Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: ULYSSES observations

Details Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: ULYSSES observations Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: ULYSSES observations

Jun 1995

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1995sowi.conf..105f&link_type=abstract

Los Alamos National Lab., International Solar Wind 8 Conference, p. 105

Computer Science

Electron Impact, Ionization, Shock Waves, Solar Activity Effects, Solar Wind, Stellar Mass Ejection, Shock Wave Interaction, Interstellar Gas, Ionization Coefficients, Charge Exchange, Charge Transfer, Electron Distribution, Electron Energy, Heliosphere, Photoionization, Ulysses Mission, Helium, Hydrogen

Scientific paper

During average solar wind flow conditions at 1 AU, ionization rates of interstellar neutrals that penetrate into the inner heliosphere are dominated by charge exchange with solar wind protons for H atoms, and by photoionization for He atoms. During occurrences of strong, coronal mass ejection (CME)-driven interplanetary shock waves near 1 AU, electron impact ionization can make substantial, if not dominating, contributions to interstellar neutral ionization rates in the regions downstream of the shocks. However, electron impact ionization is expected to be relatively less important with increasing heliocentric distance because of the decrease in electron temperature. Ulysses encountered many CME-driven shocks during its journey to and beyond Jupiter, and in addition, encountered a number of strong corotating interaction region (CIR) shocks. These shocks generally occur only beyond approximately 2 AU. Many of the CIR shocks were very strong rivalling the Earth's bow shock in electron heating. We have compared electron impact ionization rates calculated from electron velocity distributions measured downstream from CIR shocks using the Ulysses SWOOPS experiment to charge-exchange rates calculated from measured proton number fluxes and the photoionization rate estimated from an assumed solar photon spectrum typical of solar maximum conditions. We find that, although normally the ratio of electron-impact ionization rates to charge-exchange (for H) and to photoionization (for He) rates amounts to only about one and a few tens of percent, respectively, downstream of some of the stronger CIR shocks they amount to more than 10% and greater than 100%, respectively.

Affiliated with

Also associated with

No associations

Rating

Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: ULYSSES observations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: ULYSSES observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electron impact ionization rates for interstellar neutral H and He atoms near interplanetary shocks: ULYSSES observations will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-760505