title interstellar cloud irradiated by ism background
c
c commands controlling continuum =========
c this uses the Black continuum with no H-ionizing radiation,
c and with background cosmic rays
table ism
extinguish by a column of 22
// >>chng 12 apr 09, scale factor will result in Williams et al CR rate 
// this old rate is used to maintain history of changes
cosmic rays background linear 0.1266
c
c commands for density & abundances =========
hden 0 vary
grid from -3 to 2 in 0.5 dex steps
init file="ism.ini"
c this turns on ism abundances and grains
abundances ism
c
c commands controlling geometry  =========
c set sphere since matter in all directions
sphere 
stop temperature linear 10
stop thickness 0.1 linear parsecs
stop zone 1 
c
c other commands for details     =========
c this prevents continuum pumping from exciting H0
case b
c
c commands controlling output    =========
c this model has no heavy element molecules, because H2 does not
c really fully form, since Lyman bands are not self-shielded
normalize to 157.6m "C  2"
save performance "ism_grid.per"
save grid "ism_grid.grd" last
save averages "ism_grid.avr" last
temperature hydrogen 1 
end of averages
save monitors "ism_grid.asr" last
save overview "ism_grid.ovr" last
save dr "ism_grid.dr"
save heating "ism_grid.het" 
save coolign "ism_grid.col" 
save xspec mtable "ism_grid.fit" range 0.1 3 keV
save temperature "ism_grid.tem" 
c
c commands giving the monitors    =========
c this is a special version of the monitors that does a series of models 
// >>chng 08 feb 11, from 776 to 811 for sim 5, cr&secondary heat efficiency
c sert tempe hydro 1 9942 .05 grid 8575 6468 3606 776 304 169 103 66.2 44.1 31.3
monitor tempe hydro 1 grid "ism_grid.dat" .05
c
c ism_grid.in
c class ism 
c ========================================

this shows an S-curve calculation - make plot showing density as X-axis
and gas pressure (nT) as y-axis

the gas is ionized by the galactic background.  the density varies between
1e-3 and 100 cm-3.  this is the full range found in the diffuse ism.
The components that are produced are 
CNM - cold neutral medium, density ~ 40 cm-3
WNM - n ~ 0.5 cm-3, 
WIM - warm ionized medium, n ~ 0.25 cm-3
HIM - hot ionized medium, n ~ 1e-3 cm-3, calculation DOES NOT 
      reproduce observed temperature of HIM - we get ~1e4K but
      observed is ~1e6 K.  HIM is shock, not photo, ionized