If we can get petawatt picosecond lasers that shoot 75 million times per second then we will have laser fusion space propulsion with an ISP of 900,000
There is a 55 review from 2012 of the current status of high energy laser systems.
If the fiber lasers could shoot 1000 times more frequently then we would the fusion space propulsion system.
High repetition high energy lasers for commercial power generation would need even more power to generated. Although a certain level of joule production from the laser pulses could produce high levels of fusion energy if the fused material produces a high level of energy gain (say 1000 times or 10000 times.) Then the number of pulses per second times the joules of a pulse times the energy gain needs to get to say 10 million or 100 million joules for one second.
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