Photoionization in gases and photoelectric emission from solids

Weissler, G. L.

doi:10.1007/978-3-642-45844-6_4

Cited by 33 publications

(22 citation statements)

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“…If, on the other hand, the surface were coated with ice or water, whose photoelectric work function is 6.1 V [Von Engel, 1965], the relevant solar flux would be of wavelength less than 2000 A The yield curves for all high-workfunction materials when plotted as a function of the wavelength in a semilogarithmic graph are simply displaced from one another, retaining almost similar shapes for several electron volts above the workfunction value [Von Engel, 1965]. This feature also appears to have some theoretical validity [Weissler, 1956]. In the absence of a yield curve for ice or water in the published literature, we estimated the yield fgr these materials on the above basis as 10-6 at 2000 A, IQ-5 at 1750 A and 10-3 at the Lyman-alpha wavelength of 1216 X.…”

Section: Discussion Of Resultsmentioning

confidence: 93%

Effect of Meteoric Dust on the Effective Recombination Coefficient in the Lower Ionosphere

Parthasarathy

1966

Radio Science

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The effect of meteoric dust particles on the steady-state distribution of electrons and ious in the lower ionosphere (SQ-90 km) has been investigated. A formal expression for the effective recombination coefficient has also been derived, containing the terms for the rates of capture of electrons and positive and negative ions by the dust. These capture rates are derived by an extension of Natanson's theory of aerosol charging by the capture of ions. The altitude dependence of these coefficients is mainly determined by the altitude distribution of the dust concentration. It is found that only particles with radii larger than about a tenth of a micron play a significant role.The numerical values of the effective recombination coefficient for several altitudes in the D region have been compared with the values empirically determined by us from multiple-frequency radiowave absorption data in the auroral zone, and found to be in satisfactory argeement. It is also .shown that the role of dust-concentration in the D region is of major significance when the ionization density is weak to moderate. For a strongly ionized D region, the role is significant only if the dust concentration is higher than is currently believed probable.

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Section: Discussion Of Resultsmentioning

confidence: 93%

Effect of Meteoric Dust on the Effective Recombination Coefficient in the Lower Ionosphere

Parthasarathy

1966

Radio Science

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“…Second, high energy photons are readily absorbed in gas at atmospheric pressure [7]. Lower energy photons are more numerous and are not as readily absorbed, but do not have the energy to ionize a gas neutral directly.…”

Section: Description Of Effect Of Dielectric Photoemissionmentioning

confidence: 99%

Effect of Dielectric Photoemission on Surface Breakdown: An LDRD Report

Jorgenson¹,

Warne²,

Neuber³

et al. 2003

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The research discussed in this report was conceived during our earlier attempts to simulate breakdown across a dielectric surface using a Monte Carlo approach. While cataloguing the various ways that a dielectric surface could affect the breakdown process, we found that one obvious effect -photoemission from the surface -had been ignored. Initially, we felt that inclusion of this effect could have a major impact on how an ionization front propagates across a surface because of the following argument chain: (1) The photon energy required to release electrons from a surface via photoemission is less than the photon energy required to ionize gas molecules directly. (2) The mean free path of a photon in gas is longer for low-energy photons than for high-energy photons. (3) Photoionization is a major effect in advancing the ionization front for breakdown in gas without a surface, therefore, we know that even high-energy photons can be released from the head of a streamer and propagate some distance through the gas. Our hypothesis, therefore, was that photons with energies near the threshold of photoemission could travel further in front of the streamer before being absorbed than higher-energy photons needed for photoionization, yet the lower-energy photons, with the help of the surface, could still create seed electrons for new avalanches. Thus, the streamer would advance more rapidly next to a surface than in gas alone. Additionally, the photoemission from the surface would add to the electrons in the avalanche and cause the avalanche to grow faster. After some study, however, we are forced to conclude that although photoemission does contribute to avalanche growth at fields near breakdown threshold, secondary electron emission causes electrons to stick to the surface and cancels out the growth due to photoemission. This conclusion assumes a discharge that occurs over a short period of time so that charging of the surface, which could alter its secondary electron emission characteristics, does not occur. This report documents the numerical work we did on investigating this effect and the experimental work we did on pre-breakdown phenomena in gas.

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“…A later review by Weissler (1956) is in a similar vein, but Is more extensive, and covers experimental studies of photoelectrir-effect phenomena as well as theoretical investigations.…”

Section: \Vmentioning

confidence: 98%

“…Table 8-2 Implortant References on Photoelectric Absorption Cross Sections Kramers (1923) Milne (1924) Olppnhelmr (1928 Gaunt (1930) Stobbe (1930) Maue (1932) Monxel and Pekeris (1935) Massey and Smith (1936) Hall (1936) 8ommerfeld (1939) Bates, Buckingham, Massey and Unwln (1939) Bates and Massey (1943) Bates (1946a, b) Dates and Seaton (1949) Seaton (1951) Weissler (1956 Bathe and Salpeter (1957) Seaton (1958) Kelly and Armstrong (1959) Armstrong and Kelly (1959) Armstrong (1959, 1964b) Burgess and Seaton (1960) Dalgarno and Parkinson (1960) Karzas and Latter (1961) Cooper and Martin (1962) Cooper (1962) Dalgarno, Henry, and Stewart (1964) Johnston (1964) Burgess (1964 Wheeler and Wildt (1942) Chandrasekhar and Breen (1946) Mayer (1947) Berger (1956) Bethe and Salpeter (1957) Grant (1958) Karzas and Latter (1961) Rre-ne, Jr., and Nardone (1960,1961,1963) Brussaard and Van de Hulst (1962) Peach (19F5) 8.2…”

Section: L45 3h5mentioning

confidence: 99%

Thermal Radiation Phenomena. Volume Ii. The Equilibrium Radiative Properties of Air - Theory

Armstrong¹,

Nicholls²

1967

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INTRODUCTIONThis volume is one of a set which is concerned with all aspects of thermal radiation phenomena in heated air, over a wide range of temperature and density. Thermal radiation phenomena are meant to be those which arise due to or are related to, the passage of electromagnetic energy through an atmosphere of some type when significant interaction occurs between the radiation stream and the atmosphere. It is usually implied that some type of partial thermal equilibrium is produced by this interaction, although not a complete one, of course. In the case of complete thermal equilibrium, there can be only an uninteresting homogeneous system with no net transport of radiation at all. Radiation is a significant mode of energy transfer in all gases at sufficiently high temperatures, and in many situations at low temperatures as well. Since radiative energy transfer is controlled by the absorption coefficient which is, in turn determined by the microscopic atomic and molecular, and the statistical/thermodynamic properties of the medium, much of these volumes are concerned with these underlying properties. In particular, after a brief introduction to the theory of radiative transfer limited to conditions of local thermodynamic equilibrium, the present volume is mainly concerned with the detailed application of the basic quantum theory of radiation to real atomic and molecular systems. The transfer problem only reappears occasionally to guide this application into the practical channels which constitute the raison d'etre of the book.Although radiation transport is now of wide interdisciplinary application, most of its basic developments were made in an astrophysical milieu. Some of its contemporary applications are in stellar, solar and planetary atmospheres and aeronomy, in meteor, missile and rocket re-entry phenomena, in F combustion physics and chemistry, and in plasma and weapons physics.Towards very high temperatures there are fewer contributing effects and therefore the situation is conceptually somewhat simpler. Fig. 1.1 illustrates some significant subdivisions and interrelations towards the high-temperature limit of our considerations. As one progresses downwards in temperature, the effects and interactions proliferate and become, at our present state of knowledge, more fragmented and diverse, so that we will not attempt an illustration in this case,A large fraction of the work dating from World War II on specific problems in the above fields of application has been motivated by defense needs and financed by government contracts. As a result, much of the literature on the subject is comprised of unpublished and therefore unrefereed contract reports which are not universally available to the scientific community. Much of the work described in this "grey" literature (Goody, 1964) is important, but some obscurities and errors in an already complex field have propagated through these reports. Other problems due to the particular history of this field have also occurred. For example, a perusal of the reports...

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Photoionization in gases and photoelectric emission from solids

Cited by 33 publications

References 1 publication

Effect of Meteoric Dust on the Effective Recombination Coefficient in the Lower Ionosphere

Effect of Meteoric Dust on the Effective Recombination Coefficient in the Lower Ionosphere

Effect of Dielectric Photoemission on Surface Breakdown: An LDRD Report

Thermal Radiation Phenomena. Volume Ii. The Equilibrium Radiative Properties of Air - Theory

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