The only reason I have enough of these is because I played the loot cave back when that was a thing. Now there's no good way to get this stuff and even my supplies are almost completely depleted. Just this week I finally ran out of weapon parts. but I still have several hundred hadronic essence (down to ~300 from the ~800 I once had). My titan and hunter however are completely starved for armor parts and only get upgraded when absolutely necessary.