title Test model H and He atoms in Case B limit
c grid over nebular range of density and temperature to check Case B H & He
c
c commands controlling continuum =========
laser 5 Ryd
ionization parameter -2
c
c commands for density & abundances =========
init "hheonly.ini"
hden 2. vary
grid 2 6 2
c
c commands controlling geometry  =========
stop zone 1
c
c other commands for details     =========
normalize to "He 2" 4686
case b hummer no Pdest no photoionization
no scattering escape 
c prevent H I excited levels from being predicted
atom H-like element hydrogen resolved levels 3
constant temperature 4.
c
c commands controlling output    =========
atom H-like print levels 
save overview "limit_caseb_he_den.ovr"
save performance "limit_caseb_he_den.per"
save monitors "limit_caseb_he_den.asr"
c 
c commands giving the monitors    =========
monitor Case B H-like Helium   error 0.09 range 1000A to 10000A
c 
c limit_caseb_he_den.in 
c class limit 
c ========================================
c 

this tests the predicted He II spectra in the Case B limit.

this effectively turns off hydrogen to avoid the problem with every
other heII line lying beneath an HI line.  this is done by reducing
the number of levels for H I.

this asserts the values are within 9% for the standard T = 1e4K and
a range of densities.  Actually they are all nearly within a few
percent except at the lowest temperature of 5000K.