title: Spring-driven high speed valve for massive gas injection in tokamaks.
abstract: A new high speed gas valve was developed for disruption mitigation studies in the tokamak ASDEX Upgrade. The valve was designed to operate inside the vacuum vessel to reduce the time of flight of the injected gas and to prevent dispersion of the gas cloud before the gas reaches the plasma. A spring-driven mechanism was chosen for the valve as it is robust against the high magnetic fields and electromagnetic disturbances inside the vessel. The internal gas reservoir (128 cm3) of the valve, which holds the mitigation gas, is opened within 1.5 ms, and the maximal stroke between the valve plate and nozzle (diameter 13 mm) is 4.5 mm. This allows a peak flow rate of 72 kPam3/s after 1 ms which was determined both analytically and numerically. The highest gas velocity (approximately 560 m/s) is reached 0.6 ms after the valve is opened. The gas cloud expands in a pear shape with an opening angle of 49°.
authors.affiliation: Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: M
authors.identifier: 0000000326946956
authors.initials: M
authors.lastname: Dibon
authors.affiliation: Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Mank
authors.affiliation: Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: G
authors.initials: G
authors.lastname: Pautasso
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: 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: V
authors.initials: V
authors.lastname: Mertens
authors.affiliation: Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: R
authors.identifier: 0000000260621955
authors.initials: R
authors.lastname: Neu
authors.affiliation: Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Ploeckl
authors.affiliation: Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, 85748 Garching, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Rohde