Pallavi Raote

Switching of a TEA CO 2 laser with its own UV emitting parallel spark channels

The efficient operation of a TEA CO(2) laser wherein the parallel spark channel preioniser of the laser itself functioned as a switch is reported. Simultaneous closure of the parallel gaps without an external switch has been achieved by ballasting them with mutually coupled inductances. The repetitive operation capability of such a laser is also discussed.

Study of laser assisted decontamination of commonly used clad surfaces

The decontamination factor, defined as the ratio of initial to residual activity, is studied as a function of laser fluence for three kinds of clad surfaces viz., plain zircaloy, autoclaved zircaloy, and stainless steel with cesium as the simulated contamination. It has been found that the decontamination factor exhibits a maximal behavior with the laser fluence and its maximum value occurs at different laser fluences in the three cases. The maximal behavior is attributed to reduced coupling of energy from the laser beam to the substrate due to the initiation of surface-assisted optical breakdown. The results obtained in the experiment carried out in helium environment qualitatively support this explanation.

Switch-less operation of a TEA CO2 laser.

We report here the operation of a UV pre-ionised mini-TEA CO2 laser where the use of an external switch has been dispensed with. This was rendered possible by making the preioniser spark array play a dual role- that of a switch as well as of a source of UV photons that pre-conditioned the inter-electrode volume.

Simultaneous closure of multiple high voltage parallel spark channels without switch: A parametric study

Results of a detailed parametric study of a self-switched mutually inductively coupled high voltage parallel spark preionizer are presented. The maximal behavior exhibited by the breakdown voltage of the parallel gaps with respect to the number of mutually coupled turns has been explained. It has been found that there exists a threshold rise time of the current pulse beyond which simultaneous closure of the parallel gaps is not possible and that this threshold value is independent of the nature and geometry of the cores used for the mutual coupling. The degree of simultaneity of the closure of the self-switched parallel gaps matched that of the conventional operation of such gaps.