title: A compact lithium pellet injector for tokamak pedestal studies in ASDEX Upgrade.
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 × 10(19) atoms (0.21 mg) to 1.64 × 10(20) 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 effects 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 585 m/s ± 32 m/s. Lithium injection has been achieved at ASDEX Upgrade, showing deep pellet penetration into the plasma, though pedestal broadening has not been observed yet.
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Arredondo Parra
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Moreno Quicios
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Ploeckl
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Birkenmeier
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Herrmann
authors.affiliation: Wigner RCP Institute for Particle and Nuclear Physics, 1121 Budapest, Hungary.
authors.forename: G
authors.initials: G
authors.lastname: Kocsis
authors.affiliation: Institute of Applied Physics, TU Wien, Fusion@ OAW, Wiedner Hauptstr. 8-10, 1040 Vienna, Austria.
authors.forename: F M
authors.initials: FM
authors.lastname: Laggner
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: P T
authors.initials: PT
authors.lastname: Lang
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Lunt
authors.affiliation: Technische Universität München, 85748 Garching, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Macian-Juan
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Rohde
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Sellmair
authors.affiliation: Wigner RCP Institute for Particle and Nuclear Physics, 1121 Budapest, Hungary.
authors.forename: T
authors.initials: T
authors.lastname: Szepesi
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Wolfrum
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: W
authors.initials: W
authors.lastname: Zeidner
authors.affiliation: Max Planck Institut für Plasmaphysik, Boltzmannstrasse 2, 85748 Garching, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Neu