&"Did you make an isotopic analysis of the gas to see the relative proportions of He3 and He4? I suppose it could be done with a spectral analysis of the gas?"
Yes, with a quadrupole spectrometer with excellent low amu separation. The reactor was loaded with nanoscale NiO on Al2O3 substrate. Hydrogen fusion initiated at 830 C. and destroyed the reactor. I was able to measure an increase in helium before runaway destruction. This was many years ago and probably the first reactor produced hydrogen fusion reaction. It was simply a proton transmutation. This nickelous oxide array produces amazing results.
Longview I may be getting redundant on my posts' at 90 years old my recollection is becoming a problem. Accuracy is still ok.