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Publications in Scientific Journals:

R. Arredondo Parra, R. Moreno Quicios, B. Ploeckl, G. Birkenmeier, A. Herrmann, G. Kocsis, F. Laggner, P. Lang, T. Lunt, R. Macian-Juan, V. Rohde, G. Sellmair, T. Szepesi, E. Wolfrum, W. Zeidner, R. Neu, . ASDEX Upgrade Team:
"A compact lithium pellet injector for tokamak pedestal studies in ASDEX Upgrade";
Review of Scientific Instruments, 87 (2016), 0235081 - 02350810.



English abstract:
Experiments have been performed at ASDEX Upgrade, aiming to investigate the impact of lithium in
an all-metal-wall tokamak and attempting to enhance the pedestal operational space. For this purpose,
a lithium pellet injector has been developed, capable of injecting pellets carrying a particle content
ranging from 1.82 ⇥ 1019 atoms (0.21 mg) to 1.64 ⇥ 1020 atoms (1.89 mg). The maximum repetition
rate is about 2 Hz. Free flight launch from the torus outboard side without a guiding tube was
realized. In such a configuration, angular dispersion and speed scatter are low, and a transfer efficiency
exceeding 90% was achieved in the test bed. Pellets are accelerated in a gas gun; hence special care
was taken to avoid deleterious e↵ects by the propellant gas pulse. Therefore, the main plasma gas
species was applied as propellant gas, leading to speeds ranging from 420 m/s to 700 m/s. In order
to minimize the residual amount of gas to be introduced into the plasma vessel, a large expansion
volume equipped with a cryopump was added into the flight path. In view of the experiments, an
optimal propellant gas pressure of 50 bars was chosen for operation, since at this pressure maximum
efficiency and low propellant gas flux coincide. This led to pellet speeds of 585m/s 32m/s. Lithium
injection has been achieved at ASDEX Upgrade, showing deep pellet penetration into the plasma,
though pedestal broadening has not been observed yet.

Created from the Publication Database of the Vienna University of Technology.