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DISCLAIMER!!!: This project can be EXTREMELY dangerous if you do not know what you are doing, in the case of this system, the x-rays are really the least of the problem, assuming you have something to protect yourself with. However a flyback transformer can give you a nasty shock that could even kill you in some cases. The X-ray emission from this project is not dangerous if you understand the physics and protect yourself from it. Regardless, shielding is a necessity. I am NOT responsible for any damages to people or property if you attempt this.



PREFACE:
This is an Instructable covering the first part of a project I have wanted to do for some time now. After watching various videos and studying up on how x-rays were produced and interacted with the world around them, I decided I would very much like to experiment with them, as I have a well vested interest in high energy physics and electronics. I did not wish to spend many hundreds of dollars or possibly thousands on a real x-ray setup, as I wanted to experiment now and wished to see if I could produce them cheaply, reliably, and repeatably with parts I already had or could very easily acquire.
As for background, X-rays are very high energy photons produced when an accelerated electron strikes something and returns to its ground state. So to produce them, you must accelerate electrons to an appropriate energy to release an x-ray. This energy is measured in electron volts, or eV. There are also two categories of x-rays that we will associate with; Soft x-rays, and hard x-rays. "Soft" or "Low energy" x-rays are produced at around 800 eV to 5 KeV, while so called "Hard" or "high energy" x-rays are produced at energies greater that 5 KeV, upwards to 100 KeV. Soft x-rays are produced by this project, and are unable to penetrate objects as well as hard x-rays, and are often absorbed in air or your object of study. Therefore they are not typically used for imaging, due to scattering and absorption. Hard x-rays can be absorbed or pass through different materials, and their different rates of attenuation can show images when projected at a screen sensitive to x-rays. Essentially like shining a light on something and creating a shadow, materials that attenuate hard x-rays more readily will show up white, as x-rays have not penetrated through that material and made it to your imager, Whilst when hard x-rays do penetrate through, they hit your imager and leave no shadow. The x-rays produced by this system will typically be absorbed in air or water due to their relatively low energy, and are not useful for imaging, however you can still measure these x-rays, and I will speak more of this in the other part of this project, the detector.

*soft x-rays can be considered much more dangerous due to their higher rates of absorption, so care must be taken, and shielding worn or placed between you and the emitter.*

So came the first component; the tube. I am an avid collector of different valves and interesting vacuum or gas filled electron tubes. It so happened that I had a High voltage beam triode, which when operated in a cold cathode configuration, meaning the cathode was not boiling off electrons due to thermionic emission, I could accelerate electrons to an appropriate High energy for x-ray production.


Step 1: The Source

My source is a High voltage beam triode from RCA, The 6BK4C 6EL4A. This tube is very well suited for this since it has; 1. A physically far apart Anode and Cathode, this will prevent arc out and degradation. 2. A well documented datasheet that states its level that it produces X-rays at. 3. It is robust, and simple.

There is one drawback to this particular tube, and that is that it is a revised version of a previous tube. It is a revision equipped with leaded glass to reduce x-ray emission. Nevertheless the stated production rate is somewhere in the neighbourhood of 2 rads per hour. The leaded glass will not prove to be a terrible hindrance, as the tube is quite active.

Step 2: The Power Supply

The tube isn't going to produce x-rays when it wants to, the electrons must be accelerated. To do this without tearing my wallet in half I chose the trusty Mazilli ZVS flyback driver. The ZVS, or zero voltage switching driver is a tried and trusted way to produce high voltages reliably and cheaply, you can read more about the circuit I used here https://www.instructables.com/id/ZVS-Driver/ as it has many many uses other than this.
After mucking about with the turn ratio on the primary and feedback winding and changing values of inductors, etc. I had reached an appropriate output voltage of 27,000 volts, My triode is stated to produce x-rays as low as 16,000 volts, so this is perfect. Other than changing values and flybacks, my ZVS circuit is Identical to the schematic of the Mazilli ZVS, I am not sure of the exact value of my inductors, as they were stock I had in my parts bin. Mess around! if you are building a ZVS driver, Just mess with it! They will always give you something to go by, even if it is disappointing.

Step 3: Detection and Safety

When you build something like this, It is important to protect yourself appropriately and Detect them to test if you were successful. This is harder than It might sound, as I ran into an interesting failure mode.

I am using a Russian SBM-20 based Geiger counter kit that the awesome Jeff Keyzer "MightyOhm" sells, This tube is sensitive to 1 KeV Emissions and also provides me with a serial interface for measurement and datalogging.

For protection I wear a lead radiology jacket that was donated to me by a very generous individual. If you can not afford one of these jackets or no one has donated one, A sheet of lead may be used, but with lead, you must be careful with your placement of shielding. Being soft x-rays, most will absorb in air over distance, however those that make it to you will be absorbed in your skin, so shielding is quite important.

The failure my first trials experienced were that of false reading. My Geiger counter is open framed, so it is susceptible to Ion wind discharges or corona from exposed wires at close distances. so for appropriate measurement the Geiger counter must be a at least 4 inches away, for the sake of assurance I put mine 5 feet away. The first iteration of this device did not successfully produce x-rays, as the power supply only output 10,000 volts. To low to produce enough x-rays in this tube. This led to a redo and retesting, this time with distance and higher voltage, resulting in x-rays being successfully produced. I will be gathering long exposure pictures of the tube glass fluorescing and hopefully the fluorescence of my x-ray intensifier. I will follow up with more information as this project is completed.

Step 4: Measurement Results

Here are the results of testing my X-ray generator intensity with an SBM20 Geiger Muller Detector at three feet away in 2 and 5 second bursts:

CPM: counts per minute
uSv/hr: microsieverts per hour
CPS: counts per second

Background Radiation:
CPM: 23 uSv/hr: 0.14

Two second generator burst at three feet away:
CPM: 2300 uSv/hr: 12.72 (counter switches to fast measurement mode)

Five second generator burst at three feet away:
CPS: 84 CPM: 3996 uSv/hr: 22.77 (counter is switched in fast mode)

Step 5: WIP

This project is a Work in progress, and is in the process of having data gathered. I will be shooting video and long exposure pictures of the device operating, to see if I can catch my x-ray intensifier cassette glowing and also catching the tube glass fluorescence. I have gathered some data of x-ray energies in counts per minute, and dosage rates in millisieverts. The final part of this project is a detector made from a retired high performance liquid chromatography machine detector, called a fluorescence detector. I have put a peice of intensifier film inside the Photomultiplier chamber and hope to see activity with this, This is a halted project for the time being however as I am in the process of moving, and in other projects.

For more updates more frequently refer to my blog, http://Spectrhz.wordpress.com

<p>If I might make a recommendation--there are still 01 201A tubes out there. They are the old timey tubes with a brass base. The inside top is a magnesium 'getter'--the magnesium was a part of the vacuuming process at the time. Anyway you might get a more directed beam with one of those. (fashion a moulded aluminum cap on tip, wire to ground). :]</p>
<p>what is the exact name of the tube you mentioned? There seems to be a variety of 201A's out there...</p>
<p>Which pins of the BK4C 6EL4A do you use?</p>
<p>I use pin 1 on the base, which is the cathode pin. In reality though, since this is a cold cathode x-ray generator you can use any pin that connects to internal metal structure, it's mostly about just having a large voltage potential across the tube with a gap in between. Any vacuum tube that has a large gap will emit x-rays at high enough voltages. The pins would only matter if you were using a hot cathode tube, where you have a low voltage high current that heats a filament, and a secondary high voltage to accelerate the electrons that come off the filament.</p>
<p>Mine worked only when I used pin 8.. Pin 1,2,3 did not produce any &quot;glow&quot;, only pin 8 did..<br>Say, what is the number of the tube that does not have the lead in its glass?</p>
<p>Many thanks.. so, one lead goes to pin one, and the other one?</p>
<p>Yes, one pin goes to the cathode on the tube, but we are using it backwards, using the cathode as the anode. The anode of the tube is the big nib on the top of the tube, but we are using it as the cathode.</p>
<p>L&agrave;m thế n&agrave;o để l&agrave;m cho ống x-ray?</p>
<p>Making the tube itself would only be possible if you had an ultra high vacuum system, glass blowing skills, and the components necessary to make a vacuum tube. (electrodes, getter material, leak detectors) It's significantly easier to source a retired triode or x-ray tube.<br><br>apologies if I misunderstood your question, I only have google translate.</p><p>L&agrave;m ống ch&iacute;nh sẽ chỉ c&oacute; thể nếu bạn đ&atilde; c&oacute; một hệ thống ch&acirc;n kh&ocirc;ng si&ecirc;u cao, kỹ năng thổi thủy tinh, v&agrave; c&aacute;c th&agrave;nh phần cần thiết để tạo ra một ống ch&acirc;n kh&ocirc;ng. (điện, vật liệu getter, ph&aacute;t hiện r&ograve; rỉ) N&oacute; dễ d&agrave;ng hơn đ&aacute;ng kể v&agrave;o nguồn một triode đ&atilde; nghỉ hưu hoặc x-ray tube.<br><br> xin lỗi nếu t&ocirc;i hiểu lầm c&acirc;u hỏi của bạn, t&ocirc;i chỉ c&oacute; google dịch.</p>
<p>Thank you!</p>
<p>This is a really interesting instructable. As a radiologic technologist, though, I have a problem with your explanation of the physics behind &quot;hard&quot; and &quot;soft&quot; xray. X-rays do not reflect. They can, at times, and at low energies, &quot;scatter&quot; due to the way they interact with the electrons (or protons/neutrons) in the atoms they hit. Low energy x-ray is more susceptible to scatter because it is more likely to attenuate in the subject being radiographed. <br><br>A radiograph is essentially a shadow. Things that are white are that way because the x-ray has attenuated in that particularly dense subject material: bone, barium, dental fillings, and to a lesser extent, soft tissue, etc. Things that are black are so because the x-ray has passed through and made it to the imaging plate (whether digital or film) Xray passes easily through air and fat, this is why your lungs appear black (with some markings) air bubbles in your stomach will appear when you're standing for your chest xray, etc. </p><p>So it is essentially not a matter of your low-output x-ray being 'absorbed' by the subject, but rather that your source is powerful enough to project the photons through your subject matter and onto the film, thereby leaving the indelible mark of its shadow in your silver halide. </p><p>The risk of using this sort of device for medical imaging (which would not be legal or safe!) is that your x-ray photons would indeed be absorbed, and in their attenuation, be far more dangerous to your bodily cells than regular, high-power medical imaging. Absorbed x-ray photons essentially equate to 'dose'.</p><p>It's best to think of it in terms of a shotgun blast into ballistics gel- a very low-powder load (as this would be) would have much of the shot stuck in the gel, where it can do damage. A high-powder load (as with medical imaging) would pass through, and given the specific application is precisely calibrated to achieve the best image possible while still giving the patient the smallest possible 'dose' of radiation. I hope this has helped. For further information, auntminnie.com is a great resource, as well as any books by Stuart Bushong and Carlton-Adler. </p>
<p>Hi! thank you very much for the comment, it is very in depth and excellent information! </p><p>I will be the first to admit I do not know everything and have a lot to learn, as for the hard and soft explanation I took that from someone else, and it is certainly not a good one, however you have given me more insight. I am certainly not going to use this for medical imaging, as since it is not a point source, and would be rather difficult to use, if not impossible (nor am I interested). I'm not totally sure if these x-rays are of a high enough energy to light my cassette... I will keep improving this, it isn't finished, after all. </p><p>-SpectrHz</p>
<p>Very interesting!</p>
<p>Thank you :)</p>

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