New Scientist: Sweeping stun guns to target crowds

Weapons that can incapacitate crowds of people by sweeping a lightning-like beam of electricity across them are being readied for sale to military and police forces in the US and Europe.
At present, commercial stun guns target one person at a time, and work only at close quarters. The new breed of non-lethal weapons can be used on many people at once and operate over far greater distances. . . .
Engineers working for the US Department of Defense's research division, DARPA, and defence companies in Europe have been working out how to create an electrically conductive path between a gun and a target without using wires.
[Sic] Xtreme Alternative Defense Systems (XADS), based in Anderson, Indiana, will be one of the first companies to market [a] type of wireless weapon. [Sic] the $9000 Close Quarters Shock Rifle projects an ionised gas, or plasma, towards the target, producing a conducting channel. It will also interfere with electronic ignition systems and stop vehicles.
"We will be able to fire a stream of electricity like water out of a hose at one or many targets in a single sweep," claims XADS president Peter Bitar. . . .
XADS is also planning a more advanced weapon which it hopes will have a range of 100 metres or more. Instead of firing ionised gas, it will probably use a powerful laser to ionise the air itself. The idea has been around for decades, says LaVerne Schlie, a laser expert at the US Air Force Research Lab in Kirtland, New Mexico. It has only become practical with advances in high-power solid-state lasers.
"Before, it took a laser about the size of two trucks," says Schlie. "Now we can do it with something that fits on a tabletop."
The laser pulse must be very intense, but can be brief. So the makers of the weapons plan to use a UV laser to fire a 5-joule pulse lasting just 0.4 picoseconds - equating to a momentary power of more than 10 million megawatts.
This intense pulse - which is said not to harm the eyes - ionises the air, producing long, thread-like filaments of glowing plasma that can be sustained by repeating the pulse every few milliseconds. This plasma channel is then used to deliver a shock to the victims similar to a Taser's 50,000-volt, 26-watt shock."