For pt. I see ibid., vol., 31, no. 8, p. 1525-32 (1995). The plasma temperatures in microwave discharged CO/sub 2/-N/sub 2/-He laser gas mixtures were examined using the spectroscopic and electrostatic probe methods. A vibration temperature of N/sub 2/ molecules, obtained spectroscopically, was determined to be nearly 7000 K without gas circulation and to be nearly 4000 K at the mass flow rate of 4.2 kg/h. It is found that an efficiency of laser output power exceed 14% (RF to laser output power conversion ratio) below the vibration temperature of 4000 K. The values of vibration temperature obtained were higher than those reported in DC discharges.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">></ETX>