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Wright, J.

Publications and source records attributed to Wright, J..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2014

A system for trapping barium ions in a microfabricated surface trap

We have developed a vacuum chamber and control system for rapid testing of microfabricated surface ion traps. Our system is modular in design and is based on an in-vacuum printed circuit board with integrated filters. We have used this system to successfully trap and cool barium ions and have achieved ion ‘dark' lifetimes of 31.6 s ± 3.4 s with controlled shuttling of ions. We provide a detailed description of the ion trap system including the in-vacuum materials used, control electronics and neutral atom source. We discuss the challenges presented in achieving a system which can work reliably over two years of operations in which the trap under test was changed at least 10 times.

43 PARTICLE ACCELERATORS↗
DOE OSTI2014

Joint Exposure to Chemical and Nonchemical Neurodevelopmental Stressors in U.S. Women of Reproductive Age in NHANES

Lead (Pb) and methyl mercury (MeHg) are well established neurodevelopmental toxicants (NDTs), but joint exposure to chemical and nonchemical (e.g., maternal stress) stressors has rarely been considered. We characterized exposure to Pb, MeHg and a measure of physiological dysregulation associated with chronic stress and examined race/ethnicity as a predictor of joint NDT exposure. Using data from the 2003-2004 NHANES, potential chronic stress exposure was estimated using allostatic load (AL), a quantitative measure of physiological dysregulation. A Hazard Index was calculated for joint exposure to Pb and MeHg (HI NDT ). Logistic regression was used to assess the relationship between an indicator of elevated joint NDT exposures (HI NDT > 1) and race/ethnicity. The multivariate model was stratified by AL groups to examine effect measure modification. African American (adjusted odds ratio [OR] [95% confidence interval] = 2.2 [1.4, 3.3]) and Mexican American (1.4 [0.7, 2.6]) women were more likely to have an HI NDT > 1 compared to Caucasian women. Chronic stress was identified as an effect measure modifier with the largest ORs among women with high AL scores (African Americans = 4.3 [2.0, 9.5]; Mexican Americans = 4.2 [1.3, 14.1]). Chronic stress was found to modify the association between elevated joint NDT exposure and race/ethnicity, highlighting the importance of evaluating chemical and nonchemical stressor exposures leading to a common endpoint.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2013

IN-LINE CHEMICAL SENSOR DEPLOYMENT IN A TRITIUM PLANT

The Savannah River Tritium Plant (TP) relies on well understood but aging sensor technology for process gas analysis. Though new sensor technologies have been brought to various readiness levels, the TP has been reluctant to install technologies that have not been tested in tritium service. This gap between sensor technology development and incorporating new technologies into practical applications demonstrates fundamental challenges that exist when transitioning from status quo to state-of-the-art in an extreme environment such as a tritium plant. These challenges stem from three root obstacles: 1) The need for a comprehensive assessment of process sensing needs and requirements; 2) The lack of a pick-list of process-compatible sensor technologies; and 3) The need to test technologies in a tritium-contaminated process environment without risking production. At Savannah River, these issues are being addressed in a two phase project. In the first phase, TP sensing requirements were determined by a team of process experts. Meanwhile, Savannah River National Laboratory sensor experts identified candidate technologies and related them to the TP processing requirements. The resulting roadmap links the candidate technologies to actual plant needs. To provide accurate assessments of how a candidate sensor technology would perform in a contaminated process environment, an instrument demonstration station was established within a TP glove box. This station was fabricated to TP process requirements and designed to handle high activity samples. The combination of roadmap and demonstration station provides the following assets: Creates a partnership between the process engineers and researchers for sensor selection, maturation, and insertion, Selects the right sensors for process conditions Provides a means for safely inserting new sensor technology into the process without risking production, and Provides a means to evaluate off normal occurrences where and when they occur. This paper discusses the process to identify and demonstrate new sensor technologies for the Savannah River TP.

07 ISOTOPE AND RADIATION SOURCES↗
DOE OSTI2013

Fast wave heating in the NSTX-Upgrade device

NSTX-Upgrade will operate with toroidal magnetic fields (B T) up to 1 T, nearly twice the value used in the experiments on NSTX, and the available NBI power will be doubled. The doubling of B T while retaining the 30 MHz RF source frequency has moved the heating regime from the high harmonic fast wave (HHFW) regime used in NSTX to the mid harmonic fast wave (MHFW) regime. By making use of the full wave code AORSA, this work shows that direct ion damping (mainly by thermal ions localized at the 5th harmonic resonance) might be significant in NSTX-Upgrade under TRANSP predicted full performance conditions and the electron and ion absorption is sensitive to the ratio of electron and ion temperature. Launching at high toroidal wave number appears to be one way to significantly reduce the ion damping. By using the extended AORSA code, which includes a detailed description of the scrape-off layer in the field solutions, we found a large electric field amplitude outside of the last closed flux surface as previously seen in NSTX from AORSA simulations (D. L. Green, et al, Phys. Rev. Lett. 107, 145001 (2011)). Preliminary results by introducing a collision damping in the scrape-off layer in the AORSA code to represent a damping process are presented, showing for the first time absorbed power in the scrape-off layer.

Bertelli, Nicola↗
NASA NTRS2005

Driving on the surface of Mars with the rover sequencing and visualization program

Operating a rover on Mars is not possible using teleoperations due to the distance involved and the bandwith limitations. To operate these rovers requires sophisticated tools to make operators knowledgeable of the terrain, hazards, features of interest, and rover state and limitations, and to support building command sequences and rehearsing expected operations. This paper discusses how the Rover Sequencing and Visualization program and a small set of associated tools support this requirement.

autonomy↗
NASA NTRS2004

Terrain Modelling for Immersive Visualization for the Mars Exploration Rovers

Immersive environments are being used to support mission operations at the Jet Propulsion Laboratory. This technology contributed to the Mars Pathfinder Mission in planning sorties for the Sojourner rover and is being used for the Mars Exploration Rover (MER) missions. The stereo imagery captured by the rovers is used to create 3D terrain models, which can be viewed from any angle, to provide a powerful and information rich immersive visualization experience. These technologies contributed heavily to both the mission success and the phenomenal level of public outreach achieved by Mars Pathfinder and MER. This paper will review the utilization of terrain modelling for immersive environments in support of MER.

immersive environments↗
NASA NTRS2002

Immersive environment technologies for planetary exploration with applications for mixed reality

Immersive environments are successfully being used to support mission operations at JPL. This technology contributed to the Mars Pathfinder Mission in planning sorties for the Sojourner rover. Results and operational experiences with these tools are being incorporated into the development of the second generation of mission planning tools.

visualization rover system ground system Mars imme↗
NASA NTRS2000

Low Frequency Radar Sensor Observations of Tropical Forests in the Panama Canal Area

A synthetic aperture radar sensor operating in 5 bands between 80 and 120 MHz was flown over forested areas in the canal zone of the Republic of Panama in an experiment to measure biomass in heavy tropical forests. The sensor is a pulse coherent SAR flown on a small aircraft and oriented straight down. The doppler history is processed to collect data on the ground in rectangular cells of varying size over a range of incidence angles fore and aft of nadir (+45 to - 45 degrees). Sensor data consists of 5 frequency bands with 20 incidence angles per band. Sensor data for over 12+ sites were collected with forest stands having biomass densities ranging from 50 to 300 tons/ha dry above ground biomass. Results are shown exploring the biomass saturation thresholds using these frequencies, the system design is explained, and preliminary attempts at data visualization using this unique sensor design are described.

Imhoff, M. L.↗