;20161228 Ali ;calculates Martian exospheric neutral O and H densities (or cometary H2O), ;assuming a spherically symmetric neutral exosphere (cometary netural coma) ;inputs: ; rtot: radial distance in "meters" from the center of Mars (comet) ; species: neutral species name (string) ; o: oxygen ; h: hydrogen ; h2: H2 ; css: comet siding spring ;output: density at rtot in "cm-3" ;keyword plot_exoden ignores rtot and plots the radial density profile for the given species function mvn_pui_exoden,rtot,species=species,plot_exoden=plot_exoden if keyword_set(plot_exoden) then begin rtot=1e6*(3+findgen(98)) ;radius (m) (3000 to 100,000 km) p=plot(mvn_pui_exoden(rtot,species=species),rtot/1e3,/xlog,/ylog,xtitle='$Neutral Density (cm^{-3})$',ytitle='Radial Distance (km)') return,'plot created.' endif qqo=5e22 ; for Mars O exosphere (m-0.9) fit to Rahmati et al., 2014 (Phiesc=9e7 cm-2 s-1) qqh=4e27 ; for Mars H exosphere (m-0.3) fit to Feldman et al., 2011 (Nexo=2.5e5 cm-3, Texo=200 K, Phiesc=8e7 cm-2 s-1) qh2=2e38 ; for Mars H2 exosphere (m1.5) fit to Liouville (same exo parameters as H) nno=qqo/((rtot-2400e3)^2.1) ;O density (m-3) nnh=qqh/((rtot-2700e3)^2.7) ;H density (m-3) nh2=qh2/((rtot-2700e3)^4.5) ;H2 density (m-3) qqcss=1e28 ;comet H2O production rate (s-1) vout=1e3 ;comet outflow speed (m) nncss=qqcss/(4.*!pi*rtot^2*vout) ;comet coma H2O density (m-3) case strlowcase(species) of 'o':nnn=nno 'h':nnn=nnh 'h2':nnn=nh2 'css':nnn=nncss endcase return,1e-6*nnn ;cm-3 end