Destructive EMP Devices

I think I did once see an idea for a real-life phasor, using (I think) a laser to ionise the air, with a high voltage generator (Marx? Cockcroft-Walton?) to provide the "spark" to travel down the ionised path.

My thought at the time was "the laser would probably do the most damage to the object at the far end".

There's even a Wikipedia entry