X-ray :D
Linas, Sat Dec 22 2007, 09:16PMhi
i have very big x-ray tube, and have 200Kv sstc, is it posible make good x ray machine??
and how tu know, how many pm or nm (nanometre)electromagnetic radiation ?
some photos
Re: X-ray :D
Shaun, Sun Dec 23 2007, 04:17AM
I'm pretty sure X-ray tubes need DC, not HF AC. Plus they are usually fired by a large capacitive discharge, producing a high-energy burst of X-rays. You will probably get some radiation with that tube on an SSTC, but I doubt it will be significant.
Shaun, Sun Dec 23 2007, 04:17AM
I'm pretty sure X-ray tubes need DC, not HF AC. Plus they are usually fired by a large capacitive discharge, producing a high-energy burst of X-rays. You will probably get some radiation with that tube on an SSTC, but I doubt it will be significant.
Re: X-ray :D
Dr. Dark Current, Sun Dec 23 2007, 10:31AM
I don't know how much voltage it needs but 80-100kv is achievable with a DC flyback
Dr. Dark Current, Sun Dec 23 2007, 10:31AM
I don't know how much voltage it needs but 80-100kv is achievable with a DC flyback
Re: X-ray :D
c4r0, Sun Dec 23 2007, 12:14PM
I think driving real x-ray tube (especially heated cathode type) directly from SSTC is not a good idea. To get preety good radiograms you need at least 50kV (medical diagnostic x-ray machines usually uses about 50-100kV range). DC would be the best, but actually x-ray tube is a vacuum diode, so it will self-rectify the current. In some x-ray machines (in my x-ray machine too) this self-rectifying is used and x-ray tube is connected directly to the HV mains transformer winding, but it's 50Hz, not hundreds of kHz like in SSTC. Anyway, you can try it, but you absolutely need a geiger counter
c4r0, Sun Dec 23 2007, 12:14PM
I think driving real x-ray tube (especially heated cathode type) directly from SSTC is not a good idea. To get preety good radiograms you need at least 50kV (medical diagnostic x-ray machines usually uses about 50-100kV range). DC would be the best, but actually x-ray tube is a vacuum diode, so it will self-rectify the current. In some x-ray machines (in my x-ray machine too) this self-rectifying is used and x-ray tube is connected directly to the HV mains transformer winding, but it's 50Hz, not hundreds of kHz like in SSTC. Anyway, you can try it, but you absolutely need a geiger counter
Re: X-ray :D
Linas, Sun Dec 23 2007, 12:39PM
how to detect x-ray in house ?
Linas, Sun Dec 23 2007, 12:39PM
how to detect x-ray in house ?
Re: X-ray :D
ConKbot of Doom, Sun Dec 23 2007, 03:55PM
Some of the X-ray machines Ive seen at work use 2 capacitors, each about the same hight as and 3/4 the diameter of a 55 gallon barrel.
ConKbot of Doom, Sun Dec 23 2007, 03:55PM
Shaun wrote ...
I'm pretty sure X-ray tubes need DC, not HF AC. Plus they are usually fired by a large capacitive discharge, producing a high-energy burst of X-rays. You will probably get some radiation with that tube on an SSTC, but I doubt it will be significant.
I'm pretty sure X-ray tubes need DC, not HF AC. Plus they are usually fired by a large capacitive discharge, producing a high-energy burst of X-rays. You will probably get some radiation with that tube on an SSTC, but I doubt it will be significant.
Some of the X-ray machines Ive seen at work use 2 capacitors, each about the same hight as and 3/4 the diameter of a 55 gallon barrel.
Re: X-ray :D
c4r0, Sun Dec 23 2007, 04:33PM
). Or you can make one just like Uzzors did: 
c4r0, Sun Dec 23 2007, 04:33PM
Linas wrote ...
how to detect x-ray in house ?
With geiger counter or suitable ionising chamber. I'm preety sure that you can easily find a cheap geiger counter on internet auction in Lithuania, just be patient (i hope you have an internet auction website there how to detect x-ray in house ?
). Or you can make one just like Uzzors did: Re: X-ray :D
Linas, Sun Dec 23 2007, 04:51PM
no :(
Linas, Sun Dec 23 2007, 04:51PM
c4r0 wrote ...
). Uzzors did:
Linas wrote ...
how to detect x-ray in house ?
I'm preety sure that you can easily find a cheap geiger counter on internet auction in Lithuania, just be patient (i hope you have an internet auction website there how to detect x-ray in house ?
). Uzzors did: no :(Re: X-ray :D
uzzors2k, Sun Dec 23 2007, 09:06PM
Why not? It works okay.
I've actually been doing some x-ray experiments lately, but so far the radiation has been pretty weak. I haven't seen any fluorescence yet, but my geiger counter will overflow when brought within a few cm of the tube. This is with the 0.4R/h GM tube... At least it proves the geiger counter works, and x-rays are present! If only I had a real x-ray tube and not some crummy HV rectifiers.
As for driving your tube (which you are lucky to have) I think your TC would work alright, at least to see that it works. As said earlier the tube will rectify anyway, and being a tube it can handle the frequency easily.
uzzors2k, Sun Dec 23 2007, 09:06PM
Why not? It works okay.
I've actually been doing some x-ray experiments lately, but so far the radiation has been pretty weak. I haven't seen any fluorescence yet, but my geiger counter will overflow when brought within a few cm of the tube. This is with the 0.4R/h GM tube... At least it proves the geiger counter works, and x-rays are present! If only I had a real x-ray tube and not some crummy HV rectifiers.
As for driving your tube (which you are lucky to have) I think your TC would work alright, at least to see that it works. As said earlier the tube will rectify anyway, and being a tube it can handle the frequency easily.
Re: X-ray :D
Proud Mary, Wed Jan 16 2008, 11:33PM
Unless they are specifically designed for detecting the low energy X-rays likely to be produced here, GM tubes are not at all a good way to detect them.
X-ray sensitive GM tubes are constructed much like a longer version of an end-window alpha tube, but with a thicker mica window. A heavy fill gas like argon or krypton is usually used, and at a much higher pressure than in other types of GM tubes - typically 600 - 650 torr.
Some 'general purpose' beta/gamma GM tubes will fail to detect low-energy X-rays altogether, and none but those specially designed for the job should be relied upon for a meaningful indication of dose.
Low energy X-rays are the most hazardous to human health, so one can't afford to not detect them!
Proud Mary, Wed Jan 16 2008, 11:33PM
Unless they are specifically designed for detecting the low energy X-rays likely to be produced here, GM tubes are not at all a good way to detect them.
X-ray sensitive GM tubes are constructed much like a longer version of an end-window alpha tube, but with a thicker mica window. A heavy fill gas like argon or krypton is usually used, and at a much higher pressure than in other types of GM tubes - typically 600 - 650 torr.
Some 'general purpose' beta/gamma GM tubes will fail to detect low-energy X-rays altogether, and none but those specially designed for the job should be relied upon for a meaningful indication of dose.
Low energy X-rays are the most hazardous to human health, so one can't afford to not detect them!
Re: X-ray :D
Proud Mary, Thu Jan 17 2008, 12:56AM
There is no reason in principle why an X-ray tube could not be driven by a Tesla coil. In the early days of X-radiography, induction coils were widely used to excite X-ray tubes, and AC machines are still in use today, especially for portable work where the weight and size of the machine must be kept to a minimum.
I would forsee your biggest problem being in the matching of the coil to the load. An indirectly heated X-ray tube of the type shown in your picture will draw a sizeable anode current [have a relatively low impedance] and detune your coil to the extent that little power is produced.
What is to be done? You may get best results by running your X-ray tube under starvation conditions. Run the heater from a variable current controlled source, so you are able to gradually turn up the heater current until emission just begins. You may then increase it (so increasing the tube anode current) until you have reached the maximum anode current your Tesla can provide when loaded.
You might make things easier for yourself by first setting up your rig with the coil output wired to the tube anode, and tuning the coil (but at much reduced power) to get maximum tesla output with the unheated tube as the (largely capacative) load. Once you have achieved this, you might then start tweaking up the heater current until the tube starts to draw current.
Thermionic devices don't like it if you apply too much juice before they are warmed up, so I'd suggest only increasing both heater and anode currents in small increments until conditions are stable and X-ray emission starts.
As for the wavelength, the greater the excitation voltage, the smaller will be the value of the minimum wavelength limit. This is known as the Duane Hunt Relationship.
If we imagine that you have matched your coil to the tube anode and your coil is actually able to deliver 100KV to the tube, then from the Duane Hunt Law we can show that the mimimum wavelength produced will be 0.0124 nm.
Finally, you will most likely get some cold cathode emission from the tube if you apply anode voltage with no heater current, so don't assume it is safe just because it isn't heated. The impedance of the unheated tube will be very much higher, so there will be less voltage drop across the tube, and hence more energetic X-rays, though a lot less of em!
Proud Mary, Thu Jan 17 2008, 12:56AM
Linas wrote ...
i
i have very big x-ray tube, and have 200Kv sstc, is it posible make good x ray machine??
and how tu know, how many pm or nm (nanometre)electromagnetic radiation ?
i
i have very big x-ray tube, and have 200Kv sstc, is it posible make good x ray machine??
and how tu know, how many pm or nm (nanometre)electromagnetic radiation ?
There is no reason in principle why an X-ray tube could not be driven by a Tesla coil. In the early days of X-radiography, induction coils were widely used to excite X-ray tubes, and AC machines are still in use today, especially for portable work where the weight and size of the machine must be kept to a minimum.
I would forsee your biggest problem being in the matching of the coil to the load. An indirectly heated X-ray tube of the type shown in your picture will draw a sizeable anode current [have a relatively low impedance] and detune your coil to the extent that little power is produced.
What is to be done? You may get best results by running your X-ray tube under starvation conditions. Run the heater from a variable current controlled source, so you are able to gradually turn up the heater current until emission just begins. You may then increase it (so increasing the tube anode current) until you have reached the maximum anode current your Tesla can provide when loaded.
You might make things easier for yourself by first setting up your rig with the coil output wired to the tube anode, and tuning the coil (but at much reduced power) to get maximum tesla output with the unheated tube as the (largely capacative) load. Once you have achieved this, you might then start tweaking up the heater current until the tube starts to draw current.
Thermionic devices don't like it if you apply too much juice before they are warmed up, so I'd suggest only increasing both heater and anode currents in small increments until conditions are stable and X-ray emission starts.
As for the wavelength, the greater the excitation voltage, the smaller will be the value of the minimum wavelength limit. This is known as the Duane Hunt Relationship.
If we imagine that you have matched your coil to the tube anode and your coil is actually able to deliver 100KV to the tube, then from the Duane Hunt Law we can show that the mimimum wavelength produced will be 0.0124 nm.
Finally, you will most likely get some cold cathode emission from the tube if you apply anode voltage with no heater current, so don't assume it is safe just because it isn't heated. The impedance of the unheated tube will be very much higher, so there will be less voltage drop across the tube, and hence more energetic X-rays, though a lot less of em!
Re: X-ray :D
plazmatron, Thu Jan 31 2008, 09:54PM
Nice tube!
Personally I would avoid the tesla coil approach, since results can be unpredictable.
A much better approach would be a ZVS driven flyback (b&w ac type) with an external multiplier. If you are unable to rotate the anode, you need to limit the anode current to under 5mA.
Looking at the tube, I'm guessing you could probably get away with running in air upto 60 kV, after that you will have to sink it in oil.
plazmatron, Thu Jan 31 2008, 09:54PM
Nice tube!
Personally I would avoid the tesla coil approach, since results can be unpredictable.
A much better approach would be a ZVS driven flyback (b&w ac type) with an external multiplier. If you are unable to rotate the anode, you need to limit the anode current to under 5mA.
Looking at the tube, I'm guessing you could probably get away with running in air upto 60 kV, after that you will have to sink it in oil.
Re: X-ray :D
atomicthumbs, Fri Feb 01 2008, 06:41PM
Sudden appearances of malignant growths.
And geiger counters.
atomicthumbs, Fri Feb 01 2008, 06:41PM
Linas wrote ...
how to detect x-ray in house ?
how to detect x-ray in house ?
Sudden appearances of malignant growths.
And geiger counters.
Re: X-ray :D
plazmatron, Tue Feb 05 2008, 10:40PM
I checked my lowest energy x-ray source (10 keV) today, with a standard Civil Defense CD V700 geiger counter. Even with the counter set on the highest range it will happily peg the meter!
Whilst the reading from a common geiger counter cannot be relied upon, it will at least give a positive indication of the presence of x-rays.
CD V700 Geiger counters can be had off of eBay, at a very moderate cost, and I encourage anyone working with radiation, or suspecting that something may be emitting radiation, to purchase one.
Leslie
plazmatron, Tue Feb 05 2008, 10:40PM
Harry wrote ...
Some 'general purpose' beta/gamma GM tubes will fail to detect low-energy X-rays altogether, and none but those specially designed for the job should be relied upon for a meaningful indication of dose.
Low energy X-rays are the most hazardous to human health, so one can't afford to not detect them!
Some 'general purpose' beta/gamma GM tubes will fail to detect low-energy X-rays altogether, and none but those specially designed for the job should be relied upon for a meaningful indication of dose.
Low energy X-rays are the most hazardous to human health, so one can't afford to not detect them!
I checked my lowest energy x-ray source (10 keV) today, with a standard Civil Defense CD V700 geiger counter. Even with the counter set on the highest range it will happily peg the meter!
Whilst the reading from a common geiger counter cannot be relied upon, it will at least give a positive indication of the presence of x-rays.
CD V700 Geiger counters can be had off of eBay, at a very moderate cost, and I encourage anyone working with radiation, or suspecting that something may be emitting radiation, to purchase one.
Leslie
Re: X-ray :D
Proud Mary, Wed Feb 06 2008, 12:47AM
Is that with the 6993 GM tube, Leslie?
Proud Mary, Wed Feb 06 2008, 12:47AM
Is that with the 6993 GM tube, Leslie?
Re: X-ray :D
Conundrum, Wed Feb 06 2008, 07:48PM
Hmm. Well, I discovered by accident that an off-the-shelf B&Q el cheapo CMOS camera makes a fairly nice spinthariscope, using Am-241 source and a thin mica window.
Might be worth trying this with a thin (beryllium?) window to exclude light, or (my own method) silver paint coated mica from a heatsink, cut down to minimal thickness. Pyrolytic graphite might work just as well being pure carbon, and is simpler to pare down (you can sand it!) :)
If anyone does get this working please let me know as my lab is currently in a mess.
regards, -A
"Bother" said Pooh, as he generated a black hole at the LHC...
Conundrum, Wed Feb 06 2008, 07:48PM
Harry wrote ...
Unless they are specifically designed for detecting the low energy X-rays likely to be produced here, GM tubes are not at all a good way to detect them.
X-ray sensitive GM tubes are constructed much like a longer version of an end-window alpha tube, but with a thicker mica window. A heavy fill gas like argon or krypton is usually used, and at a much higher pressure than in other types of GM tubes - typically 600 - 650 torr.
Some 'general purpose' beta/gamma GM tubes will fail to detect low-energy X-rays altogether, and none but those specially designed for the job should be relied upon for a meaningful indication of dose.
Low energy X-rays are the most hazardous to human health, so one can't afford to not detect them!
Unless they are specifically designed for detecting the low energy X-rays likely to be produced here, GM tubes are not at all a good way to detect them.
X-ray sensitive GM tubes are constructed much like a longer version of an end-window alpha tube, but with a thicker mica window. A heavy fill gas like argon or krypton is usually used, and at a much higher pressure than in other types of GM tubes - typically 600 - 650 torr.
Some 'general purpose' beta/gamma GM tubes will fail to detect low-energy X-rays altogether, and none but those specially designed for the job should be relied upon for a meaningful indication of dose.
Low energy X-rays are the most hazardous to human health, so one can't afford to not detect them!
Hmm. Well, I discovered by accident that an off-the-shelf B&Q el cheapo CMOS camera makes a fairly nice spinthariscope, using Am-241 source and a thin mica window.
Might be worth trying this with a thin (beryllium?) window to exclude light, or (my own method) silver paint coated mica from a heatsink, cut down to minimal thickness. Pyrolytic graphite might work just as well being pure carbon, and is simpler to pare down (you can sand it!) :)
If anyone does get this working please let me know as my lab is currently in a mess.
regards, -A
"Bother" said Pooh, as he generated a black hole at the LHC...
Re: X-ray :D
plazmatron, Wed Feb 06 2008, 11:45PM
Yep, thats with the original 6993 tube (beta shield open).
plazmatron, Wed Feb 06 2008, 11:45PM
Yep, thats with the original 6993 tube (beta shield open).
Re: X-ray :D
Proud Mary, Sat Feb 09 2008, 05:00PM
For anyone who doesn't know of it already, the Rad Pro Calculator For Desk Top PCs (freeware) allows you to enter X-ray tube voltage, tube current, a variety of metal filters of graduated thickness, and a variety of shielding materials, to estimate the dose rate at a given distance.
It can do a lot of other interesting things besides.
Proud Mary, Sat Feb 09 2008, 05:00PM
For anyone who doesn't know of it already, the Rad Pro Calculator For Desk Top PCs (freeware) allows you to enter X-ray tube voltage, tube current, a variety of metal filters of graduated thickness, and a variety of shielding materials, to estimate the dose rate at a given distance.
It can do a lot of other interesting things besides.
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