Cross Sections for Collisions of Electrons and Photons with Oxygen Molecules

Itikawa, Yukikazu; Ichimura, Atsushi; Onda, Ken; Sakimoto, Kazuhiro; Takayanagi, Kazuo; Hatano, Yoshihiko; Hayashi, Makoto; Nishimura, Hiroyuki; Tsurubuchi, Seiji

doi:10.1063/1.555841

Cited by 321 publications

(157 citation statements)

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“…The photoelectron flux is calculated with with an electron-two-stream code [Gustavsson and Eliasson, 2008]. The photoelectron production we calculate with photoionization cross sections compiled by Itikawa et al [1986Itikawa et al [ , 1989 and Itikawa and Ichimura [1990] and solar EUV fluxes from SOLAR2000 [Tobiska and Bouwer, 2006] with one scale factor for wavelengths below 1200 Å and another for wavelengths below 250 Å. In Figure 7 the scaled EUV photon fluxes are shown together with the EUV fluxes from SOLAR2000.…”

Section: Appendix A: Electron Heating As a Means To Estimate Neutral mentioning

confidence: 99%

Rise and fall of electron temperatures: Ohmic heating of ionospheric electrons from underdense HF radio wave pumping

et al. 2010

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[1] Here we present electron temperature variations observed with incoherent scatter radar during a European Incoherent Scatter Scientific Association Heating experiment with high-frequency (HF) radio wave transmission at frequencies above the peak ionospheric critical frequency. The electron temperature increased from 2000 K up to 2800 K during the HF transmission periods. During the experiment both pump frequency and polarization were altered between pump pulses. The observed temperature variation is compared with numerical solutions to the electron energy equation with ohmic heating modeling the effect of the radio wave heating of the plasma. Agreement between observations and model is found to be good.

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Section: Appendix A: Electron Heating As a Means To Estimate Neutral mentioning

confidence: 99%

Rise and fall of electron temperatures: Ohmic heating of ionospheric electrons from underdense HF radio wave pumping

et al. 2010

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“…Cascade from the O I (3p 5D) term with the emission of a 7774 Ó photon provides a lower limit to the total emission cross section and is assumed to characterize the cross section shape above 100 eV (Erdman & Zipf 1987). We used Wells, Borst, & Zipf (1971) to deÐne the cross section shape from 20 to 100 eV and normalized the emission cross section at 100 eV to 7 ] 10~18 cm2, as given in Itikawa et al (1989).…”

Section: Model Constraintsmentioning

confidence: 99%

Excitation of the Ganymede Ultraviolet Aurora

Eviatar

Strobel

Wolven

et al. 2001

ApJ

100

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We analyze the ultraviolet aurorae observed on Ganymede by means of the Hubble Space T elescope and compare them to similar phenomena on Earth. We Ðnd that the tenuous nature of GanymedeÏs atmosphere precludes excitation of the aurora by high-energy electrons and requires a local acceleration mechanism. We propose the following as plausible mechanisms for generating both the continuous background emission and the intense auroral bright spots :1. Birkeland-type currents and associated magnetic ÐeldÈaligned electric Ðelds. 2. The stochastic heating of plasma electrons by the Landau damping of electron plasma oscillations generated by precipitated energetic electrons.We conclude that the electron density in the bright regions may attain local values as high as 105 cm~3.

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“…and Itikawa et al (1989). Total inelastic electron impact cross sections σ 1 and σ 2 and cross sections for the direct excitation of atomic O to the states ( 5 S • ) and ( 5 P ) are taken from the work of Jackman et al (1977).…”

Section: Volume Excitation Ratementioning

confidence: 99%

The generation of Ganymede's diffuse aurora through pitch angle scattering

2017

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Abstract. Diffuse auroral intensities of neutral atomic oxygen OI λ1356 Å emission on Ganymede due to whistler mode waves are estimated. Pitch angle diffusion of magnetospheric electrons into the loss cone due to resonant wave-particle interaction of whistler mode waves is considered, and the resulting electron precipitation flux is calculated. The analytical yield spectrum approach is used for determining the energy deposition of electrons precipitating into the atmosphere of Ganymede. It is found that the intensities (4-30 R) calculated from the precipitation of magnetospheric electrons observed near Ganymede are inadequate to account for the observational intensities ( ≤ 100 R). This is in agreement with the conclusions reached in previous works. Some acceleration mechanism is required to energize the magnetospheric electrons. In the present work we consider the heating and acceleration of magnetospheric electrons by electrostatic waves. Two particle distribution functions (Maxwellian and kappa distribution) are used to simulate heating and acceleration of electrons. Precipitation of a Maxwellian distribution of electrons can produce about 70 R intensities of OI λ1356 Å emission for electron temperature of 150 eV. A kappa distribution can also yield a diffuse auroral intensity of similar magnitude for a characteristic energy of about 100 eV. The maximum contribution to the estimated intensity results from the dissociative excitation of O 2 . Contributions from the direct excitation of atomic oxygen and cascading in atomic oxygen are estimated to be only about 1 and 2 % of the total calculated intensity, respectively. The findings of this work are relevant for the present JUNO and future JUICE missions to Jupiter. These missions will provide new data on electron densities, electron temperature and whistler mode wave amplitudes in the magnetosphere of Jupiter near Ganymede.

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Cross Sections for Collisions of Electrons and Photons with Oxygen Molecules

Cited by 321 publications

References 1 publication

Rise and fall of electron temperatures: Ohmic heating of ionospheric electrons from underdense HF radio wave pumping

Rise and fall of electron temperatures: Ohmic heating of ionospheric electrons from underdense HF radio wave pumping

Excitation of the Ganymede Ultraviolet Aurora

The generation of Ganymede's diffuse aurora through pitch angle scattering

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