sentences:  It is not clear how quickly the electrons stop in the fuel load; while this is known for matter under normal pressures, it's not for the ultra-dense conditions of the compressed fuel.To work efficiently, the electrons should stop in as short a distance as possible, to release their energy into a small spot and thus raise the temperature (energy per unit volume) as high as possible.How to get the laser light onto that spot is also a matter for further research.