Cross Section of a Transmission Electron Microscope Lens

Today I come across a sliced in half lens from a FEI 300kV FEG STEM. In other words a 300,000 volt Field Emission Generator Scanning Transmission Electron Microscope (More on that in a bit). I have not seen one of these sliced in half in a long time, and this one was a more recent version so I decided I should share!

NOTE: If you are new to this EM Bloggy thing, check out links to previous posts at bottom, especially Philip's EM 420 part 2. It should help ya fill in some knowledge gaps.

You can see some deformities in some of the orthocycling winding, and an especially a section when a wire steps up from the previous wind. Look for the blue line running at roughly a 45 degree angle from left to right, in the first picture below (In the Partiko app it is flipped and runs from the top to the right). I discussed orthocyclic windings in a previous post:

Orthocyclic Coil Windings in a Electron Microscope

Fig 1 - Look at how tight the packing is on those wires. They are about 1/16" thick

Fig 2 - Picture of the other side, look at how the gaps between some of the windings are bigger than other. Makes me wonder if thats why this guy was pulled or if they are all like that. The ungapped wire could also be from the cutting however, mushrooming of the soft copper. I intend to slice open some of our bad lenses, but that project keeps getting delayed. If you look at the bottom of this pic and #1 you can see two blue notches on the lense. Just below those notches are water channels for cooling. Allegedly, stainless steel, possibly copper tubing was running inside those channels. In older models copper tubing was cast or epoxied in*

Fig 3 - Top side photo showing power plug, and you can of make out the channels. They just loop in and out.

Fig 4 - Side view. Hmmm...interesting white stuff, sloppy epoxy? LOL

Okay so what is a Field Emission Gun? Well, without going into a lot of detail Electron Microscopes come with guns of 2 basic varieties. Thermionic, and FEG electron sources. FEGs have a electron beam with a smaller diameter, that is more coherent and much brighter than Thermionic. They are essentially superior. The disadvantage is their base and maintenance price is much much higher than thermionic, AND they are much more fragile. Also, users can change out a thermionic source as quickly as in 15 minutes, where as a FEG requires a high degree of training and can take days.

Scanning Transmission Electron Microscopes are hybrids between scanners and transmission type, and enable functions of both.

Reviving a vintage Transmission Electron Microscope - The Philips EM 420 part 1

Reviving a vintage Transmission Electron Microscope - The Philips EM 420 Part 2, a short description of TEM hardware and electronics.

Reviving a vintage Transmission Electron Microscope - The Philips EM 420 Part 3, Water Lines and Vacuum Gauges.

Reviving a Vintage Transmission Electron Microscope - The Philips EM 420 Part 4, Inside Some Penning Gauges, and More

Reviving a Vintage Transmission Electron Microscope - The Philips EM 420 Part 5 - Logic Circuits and Achieving High Vacuum.

Turning up the Electron Beam on a Electron Microscope

Inside the stage of a 0.22 nanometer resolution Transmission Electron Microscope

JEOL 4000 EX 400kV Transmission Electron Microscope Specimen Holder Loading Mechanism.