In a rotating mirrorQhyphen;switching scheme under suitable experimental conditions an effect termed lsquo;lsquo;mode sweepingrsquo;rsquo; can play an important role in the buildup of the laser pulse. A theoretical model has been developed which takes into account this effect and also considers the nonuniform gain distribution resulting from the helical arrangement of the discharge pins. A number of approximations simplify the computation. The agreement between theory and experiment is excellent. The basic limitation of the theory is discussed. The discrepancies between theory and experiment can be attributed to the neglect of the lsquo;lsquo;thermal lensingrsquo;rsquo; in the gas medium, that normally occur in such discharges.
展开▼