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P: Fachverband Plasmaphysik
P 8: Helmholtz Graduate School HEPP II
P 8.2: Talk
Tuesday, March 29, 2022, 14:25–14:50, P-H12
TALIF on H2 Plasmas and its Application to Negative Ion Sources — •Frederik Merk, Christian Wimmer, Stefan Briefi, and Ursel Fantz — Max-Planck-Institut für Plasmaphysik, Garching, Germany
Two-photon absorption laser induced fluorescence (TALIF) is a tool to determine both the density and the velocity distribution function of ground state H atoms in H2 plasmas. This is done by using a pulsed, frequency tripled dye laser (resulting in 205.08 nm radiation) in order to excite the atoms. The subsequent fluorescence radiation is collected for diagnostic purposes.
In H−/D− ion sources, the main mechanism of H− production is the H atom conversion at a (caesiated) low work function surface. This raises the need for a deeper understanding of the H atom dynamics close to that surface. Therefore a TALIF setup is newly installed at the H−/D− ion source BATMAN Upgrade (plasma created with 100 kW of RF power) which comes with multiple challenges due to the high voltage environment of the ion source (45 kV) and the complexity of the diagnostic itself. Thus, to gain experience beforehand, TALIF was installed at a planar ICP (600 W, 13.56 MHz). In order to give context to the TALIF measurements, optical emission spectroscopy is performed on the experiment and evaluated with a collisional radiative model for the determination of basic plasma parameters.
Results of TALIF measurements are presented for the planar ICP unsing H2, a H2/He mixture and D2 as working gases as well as results of the applications to BATMAN Upgrade.