Erlangen 2018 – scientific programme
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P: Fachverband Plasmaphysik
P 20: Plasma Wall Interaction II - Poster
P 20.6: Poster
Wednesday, March 7, 2018, 16:15–18:15, Zelt West
A piezoelectric particle injector for ASDEX Upgrade — •Alexander Bauer1,2, Volker Rohde1, Rudolf Neu1,2, and the ASDEX Upgrade Team1 — 1Max Planck Institute for Plasma Physics, Garching, Germany — 2Technical University Munich, Garching, Germany
In the Tokamak ASDEX Upgrade a significant amount of small (W) tungsten spheres with the size of over 1 µm is found during dust investigations, which are presumably produced by arcing. Macroscopic particles have a higher penetration probability into the core plasma compared to atoms, possibly causing a substantial W influx. To study their penetration a small injector, developed at KSTAR [1], will be put in operation at ASDEX Upgrade. In this contribution we report on laboratory investigation on characterization and commissioning. The mechanic is driven by a piezo motor that compresses a spring. When the spring expands a cylinder gets accelerated and injects particles supplied from a small reservoir. The device is of compact size and is capable to operate under vacuum conditions and strong magnetic fields. During the characterization different parameters were investigated. Tests were carried out at atmospheric pressure and under vacuum, mostly using high speed cameras to record the particle trajectories. Different methods are used to illuminate the launched particles. In the plasma the particles will be heated and get visible due to them glowing. For the injected amount of particles tests resulted in a W mass per shot of 24 ± 11 mg. The videos have shown initial velocities of 1.55 m/s in air and ranges of 8 cm. [1] H.Y.Lee et al., RSI, 85 (2014), 11D862