Power dissipation in a capacitive coupled 450 khz discharge set up for a CO$_{2}$ laser

Abstract

In order to find the power dissipation in a 450 kHz capacitive coupled CO$_2 $ laser system using a 50 $\Omega$ $\pi $ matching network, we investigate its electrical behavior. Current and voltage evolution and the phase delay in all the circuit elements were measured with calibrated Rogowski coils and high voltage probes. The signals were registered using a digital oscilloscope interfaced to a PC. When the supplied power lay between 0.5 and 1 kW, the signals had a non-distorted sinusoidal form. This allowed to make the power dissipation estimation in the circuit elements using their current and voltage peak values, and their phase delay. Phase measurements were made with $\pm $ 0.3$^{\circ}$ accuracy, which gives an accuracy of $\pm $ 1.5% in the laser chamber power dissipation estimation. The laser chamber power dissipation is estimated at between 30 and 50% of the supplied power, and the rest is consumed in the matching circuit. The power losses in the matching circuit greatly contribute to the poor total system efficiency ($\approx$ 0.8%). The estimated resistance and capacitance values of the laser chamber are also presented.