Measurements of Isat fluctuations
#Motivation Remember the good old days when theory predicted that tokamak confinement was absolutely fantastic? You probably don’t, it was a very long time ago. Since then, we’ve seen evidence that plasma confinement in tokamaks is, sadly, deteriorated by several processes - and edge turbulence is one of them. Why is the edge turbulent? Where is the turbulence strongest? How does the turbulence look in single-probe measurements? You’ll find out in this task!
#Task outline
- Learn about turbulence in tokamaks: why, where, and why it matters to us so much
- Get acquainted with probe measurements (Langmuir probe theory & real probes on GOLEM)
- Perform experiments with the rake probe
- Pins in the \(I_{sat}\) regime, we measure density and temperature spikes = turbulence
- Interpret the data using Python (or any language you feel comfortable with, but then you won’t get much advice from me :( )
- Mainly we’ll be drawing fluctuation distribution functions and finding their properties: relative fluctuation level, skewness and kurtosis
#Resources
- D. A. D’Ippolito et al, Convective transport by intermittent blob-filaments: Comparison of theory and experiment, Physics of plasmas 18, 060501 (2011), particularly section IV (the entire thing is really long)
- Rake probe wiki page
- A YouTube introduction into moments of distribution functions