Fig. 10
From: In-situ monitoring of 3He/4He in summit gases of Kilauea Volcano (Hawaii) prior to the 2020 eruption
Histogram plot of measured power draw over elapsed time for the Helium Isotope Monitor (HIM) and Volcanic Gas Purification System (VGPS). The present programmed duty-cycle of ~ 4 h is shown. VQM = Vacuum Quality Monitor, an autoresonant ion trap mass spectrometer system; MKS = a customized high-resolution quadrupole mass spectrometer system