Measurements of Secondary-Electron Spectra Produced by Electron Impact Ionization of a Number of Simple Gases

Opal, C. B.; Peterson, W. K.; Beaty, E. C.

doi:10.1063/1.1676707

Cited by 380 publications

(177 citation statements)

References 22 publications

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“…Neutral metal atoms in a hydrogen-rich atmosphere, similarly as in a dense interstellar cloud, could increase the fractional ionization via charge-transfer reactions of molecular ions (Oppenheimer & Dalgarno 1974). If the collision produces ionization, a secondary electron is created and is randomly assigned an isotropically distributed pitch angle and an energy, using an integral form of the formula of Green & Sawada (1972) and Jackman et al (1977) based on the laboratory results of Opal et al (1971) …”

Section: Photolytic and Electron-impact Processes In The Upper Atmospmentioning

confidence: 99%

Heating efficiency in hydrogen-dominated upper atmospheres

Shematovich

Ionov

Lämmer

2014

A&A

124

106

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Context. The heating efficiency η hν is defined as the ratio of the net local gas-heating rate to the rate of stellar radiative energy absorption. It plays an important role in thermal-escape processes from the upper atmospheres of planets that are exposed to stellar soft X-rays and extreme ultraviolet radiation (XUV). Aims. We model the thermal-escape-related heating efficiency η hν of the stellar XUV radiation in the hydrogen-dominated upper atmosphere of the extrasolar gas giant HD 209458b. The model result is then compared with previous thermal-hydrogen-escape studies, which assumed η hν values between 10-100%. Methods. The photolytic and electron impact processes in the thermosphere were studied by solving the kinetic Boltzmann equation and applying a Direct Simulation Monte Carlo model. We calculated the energy deposition rates of the stellar XUV flux and that of the accompanying primary photoelectrons that are caused by electron impact processes in the H 2 → H transition region in the upper atmosphere. Results. The heating by XUV radiation of hydrogen-dominated upper atmospheres does not reach higher values than 20% above the main thermosphere altitude, if the participation of photoelectron impact processes is included. Conclusions. Hydrogen-escape studies from exoplanets that assume η hν values that are ≥20% probably overestimate the thermal escape or mass-loss rates, while those who assumed values that are <20% produce more realistic atmospheric-escape rates.

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Section: Photolytic and Electron-impact Processes In The Upper Atmospmentioning

confidence: 99%

Heating efficiency in hydrogen-dominated upper atmospheres

Shematovich

Ionov

Lämmer

2014

A&A

124

106

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“…In the PIC method, electron-neutral collisions such as elastic, excitation and ionization processes are included and are treated by the Monte Carlo method and Null-collision method. 7) Electron energy losses are different among these collision processes. The present calculation treats xenon as a neutral particle.…”

Section: Calculation Methodsmentioning

confidence: 99%

Analysis of Electron and Microwave Behavior in Microwave Discharge Neutralizer

Masui

Tashiro

Yamamoto

et al. 2006

Trans. Japan Soc. Aero. S Sci.

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In the MUCES-C mission conducted by JAXA (Japan Aero Exploration Agency), a microwave neutralizer is mounted with a microwave ion engine on the HAYABUSA space probe. The neutralizer consists of an L-shaped antenna to inject microwaves and samarium cobalt magnets to provide ECR (electron cyclotron resonance). Plasma production of a higher density than the cutoff density is expected in the discharge chamber, but the neutralizer is so small that high-precision measurements using a probe are difficult. To clarify the plasma production mechanism in the microwave neutralizer, numerical analysis was conducted using a code coupling PIC (particle-in-cell) method, and a FDTD (finitedifference-time-domain) method. This paper describes effects caused by varying magnetic field configuration and antenna position in the neutralizer. The calculation results show that bringing the antenna closer to the ECR region is effective for plasma production.

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“…As the primary electrons are absorbed within the atmosphere, their kinetic energy is degraded through elastic collision with atmospheric molecules, leading to the emission of atmospheric secondary electrons . According to laboratory measurements of Opal et al (1971), the energy distribution of secondary electrons from O 2 and N 2 does not depend on the energy of the primary electrons and is within the sub-kiloelectronvolt energy range. To study the "tertiary" electron emission (TEE) from MSPs, we have used an atmospheric secondary differential electron flux measured at 105 km altitude under auroral conditions (see Fig.…”

Section: Electron Precipitation and D-region Conditionsmentioning

confidence: 99%

Secondary electron emission from meteoric smoke particles inside the polar ionosphere

2016

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Abstract. The charging by secondary electron emission (SEE) from particles is known as a significant charging process in astrophysical plasmas. This work aims at evaluating the significance of SEE for charging of meteoric smoke particles (MSPs) in the Earth's polar atmosphere. Here, the atmosphere is subject to a bombardment of energetic electrons from the magnetosphere (and partly the sun). We employ the SEE formalism to MSPs in the upper mesosphere using electron precipitation fluxes for three different precipitation strengths. In addition, we address the possible effect of tertiary electron emission (TEE) from MSPs induced by atmospheric secondary electrons for one precipitation case. The SEE and TEE rates from MSPs of different sizes are compared to plasma attachment and photodetachment and photoionization rates of MSPs. The needed concentration of electrons and ions have been modeled with the Sodankylä Ion and Neutral Chemistry (SIC) model with included electron precipitation spectra as an additional ionization source. We find that secondary electron emission from MSPs is not a relevant charging mechanism for MSPs. The electron attachment to MSPs and photodetachment of negatively charged MSPs are the most important processes also during energetic electron precipitation.

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Measurements of Secondary-Electron Spectra Produced by Electron Impact Ionization of a Number of Simple Gases

Cited by 380 publications

References 22 publications

Heating efficiency in hydrogen-dominated upper atmospheres

Heating efficiency in hydrogen-dominated upper atmospheres

Analysis of Electron and Microwave Behavior in Microwave Discharge Neutralizer

Secondary electron emission from meteoric smoke particles inside the polar ionosphere

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