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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
DOE OSTI2026

AmeriFlux FLUXNET-1F US-xSP NEON Soaproot Saddle (SOAP)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xSP NEON Soaproot Saddle (SOAP). This is the FLUXNET version of the carbon flux data for the site US-xSP NEON Soaproot Saddle (SOAP) produced by applying the standard ONEFlux (1F) software. Site Description - The Soaproot Saddle is a complex terrain of coarse hills, steep slopes and narrow drainages. With an elevation of 3274 - 4537’ this site encompasses 1438 acres of mixed conifer forests that are experiencing high levels of mortality due to native Pine beetles. At the core of this site stands a 171’ tall flux tower that collects physical and chemical properties of atmosphere and related process. Soaproot Saddle also hosts an array of sensor measurements along with field observations collected by highly trained NEON staff. The automated instrument measurements and some of the terrestrial observational safor this field site are colocted with NEON's aquatic site, Upper Big Creek, which is located just north of Soaproot Saddle's site boundaries.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2023

Tungsten erosion and divertor leakage from the DIII-D SAS-VW tungsten-coated divertor in experiments with neon gas seeding

Collector probes have been used to examine tungsten divertor leakage in a variety of scenarios with low-Z impurity seeding during operation with the new tungsten-coated SAS-VW divertor in DIII-D. Measurements of tungsten deposition on collector probes inserted into the far Scrape-off-Layer (SOL) are used to deduce how efficiently tungsten leaks out of the closed, V-shaped divertor after it is eroded from the target surfaces. Qualitative differences in the tungsten deposition patterns across the collector probes provide clear experimental evidence that the SOL conditions depend on the low-Z impurity seeding conditions. These measurements show that in scenarios where neon gas is injected into the plasma, the tungsten divertor leakage and SOL transport depend on the poloidal location from which the neon is injected. In particular, neon injection from the Inner Midplane and Outer Midplane appear to each result in higher divertor leakage by a factor of 2 to 3 compared to cases with neon injection from either the SOL Crown or from the SAS-VW divertor itself.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xUN NEON University of Notre Dame Environmental Research Center (UNDE)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xUN NEON University of Notre Dame Environmental Research Center (UNDE). This is the FLUXNET version of the carbon flux data for the site US-xUN NEON University of Notre Dame Environmental Research Center (UNDE) produced by applying the standard ONEFlux (1F) software. Site Description - NEON's Domain 5 core site is located at the University of Notre Dame Environmental Research Center (UNDERC) East. Straddling the border between Northern Wisconsin and Michigan’s Upper Peninsula, the UNDERC property comprises approximately 7500 acres and is maintained as an environmental education and research facility. UNDERC also has 30 lakes comprising 1350 acres, including Crampton Lake, a NEON aquatics site. Region-wide logging for pine in the late 1800s and early to mid-1900's led to clear cutting of most forested areas on the property. The main parcel was donated to the University in the 1930s. Timber harvest continued into the 1950s and later, leaving a mixture of successional forest regrowth. Since the 1970s, the site has been minimally managed to maintain access for recreational, educational and research goals.

Network), NEON (National Ecological Observatory↗
DOE OSTI2025

A tale of two towers: comparing NEON and AmeriFlux data streams at Bartlett Experimental Forest

Long-term ecological data are essential for detecting impacts of climate change and other global change factors, and for making informed predictions about future change. However, long-term measurements are rarely replicated at the site level, which raises questions about their representativeness. We used a multiscale approach to evaluate the agreement of parallel observations from AmeriFlux and NEON (National Ecological Observatory Network) towers at Bartlett Experimental Forest, New Hampshire, USA. The two towers are separated by a horizontal distance of 93 m. Here, we focused our analysis on standard meteorological variables; fluxes of CO 2 , sensible heat, and latent heat measured by eddy covariance; and phenology derived from PhenoCam imagery. Results suggest excellent agreement between AmeriFlux and NEON in meteorology and phenology, and good agreement in fluxes at the half-hourly scale. However, large disagreements in CO 2 and latent heat fluxes occurred at the annual scale, with implications especially for the forest carbon balance. The AmeriFlux tower measurements indicate a site that is close to carbon-neutral (-8 ± 65 g C m -2 y -1 , mean ± 1 SD), whereas the NEON tower measurements indicate a forest that is a carbon sink (-137 ± 10 g C m -2 y -1 ). Causes of this disagreement may include measurement height (26 m vs. 35 m), which resulted in different flux footprints being measured by the two towers, and differences in the flux measurement systems. Our results suggest the need for caution when attempting to merge long-term flux data from two different measurement platforms, and when using measurements from any one measurement platform to inform decision-making on issues related to carbon accounting or natural climate solutions.

Carbon cycle↗
DOE OSTI2022

Measurement and simulation of small cryogenic neon pellet Ne-I 640 nm photon efficiency during ablation in DIII-D plasma

Small (~1 mm) neon pellet fragments are fired into DIII-D H-mode plasmas, and resulting trajectory-averaged photon efficiencies (neutral neon ionization events for every photon emitted) of S/XB ≈ 85 are estimated for Ne-I 640 nm by dividing the estimated initial pellet fragment mass by the measured number of emitted Ne-I photons. The experiments are modeled by running the Lagrangian particle (LP) fluid/magneto-hydrodynamic pellet code to estimate axial ablation plume neon density profiles and temperature profiles at each pellet position. These solutions are then fed into the PrismSPECT collisional-radiative code, which calculates resulting neon charge states and photon emission rates, giving a profile-average of S/XB ≈ 109. The burnthrough plasma minor radius predicted by LP (ρ ≈ 0.63) is reasonably close to the experimental observation ρ ≈ 0.6. Furthermore, the modeling indicates that local S/XB is not constant along the pellet trajectory but tends to increase with increasing ablation rate. Non-equilibrium kinetics are predicted to be very important, while line trapping is predicted to be relatively unimportant (for Ne-I 640 nm S/XB).

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2021

3D radiation, density, and MHD structures following neon shattered pellet injection into stable DIII-D Super H-mode discharges

Six nominally repeat neon shattered pellet injection (SPI) shutdowns of stable DIII-D Super H-modes are studied to understand the 3D properties of the radiation and impurity transport. The radiation efficiency and radiation peaking determine whether first wall melting is expected following disruption mitigation in ITER. Previous studies make use of axisymmetric approximations to infer radiation efficiencies, but validating the high efficiency required by ITER necessitates improved accuracy, and this work contributes by exploring the 3D radiation and density structures that will inform forward modeling. When the neon shatter plume produced by the SPI reaches the plasma edge, m/n = 3/1 and 2/1 island O-points are observed to align with the injection trajectory in five out of six cases, suggesting that the injected material seeds the island O-points. Field aligned neon structures emitting Ne-I line radiation drift at 1 km/s in the ion diamagnetic drift direction during the pre-TQ, tracking the motion of the m/n = 2/1 island O-point. Neon fragments penetrate to the q = 2 surface by the time of the TQ. Techniques to constrain the 3D emissivity are explored, and one method constrains a 3D flux tube that is consistent with the radiation data, and when mapped to the interferometers, intersects the lasers that measure the highest density. The resulting structure derived from the radiation measurements exists near the 2/1 island X-point. In five repeatable discharges, the peak of the radiation in the toroidal direction exists in a 120° toroidal sector where the injection occurs, in contrast with the outlier discharge where the toroidal peak exists in the complementary 240° toroidal sector far from the injector, and where a 50% lower density rise is observed. In conclusion, the n = 1 phase behavior is markedly different in the outlier discharge, suggesting a possible dependence of the radiation structure and the assimilation efficiency on MHD.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
DOE OSTI2024

Interpretive modeling of tungsten divertor leakage during experiments with neon gas seeding

Abstract Many existing and future tokamaks with tungsten divertors operate, or will operate, with low- Z impurity seeding, but the direct effect of these seeded impurities on tungsten Scrape-off-Layer (SOL) transport has not been explored in detail. This paper reports on a DIII-D experiment designed to test how tungsten divertor leakage from the Small-Angle Slot V-Shaped, tungsten-coated divertor is impacted by neon seeding at a variety of injection rates and poloidal injection locations. Measurements from the experiment show an inverse relationship between the neon injection rate and the tungsten core penetration factor. Interpretive modeling is performed with a combination of the SOLPS-ITER and DIVIMP codes to assess the underlying tungsten behavior. The modeling results show that the reduction in tungsten divertor leakage is driven by both an increase in the divertor collisionality as well as a reduction in the ion temperature gradient near the divertor target. Collisions between low- Z impurities and tungsten impurities are found to have a significant impact on the tungsten SOL transport, such that ignoring the low- Z impurity collisional effects on the tungsten transport can result in an overestimate of the divertor leakage by an order-of-magnitude. Given the importance of these localized interactions, neon seeding from the closed, slot-like divertor has a clear advantage in being able to reduce tungsten divertor leakage without the high levels of neon core contamination that occur when seeding from other poloidal locations.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1974

A neon-E-rich phase in the Orgueil carbonaceous chondrite

Attention is given to a procedure for separating a silicate fraction which contains large amounts of neon-E from the carbonaceous chondrite Orgueil. In this fraction a 20Ne/22Ne ratio of 4.56 is measured. The obtained data support the hypothesis that neon-E might be associated with interstellar dust grains of the type not fully homogenized with the solar system and which retain some of their trapped neon. Neon results in a three-isotope diagram are presented.

Eberhardt, P.↗
NASA NTRS1983

Cosmogenic neon from precompaction irradiation of Kapoeta and Murchison

Neon from hand-picked Murchison and Kapoeta grains, selected on the basis of the presence or absence of solar flare particle tracks, was analyzed in order to delineate the precompaction history of this material. The irradiated grains showed large enrichments of cosmogenic neon relative to the unirradiated grains. Galactic cosmic ray (GCR) exposure ages for the unirradiated grains yield the nominal values reported for the recent exposure history of these meteorites. Apparent minimum precompaction galactic exposure ages of 28 m.y. and 56 m.y. would have been obtained for Murchison and Kapoeta, respectively, if the cosmogenic effects in the irradiated grains were due to GCR irradiation. Since this seems unreasonably long, the cosmogenic neon in the irradiated grains may be due to spallation by solar cosmic rays. This, however, would require a more active early sun. The isotopic composition of the cosmogenic neon in these grains suggests a harder energy spectrum than is characteristic of present solar flares. Lack of apparent solar wind effects may require some kind of shielding, such as nebular gas.

Caffee, M. W.↗
NASA NTRS1993

Elemental abundances of flaring solar plasma - Enhanced neon and sulfur

Elemental abundances of two flares observed with the SMM Flat Crystal Spectrometer are compared and contrasted. The first had a gradual rise and a slow decay, while the second was much more impulsive. Simultaneous spectra of seven bright soft X-ray resonance lines provide information over a broad temperature range and are available throughout both flares, making these events unique in the SMM data base. For the first flare, the plasma seemed to be characterized by coronal abundances but, for the second, the plasma composition could not be coronal, photospheric, or a linear combination of both. A good differential emission measure fit required enhanced neon such that Ne/O = 0.32 +/- 0.02, a value which is inconsistent with the current models of coronal abundances based on the elemental first-ionization potential. Similar values of enhanced neon are found for flaring plasma observed by the SMM gamma-ray spectrometer, in (He-3)-rich solar energetic particle events, and in the decay phase of several long duration soft X-ray events. Sulfur is also enhanced in the impulsive flare, but not as dramatically as neon. These events are compared with two models which attempt to explain the enhanced values of neon and sulfur.

Schmelz, J. T.↗
NASA NTRS2008

Neon as a Buffer Gas for a Mercury-Ion Clock

A developmental miniature mercury-ion clock has stability comparable to that of a hydrogen-maser clock. The ion-handling components are housed in a sealed vacuum tube, wherein a getter pump is used to maintain the partial vacuum, and the evacuated tube is backfilled with mercury vapor in a buffer gas. Neon was determined to be the best choice for the buffer gas: The pressure-induced frequency pulling by neon was found to be only about two-fifths of that of helium. Furthermore, because neon diffuses through solids much more slowly than does helium, the operational lifetime of a tube backfilled with neon could be considerably longer than that of a tube backfilled with helium.

Prestage, John↗
DOE OSTI2025

AmeriFlux FLUXNET-1F US-xNW NEON Niwot Ridge Mountain Research Station (NIWO)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xNW NEON Niwot Ridge Mountain Research Station (NIWO). This is the FLUXNET version of the carbon flux data for the site US-xNW NEON Niwot Ridge Mountain Research Station (NIWO) produced by applying the standard ONEFlux (1F) software. Site Description - The Niwot Ridge sits approximately 27 km west of Boulder, Colorado, and 6 km east of the Continental Divide. Topography, climate, and biota of the site are representative of Rocky Mountain alpine ecosystems, including extensive alpine tundra (mostly herbs, some shrubs and scree) and subalpine coniferous forests (Abies lasciocarpa and Picea engelmanii at higher elevations), talus slopes, wetlands and a variety of glacial landforms. Characterized by cold and relatively long winters, Niwot Ridge has an average annual temperature of 1.5°C and average annual precipitation of 800 mm. Most precipitation falls as snow and summer precipitation falls primarily during afternoon thunderstorms. Located on the eastern side of the Continental Divide at 3,000-3,500 m elevation, the site best captures chemical inputs produced along the Front Range and is well situated to observe other east/west flows across the Southern Rockies in conjunction with other NEON sites.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2025

AmeriFlux FLUXNET-1F US-xWR NEON Wind River Experimental Forest (WREF)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xWR NEON Wind River Experimental Forest (WREF). This is the FLUXNET version of the carbon flux data for the site US-xWR NEON Wind River Experimental Forest (WREF) produced by applying the standard ONEFlux (1F) software. Site Description - Located in an old growth Pacific Northwest forest west of the Cascade Range, Wind River Experimental Forest has a rich history of research and timber management since the early 1900s. The area is best known for its old-growth forests of Douglas-fir and western hemlock. Data collected at this site provides an interesting comparison to NEON’s ABBY site which is located Yacolt Burn State Forest, a relatively young growth industrial timber production forest.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2025

AmeriFlux FLUXNET-1F US-xRN NEON Oak Ridge National Lab (ORNL)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xRN NEON Oak Ridge National Lab (ORNL). This is the FLUXNET version of the carbon flux data for the site US-xRN NEON Oak Ridge National Lab (ORNL) produced by applying the standard ONEFlux (1F) software. Site Description - Oak Ridge National Laboratory (ORNL) is located at the U.S. Department of Energy's Oak Ridge Reservation in Roane County, Tennessee. The ORNL reservation is situated within the borders of five parallel ridges and valleys to the north of the Clinch River that are part of the Ridge-and-Valley Appalachians physiographic province (Environmental Sciences Division n.d.). The NEON tower site and Walker Branch aquatic site at ORNL are located within the Walker Branch Watershed, a 100 ha area that has served as the site for long-term environmental studies by the Environmental Sciences Division at ORNL, NOAA, and many visiting university researchers.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2025

AmeriFlux FLUXNET-1F PR-xLA NEON Lajas Experimental Station (LAJA)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site PR-xLA NEON Lajas Experimental Station (LAJA). This is the FLUXNET version of the carbon flux data for the site PR-xLA NEON Lajas Experimental Station (LAJA) produced by applying the standard ONEFlux (1F) software. Site Description - The NEON Lajas Experimental Station (LAJA) site is located on the southwest corner of the main island of Puerto Rico in a experimental range. This is a grassland site that is periodically grazed by cattle.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2025

AmeriFlux FLUXNET-1F US-xPU NEON Pu'u Maka'ala Natural Area Reserve (PUUM)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xPU NEON Pu'u Maka'ala Natural Area Reserve (PUUM). This is the FLUXNET version of the carbon flux data for the site US-xPU NEON Pu'u Maka'ala Natural Area Reserve (PUUM) produced by applying the standard ONEFlux (1F) software. Site Description - NEON's PUUM field site is located in the Pu'u Maka'ala Natural Area Reserve (NAR) on the eastern side of Hawaii’s “Big Island,” managed by the Hawaii Division of Forestry and Wildlife (DOFAW). More than 18,000 acres in size, the NAR is home to a rainforest with many native species, some of them endangered. It was established to protect some of the Big Island’s best wet native forest and unique geologic features.

Network), NEON (National Ecological Observatory [N↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xCP NEON Central Plains Experimental Range (CPER)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xCP NEON Central Plains Experimental Range (CPER). This is the FLUXNET version of the carbon flux data for the site US-xCP NEON Central Plains Experimental Range (CPER) produced by applying the standard ONEFlux (1F) software. Site Description - Central Plains Experimental Range (CPER) site in north central Colorado. CPER served as part of the Shortgrass Steppe LTER from 1982-2014 and is now home to a fully instrumented NEON site and a wealth of relevant historical data as well as ongoing collections of complementary data(i.e. airborne remote sensing, soil temperature and moisture, phenology measurements, plant biomass and more)

Network), NEON (National Ecological Observatory↗
DOE OSTI2023

AmeriFlux FLUXNET-1F US-xDC NEON Dakota Coteau Field School (DCFS)

This is the AmeriFlux Management Project (AMP) created FLUXNET-1F version of the carbon flux data for the site US-xDC NEON Dakota Coteau Field School (DCFS). This is the FLUXNET version of the carbon flux data for the site US-xDC NEON Dakota Coteau Field School (DCFS) produced by applying the standard ONEFlux (1F) software. Site Description - The Dakota Coteau Field School (DCFS) and Prairie Lake (PRLA) field sites are co-located in an agricultural area used primarily for cattle grazing, just a few miles east of the Woodworth and Prairie Pothole sites at the Chase Lake National Wildlife Refuge. DCFS covers 7.8 km2 (3 square miles) of grazing land in Stutsman County, ND, between the tiny communities of Pingree and Woodworth. The population here is sparse, but the land has been transformed by agricultural activities over the last 150 years. The field site has been used only for grazing, but other land in the surrounding area has been converted to corn and soybean production. DCFS is located in an area known as the "Prairie Pothole Region," a band of tall and mixed prairie that stretches across parts of North and South Dakota, Minnesota and the Canadian provinces of Alberta, Saskatchewan and Manitoba. Historically, this area supported tall to mid-height prairie grasses, including blue gamma and green needlegrass. The land here is pocked by thousands of depressions left behind by glaciers 10,000 years ago, resulting in a series of small lakes and wetland areas known as prairie potholes. These potholes receive most of their water from spring snowmelt and are a primary source of groundwater recharge for the region. NEON data will help researchers monitor the effects of climate change on the Northern Plains ecosystem. Over the last 30 years, the hydrological cycle in the plains has changed dramatically, trending wetter overall and diverging from the historical ten-year cycles. Temperatures are also rising, leading to changes in plant phenology cycles and species distribution that could negatively impact migratory bird populations and other animal species.

Network), NEON (National Ecological Observatory↗