Hello:
I just stumbled on these old notes from the time of Cockcroft and Walton. It seems like a very simple way to get to .5 - 1.5 MEV energy levels. I was able to confirm that this principal worked for X-ray generation. What has me curious is: If it works for positive ions? Especially like in the tandem acceleration example.
This approach would seem to have a lot of potential for fusion reactions, especially for those requiring higher energies like B11 etc. I am just curious to learn others thoughts about this old RF driven concept. Another plus is that it is very simple in theory, and it would lend itself for amateur construction just like a fusor. Thanks.....
Resonant Accelerator Fusion
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lutzhoffman
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Resonant Accelerator Fusion
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Chris Bradley
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Re: Resonant Accelerator Fusion
Not sure I would ever call that a 'resonant accelerator'. It's a tandem acceleration, plain and simple. (Isn't it? Am I missing something?)
Self-enforcing feedback resonances are the ultimate 'leverage' that nature can give us and I reckon the most efficient form of anything will use such principles (whether it is know they do, or whether it is a hidden, underlying behaviour). Unfortunately, the only self-enforcing feedback resonances here are in the power supply, not in the ion acceleration.
It would also be horrendously inefficient for 'fusor-ing'. Efficiency is never much of a concern in atom smashing experiments.
Self-enforcing feedback resonances are the ultimate 'leverage' that nature can give us and I reckon the most efficient form of anything will use such principles (whether it is know they do, or whether it is a hidden, underlying behaviour). Unfortunately, the only self-enforcing feedback resonances here are in the power supply, not in the ion acceleration.
It would also be horrendously inefficient for 'fusor-ing'. Efficiency is never much of a concern in atom smashing experiments.
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Richard Hull
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Re: Resonant Accelerator Fusion
I would have thought in-efficiency in fusing was a foregone conclusion. I would be willing to trade 10 KW outta' the wall outlet for a solid 200 micro joules of fusion based neuts!
Of course, there are many missions due to many battles in progress.
Richard Hull
Of course, there are many missions due to many battles in progress.
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
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Carl Willis
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Re: Resonant Accelerator Fusion
Lutz,
This approach is taken to accelerate ions.
Modern drift-tube RF linacs broadly use this principle as well, though the resonant structures do not take the shape of coils and the exciting frequencies tend to be in the UHF band. Many superconducting heavy-ion linacs (an example being the small one at the Macdonald Laboratory at KSU) use cells that are based on either a single drift tube mounted on the end of a quarter-wave resonator, or two drift tubes mounted on the ends of a half-wave resonator. Frequency varies, but the FM broadcast band is popular. The RF drift-tube ion linac is generally not used to accelerate beams entering with less than a subtantial fraction of 1 MeV / u.
One can also find the same integral step-up resonant transformer concept at work in many modern DC linacs.
-Carl
This approach is taken to accelerate ions.
Modern drift-tube RF linacs broadly use this principle as well, though the resonant structures do not take the shape of coils and the exciting frequencies tend to be in the UHF band. Many superconducting heavy-ion linacs (an example being the small one at the Macdonald Laboratory at KSU) use cells that are based on either a single drift tube mounted on the end of a quarter-wave resonator, or two drift tubes mounted on the ends of a half-wave resonator. Frequency varies, but the FM broadcast band is popular. The RF drift-tube ion linac is generally not used to accelerate beams entering with less than a subtantial fraction of 1 MeV / u.
One can also find the same integral step-up resonant transformer concept at work in many modern DC linacs.
-Carl
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Chris Trent
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Re: Resonant Accelerator Fusion
Looks to me like a plain old tuned coil arrangement, nicely tucked into vacuum to resolve insulation issues.
I don't think you could power a fusor with this, but if you want to do some simple beam target experiments it sure looks a lot easier than building a full fledged Lineac.
I don't think you could power a fusor with this, but if you want to do some simple beam target experiments it sure looks a lot easier than building a full fledged Lineac.
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Doug Coulter
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Re: Resonant Accelerator Fusion
Lutz,
I've had this one floating around in my mind for quite awhile, it could be a useful approach for fusors and it solves some insulation problems that get nasty at the higher voltages when you have to put the HV through from air into the tank. However, you do get a time vs energy curve due to the non DC aspect of this that you had said you didn't want in your setup.
You should know that Carl works for an outfit that makes linacs -- you're getting the straight skinny there.
I have some books, unfortunately not in digital form, that describe the drift tube accelerator approach in some detail, complete with all design math. The issues are pretty simple, actually. For non relativistic particles each stage has to get longer for a given frequency drive to keep things in phase, as non relativistic particles actually do go noticeably faster when you add energy to them. Thus, for many stages the thing gets long. As light ions go a lot faster than heavy ones for a given energy, doing this with light ions is kind of the worst case -- longer drift tubes needed for a given drive frequency. "Back in the day" when they couldn't get to GHz at high power, that was the limit, and most drift tube linacs that made any decent energy did so with heavy ions and long total lengths.
As Carl points out indirectly, the modern designs use resonant cavities to get to higher frequencies and thus can't change length on a per cavity basis (without quite a lot of fiddling problems) for non relativistic ions, so they don't do that -- they use high enough injection energies to avoid that need in general, or greatly reduce it.
The problem with using this as a fusor type fast accelerator is that we're currently doing that in enough gas that putting the final stepup coil in the tank will result in breakdowns across the coil winding themselves. With a linac using an ion source and differential pumping to keep the acceleration tube clear of too much gas, this can work, otherwise it's just moving the problem to a place that's harder to get at and fix. Note that it doesn't have to be done as a stepup transformer as such, but could be the inductor part of a more modern Pi network, as found in nearly all ham transmitters, with the grid as the output C to ground. The nice thing there is you could drive it with low voltage high current HF, which is easy to make go through a cheap feedthrough.
This may be workable at the DD energies, but tough to get really high energies with due to the gas breakdown troubles (unless you're willing to have differential pumping and all that entails, which this group tends to eschew for pretty good reason$).
Does this mean I won't try it just for the heck of it? Nope, already have the stuff and it's in the plan, but for what I want to do, a sine wave isn't the right thing....so we'll see how much I put effort into it. It's on my list of things to do someday -- which is a longer list than my remaining expected lifetime already (but it's higher on the list than a lot of other things).
I'll have to save that paper in my digital library, it's one I didn't have already, thanks!
I've had this one floating around in my mind for quite awhile, it could be a useful approach for fusors and it solves some insulation problems that get nasty at the higher voltages when you have to put the HV through from air into the tank. However, you do get a time vs energy curve due to the non DC aspect of this that you had said you didn't want in your setup.
You should know that Carl works for an outfit that makes linacs -- you're getting the straight skinny there.
I have some books, unfortunately not in digital form, that describe the drift tube accelerator approach in some detail, complete with all design math. The issues are pretty simple, actually. For non relativistic particles each stage has to get longer for a given frequency drive to keep things in phase, as non relativistic particles actually do go noticeably faster when you add energy to them. Thus, for many stages the thing gets long. As light ions go a lot faster than heavy ones for a given energy, doing this with light ions is kind of the worst case -- longer drift tubes needed for a given drive frequency. "Back in the day" when they couldn't get to GHz at high power, that was the limit, and most drift tube linacs that made any decent energy did so with heavy ions and long total lengths.
As Carl points out indirectly, the modern designs use resonant cavities to get to higher frequencies and thus can't change length on a per cavity basis (without quite a lot of fiddling problems) for non relativistic ions, so they don't do that -- they use high enough injection energies to avoid that need in general, or greatly reduce it.
The problem with using this as a fusor type fast accelerator is that we're currently doing that in enough gas that putting the final stepup coil in the tank will result in breakdowns across the coil winding themselves. With a linac using an ion source and differential pumping to keep the acceleration tube clear of too much gas, this can work, otherwise it's just moving the problem to a place that's harder to get at and fix. Note that it doesn't have to be done as a stepup transformer as such, but could be the inductor part of a more modern Pi network, as found in nearly all ham transmitters, with the grid as the output C to ground. The nice thing there is you could drive it with low voltage high current HF, which is easy to make go through a cheap feedthrough.
This may be workable at the DD energies, but tough to get really high energies with due to the gas breakdown troubles (unless you're willing to have differential pumping and all that entails, which this group tends to eschew for pretty good reason$).
Does this mean I won't try it just for the heck of it? Nope, already have the stuff and it's in the plan, but for what I want to do, a sine wave isn't the right thing....so we'll see how much I put effort into it. It's on my list of things to do someday -- which is a longer list than my remaining expected lifetime already (but it's higher on the list than a lot of other things).
I'll have to save that paper in my digital library, it's one I didn't have already, thanks!
Why guess when you can know? Measure!
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lutzhoffman
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Re: Resonant Accelerator Fusion
Hello:
Reference the comments:
Yup, I should have called it something different, I agree.
I think the comments by Chris Trent do a pretty good job in pining down where my mind was at, when I stumbled on to this old design. Carl did a great job also in tying it in to modern reality by showing how far it has come.
This design was just one of those "things", or "ideas" that was simply elegant in its simplicity, and design, when what it potentialy can, or could do, is taken into account.
In simple terms I do not have any application, or particular use in mind for this design, yet I was intrigued, and fascinated enough by it, to warrant saving it in the design tool box for some possible future use, kind of along the lines of what Doug said.
It just seems like something so simple to build, which can get to these kind of energy levels without a big pressure chamber, or thousands of dollars worth of diodes, and capacitors, has just got to be good for something, the million dollar question what?
Reference the comments:
Yup, I should have called it something different, I agree.
I think the comments by Chris Trent do a pretty good job in pining down where my mind was at, when I stumbled on to this old design. Carl did a great job also in tying it in to modern reality by showing how far it has come.
This design was just one of those "things", or "ideas" that was simply elegant in its simplicity, and design, when what it potentialy can, or could do, is taken into account.
In simple terms I do not have any application, or particular use in mind for this design, yet I was intrigued, and fascinated enough by it, to warrant saving it in the design tool box for some possible future use, kind of along the lines of what Doug said.
It just seems like something so simple to build, which can get to these kind of energy levels without a big pressure chamber, or thousands of dollars worth of diodes, and capacitors, has just got to be good for something, the million dollar question what?