I would like an explanation about the physics that is happening inside the cold finger, which is a cryogenic that goes t

[answerhappygod]

I would like an explanation about the physics that is happening
inside the cold finger, which is a cryogenic that goes to low
temperature. I would like to know when two pumps (a mechanical one
that goes up to the pressure of 10^-3 mTorr, and the other a
diffusion one that goes up to 10^-6 mTorr) are connected to the
cold finger. They used thermodynamics to explain the physics behind
this and would like a full explanation. Thank you very much
This part is more theoretical and it is not an exercise
An example is the following image:

I Would Like An Explanation About The Physics That Is Happening Inside The Cold Finger Which Is A Cryogenic That Goes T 1 (880.34 KiB) Viewed 69 times

Compressors (input power and active phase shift) 300K Hot regenerator Gifford Mc Mahon Intercept Cold regenerator Cold tip Figure 1. Single 15 K PT, precooled at intercept.