammonium salts adsorption on kaolinite

NASA Astrophysics Data System (ADS)

Chen, Jun; Min, Fan-fei; Liu, Lingyun; Liu, Chunfu; Lu, Fangqin

2017-10-01

The adsorption of four different amine/ammonium salts of DDA (Dodecyl amine), MDA (N-methyldodecyl amine), DMDA (N,N-dimethyldodecyl amine) and DTAC (Dodecyl trimethyl ammonium chloride) on kaolinite particles was investigated in the study through the measurement of contact angles, zeta potentials, aggregation observation, adsorption and sedimentation. The results show that different amine/ammonium salts can adsorb on the kaolinite surface to enhance the hydrophobicity and reduce the electronegativity of kaolinite particle surface, and thus induce a strong hydrophobic aggregation of kaolinite particles which promotes the settlement of kaolinite. To explore the adsorption mechanism of these four amine/ammonium salts on kaolinite surfaces, the adsorptions of DDA+, MDA+, DMDA+ and DTAC+ on kaolinite (001) surface and (00 1 bar) surface are calculated with DFT (Density functional theory). The DFT calculation results indicate that different amine/ammonium cations can strongly adsorbed on kaolinite (001) surface and (00 1 bar) surface by forming Nsbnd H⋯O strong hydrogen bonds or Csbnd H⋯O weak hydrogen bonds, and there are strongly electrostatic attractions between different amine/ammonium cations and kaolinite surfaces. The main adsorption mechanism of amine/ammonium cations on kaolinite is hydrogen-bond interaction and electrostatic attraction.

Material forming apparatus using a directed droplet stream

DOEpatents

Holcomb, David E.; Viswanathan, Srinath; Blue, Craig A.; Wilgen, John B.

2000-01-01

Systems and methods are described for rapidly forming precision metallic and intermetallic alloy net shape parts directly from liquid metal droplets. A directed droplet deposition apparatus includes a crucible with an orifice for producing a jet of material, a jet destabilizer, a charging structure, a deflector system, and an impact zone. The systems and methods provide advantages in that fully dense, microstructurally controlled parts can be fabricated at moderate cost.

Frequency multiplexed long range swept source optical coherence tomography

PubMed Central

Zurauskas, Mantas; Bradu, Adrian; Podoleanu, Adrian Gh.

2013-01-01

We present a novel swept source optical coherence tomography configuration, equipped with acousto-optic deflectors that can be used to simultaneously acquire multiple B-scans originating from different depths. The sensitivity range of the configuration is evaluated while acquiring five simultaneous B-scans. Then the configuration is employed to demonstrate long range B-scan imaging by combining two simultaneous B-scans from a mouse head sample. PMID:23760762

Steady flow instability in an annulus with deflectors at rotational vibration

NASA Astrophysics Data System (ADS)

Kozlov, Nikolai V.; Pareau, Dominique; Ivantsov, Andrey; Stambouli, Moncef

2016-12-01

Experimental study and direct numerical simulation of the dynamics of an isothermal low-viscosity fluid are done in a coaxial gap of a cylindrical container making rotational vibrations relative to its axis. On the inner surface of the outer wall of the container, semicircular deflectors are regularly situated, playing the role of flow activators. As a result of vibrations, the activators oscillate tangentially. In the simulation, a 2D configuration is considered, excluding the end-wall effects. In the experiment, a container with a large aspect ratio is used. Steady streaming is generated in the viscous boundary layers on the activators. On each of the latter, beyond the viscous domain, a symmetric vortices pair is formed. The steady streaming in the annulus has an azimuthal periodicity. With an increase in the vibration intensity, a competition between the vortices occurs, as a result of which one of the vortices (let us call it even) approaches the activator and the other one (odd) rolls away and couples with the vortices from the neighbouring pairs. Streamlines of the odd vortices close on each other, forming a cog-wheel shaped flow that encircles the inner wall. Comparison of the experiment and the simulation reveals an agreement at moderate vibration intensity.

A large capacity time division multiplexed (TDM) laser beam combining technique enabled by nanosecond speed KTN deflector

NASA Astrophysics Data System (ADS)

Yin, Stuart (Shizhuo); Chao, Ju-Hung; Zhu, Wenbin; Chen, Chang-Jiang; Campbell, Adrian; Henry, Michael; Dubinskiy, Mark; Hoffman, Robert C.

2017-08-01

In this paper, we present a novel large capacity (a 1000+ channel) time division multiplexing (TDM) laser beam combining technique by harnessing a state-of-the-art nanosecond speed potassium tantalate niobate (KTN) electro-optic (EO) beam deflector as the time division multiplexer. The major advantages of TDM approach are: (1) large multiplexing capability (over 1000 channels), (2) high spatial beam quality (the combined beam has the same spatial profile as the individual beam), (3) high spectral beam quality (the combined beam has the same spectral width as the individual beam, and (4) insensitive to the phase fluctuation of individual laser because of the nature of the incoherent beam combining. The quantitative analyses show that it is possible to achieve over one hundred kW average power, single aperture, single transverse mode solid state and/or fiber laser by pursuing this innovative beam combining method, which represents a major technical advance in the field of high energy lasers. Such kind of 100+ kW average power diffraction limited beam quality lasers can play an important role in a variety of applications such as laser directed energy weapons (DEW) and large-capacity high-speed laser manufacturing, including cutting, welding, and printing.

The Deflector Selector: A Machine Learning Framework for Prioritizing Hazardous Object Deflection Technology Development

NASA Astrophysics Data System (ADS)

Nesvold, Erika; Greenberg, Adam; Erasmus, Nicolas; Van Heerden, Elmarie; Galache, J. L.; Dahlstrom, Eric; Marchis, Franck

2018-01-01

Several technologies have been proposed for deflecting a hazardous Solar System object on a trajectory that would otherwise impact the Earth. The effectiveness of each technology depends on several characteristics of the given object, including its orbit and size. The distribution of these parameters in the likely population of Earth-impacting objects can thus determine which of the technologies are most likely to be useful in preventing a collision with the Earth. None of the proposed deflection technologies has been developed and fully tested in space. Developing every proposed technology is currently prohibitively expensive, so determining now which technologies are most likely to be effective would allow us to prioritize a subset of proposed deflection technologies for funding and development. We will present a new model, the Deflector Selector, that takes as its input the characteristics of a hazardous object or population of such objects and predicts which technology would be able to perform a successful deflection. The model consists of a machine-learning algorithm trained on data produced by N-body integrations simulating the deflections. We will describe the model and present the results of tests of the effectiveness of nuclear explosives, kinetic impactors, and gravity tractors on three simulated populations of hazardous objects.

Ultrafast random-access scanning in two-photon microscopy using acousto-optic deflectors.

PubMed

Salomé, R; Kremer, Y; Dieudonné, S; Léger, J-F; Krichevsky, O; Wyart, C; Chatenay, D; Bourdieu, L

2006-06-30

Two-photon scanning microscopy (TPSM) is a powerful tool for imaging deep inside living tissues with sub-cellular resolution. The temporal resolution of TPSM is however strongly limited by the galvanometric mirrors used to steer the laser beam. Fast physiological events can therefore only be followed by scanning repeatedly a single line within the field of view. Because acousto-optic deflectors (AODs) are non-mechanical devices, they allow access at any point within the field of view on a microsecond time scale and are therefore excellent candidates to improve the temporal resolution of TPSM. However, the use of AOD-based scanners with femtosecond pulses raises several technical difficulties. In this paper, we describe an all-digital TPSM setup based on two crossed AODs. It includes in particular an acousto-optic modulator (AOM) placed at 45 degrees with respect to the AODs to pre-compensate for the large spatial distortions of femtosecond pulses occurring in the AODs, in order to optimize the spatial resolution and the fluorescence excitation. Our setup allows recording from freely selectable point-of-interest at high speed (1kHz). By maximizing the time spent on points of interest, random-access TPSM (RA-TPSM) constitutes a promising method for multiunit recordings with millisecond resolution in biological tissues.

KSC-05PD-0893

NASA Technical Reports Server (NTRS)

2005-01-01

KENNEDY SPACE CENTER, FLA. During a walkdown of Launch Pad 39B, the STS-114 crew pauses for a photograph in the flame trench underneath the pad. The flame trench, built with concrete and refractory brick, bisects the pad at ground level. It is 490 feet long, 58 feet wide and 42 feet deep. The flame deflector system includes an inverted, V-shaped steel structure covered with a high-temperature concrete material five inches thick that extends across the center of the flame trench. One side of the V receives and deflects the flames from the Orbiter main engines; the opposite side deflects the flames from the Solid Rocket Boosters. There are also two movable deflectors at the top of the trench to provide additional protection to Shuttle hardware from the Solid Rocket Booster flames. STS-114 is designated the first Return to Flight mission, with a launch window extending from July 13 to July 31. The crew is at KSC for Terminal Countdown Demonstration Test (TCDT) activities. The TCDT is held at KSC prior to each Space Shuttle flight. It provides the crew of each mission an opportunity to participate in simulated countdown activities. The test ends with a mock launch countdown culminating in a simulated main engine cutoff. The crew also spends time undergoing emergency egress training exercises at the launch pad.

The Deflector Selector: A machine learning framework for prioritizing hazardous object deflection technology development

NASA Astrophysics Data System (ADS)

Nesvold, E. R.; Greenberg, A.; Erasmus, N.; van Heerden, E.; Galache, J. L.; Dahlstrom, E.; Marchis, F.

2018-05-01

Several technologies have been proposed for deflecting a hazardous Solar System object on a trajectory that would otherwise impact the Earth. The effectiveness of each technology depends on several characteristics of the given object, including its orbit and size. The distribution of these parameters in the likely population of Earth-impacting objects can thus determine which of the technologies are most likely to be useful in preventing a collision with the Earth. None of the proposed deflection technologies has been developed and fully tested in space. Developing every proposed technology is currently prohibitively expensive, so determining now which technologies are most likely to be effective would allow us to prioritize a subset of proposed deflection technologies for funding and development. We present a new model, the Deflector Selector, that takes as its input the characteristics of a hazardous object or population of such objects and predicts which technology would be able to perform a successful deflection. The model consists of a machine-learning algorithm trained on data produced by N-body integrations simulating the deflections. We describe the model and present the results of tests of the effectiveness of nuclear explosives, kinetic impactors, and gravity tractors on three simulated populations of hazardous objects.

Predicted Static Aeroelastic Effects on Wings with Supersonic Leading Edges and Streamwise Tips

NASA Technical Reports Server (NTRS)

Brown, Stuart C.

1959-01-01

A method is presented for calculation of static aeroelastic effects on wings with supersonic leading edges and streamwise tips. Both chord-wise and spanwise deflections are taken into account. Aerodynamic and structural forces are introduced in influence coefficient form; the former are developed from linearized supersonic wing theory and the latter are assumed to be known from load-deflection tests or theory. The predicted effects of flexibility on lateral-control effectiveness, damping in roll, and lift-curve slope are shown for a low-aspect-ratio wing at Mach numbers of 1.25 and 2.60. The control effectiveness is shown for a trailing-edge aileron, a tip aileron, and a slot-deflector spoiler located along the 0.70 chord line. The calculations indicate that the tip aileron is particularly attractive from an aeroelastic standpoint, because the changes in effectiveness with dynamic pressure are small compared to the changes in effectiveness of the trailing-edge aileron and slot-deflector spoiler. The effects of making several simplifying assumptions in the example calculations are shown. The use of a modified strip theory to determine the aerodynamic influence coefficients gave adequate results only for the high Mach number case. Elimination of chordwise bending in the structural influence coefficients exaggerated the aeroelastic effects on rolling-moment and lift coefficients for both Mach numbers.

Experimental energy resolution of a paracentric hemispherical deflector analyzer for different entry positions and bias

NASA Astrophysics Data System (ADS)

Dogan, M.; Ulu, M.; Gennarakis, G. G.; Zouros, T. J. M.

2013-04-01

A specially designed hemispherical deflector analyzer (HDA) with 5-element input lens having a movable entry position R0 suitable for electron energy analysis in atomic collisions was constructed and tested. The energy resolution of the HDA was experimentally determined for three different entry positions R0 = 84, 100, 112 mm as a function of the nominal entry potential V(R0) under pre-retardation conditions. The resolution for the (conventional) entry at the mean radius R0 = 100 mm was found to be a factor of 1.6-2 times worse than the resolution for the two (paracentric) positions R0 = 84 and 112 mm at particular values of V(R0). These results provide the first experimental verification and a proof of principle of the utility of such a paracentric HDA, while demonstrating its advantages over the conventional HDA: greater dispersion with reduced angular aberrations resulting in better energy resolution without the use of any additional fringing field correction electrodes. Supporting simulations of the entire lens plus HDA spectrometer are also provided and mostly found to be within 20%-30% of experimental values. The paracentric HDA is expected to provide a lower cost and/or more compact alternative to the conventional HDA particularly useful in modern applications utilizing a position sensitive detector.

Experimental energy resolution of a paracentric hemispherical deflector analyzer for different entry positions and bias.

PubMed

Dogan, M; Ulu, M; Gennarakis, G G; Zouros, T J M

2013-04-01

A specially designed hemispherical deflector analyzer (HDA) with 5-element input lens having a movable entry position R0 suitable for electron energy analysis in atomic collisions was constructed and tested. The energy resolution of the HDA was experimentally determined for three different entry positions R0 = 84, 100, 112 mm as a function of the nominal entry potential V(R0) under pre-retardation conditions. The resolution for the (conventional) entry at the mean radius R0 = 100 mm was found to be a factor of 1.6-2 times worse than the resolution for the two (paracentric) positions R0 = 84 and 112 mm at particular values of V(R0). These results provide the first experimental verification and a proof of principle of the utility of such a paracentric HDA, while demonstrating its advantages over the conventional HDA: greater dispersion with reduced angular aberrations resulting in better energy resolution without the use of any additional fringing field correction electrodes. Supporting simulations of the entire lens plus HDA spectrometer are also provided and mostly found to be within 20%-30% of experimental values. The paracentric HDA is expected to provide a lower cost and∕or more compact alternative to the conventional HDA particularly useful in modern applications utilizing a position sensitive detector.

Launch Pad Flame Trench Refractory Materials

NASA Technical Reports Server (NTRS)

Calle, Luz M.; Hintze, Paul E.; Parlier, Christopher R.; Bucherl, Cori; Sampson, Jeffrey W.; Curran, Jerome P.; Kolody, Mark; Perusich, Steve; Whitten, Mary

2010-01-01

The launch complexes at NASA's John F. Kennedy Space Center (KSC) are critical support facilities for the successful launch of space-based vehicles. These facilities include a flame trench that bisects the pad at ground level. This trench includes a flame deflector system that consists of an inverted, V-shaped steel structure covered with a high temperature concrete material five inches thick that extends across the center of the flame trench. One side of the "V11 receives and deflects the flames from the orbiter main engines; the opposite side deflects the flames from the solid rocket boosters. There are also two movable deflectors at the top of the trench to provide additional protection to shuttle hardware from the solid rocket booster flames. These facilities are over 40 years old and are experiencing constant deterioration from launch heat/blast effects and environmental exposure. The refractory material currently used in launch pad flame deflectors has become susceptible to failure, resulting in large sections of the material breaking away from the steel base structure and creating high-speed projectiles during launch. These projectiles jeopardize the safety of the launch complex, crew, and vehicle. Post launch inspections have revealed that the number and frequency of repairs, as well as the area and size of the damage, is increasing with the number of launches. The Space Shuttle Program has accepted the extensive ground processing costs for post launch repair of damaged areas and investigations of future launch related failures for the remainder of the program. There currently are no long term solutions available for Constellation Program ground operations to address the poor performance and subsequent failures of the refractory materials. Over the last three years, significant liberation of refractory material in the flame trench and fire bricks along the adjacent trench walls following Space Shuttle launches have resulted in extensive investigations of failure mechanisms, load response, ejected material impact evaluation, and repair design analysis (environmental and structural assessment, induced environment from solid rocket booster plume, loads summary, and repair integrity), assessment of risk posture for flame trench debris, and justification of flight readiness rationale. Although the configuration of the launch pad, water and exhaust direction, and location of the Mobile Launcher Platform between the flame trench and the flight hardware should protect the Space Vehicle from debris exposure, loss of material could cause damage to a major element of the ground facility (resulting in temporary usage loss); and damage to other facility elements is possible. These are all significant risks that will impact ground operations for Constellation and development of new refractory material systems is necessary to reduce the likelihood of the foreign object debris hazard during launch. KSC is developing an alternate refractory material for the launch pad flame trench protection system, including flame deflector and flame trench walls, that will withstand launch conditions without the need for repair after every launch, as is currently the case. This paper will present a summary of the results from industry surveys, trade studies, life cycle cost analysis, and preliminary testing that have been performed to support and validate the development, testing, and qualification of new refractory materials.

Bibliography of Soviet Laser Developments, Number 27, January - February 1977.

DTIC Science & Technology

1977-11-21

is 3. Deflectors .......................................... 15 4. Filters .............................................. 16 5. Mirrors ...Leont’yev and A.M. Khapayev (2). Study of the effect of a mirror aperture on the pro- perties of a hemispherical Fabry-Perot resonator. VMU, no. 4, 1976...modes in a resonator with an aperture in the mirror . ZhPS, v. 26, no. 1, 1977, 141-143. 2. Pump Sources 108. Kruglov, B.V., V.P. Osetrov, G.V

Low-energy beam transport studies supporting the spallation neutron source 1-MW beam operation.

PubMed

Han, B X; Kalvas, T; Tarvainen, O; Welton, R F; Murray, S N; Pennisi, T R; Santana, M; Stockli, M P

2012-02-01

The H(-) injector consisting of a cesium enhanced RF-driven ion source and a 2-lens electrostatic low-energy beam transport (LEBT) system supports the spallation neutron source 1 MW beam operation with ∼38 mA beam current in the linac at 60 Hz with a pulse length of up to ∼1.0 ms. In this work, two important issues associated with the low-energy beam transport are discussed: (1) inconsistent dependence of the post-radio frequency quadrupole accelerator beam current on the ion source tilt angle and (2) high power beam losses on the LEBT electrodes under some off-nominal conditions compromising their reliability.

Interaction of upgoing auroral H(+) and O(+) beams

NASA Technical Reports Server (NTRS)

Kaufmann, R. L.; Ludlow, G. R.; Collin, H. L.; Peterson, W. K.; Burch, J. L.

1986-01-01

Data from the S3-3 and DE 1 satellites are analyzed to study the interaction between H(+) and O(+) ions in upgoing auroral beams. Every data set analyzed showed some evidence of an interaction. The measured plasma was found to be unstable to a low-frequency electrostatic wave that propagates at an oblique angle to vector-B(0). A second wave, which can propagate parallel to vector-B(0), is weakly damped in the plasma studied in most detail. It is likely that the upgoing ion beams generate this parallel wave at lower altitudes. The resulting wave-particle interactions qualitatively can explain most of the features observed in ion distribution functions.

Monitoring the layer-by-layer self-assembly of graphene and graphene oxide by spectroscopic ellipsometry.

PubMed

Zhou, Kai-Ge; Chang, Meng-Jie; Wang, Hang-Xing; Xie, Yu-Long; Zhang, Hao-Li

2012-01-01

Thin films of graphene oxide, graphene and copper (II) phthalocyanine dye have been successfully fabricated by electrostatic layer-by-layer (LbL) assembly approach. We present the first variable angle spectroscopic ellipsometry (VASE) investigation on these graphene-dye hybrid thin films. The thickness evaluation suggested that our LbL assembly process produces highly uniform and reproducible thin films. We demonstrate that the refractive indices of the graphene-dye thin films undergo dramatic variation in the range close to the absorption of the dyes. This investigation provides new insight to the optical properties of graphene containing thin films and shall help to establish an appropriate optical model for graphene-based hybrid materials.

Ultralow-voltage design of graphene PN junction quantum reflective switch transistor

NASA Astrophysics Data System (ADS)

Sohier, Thibault; Yu, Bin

2011-05-01

We propose the concept of a graphene-based quantum reflective switch (QRS) for low-power logic application. With the unique electronic properties of graphene, a tilted PN junction is used to implement logic switch function with 103 ON/OFF ratio. Carriers are reflected on an electrostatically induced potential step with strong incidence-angle-dependency due to the widening of classically forbidden energies. Optimized design of the device for ultralow-voltage operating has been conducted. The device is constantly ON with a turning-off gate voltage around 180 mV using thin HfO2 as the gate dielectric. The results suggest a class of logic switch devices operating with micropower dissipation.

Surface-micromachined 2D optical scanners with optically flat single-crystalline silicon micromirrors

NASA Astrophysics Data System (ADS)

Su, John G.; Patterson, Pamela R.; Wu, Ming C.

2001-05-01

We have developed a novel wafer-scale single-crystalline silicon micromirror bonding process to fabricate optically flat micromirrors on polysilicon surface-micromachined 2D scanners. The electrostatically actuated 2D scanner has a mirror area of 450 micrometers x 450 micrometers and an optical scan angle of +/- +/-7.5 degree(s). Compared to micromirrors made with a standard polysilicon surface-micromachining process, the radius of curvature of the micromirror has been improved by 1 50 times from 1.8 cm to 265 cm, with surface roughness < 10 nm. Besides, single-crystalline honeycomb micromirrors derived from silicon on insulator (SOI) have been developed to reduce the mass of the bonded mirror.

THOR Ion Mass Spectrometer (IMS)

NASA Astrophysics Data System (ADS)

Retinò, Alessandro

2017-04-01

Turbulence Heating ObserveR (THOR) is the first mission ever flown in space dedicated to plasma turbulence. The Ion Mass Spectrometer (IMS) onboard THOR will provide the first high-time resolution measurements of mass-resolved ions in near-Earth space, focusing on hot ions in the foreshock, shock and magnetosheath turbulent regions. These measurements are required to study how kinetic-scale turbulent fluctuations heat and accelerate different ion species. IMS will measure the full three-dimensional distribution functions of main ion species (H+, He++, O+) in the energy range 10 eV/q to 30 keV/q with energy resolution DE/E down to 10% and angular resolution down to 11.25˚ . The time resolution will be 150 ms for O+, 300 ms for He++ and ˜ 1s for O+, which correspond to ion scales in the the foreshock, shock and magnetosheath regions. Such high time resolution is achieved by mounting four identical IMS units phased by 90˚ in the spacecraft spin plane. Each IMS unit combines a top-hat electrostatic analyzer with deflectors at the entrance together with a time-of-flight section to perform mass selection. Adequate mass-per-charge resolution (M/q)/(ΔM/q) (≥ 8 for He++ and ≥ 3 for O+) is obtained through a 6 cm long Time-of-Flight (TOF) section. IMS electronics includes a fast sweeping high voltage board that is required to make measurements at high cadence. Ion detection includes Micro Channel Plates (MCPs) combined with Application-Specific Integrated Circuits (ASICs) for charge amplification and discrimination and a discrete Time-to-Amplitude Converter (TAC) to determine the ion time of flight. A processor board will be used to for ion events formatting and will interface with the Particle Processing Unit (PPU), which will perform data processing for THOR particle detectors. The IMS instrument is being designed and will be built and calibrated by an international consortium of scientific institutes from France, USA, Germany and Japan and Switzerland.

Electrostatic persistence length.

PubMed

Fixman, Marshall

2010-03-11

The persistence length is calculated for polyelectrolyte chains with fixed bond lengths and bond angles (pi-theta), and a potential energy consisting of the screened Coulomb interaction between beads, potential wells alpha phi(i)2 for the dihedral angles phi(i), and coupling terms beta phi(i) phi(i+/-1). This model defines a librating chain that reduces in appropriate limits to the freely rotating or wormlike chains, it can accommodate local crumpling or extreme stiffness, and it is easy to simulate. A planar-quadratic (pq), analytic approximation is based on an expansion of the electrostatic energy in eigenfunctions of the quadratic form that describes the backbone energy, and on the assumption that the quadratic form not only is positive but also adequately confines the chain in an infinite phase space of dihedral angles to the physically unique part with all |phi(i)| < pi. The pq approximation is available under these weak constraints, but the simulations confirm its quantitative accuracy only under the expected condition that alpha is large, that is, for very stiff chains. Stiff chains can also be simulated with small alpha and small theta and compared to an OSF approximation suitably generalized to chains with finite rather than vanishing theta, and increasing agreement with OSF is found the smaller is theta. The two approximations, one becoming exact as alpha --> infinity with fixed theta, the other as theta --> 0 with fixed alpha, are quantitatively similar in behavior, both giving a persistence length P = P0 + aD2 for stiff chains, where D is the Debye length. However, the coefficient apq is about twice the value of aOSF. Under other conditions the simulations show that P may or not be linear in D2 at small or moderate D, depending on the magnitudes of alpha, beta, theta, and the charge density but always becomes linear at large D. Even at a moderately low charge density, corresponding to fewer than 20% of the beads being charged, and with strong crumpling induced by large beta, increasing D dissolves blobs and recovers a linear dependence of P on D2, although a lower power of D gives an adequate fit at moderate D. For the class of models considered, it is concluded that the only universal feature is the asymptotic linearity of P in D2, regardless of flexibility or stiffness.

Optical pattern recognition architecture implementing the mean-square error correlation algorithm

DOEpatents

Molley, Perry A.

1991-01-01

An optical architecture implementing the mean-square error correlation algorithm, MSE=.SIGMA.[I-R].sup.2 for discriminating the presence of a reference image R in an input image scene I by computing the mean-square-error between a time-varying reference image signal s.sub.1 (t) and a time-varying input image signal s.sub.2 (t) includes a laser diode light source which is temporally modulated by a double-sideband suppressed-carrier source modulation signal I.sub.1 (t) having the form I.sub.1 (t)=A.sub.1 [1+.sqroot.2m.sub.1 s.sub.1 (t)cos (2.pi.f.sub.o t)] and the modulated light output from the laser diode source is diffracted by an acousto-optic deflector. The resultant intensity of the +1 diffracted order from the acousto-optic device is given by: I.sub.2 (t)=A.sub.2 [+2m.sub.2.sup.2 s.sub.2.sup.2 (t)-2.sqroot.2m.sub.2 (t) cos (2.pi.f.sub.o t] The time integration of the two signals I.sub.1 (t) and I.sub.2 (t) on the CCD deflector plane produces the result R(.tau.) of the mean-square error having the form: R(.tau.)=A.sub.1 A.sub.2 {[T]+[2m.sub.2.sup.2.multidot..intg.s.sub.2.sup.2 (t-.tau.)dt]-[2m.sub.1 m.sub.2 cos (2.tau.f.sub.o .tau.).multidot..intg.s.sub.1 (t)s.sub.2 (t-.tau.)dt]} where: s.sub.1 (t) is the signal input to the diode modulation source: s.sub.2 (t) is the signal input to the AOD modulation source; A.sub.1 is the light intensity; A.sub.2 is the diffraction efficiency; m.sub.1 and m.sub.2 are constants that determine the signal-to-bias ratio; f.sub.o is the frequency offset between the oscillator at f.sub.c and the modulation at f.sub.c +f.sub.o ; and a.sub.o and a.sub.1 are constant chosen to bias the diode source and the acousto-optic deflector into their respective linear operating regions so that the diode source exhibits a linear intensity characteristic and the AOD exhibits a linear amplitude characteristic.

Calibration of the MDCO dust collector and of four versions of the inverted frisbee dust deposition sampler

NASA Astrophysics Data System (ADS)

Sow, Mamadou; Goossens, Dirk; Rajot, Jean Louis

2006-12-01

Wind tunnel experiments were conducted to determine the efficiency of sediment samplers designed to measure the deposition of aeolian dust. Efficiency was ascertained relative to a water surface, which was considered the best alternative for simulating a perfectly absorbent surface. Two types of samplers were studied: the Marble Dust Collector (MDCO) and the inverted frisbee sampler. Four versions of the latter catcher were tested: an empty frisbee, an empty frisbee surrounded by an aerodynamic flow deflector ring, a frisbee filled with glass marbles, and a frisbee filled with glass marbles and surrounded by a flow deflector ring. Efficiency was ascertained for five wind velocities (range: 1-5 m s - 1 ) and eight grain size classes (range: 10-89 μm). The efficiency of dust deposition catchers diminishes rapidly as the wind speed increases. It also diminishes as the particles caught become coarser. Adding a flow deflector ring to a catcher substantially improves the catcher's efficiency, by up to 100% in some cases. The addition of glass marbles to a catcher, on the other hand, does not seem to increase the efficiency, at least not at wind velocities inferior to the deflation threshold. For higher velocities the marbles protect the settled particles from resuspension, keeping them in the catcher. The following five parameters determine the accumulation of aeolian dust in a catcher: the horizontal dust flux, the weight of the particles, atmospheric turbulence, resuspension, and the dust shadow effect created by the catcher. The final accumulation flux depends on the combination of these parameters. The catchers tested in this study belong to the best catchers currently in use in earth science and have been the subject of various aerodynamic studies to improve their efficiency. Nevertheless the catching efficiency remains low, in the order of 20-40% for wind speeds above 2 m s - 1 . Other catchers suffer from the same low efficiencies. There is, thus, evidence to believe that dust deposition rates published in the aeolian literature and obtained by collecting the sediment in a catcher largely underestimate the true deposition. The errors are considerable, of the order of 100% and more. A reconsideration of the literature data on aeolian dust deposition measured by catchers is, therefore, required.

Soil-release behaviour of polyester fabrics after chemical modification with polyethylene glycol

NASA Astrophysics Data System (ADS)

Miranda, T. M. R.; Santos, J.; Soares, G. M. B.

2017-10-01

The fibres cleanability depends, among other characteristics, on their hydrophilicity. Hydrophilic fibres are easy-wash materials but hydrophobic fibres are difficult to clean due to their higher water-repellent surfaces. This type of surfaces, like polyester (PET), produce an accumulation of electrostatic charges, which favors adsorption and retention of dirt. Thus, the polyester soil-release properties can be increased by finishing processes that improve fiber hydrophilicity. In present study, PET fabric modification was described by using poly(ethylene glycol) (PEG) and N,N´-dimethylol-4,5-dihydroxyethylene urea (DMDHEU) chemically modified resin. Briefly, the modification process was carried out in two steps, one to hydrolyse the polyester and create hydroxyl and carboxylic acid groups on the surface and other to crosslink the PEG chains. The resulting materials were characterized by contact angle, DSC and FTIR-ATR methods. Additionally, the soil release behavior and the mechanical properties of modified PET were evaluated. For the best process conditions, the treated PET presented 0° contact angle, grade 5 stain release and acceptable mechanical performance.

Space charge influence on the angle of conical spikes developing on a liquid-metal anode.

PubMed

Boltachev, G Sh; Zubarev, N M; Zubareva, O V

2008-05-01

The influence of the space charge of ions emitted from the surface of a conical spike on its shape has been studied. The problem of the calculation of the spatial distributions of the electric field, ion velocity field, and the space charge density near the cone tip has been reduced to the analysis of a system of ordinary differential equations. As a result of numerical solution of these equations, the criterion for the balance of the capillary and electrostatic forces on the conic surface of a liquid-metal anode has been determined. It has allowed us to relate the electrical current flowing through the system, the applied potential difference, and the cone angle. We have compared the results of our calculations with available experimental data concerning emission from the surface of pure liquid gallium, indium, tin, and some liquid alloys, such as Au+Si , Co+Ge , and Au+Ge . On the basis of the proposed model, explanations have been given for a number of specific features of the emissive behavior of different systems.

Modeling and Simulation of a Parametrically Resonant Micromirror With Duty-Cycled Excitation.

PubMed

Shahid, Wajiha; Qiu, Zhen; Duan, Xiyu; Li, Haijun; Wang, Thomas D; Oldham, Kenn R

2014-12-01

High frequency large scanning angle electrostatically actuated microelectromechanical systems (MEMS) mirrors are used in a variety of applications involving fast optical scanning. A 1-D parametrically resonant torsional micromirror for use in biomedical imaging is analyzed here with respect to operation by duty-cycled square waves. Duty-cycled square wave excitation can have significant advantages for practical mirror regulation and/or control. The mirror's nonlinear dynamics under such excitation is analyzed in a Hill's equation form. This form is used to predict stability regions (the voltage-frequency relationship) of parametric resonance behavior over large scanning angles using iterative approximations for nonlinear capacitance behavior of the mirror. Numerical simulations are also performed to obtain the mirror's frequency response over several voltages for various duty cycles. Frequency sweeps, stability results, and duty cycle trends from both analytical and simulation methods are compared with experimental results. Both analytical models and simulations show good agreement with experimental results over the range of duty cycled excitations tested. This paper discusses the implications of changing amplitude and phase with duty cycle for robust open-loop operation and future closed-loop operating strategies.

Mm-size bistable zipping dielectric elastomer actuators for integrated microfluidics

NASA Astrophysics Data System (ADS)

Maffli, Luc; Rosset, Samuel; Shea, Herbert R.

2013-04-01

We report on a new structure of Dielectric Elastomer Actuators (DEAs) called zipping DEAs, which have a set of unique characteristics that are a good match for the requirements of electrically-powered integrated microfluidic pumping and/or valving units as well as Braille displays. The zipping DEAs operate by pulling electrostatically an elastomer membrane in contact with the rigid sidewalls of a sloped chamber. In this work, we report on fully functional mm-size zipping DEAs that demonstrate a complete sealing of the chamber sidewalls and a tunable bistable behavior, and compare the measurements with an analytical model. Compared to our first generation of devices, we are able vary the sidewall angle and benefit therefore from more flexibility to study the requirements to make fully functional actuators. In particular, we show that with Nusil CF19 as membrane material (1.2 MPa Young's modulus), it is possible to zip completely 2.3 mm diameter chambers with 15° and 21° sidewalls angle equibiaxially prestretched to λ0=1.12 and 15° chambers with λ0=1.27.

Ion Plume Damage in Formation Flight Regimes

NASA Astrophysics Data System (ADS)

Young, Jarred Alexander

This effort examines the potential for damage from plume impingement from an electric propulsion system within spacecraft missions that utilize a formation flight architecture. Specifically, the potential erosion of a structural material (Aluminum) and anti-reflective coatings for solar cell coverglass are explored. Sputter yields for the materials of Aluminum, Magnesium Fluoride, and Indium Tin Oxide are experimentally validated using an electrostatic ion source at energies varying from 500-1500 eV. Erosion depths are analyzed using white-light optical profilometry to measure potential depths up to 1 microm. This erosion data was then utilized to create (or augment) Bohdansky and Yamamura theoretical curve fits for multiple incidence angles to look at theoretical sputter effects within formation flight regimes at multiple formation distances from 50-1000 m. The damage from these electric propulsion plumes is explored throughout multiple orbital conditions from LEO, Sun-Synchronous, and GEO. Factors affecting erosion are: plume density, local geomagnetic field environment and incidence angles of target surfaces. Results from this simulated study show significant erosion with GEO with minor erosion in some LEO and all Sun-Synchronous cases.

Flow Quality for Turbine Engine Loads Simulator (TELS) Facility

DTIC Science & Technology

1980-06-01

2.2 GAS INGESTION A mathematical simulation of the turbojet engine and jet deflector was formulated to estimate the severity of the recirculating...3. Swain. R. L. and Mitchell, J. G. "’Smlulatlon of Turbine Engine Operational Loads." Journal of Aircraft Vol. 15, No. 6, June 1978• 4. Ryan, J...3 AEDC-TR-79-83 ~...~ i ,i g - Flow Quality for Turbine Engine Loads Simulator (TELS) Facility R..I. Schulz ARO, Inc. June 1980

JPRS Report, Science and Technology: China.

DTIC Science & Technology

1989-03-17

Optical Absorption Property of TiO -Doped Vycor Glass [Ling Ping, et al.; WULI XUEBAO, No 11, Nov 88] ......... 81 Generation of Short Pulse of 30 fs...et al.; YINGYONG JIGUANG, No 6, Dec 88] 94 High-Resolution TeO2 Acousto-Optic Deflector for mm-Wave Radio Spectrometer [Xu Binghuo, et al.; YINGYONG...Nov 88] ......... 159 Study of Structural Relaxation of Metallic Glass (Feo. 8 5Nio.15)84 B1 6 by Measuring Thermal Expansion, Resistance Under Zero

Saturn Apollo Program

NASA Image and Video Library

1965-04-16

This photograph depicts a dramatic view of the first test firing of all five F-1 engines for the Saturn V S-IC stage at the Marshall Space Flight Center. The testing lasted a full duration of 6.5 seconds. It also marked the first test performed in the new S-IC static test stand and the first test using the new control blockhouse. The S-IC stage is the first stage, or booster, of a 364-foot long rocket that ultimately took astronauts to the Moon. Operating at maximum power, all five of the engines produced 7,500,000 pounds of thrust. Required to hold down the brute force of a 7,500,000-pound thrust, the S-IC static test stand was designed and constructed with the strength of hundreds of tons of steel and cement, planted down to bedrock 40 feet below ground level. The structure was topped by a crane with a 135-foot boom. With the boom in the up position, the stand was given an overall height of 405 feet, placing it among the highest structures in Alabama at the time. When the Saturn V S-IC first stage was placed upright in the stand , the five F-1 engine nozzles pointed downward on a 1,900 ton, water-cooled deflector. To prevent melting damage, water was sprayed through small holes in the deflector at the rate 320,000 gallons per minute.

DES meets Gaia: discovery of strongly lensed quasars from a multiplet search

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

Agnello, A.; et al.

We report the discovery, spectroscopic confirmation and first lens models of the first two, strongly lensed quasars from a combined search in WISE and Gaia over the DES footprint. The four-image lensWGD2038-4008 (r.a.=20:38:02.65, dec.=-40:08:14.64) has source- and lens-redshiftsmore » $$z_{s}=0.777 \\pm 0.001$$ and $$z_l = 0.230 \\pm 0.002$$ respectively. Its deflector has effective radius $$R_{\\rm eff} \\approx 3.4^{\\prime\\prime}$$, stellar mass $$\\log(M_{\\star}/M_{\\odot}) = 11.64^{+0.20}_{-0.43}$$, and shows extended isophotal shape variation. Simple lens models yield Einstein radii $$R_{\\rm E}=(1.30\\pm0.04)^{\\prime\\prime},$$ axis ratio $$q=0.75\\pm0.1$$ (compatible with that of the starlight) and considerable shear-ellipticity degeneracies. The two-image lensWGD2021-4115 (r.a.=20:21:39.45, dec.=--41:15:57.11) has $$z_{s}=1.390\\pm0.001$$ and $$z_l = 0.335 \\pm 0.002$$, and Einstein radius $$R_{\\rm E} = (1.1\\pm0.1)^{\\prime\\prime},$$ but higher-resolution imaging is needed to accurately separate the deflector and faint quasar image. We also show high-rank candidate doubles selected this way, some of which have been independently identified with different techniques, and discuss a DES+WISE quasar multiplet selection.« less

Exploring the origin of the internal rotational barrier for molecules with one rotatable dihedral angle

PubMed Central

Liu, Shubin; Govind, Niranjan; Pedersen, Lee G.

2008-01-01

Continuing our recent endeavor, we systematically investigate in this work the origin of internal rotational barriers for small molecules using the new energy partition scheme proposed recently by one of the authors [S. B. Liu, J. Chem. Phys. 126, 244103 (2007)], where the total electronic energy is decomposed into three independent components, steric, electrostatic, and fermionic quantum. Specifically, we focus in this work on six carbon, nitrogen, and oxygen containing hydrides, CH3CH3, CH3NH2, CH3OH, NH2NH2, NH2OH, and H2O2, with only one rotatable dihedral angle ∠H–X–Y–H (X,Y=C,N,O). The relative contributions of the different energy components to the total energy difference as a function of the internal dihedral rotation will be considered. Both optimized-geometry (adiabatic) and fixed-geometry (vertical) differences are examined, as are the results from the conventional energy partition and natural bond orbital analysis. A wealth of strong linear relationships among the total energy difference and energy component differences for different systems have been observed but no universal relationship applicable to all systems for both cases has been discovered, indicating that even for simple systems such as these, there exists no omnipresent, unique interpretation on the nature and origin of the internal rotation barrier. Different energy components can be employed for different systems in the rationalization of the barrier height. Confirming that the two differences, adiabatic and vertical, are disparate in nature, we find that for the vertical case there is a unique linear relationship applicable to all the six molecules between the total energy difference and the sum of the kinetic and electrostatic energy differences. For the adiabatic case, it is the total potential energy difference that has been found to correlate well with the total energy difference except for ethane whose rotation barrier is dominated by the quantum effect. PMID:19044862

CESR Upgrade: Plans and Recent Performance

NASA Astrophysics Data System (ADS)

Rogers, Joseph T.

1996-05-01

We are now in the second phase of a program to substantially upgrade the luminosity of the CESR e^+ e^- collider by increasing the number of stored bunches. In the first phase, completed in 1995, we progressed from collisions of beams of 7 bunches to beams of 9 trains of two bunches each, achieving a record luminosity of 3.2 × 10^32 cm-2s-1. To avoid unwanted collisions at each side of the interaction point, we electrostatically separate the beams on antisymmetric orbits, with a ± 2.1 mrad crossing angle at the interaction point. For the second phase we have altered the interaction region quadrupole magnets to increase the physical aperture and to reduce the maximum horizontal β in this region. We plan to store 9 trains of 3 bunches in the second phase, and anticipate a luminosity of 6 × 10^32 cm-2s-1. In the third phase installation, to begin in late 1997, we will replace the interaction region quadrupoles with a combination of a permanent magnet quadrupole and superconducting quadrupole pair on each side of the interaction point, which will further reduce the β functions throughout the interaction region and at the interaction point. To accomodate the higher currents we will replace each of the four 5-cell copper RF cavities with a single-cell superconducting cavity. In this phase we expect to achieve a luminosity in excess of 10^33 cm-2s-1 with 9 trains of 5 bunches. Recent development work includes the successful test of a superconducting RF cavity in CESR, installation of low-impedance electrostatic separators, upgrades to the vacuum system, a fast digital transverse feedback system, and new beam diagnostics. Recent studies have revealed the effects of collision at a crossing angle, the behavior of the long range beam-beam interaction at parasitic crossings, and the relationship of the dominant multibunch instability to photoemission in the beam chamber.

PCE: web tools to compute protein continuum electrostatics

PubMed Central

Miteva, Maria A.; Tufféry, Pierre; Villoutreix, Bruno O.

2005-01-01

PCE (protein continuum electrostatics) is an online service for protein electrostatic computations presently based on the MEAD (macroscopic electrostatics with atomic detail) package initially developed by D. Bashford [(2004) Front Biosci., 9, 1082–1099]. This computer method uses a macroscopic electrostatic model for the calculation of protein electrostatic properties, such as pKa values of titratable groups and electrostatic potentials. The MEAD package generates electrostatic energies via finite difference solution to the Poisson–Boltzmann equation. Users submit a PDB file and PCE returns potentials and pKa values as well as color (static or animated) figures displaying electrostatic potentials mapped on the molecular surface. This service is intended to facilitate electrostatics analyses of proteins and thereby broaden the accessibility to continuum electrostatics to the biological community. PCE can be accessed at . PMID:15980492

Self-similar assemblies of globular whey proteins at the air-water interface: effect of the structure.

PubMed

Mahmoudi, Najet; Gaillard, Cédric; Boué, François; Axelos, Monique A V; Riaublanc, Alain

2010-05-01

We investigated the structure of heat-induced assemblies of whey globular proteins using small angle neutron scattering (SANS), static and dynamic light scattering (SLS and DLS), and cryogenic transmission electron microscopy (Cryo-TEM). Whey protein molecules self-assemble in fractal aggregates with a structure density depending on the electrostatic interactions. We determined the static and dynamic properties of interfacial layer formed by the protein assemblies, upon adsorption and spreading at the air-water interface using surface film balance and interfacial dilatational rheology. Upon spreading, all whey protein systems show a power-law scaling behavior of the surface pressure versus concentration in the semi-dilute surface concentration regime, with an exponent ranging from 5.5 to 9 depending on the electrostatic interactions and the aggregation state. The dilatational modulus derived from surface pressure isotherms shows a main peak at 6-8 mN/m, generally considered to be the onset of a conformational change in the monolayer, and a second peak or a shoulder at 15 mN/m. Long-time adsorption kinetics give similar results for both the native whey proteins and the corresponding self-similar assemblies, with a systematic effect of the ionic strength. Copyright 2010 Elsevier Inc. All rights reserved.

Electrostatic-probe measurements of plasma parameters for two reentry flight experiments at 25000 feet per second

NASA Technical Reports Server (NTRS)

Jones, W. L., Jr.; Cross, A. E.

1972-01-01

Unique plasma diagnostic measurements at high altitudes from two geometrically similar blunt body reentry spacecraft using electrostatic probe rakes are presented. The probes measured the positive ion density profiles (shape and magnitude) during the two flights. The probe measurements were made at eight discrete points (1 cm to 7 cm) from the vehicle surface in the aft flow field of the spacecraft over the altitude range of 85.3 to 53.3 km (280,000 to 175,000 ft) with measured densities of 10 to the 8th power to 10 to the 12th power electrons/cu cm, respectively. Maximum reentry velocity for each spacecraft was approximately 7620 meters/second (25,000 ft/sec). In the first flight experiment, water was periodically injected into a flow field which was contaminated by ablation products from the spacecraft nose region. The nonablative nose of the second spacecraft thereby minimized flow field contamination. Comparisons of the probe measured density profiles with theoretical calculations are presented with discussion as to the probable cause of significant disagreement. Also discussed are the correlation of probe measurements with vehicle angle of attack motions and the good high altitude agreement between electron densities inferred from the probe measurements, VHF antenna measurements, and microwave reflectometer diagnostic measurements.

RNA encapsidation by SV40-derived nanoparticles follows a rapid two-state mechanism

PubMed Central

Kler, Stanislav; Asor, Roi; Li, Chenglei; Ginsburg, Avi; Harries, Daniel; Oppenheim, Ariella; Zlotnick, Adam; Raviv, Uri

2012-01-01

Remarkably, uniform virus-like particles self-assemble in a process that appears to follow a rapid kinetic mechanism. The mechanisms by which spherical viruses assemble from hundreds of capsid proteins around nucleic acid, however, are yet unresolved. Using Time-Resolved Small-Angle X-ray Scattering (TR-SAXS) we have been able to directly visualize SV40 VP1 pentamers encapsidating short RNA molecules (500 mers). This assembly process yields T = 1 icosahedral particles comprised of 12 pentamers and one RNA molecule. The reaction is nearly 1/3 complete within 35 milliseconds, following a two–state kinetic process with no detectable intermediates. Theoretical analysis of kinetics, using a master equation, shows that the assembly process nucleates at the RNA and continues by a cascade of elongation reactions in which one VP1 pentamer is added at a time, with a rate of approximately 109 M−1 s−1. The reaction is highly robust and faster than the predicted diffusion limit. The emerging molecular mechanism, which appears to be general to viruses that assemble around nucleic acids, implicates long-ranged electrostatic interactions. The model proposes that the growing nucleo-protein complex acts as an electrostatic antenna that attracts other capsid subunits for the encapsidation process. PMID:22329660

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.

The impact of base stacking on the conformations and electrostatics of single-stranded DNA.

PubMed

Plumridge, Alex; Meisburger, Steve P; Andresen, Kurt; Pollack, Lois

2017-04-20

Single-stranded DNA (ssDNA) is notable for its interactions with ssDNA binding proteins (SSBs) during fundamentally important biological processes including DNA repair and replication. Previous work has begun to characterize the conformational and electrostatic properties of ssDNA in association with SSBs. However, the conformational distributions of free ssDNA have been difficult to determine. To capture the vast array of ssDNA conformations in solution, we pair small angle X-ray scattering with novel ensemble fitting methods, obtaining key parameters such as the size, shape and stacking character of strands with different sequences. Complementary ion counting measurements using inductively coupled plasma atomic emission spectroscopy are employed to determine the composition of the ion atmosphere at physiological ionic strength. Applying this combined approach to poly dA and poly dT, we find that the global properties of these sequences are very similar, despite having vastly different propensities for single-stranded helical stacking. These results suggest that a relatively simple mechanism for the binding of ssDNA to non-specific SSBs may be at play, which explains the disparity in binding affinities observed for these systems. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

The parameterization of microchannel-plate-based detection systems

NASA Astrophysics Data System (ADS)

Gershman, Daniel J.; Gliese, Ulrik; Dorelli, John C.; Avanov, Levon A.; Barrie, Alexander C.; Chornay, Dennis J.; MacDonald, Elizabeth A.; Holland, Matthew P.; Giles, Barbara L.; Pollock, Craig J.

2016-10-01

The most common instrument for low-energy plasmas consists of a top-hat electrostatic analyzer (ESA) geometry coupled with a microchannel-plate-based (MCP-based) detection system. While the electrostatic optics for such sensors are readily simulated and parameterized during the laboratory calibration process, the detection system is often less well characterized. Here we develop a comprehensive mathematical description of particle detection systems. As a function of instrument azimuthal angle, we parameterize (1) particle scattering within the ESA and at the surface of the MCP, (2) the probability distribution of MCP gain for an incident particle, (3) electron charge cloud spreading between the MCP and anode board, and (4) capacitive coupling between adjacent discrete anodes. Using the Dual Electron Spectrometers on the Fast Plasma Investigation on NASA's Magnetospheric Multiscale mission as an example, we demonstrate a method for extracting these fundamental detection system parameters from laboratory calibration. We further show that parameters that will evolve in flight, namely, MCP gain, can be determined through application of this model to specifically tailored in-flight calibration activities. This methodology provides a robust characterization of sensor suite performance throughout mission lifetime. The model developed in this work is not only applicable to existing sensors but also can be used as an analytical design tool for future particle instrumentation.

THEMIS Observations of the Magnetopause Electron Diffusion Region: Large Amplitude Waves and Heated Electrons

NASA Technical Reports Server (NTRS)

Tang, Xiangwei; Cattell, Cynthia; Dombeck, John; Dai, Lei; Wilson, Lynn B. III; Breneman, Aaron; Hupack, Adam

2013-01-01

We present the first observations of large amplitude waves in a well-defined electron diffusion region based on the criteria described by Scudder et al at the subsolar magnetopause using data from one Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellite. These waves identified as whistler mode waves, electrostatic solitary waves, lower hybrid waves, and electrostatic electron cyclotron waves, are observed in the same 12 s waveform capture and in association with signatures of active magnetic reconnection. The large amplitude waves in the electron diffusion region are coincident with abrupt increases in electron parallel temperature suggesting strong wave heating. The whistler mode waves, which are at the electron scale and which enable us to probe electron dynamics in the diffusion region were analyzed in detail. The energetic electrons (approx. 30 keV) within the electron diffusion region have anisotropic distributions with T(sub e(right angle))/T(sub e(parallel)) > 1 that may provide the free energy for the whistler mode waves. The energetic anisotropic electrons may be produced during the reconnection process. The whistler mode waves propagate away from the center of the "X-line" along magnetic field lines, suggesting that the electron diffusion region is a possible source region of the whistler mode waves.

Tapered Optical Fiber Probe Assembled with Plasmonic Nanostructures for Surface-Enhanced Raman Scattering Application.

PubMed

Huang, Zhulin; Lei, Xing; Liu, Ye; Wang, Zhiwei; Wang, Xiujuan; Wang, Zhaoming; Mao, Qinghe; Meng, Guowen

2015-08-12

Optical fiber-Raman devices integrated with plasmonic nanostructures have promising potentials for in situ probing remote liquid samples and biological samples. In this system, the fiber probe is required to simultaneously demonstrate stable surface enhanced Raman scattering (SERS) signals and high sensitivity toward the target species. Here we demonstrate a generic approach to integrate presynthesized plasmonic nanostructures with tapered fiber probes that are prepared by a dipping-etching method, through reversed electrostatic attraction between the silane couple agent modified silica fiber probe and the nanostructures. Using this approach, both negatively and positively charged plasmonic nanostructures with various morphologies (such as Au nanosphere, Ag nanocube, Au nanorod, Au@Ag core-shell nanorod) can be stably assembled on the tapered silica fiber probes. Attributed to the electrostatic force between the plasmonic units and the fiber surface, the nanostructures do not disperse in liquid samples easily, making the relative standard deviation of SERS signals as low as 2% in analyte solution. Importantly, the detection sensitivity of the system can be optimized by adjusting the cone angle (from 3.6° to 22°) and the morphology of nanostructures assembled on the fiber. Thus, the nanostructures-sensitized optical fiber-Raman probes show great potentials in the applications of SERS-based environmental detection of liquid samples.

Aggrecan nanoscale solid-fluid interactions are a primary determinant of cartilage dynamic mechanical properties.

PubMed

Nia, Hadi Tavakoli; Han, Lin; Bozchalooi, Iman Soltani; Roughley, Peter; Youcef-Toumi, Kamal; Grodzinsky, Alan J; Ortiz, Christine

2015-03-24

Poroelastic interactions between interstitial fluid and the extracellular matrix of connective tissues are critical to biological and pathophysiological functions involving solute transport, energy dissipation, self-stiffening and lubrication. However, the molecular origins of poroelasticity at the nanoscale are largely unknown. Here, the broad-spectrum dynamic nanomechanical behavior of cartilage aggrecan monolayer is revealed for the first time, including the equilibrium and instantaneous moduli and the peak in the phase angle of the complex modulus. By performing a length scale study and comparing the experimental results to theoretical predictions, we confirm that the mechanism underlying the observed dynamic nanomechanics is due to solid-fluid interactions (poroelasticity) at the molecular scale. Utilizing finite element modeling, the molecular-scale hydraulic permeability of the aggrecan assembly was quantified (kaggrecan = (4.8 ± 2.8) × 10(-15) m(4)/N·s) and found to be similar to the nanoscale hydraulic permeability of intact normal cartilage tissue but much lower than that of early diseased tissue. The mechanisms underlying aggrecan poroelasticity were further investigated by altering electrostatic interactions between the molecule's constituent glycosaminoglycan chains: electrostatic interactions dominated steric interactions in governing molecular behavior. While the hydraulic permeability of aggrecan layers does not change across species and age, aggrecan from adult human cartilage is stiffer than the aggrecan from newborn human tissue.

Ripple formation on Si surfaces during plasma etching in Cl2

NASA Astrophysics Data System (ADS)

Nakazaki, Nobuya; Matsumoto, Haruka; Sonobe, Soma; Hatsuse, Takumi; Tsuda, Hirotaka; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

2018-05-01

Nanoscale surface roughening and ripple formation in response to ion incidence angle has been investigated during inductively coupled plasma etching of Si in Cl2, using sheath control plates to achieve the off-normal ion incidence on blank substrate surfaces. The sheath control plate consisted of an array of inclined trenches, being set into place on the rf-biased electrode, where their widths and depths were chosen in such a way that the sheath edge was pushed out of the trenches. The distortion of potential distributions and the consequent deflection of ion trajectories above and in the trenches were then analyzed based on electrostatic particle-in-cell simulations of the plasma sheath, to evaluate the angular distributions of ion fluxes incident on substrates pasted on sidewalls and/or at the bottom of the trenches. Experiments showed well-defined periodic sawtooth-like ripples with their wave vector oriented parallel to the direction of ion incidence at intermediate off-normal angles, while relatively weak corrugations or ripplelike structures with the wave vector perpendicular to it at high off-normal angles. Possible mechanisms for the formation of surface ripples during plasma etching are discussed with the help of Monte Carlo simulations of plasma-surface interactions and feature profile evolution. The results indicate the possibility of providing an alternative to ion beam sputtering for self-organized formation of ordered surface nanostructures.

Development of a Flyable Acousto-Optic Laser Beam Deflection System for a Head Up Display of the Future.

DTIC Science & Technology

Rayleigh criteria). The system was designed for stroke writing but was demonstrated with lissajous writing. The acousto - optic deflectors employed...The report describes a laser display which is to be used in a Head-Up Display of the future. The uniqueness of the display is that it uses acousto ... optic components for the modulation and deflection of the laser beam. As a result, there are no moving parts, which increases the reliability and life

AJ26 rocket engine testing news briefing

NASA Technical Reports Server (NTRS)

2010-01-01

Operators at NASA's John C. Stennis Space Center are completing modifications to the E-1 Test Stand to begin testing Aerojet AJ26 rocket engines in early summer of 2010. Modifications include construction of a 27-foot-deep flame deflector trench. The AJ26 rocket engines will be used to power Orbital Sciences Corp.'s Taurus II space vehicles to provide commercial cargo transportation missions to the International Space Station for NASA. Stennis has partnered with Orbital to test all engines for the transport missions.

Technical-economic feasibility of orbiting sunlight reflectors

NASA Astrophysics Data System (ADS)

Alferov, Z.; Minin, V.

1986-02-01

The use of deflectors in orbit as a means of providing artificial illumination is examined. Considerations of technical and economic feasibility are addressed. Three main areas of application are distinguished: reflecting sunlight onto the surface of the Earth; concentration of the flow of solar energy on an orbiting receiver; and retransmission of optical radiation. The advantages of the artificial Earth illumination application of the orbiting reflector scheme in terms of energy savings in lighting cities, and additional daylight time for critical periods of farming operations are discussed.

KSC-2013-3619

NASA Image and Video Library

2013-09-19

CAPE CANAVERAL, Fla. – At Launch Pad 39B at NASA’s Kennedy Space Center in Florida, the flame trench deflector located below and between the left and right crawlerway tracks has been removed. Pad B is being refurbished to support NASA’s Space Launch System and other launch vehicles. The Ground Systems Development and Operations, or GSDO, Program at Kennedy is leading the center’s transformation to safely handle a variety of rockets and spacecraft. For more information about GSDO, visit: http://go.nasa.gov/groundsystems. Photo credit: NASA/Jim Grossman

A 600 VOLT MULTI-STAGE, HIGH REPETITION RATE GAN FET SWITCH

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

Frolov, D.; Pfeffer, H.; Saewert, G.

Using recently available GaN FETs, a 600 Volt three- stage, multi-FET switch has been developed having 2 nanosecond rise time driving a 200 Ohm load with the potential of approaching 30 MHz average switching rates. Possible applications include driving particle beam choppers kicking bunch-by-bunch and beam deflectors where the rise time needs to be custom tailored. This paper reports on the engineering issues addressed, the design approach taken and some performance results of this switch.

An Automated System for Accurately Tracking and Measuring Multiple Targets in Six Dimensions

DTIC Science & Technology

2001-08-01

diffracted with good efficiency. The deflection medium is a crystal material TeO2 . The power of the electrical signal is 2W. The corresponding diffraction...between 50 MHz and 100 MHz. The acoustooptical deflector used a birefregent TeO2 single crystal as the ultrasonic medium where the light deflection take...pair of glass substrates with sufficient thickness (> 1 mm). The thick glass plate reduces the spatial resolution of the fiberoptic plate. To reduce

Shingle assembly

DOEpatents

Dinwoodie, Thomas L.

2007-02-20

A barrier, such as a PV module, is secured to a base by a support to create a shingle assembly with a venting region defined between the barrier and base for temperature regulation. The first edge of one base may be interengageable with the second edge of an adjacent base to be capable of resisting first and second disengaging forces oriented perpendicular to the edges and along planes oriented parallel to and perpendicular to the base. A deflector may be used to help reduce wind uplift forces.

Valley-isospin dependence of the quantum Hall effect in a graphene p-n junction

NASA Astrophysics Data System (ADS)

Tworzydło, J.; Snyman, I.; Akhmerov, A. R.; Beenakker, C. W. J.

2007-07-01

We calculate the conductance G of a bipolar junction in a graphene nanoribbon, in the high-magnetic-field regime where the Hall conductance in the p -doped and n -doped regions is 2e2/h . In the absence of intervalley scattering, the result G=(e2/h)(1-cosΦ) depends only on the angle Φ between the valley isospins ( =Bloch vectors representing the spinor of the valley polarization) at the two opposite edges. This plateau in the conductance versus Fermi energy is insensitive to electrostatic disorder, while it is destabilized by the dispersionless edge state which may exist at a zigzag boundary. A strain-induced vector potential shifts the conductance plateau up or down by rotating the valley isospin.

Plasma wave observations near the plasmapause with the S3-A satellite

NASA Technical Reports Server (NTRS)

Anderson, R. R.; Gurnett, D. A.

1972-01-01

The electric field noise phenomena is described which was observed by the S3-A spacecraft near the plasmapause during the magnetic storm of 16 to 17 December, 1971. The occurrence is noted of a region of intense, low frequency (20 Hz to 500 Hz) electrostatic noise bursts just outside the plasmapause boundary. These noise bursts occurred concurrent with the rapid decrease in 24.3 or = E or = 35.1 keV ring current protons mirroring near the equator during this storm and may be responsible for the pitch angle diffusion and loss of these particles. The characteristics of other phenomena, such as whistlers, ELF hiss, and banded chorus, observed near the plasmapause during this period are also discussed.

An integrated development facility for the calibration of low-energy charged particle flight instrumentation

NASA Technical Reports Server (NTRS)

Biddle, A. P.; Reynolds, J. M.

1985-01-01

A system was developed for the calibration and development of thermal ion instrumentation. The system provides an extended beam with usable current rates, approx. 1 pA/sq cm, at beam energies as low as 1 eV, with much higher values available with increasing energy. A tandem electrostatic and variable geometry magnetic mirror configuration within the ion source optimizes the use of the ionizing electrons. The system is integrated under microcomputer control to allow automatic control and monitoring of the beam energy and composition and the mass and angle-dependent response of the instrument under test. The system is pumped by a combination of carbon vane and cryogenic sorption roughing pumps and ion and liquid helium operating pumps.

Apparatus for raising or tilting a micromechanical structure

DOEpatents

Allen, James J [Albuquerque, NM

2008-09-09

An active hinge apparatus is disclosed which can be used to raise a micromechanical structure (e.g. a plate or micromirror) on a substrate. The active hinge apparatus utilizes one or more of teeth protruding outward from an axle which also supports the micromechanical structure on one end thereof. A rack is used to engage the teeth and rotate the axle to raise the micromechanical structure and tilt the structure at an angle to the substrate. Motion of the rack is provided by an actuator which can be a mechanically-powered actuator, or alternately an electrostatic comb actuator or a thermal actuator. A latch can be optionally provided in the active hinge apparatus to lock the micromechanical structure in an "erected" position.

Polarity control of h-BN nanoribbon edges by strain and edge termination.

PubMed

Yamanaka, Ayaka; Okada, Susumu

2017-03-29

We studied the polarity of h-BN nano-flakes in terms of their edge geometries, edge hydrogen termination, and uniaxial strain by evaluating their electrostatic potential using density functional theory. Our calculations have shown that the polarity of the nanoribbons is sensitive to their edge shape, edge termination, and uniaxial tensile strain. Polarity inversion of the ribbons can be induced by controlling the hydrogen concentration at the edges and the uniaxial tensile strain. The polarity inversion indicates that h-BN nanoribbons can exhibit non-polar properties at a particular edge hydrogen concentration and tensile strain, even though the nanoribbons essentially have polarity at the edge. We also found that the edge angle affects the polarity of nanoribbons with hydrogenated edges.

Sputtering of Metals by Mass-Analyzed N2(+) and N(+)

NASA Technical Reports Server (NTRS)

Bader, Michel; Witteborn, Fred C.; Snouse, Thomas W.

1961-01-01

Low-energy sputtering studies were conducted with the help of a specially designed ion accelerator. A high-intensity rf ion source was developed for use in conjunction with electrostatic acceleration and magnetic mass separation of ion beams in the 0 to 8 kev energy range. Beams of N(+) or N2(+) ions have been produced with intensities of 200 to 500 micro-a (approx. 1 sq cm in cross section) and energy half-widths of about 20 ev. The sputtering yields of five metals (Cu, Ni, Fe, Mo, and W) were obtained as a function of energy (0-8 kev), bombarding ion (N(+) and N2(+)), and angle of incidence (normal and 450). Results are presented and some of their theoretical implications are discussed.

In-situ determination of energy species yields of intense particle beams

DOEpatents

Kugel, H.W.; Kaita, R.

1983-09-26

Objects of the present invention are provided for a particle beam having a full energy component at least as great as 25 keV, which is directed onto a beamstop target, such that Rutherford backscattering, preferably near-surface backscattering occurs. The geometry, material composition and impurity concentration of the beam stop are predetermined, using any suitable conventional technique. The energy-yield characteristic response of backscattered particles is measured over a range of angles using a fast ion electrostatic analyzer having a microchannel plate array at its focal plane. The knee of the resulting yield curve, on a plot of yield versus energy, is analyzed to determine the energy species components of various beam particles having the same mass.

Hole-cyclotron instability in semiconductor quantum plasmas

NASA Astrophysics Data System (ADS)

Areeb, F.; Rasheed, A.; Jamil, M.; Siddique, M.; Sumera, P.

2018-01-01

The excitation of electrostatic hole-cyclotron waves generated by an externally injected electron beam in semiconductor plasmas is examined using a quantum hydrodynamic model. The quantum effects such as tunneling potential, Fermi degenerate pressure, and exchange-correlation potential are taken care of. The growth rate of the wave is analyzed on varying the parameters normalized by hole-plasma frequency, like the angle θ between propagation vector and B0∥z ̂ , speed of the externally injected electron beam v0∥k , thermal temperature of the electron beam τ, external magnetic field B0∥z ̂ that modifies the hole-cyclotron frequency, and finally, the semiconductor electron number density. The instability of the hole-cyclotron wave seeks its applications in semiconductor devices.

Independently tunable dual-band perfect absorber based on graphene at mid-infrared frequencies

DOE PAGES

Zhang, Yuping; Li, Tongtong; Chen, Qi; ...

2015-12-22

We design a dual-band absorber formed by combining two cross-shaped metallic resonators of different sizes within a super-unit-cell arranged in mirror symmetry. Simulations indicate that absorption efficiencies greater than 99% can be achieved at two different frequencies under normal incidence. We also employ a design scheme with graphene integration, which allows independent tuning of individual absorption frequencies by electrostatically changing the Fermi energy of the graphene layer. High absorbance is maintained over a wide incident angle range up to 50 degrees for both TE and TM polarizations. Thus, it enables a promising way to design electrically tunable absorbers, which maymore » contribute toward the realization of frequency selective detectors for sensing applications.« less

Design for an aberration corrected scanning electron microscope using miniature electron mirrors.

PubMed

Dohi, Hideto; Kruit, Pieter

2018-06-01

Resolution of scanning electron microscopes (SEMs) is determined by aberrations of the objective lens. It is well known that both spherical and chromatic aberrations can be compensated by placing a 90-degree bending magnet and an electron mirror in the beam path before the objective lens. Nevertheless, this approach has not led to wide use of these aberration correctors, partly because aberrations of the bending magnet can be a serious problem. A mirror corrector with two mirrors placed perpendicularly to the optic axis of an SEM and facing each other is proposed. As a result, only small-angle magnetic deflection is necessary to guide the electron beam around the top mirror to the bottom mirror and around the bottom mirror to the objective lens. The deflection angle, in the order of 50 mrad, is sufficiently small to avoid deflection aberrations. In addition, lateral dispersion at the sample plane can be avoided by making the deflection fields symmetric. Such a corrector system is only possible if the incoming beam can pass the top mirror at a distance in the order of millimeters, without being disturbed by the electric fields of electrodes of the mirror. It is proposed that condition can be satisfied with micro-scale electron optical elements fabricated by using MEMS technology. In the proposed corrector system, the micro-mirrors have to provide the exact negative spherical and chromatic aberrations for correcting the aberration of the objective lens. This exact tuning is accomplished by variable magnification between the micro-mirrors and the objective lens using an additional transfer lens. Extensive optical calculations are reported. Aberrations of the micro-mirrors were analyzed by numerical calculation. Dispersion and aberrations of the deflectors were calculated by using an analytical field model. Combination aberrations caused by the off-axis position of dispersive rays in the mirrors and objective lens were also analyzed. It is concluded that the proposed corrector system will be a promising candidate for simple and low-cost aberration correction in low-voltage SEMs. Copyright © 2018 Elsevier B.V. All rights reserved.

Compact electrostatic comb actuator

DOEpatents

Rodgers, M. Steven; Burg, Michael S.; Jensen, Brian D.; Miller, Samuel L.; Barnes, Stephen M.

2000-01-01

A compact electrostatic comb actuator is disclosed for microelectromechanical (MEM) applications. The actuator is based upon a plurality of meshed electrostatic combs, some of which are stationary and others of which are moveable. One or more restoring springs are fabricated within an outline of the electrostatic combs (i.e. superposed with the moveable electrostatic combs) to considerably reduce the space required for the actuator. Additionally, a truss structure is provided to support the moveable electrostatic combs and prevent bending or distortion of these combs due to unbalanced electrostatic forces or external loading. The truss structure formed about the moveable electrostatic combs allows the spacing between the interdigitated fingers of the combs to be reduced to about one micron or less, thereby substantially increasing the number of active fingers which can be provided in a given area. Finally, electrostatic shields can be used in the actuator to substantially reduce unwanted electrostatic fields to further improve performance of the device. As a result, the compact electrostatic comb actuator of the present invention occupies only a fraction of the space required for conventional electrostatic comb actuators, while providing a substantial increase in the available drive force (up to one-hundred times).

Unconventional superconductivity in magic-angle graphene superlattices.

PubMed

Cao, Yuan; Fatemi, Valla; Fang, Shiang; Watanabe, Kenji; Taniguchi, Takashi; Kaxiras, Efthimios; Jarillo-Herrero, Pablo

2018-04-05

The behaviour of strongly correlated materials, and in particular unconventional superconductors, has been studied extensively for decades, but is still not well understood. This lack of theoretical understanding has motivated the development of experimental techniques for studying such behaviour, such as using ultracold atom lattices to simulate quantum materials. Here we report the realization of intrinsic unconventional superconductivity-which cannot be explained by weak electron-phonon interactions-in a two-dimensional superlattice created by stacking two sheets of graphene that are twisted relative to each other by a small angle. For twist angles of about 1.1°-the first 'magic' angle-the electronic band structure of this 'twisted bilayer graphene' exhibits flat bands near zero Fermi energy, resulting in correlated insulating states at half-filling. Upon electrostatic doping of the material away from these correlated insulating states, we observe tunable zero-resistance states with a critical temperature of up to 1.7 kelvin. The temperature-carrier-density phase diagram of twisted bilayer graphene is similar to that of copper oxides (or cuprates), and includes dome-shaped regions that correspond to superconductivity. Moreover, quantum oscillations in the longitudinal resistance of the material indicate the presence of small Fermi surfaces near the correlated insulating states, in analogy with underdoped cuprates. The relatively high superconducting critical temperature of twisted bilayer graphene, given such a small Fermi surface (which corresponds to a carrier density of about 10 11 per square centimetre), puts it among the superconductors with the strongest pairing strength between electrons. Twisted bilayer graphene is a precisely tunable, purely carbon-based, two-dimensional superconductor. It is therefore an ideal material for investigations of strongly correlated phenomena, which could lead to insights into the physics of high-critical-temperature superconductors and quantum spin liquids.

Taurus II Stage Test Simulations: Using Large-Scale CFD Simulations to Provide Critical Insight into Plume Induced Environments During Design

NASA Technical Reports Server (NTRS)

Struzenberg, L. L.; West, J. S.

2011-01-01

This paper describes the use of targeted Loci/CHEM CFD simulations to evaluate the effects of a dual-engine first-stage hot-fire test on an evolving integrated launch pad/test article design. This effort was undertaken as a part of the NESC Independent Assessment of the Taurus II Stage Test Series. The underlying conceptual model included development of a series of computational models and simulations to analyze the plume induced environments on the pad, facility structures and test article. A pathfinder simulation was first developed, capable of providing quick-turn around evaluation of plume impingement pressures on the flame deflector. Results from this simulation were available in time to provide data for an ongoing structural assessment of the deflector. The resulting recommendation was available in a timely manner and was incorporated into construction schedule for the new launch stand under construction at Wallops Flight Facility. A series of Reynolds-Averaged Navier-Stokes (RANS) quasi-steady simulations representative of various key elements of the test profile was performed to identify potential concerns with the test configuration and test profile. As required, unsteady Hybrid-RANS/LES simulations were performed, to provide additional insight into critical aspects of the test sequence. Modifications to the test-specific hardware and facility structures thermal protection as well as modifications to the planned hot-fire test profile were implemented based on these simulation results.

Models of the strongly lensed quasar DES J0408-5354

NASA Astrophysics Data System (ADS)

Agnello, A.; Lin, H.; Buckley-Geer, L.; Treu, T.; Bonvin, V.; Courbin, F.; Lemon, C.; Morishita, T.; Amara, A.; Auger, M. W.; Birrer, S.; Chan, J.; Collett, T.; More, A.; Fassnacht, C. D.; Frieman, J.; Marshall, P. J.; McMahon, R. G.; Meylan, G.; Suyu, S. H.; Castander, F.; Finley, D.; Howell, A.; Kochanek, C.; Makler, M.; Martini, P.; Morgan, N.; Nord, B.; Ostrovski, F.; Schechter, P.; Tucker, D.; Wechsler, R.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Bertin, E.; Brooks, D.; Burke, D. L.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Dietrich, J. P.; Eifler, T. F.; Flaugher, B.; Fosalba, P.; García-Bellido, J.; Gaztanaga, E.; Gill, M. S.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Gschwend, J.; Gutierrez, G.; Honscheid, K.; James, D. J.; Kuehn, K.; Kuropatkin, N.; Li, T. S.; Lima, M.; Maia, M. A. G.; March, M.; Marshall, J. L.; Melchior, P.; Menanteau, F.; Miquel, R.; Ogando, R. L. C.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Schindler, R.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Smith, R. C.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Walker, A. R.

2017-12-01

We present detailed modelling of the recently discovered, quadruply lensed quasar J0408-5354, with the aim of interpreting its remarkable configuration: besides three quasar images (A,B,D) around the main deflector (G1), a fourth image (C) is significantly reddened and dimmed by a perturber (G2) which is not detected in the Dark Energy Survey imaging data. From lens models incorporating (dust-corrected) flux ratios, we find a perturber Einstein radius 0.04 arcsec ≲ RE, G2 ≲ 0.2 arcsec and enclosed mass Mp(RE, G2) ≲ 1.0 × 1010 M⊙. The main deflector has stellar mass log _{10}(M_{\\star }/M_{⊙})=11.49^{+0.46}_{-0.32}, a projected mass Mp(RE, G1) ≈ 6 × 1011 M⊙ within its Einstein radius RE, G1 = (1.85 ± 0.15) arcsec and predicted velocity dispersion 267-280 km s-1. Follow-up images from a companion monitoring campaign show additional components, including a candidate second source at a redshift between the quasar and G1. Models with free perturbers, and dust-corrected and delay-corrected flux ratios, are also explored. The predicted time-delays (ΔtAB = (135.0 ± 12.6) d, ΔtBD = (21.0 ± 3.5) d) roughly agree with those measured, but better imaging is required for proper modelling and comparison. We also discuss some lessons learnt from J0408-5354 on lensed quasar finding strategies, due to its chromaticity and morphology.

Quasar lenses and pairs in the VST-ATLAS and Gaia

NASA Astrophysics Data System (ADS)

Agnello, A.; Schechter, P. L.; Morgan, N. D.; Treu, T.; Grillo, C.; Malesani, D.; Anguita, T.; Apostolovski, Y.; Rusu, C. E.; Motta, V.; Rojas, K.; Chehade, B.; Shanks, T.

2018-04-01

We report on discovery results from a quasar lens search in the ATLAS-DR3 public footprint. Spectroscopic follow-up campaigns, conducted at the 2.6 m Nordic Optical Telescope (La Palma) and 3.6 m New Technology Telescope (La Silla) in 2016, yielded seven pairs of quasars exhibiting the same lines at the same redshift and monotonic flux ratios with wavelength (hereafter NIQs, nearly identical quasar pairs). Magellan spectra of A0140-1152 (01h40m03{^s.}0-11d52m19{^s.}0, zs = 1.807) confirm it as a lens with deflector at zl = 0.277 and Einstein radius θE = (0.73 ± 0.02) arcsec. Follow-up imaging of the NIQ A2213-2652 (22h13m38{^s.}4-26d52m27{^s.}1) reveals the deflector galaxy and confirms it as a lens. We show the use of spatial resolution from the Gaia mission to select lenses and list additional systems from a WISE-Gaia-ATLAS search, yielding three additional lenses (02h35m27{^s.}4-24d33m13{^s.}2, 02h59m33s-23d38m01{^s.}8, 01h46m32{^s.}9-11d33m39{^s.}0). The overall sample consists of 11 lenses/NIQs, plus three lenses known before 2016, over the ATLAS-DR3 footprint (≈3500 deg2). Finally, we discuss future prospects for objective classification of pair/NIQ/contaminant spectra.

Passive Rocket Diffuser Testing: Reacting Flow Performance of Four Second-Throat Geometries

NASA Technical Reports Server (NTRS)

Jones, Daniel R.; Allgood, Daniel C.; Saunders, Grady P.

2016-01-01

Second-throat diffusers serve to isolate rocket engines from the effects of ambient back pressure. As one of the nation's largest rocket testing facilities, the performance and design limitations of diffusers are of great interest to NASA's Stennis Space Center. This paper describes a series of tests conducted on four diffuser configurations to better understand the effects of inlet geometry and throat area on starting behavior and boundary layer separation. The diffusers were tested for a duration of five seconds with a 1455-pound thrust, LO2/GH2 thruster to ensure they each reached aerodynamic steady state. The effects of a water spray ring at the diffuser exits and a water-cooled deflector plate were also evaluated. Static pressure and temperature measurements were taken at multiple axial locations along the diffusers, and Computational Fluid Dynamics (CFD) simulations were used as a tool to aid in the interpretation of data. The hot combustion products were confirmed to enable the diffuser start condition with tighter second throats than predicted by historical cold-flow data or the theoretical normal shock method. Both aerodynamic performance and heat transfer were found to increase with smaller diffuser throats. Spray ring and deflector cooling water had negligible impacts on diffuser boundary layer separation. CFD was found to accurately capture diffuser shock structures and full-flowing diffuser wall pressures, and the qualitative behavior of heat transfer. However, the ability to predict boundary layer separated flows was not consistent.

Electrostatically screened, voltage-controlled electrostatic chuck

DOEpatents

Klebanoff, Leonard Elliott

2001-01-01

Employing an electrostatically screened, voltage-controlled electrostatic chuck particularly suited for holding wafers and masks in sub-atmospheric operations will significantly reduce the likelihood of contaminant deposition on the substrates. The electrostatic chuck includes (1) an insulator block having a outer perimeter and a planar surface adapted to support the substrate and comprising at least one electrode (typically a pair of electrodes that are embedded in the insulator block), (2) a source of voltage that is connected to the at least one electrode, (3) a support base to which the insulator block is attached, and (4) a primary electrostatic shield ring member that is positioned around the outer perimeter of the insulator block. The electrostatic chuck permits control of the voltage of the lithographic substrate; in addition, it provides electrostatic shielding of the stray electric fields issuing from the sides of the electrostatic chuck. The shielding effectively prevents electric fields from wrapping around to the upper or front surface of the substrate, thereby eliminating electrostatic particle deposition.