A new disruption mitigation valve (DMV) and gas flow in guiding tubes of different diameter

作者：Finken K H^*; Lehnen M; Bozhenkov S A

来源：Nuclear Fusion, 2011, 51(3): 033007.

DOI：10.1088/0029-5515/51/3/033007

A new disruption mitigation valve, the DMV-30, has been developed and tested. The orifice output area of the valve is a factor of 2.4 and 12.25 times larger than that of its predecessors, DMV-20 and DMV-10, and the gas reservoir amounts to 1.3 L while the older version used at JET had only 0.65 L. The coil which provides the magnetic field pulse for the activation of the piston by an eddy current is outside of the working gas volume such that all gas volumes are now made of stainless steel. The valve has the advantages of the previous developments: it is robust and reproducible, opens fully within 3ms and releases 50% of the gas within about 5ms (He) to 10 ms (Ar). The valve is attached subsequently to two different guiding tubes, one with an inner diameter of 38mm as used presently at JET and one with 102mm inner diameter; the aim of this paper is the analysis of the gas flows for different diameters. The front of the gas pulse propagates with a Mach number of about 2.5 through the tubes, independent of the two diameters. This high speed agrees with theoretical expectations of flow expansion of a half infinite tube in vacuum. In the quasi-stationary phase of the expansion, the gas flows with about sound speed in the 102mm tube and with about half of the sound speed in the 38mm tube.

• 出版日期2011-3