How can we contain something that gets as hot as 100M Celsius? And how can we measure it?

Question

I have been reading articles describing the progress made towards fusion energy and got intrigued by how they do it.
https://www.msn.com/en-us/money/other/nuclear-fusion-reactor-sustains-plasma-at-100-million-c-for-30-seconds/ar-AA11BpC8

In: 71

Answer 1

The plasma created by the fusion is magneticslly charged and can be contained and routed via superconducting magnets in a device called a tokamak. That contains much of the energy. Additionally the internals are reinforced steels designed to take reduced damage from fusion heat and neutron bombardment.

I do not know how long one could continuously. I think the longest contained fusion reaction was under 15 minutes so far.