Charged Fusion Product Plasma Diagnostics in Spherical Tokamaks
Abstract
Charged fusion products from the D(d,p)t reaction, protons (p) and tritons (t), can be detected to obtain time and position dependent information on the fusion reaction profile in plasmas heated with neutral particles beams. We have developed a prototype instrument consisting of charged particle detectors with ion-implanted-silicon surface barrier detectors. Each detector is combined with two replaceable collimators in such a way that it can accept protons and tritons emitted from a well-defined area inside the plasma. The detectors thus provide curved views across the plasma volume. Combining the data of all six detectors allows one to study changes in the reaction profile with an expected time resolution of about . These changes are mainly due to slow variations in the neutral beam density profile, as well as rapid changes resulting from MHD instabilities. With an envisioned energy resolution of it will be also possible to study proton energy spectra containing the information on the plasma fast ion distribution function. The anticipated proton energy spectra have been calculated analytically as well as modeled using Monte Carlo methods. The effect of the fusion reaction cross section anisotropy on the observed rates have been analyzed as well as the effect of the magnetic field on the detector acceptance has been studied. The emissivity profile has been modeled for a specific plasma discharge from the MAST 2013 experimental campaign using the PPPL code TRANSP including a recent model for fast ion transport. The calculated proton rates have been compared to the measured ones to investigate the origin of a large discrepancy between experimental data and standard TRANSP results. A graphic user interface was developed for optimizing detector orientation and data analysis. Furthermore, the new hardware was implemented in the online data acquisition system and its general performance and capabilities were improved.
Subject Area
Plasma physics|Physics
Recommended Citation
Netepenko, Alexander, "Charged Fusion Product Plasma Diagnostics in Spherical Tokamaks" (2019). ProQuest ETD Collection for FIU. AAI29391245.
https://digitalcommons.fiu.edu/dissertations/AAI29391245