First measurements of an imaging heavy ion beam probe at the ASDEX Upgrade tokamak.

The imaging heavy ion beam probe (i-HIBP) diagnostic has been successfully commissioned at ASDEX Upgrade. The i-HIBP injects a primary neutral beam into the plasma, where it is ionized, leading to a fan of secondary (charged) beams. These are deflected by the magnetic field of the tokamak and collected by a scintillator detector, generating a strike-line light pattern that encodes information on the density, electrostatic potential, and magnetic field of the plasma edge. The first measurements have been made, demonstrating the proof-of-principle of this diagnostic technique. A primary beam of 85/87Rb has been used with energies ranging between 60 and 72 keV and extracted currents up to 1.5 mA. The first signals have been obtained in experiments covering a wide range of parameter spaces, with plasma currents (Ip) between 0.2 and 0.8 MA and on-axis toroidal magnetic field (Bt) between 1.9 and 2.7 T. Low densities appear to be critical for the performance of the diagnostic, as signals are typically observed only when the line integrated density is below 2.0-3.0 × 1019 m-2 in the central interferometer chord, depending on the plasma shape. The strike line moves as expected when Ip is ramped, indicating that current measurements are possible. Additionally, clear dynamics in the intensity of the strike line are often observed, which might be linked to changes in the edge profile structure. However, the signal-to-background ratio of the signals is hampered by stray light, and the image guide degradation is due to neutron irradiation. Finally, simulations have been carried out to investigate the sensitivity of the expected signals to plasma density and temperature. The results are in qualitative agreement with the experimental observations, suggesting that the diagnostic is almost insensitive to fluctuations in the temperature profile, while the signal level is highly determined by the density profile due to the beam attenuation.

Conceptual study for velocity space resolved thermal ion loss detection in tokamaks.

A new concept for velocity space thermal ion loss detection is presented. This diagnostic provides pitch angle resolved measurements that are unfeasible with current diagnostics. It uses the same detection principle as the Fast-Ion Loss Detector with a scintillator as the active component and includes a double slit configuration to measure simultaneously the escaping counter- and co-current ions. Simulations show a gyroradius range between 0.15 and 1.00 cm with a resolution below 0.15 cm (for a gyroradius of 1 cm) and a pitch angle range between 30° and 150° with a resolution below 8° for both counter- and co-current ions. The formation of a sheath in front of the detector and its associated electric field may impact the detection principle. Preliminary simulations with a homogeneous electric field show a decrease in the measurable velocity space range, whereas the gyroradius and pitch angle resolution barely change. The strike map is sensitive to the sheath electric field.

Design and simulation of an imaging neutral particle analyzer for the ASDEX Upgrade tokamak.

An Imaging Neutral Particle Analyzer (INPA) diagnostic has been designed for the ASDEX Upgrade (AUG) tokamak. The AUG INPA diagnostic will measure fast neutrals escaping the plasma after charge exchange reactions. The neutrals will be ionized by a 20 nm carbon foil and deflected toward a scintillator by the local magnetic field. The use of a neutral beam injector (NBI) as an active source of neutrals will provide radially resolved measurements, while the use of a scintillator as an active component will allow us to cover the whole plasma along the NBI line with unprecedented phase-space resolution (<12 keV and 8 cm) and a fast temporal response (up to 1 kHz with the high resolution acquisition system and above 100 kHz with the low resolution one), making it suitable to study localized fast-ion redistributions in phase space.

Implementation of synthetic fast-ion loss detector and imaging heavy ion beam probe diagnostics in the 3D hybrid kinetic-MHD code MEGA.

A synthetic fast-ion loss (FIL) detector and an imaging Heavy Ion Beam Probe (i-HIBP) have been implemented in the 3D hybrid kinetic-magnetohydrodynamic code MEGA. First synthetic measurements from these two diagnostics have been obtained for neutral beam injection-driven Alfvén Eigenmode (AE) simulated with MEGA. The synthetic FILs show a strong correlation with the AE amplitude. This correlation is observed in the phase-space, represented in coordinates (Pϕ, E), being toroidal canonical momentum and energy, respectively. FILs and the energy exchange diagrams of the confined population are connected with lines of constant E', a linear combination of E and Pϕ. First i-HIBP synthetic signals also have been computed for the simulated AE, showing displacements in the strike line of the order of ∼1 mm, above the expected resolution in the i-HIBP scintillator of ∼100 µm.

Variability in the primary emissions and secondary gas and particle formation from vehicles using bioethanol mixtures.

Bioethanol for use in vehicles is becoming a substantial part of global energy infrastructure because it is renewable and some emissions are reduced. Carbon monoxide (CO) emissions and total hydrocarbons (THC) are reduced, but there is still controversy regarding emissions of nitrogen oxides (NOx), aldehydes, and ethanol; this may be a concern because all these compounds are precursors of ozone and secondary organic aerosol (SOA). The amount of emissions depends on the ethanol content, but it also may depend on the engine quality and ethanol origin. Thus, a photochemical chamber was used to study secondary gas and aerosol formation from two flex-fueled vehicles using different ethanol blends in gasoline. One vehicle and the fuel used were made in the United States, and the others were made in Brazil. Primary emissions of THC, CO, carbon dioxide (CO2), and nonmethane hydrocarbons (NMHC) from both vehicles decreased as the amount of ethanol in gasoline increased. NOx emissions in the U.S. and Brazilian cars decreased with ethanol content. However, emissions of THC, CO, and NOx from the Brazilian car were markedly higher than those from the U.S. car, showing high variability between vehicle technologies. In the Brazilian car, formation of secondary nitrogen dioxide (NO2) and ozone (O3) was lower for higher ethanol content in the fuel. In the U.S. car, NO2 and O3 had a small increase. Secondary particle (particulate matter [PM]) formation in the chamber decreased for both vehicles as the fraction of ethanol in fuel increased, consistent with previous studies. Secondary to primary PM ratios for pure gasoline is 11, also consistent with previous studies. In addition, the time required to form secondary PM is longer for higher ethanol blends. These results indicate that using higher ethanol blends may have a positive impact on air quality. IMPLICATIONS: The use of bioethanol can significantly reduce petroleum use and greenhouse gas emissions worldwide. Given the extent of its use, it is important to understand its effect on urban pollution. There is a controversy on whether there is a reduction or increase in PM emission when using ethanol blends. Primary emissions of THC, CO, CO2, NOx, and NMHC for both cars decreased as the fraction of ethanol in gasoline increased. Using a photochemical chamber, the authors have found a decrease in the formation of secondary particles and the time required to form secondary PM is longer when using higher ethanol blends.

Particle size distribution and its relationship to black carbon in two urban and one rural site in Santiago de Chile.

The size distribution of particles has been studied in three sites in the Metropolitan area of Santiago de Chile in the winter of 2009 and a comparison with black carbon was performed. Two sites are located near busy streets in Santiago and the other site is located in a rural area about 40 km west of Santiago with little influence from vehicles, but large influence from wood burning. The campaign lasted 1 or 2 weeks in each site. We have divided the particle size measurements into four groups (10-39 nm, 40-62 nm, 63-174 nm, and 175-700 nm) in order to compare with the carbon monitor. In the sites near the street, black carbon has a high correlation (R = 0.85) with larger particles (175-700 nm). The correlation decreased when black carbon was compared with smaller particles, having very small correlation with the smallest sizes (10-39 nm). In the rural site, black carbon also has a high correlation (R = 0.86) with larger particles (175-700 nm), but the correlation between black carbon and the finest particles (10-39 nm) decreases to near 0. These measurements are an indication that wood burning does not generate particles smaller than -50 nm. In the urban sites, particle size distribution is peaked toward smaller particles (10-39 nm) only during rush hours, but at other times, particles size distribution is peaked toward larger sizes. When solar radiation was high, evidence of secondary particle formation was seen in the rural site, but not in the urban sites. The correlation between the number of secondary particles and solar radiation was R2 = 0.46, indicating that it there may be other variables that play a role in ultrafine particle formation. Implications: A study of the size distribution of particles and black carbon concentration in two street sites and one rural site shows that in the last site the number of particles ultrafine particles (d < 40 nm) is 10 times lower but the number of larger particles is about 2 times lower. Thus, the rural site has less of the particles that are more dangerous to health. The number ofultrafine particles is mostly associated with traffic, while the number of larger particles is associated with wood burning and other sources. Wood burning does not generate particles smaller than -50 nm.

Evaluation of thermal simulation of households in the metropolitan region of São Paulo, Brazil.

This paper aims at assessing the performance of a program of thermal simulation (Arquitrop) in different households in the city of Sao Paulo, Brazil. The households were selected for the Wheezing Project which followed up children under 2 years old to monitor the occurrence of respiratory diseases. The results show that in all three study households there is a good approximation between the observed and the simulated indoor temperatures. It was also observed a fairly consistent and realistic behavior between the simulated indoor and the outdoor temperatures, describing the Arquitrop model as an efficient estimator and good representative of the thermal behavior of households in the city of Sao Paulo. The worst simulation is linked to the poorest type of construction. This may be explained by the bad quality of the construction, which the Architrop could not simulate adequately.

Source apportionment of urban particulate aliphatic and polynuclear aromatic hydrocarbons (PAHs) using multivariate methods.

Samples of organic aerosol were collected in Santiago de Chile. An activated-charcoal diffusion denuder was used to strip out organic vapors prior to particle collection. Both polynuclear aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons were determined using gas chromatography/mass spectrometry (GC/MS). Organic particle sources were resolved using both concentration diagnostic ratios and multivariate methods such as hierarchical cluster analysis (HCA) and factor analysis (FA). Four factors were identified based on the loadings of PAHs and n-alkanes and were attributed to the following sources: (1) high-temperature combustion of fuels; (2) fugitive emissions from oil residues; (3) biogenic sources; and (4) unburned fuels. Multilinear regression (MLR) analysis was used to determine emission profiles and contributions of the sources. The reconstructed concentrations of particle phase aliphatic and polynuclear aromatic hydrocarbons were in good agreement (R2 > 0.70) with those measured in Santiago de Chile.

Source apportionment of PM10 and PM2.5 in five Chilean cities using factor analysis.

Chile is a fast-growing country with important industrial activities near urban areas. In this study, the mass and elemental concentrations of PM10 and PM2.5 were measured in five major Chilean urban areas. Samples of particles with diameter less than 10 microm (PM10) and 2.5 microm (PM2.5) were collected in 1998 in Iquique (northern Chile), Valparaiso, Viña del Mar, Rancagua (central Chile), and Temuco (southern Chile). Both PM10 and PM2.5 annual mean concentrations (PM10: 56.9-77.6 microg/m3; PM2.5: 22.4-42.6 microg/m3) were significantly higher than the corresponding European Union (EU) and U.S. Environmental Protection Agency (EPA) air quality standards. Moreover, the 24-hr PM10 and PM2.5 U.S. standards were exceeded infrequently for some of the cities (Rancagua and Valparaiso). Elements ranging from Mg to Pb were detected in the aerosol samples using X-ray fluorescence (XRF). For each of the five cities, factor analysis (FA) was applied to identify and quantify the sources of PM10 and PM2.5. The agreement between calculated and measured mass and elemental concentrations was excellent in most of the cities. Both natural and anthropogenic sources were resolved for all five cities. Soil and sea were the most important contributors to coarse particles (PM10-PM2.5), whereas their contributions to PM2.5 were negligible. Emissions from Cu smelters and oil refineries (and/or diesel combustion) were identified as important sources of PM2.5, particularly in the industrial cities of Rancagua, Valparaiso, and Viña del Mar. Finally, motor vehicles and wood burning were significant sources of both PM2.5 and PM10 in most of the cities (wood burning was not identified in Iquique).