= Propellant Plume Gas Scattering =

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=== H density versus altitude ===

||<|16> {{ attachment:geocoronaMarkup.png | | width=600 }} ||<)> '''alt km''' ||<)> '''radius km''' ||<)> '''#/m3''' ||
||<)>  1000 ||<)>  7378 ||<)> 21000e6 ||
||<)>  2000 ||<)>  8378 ||<)> 12000e6 || [[  HighApogeeConstruction | Construction perigee ]] ||
||<)>  5000 ||<)> 11378 ||<)>  3100e6 ||
||<)> 10000 ||<)> 16378 ||<)>   820e6 ||
||<)> 20000 ||<)> 26378 ||<)>   180e6 ||
||<)> 30000 ||<)> 36378 ||<)>    67e6 ||
||<)> 35786 ||<)> 42164 ||<)>    45e6 || GEO circular    ||
||<)> 40000 ||<)> 46378 ||<)>    35e6 ||
||<)> 50000 ||<)> 56378 ||<)>    22e6 ||
||<)> 60000 ||<)> 66378 ||<)>    14e6 ||
||<)> 69572 ||<)> 75950 ||<)>    11e6 || [[ HighApogeeConstruction | Construction apogee ]] ||
||<)> 70000 ||<)> 76378 ||<)>    10e6 ||
||<-3> [[attachment:geocoronaMarkup.png | image source ]] ||

. https://www.sciencedirect.com/science/article/pii/0022407372900052

||<-12> Estimated hydrogen mass per 1000 km height, 1.67e-27kg/H  ||
|| Altitude km || 1000   || 2000   || 10000  || 20000  || 30000  || 35786* || 40000  || 50000  || 60000  || 69572* || 70000  ||
|| Radius km   || 7378   || 11378  || 16378  || 26378  || 36378  || 42164* || 46378  || 56378  || 66378  || 75950* || 76378  ||
|| Volume km³  || 6.8e11 || 1.6e12 || 3.4e12 || 8.7e12 || 1.7e13 || 2.2e13 || 2.7e13 || 4.0e13 || 5.5e13 || 7.2e13 || 7.3e13 ||
|| #H /  m³    || 2.1e10 || 1.2e10 || 8.2e8  || 1.8e8  || 6.7e7  || 4.5e7  || 3.5e7  || 2.2e7  || 1.4e7  || 1.1e7  || 1.0e7  ||
|| H kg        || 240000 ||  32000 ||  4700  ||  2600  || 1900   || 1700*  || 1000   || 1500   || 1300   || 1300*  || 1200   ||

Less than 20 tonnes of hydrogen (and almost nothing else) above GEO, out to the bow shock.

===  Collision cross section table ===

|| Gas  || (nm)² || (nm)² with H₂ ||
|| H₂ 	|| 0.27  || 1.02     ||
|| He 	|| 0.21  || 0.99     ||
|| Ar 	|| 0.36  || 1.06     ||
|| O₂ 	|| 0.40  || 1.07     ||
|| N₂ 	|| 0.43  || 1.08     ||
|| CH₄  || 0.46  || 1.09     ||
|| CO₂  || 0.52  || 1.11     ||
|| Cl₂  || 0.93  || 1.22     ||

The second column is the combined collision cross section with an H₂ molecule ... the square of the sum of the square roots.

from [[ https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Kinetics/Modeling_Reaction_Kinetics/Collision_Theory/Collisional_Cross_Section | libretexts ]]

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