Conveners
Runaway Electrons, Disruptions, and Diagnostics
- Tünde Fülöp (Chalmers University of Technology)
The currently envisaged method for disruption mitigation in ITER is to use massive material injection. One of the injection schemes considered is a two-stage shattered pellet injection (SPI), with a pre-disruption diluting deuterium injection followed by a neon injection aiming to radiatively dissipate the plasma energy content [1]. It was recently shown [1] that it will likely be possible to...
During the current quench in ASDEX Upgrade (AUG) disruptions, created by massive gas injection (MGI) to study runaway electron (RE) physics [1], Alfvénic activity is visible in the 300-800 kHz range. An example is presented in figure 1. These modes are analysed as potential runaway electron mitigation candidates [2]. With the help of a mode tracing algorithm, we classified the mode behaviour...
Kinetic instabilities in the MHz range have been observed during current quench in DIII-D disruption experiments (A. Lvovskiy et al., PPCF 60, 124003 (2018)). These instabilities are correlated with the RE loss happening at the beginning of disruption. In this work we use a MHD-kinetic code M3D-C1-K to simulate the excitation of this instability. It is found that this mode lies in the fast...
Post-disruption runaway electron (RE) beams can carry majority of flattop current and loss of RE confinement could be detrimental for continuous safe operation of tokamaks. Synchrotron emission (SE) is a great diagnostic tool for in-flight high-energy REs, but since it depends on both runaway electron density nRE and pitch angle θ, to understand RE evolution from SE, an independent measure of...
Runaway electrons (RE) in a tokamak can deposit a significant quantity of energy onto the plasma facing components and therefore represent a threat to ITER and next step fusion devices. This contribution presents the Runaway Electron Imaging Spectroscopy (REIS) diagnostic, designed to collect spectra and images produced by the RE synchrotron radiation emission. The system is composed of...
Fast-ion distribution functions in the MeV-range can be diagnosed by neutron emission spectroscopy (NES) and gamma-ray spectroscopy (GRS). For a given fast-ion distribution function and diagnostic energy bin, a measurement signal will have contributions originating from various fast-ion orbits [Ref1][Ref2]. These contributions depend on the sensitivity of the diagnostic in orbit phase space,...
