Design and construction of a high repetition rate low average power TEA CO2 laser with ultra violet pre ionization is presented. Replacing thyratron with a high voltage semiconductor switch and magnetic pulse compressor considering the highest peak power achievable is investigated. When using semiconductors as main switch of laser excitation circuit the output energy and laser power is lower about 5-10% relative to thyratron excitation circuit but the sealed off operation of laser is more uniform.Thyratron based excitation circuit Semiconductor based excitation circuit