Comparison of modified driver circuit and capacitor-transfer circuit in longitudinally excited N2 laser

We developed a modified driver circuit composed of a capacitance and a spark gap, called a direct-drive circuit, for a longitudinally excited gas laser. The direct-drive circuit uses a large discharge impedance caused by a long discharge length of the longitudinal excitation scheme and eliminates the buffer capacitance used in the traditional capacitor-transfer circuit. We compared the direct-drive circuit and the capacitor-transfer circuit in a longitudinally excited N2 laser (wavelength: 337 nm). Producing high output energy with the capacitor-transfer circuit requires a large storage capacitance and a discharge tube with optimum dimensions (an inner diameter of 4 mm and a length of 10 cm in this work); in contrast, the direct-drive circuit requires a high breakdown voltage, achieved with a small storage capacitance and a large discharge tube. Additionally, for the same input energy of 792 mJ, the maximum output energy of the capacitor-transfer circuit was 174.2 μJ, and that of the direct-drive circuit was 344.7 μJ.