English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In a series of earlier papers, we have developed expressions for ion andelectron velocity distribution functions and theirvelocity moments at thepassage over the solar wind termination shock. As we have shown there, withintroduction of appropriate particle invariants and the use of Liouville`stheorem one can get explicit solutions for the resulting total downstreampressure adding up from partial pressure contributions of solar wind protons,solar wind electrons and pick-up protons. These expressions deliver in a firststep the main contributions to the total plasma pressure in the downstreamplasma flow and consistently determine the shock compression ratio. Here now westart out from these individual fluid pressures downstream of the shock andthereafter evaluate for the first time the shock-induced entropy production ofthe different fluids, when they are passing over the shock to the downstreamside. As is shown here, the resulting ion entropy production substantiallydeviates from earlier calculations using a pseudo-polytropic reaction of theions to the shock compression, with polytropies selected to describefluid-specific reactions at the shock passage similar to those seen by theVOYAGERs. From these latter models ion entropy jumps are derived that depend onthe pick-up ion abundance, while our calculations, to the opposite, deliver anabundance-independent ion entropy production which only depends on the shockcompression ratio and the tilt angle between the upstream magnetic field andthe shock surface normal. We also do show here that only when including thestrongly heated electrons into the entropy balance one then arrives at thetotal entropy production that just fulfills the thermodynamically permittedlimit.

Entropy generation at the multi-fluid MHD solar wind termination shock