A 15×15 cm cross section, 50 cm long, TEA CO2amplifier using a reliable and simple discharge system is described. This system permits external control of the width of the discharge and is easily scalable. The spatial distribution of the small signal gain over the cross section of the amplifier is investigated. An average small signal gain coefficient of 0.022 cm−1is obtained at an input energy density of 100 J/liter. Measurement of the saturated energy gain is reported. The small signal gain has also been measured on a smaller cross section but more heavily excited amplifier, using a similar discharge system.