ijuin wrote:A "steam explosion" would be certain destruction to the body parts that it affected, but it might take more energy overall than simply burning open some major blood vessels and letting him bleed to death, since you have to flash-boil several grams (possibly a dozen or more grams) of water, which takes about three kilojoules per gram of water (slightly more in the body than in free air because the surrounding flesh can endure 20-30 kPa of internal gas pressure before anything seriously ruptures).
According to Dr. John Schilling, a laser weapon would need about one kilojoule to incapacitate a human target, divided into 1 joule pulses at 5 microsecond intervals. This will make a tunnel about 30 cm long in soft tissue, 15 cm in bone or plastic, 5 cm in brick or concrete, and 2.5 cm in steel or ceramic. 5 microsecond pulses is optimal for soft tissue, other materials need different intervals. It will be difficult to make the tunnel longer than 30 cm in soft tissue.
Pulse #1 hits the hapless target's skin. It makes a hole 1 mm in diameter, but steam expansion will widen it to up to 4 cm. The 5 microsecond delay is to allow the steam and tissue debris to clear the beam path, otherwise beam power is wasted and penetration suffers. Pulse #2 hits the bottom
of the 4 cm crater and makes a new crater. Rinse, lather, repeat. Past about 30 cm, enough time has elapsed for the entire tunnel to collapse.
Go to the Atomic Rocket website under Sidearms Energy for details. I would post the link but it keeps marking my message as spam.