دریچه پیزو محور برای مطالعه کاهش تداخل در توکاماکی

Disruptions are a major issue for the safe operation of tokamaks. Hence the mitigation of disruptive effects is of high priority in view of ITER and DEMO. Previous experiments at ASDEX Upgrade have shown that the injections of massive amounts of gaseous impurities using in-vessel valves mitigate disruptions very efficiently, due to short time of flight of the gas towards the plasma edge and the applicability of pure noble gases. A new valve concept for in-vessel massive gas injection has been developed at ASDEX Upgrade to replace the old valves which suffered from reliability problems. This new valve is a normally closed valve since the valve plate is pressed into the main sealing by a stainless steel bellow (acting as a spring), sealing off the gas reservoir, which can hold 42 cm3 of gas at a pressure of up to 5 MPa. The valves actuator consists of 4 piezoelectric stacks which are mounted in two parallel pairs into a monolithic titanium frame. This frame is rigidly connected to the valve plate and it amplifies the stroke of the stacks to allow a total stroke of the valve plate of 2.2 mm, which is reached after 5 ms. The diameter of the straight valve nozzle is 14 mm allowing a peak flow rate of 44 kPam3/s after 1 ms. The valve has a size of 173 mm × 88 mm × 70 mm.