Hannover 2016 – scientific programme
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P: Fachverband Plasmaphysik
P 5: Poster Session- Helmholtz Graduate School for Plasma Physics
P 5.4: Poster
Monday, February 29, 2016, 16:30–19:00, Empore Lichthof
Piezoelectric Valve for Massive Gas Injection in ASDEX Upgrade — •Mathias Dibon1,2, Albrecht Herrmann1, Klaus Mank1, Vitus Mertens1, Rudolf Neu1,2, Gabriella Pautasso1, and Bernhard Ploeckl1 — 1Max-Planck-Institute for Plasmaphysics, Boltzmannstr. 2, 85748 Garching, Germany — 2Technical University Munich, Boltzmannstr. 15, 85748 Garching, Germany
A sudden loss of plasma temperature can cause a disruption, which poses a significant problem for current Tokamaks and future fusion devices. Hence, mitigating forces and thermal loads during disruptions is important for the integrity of the vessel and first wall components. Therefore, high speed gas valves are used to deliver a pulse of noble gas onto the plasma, which irradiates the thermal energy quickly, avoiding localized heat loads and mechanical stress due to induced currents. A new design for such a valve is currently under development. The valve plate is driven by two piezoelectric stack actuators. The stroke of the actuators (0.07 mm) is amplified by a monolithic titanium frame and reaches 2 mm. The frame also serves as spring to pre-load the actuators. In the idle state, it also presses the conical valve plate into the seal, closing the gas chamber (42 cm3). The actuators accelerate the stem and the valve plate until it is fully opened after 2 ms. The orifice of the valve has a diameter of 14 mm. This allows a peak mass flow rate of the gas up to 8*104 Pa*m*/s after 1.8 ms and an average mass flow rate of 2*104 Pa*m*/s over the evacuation time of 10 ms. Therefore, one valve would be sufficient to deliver the required amount of gas to mitigate disruptions at ASDEX Upgrade.