America's top-secret elite commando forces have been field-testing a "plasma knife" - a handheld unit which generates a cutting "blade" of glowing ions.
Disappointingly for any wouldbe kimono-clad combat mystics out there, the handheld energy cutlass isn't intended for hand to hand combat and can't be used for parrying directed-energy-weapons fire. Rather, it's a surgical tool - intended to let combat medics cut into stricken buddies without worrying about bleeding, as the plasma blade seals off blood vessels as it slices through flesh.
Handheld plasma scalpels are already in use by normal hospital doctors, and manufacturers claim that they offer an ideal middle way between a normal steel blade and "electrosurgery" techniques. With steel you get too much bleeding: with an electric cutter, which cauterises as it goes, there's too much burning and scarring. One medical-equipment firm claims (pdf) that its plasma rigs reduce bleeding by 60 per cent compared to an ordinary knife, yet cause 75 per cent less "thermal damage" than an electrocutter. Better still, apparently one needs "66 per cent less force to cut tissue", and there is "little to no surgical smoke in the cut mode".
From the point of view of the Special Operations Command (SOCOM, the US forces' secretive supertroopers), there are some downsides to a normal plasma knife. While the unit itself is handily pen-sized, it has to be powered via cables from a bulky cart-mounted machine which requires a power socket. This isn't ideal for a surgeon operating in the snows of the Hindu Kush or the burning deserts of Helmand, far from friendly support.
Hence it seems that SOCOM has developed a "wearable, low-power" plasma cutter, presumably with a belt or harness mounted powerpack for use in the field. According to this government pdf, unearthed by the team at Wired magazine's Danger Room blog, "field evaluation" of the portable energy blade was completed at some point during the 2008 financial year. (So, worryingly, were "studies" into treating decompression sickness in divers by injecting refrigerator coolant into their veins.)
It would seem that American combat medics of the future, in addition to their spraycan wound-Polyfilla, ultrasonic blood-stifler cuffs and in-uniform drawstring tourniquets, may soon be deploying pocket lightsabres in the battle to bring their battle-stricken buddies back alive. ®