Performance characteristics of a TEA double-discharge grid amplifier

A novel discharge circuit for the pulsed excitation of a double-discharge grid-cathode TEA-CO
2
amplifier is described. A distinctive feature of this circuit is the use of an underdamped preionizing discharge, together with a slow rate of electrical energy injection in the amplifying medium. Significant improvements in the stability and uniformity of the discharge is obtained by increasing the pumping period to the
2-6 \mu
s range. Small-signal gain coefficients up to 0.035 cm
^-1
are achieved in a
5 \times 5 \times 50
cm
³
discharge volume with an electrical input energy density as low as 120 J/l. Details concerning the design and operation of the circuit are given. The temporal dependence of the gain upon circuit parameters, gas mixture composition, and electrical energy input is studied, and an investigation is made of the spatial gain distribution and optical homogeneity over the amplifier cross section. Measurements of the gain-saturation characteristics with a 2-μs probing pulse indicate a value of
5.8 \times 10^{-20}
cm
²
for the stimulated emission cross section.