Limits...
The effect of carrier gas contaminants on the charging probability of aerosols under bipolar charging conditions.

Steiner G, Reischl GP - J Aerosol Sci (2012)

Bottom Line: A recently developed high resolution mobility spectrometer allows the precise determination of the ions' electrical mobility; an empirical mass-mobility relationship was used to approximate the corresponding ion masses.Since the ion properties control the charging process of aerosols, it was further investigated how the different ion properties affect the calculation of the charging probabilities of aerosols.The results show that despite large variations of the ions' properties, only a minor effect on the calculated charging probabilities can be found.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Wien, Austria ; Department of Physics, University of Helsinki, P.O. Box 64, 00014, Finland.

ABSTRACT
This work concentrates on the experimental determination of the properties of ionic molecular clusters that are produced in the bipolar ionic atmosphere of a radioactivity based (241)Am charger. The main scope of this study was to investigate the dependency of the ions' properties on carrier gas contaminants caused by the evaporation of trace gases from different kinds of frequently encountered tubing materials. A recently developed high resolution mobility spectrometer allows the precise determination of the ions' electrical mobility; an empirical mass-mobility relationship was used to approximate the corresponding ion masses. It was found that impurities in the carrier gas dramatically change the pattern of the ion mobility/size distribution, resulting in very different ion properties that strongly depend on the carrier gas composition. Since the ion properties control the charging process of aerosols, it was further investigated how the different ion properties affect the calculation of the charging probabilities of aerosols. The results show that despite large variations of the ions' properties, only a minor effect on the calculated charging probabilities can be found.

No MeSH data available.


Related in: MedlinePlus

Experimental setup for the high resolution mobility measurements. Carefully, by means of two stages (ACF=Active Carbon Filter; HEPA=High Efficiency Particulate Airfilter), purified pressurized air is used as carrier gas for ions that are generated in the 241Am charger. These ions are subsequently analyzed according to their electrical mobility in a high resolution mobility analyzer called “UDMA” and detected by a Faraday Cup Electrometer (FCE). In the first set of experiments with clean and dry carrier gas conditions, only stainless steel or PTFE tubing and a short 10 cm PTFE tube between gas purification and charger was used. For additional experiments focusing on the influence of carrier gas contaminations, 2 m of different tubing material are inserted between the gas purification and the charger.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3473358&req=5

f0010: Experimental setup for the high resolution mobility measurements. Carefully, by means of two stages (ACF=Active Carbon Filter; HEPA=High Efficiency Particulate Airfilter), purified pressurized air is used as carrier gas for ions that are generated in the 241Am charger. These ions are subsequently analyzed according to their electrical mobility in a high resolution mobility analyzer called “UDMA” and detected by a Faraday Cup Electrometer (FCE). In the first set of experiments with clean and dry carrier gas conditions, only stainless steel or PTFE tubing and a short 10 cm PTFE tube between gas purification and charger was used. For additional experiments focusing on the influence of carrier gas contaminations, 2 m of different tubing material are inserted between the gas purification and the charger.

Mentions: Two experimental setups where in use during this study as schematically shown in Fig. 2: for the first one, the purified pressurized air is fed via a short connection tube made of PTFE of approximately 10 cm length to the 241Am charger which is mounted directly in front of the inlet of the high resolution UDMA. The ion clusters produced by the ionizing radiation immediately enter the UDMA for classification and are detected by a fast Faraday Cup Electrometer (FCEVIE-f), an updated version of the one described by Winklmayr et al. (1991), with a response time of typically 100 ms. For the first set of experiments, only air ducts of stainless steel or PTFE were in use. To ensure clean conditions for the whole system, the charger and air ducts as described above were flushed with the purified and dried air for a time period of 3 weeks—7 days a week and 24 h a day—before the start of the experiments. Only this way the influence of contaminants and trace gases led through the charger housing in the past can be reduced to a minimum.


The effect of carrier gas contaminants on the charging probability of aerosols under bipolar charging conditions.

Steiner G, Reischl GP - J Aerosol Sci (2012)

Experimental setup for the high resolution mobility measurements. Carefully, by means of two stages (ACF=Active Carbon Filter; HEPA=High Efficiency Particulate Airfilter), purified pressurized air is used as carrier gas for ions that are generated in the 241Am charger. These ions are subsequently analyzed according to their electrical mobility in a high resolution mobility analyzer called “UDMA” and detected by a Faraday Cup Electrometer (FCE). In the first set of experiments with clean and dry carrier gas conditions, only stainless steel or PTFE tubing and a short 10 cm PTFE tube between gas purification and charger was used. For additional experiments focusing on the influence of carrier gas contaminations, 2 m of different tubing material are inserted between the gas purification and the charger.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3473358&req=5

f0010: Experimental setup for the high resolution mobility measurements. Carefully, by means of two stages (ACF=Active Carbon Filter; HEPA=High Efficiency Particulate Airfilter), purified pressurized air is used as carrier gas for ions that are generated in the 241Am charger. These ions are subsequently analyzed according to their electrical mobility in a high resolution mobility analyzer called “UDMA” and detected by a Faraday Cup Electrometer (FCE). In the first set of experiments with clean and dry carrier gas conditions, only stainless steel or PTFE tubing and a short 10 cm PTFE tube between gas purification and charger was used. For additional experiments focusing on the influence of carrier gas contaminations, 2 m of different tubing material are inserted between the gas purification and the charger.
Mentions: Two experimental setups where in use during this study as schematically shown in Fig. 2: for the first one, the purified pressurized air is fed via a short connection tube made of PTFE of approximately 10 cm length to the 241Am charger which is mounted directly in front of the inlet of the high resolution UDMA. The ion clusters produced by the ionizing radiation immediately enter the UDMA for classification and are detected by a fast Faraday Cup Electrometer (FCEVIE-f), an updated version of the one described by Winklmayr et al. (1991), with a response time of typically 100 ms. For the first set of experiments, only air ducts of stainless steel or PTFE were in use. To ensure clean conditions for the whole system, the charger and air ducts as described above were flushed with the purified and dried air for a time period of 3 weeks—7 days a week and 24 h a day—before the start of the experiments. Only this way the influence of contaminants and trace gases led through the charger housing in the past can be reduced to a minimum.

Bottom Line: A recently developed high resolution mobility spectrometer allows the precise determination of the ions' electrical mobility; an empirical mass-mobility relationship was used to approximate the corresponding ion masses.Since the ion properties control the charging process of aerosols, it was further investigated how the different ion properties affect the calculation of the charging probabilities of aerosols.The results show that despite large variations of the ions' properties, only a minor effect on the calculated charging probabilities can be found.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Physics, University of Vienna, Boltzmanngasse 5, 1090 Wien, Austria ; Department of Physics, University of Helsinki, P.O. Box 64, 00014, Finland.

ABSTRACT
This work concentrates on the experimental determination of the properties of ionic molecular clusters that are produced in the bipolar ionic atmosphere of a radioactivity based (241)Am charger. The main scope of this study was to investigate the dependency of the ions' properties on carrier gas contaminants caused by the evaporation of trace gases from different kinds of frequently encountered tubing materials. A recently developed high resolution mobility spectrometer allows the precise determination of the ions' electrical mobility; an empirical mass-mobility relationship was used to approximate the corresponding ion masses. It was found that impurities in the carrier gas dramatically change the pattern of the ion mobility/size distribution, resulting in very different ion properties that strongly depend on the carrier gas composition. Since the ion properties control the charging process of aerosols, it was further investigated how the different ion properties affect the calculation of the charging probabilities of aerosols. The results show that despite large variations of the ions' properties, only a minor effect on the calculated charging probabilities can be found.

No MeSH data available.


Related in: MedlinePlus