Re: X-Ray VS Magnetron?
lpfthings, Sat Apr 12 2008, 01:25PM

Deffinately nonsense, magnetrons emit radiation in the 2.4ghz feild, not even close to x-ray frequency.

Re: X-Ray VS Magnetron?
Proud Mary, Sat Apr 12 2008, 02:10PM

Not definitely nonsense at all. It may possibly work if you remove the magnet, don't apply heater current, and apply a sufficiently high voltage.

Many types of thermionic valves [USA: "tubes"] can be driven to produce X-rays by cold cathode discharge by running them at a suitably high voltage without applying heater/filament current.

Popular valves used by amateur X-radiographers are PD500 [in Europe] and the 6BK4B [in the United States,] which are similar EHT shunt stabiliser triodes used in valve-era colour television sets.

Many television EHT rectifier diode valves can also be made to give enough X-radiation for amateur experiments.

A magnetron - which has already been designed to hold off quite large voltages - could very likely emit X-rays if you discard the magnet, do not apply heater current, and stick 40kV and more across it in a suitably safe way.

Make sure you have a reliable means of detecting and measuring any X-rays produced, and be very careful indeed with all that you do.

Re: X-Ray VS Magnetron?
Dr. Mario, Thu Sept 30 2010, 11:45PM

You will have to apply the heater current, since Magnetron was pumped to the same Torrs as X-ray tube, it's so that way the microwave don't get attunated when being resonated among capacitor ring inside it. So you will have to apply the power to heater, then Presto, a powerful X-ray tube! When I say "Powerful", you would get away with 200mA of 50kV - but be especially warned when you hack that magnetron tube: That stuff will emit especially nasty hard X-ray (0.8 - 0.01nm - depending on how much you're willing to punish your inverter...). Mucho power can be obtained with Marx - up to 5 Megawatts pulses. You would definitely don't want to stand in the front of your newly-bapisited X-ray tube, a very bad idea...

Re: X-Ray VS Magnetron?
Adam Munich, Fri Oct 01 2010, 12:38AM

The only possible use I see for this is a death ray. If you apply 75kV at 200mA you'll get a ridiculous amount of radiation, but it will be unfocused and moving in all directions. Thus it'll be unsuitable for taking any pictures.

Re: X-Ray VS Magnetron?
Proud Mary, Fri Oct 01 2010, 07:59AM


If you connect a 50kV 200mA supply to a heated oven magnetron, the magnetron will be destroyed immediately.

However, if the magnetron is left unheated, then some X-rays will be produced by field emission electrons impacting the anode if a sufficiently high voltage is applied. As soon as heater current is applied, the voltage drop across the valve will fall to a low value insufficient for significant X-ray production to occur.

The more thoughtful and discerning reader will remember that some old TV EHT valves only became X-ray hazards when their heaters had failed, so the voltage drop between anode and cathode rose to the full EHT supply voltage and field emission occurred.

Re: X-Ray VS Magnetron?
cedric, Fri Oct 01 2010, 10:32AM




I did it ,once .
removing the magnet from the tube,for the power supply I use a microwave oven transformer ,his capacitor and a spark gap dumping the capacitor in to a double plastic boxed car ignition coil . it give about 140 kv output in 100 hz,with a lot of current. the spark gap was set at one millimeter,
next ,I plug the anode in the transformer along with one of the side of the ignition coil and and the cathode on the other side of the coil.a lot of tape to give some sort of dielectric isolation
first time I tested ,my geiger counter want crazy ,even at 3 meter from the set up,first I was thinking it was du to the electric field who might have influence the counter, but than I tested with a fosfor screen and I sow the light ,it escape from the ceramic side ,the copper cathode is way to thick to let much out ,I think that this day I get my ten year radiation dose all at one,not very smart ,any way in this set up the system could not work more than few second at a time or the tube would get destroy ,and after some time the ignition coil left this world in a flaming and smoking agonies.
a magnetron with out magnet is just a high power vacuum diode,so there is no problem getting radiation out ,now for practical purpose ,an x-ray tube is much more efficient and a lot less dangerous (at list you know where most of the radiation are going..)

Re: X-Ray VS Magnetron?
Proud Mary, Fri Oct 01 2010, 12:02PM


X-rays of wavelength 0.01nm have an energy of 124.125keV, so this wavelength could never be produced by a 50kV supply, no matter what sort of X-ray generator was used.

The shortest X-ray wavelength possible with a 50kV supply is 0.024825nm.

Moreover, X-rays of wavelength 0.8nm have an energy of 1.55keV, and rather than being "especially nasty hard X-rays" are so extremely soft that they would be unable to leave the magnetron shell, and even if we were to imagine that they could, then specialised instruments would be needed to detect them,.

Are you reporting nonsense you have seen elsewhere, or just making it up as you go along?

Re: X-Ray VS Magnetron?
Steve Conner, Fri Oct 01 2010, 01:02PM

Did you do this with the filament on or off?

Re: X-Ray VS Magnetron?
cedric, Fri Oct 01 2010, 01:45PM


on ,the filament was plug on the small secondary of the MOT.

Re: X-Ray VS Magnetron?
Dr. Mario, Fri Oct 01 2010, 10:23PM

Well, Proud Mary, it's what you think, but I stand by my experience. I would like for you to use the X-ray spectrometer to prove it. I am not being jerk, but from where I am standing, X-ray gets harder once voltage climbs over. You really have to get and read Dentist or CT X-ray equipment owner's manual to really find out. Presently, I have NO way to know unless I get some nifty X-ray spectrography hardwares (which I would really need as I am building a X-ray laser using alpha pinch in Helium with 60kV or higher rushing through callipary - I am imagining I would only be getting Neon-IV lines, which is in soft X-ray lines, or Nitrogen-III in EUV bands - if I am really lucky, I may get middle-wave X-ray, Oxygen III Ion line of 933 Picometers, but never harder... I am gonna need spectrometer on this one...) - in other word, I will really forget about using Magnetron for X-ray, they STILL are capable of Hard X-ray (which you will only get away if you provide LOT of cooling....)

Which, in many case, I would perfer to use X-ray laser, as it's a bit safer in much respects, you would know where the light go, and it doesn't spread out as much as a X-ray Coolidge tube....

Re: X-Ray VS Magnetron?
Proud Mary, Fri Oct 01 2010, 10:35PM


You seem not to understand the fundamental relationship between X-ray photon energy, X-ray wavelength, and X-ray source anode voltage.

You should try to learn how to stop embarrassing yourself and others with confused confabulations of this kind, if only because it is preventing you from actually learning anything about a subject in which you are clearly interested. And with that I shall wish you goodbye, and good luck.

Re: X-Ray VS Magnetron?
Dr. Mario, Sun Oct 03 2010, 08:24PM

Me confusing the others? I knew better than that. I wouldn't dare to microwave myself, and it's the thermal gradient that would cook my eyes, and X-ray is 100 - 1,000 times worse than that. It rips electrons out of molecules, it's what it do, since it got massive energy in the photon packets (X-ray wavelength is ultra-short compared to Microwave wavelength).

If you want to kick me out, go ahead. Think about it before you do. Get a science book on optics and lasers and you will see why I would not dare to say, "Hey, it's cool to X-ray yourself, and you will glow in the dark", it's real wrong. I knew better than that.

Re: X-Ray VS Magnetron?
Arcstarter, Mon Oct 04 2010, 12:19AM

I have even seen people make X-rays by putting some alu foil on the top of a tube without an anode cap. They connected all of the pins together and hooked them to a Tesla coil, and i guess the aluminum foil was grounded. Apparently they got X-rays, otherwise they would not have put it on the internet :)

Re: X-Ray VS Magnetron?
803, Mon Oct 04 2010, 12:42AM

Perhaps.........


it's real

Perhaps....

IT's popycock.

What do you think?

Re: X-Ray VS Magnetron?
Proud Mary, Mon Oct 04 2010, 08:50AM


An article called "An Inexpensive X-Ray Machine" in the now famous Scientific American Book of Projects For the Amateur Scientist, Simon & Schuster, 1960,
describes just this, and was my first inspiration to have a go myself.

The author, Harry Simons, used field emission electrons to bomabrd the magnesium getter inside a long obsolete thermionic valve he specifies as 01. This 1930s valve seems to have been the RCA-01-A described as "a three electrode storage battery tube for use as a detector and as a amplifier."





When these 1930s valves became unavailable, Simons had cold cathode tubes like the one below made to order for $15 - none too cheap in 1960, when the average wage of an African-American female was $9 per week. The technique of using a thin film anode such that X-rays emerge from its back is still used today in 'transmission target' analytical X-ray tubes.






Simons used an AC circuit such that the 'anode' - the magnesium getter - is powered via the capacitance between the getter on the inside, and a foil wrapping on the outside, of the glass. As a grounded anode tube using AC, the device would only have emitted X-rays on the negative half cycle, a situation which must have caused both amplitude and frequency modulation of the pulsed beam.







The high voltage AC was produced by an Oudin coil of Simons' own design:





Lacking a distinct anode focal spot, Simons' radiographs lacked resolution.

Re: X-Ray VS Magnetron?
Dr. Mario, Tue Oct 05 2010, 11:08PM

Well, X-ray from funny-looking arrangement (a light bulb with Aluminum foil) won't give you hard X-ray, no matter how hard you crank up, or how hard you look at it. It's because there is Argon atmosphere inside bulb that will slow electrons down, very narrow mean-free-path for them (think of heavy metal ball you usually throw at track meeting, being dropped into swimming pool. Why wouldn''t it dent a floor? It's water that impose lot of friction resistance - same with electrons in Argon gas). Plus, Glass have very narrow energy density (lot of Boron and Silicon which can either kill off hard X-ray or absorb it until it overheats and shatters - it also slow electrons down - considerably more than in Argon gas.) - I did just that with small bulb, no useful X-ray, they were absorbed even by thin glass envlope, evidenced by aqua-green lights (if you crank it up, it will just arc over the bulb happily no matter how well you try...). I was bored and tried this method.

For that reason, they switched to hard vacuum tube for even more useful X-ray lights for medical and welding work (BTW, industrial battery-powered X-ray machine at welding work area loves to eat its own batteries even after few minutes - it got monstrous inverter inside it - everything overkill in term of size and current rating. In the end, they want brightest X-ray as possible so they CAN find faults in thick metals being inspected for crappy welding jobs. Sometimes, for solid metal post, they just resort to gamma-ray radiography, if X-raying that weld job was futile.)


BTW, it's still always possible to extract useful X-ray in just right condition. Experiment until you can find the best exposure with that light bulb tricks. (ALWAYS HAVE A GEIGER COUNTER OR ANY OTHER X-RAY SENSORS ON YOU, IT'S BETTER TO BE SAFE!)

However, I have been wondering, do the gas pressure have any effect on X-ray generation, as per the individual bulbs??? I would love to know why... BTW, clear (fridge) bulbs work better than frosted ones, due to Telflon powder which is an insulator.

[Edit: Double post]

Re: X-Ray VS Magnetron?
Bjørn, Wed Oct 06 2010, 02:20AM

Different light bulbs contain different things, ranging from vacuum to high pressure gas mixes. So you can't make any general statements regarding how well they can generate x-rays. The picture does not show a light bulb at all so it is hard to see where that comes in to play.

Just leave it with the fact that for every thing you think you know about something, Proud Mary knows 100 times more and has the references to back it up.

Re: X-Ray VS Magnetron?
803, Wed Oct 06 2010, 09:14PM



Mary, the '01a is still here, you can buy it for $20. It's used in antique radios from the 20s and 30s. it's real name is the 201a




Bjorn, don't you think that's a little too harsh? at least he's trying!

Re: X-Ray VS Magnetron?
Dr. Mario, Wed Oct 06 2010, 09:42PM

Yea. However, I am no longer going to post, left off only to view the website maybe download something.
And, there are something that Proud Mary may know what I don't, though.

BTW, I got magnetron tube - need to crack one more magnet (just worried about BeO inside the heater cover... Reddish pink ceramic at antenna end may be of Aluminum-based ceramic or maybe something different, so I am going to think of best way to crack the last magnet without cracking that nasty stuff - biohazard stuff is one thing I would think twice...)

And, I may have to start calculating the lowest point then drive it up slowly - trying one thing at the time.
(I may try drive it as low as 24kV to 33kV at 500uA or so, depending on how hot the heater is - since magnetron is pumped down real good at the factory - if you have accidentally dropped the magnetron, you may know what I mean... =P )

I am not going for powerful X-ray for now (as a precaution), I may intend to use X-ray from a modified magnetron tube for sensor testing (scintillator or direct-detection) for now. I am planning to construct X-ray laser later on - based kinda on US Patent: 5467362 - Pulsed gas-discharge X-ray laser. (This one is gonna push the limit of how I know everything works: the capacitor high-voltage rail is something like TEA Nitrogen laser's. Very hard since ESR must be very low - I may try SMD capacitors soldered on Copper rail and build them up in bothy Parallel and Serial wiring - and I may need to find the best Thyratron - it's going to cost me pretty pennies....)

Re: X-Ray VS Magnetron?
Proud Mary, Wed Oct 06 2010, 10:08PM


Oh, what makes you think that? I understood that 201-A was superceded by 01-A, but don't understand how RCA calling this valve "01-A" in their data sheet can not be 'real?'

01-A is first referenced in the Cunningham Radiotron RCA Manual 1934, Technical Series RC-12, p. 62.

Re: X-Ray VS Magnetron?
Arcstarter, Thu Oct 07 2010, 11:12PM

I was actually just looking at the article you've posted, Proud Mary. It was much like that, though it was an actual Tesla coil, and alu foil on the outside rather than the foil and getter's capacitive coupling.

Though, i can definitely see why an internal target capacitive coupled to the supply would be best. I guess that is why the high freq from the Tesla coil was used.

edit: I tried to make some X rays with this magnetron and it did not seem to work. I covered the whole magnetron with a fort of MOTs for shielding and used a remote switch. I tried it with and without the heater, in both cases there was at least 60kv across the tube. I had it in an oil bath because the heater wires would arc over at around 20kv. The current was high, and pulsed, but obviously there was no need for it because even with the heater visibly on, it still had 60kv drop O_O.

It is a working magnetron, magnets and fins removed. I used a couple HEI ignition coils in anti-series, and an SCR driver that charges a 20uf cap from the mains, and fired with a triac/diac combination. I used my camcorder to pick up any X-rays, as the X-rays would strike the CCD and light up a few pixels, like in this video of mine:

Also, a somewhat related question. Would X-rays make phosphor fluoresce?

Re: X-Ray VS Magnetron?
Proud Mary, Thu Oct 07 2010, 11:37PM


I believe that in the first year or two folllowing Roentgen's discovery of X-rays in 1895, that the rays were produced by the impact of electrons on the glass wall of Crookes' (tear-drop shaped) Tubes.

Re: X-Ray VS Magnetron?
plazmatron, Fri Oct 08 2010, 12:11AM

I once had access to 1800`s to 1900`s copies of Scientific American at the Library, and did quite a bit of research regarding x-rays in this period.

Very shortly after the initial discovery of x-rays, there were several articles printed, on the production of x-rays using available components, including carbon filament bulbs, of which the filament was connected to one pole of an induction coil, and the other pole of the induction coil was connected to a foil cap placed on the light bulb.

The first bulbs in case anyone was wondering, are a reasonably hard vacuum, and were not gas filled.

Sound familiar?

There was also printed in those early copies a veritable cookbook of homemade x-ray sensitive phosophors.
I miss the old Sci-Am it was full of such wonderful practical science!

You do not necessarily have to use a Tesla/Oudin coil to capacitively couple through a glass envelope, however, as I recall a "coil producing a spark of not less than six inches" had to be used for these early experiments using induction coils, and lamps.

High Dv/Dt, is the most crucial factor in efficiently driving tubes in field emission mode, which is why flash driving works superbly, followed by Tesla/Oudin/Induction coil driving, with CW giving the poorest results.


Les

Re: X-Ray VS Magnetron?
803, Fri Oct 08 2010, 12:24AM



well, you got me, I thought you ment the 201a as mostly, the 201a is mostly called the '01a. It still used the mag. getter, so I could still be right!.

so much pomp....
I think there interchangeable.

my 0.02

Re: X-Ray VS Magnetron?
Arcstarter, Fri Oct 08 2010, 09:10PM

I found a website that has something similar to the page i was describing, and similar to the page Proud Mary provided.



Notice, it is not grounded, the capacitance from plate to ground, i figure, is high enough. Or, maybe the capacitance from cathode to anode loosely couples them, and the capacitance from the internal parts to ground allows X-rays to be created.

Re: X-Ray VS Magnetron?
Proud Mary, Fri Oct 08 2010, 10:22PM


X-ray tubes (and valves tortured into producing X-rays! ) can be operated in three basic modes:*

1) Grounded anode - where the cathode/filament is at a high negative voltage, so the tube conducts only on the negative half cycle of an AC current as in the old Scientific American article. This method is often used in fixed (non-rotating) anode tubes with water cooling , because it enables the anode block and the cooling water supply to be held at ground potential while bolted to a metal structure or housing. This method has the disadvantage of needing a floating filament supply, in tubes using a thermionic cathode. (I use Hawker Cyclon lead-acid cells for this purpose)

2. Grounded cathode, where the anode is held at a high positive voltage. This method does not require an isolated floating filament supply, but makes conduction/water cooling of the anode block difficult.

3. Dual positive and negative supplies with a common Earth, which reduces insulation requirements, but otherwise has the diasvantages of the other two methods, with none of their advantages.

* Not including specialist flash X-ray tubes, whose mode of operation is rather different.

Re: X-Ray VS Magnetron?
Arcstarter, Sat Oct 09 2010, 08:34PM

That's interesting. Do you mean flash X-ray tubes in general, or only specific kinds of flash X ray tubes? I know the basic theory of operation of flash X ray tubes.

I have a question about making a flash X ray device using an old electron tube rectifier, such as in Plasmatron's site ( ). He, and others, use a marx setup, or something else that provides a large current pulse.

Well, if you have no heater, which is suggested in his site, the voltage drop is very large. My ignition coils kept a voltage drop of around 60kv across my rectifier tube, even though low power. If using a 60kv marx, how would the tube draw any real current? Or, does it not draw much of any current? If i where to heat the filament, why would it produce less X-rays, provided the current from the marx/source was sufficient to sustain a high enough voltage drop?

Re: X-Ray VS Magnetron?
Proud Mary, Sun Oct 10 2010, 12:17AM


I wish I did!


There is no need of Marx or other impulse generator to drive a flash X-ray tube. Simply discharging a capacitor through a tube of suitable geometry will initiate a vacuum breakdown discharge - the flash. See:

Eur. Phys. J. Appl. Phys. 29, 91-97 (2005)
DOI: 10.1051/epjap:2004176
X-rays emission from a compact diode energized by capacitor discharge
M. Zakaullah1, S. Ahmed1, S. Hussain1, M. Afzal1 and A. Waheed2

1 Department of Physics, Quaid-i-Azam University, 45320 Islamabad, Pakistan
2 PINSTECH, PO Box 2151, 44000 Islamabad, Pakistan

Abstract
X-ray emission from a compact diode consisting of a sharp edged cathode and flat anode of copper and lead, energized by simple capacitor discharge is reported. With a sewing machine needle cathode, and lead target, the generation efficiency upto 0.4% is obtained. The efficiency is expected to enhance further with the increase in discharge energy, charging voltage and reducing the parasitic inductance.

Just like a corona discharge in air, field emission is greatest where the electric field is most dense - at sharp points - so the finer the point the greater the field emission will be. This has lead in the last few years to the ultimate in fine points - the carbon nanotube - being used on the cathode of flash X-ray tubes. Such a concentration of field emission together with a sufficient potential difference leads to vacuum breakdown, and a fast current pulse - which is why it is important to have circuit inductance as low as possible, since inductance would slow the pulse down.

The exact nature of 'vacuum breakdown' is still being heavily researched, but suffice it to say it contains elements of spark, arc, and probably quantum tunneling, so I shan't try to explain what I don't myself fully understand.


Let us take the case of a simple thermionic diode rectifier of the type which was used many years ago to rectify the CRT high voltage supply in a TV. In normal operation, with the heater boiling electrons off the cathode, the voltage drop across the diode will be 150V or so, and with such a low potential difference between anode and cathode, no X-rays that can get through the glass wall of the tube will be produced. Now, if the heater fails, the valve will(almost!) stop conducting, and the potential difference across it will rise to the full value of the supply - say 20kV. Now this is enough to cause field emission to break out from sharp edges and points, and the freed electrons will be accelerated towards the anode. Some of the electrons impacting on the anode will produce X-rays, with a small percentage of them having a maximum photon energy of 20keV - the same as the supply voltage.

While the diode may pass a current of say 1.5mA with the heater running in normal operation, it may only pass 30 or 40uA due to field emission, but these electrons, accelerated by the large voltage drop across the valve will produce some X-rays. This was the mode of X-ray production used in cold cathode tubes before the invention of the Coolidge tube (1917) which has a heated cathode.

Flash X-ray mode is more dependent on electrode geometry - the needle cathode and the flat plate anode to enable vacuum breakdown - than it is on anode voltage alone. With a tube of suitable geometry, flash X-ray vacuum breakdown will occur simply by discharging a single low inductance HV capacitor through the tube.

Afterword: The case of X-ray production by colour TV EHT shunt stabiliser triodes - thermionic valves configured to work much like zener diodes acros the HV supply - is rather different to most other cases of X-ray producing valves, in that they produced X-rays during normal operation.

Triodes like 6BK4B and PD500 worked with ~25kV on the anode in typical operation, which was sufficient to generate X-rays capable of penetrating the glass bulb - the media discovery of which lead to alarm and scandal in the 1960s, some of it justified.

This lead to the hasty production of a less hazardous successor to 6BK4B - 6BK4C - which used lead glass, and carried an X-ray hazard warning in the datasheet together with a statement that the valve would not generate more than 1.5mR/hr.

Both 6BK4B and PD500 have formed the basis of many amateur X-ray setups, most often using them in cold cathode mode, where the experimenters have not been able to access or afford dedicated X-ray technology. Needless to say, the absence of a defined focal spot has meant that the images produced are not of the first quality.

Re: X-Ray VS Magnetron?
plazmatron, Sun Oct 10 2010, 07:29PM


When driving a tube in "flash mode", either by using a Marx/Spiral generator/LC inversion circuit, the current drawn by the tube is in fact huge.

During the impulse, field emission occurs explosively at the cathode, leading to vacuum plasma formation. During the short period of plasma formation, thousands of amps can flow.

The exact cause is still a bit of a mystery as Proud Mary said. Even the standard models for ordinary field emission are highly complex and only recently a decent mathematical model was put forth that could explain the goings on at the tip of a single fine point!

Les

Re: X-Ray VS Magnetron?
Conundrum, Wed Jan 10 2018, 09:13AM

The pulsed mode certainly works. Also relevant, depending on the tube some work especially well when only one pin is connnected and the others are left insulated.
I made one using a car sidelight bulb with a particularly well blown (small gap) filament and a shaped electrode around one side where the black coating was thickest. This worked quite well as did applying the HV across the filament and shaped electrode on the +HV side.