Bochum 2015 – scientific programme
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P: Fachverband Plasmaphysik
P 16: Poster Session - Helmholtz Graduate School for Plasma Physics
P 16.2: Poster
Tuesday, March 3, 2015, 16:30–18:30, Foyer Audimax
High Speed Gas Valve for Massive Gas Injection in Tokamaks — •Mathias Dibon1,2, Albrecht Herrmann1, Klaus Mank1, Vitus Mertens1, Rudolf Neu1,2, Gabriella Pautasso1, and Bernhard Ploeckl1 — 1Max-Planck-Institut für Plasmaphysik, Boltzmannstr. 2, 85748 Garching, Germany — 2Technische Universität München, Boltzmannstr. 15, 85748 Garching, Germany
For the purpose of mitigating the forces on the vessel during disruptions, a system for massive gas injection is used at the tokamak ASDEX Upgrade. Three gas valves are mounted inside the vacuum vessel with a distance of 10 cm between the nozzle exit (diameter 14 mm) and the plasma edge. This requires the valves to be insensitive to strong magnetic fields, especially on the magnetic high field side, to high temperatures and ionizing radiation. The new High Speed Gas Valve is meant to replace an old electromagnetic valve in order to increase the gas delivery efficiency and the operational reliability. The valve is closed by compressed air (20 bar) acting on through a piston on the stem and valve plate, pushing the seal onto the sealing edge and closing the gas chamber. Piezoelectric clamps secure the stem while the 80 cm3 gas chamber is filled with neon or argon at a pressure of up to 50 bar. The valve opens up when the piezoelectric actuators release the stem and a stack of disk springs accelerates the valve plate until it reaches its maximum stroke of 4,5 mm after 4 ms. This allows a mass flow rate of the gas up to 105 Pa*m3/s. A characterisation of the valve will be presented in the contribution.