X-ray and Electron Optical (XEO)
Welcome to the XEO Division of Torr Scientific which focuses on X-ray and Electron-Optical products. The newly built clean production facility is dedicated to production of X-Ray Anodes and Sources, Electron Sources, Phosphor Screens, Microchannel Plate Assemblies. For further details, please use the Product Divisions menu or contact us on email@example.com
Torr Scientific is a company that manufactures components and assemblies for UHV (ultra‑high vacuum) technologies. Its manufacturing competencies include joining of dissimilar materials, thin-film coatings and hermetic seals, all of which are applied to the manufacture and refurbishment of X-ray anodes. The technical capabilities include optical coating design, 3D-CAD (computer-aided design) electron/ion optics modelling and FEA (finite element analysis).
These devices use electrostatic and magnetic fields to move a set of charged particles (normally electrons) in a controlled manner. The internal workings are often referred to as electron optics as they act in a similar way to optical lenses on a light beam. They are important for the design of machines such as electron microscopes and particle accelerators but cover a wide range of applications.
A phosphor is a substance that exhibits luminescence, where it emits light when exposed to different types of radiant energy. When the phosphor is coated onto a substrate it can be called a phosphor screen, in Torr’s case we normally coat phosphors onto glass optics.
There are many different grades of phosphor, often denoted by a P followed by a number (P11, P42 etc.) which have different properties including the wavelength of light emitted and the delay time (the time it takes to stop emitting light after activation). Recent examples would be CRT (cathode ray tube) televisions where a very fast-decaying phosphor would be used as the screen needs to be rewritten many times a second.
At the other end, old-style radar screens had a slow-decay phosphor which kept the image visible for several seconds.
The use of the word phosphor is misnomer here, they are based around materials such as copper-activated zinc sulphide. Phosphorus emits light by chemiluminescence, phosphors by phosphorescence.
Microchannel Plate Assembly
A microchannel plate (MCP) is closely related to an electron multiplier. They act as particle multipliers and are used to detect single particles such as electrons, ions and neutrons, as well as photons.
Normally manufactured from glass, they are predominantly disc shaped and contain a regular array of numerous microscopic tubes (each around 10µm diameter) which connect from one face of the plate to the other.
The channels are parallel to each other and are slightly angled around 10° relative to normal.
A high voltage is placed between the top and bottom surface of the plate. Any incoming single particle entering one of the tubes will hit the wall (due to the angle and accelerating voltage) The collision liberates several electrons, each of which is accelerated along the tube, striking the wall and producing more and more electrons. In this way, a single particle can produce a detectable cascade of 10,000 or so electrons. A detector is placed underneath the bottom plate where it collects the electrons.
The detector can either be an anode for pulse counting, or a phosphor screen to generate an image. MCP’s can be stacked on top of each other, normally in stacks of 2 or 3 to increase the number of electrons produced and increase the sensitivity.
X-ray anode source
X-rays were discovery by the German scientist Wilhelm Röntgen, who called them X-rays because their nature was unknown.
When an energetic charged particle is deflected by another charged particle (typically an electron by an atomic nucleus), the resultant deceleration causes the incoming particle to lose energy as electromagnetic radiation, producing a continuous broad spectrum known as bremsstrahlung (German for braking radiation). Superimposed on this may be sharp peaks that are characteristic of the elements present.
In an X-ray anode, electrons are produced in an electron gun and then accelerated into a metal target. This target can be manufactured from different materials, copper, molybdenum and tungsten being popular.
The conversion process to x-rays is about 1% efficient, the remaining energy is lost as heat, so the anode may be cooled by a flowing source of water or oil underneath the focal spot.
The X-rays have a characteristic energy spectrum which depends on the anode material. The x-rays produced can be used in a number of ways including medical imaging, radiotherapy, & non-destructive testing.