Beryllium x-ray windows are used for shielding the detector while at the same time blocking unwanted radiation and hence providing minimal attenuation of the desired signal. Beryllium has very tiny atoms and very low density and thus absorbs relatively few X-rays as opposed to other materials. A characteristic that makes them suitable for maximum flux transmission and e specially where low energy transmission is desired.
Beryllium is useful for x-ray optics because x-ray absorption scales as Z2Z2 (Z is the number of electrons on the atom) so Be (Z=4Z=4) is in principle even better than diamond ( Z=6Z=6 ), cheaper, and easier to machine. They are used for windows to vacuum chambers and cryogenic chambers, to protect x-ray detectors from room light, laser light (and sometimes greasy scientist fingerprints). They can also be used on x-ray tubes and at synchrotrons to keep the electrons that create x-rays under vacuum, while letting the x rays into air.
Today, we're going to get technical: we're talking about imaging performance of X-ray tubes; and what kind of things you need to know as a purchaser of X-ray systems, to understand what vendors are communicating to you.
X-Ray Window Tubes:
One of the most fundamental things to know about the design of X-ray tubes is that they're basically light bulbs encased in a vacuum. However, on the outer part of the tube is a sort of "window" that is the aperture, or passageway, for the X-ray energy to exit the tube and enter your inspection zone.
These apertures are made from two types of materials: glass and beryllium ("Be"). Beryllium is the lightest metal in the atomic table. There are very different characteristics of X-ray tubes depending on what type of aperture sealant you have.
Low-Energy Photons
X-ray energy looks like a distribution bell curve. The distribution is essentially energy of photons. Let's say you have an X-ray tube rated at 70 KV. You would, of course, have some photons with more energy, and some with less. Low energy photons are ones that are less likely to pass through something without causing the detector to see them. That includes low density things like plastic, bone, and some stones. If you're trying to find these things, a beryllium X-ray tube is superior to a glass one because glass tubes filter out low-energy photons. That's what glass is: a filter.
If you imagine a chicken breast with a bone in it, with a glass tube you won't see anything; your image box would be blank. But with a beryllium tube, you'll see that bone with clarity.
Beryllium Window Tubes
If you want to get low-energy photons, you need a beryllium photon tube. So if you're buying an X-ray tube and you want certain types of contaminant detection, it's really important to appreciate the value of beryllium window tubes.
They're not offered by all manufacturers – but yitech trading offers all kinds of beryllium windows with all kinds of shape. We adopt HIP to process the beryllium products and our purity of beryllium can rach 99.9%.
Beryllium window tubes are more expensive to make. But their performance for certain applications is superior. So if your application can use a beryllium window tube, we highly recommend that you talk with us.