Electron current to a cylindrical probe in a moving high pressure plasma

Dawe, J. R.; Rizvi, S. A. H.; Smy, P. R.

doi:10.1109/27.221123

Cited by 15 publications

(6 citation statements)

References 9 publications

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“…An explanation of this disagreement between ICSPA and PPA can be found in Franke et al 51 who observed that the weakness of the correspondence between ICSPA and PPA occurs in configurations that convert high gas flow in the vicinity of the spark plug electrode gap at ignition – to high turbulence regime in proximity of peak pressure, and considered this turbulence as reason of the weak agreement between ICSPA and PPA. Actually, in the IC measurement, the spark plug tip basically works as a Langmuir probe, as shown in Strandh et al 27 Thus the conclusion of Franke et al 51 is consistent with the observation of Dawe et al 56 who found that the electron current flowing in a positively biased cylindrical probe immersed in a moving plasma is influenced by flow velocity. This proves that IC signal variability cannot be attributed to noise, but to other variables that were not considered, such as local gas flow velocity.…”

Section: Discussionsupporting

confidence: 71%

Assessment of the reliability of ionization current measurement in estimating peak pressure angle in a spark ignition engine

Giglio¹,

Ragione²,

Gaeta³

et al. 2021

International Journal of Engine Research

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Ionization current measured at the spark plug during combustion in spark ignition engines has often been proposed to determine the crank-angle at combustion pressure peak, namely the peak pressure angle, for the purpose of regulating spark timing to attain maximum brake torque (MBT). The proposal is based on the assumption that agreement exists between peak pressure angle and the angular position of the ionization current second peak, although no one has ever proved it by an appropriate statistical analysis. The aim of this work, for the first time and by rigorous statistical methods, is to prove the agreement between Peak Pressure Angle and Ionization Current Second Peak Angle (ICSPA), without which a MBT control via ICSPA would be ineffective. Our experimental database consisted of about 9000 pairs of Peak Pressure Angle and Ionization Current Second Peak Angle values corresponding to 90 different operating conditions of a spark ignition engine. A two-sample comparison was first carried out between mean values of Peak Pressure Angle and Ionization Current Second Peak Angle, which showed a statistically significant difference between them. Then Bland-Altman analysis (Lancet, 1986), widely known and used for checking agreement between two different measurement methods, was conducted. It demonstrated that under almost all the experimental operating conditions, there was no agreement between the Ionization Current Second Peak Angle and the Peak Pressure Angle.

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Section: Discussionsupporting

confidence: 71%

Assessment of the reliability of ionization current measurement in estimating peak pressure angle in a spark ignition engine

Giglio¹,

Ragione²,

Gaeta³

et al. 2021

International Journal of Engine Research

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“…Since the flame is a quasineutral thermal plasma, the number concentration of positive ions must equal the number concentration of negative ions plus electrons (n + = n − + n e ) at any location in the flame [25,26]. On this basis we can readily calculate the number concentration of negative ions, which is of similar concentration with positive ions, due to the small concentration of electrons compared with that of positive ions as measured by the Langmuir double probe.…”

Section: Methodsmentioning

confidence: 98%

Method of measuring charge distribution of nanosized aerosols

Kim

Woo

Liu

et al. 2005

Journal of Colloid and Interface Science

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“…This region is rarely considered in the literature for the purpose of the electron temperature determination, although some work has been published in the frame of Orbital Motion Limit theories [87]. Also, in [80,81] this region is used because it provides high currents in their relatively low pressure (and low ionization) regimes.…”

Section: ) Electron and Ion Velocities Have A Maxwellian Distributionmentioning

confidence: 99%

“…To the author's knowledge, the works dealing with these high values are only Clements and Smy's paper of 1972 [113] and Holmes et al [105]. Also, Dawe et al [81], while stating the validity of the "sheath convection mode" (attributed to Smy [84] for regimes from 10 20 m -3 up to 10 29 m -3 (evidently a print error! ), limits his experimental analysis to flames similar to those discussed by Clements and Smy [79,91,111,114,115].…”

Section: Introductionmentioning

confidence: 98%

“…Up to relatively recent years, Langmuir probes have been limited to collisionless plasmas and to ion current collection, but in more recent years they have been successfully applied to the characterization of (i) "denser" (higher pressure) plasmas where the effect of collisions become dominant [72,73], and (ii) "higher" degree of ionization (non weakly-ionized plasmas) [74,75] or (iii) of systems in which the plasma flow must be considered [76][77][78], possibly considering the cooling effects on the measured parameters [77,79]. Also, the extension to the collection of electronic currents has been developed in the last decade [80], [81].…”

Section: Introductionmentioning

confidence: 99%

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A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas

Fanara

Richardson

2001

J. Phys. D: Appl. Phys.

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The 'high-pressure' atmospheric (TIG) arc plasma is studied by means of a multi-Langmuir probe system. In order to determine the appropriate regime of operation, definitions of the plasma parameters for the description of the argon arc are considered and evaluations are presented. A description of the probe basic techniques is followed by an in-depth discussion of the different regimes of probe operation. The emphasis is put on atmospheric and flowing (arc) regimes. Probe sheath theories are compared and "Nonidealities" like cooling due to plasma-probe motion and probe emission mechanisms are then described.The extensive literature review reveals that the existing probe theories are inappropriate for a use in the TIG arc, because of 'high' pressure (atmospheric), broad range of ionization across the arc, flowing conditions, and ultimately, to the uncertainty about onset of Local Thermodynamical Equilibrium. The Langmuir probe system is built to operate in floating and biased conditions. The present work represents the first extensive investigation of electrostatic probes in arcs where the experimental difficulties and the primary observed quantities are presented in great detail. Analysis methodologies are introduced and experimental results are presented towards a unified picture of the resulting arc structure by comparison with data from emission spectroscopy. Results from different measurements are presented and comparison is made with data on TIG arcs present in literature. Probe obtained temperatures are lower than the values obtained from emission spectroscopy and this 'cooling' is attributed to electron-ion recombination. However, it is believed that probes can access temperatures regions not attainable by emission spectroscopy. Only axial electric potential and electric field are obtained because of the equipotential-probe requirement. Estimations of the sheath voltage and extension are obtained and a qualitative picture of the ion and electron current densities within the arc is given.on floating and plasma potentials and estimates of the sheath voltage are made, which are then compared with the results of Chapter 4. Chapter 13 deals with further 'electrical' parameters (current densities, electric field and electrical conductivity). In Chapter 14 several experimental results are presented together in order to gain a unified picture of the resulting arc structure and some observations about possible conduction structures within arcs are made. Finally Chapter 15, after a summary of the whole work, reports the conclusions obtained and suggests further investigations.

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Electron current to a cylindrical probe in a moving high pressure plasma

Cited by 15 publications

References 9 publications

Assessment of the reliability of ionization current measurement in estimating peak pressure angle in a spark ignition engine

Assessment of the reliability of ionization current measurement in estimating peak pressure angle in a spark ignition engine

Method of measuring charge distribution of nanosized aerosols

A Langmuir multi-probe system for the characterization of atmospheric pressure arc plasmas

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