Greifswald 2024 – wissenschaftliches Programm
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P: Fachverband Plasmaphysik
P 15: HEPP V
P 15.2: Vortrag
Mittwoch, 28. Februar 2024, 14:30–14:55, ELP 6: HS 3
Effect of the newly installed cryo-vacuum pump on neutral gas pressures and particle exhaust — •Victoria Haak, Chandra Prakash Dhard, Thierry Kremeyer, Dirk Naujoks, Georg Schlisio, and W7-X Team — Max-Planck-Institut für Plasmaphysik, Greifswald, Germany
Gas exhaust is a key requirement for density control in a fusion device and, apart from the pumping speed and the subdivertor geometry, strongly dependent on the neutral gas pressure in the subdivertor and in front of the pumps. In each of the ten island divertor modules in Wendelstein 7-X, a cryo-vacuum pump (CVP) has been installed for the last campaign (OP2.1) to improve the particle exhaust capabilities. During dedicated gas injection tests, the pumping speed of the CVPs has been determined for hydrogen (70 m3/s), nitrogen (21 m3/s), neon (22 m3/s) and argon (9 m3/s). No significant differences in the neutral gas pressures in the subdivertor have been observed in discharges with and without CVPs in operation. Overall, neutral gas pressures on the order of few times 10−4 mbar were measured in the subdivertor region, which still corresponds to the molecular flow regime in which the effect of the cryo-vacuum pump on particle exhaust is limited.
Keywords: cryo-vacuum pump; neutral gas pressures; particle exhaust