The effects of applying electric fields on the mass spectrometric sampling of positive and negative ions from a flame at atmospheric pressure
Flames are plasmas, because they contain free electrons and both positive and negative ions. The concentrations of ions in a flat flame, burning at 1bar, have been measured by continuously sampling the hot (2400K) gas into a mass spectrometer at low pressure. The voltage, Δϕ, between the metallic bu...
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| Veröffentlicht in: | Combustion and flame 2014-12, Vol.161 (12), p.3249-3262 |
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| creator | Hayhurst, Allan N. Goodings, John M. Taylor, Stephen G. |
| description | Flames are plasmas, because they contain free electrons and both positive and negative ions. The concentrations of ions in a flat flame, burning at 1bar, have been measured by continuously sampling the hot (2400K) gas into a mass spectrometer at low pressure. The voltage, Δϕ, between the metallic burner and the plate holding the metallic sampling nozzle was varied; also, the flame was seeded with an alkali metal and doped with much larger quantities (mole fraction ⩽1.7%) of chlorine. Currents of ions such as K+ and Cl− were measured with the mass spectrometer for different Δϕ and indicated that the sampling nozzle repels free electrons, when it is at a negative potential with respect to the burner (Δϕ |
| doi_str_mv | 10.1016/j.combustflame.2014.06.012 |
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The concentrations of ions in a flat flame, burning at 1bar, have been measured by continuously sampling the hot (2400K) gas into a mass spectrometer at low pressure. The voltage, Δϕ, between the metallic burner and the plate holding the metallic sampling nozzle was varied; also, the flame was seeded with an alkali metal and doped with much larger quantities (mole fraction ⩽1.7%) of chlorine. Currents of ions such as K+ and Cl− were measured with the mass spectrometer for different Δϕ and indicated that the sampling nozzle repels free electrons, when it is at a negative potential with respect to the burner (Δϕ<0); consequently the nozzle is then covered by a cathodic sheath of positive ions. Likewise, when Δϕ≫0, the inlet orifice is covered by charged species from the plasma, forming an anodic sheath, from which some electrons reach the nozzle; also some positive and negative ions follow them and so leave the sample. Because the sampled gas is accelerated to a Mach number of unity on entering the inlet orifice, some ions have enough momentum to pass through both a sheath and the entrance hole into the mass spectrometer. The measurements enabled the non-uniform, electric potential between the burner and the plate housing the sampling nozzle to be sketched. The thicknesses of the sheaths were also measured; a cathodic sheath of positive ions is much thicker than an anodic plasma sheath. Also, for Δϕ between zero and ∼+30V, the sheath around the inlet orifice is at its thinnest and the current detected for positive ions a maximum. This is when quantitative measurements of concentrations should be made for positive or negative ions. This study reveals the importance of the electron concentration, the diameter of the inlet orifice, the presence of a halogen, and Δϕ, for determining the thicknesses of these sheaths, which do affect the sampling of ions. With chlorine in the flame, the equilibrium: H+C1−=e−+HC1 is sufficiently fast to be maintained, whilst the sampled gas passes through the inlet orifice. This equilibrium usually freezes at some point during the sample’s subsequent, supersonic expansion into the first vacuum chamber; freezing temperatures were deduced. Also the additional cooling of a sample by heat transfer to the sampling nozzle was estimated. It can be difficult to measure accurately the concentration of a negative ion in a flame, because negative ions, unlike positive ones, are often lost during sampling by participating with free electrons in such a chemical equilibrium, which shifts while the sample is cooled.</description><identifier>ISSN: 0010-2180</identifier><identifier>EISSN: 1556-2921</identifier><identifier>DOI: 10.1016/j.combustflame.2014.06.012</identifier><identifier>CODEN: CBFMAO</identifier><language>eng</language><publisher>Amsterdam: Elsevier Inc</publisher><subject>Applied sciences ; Combustion. Flame ; Electric fields ; Energy ; Energy. Thermal use of fuels ; Exact sciences and technology ; Free electrons ; Inlets ; Ionisation ; Mass spectrometers ; Mass spectrometry ; Miscellaneous ; Negative ions ; Nozzles ; Positive and negative ions ; Positive ions ; Sampling ; Sampling a flame ; Sheaths ; Theoretical studies. Data and constants. Metering</subject><ispartof>Combustion and flame, 2014-12, Vol.161 (12), p.3249-3262</ispartof><rights>2014 The Combustion Institute.</rights><rights>2015 INIST-CNRS</rights><lds50>peer_reviewed</lds50><woscitedreferencessubscribed>false</woscitedreferencessubscribed><citedby>FETCH-LOGICAL-c420t-a280dbd11851ee0045b08138be245ff8028e604f79dc82a7c8e6164b2d10b2bc3</citedby><cites>FETCH-LOGICAL-c420t-a280dbd11851ee0045b08138be245ff8028e604f79dc82a7c8e6164b2d10b2bc3</cites></display><links><openurl>$$Topenurl_article</openurl><openurlfulltext>$$Topenurlfull_article</openurlfulltext><thumbnail>$$Tsyndetics_thumb_exl</thumbnail><linktohtml>$$Uhttps://dx.doi.org/10.1016/j.combustflame.2014.06.012$$EHTML$$P50$$Gelsevier$$H</linktohtml><link.rule.ids>314,780,784,3550,27924,27925,45995</link.rule.ids><backlink>$$Uhttp://pascal-francis.inist.fr/vibad/index.php?action=getRecordDetail&idt=28943527$$DView record in Pascal Francis$$Hfree_for_read</backlink></links><search><creatorcontrib>Hayhurst, Allan N.</creatorcontrib><creatorcontrib>Goodings, John M.</creatorcontrib><creatorcontrib>Taylor, Stephen G.</creatorcontrib><title>The effects of applying electric fields on the mass spectrometric sampling of positive and negative ions from a flame at atmospheric pressure</title><title>Combustion and flame</title><description>Flames are plasmas, because they contain free electrons and both positive and negative ions. The concentrations of ions in a flat flame, burning at 1bar, have been measured by continuously sampling the hot (2400K) gas into a mass spectrometer at low pressure. The voltage, Δϕ, between the metallic burner and the plate holding the metallic sampling nozzle was varied; also, the flame was seeded with an alkali metal and doped with much larger quantities (mole fraction ⩽1.7%) of chlorine. Currents of ions such as K+ and Cl− were measured with the mass spectrometer for different Δϕ and indicated that the sampling nozzle repels free electrons, when it is at a negative potential with respect to the burner (Δϕ<0); consequently the nozzle is then covered by a cathodic sheath of positive ions. Likewise, when Δϕ≫0, the inlet orifice is covered by charged species from the plasma, forming an anodic sheath, from which some electrons reach the nozzle; also some positive and negative ions follow them and so leave the sample. Because the sampled gas is accelerated to a Mach number of unity on entering the inlet orifice, some ions have enough momentum to pass through both a sheath and the entrance hole into the mass spectrometer. The measurements enabled the non-uniform, electric potential between the burner and the plate housing the sampling nozzle to be sketched. The thicknesses of the sheaths were also measured; a cathodic sheath of positive ions is much thicker than an anodic plasma sheath. Also, for Δϕ between zero and ∼+30V, the sheath around the inlet orifice is at its thinnest and the current detected for positive ions a maximum. This is when quantitative measurements of concentrations should be made for positive or negative ions. This study reveals the importance of the electron concentration, the diameter of the inlet orifice, the presence of a halogen, and Δϕ, for determining the thicknesses of these sheaths, which do affect the sampling of ions. With chlorine in the flame, the equilibrium: H+C1−=e−+HC1 is sufficiently fast to be maintained, whilst the sampled gas passes through the inlet orifice. This equilibrium usually freezes at some point during the sample’s subsequent, supersonic expansion into the first vacuum chamber; freezing temperatures were deduced. Also the additional cooling of a sample by heat transfer to the sampling nozzle was estimated. It can be difficult to measure accurately the concentration of a negative ion in a flame, because negative ions, unlike positive ones, are often lost during sampling by participating with free electrons in such a chemical equilibrium, which shifts while the sample is cooled.</description><subject>Applied sciences</subject><subject>Combustion. Flame</subject><subject>Electric fields</subject><subject>Energy</subject><subject>Energy. Thermal use of fuels</subject><subject>Exact sciences and technology</subject><subject>Free electrons</subject><subject>Inlets</subject><subject>Ionisation</subject><subject>Mass spectrometers</subject><subject>Mass spectrometry</subject><subject>Miscellaneous</subject><subject>Negative ions</subject><subject>Nozzles</subject><subject>Positive and negative ions</subject><subject>Positive ions</subject><subject>Sampling</subject><subject>Sampling a flame</subject><subject>Sheaths</subject><subject>Theoretical studies. Data and constants. Metering</subject><issn>0010-2180</issn><issn>1556-2921</issn><fulltext>true</fulltext><rsrctype>article</rsrctype><creationdate>2014</creationdate><recordtype>article</recordtype><recordid>eNqNkd1q3DAQhU1pods07yAKhd7YmZF_Vtu7kqZNIdCb5FrI8ijRYluqxhvIQ_SdK--G0MuAQIzmO2cknaL4hFAhYHexr2yY-gMvbjQTVRKwqaCrAOWbYoNt25VyJ_FtsQFAKCUqeF98YN4DwLap603x9_aBBDlHdmERnDAxjk9-vhc05qPkrXCexiH3ZrFkdDLMguPaCxMdATZTHFdJlsfAfvGPJMw8iJnuzbHwYWbhskAYcbyoMEteU-D4QKtFTMR8SPSxeOfMyHT-vJ8Vdz-ubi-vy5vfP39dfrspbSNhKY1UMPQDomqRCKBpe1BYq55k0zqnQCrqoHHb3WCVNFubS-yaXg4IvextfVZ8OfnGFP4ciBc9ebY0jmamcGCNXYv1DiU0Gf16Qm0KzImcjslPJj1pBL1moPf6_wz0moGGTucMsvjz8xzD1owumdl6fnGQatfUrdxm7vuJo_zoR09Js_U0Wxp8yl-th-BfM-4foICmrg</recordid><startdate>20141201</startdate><enddate>20141201</enddate><creator>Hayhurst, Allan N.</creator><creator>Goodings, John M.</creator><creator>Taylor, Stephen G.</creator><general>Elsevier Inc</general><general>Elsevier</general><scope>IQODW</scope><scope>AAYXX</scope><scope>CITATION</scope><scope>7TB</scope><scope>8FD</scope><scope>FR3</scope><scope>H8D</scope><scope>L7M</scope></search><sort><creationdate>20141201</creationdate><title>The effects of applying electric fields on the mass spectrometric sampling of positive and negative ions from a flame at atmospheric pressure</title><author>Hayhurst, Allan N. ; Goodings, John M. ; Taylor, Stephen G.</author></sort><facets><frbrtype>5</frbrtype><frbrgroupid>cdi_FETCH-LOGICAL-c420t-a280dbd11851ee0045b08138be245ff8028e604f79dc82a7c8e6164b2d10b2bc3</frbrgroupid><rsrctype>articles</rsrctype><prefilter>articles</prefilter><language>eng</language><creationdate>2014</creationdate><topic>Applied sciences</topic><topic>Combustion. Flame</topic><topic>Electric fields</topic><topic>Energy</topic><topic>Energy. Thermal use of fuels</topic><topic>Exact sciences and technology</topic><topic>Free electrons</topic><topic>Inlets</topic><topic>Ionisation</topic><topic>Mass spectrometers</topic><topic>Mass spectrometry</topic><topic>Miscellaneous</topic><topic>Negative ions</topic><topic>Nozzles</topic><topic>Positive and negative ions</topic><topic>Positive ions</topic><topic>Sampling</topic><topic>Sampling a flame</topic><topic>Sheaths</topic><topic>Theoretical studies. Data and constants. Metering</topic><toplevel>peer_reviewed</toplevel><toplevel>online_resources</toplevel><creatorcontrib>Hayhurst, Allan N.</creatorcontrib><creatorcontrib>Goodings, John M.</creatorcontrib><creatorcontrib>Taylor, Stephen G.</creatorcontrib><collection>Pascal-Francis</collection><collection>CrossRef</collection><collection>Mechanical & Transportation Engineering Abstracts</collection><collection>Technology Research Database</collection><collection>Engineering Research Database</collection><collection>Aerospace Database</collection><collection>Advanced Technologies Database with Aerospace</collection><jtitle>Combustion and flame</jtitle></facets><delivery><delcategory>Remote Search Resource</delcategory><fulltext>fulltext</fulltext></delivery><addata><au>Hayhurst, Allan N.</au><au>Goodings, John M.</au><au>Taylor, Stephen G.</au><format>journal</format><genre>article</genre><ristype>JOUR</ristype><atitle>The effects of applying electric fields on the mass spectrometric sampling of positive and negative ions from a flame at atmospheric pressure</atitle><jtitle>Combustion and flame</jtitle><date>2014-12-01</date><risdate>2014</risdate><volume>161</volume><issue>12</issue><spage>3249</spage><epage>3262</epage><pages>3249-3262</pages><issn>0010-2180</issn><eissn>1556-2921</eissn><coden>CBFMAO</coden><abstract>Flames are plasmas, because they contain free electrons and both positive and negative ions. The concentrations of ions in a flat flame, burning at 1bar, have been measured by continuously sampling the hot (2400K) gas into a mass spectrometer at low pressure. The voltage, Δϕ, between the metallic burner and the plate holding the metallic sampling nozzle was varied; also, the flame was seeded with an alkali metal and doped with much larger quantities (mole fraction ⩽1.7%) of chlorine. Currents of ions such as K+ and Cl− were measured with the mass spectrometer for different Δϕ and indicated that the sampling nozzle repels free electrons, when it is at a negative potential with respect to the burner (Δϕ<0); consequently the nozzle is then covered by a cathodic sheath of positive ions. Likewise, when Δϕ≫0, the inlet orifice is covered by charged species from the plasma, forming an anodic sheath, from which some electrons reach the nozzle; also some positive and negative ions follow them and so leave the sample. Because the sampled gas is accelerated to a Mach number of unity on entering the inlet orifice, some ions have enough momentum to pass through both a sheath and the entrance hole into the mass spectrometer. The measurements enabled the non-uniform, electric potential between the burner and the plate housing the sampling nozzle to be sketched. The thicknesses of the sheaths were also measured; a cathodic sheath of positive ions is much thicker than an anodic plasma sheath. Also, for Δϕ between zero and ∼+30V, the sheath around the inlet orifice is at its thinnest and the current detected for positive ions a maximum. This is when quantitative measurements of concentrations should be made for positive or negative ions. This study reveals the importance of the electron concentration, the diameter of the inlet orifice, the presence of a halogen, and Δϕ, for determining the thicknesses of these sheaths, which do affect the sampling of ions. With chlorine in the flame, the equilibrium: H+C1−=e−+HC1 is sufficiently fast to be maintained, whilst the sampled gas passes through the inlet orifice. This equilibrium usually freezes at some point during the sample’s subsequent, supersonic expansion into the first vacuum chamber; freezing temperatures were deduced. Also the additional cooling of a sample by heat transfer to the sampling nozzle was estimated. It can be difficult to measure accurately the concentration of a negative ion in a flame, because negative ions, unlike positive ones, are often lost during sampling by participating with free electrons in such a chemical equilibrium, which shifts while the sample is cooled.</abstract><cop>Amsterdam</cop><pub>Elsevier Inc</pub><doi>10.1016/j.combustflame.2014.06.012</doi><tpages>14</tpages></addata></record> |
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| subjects | Applied sciences Combustion. Flame Electric fields Energy Energy. Thermal use of fuels Exact sciences and technology Free electrons Inlets Ionisation Mass spectrometers Mass spectrometry Miscellaneous Negative ions Nozzles Positive and negative ions Positive ions Sampling Sampling a flame Sheaths Theoretical studies. Data and constants. Metering |
| title | The effects of applying electric fields on the mass spectrometric sampling of positive and negative ions from a flame at atmospheric pressure |
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