title: Fast piezoelectric valve offering controlled gas injection in magnetically confined fusion plasmas for diagnostic and fuelling purposes.
abstract: In magnetically confined fusion plasmas controlled gas injection is crucial for plasma fuelling as well as for various diagnostic applications such as active spectroscopy. We present a new, versatile system for the injection of collimated thermal gas beams into a vacuum chamber. This system consists of a gas pressure chamber, sealed by a custom made piezo valve towards a small capillary for gas injection. The setup can directly be placed inside of the vacuum chamber of fusion devices as it is small and immune against high magnetic fields. This enables gas injection close to the plasma periphery with high duty cycles and fast switch on/off times ≲ 0.5 ms. In this work, we present the design details of this new injection system and a systematic characterization of the beam properties as well as the gas flowrates which can be accomplished. The thin and relatively short capillary yields a small divergence of the injected beam with a half opening angle of 20°. The gas box is designed for pre-fill pressures of 10 mbar up to 100 bars and makes a flowrate accessible from 1018part/s up to 1023part/s. It hence is a versatile system for both diagnostic as well as fuelling applications. The implementation of this system in ASDEX Upgrade will be described and its application for line ratio spectroscopy on helium will be demonstrated on a selected example.
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: M
authors.identifier: 000000032953536X
authors.initials: M
authors.lastname: Griener
authors.affiliation: Department of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
authors.forename: O
authors.initials: O
authors.lastname: Schmitz
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Bald
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Bösser
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Cavedon
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: P
authors.initials: P
authors.lastname: De Marné
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Eich
authors.affiliation: Max Planck Institute for Plasma Physics, Wendelsteinstr. 1, 17491 Greifswald, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Fuchert
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Herrmann
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Kappatou
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Lunt
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Rohde
authors.affiliation: FZ Jülich, Institute for Energy- and Climate Research, 52428 Jülich, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Schweer
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Sochor
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: U
authors.initials: U
authors.lastname: Stroth
authors.affiliation: FZ Jülich, Institute for Energy- and Climate Research, 52428 Jülich, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Terra
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: E
authors.initials: E
authors.lastname: Wolfrum
authors.affiliation: Max Planck Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, GermanyPhysik Department E28, Technische Universität München, 85748 Garching, GermanyDepartment of Engineering Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706, USAMax Planck Institute for Plasma Physics, Wendelsteinstr. 1, 17491 Greifswald, GermanyFZ Jülich, Institute for Energy- and Climate Research, 52428 Jülich, Germany.