Two-stage TEA(transversely excited atmospheric pressure) $CO_2$ laser amplifier system, AMP I and AMP II are constructed and their amplification characteristics are investigated theoretically and experimentally.
Multiple-wire corona preionization method is used for uniform discharge in laser oscillator and amplifiers. At optimum gas ratio, $CO_2:N_2:He= 1:1:3$, output pulse energy of the oscillator is 0.4J and after propagating AMP I, pulse energy is amplified to 1J, finally two-stage amplification gives the laser pulse energy of 1.5J which is lager than pumping threshold of para-$H_2$ Raman laser.
The rate equations of the amplifiers are solved numerically, and the results are compared with the experimental results. In conclusion, the small signal gain coefficient of AMP I is 0.025/cm and that of AMP II is 0.02/cm.
