Bits and pieces

Arranged six month chat...

Went to Mill Hill

Got back late

Mill Hill

Another clear night with observations of Saturn, a double star and some cluster or other.

One run finished overnight and was analysed. Saturn12 was the 12eV 0.9 BSR run, which finished. An email from IS states that further restrictions are now in effect around Keter, so any of these runs that fail have simply failed for good.

Bits, pieces (and that's just me)

First thing was dropping off the poster at the graduate school poster competition, under Alan's orders

Then marked half the remaining scripts, as well as correcting the already marked scripts for an error in the model answers...

Seminar finesed and transfered to a laptop for presentation

Emails sent to arrange cover for my extra demonstation session from Mill Hill

Seminar performed

Looong night at Mill Hill, with observations of...

The International Space Station (naked eye)
The Orion Nebula (Fry, Radcliffe, plus CCD on Meade)
The Moon (Fry, Radcliffe)
Saturn (Radcliffe)
Cloud (naked eye, Fry, Radcliffe, Meade)

...enclosing an additional hour of work. So, marking left for tomorrow

More stuff

One run finished overnight:

Saturn50 50eV SD-1. This was analysed, recoded as 12eV SD-1 and set off again. No grade changes.

Mill Hill

Quick note

Two completed runs:

Saturn5000 completed the 50eV SD+1 run, was analysed, recoded and set off as the 40eV SD+1 run (with a new 31 day runscript). Analysis saw no grade changes, but it did mean 22 runs were remaining to go - ie twice the number of available slots. Also, all 50eV runs and all 40eV runs were either done or going, indeed that is true for all energies except 12eV.

Saturn40 completed the 40eV SD+C run. This was analysed, recoded and reset off as the 12eV SD+C run. Analysis revealed no grade changes, but overall, we hit the 90% mark, so far as runs done goes.

Also spent half the (satur)day at Mill Hill, helping with the SPA tours.

Marking

...and a small interlude with a phone call from BAS asking about upward flowing electrons.

Three mechanisms:

Scattering - electrons are just particles bouncing around. They occasionally bounce back, indeed plenty do, though this creates a small upward flux far lower than the downward flux (and increasingly comparitively smaller the higher the energy of the forward flux).

Charge reallignment - this affects any ionising thing that enters the atmosphere. Ionisation leads to most the momentum going to the small electron seperating from the big particle, leaving a static positive layer in the position of greatest ionisation and a layer where the electrons (those that don't themselves then head up) end up. Background electrons then move away from the negative layer towards the positive layer to neutralise this.

Birkland currents - dumping massive amounts of negative charge into the ionosphere leads to a negatively charged ionosphere (I know, I was as surprised as you are...), which cannot be. This is negated by a current of opposite polarity completing the circuit between the ionosphere and the magnetosphere. This takes the form of either protons flowing in or electrons flowing out, or a combination of the two.

There you are.

Also did some marking

...as well as some preparation for taking people on a tour of Mill Hill tomorrow. Scary. For them, not me...

Grrr

Marking

Problem class

Marking

Mill Hill

Marking

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.

Couple of runs

Much of the day has been taken up with Mill Hill and taking up Outreach leaflets to the observatory, but beforehand two runs did finish, the analysis of which was kept until afterwards.

The first was Saturn1000 finishing off the 1keV GS runs with GS1m. This was recorded and then recoded as 100keV GS1m run and set off. Later analysis was as expected. No grade changes.

The second was Saturn12000, doing a 1keV SD run (SD+1). This was recorded, recoded as SD+C and set off, making it the penultimate 1keV run. Analysis as expected. SD grade changes to a first. It is 70% done, GS is more than 80% done and BSR is 90% done. Overall, just over 80% done.