How to tell if light is damaging plant?

The Ts600 is only a 100W designed for a small space, if you want to check how far you can distance your lamp from the plant try lowering the lamp to as low as 8-10 inches (seems like you're in flowering so I'd try going with 8) and check you plant regularly, if she shows signs of radiation/light stress (foliage starts to fold and curl upwards starting from the top of the plant) then move the light 2 inches higher! Also don't forget that in flowering the plant needs more light to produce fatter and denser buds! *I started using the TS600 as extra lighting during flowering, I got it set 5 inches from my plants and they're doing completely fine! it all depends on the plant and what stage of growth she is in. Hope this helps! Good luck and happy growing :)