A small photoswitched TEA CO2 laser has been developed. This small aperture, low repetition rate laser can produce 69 mJ optical pulses from a discharge volume of 12.5 cm3, with an energy efficiency of 11.1%. This energy efficiency is the highest so far reported with such lasers. Corona UV sources driven by a simple inexpensive solid state exciter are used to trigger the discharge. Also demonstrated is the wider input energy loading and enhanced discharge stability provided by overvolting the laser head.