I attended a presentation by the NIF guys earlier this year at a conference, where IIRC one of the bigger challenges was the optics.
Due to the amount of energy being put through them (particularly since it was pulsed), any imperfections would be amplified, quickly rendering the component unusable. They ended up developing an entire automated system for fixing these using an approach I can't recall.
So I guess the losses in terms of reaching break even (which this facility is not specifically aiming for, its main purpose is to ensure our hydrogen bombs still work) are the electricity-to-laser efficiency (IIRC these lasers are pretty old now and less efficient than modern lasers), making optics which can better tolerate the energy, getting the timing right so that the pellet is compressed equally (any imbalances manifest as reduced efficiency) and making better pellets (since of course, this is also an energy intensive process at the moment).
Due to the amount of energy being put through them (particularly since it was pulsed), any imperfections would be amplified, quickly rendering the component unusable. They ended up developing an entire automated system for fixing these using an approach I can't recall.
So I guess the losses in terms of reaching break even (which this facility is not specifically aiming for, its main purpose is to ensure our hydrogen bombs still work) are the electricity-to-laser efficiency (IIRC these lasers are pretty old now and less efficient than modern lasers), making optics which can better tolerate the energy, getting the timing right so that the pellet is compressed equally (any imbalances manifest as reduced efficiency) and making better pellets (since of course, this is also an energy intensive process at the moment).