Identify What Prgram Is Doing a Lot of Disk Activity

I have a laptop that, after boot up is completed, continues to do a lot
of disk activity for fifteen minutes or more. This is a laptop I will
use on a plane. I cannot have this disk activity use up battery charge.
I need to know which application(s)is/are doing the disk activity so I
can shut it down for the flight. The Task Manager displays CPU usage but
this has not been very useful in finding which process is using the disk
a lot at the moment. Is there a way to monitor in real time which
process is responsible for disk activity in the same manner that the
Task Manager displays this for CPU usage?

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