Studies of breakdown threshold intensity for air at various pressures in the range of 24–760 torr using 0.355, 0.532 and 1.06 µm radiation are reported. We observep^−0.8 scaling ofI_th at 1.06 µm and a weak scaling ofp^−0.4 at 0.532 and 0.355 µm radiation. Strong dependence of breakdown spot size on laser power but weak dependence on air pressure is observed.

We report laser oscillations in Cd II on 4d⁹5s²²D_5/2 − 4d¹⁰5p²P_3/2 transition at 441.6 nm using laser produced tungsten plasma as a pumping source. Mach Zehnder interferometer is used to measure electron density. Design and working of the crossed heat pipe used in the studies is discussed.