I’ve spent the last several blogs looking at several different performance metrics for LDOs. In this installment, we will take a look at an important aspect of product development for the space market, radiation testing. The title I have chosen has a few interesting meanings for this blog. Considering the time of year and all the Christmas lights abounding, it made me think of my recent experience performing radiation testing at the Cyclotron Institute at Texas A&M University down in College Station, Texas. I was there looking at radiation effects on one of our products at Analog Devices. I recall growing up thinking of radiation making things glow or, as we may have called it, being lit up like a Christmas tree. The expression has other meanings but I think it serves the purpose here pretty well in a discussion of radiation testing.
One of the many important aspects of the environment in space to consider is radiation. Products must be at least radiation tolerant to perform in the harsh environment of space. Without the Earth’s atmosphere to offer protection, products in space are exposed to many different forms and amounts of radiation as well as other things like solar flares, cosmic rays, etc. For a little more insight you can check out two blogs from my colleague Kristen Villimez at Jupiter: The IC Danger Zone, Part 1 and Jupiter: The IC Danger Zone, Part 2. As can be assessed from these two blogs there are different levels and types of radiation exposure depending upon your location in the galaxy. Jupiter turns out to be a pretty harsh location for radiation.
So let’s move on and take a closer look at the cyclotron at Texas A&M. There are several of these facilities in the United States and around the world that can be used to perform radiation testing. As a matter of fact, many hospitals have a facility to perform radiation therapy for cancer patients. Obviously these facilities aren’t conducive to testing electronic devices since the facilities at a hospital must be kept sterile. Upon arriving at the Cyclotron Institute at Texas A&M, my first impression walking into the control room pictured below was: “Wow! The control panels are lit up like a Christmas tree!!” This is another way I would think of this expression growing up when I’d see something that had many lights on it. My next thought was how much it reminded me of a movie from my childhood, War Games. The control room reminded me of several scenes from that movie from their control room such as the one pictured here: War Games: Control Room. Can you see the similarities?
Cyclotron Control Room at the Cyclotron Institute at Texas A&M
In so many way it is impressive that this facility has been in operation for as long as it has. From what I can gather via online search it appears that it has been in existence since approximately 1967. I am not sure which to think is more impressive; the fact that it is still operating well or that engineers so many years ago were able to design and build this system to do the things it does with the available technology of the day. I suppose that it should not be that much of a shock since we were able to place men into space in the same decade. Take a look at the photo of control panel area one with the analog gauges and all the push buttons on the display. These are not something you see very much of today!
Control Panel Area One at the Cyclotron Institute at Texas A&M
Control Panel Area 2
Looking at control panel area two you can see more push buttons and a huge area of potentiometer-like controls. Again, this is surely something you do not see a lot of today. The displays remind me of the old alarm clocks that I used to have with the seven segments for the numbers. It definitely takes me back a few years! I’m left wondering, “What do all those buttons and potentiometers control?”
Control Panel Area Two at the Cyclotron Institute at Texas A&M
Last, but certainly not the least of the cool things at the cyclotron, is where the actual radiation beam exits the cyclotron and is used to irradiate the devices being tested. You can see this is quite a piece of machinery from the photo below. Notice the metal cap with the “X” marked on it. This is the actual point where the radiation is emitted. The device under test would be placed directly in line with this point so that it can be irradiated. A key reminder is due here: This is NOT where you want to be during the test! There is an isolated chamber above the radiation beam area that is safe from any exposure to the radiation emitted by the cyclotron.
Radiation Beam at the Cyclotron Institute at Texas A&M
The device under test is set up in front of the radiation beam and all the necessary cabling is routed up to the isolated chamber above the radiation beam where the user controls the device and associated test equipment. The chamber has a telephone line back to the main cyclotron control room so that the control room can enable and disable the radiation beam at the appropriate time (of course, the beam is always disabled while any person is present with the radiation beam). Depending upon the level of radiation testing required different elements can be used to achieve different levels of radiation. In the particular set of tests performed during the experiments I was a part of, radiation levels from 20 MeV up to 80 MeV were used.
Overall, this was quite an interesting experience for me. I was quite impressed with the technology in the control room. One would fully expect to see that latest and greatest in technology, but instead you are greeted with old school analog meters, dials, and push button controls. It is such a great testament to the ingenuity of the engineers who designed this equipment to perform the operation it does and to last for such an extended period. I left quite impressed with the cyclotron. I look forward to getting a chance to return and perform tests on other devices. I’d like to thank the great folks at the Cyclotron Institute at Texas A&M for maintaining this facility and leasing out its use for folks like myself to perform radiation testing on devices.