step down 200W SMPS

[Nicx]

hi, ive trying to construct a buck converter outputting 24V and 10A max. the minimum output power i can settle for is around 150 Watts. im attaching a schematic. i hope someone would help me.

ive tried testing it with a constant voltage test of an e-load. it seems that the current load capability of my circuit is almost the same as the current drawn from the DC supply. im temporarily using a desktop DC power supply with a max of 30V-3A output. since my circuit behaves this way, the maximum power i get is just 72Watts. i was advised to place 2 of these DC power supplies in series to achieve the 60V max input and an input power of 180Watts. i tried this but fried up my circuit in doing so. can anyone suggest how i should debug this? thanks.

my inductor has an iron power core. material -26. and a current value of 39uH.