| Summary: | 博士 === 國立清華大學 === 電機工程學系 === 89 === Abstract
Electrical discharge is a common method for the excitation of a gas laser. The RF excitation especially has outstanding performance for uniform discharge. The discharge tube has the characteristic of capacitive loading due to the property of the ion sheath. Without the existence of the ballast resistor, the discharge can still be maintained stably and efficiently. The RF excitation accommodates more input power level than the DC discharge. The operating pressure of the gas can be raised and the laser power will be increased accordingly. With the superior performance mentioned above, the RF excitation still has many advantages such as the lower firing voltage, the electrodeless operation to avoid the sputtering pollution and so on.
The standing wave effect in the RF excitation causes the voltage to distribute nonuniformly along the longitudinal electrodes. Segmented excitation can improve the uniformity of the discharge and enhance the laser efficiency. The segmented discharge used in our experiments has the advantages such as uniform discharge, easy power transform to the load, less ohm loss in matching circuit. Reliable components and compact elements make the entire setup more efficient and lower coat.
The large area discharge (area-scaling) and the arrayed structure (volume-scaling) have been developed to increase the laser power per unit length. The characteristics of multi-segment RF-excited CO2 slab waveguide and its array lasers with effects of additional xenon gas have been investigated in this thesis. The laser efficiency of 20.5% with 10% xenon is obtained in multi-segmented slab waveguide laser. And in the segmented coupled slab waveguide array, the efficiency is 19.5% with 10% xenon. The efficiency of our segmented structures is superior to the others. The segmented laser structure has shown to be suitable for the RF excitation of CO2 and other gas lasers.
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