Other mobile ground based platforms may use the same system, but fixed mounted weapons can be connected directly to the power grid (if it is big enough) and may fire by standard electrical means.
Most lasers fire by means of an electrical flash tube, the light from which is then focused using various means, including CO2 or Xenon gas, artificial ruby rods, etc and then focused thru lenses to emit out one end of the device.
I am almost positive you are confusing two seperate programs- The THEL, and the Airborne Laser (ABL) The ABL is still under development, completely seperately from the THEL.
"Most lasers fire by means of an electrical flash tube, the light from which is then focused using various means, including CO2 or Xenon gas, artificial ruby rods, etc and then focused thru lenses to emit out one end of the device."
I think these lasers work on a completely different principle: here's a quote from an Air Force laser program:
An excited state of molecular oxygen, O2(1D ), is generated by the chemical reaction between chlorine gas and an aqueous mixture of hydrogen peroxide and potassium hydroxide (basic hydrogen peroxide). The byproducts of this reaction include salt (potassium chloride) and heat. Water vapor in the gas flow is removed because it interferes with the laser gas kinetics. Molecular iodine is then injected and mixed with the gas flow, and some of the energy in the oxygen is used to dissociate the iodine. Resonant energy transfer from the excited oxygen to the atomic iodine excites the iodine, and the gas flow is accelerated to a supersonic velocity in an expansion nozzle to create the laser gain region. Light is extracted with a laser cavity positioned transverse to the gas flow, and the exhaust gases are scrubbed to remove the residual chlorine and iodine.
Anyway, they will all help us be a "bright and shining light" to our foes *grin*