sentences:  The pulse is then sent into the amplifiers as normal.When it exits the beamlines it is recombined in a similar set of gratings to produce a single very short pulse, but because the pulse now has very high power, the gratings have to be large (approx 1 m) and sit in a vacuum.Additionally the individual beams must be lower in power overall; the compression side of the system uses 40 beamlines of about 5 kJ each to generate a total of 200 kJ, whereas the ignition side requires 24 beamlines of just under 3 kJ to generate a total of 70 kJ.