In a vacuum chamber, a thick slab is placed under an array of laser diodes with an output...

In a vacuum chamber, a thick slab is placed under an array of laser diodes with an output constant pulse M thermocouple is inserted inside the slab at 25 mm from the surface and the slab has an initial uniform temperature of20°C. The known properties of the slab are k = 63.9 W/m·K and α = 18.8 × 10-6 m2 /s. If the thermocouple measured temperature of 130°C after 30 s the slab surface has been exposed to the laser pulse, determine (a) the amount of J energy per unit surface area directed on the slab surface and (b) the thermocouple reading after 60 s has elapsed

FIGURE P 18-78