Pre-breakdown Ionization in Molecular Nitrogen in E x B Fields

Bagnall, FT; Haydon, S. C.

doi:10.1071/ph650227

Cited by 26 publications

(8 citation statements)

References 6 publications

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“…Experimental determinations of the swarm ionization rate divided by the neutral density in m 3 /s are displayed along with results from our simulations. Davies 83', Davies [1983]; Moruzzi 74', Moruzzi and Price [1974]; Raja Rao 71', Raja Rao and Govinda Raju [1971]; Harrison 53', Harrison and Geballe [1953]; Hays 87', Hays et al [1987]; Haydon '76, Haydon and Williams [1976]; Bagnall 65', Bagnall and Haydon [1965].…”

Section: Model Validationmentioning

confidence: 99%

Temporally self‐similar electron distribution functions in atmospheric breakdown: The thermal runaway regime

2010

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[1] Detailed Boltzmann kinetic calculations of the electron distribution functions resulting from thermal runaway in a constant electric field are presented. Thermal runaway is considered to occur when an initially thermal electron is accelerated above the 150 eV peak in the dynamical friction force in air and becomes a runaway electron. We investigate the role of runaway breakdown in situations where thermal runaway, as well as conventional breakdown, is occurring. The electric field strengths studied span the range from the threshold for runaway breakdown in air (∼0.3 MV/m at sea level) through conventional breakdown (2.4-3.2 MV/m at sea level) and exceeding the Dreicer field (25 MV/m at sea level), above which all electrons are runaways. We initiate our simulations with a population of pseudothermal electrons or with a combination of thermal and runaway (∼1 MeV) electrons. We find that when thermal runaway occurs the selfsimilar electron distribution function is identical in the presence or absence of a seed runaway population. We show that attempts to obtain the electric field from remote measurements of optical line ratios are ambiguous both in the context of the absolute field and in the underlying kinetics. By considering the runaway electrons as a separate population we conclude that the avalanche rate of low-energy electrons is equivalent to that of runaway electrons at a reduced field of 140 Td (3.8 MV/m at standard temperature and pressure). Above that field the conventional avalanche rate will control the avalanche rate of the entire population. Below that field the runaway avalanche rate will control the avalanche rate of the entire population.Citation: Colman, J. J., R. A. Roussel-Dupré, and L. Triplett (2010), Temporally self-similar electron distribution functions in atmospheric breakdown: The thermal runaway regime,

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Section: Model Validationmentioning

confidence: 99%

Temporally self‐similar electron distribution functions in atmospheric breakdown: The thermal runaway regime

2010

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“…The determinations of Maller and Naidu (1974) lie marginally above the present curve while the values of Jones (1968) fall well below all other results. The reason for this latter discrepancy is hard to determine and Haydon (1965); a, Folkard and Haydon (1973); A, Haydon and Williams (1976); e , Jones (1968); 0 , Maller and Naidu (1974); X , Kontoleon eta1 (1973).…”

Section: Resultsmentioning

confidence: 99%

“…A comparison of the present ~T / N data with previous measurements over the range 300 S E/N S 2400 Td in nitrogen is presented in figure 5 . Of all the previous work in nitrogen the most comprehensive study is that of the New England group (Bagnall and Haydon 1965, Folkard and Haydon 1973, Haydon and Williams 1973a, b, c, 1976. The present results show excellent agreement with these data.…”

Section: Resultsmentioning

confidence: 99%

“…Previous reports of experimental values of q'N (Bagnall and Haydon 1965, Jones 1968, Folkard and Haydon 1973, Maller and Naidu 1974, Haydon and Williams 1976 have not generally made the distinction between cui and at since the traditional steadystate experimental method used by these workers (with the exception of part of the work by Haydon and Williams) gives aT/N directly. The present integrated transient voltage method, however, yields the values of and DL separately.…”

Section: Introductionmentioning

confidence: 99%

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Transient voltage measurement of primary ionisation in nitrogen

Spriggs

Fletcher

1982

J. Phys. D: Appl. Phys.

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Electron impact ionisation of nitrogen gas has been studied using an integrated voltage method with the data subjected to a full analysis including the effects of diffusion. Values of the primary ionisation coefficient have been obtained over the swarm energy range 300 nTd<or=E/N<or=2400 Td. Experimental evidence has been obtained that secondary effects contribute greatly to the charge flow at these high values of E/N and that if not recognised may produce false values of alpha /N. The effect of ignoring diffusion at low gas pressures (p approximately=1 Torr) is also considered.

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“…These investigations support the validity of the equivalent pressure concept for hydrogen (Blevin and Haydon 1958) in which the mean free time T = Z/u ( I being the mean free path and U the average velocity of the electrons) was assumed to be substantially constant for hydrogen. An attempt was made (Bagnall and Haydon 1965) to extend this equivalent pressure concept to molecular nitrogen, in which the above condition of constant mean free path is not valid. A similar attempt is made (Bhiday et al 1967) to apply the equivalent pressure concept to atmospheric air.…”

Section: Introductionmentioning

confidence: 99%

Two-Wavelength Phase-Shifting Low-Coherence Digital Holography

Tamano

Otaka

Hayasaki

2008

jjap

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The measurements of the first ionization coefficient alp for air, without and with transverse magnetic fields, are reported in this paper. These were carried out using coaxial cylindrical electrodes to reduce the loss of electrons due to their drift in the E x H direction. The range of measurement covered the values of Elp between 200 and 600 V cm-1 torr-1 and those of H/p between 200 and 1400 G torr-1. The validity of the equivalent pressure concept was tested for the complicated medium like air. It has been shown that a satisfactory agreement between the theoretical and experimental values of alp, Hip and E/p was obtained for low values of Elp (< 300 V cm-1 torr-l) provided the collision frequency was taken to be an increasing function of Elp, instead of a constant as was assumed for hydrogen. At higher values of E/p (> 300), however, the observed values of alp, Hlp and'Elp were below those calculated on the basis of the equivalent pressure concept. A few measurements of ./p were also carried out using the pressure variation technique, and its operational utility has been established from the identical nature of the results.

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Pre-breakdown Ionization in Molecular Nitrogen in E x B Fields

Cited by 26 publications

References 6 publications

Temporally self‐similar electron distribution functions in atmospheric breakdown: The thermal runaway regime

Temporally self‐similar electron distribution functions in atmospheric breakdown: The thermal runaway regime

Transient voltage measurement of primary ionisation in nitrogen

Two-Wavelength Phase-Shifting Low-Coherence Digital Holography

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