2026 年 21 巻 論文ID: 1202033
A non-evaporable getter (NEG) pump was experimentally installed in the QUEST spherical tokamak to enhance particle exhaust capability during long-pulse, high wall temperature operation (473 K). Activation and pumping performance tests were conducted using hydrogen gas injection and quadrupole mass spectrometry. During activation at 773 K, hydrogen desorption was clearly observed, whereas impurity species (mass number 18, 28, 32, 44) desorption remained strongly suppressed. Pumping tests at 473 K demonstrated hydrogen-selective exhaust with an effective pumping speed of approximately 150 L/s. These results demonstrate that NEG pumps can provide a controllable and impurity-compatible particle exhaust method in fusion-relevant environments. In particular, the suppression of impurity release during activation suggests the possibility of in situ regeneration without significant degradation of plasma conditions due to impurity contamination, enabling continuous operation without isolation. This operational flexibility highlights the potential of NEG pumps as assist tools for particle control in steady-state plasma operation.
