OK, dumb questions - the H202 is entering the combustion chamber at what pressure? below chamber pressure,with a valve, like a pulsejet? or is there a turbopump

OK, dumb questions - the H202 is entering the combustion chamber at what pressure? below chamber pressure,with a valve, like a pulsejet? or is there a turbopump somewhere? and what powers it? I'm guessing centripetal force once the rotors are spinning helps (but isn't there a potential evil feedback loop hiding in there somewhere?)