Speaker
Description
Divertor detachment is the leading candidate for solving the heat exhaust problem in future fusion reactors. Key to understanding detachment is the interaction of the plasma with a background of neutral particles in the divertor region. Collisions of the plasma with these neutral background particles result in a rich range of physical and chemical processes, causing the plasma to dissipate its energy and momentum, and finally to recombine, preventing damage to the wall. Whereas charged particles are routinely diagnosed, information on neutral particles is often missing. The properties of neutral particles can be measured using active spectroscopy. At Magnum-PSI, a linear plasma generator that can simulate the high heat and particle flux conditions of future fusion reactors, two types of active spectroscopy are currently being developed: TALIF and CARS. In this poster an overview of the TALIF diagnostic is presented, see [1] for the CARS developments.
TALIF, Two photon Absorption Laser Induced Fluorescence, is a local measurement of the properties of H atoms in the electronic ground state. The spatially resolved TALIF profiles provide the atomic H density, temperature and flow velocity. TALIF data was taken over a broad range of plasma parameters in both the UPP and Magnum-PSI linear devices, providing a dataset that can be used to validate divertor models.
Calibrated data taken during various degrees of detachment will be presented. Also, two types of TALIF calibration are compared using either Xe or Kr as reference gases. We revisit measurements made by Elliott et al [2]. for the Xe:Kr relative calibration factor, and find a value of 0.181 ± 0.025, which differs from the earlier work by a factor of 5.
[1] K. Schutjes et al., This conference
[2] D. Elliott et al., Rev. Sci. Instrum. 87, 11E504 (2016)