Application of Machine learning in modelling experimental system as a PhD topic
It's very unlikely that anybody here has the expertise needed to assess the validity of a PhD topic, especially about a highly specialized (and unspecified) experimental system. You should discuss this with your potential academic supervisor, and I'd suggest you try to find a co-supervisor or collaborator expert in DL as well.

In general for a decent PhD topic you would need to make sure that it hasn't been done before and that there are reasonable grounds to think it's feasible. Study the state of the art and find out if anything similar has been published:


If something very close already exists, it might be too trivial
If there's nothing even remotely close to it, it's probably not feasible or very hard.


Good luck!