Due to the odd nature of my design I thought it'd be best to ask first and see what ya'll think about the precautions I'll eb putting in place. For those who saw my other post detailing my design you'll know it is essentially 2 potential drop accelerators aimed at each other. The biggest problem with this is that it runs on van de graffs so it is very very high voltage (but extremely low current) and is mostly glass. So i'm not sure really what to do. so far I have 30 ft and a foot of concrete and rebar surrounding the whole setup as that is my lab space. I wont be in the room while it's running. Everything is remotely operated so I can manage to be a good distance away. I was stil going to put some lead shielding around everything as well as some borated paraffin for the neutrons. I'm not sure if i'd need extra thick lead because i'm not sure what kind of xrays this is going to kick out. I know normally the xrays energy is proportional to the voltage but i'm not sure if that's still the case with the ultra low amperage. So any thoughts?
For the record the whole reactor is about 2 and a half to 3 feet long and both sides have a foot of glass tubing for the accelerators. I attached a pic so you know what i'm describing.
Potential safety setup
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David D Speck MD
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Re: Potential safety setup
Justin,
What do you figure your total accelerating potentials will be? That will pretty much determine how much shielding you need.
Dave
What do you figure your total accelerating potentials will be? That will pretty much determine how much shielding you need.
Dave
Re: Potential safety setup
I'm not sure to be honest. Im still in the acquiring and designing stage so I can adjust it acordingly. I would like to take it up to 500kev but I'm not sure.
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Dennis P Brown
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Re: Potential safety setup
As a x-ray source dual accelerators could be very dangerous; of course, back-flow electrons are the big issue in these devices and depending on the equipment's ability to prevent that problem (anti-back streaming grid - where is that in your design?), the x-ray danger could be very low to highly dangerous. This threat depends on how effective your anti-back flow system performs it function. Remember, electrons are created by any collisions between protons and atoms and these electrons are then accelerated by the Van de Graaf better than the proton beam.
One foot of concrete and thirty feet distance is overkill but I guess better safe than sorry. Your device (even if it produces 500 kilo-volt x-rays) could be shielded far more simply with a much smaller shield system, by the way.
The neutrons (depending on the flux) are a very different shielding issue (the 1 ft of concrete offers zero protection) and you may or may not need to address that. Still, thirty feet would drop even a high flux 4Pi Steradian source to a very low level. So, as long as the flux is low that should not be an issue for your device (people have fusors with 10^6 sec and that is considered safe.) Again, measure the flux and you will know.
The arrangement of two facing accelerator beams will produce a very trivial amount of direct collisions between the two beams (almost no neutrons) so I hope that is not your goal but rather a center target will be in place. Remember - the accelerator needs low 10^-6 torr (speaking of, I do not see a turbo pump in your image); this is not a fusor so you will not have a gas at a few mircons where 4Pi Steradian interaction space and slow speed semi-shielded ions exist so fusion collisions are 'likely' (at least on a fusor plasma level when it yields a neutron flux in the range of 10^6 neutrons/sec.) A electro-static linear accelerator (ESLA) uses a different approch - a very few high energy ions (10^9 or so deuterons in the beam, most cases) hitting a solid target of some deuterated material (10^21 atoms/cm^3.)
Colliding two beams with such incredibly few ions that have, worse of all, an extremely small 'direct' hit probability to fuse cross-section is extremely unlikely. As such, such an arrangement will provide few, if any measurable interactions.
For this reason, I feel you should rethink your experiment with that device. A solid target works far better in creating a very high flux of fusion events (10^7 or even higher) but such a target will very likely need water cooling depending on the beam current.
By the way, I use a watercooled target in my ESLA; maybe I'll get to irradiate my Pd/deuterium target one day soon. I'm on my third major rebulid of the accelerator's sub-systems; all I can say is, it is dangerous to rethink one's design issues and referance other systems or especially ask advice here - one quickly discovers all errors in their design (me, at least) and then realizes these must be corrected before the machine will ever work at all ...of course this creates new issues and one get's the fun of dealing with these ... lol.
By the way, I would listen to any advice Chris provides very closely; he has experience with real systems - my is mostly just reading.
One foot of concrete and thirty feet distance is overkill but I guess better safe than sorry. Your device (even if it produces 500 kilo-volt x-rays) could be shielded far more simply with a much smaller shield system, by the way.
The neutrons (depending on the flux) are a very different shielding issue (the 1 ft of concrete offers zero protection) and you may or may not need to address that. Still, thirty feet would drop even a high flux 4Pi Steradian source to a very low level. So, as long as the flux is low that should not be an issue for your device (people have fusors with 10^6 sec and that is considered safe.) Again, measure the flux and you will know.
The arrangement of two facing accelerator beams will produce a very trivial amount of direct collisions between the two beams (almost no neutrons) so I hope that is not your goal but rather a center target will be in place. Remember - the accelerator needs low 10^-6 torr (speaking of, I do not see a turbo pump in your image); this is not a fusor so you will not have a gas at a few mircons where 4Pi Steradian interaction space and slow speed semi-shielded ions exist so fusion collisions are 'likely' (at least on a fusor plasma level when it yields a neutron flux in the range of 10^6 neutrons/sec.) A electro-static linear accelerator (ESLA) uses a different approch - a very few high energy ions (10^9 or so deuterons in the beam, most cases) hitting a solid target of some deuterated material (10^21 atoms/cm^3.)
Colliding two beams with such incredibly few ions that have, worse of all, an extremely small 'direct' hit probability to fuse cross-section is extremely unlikely. As such, such an arrangement will provide few, if any measurable interactions.
For this reason, I feel you should rethink your experiment with that device. A solid target works far better in creating a very high flux of fusion events (10^7 or even higher) but such a target will very likely need water cooling depending on the beam current.
By the way, I use a watercooled target in my ESLA; maybe I'll get to irradiate my Pd/deuterium target one day soon. I'm on my third major rebulid of the accelerator's sub-systems; all I can say is, it is dangerous to rethink one's design issues and referance other systems or especially ask advice here - one quickly discovers all errors in their design (me, at least) and then realizes these must be corrected before the machine will ever work at all ...of course this creates new issues and one get's the fun of dealing with these ... lol.
By the way, I would listen to any advice Chris provides very closely; he has experience with real systems - my is mostly just reading.
Re: Potential safety setup
I should have mentioned the target. The dual beams converge on small deuterated target right in the middle. Can't be seen in the picture obviously. I was going to have some sort of grid to deal with the back flow of electrons but I wasn't sure of the best place to put it. Although I was probably going to put it inside the ion sources on the ends, that way they wont get out to begin with. Also I'm just using a diffusion pump because I dont have a turbo pump. Also I just dont want to be in the room to begin with so that's why there's the 30 ft and foot of concrete. I'll be controlling the experiment from a different room to be safe. Also I was thinking of putting some borated paraffin sheets near the target to absorb the majority of the neutrons. Also the ion source has a magnetic coil around it to extract the ions. This should help keep the electrons inside the source and then a grid will be present to collect them and get rid of them.
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Richard Hull
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Re: Potential safety setup
The diff pump might drag you down to extinction and allow the Van Degraff's to work at or near their potential. If so, then you can have some very penetrating x-rays come of that thing. With no way to meter the current or voltage, you are taking a chance, for sure.
It you can't get to near extinction the device will load the devices down to where little or nothing will happen. I haven't seen the electrostatic machines so that is an issue I can't comment on.
Richard Hull
It you can't get to near extinction the device will load the devices down to where little or nothing will happen. I haven't seen the electrostatic machines so that is an issue I can't comment on.
Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
Re: Potential safety setup
To start I'll only be running at 100kev so if memory servers the protection I outlined should be sufficient. I'm however more worried about what happens when the power is brought any higher than that. That said I'm no expert so if i'm wrong PLEASE correct me.
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Dennis P Brown
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Re: Potential safety setup
If you are using a diffusion pump, then you must have a cold trap; otherwise, the oil back flow will kill your vacuum. With two accelerators, the target will need a grid for each side that is irreadiated. The grid is located in front of the target and fairly close - that is where 99.999999% of the electrons will be produced. With a good grid, the x-ray danger is dramaticly reduced from what I understand.
A quick safety design comment: if you have an easy and rapid way to kill power to the the battery for that HV source for the main 'gun', then that will fully kill all radiation even if the Van de Graaf is running. See the Sci Am design and how that works (they did not have an electron anti-back flow grid.) People here use them and its in some of the threads. Until I test mine, I do not feel it would be proper or safe to share that design.
A quick safety design comment: if you have an easy and rapid way to kill power to the the battery for that HV source for the main 'gun', then that will fully kill all radiation even if the Van de Graaf is running. See the Sci Am design and how that works (they did not have an electron anti-back flow grid.) People here use them and its in some of the threads. Until I test mine, I do not feel it would be proper or safe to share that design.