Simulating Fusion Plasmas
Thomas Hayward-Schneider
Max Planck Institute for Plasma Physics (IPP)
Garching, Germany
EUM ’22, 27th January 2022
@hattom
Disclaimer: these views are my own and do not reflect those of my employer.
Outline
- Fusion
- What is fusion?
- How does it work?
- Why do we care?
- Why is it hard?
- Tokamaks & ITER
- Modelling
- Outlook
Fusion
- “Nuclear fusion is a reaction in which two or more atomic nuclei are combined to form one or more different atomic nuclei and subatomic particles”
– Wikipedia: “Nuclear fusion”
- An ideal and clean source of electricity
- The process used by the Sun
- It’s the “opposite” of Nuclear fission (which releases power by splitting big atoms)
- Mass difference \(\Rightarrow\) \(E=mc^2\) \(\Rightarrow\) voila
Fusion
- Specifically, are there 2 small things which we can get to join together, Step ??? = Profit
- Nuclei are + charged, repel each other
- Must hit each other with high energy to convince them otherwise
- “DT” wins: Deuterium (\(^2\)H) = heavy hydrogen; Tritium (\(^3\)H) = extra-heavy hydrogen
- Gives us our target fusion reaction: \(^2\)D + \(^3\)T \(\Rightarrow\) \(^4\)He + \(^1\)n + 17.6 MeV
- Peak at temperatures > 100 M °C
N.B. Different from the fusion process in the Sun
Fusion
- In summary:
- Get some Deuterium and Tritium
- Heat them to >100 M °C
- Make sure they stay put
- Fusion happens
- Profit
Fusion & Plasma
- Hydrogen at 100 M °C
- c.f. solar core (15 M °C); solar surface (5000 °C)
- Fusion labs are hottest places in the solar system
- Plasma – 4th state of matter (solid, liquid, gas, plasma):
- Gases break apart at very high temperatures / low densities
- Electrons and ions separate \(\Rightarrow\) all particles in a plasma are charged!
- Charged particles interact with electromagnetic fields
- Most of “stuff” in space, plus the outer planets, is a plasma
- A lot of fusion physics is plasmas physics
Idea: use magnetic fields to “hold” our plasma
\(\to\) Magnetic Confinement Fusion
“We say that we will put the sun into a box. The idea is pretty. The problem is, we don’t know how to make the box.”
– Pierre-Gilles de Gennes
Magnetic confinement
Red: no magnetic field
Kicked particle flies away
Blue: magnetic field (into screen)
Kicked particle gyrates
Magnetic confinement