Capacitor modification to the Schenck and Metcalf N2 laser

After a short period of satisfactory operation, the output of the N2 laser developed by Schenck and Metcalf (1973) was found to be about 40% of the expected power. This reduction in laser output was caused by failure (or deterioration) of a number of the 500-pF doorknob dumping capacitors. The capacitors described in the present paper were developed to overcome this problem. They are of a simple double-sided parallel plate design. The length of the N2 laser allows the large area capacitors to be incorporated easily into the laser structure. The capacitors were constructed with 12 x 40 cm plates composed of 0.02-inch Mylar plastic sheets sandwiched between 0.71-mm copper plates. Their capacitances were roughly 3 nF each. The Mylar dielectric has a breakdown rating of 2 kV/mil and a measured dielectric constant of 1.8. These dumping capacitors increased the output pulse energy from 0.5 mJ to 1.1 mJ, corresponding to a peak power of 110 kW in a 10-nsec pulse. Operation over a period of four months showed no detectable power decrease.