scholarly journals Predicting capsule fill weight from in-situ powder density measurements using terahertz reflection technology

2019 ◽  
Vol 1 ◽  
pp. 100004 ◽  
Author(s):  
Sandra Stranzinger ◽  
Eva Faulhammer ◽  
Jingyi Li ◽  
Runqiao Dong ◽  
J. Axel Zeitler ◽  
...  
Keyword(s):  
Density Measurements ◽  
Powder Density

scholarly journals Density structures inside the plasmasphere: Cluster observations

2004 ◽  
Vol 22 (7) ◽  
pp. 2577-2585 ◽  
Author(s):  
F. Darrouzet ◽  
P. M. E. Décréau ◽  
J. De Keyser ◽  
A. Masson ◽  
D. L. Gallagher ◽  
...  
Keyword(s):  
Density Gradient ◽  
Time Delays ◽  
Statistical Study ◽  
Outer Boundary ◽  
Normal Velocity ◽  
Density Profiles ◽  
Density Measurements ◽  
Image Satellite ◽  
Electron Density Profiles

Abstract. The electron density profiles derived from the EFW and WHISPER instruments on board the four Cluster spacecraft reveal density structures inside the plasmasphere and at its outer boundary, the plasmapause. We have conducted a statistical study to characterize these density structures. We focus on the plasmasphere crossing on 11 April 2002, during which Cluster observed several density irregularities inside the plasmasphere, as well as a plasmaspheric plume. We derive the density gradient vectors from simultaneous density measurements by the four spacecraft. We also determine the normal velocity of the boundaries of the plume and of the irregularities from the time delays between those boundaries in the four individual density profiles, assuming they are planar. These new observations yield novel insights about the occurrence of density irregularities, their geometry and their dynamics. These in-situ measurements are compared with global images of the plasmasphere from the EUV imager on board the IMAGE satellite.

scholarly journals Stratification observed by the in situ plasma density measurements from the Swarm satellites

2020 ◽  
Vol 38 (2) ◽  
pp. 517-526
Author(s):  
Xiuying Wang ◽  
Wanli Cheng ◽  
Zihan Zhou ◽  
Dehe Yang ◽  
Jing Cui ◽  
...  
Keyword(s):  
Plasma Density ◽  
Continuous Distribution ◽  
Direct Analysis ◽  
Density Measurements ◽  
Equatorial Ionization Anomaly ◽  
Swarm Satellites ◽  
Plasma Peak ◽  
First Time ◽  
New Discovery

Abstract. The stratification phenomenon is investigated using the simultaneous in situ plasma density measurements obtained by the Swarm satellites orbiting at different altitudes above the F2 peak. For the first time, the continuous distribution morphology and the exact locations are obtained for the nighttime stratification, which show that the stratification events are centered at the EIA (equatorial ionization anomaly) trough and extend towards the two EIA crests, with the most significant part being located at the EIA trough. Another new discovery is the stratification in southern mid-latitudes; stratification events in this region are located on a local plasma peak sandwiched by two lower density strips covering all the longitudes. The formation mechanism of the stratification for the two latitudinal regions is discussed, but the stratification mechanism in southern mid-latitudes remains an unsolved problem. Highlights. This paper addresses the following: first application of in situ plasma densities for the direct analysis of the stratification in F2 layer, refined features of the exact location and continuous morphology for the stratification phenomenon, a new discovery of stratification covering all longitudes in southern mid-latitudes.

scholarly journals Stratification observed by the in situ measurements from the Swarm satellites

2020 ◽  
Author(s):  
Xiuying Wang ◽  
Wanli Cheng ◽  
Zihan Zhou ◽  
Dehe Yang ◽  
Jing Cui ◽  
...  
Keyword(s):  
Unsolved Problem ◽  
Continuous Distribution ◽  
Density Measurements ◽  
Equatorial Ionization Anomaly ◽  
Swarm Satellites ◽  
Plasma Peak ◽  
First Time ◽  
Different Altitudes ◽  
New Discovery

Abstract. Stratification phenomenon is investigated using the simultaneous in situ plasma density measurements obtained by the Swarm satellites orbiting at different altitudes above F2 peak. For the first time, the continuous distribution morphology and the exact locations are obtained for the nighttime stratification, which show that the stratification events are centered at the EIA (equatorial ionization anomaly) trough and extend towards the two EIA crests with the most significant part being located at the EIA trough. Another new discovery is the stratification in southern mid-latitudes; stratification events in this region are located on a local plasma peak sandwiched by two lower density strips covering all the longitudes. The formation mechanism of the stratification for the two latitudinal regions is discussed, but the stratification mechanism in southern mid-latitudes remains an unsolved problem.

scholarly journals The first in situ electron temperature and density measurements of the Martian nightside ionosphere

2015 ◽  
Vol 42 (21) ◽  
pp. 8854-8861 ◽  
Author(s):  
C. M. Fowler ◽  
L. Andersson ◽  
R. E. Ergun ◽  
M. Morooka ◽  
G. Delory ◽  
...  
Keyword(s):  
Electron Temperature ◽  
Density Measurements

scholarly journals Greenland annual accumulation along the EGIG line, 1959–2004, from ASIRAS airborne radar and detailed neutron-probe density measurements

2015 ◽  
Vol 9 (6) ◽  
pp. 6791-6828
Author(s):  
T. B. Overly ◽  
R. L. Hawley ◽  
V. Helm ◽  
E. M. Morris ◽  
R. N. Chaudhary
Keyword(s):  
Mesoscale Model ◽  
Snow Accumulation ◽  
Accumulation Rates ◽  
Radar Altimeter ◽  
Density Profiles ◽  
Density Measurements ◽  
Fifth Generation ◽  
Neutron Probe ◽  
Airborne Sar

Abstract. We report annual snow accumulation rates from 1959 to 2004 along a 250 km segment of the Expéditions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and detailed neutron-probe (NP) density profiles. ASIRAS-NP accumulation rates are not statistically different (C.I. 95 %) from in situ EGIG accumulation measurements from 1985 to 2004. Below 3000 m elevation, ASIRAS-NP increases by 20 % for the period 1995 to 2004 compared to 1985 to 1994. Above 3000 m elevation, accumulation increases by 13 % for 1995–2004 compared to 1985–1994. Model snow accumulation results from the calibrated Fifth Generation Mesoscale Model modified for polar climates (Polar MM5) underestimate mean annual accumulation by 16 % compared to ASIRAS-NP from 1985 to 2004. We test radar-derived accumulation rates sensitivity to density using modelled density profiles in place of detailed NP data. ASIRAS radar layers combined with Herron and Langway (1980) model density profiles (ASIRAS-HL) produce accumulation rates within 3.5 % of ASIRAS-NP estimates. We suggest using Herron and Langway (1980) density profiles to calibrate radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements, such as those observed by the IceBridge campaign.

scholarly journals Greenland annual accumulation along the EGIG line, 1959–2004, from ASIRAS airborne radar and neutron-probe density measurements

2016 ◽  
Vol 10 (4) ◽  
pp. 1679-1694 ◽  
Author(s):  
Thomas B. Overly ◽  
Robert L. Hawley ◽  
Veit Helm ◽  
Elizabeth M. Morris ◽  
Rohan N. Chaudhary
Keyword(s):  
Climate Models ◽  
Regional Climate ◽  
Regional Climate Models ◽  
Snow Accumulation ◽  
Accumulation Rates ◽  
Radar Altimeter ◽  
Density Profiles ◽  
Density Measurements ◽  
Neutron Probe

Abstract. We report annual snow accumulation rates from 1959 to 2004 along a 250 km segment of the Expéditions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and high resolution neutron-probe (NP) density profiles. ASIRAS-NP-derived accumulation rates are not statistically different (95 % confidence interval) from in situ EGIG accumulation measurements from 1985 to 2004. ASIRAS-NP-derived accumulation increases by 20 % below 3000 m elevation, and increases by 13 % above 3000 m elevation for the period 1995 to 2004 compared to 1985 to 1994. Three Regional Climate Models (PolarMM5, RACMO2.3, MAR) underestimate snow accumulation below 3000 m by 16–20 % compared to ASIRAS-NP from 1985 to 2004. We test radar-derived accumulation rates sensitivity to density using modeled density profiles in place of NP densities. ASIRAS radar layers combined with Herron and Langway (1980) model density profiles (ASIRAS-HL) produce accumulation rates within 3.5 % of ASIRAS-NP estimates in the dry snow region. We suggest using Herron and Langway (1980) density profiles to calibrate radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements, such as those observed by the Operation IceBridge campaign.

Optimization of the SiC Powder Source Size Distribution for the Sublimation Growth of Long Crystals Boules

2019 ◽  
Vol 963 ◽  
pp. 42-45
Author(s):  
Johannes Steiner ◽  
Matthias Arzig ◽  
Ta Ching Hsiao ◽  
Peter J. Wellmann
Keyword(s):  
Size Distribution ◽  
Shape Change ◽  
Growth Conditions ◽  
Powder Size ◽  
Growth Interface ◽  
Morphology Change ◽  
Powder Density ◽  
Stable Growth ◽  
Sublimation Growth

The influence of four different SiC source powder size distributions on the sublimation behavior during physical vapor transport growth of SiC was studied. The growth processes were carried out in a 3 inch crystal growth setup and observed in situ using advanced 3D computed tomography X-ray visualization. The single modal D90 size distribution of two source powders was 50 μm and 200 μm, respectively, with a corresponding average powder density of 1.17 g/cm3. The third source powder consisted of a blend of the previously named powders and exhibited an average powder density of 1.66 g/cm3 with a bimodal particle size distribution. The last source was composed of a solid polycrystalline SiC cylinder. The bimodal powder source exhibited a smoother morphology change and material consumption during the growth run and led to a much more stable shape change of the growth interface compared to the single modal source powders. The solid source featured the least morphology change. Therefore, with a careful adaption of the source material stable growth conditions can be achieved.

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