THE TIME EVOLUTION OF THE RESISTANCES AND INDUCTANCES OF THE DISCHARGES IN A PULSED GAS-LASER THROUGH ITS CURRENT WAVE-FORMS

In the present work, the time-dependent resistances and inductances of the electric discharges in a pulsed gas laser are revealed through th e current waveforms of the circuit. This can be achieved combining ste p-by-step the experimental current waveforms with the current differen tial equations of the system. Thus, digitizing the signal, the derivat ive is calculated through a computer, For a certain time instant, subs tituting the values of the current and its derivative into the integro differential equations describing the performance of the circuit loops , we form relationships which connect the values of the resistance and inductance for this particular time instant. Combining relationships originating from very close adjacent time instants, the values of the resistances and inductances can be found. Scanning the entire time reg ion of the discharges, the time dependence of the resistances and indu ctances of the discharges are revealed. Their behavior shows an abrupt drop for the resistances and a sharp peak for the inductances, both d uring the ''formation phase.'' After that, the above characteristic qu antities fluctuate slowly around constant values. The sharp drop of th e resistances was expected, bearing in mind that the number of the cha rges increases dramatically through the electron avalanche multiplicat ion during the first few nanoseconds, causing the abrupt reduction of the resistances. On the other hand, the sharp peak of the inductances was unexpected. A plausible explanation for this phenomenon is that th e plasma undergoes a temporary constriction which is due to the predom inant attractive magnetic forces during the ''formation phase'' of the discharge.