1. How to design a vacuum system, including the following.
Mean Free Path of gas molecules: Viscose flow Vs. Molecular flow
Gas flow: Throughput, Conductance, Pumping speed
Pumps: Mechanical pump, Roots, Turbo, Diffusion, Dry pumps
Gauges: Mechanical, Thermal conductance, Ionization,
Chambers: Joints (metal, elastomer), parts
Surface outgas
Material: SUS, Al alloy, ceramic, plastic,
Virtual leak
Baking
Leak test, etc.

2. How to design a machined part.
Mechanical drawing, tolerance and fit, thermal expansion, …
Material: SUS, Al alloy, ceramic, plastic, …
Machining methods

3. How to design an optical system
For example, a spectrometer.

4. How to deal with electronic signals
For example, signal reflection and filtering.

5. How to design ion optics (if time allows)