Science Porn

[pocaracas]

poca, tell us more about how do you get a density profile from *one* antenna at the edge? Inquiring minds want to know

Also, is eta just some sort of number density of what and R the distance from the edge? And why does it have plateaus! And what does the H in H mode stand for?

Also, did many of the kids cry when you were done? srsly, I'd like to see how you sold that material to 12 year olds!

I just noticed that I didn't answer the questions!!

1. One antenna probes a line of sight along the midplane of the tokamak. It is then assumed that it is poloidally symmetric, that is it has the same density along a particular magnetic field line.... imagine my line going around this here cross-section:


2. eta_e is the electron density and the units are electrons per cubic metre.
2.1. R=4 is the wall (the antenna is a bit further out, but nothing's supposed to be there).
2.2. Plateaus in density appear due to a transport barrier that is present at the edge... plasma tends to move outward (you know... from hot to cold, in this case, core to edge), so it gets more or less equalized up to that barrier.
2.3. H stands for High confinement, as opposed to Low confinement. The profile I showed in my last post is an L-mode one.

3. No kids were harmed during the presentation, so none cried. 2 or 3 did struggle to stay awake.... but some 5 looked really awed by it... of course, this sort of pic helps:

[bonus!]

---

---

I had to explain everything in simple language... from magnetic fields due to electric currents, to the reverse, to atoms and electrons flying around and ionizing, and isotopes and nuclear fusion in tokamaks and in the sun...