Microwave method of investigating the afterglows of pulsed gaseous discharges

Sexton, M. C.; Lennon, J J; Mulcahy, M. J.

doi:10.1088/0508-3443/10/8/304

Cited by 9 publications

(4 citation statements)

References 7 publications

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“…The experimental rates vary with pressure to the 1.7 power, compared with a power of 2 for attachment, and the experimental rates are about a factor of 40 slower than attachment. This is similar to the early observations for plasmas generated by microwave breakdowns, as described in P 1; in fact, the present rates are consistent with the early breakdown results in [4] as shown in figure 11. The number of different reactions that could be responsible for these more complex conductivity decays is large enough that a detailed kinetic model will be required to interpret the results.…”

Section: Synthetic Airsupporting

confidence: 92%

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Afterglow conductivity measurements of air and N₂following intense electron-beam excitation

Spencer

Dickinson

Eckstrom

1987

J. Phys. D: Appl. Phys.

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We have developed a new method of applying the microwave cavity perturbation technique that allows us to measure simultaneously real and imaginary conductivity decays. We report here results of afterglow decay measurements for air and N2 excited by an intense e-beam pulse. From these data, we calculate electron densities arid electron temperatures using exact expressions for the conductivities. The electron density decays for laboratory and synthetic air are approximately 10 and 40 times longer than predicted based on electron attachment for humid and dry air, respectively. Ambipolar diffusion coefficients and dissociative recombination rates measured at low pressures are inconsistent with previous results because our deduced electron temperatures are much higher than values used in previous studies. The decays in humid air appear to be dominated by ion conductivity.

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Section: Synthetic Airsupporting

confidence: 92%

“…Examination of equations ( 2) or (4) shows that the conductivity varies inversely with the mass of the charge carrier. Then the ion concentration would have to be comparable to the electron concentration times the ratio milme = Mi X 1860, where Mi is the molecular weight of the ion.…”

Section: Microwave Cavity Perturbation Techniquementioning

confidence: 99%

Afterglow conductivity measurements of air and N₂following intense electron-beam excitation

Spencer

Dickinson

Eckstrom

1987

J. Phys. D: Appl. Phys.

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“…The measurements may be made (a) during the decay of electron density following a period of irradiation by a pulsed source (20)(21)(22)(23)(24)(25)(26)(27), (b) during irradiation of the gas by a steady state source (20,28,39), or (c) during the decay of density following a pulsed discharge (30)(31)(32)(33)(34)(35)(36)(37)(38). A variant of these studies is to use Langmuir probes to measure the time variation of the electron density (21).…”

Section: (B) High Frequency Studiesmentioning

confidence: 99%

“…A source of error in these experiments is the presence of excited species which may cause detachment and a reduction in the apparent attachment rate (12,43,44). This problem is most serious when the electrons are produced by an electrical discharge (30)(31)(32)(33)(34)(35)(36)(37)(38), i.e., when the fraction of the electrons with sufficient energy to ionize the gas is small compared to the fraction which can produce excited and dissociated molecules (8,10). Until the effects of excited species, etc.…”

Section: (B) High Frequency Studiesmentioning

confidence: 99%

Laboratory studies of electron attachment and detachment processes of aeronomic interest

Phelps¹

1969

Can. J. Chem.

116

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Techniques for the study of electron attachment and detachment are reviewed. The rate coefficients for the various processes of aeronomic interest are then discussed. The rates of three-body and dissociative attachment by thermal electrons have been successfully determined by swarm techniques and by high frequency studies of electrons produced by high energy particles and by photoionization. Collisional and associative detachment rates for thermal energy negative ions have been measured using the swarm and flowing afterglow techniques. Radiative attachment rates for some atmospheric negative ions have been calculated from measurements of photodetachment cross sections using crossed photon and ion beam techniques. Electron beam studies and measurements of ion kinetic energy have provided much useful information regarding the dissociative attachment process and the structure of molecular negative ions. Rate coefficients for low energy processes such as the three-body attachment to O,, the radiative attachment to 0 , and the associative detachment of 0-in collisions with various atmospheric gases are reasonably well known. Other possibly important low energy processes, such as dissociative attachment to 0 3 , radiative attachment to O,, and the associative detachment of 02-areless well known.Canadian Journal of Chemistry, 47, 1783 (1969) Introduction Laboratory measurements of the rates of loss of free electrons by collisional attachment to molecular oxygen and radiative attachment to atomic oxygen under conditions of electron energy and gas temperature appropriate to the earth's atmosphere were first reported about 10 years ago. Measurements of photodetachment rates for 0-and 0,-were made at about the same time. Information concerning such processes as of 1963 were reviewed by Branscomb (1). Although progress has been made in refining and understanding these processes, it was not until 1966 that really significant new laboratory data in the area of electron attachment and detachment processes became available in the form of associative detachment coefficients for 0-and 0,-in collisions with atomic oxygen (2). These results, along with the accompanying studies of negative ion -molecule reaction rates ( 2 4 ) have made possible much more realistic models of the electron -negative ion balance at altitudes where atomic oxygen is present (3-5). In keeping with the purposes of this Symposium we will limit our discussion to some of the laboratory techniques and results which form a basis for atmospheric models.Electron attachment and detachment processes which are considered to be of aeronomic interest

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Electronic Recombination

Bates¹,

Dalgarno²

1962

Pure and Applied Physics

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Microwave method of investigating the afterglows of pulsed gaseous discharges

Cited by 9 publications

References 7 publications

Afterglow conductivity measurements of air and N₂following intense electron-beam excitation

Afterglow conductivity measurements of air and N₂following intense electron-beam excitation

Laboratory studies of electron attachment and detachment processes of aeronomic interest

Electronic Recombination

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Microwave method of investigating the afterglows of pulsed gaseous discharges

Cited by 9 publications

References 7 publications

Afterglow conductivity measurements of air and N2following intense electron-beam excitation

Afterglow conductivity measurements of air and N2following intense electron-beam excitation

Laboratory studies of electron attachment and detachment processes of aeronomic interest

Electronic Recombination

Contact Info

Product

Resources

About

Afterglow conductivity measurements of air and N₂following intense electron-beam excitation

Afterglow conductivity measurements of air and N₂following intense electron-beam excitation