MR4.1 update: After 20 hours at 100 watts, pressure continued to increase, though at a slower rate. RGA sampling showed that all free D2 had gone into reduction of oxides and carbonate, leaving predominantly CO2 (mass 44) and D2O (detected as OD+, mass 18). Traces of N2 (mass 28) and O (mass 16) also appeared.
One consequence of this process is shown by the core temperature remaining 10°C cooler than the cell body, due to the lower thermal conductivity of the product gases. In prior calibrations with 300 Pa of D2 but without meshes, those temperatures stayed typically within 1°C at equilibrium
The cell will now be pumped out while still hot, then allowed to cool before adding fresh D2 for MR4.2.