Abstract
We measure the deuterium density, the parallel drift velocity, and parallel and perpendicular temperatures (T∥, T⊥) in non-Maxwellian plasmas at ASDEX Upgrade. This is done by taking moments of the ion velocity distribution function measured by tomographic inversion of five simultaneously acquired spectra of Dα-light. Alternatively, we fit the spectra using a bi-Maxwellian distribution function. The measured kinetic temperatures (T∥ = 9 keV, T⊥ = 11 keV) reveal the anisotropy of the plasma and are substantially higher than the measured boron temperature (7 keV). The Maxwellian deuterium temperature computed with TRANSP (6 keV) is not uniquely measurable due to the fast ions. Nevertheless, simulated kinetic temperatures accounting for fast ions based on TRANSP (T∥= 8.3 keV, T⊥ = 10.4 keV) are in excellent agreement with the measurements. Similarly, the Maxwellian deuterium drift velocity computed with TRANSP (300 km s-1) is not uniquely measurable, but the simulated kinetic drift velocity accounting for fast ions agrees with the measurements (400 km s-1) and is substantially larger than the measured boron drift velocity (270 km s-1). We further find that ion cyclotron resonance heating elevates T∥ and T⊥ each by 2 keV without evidence for preferential heating in the Dα spectra. Lastly, we derive an expression for the 1D projection of an arbitrarily drifting bi-Maxwellian onto a diagnostic line-of-sight.
| Original language | English |
|---|---|
| Article number | 036017 |
| Number of pages | 12 |
| Journal | Nuclear Fusion |
| Volume | 58 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - 1 Feb 2018 |
Funding
We thank the ITPA energetic particle physics topical group for its support. This work has been carried out within the framework of the EUROfusion Consortium and has received funding from the Euratom research and training programme 2014–2018 under grant agreement No 633053. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
Keywords
- anisotropic plasma
- bi-Maxwellian
- deuterium density
- deuterium rotation
- deuterium temperature
- velocity-space tomography
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