A method/apparatus may comprise operating a line narrowed pulsed excimer or molecular fluorine gas discharge laser system by using a seed laser oscillator to produce an output which may comprise a first gas discharge excimer or molecular fluorine laser chamber; a line narrowing module; a laser amplification stage which may comprise a ring power amplification stage; the method of operation may the steps of: selecting a differential timing between an electrical discharge between a pair of electrodes in the first laser chamber and in the second laser chamber which at the same time keeps ASE below a selected limit and the pulse energy of the laser system output light beam of pulses essentially constant.