More on x-rays

Well, photons. The Klein-Nisch formula gives compton (x-rays) and Thompson (lower energy than x-rays) cross-sections for scattering off electrons. Data can also be found for absorption, ionisation, dissociation, Rayleigh/Mie (visible scattering off dust) and Raman (absorption, plus re-emission at another wavelength). This is all photons do. Well, in my model it will be... Plus need to establish the effect of the Sun being an extended source, and see if I can get my photons to curve...

Need differential pdfs from each type of scattering plus total cross-sections.

One run has finished so far. 40eV completed its SD+2 run, was analysed, recoded and set off again without grade changes.

Ok, after a bit of research, it probably won't matter (ok, certainly won't matter) if I keep the backscatter ratio at 0.5 as that is what it is below about 0.2MeV (far more energetic than 1nm). There isn't anything to worry about so far as energy transfer after all, so just need to put compton scattering total cross-section (which I have) into the program as a normal, scattering (incoherent) cross-section. Then, absorption, dissociation and ionisation ones go in as normal. Rayleigh/Mie can't be used as there's no dust in the models, so that just leaves Raman, which has already been stuck in there. Thompson is implictly included through the Compton computation as mentioned above. Ok, I'm ready to rock...

Have scraped together a load of cross-sections for a 1nm grid of x-ray fluxes. Need a few molecular ones, but have compton ones, plus a few photoionisation and absorption ones for elements - enough, at least, to interpolate the rest from.

Have also had another cloudy day at Mill Hill. 100% cloud cover at least...

H3+ profile has come through from Makenzie.

Quick note

Some x-ray work today, using NIST. The difficulty is establishing exactly what is required. I need to define a wavelength or energy grid that provides a smooth baseline over the solar2000 additional grid, then spot and add on any resonances that prove to be important - lines where solar flux is considerably higher/lower than normal, or a particular species is sensitive too.

As these are x-rays, it may be more appropriate to use an energy grid. But as I have a single model that should deal smoothly with x-rays, EUV, visible etc, once its been extended, I need a standardised grid...

More tomorrow

Bits and bobs

Upgrade to titan's IDL install affected to allow running of Solar2000. Now works

Have been thinking again about the suicidal x-ray problem. Suicidal x-rays refer to the effect that an x-ray flux impacting on a neutral atmosphere will have. The atmosphere gets ionised by the impact, creating electrons. Electrons have a similar size to the wavelength of x-rays, which means Compton scattering cross-sections see their peak in the x-ray region. This, in turn means that x-rays get scattered more by the electrons they create. The effect of scattering is that x-rays lose energy and become EUV or less, meaning the x-ray flux kills itself. The chapman function method of calculating this is to apply the cf and have a compton scattering addition to the path length, ignoring the creation of EUV photons and concurrent destruction of x-rays, not to mention the directional effects of the scattering.

Another thought experiment has included space charges created in the aurorae and the currents created by the churning of background electrons to remove it. Though this effect is well known as it causes the induced currents that knock out powerlines and stations in powerful substorms, the heating effect in the upper atmosphere doesn't seem to be as well considered...

Of course, the majority of the work done today was on the Mars model, getting hold of, interpolating and extrapolating NO ionisation cross-sections. That is nitrogen monoxide, not "no" cross-sections... though the feeling did occur...

Saturn5000 slot run of 50eV in SD+2 mode completed. Analysis raised 50eV grade to 2i. Recoded as SD+C and set off again.