hydrogen fusion that self sustaining is imposible but noble is posible and also i will recomend u use deuterium as first fuel and ignite it with neutrons and after electrons for get instantly hot hydrogen and pressure and also if u mean infinite fusion then u may try somehow make protons be extremly fast and create hydrogen noble or sing 
but if u preheat hydrogen and make alot of insulation from ambient air and after fusion it may work

but u may create 2 core fusion reactor where 1 core is for heat and core 2 is for fusion up to oxygen-bmtl

this all because fusion is nerfed and heat that it creates is not enough for fusion so it is technicaly imposible to create self sustained fusion

i was trying to create self sustained fusion result from 1900 and a bit heat it goes to 2300 result it is extreme useless because noble fusion needs more heat so result it is imposible do noble fusion instead but better use deuterium electrons and neutrons

@username90000 (View Post)

 one of my recent projects proved that wrong. by controlling hydrogen releasing, and using bizarre, you could in fact, make sustainable hydrogen fusion that will sustain the heat and pressure, and in my testing, the furnace temperature went from the initial 9000C to 9500C. my proj id (not advertising just showing example): https://powdertoy.co.uk/Browse/View.html?ID=2934334

How about using countercurrent heat exchangers? They can easily heat up the hydrogen while cooling the NBLE down to only a few hundred degrees, and you can find some in those ultra-cool refrigerator designs.