particle accelerators
father dest, Thu Aug 08 2019, 06:37PMthere is wonderful forum about fusors on the net -
maybe somebody of u guys know something as wonderful, but about electron accelerators instead? especially like microtrons and rf linacs, with theory/construction/results sections. or not so wonderful, but still good read.
am wondering what will be easier to build at home, for about 2-5 MeV or so, 0.1 ma average beam current.
Re: particle accelerators
jpsmith123, Sat Aug 10 2019, 11:53PM
I've not built anything (yet at least), but I did look into it a little bit.
An RF linear accelerator or a microtron would be a real challenge and the magnetron and associated power supply would probably be very costly.
I came to the conclusion that a voltage-scaled-up version of the "multibeam accelerator" described by G.V. Dolbilov et al. might be one approach (there are a few other possibilities, IMO).
This design eliminates the problem of a big and bulky vacuum feedthrough insulator and associated problems.
This device apparently uses a multi-turn primary driven with 500 volt pulses at 18 khz or something like that. But to scale up the voltage without making it too big, I think you'd need to drive the primary at a much higher voltage with a very short pulse (sub-microsecond), and use a lower turns ratio.
I think you could operate a graphite cathode in an explosive emission mode so you wouldn't need the big mosaic cathode, the downside would be it would need more maintenance.
jpsmith123, Sat Aug 10 2019, 11:53PM
I've not built anything (yet at least), but I did look into it a little bit.
An RF linear accelerator or a microtron would be a real challenge and the magnetron and associated power supply would probably be very costly.
I came to the conclusion that a voltage-scaled-up version of the "multibeam accelerator" described by G.V. Dolbilov et al. might be one approach (there are a few other possibilities, IMO).
This design eliminates the problem of a big and bulky vacuum feedthrough insulator and associated problems.
This device apparently uses a multi-turn primary driven with 500 volt pulses at 18 khz or something like that. But to scale up the voltage without making it too big, I think you'd need to drive the primary at a much higher voltage with a very short pulse (sub-microsecond), and use a lower turns ratio.
I think you could operate a graphite cathode in an explosive emission mode so you wouldn't need the big mosaic cathode, the downside would be it would need more maintenance.
father dest wrote ...
there is wonderful forum about fusors on the net -
maybe somebody of u guys know something as wonderful, but about electron accelerators instead? especially like microtrons and rf linacs, with theory/construction/results sections. or not so wonderful, but still good read.
am wondering what will be easier to build at home, for about 2-5 MeV or so, 0.1 ma average beam current.
there is wonderful forum about fusors on the net -
maybe somebody of u guys know something as wonderful, but about electron accelerators instead? especially like microtrons and rf linacs, with theory/construction/results sections. or not so wonderful, but still good read.
am wondering what will be easier to build at home, for about 2-5 MeV or so, 0.1 ma average beam current.
Re: particle accelerators
father dest, Sun Aug 11 2019, 06:50AM
thnx for the info. need time too look into all this more carefully, but i found other work of this dude, like
is this a tesla coil?
with sectioned bifilar secondary?
as for the old ex tesla coiler things are starting to get very interesting for me from this point
father dest, Sun Aug 11 2019, 06:50AM
thnx for the info. need time too look into all this more carefully, but i found other work of this dude, like
is this a tesla coil?
with sectioned bifilar secondary?
as for the old ex tesla coiler things are starting to get very interesting for me from this point
Re: particle accelerators
jpsmith123, Sun Aug 11 2019, 04:27PM
I would call the "Multibeam Accelerator" that I linked to in my first comment a type of Tesla coil based accelerator since it has an external primary winding and a resonant secondary.
(BTW I've often wondered what material is used for the outer housing since it would have to be non-conducting, mechanically strong and vacuum compatible. But I could never find a detailed description of this device).
Also, I've seen a description of another Tesla coil based electron accelerator built in Russia called the RIUS-5 which could produce a 5 MV electron beam, and for which the secondary voltage ws said to reach 7 or 8 MV or something like that. But that machine is big and bulky.
Anyway, it seems the device described in the patent you referred to is not a Tesla coil but something akin to a helical resonator; or the more I think about it, a type of quarter wave transformer.
Since the device (if I understand correctly) does not use a single layer helical coil but a bunch of discrete presumably multilayer coils connected in series, he doesn't describe it as a "helical" anything but uses the phrase "coaxial delay line."
This would be the low frequency equivalent of a quarter wave transformer made out of coaxial cable, IMO, which is driven at the resonant frequency by a generator at one end, and is loaded at the HV end by an electron beam diode.
I've never built anything like this so I can't speak from experience, but I am guessing it would be difficult to reach a multi-megavolt output using this approach in anything of a practical size.
With the transistors available today I think you could operate at a frequency significantly higher than the patent suggests, so you could probably use a single layer helical coil instead of many discrete multi-layer coils in series. And I imagine you'd want to design and build it to get the Q as high as possible.
The main problem I see is the risk of HV breakdown in trying to put a few megavolts across a single accelerating gap with a relatively low frequency CW drive - in anything of a practical size.
I think you'd have to build a prototype to see what kind of voltage you can get before breakdown, and then you could experiment with things like magnetic insulation.
In the link below is an example of a Tesla transformer that's used to generate 2.5 MV pulses. Although the paper doesn't go into very much detail, I think the transformer may be capable of going significantly higher than that. The transformer is roughly the same size as that of the "multibeam accelerator" yet it produces a much higher voltage. IMO this is because it is driven with fast HV pulses using a single turn primary.
jpsmith123, Sun Aug 11 2019, 04:27PM
I would call the "Multibeam Accelerator" that I linked to in my first comment a type of Tesla coil based accelerator since it has an external primary winding and a resonant secondary.
(BTW I've often wondered what material is used for the outer housing since it would have to be non-conducting, mechanically strong and vacuum compatible. But I could never find a detailed description of this device).
Also, I've seen a description of another Tesla coil based electron accelerator built in Russia called the RIUS-5 which could produce a 5 MV electron beam, and for which the secondary voltage ws said to reach 7 or 8 MV or something like that. But that machine is big and bulky.
Anyway, it seems the device described in the patent you referred to is not a Tesla coil but something akin to a helical resonator; or the more I think about it, a type of quarter wave transformer.
Since the device (if I understand correctly) does not use a single layer helical coil but a bunch of discrete presumably multilayer coils connected in series, he doesn't describe it as a "helical" anything but uses the phrase "coaxial delay line."
This would be the low frequency equivalent of a quarter wave transformer made out of coaxial cable, IMO, which is driven at the resonant frequency by a generator at one end, and is loaded at the HV end by an electron beam diode.
I've never built anything like this so I can't speak from experience, but I am guessing it would be difficult to reach a multi-megavolt output using this approach in anything of a practical size.
With the transistors available today I think you could operate at a frequency significantly higher than the patent suggests, so you could probably use a single layer helical coil instead of many discrete multi-layer coils in series. And I imagine you'd want to design and build it to get the Q as high as possible.
The main problem I see is the risk of HV breakdown in trying to put a few megavolts across a single accelerating gap with a relatively low frequency CW drive - in anything of a practical size.
I think you'd have to build a prototype to see what kind of voltage you can get before breakdown, and then you could experiment with things like magnetic insulation.
In the link below is an example of a Tesla transformer that's used to generate 2.5 MV pulses. Although the paper doesn't go into very much detail, I think the transformer may be capable of going significantly higher than that. The transformer is roughly the same size as that of the "multibeam accelerator" yet it produces a much higher voltage. IMO this is because it is driven with fast HV pulses using a single turn primary.
Re: particle accelerators
father dest, Sun Aug 11 2019, 09:36PM
this is rius-5
a 40ns low repetition rate multi kiloampere device - not what i want. on the other hand this is relus-5
rf driven linac with a very compact accelerating srtucture, like this one
coz u don't need an insulation for full output voltage/energy - that's what i want. and that's why i think all those "tesla" like devices are bs for home builders. and that multi beam device from your first post too - how is it different? it's for multi kw tasks basically, hence more than one beam, but i need 5 times more energy - not the average power. so microtrons/other cyclical systems are the way to go.
i've found even more interesting paper from the same author, at first glance atleast
never saw such a concept before. there is an english version
father dest, Sun Aug 11 2019, 09:36PM
jpsmith123 wrote ...
Also, I've seen a description of another Tesla coil based electron accelerator built in Russia called the RIUS-5 which could produce a 5 MV electron beam, and for which the secondary voltage ws said to reach 7 or 8 MV or something like that. But that machine is big and bulky.
Also, I've seen a description of another Tesla coil based electron accelerator built in Russia called the RIUS-5 which could produce a 5 MV electron beam, and for which the secondary voltage ws said to reach 7 or 8 MV or something like that. But that machine is big and bulky.
this is rius-5
a 40ns low repetition rate multi kiloampere device - not what i want. on the other hand this is relus-5
rf driven linac with a very compact accelerating srtucture, like this one
coz u don't need an insulation for full output voltage/energy - that's what i want. and that's why i think all those "tesla" like devices are bs for home builders. and that multi beam device from your first post too - how is it different? it's for multi kw tasks basically, hence more than one beam, but i need 5 times more energy - not the average power. so microtrons/other cyclical systems are the way to go.
i've found even more interesting paper from the same author, at first glance atleast
never saw such a concept before. there is an english version
Re: particle accelerators
jpsmith123, Mon Aug 12 2019, 02:47AM
"coz u don't need an insulation for full output voltage/energy - that's what i want. and that's why i think all those "tesla" like devices are bs for home builders"
There's actually nothing "bullshit" about it.
"and that multi beam device from your first post too - how is it different? it's for multi kw tasks basically, hence more than one beam, but i need 5 times more energy"
Seriously? The reason I mentioned it is because of the principle involved, not because that particular design would meet your requirements. A field emission cathode situated opposite an anode foil is connected directly to a secondary coil, and the whole thing is under vacuum, thus avoiding a massive and generally problematic vacuum feedthrough insulator. It's relatively simple and cheap, and can theoretically be scaled up in voltage - without getting too much bigger physically - by running a single turn primary driven with fast HV pulses.
" - not the average power. so microtrons/other cyclical systems are the way to go."
Do you know what's involved with a microtron? I happen to have the book by Kapitza and Melekhin and I can tell you it would be involved. It's the way to go if you have many thousands of dollars to spend, a machine shop, all kinds of lab equipment, lots of free time, and you really know what you're doing. And considering the magnet and the power supply for the magnetron, it will not be very small.
Rather than do that - if you've got the resources - you'd probably be better off copying a design for a small PWT linac or a traveling wave linac from a published paper (e.g, thesis) somewhere.
jpsmith123, Mon Aug 12 2019, 02:47AM
"coz u don't need an insulation for full output voltage/energy - that's what i want. and that's why i think all those "tesla" like devices are bs for home builders"
There's actually nothing "bullshit" about it.
"and that multi beam device from your first post too - how is it different? it's for multi kw tasks basically, hence more than one beam, but i need 5 times more energy"
Seriously? The reason I mentioned it is because of the principle involved, not because that particular design would meet your requirements. A field emission cathode situated opposite an anode foil is connected directly to a secondary coil, and the whole thing is under vacuum, thus avoiding a massive and generally problematic vacuum feedthrough insulator. It's relatively simple and cheap, and can theoretically be scaled up in voltage - without getting too much bigger physically - by running a single turn primary driven with fast HV pulses.
" - not the average power. so microtrons/other cyclical systems are the way to go."
Do you know what's involved with a microtron? I happen to have the book by Kapitza and Melekhin and I can tell you it would be involved. It's the way to go if you have many thousands of dollars to spend, a machine shop, all kinds of lab equipment, lots of free time, and you really know what you're doing. And considering the magnet and the power supply for the magnetron, it will not be very small.
Rather than do that - if you've got the resources - you'd probably be better off copying a design for a small PWT linac or a traveling wave linac from a published paper (e.g, thesis) somewhere.
Re: particle accelerators
father dest, Mon Aug 12 2019, 07:08AM
"coz u don't need an insulation for full output voltage/energy - that's what i want. and that's why i think all those "tesla" like devices are bs for home builders"
>There's actually nothing "bullshit" about it.
i mean that it's not very practical to try to insulate voltages in the mv range at home.
>The reason I mentioned it is because of the principle involved
>avoiding a massive and generally problematic vacuum feedthrough insulator
i don't see any problems in getting huge voltages - tesla or not, there's many ways to accomplish that. and what insulator you talking about - why you need it? any example?
" - not the average power. so microtrons/other cyclical systems are the way to go."
>Do you know what's involved with a microtron? I happen to have the book by Kapitza and Melekhin
that book is WAY dated today - they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only.
and to tune pwt or any other rf linac you must know what you are doing anyway. and know very well.
father dest, Mon Aug 12 2019, 07:08AM
"coz u don't need an insulation for full output voltage/energy - that's what i want. and that's why i think all those "tesla" like devices are bs for home builders"
>There's actually nothing "bullshit" about it.
i mean that it's not very practical to try to insulate voltages in the mv range at home.
>The reason I mentioned it is because of the principle involved
>avoiding a massive and generally problematic vacuum feedthrough insulator
i don't see any problems in getting huge voltages - tesla or not, there's many ways to accomplish that. and what insulator you talking about - why you need it? any example?
" - not the average power. so microtrons/other cyclical systems are the way to go."
>Do you know what's involved with a microtron? I happen to have the book by Kapitza and Melekhin
that book is WAY dated today - they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only.
and to tune pwt or any other rf linac you must know what you are doing anyway. and know very well.
Re: particle accelerators
Sulaiman, Mon Aug 12 2019, 08:04AM
@father dest
the diagram that you showed above looks like a 'pulse forming network' (google it)
I helped to commision a 55 MeV linac, the pfn gave about 1 MV pulses to the anode of a klystron,
(actually four parallel units of 20 MW peak each), the rf was used to accelerate the electrons.
For hobby use a cyclotron may be easier to construct
Sulaiman, Mon Aug 12 2019, 08:04AM
@father dest
the diagram that you showed above looks like a 'pulse forming network' (google it)
I helped to commision a 55 MeV linac, the pfn gave about 1 MV pulses to the anode of a klystron,
(actually four parallel units of 20 MW peak each), the rf was used to accelerate the electrons.
For hobby use a cyclotron may be easier to construct
Re: particle accelerators
jpsmith123, Mon Aug 12 2019, 12:02PM
"i mean that it's not very practical to try to insulate voltages in the mv range at home"
Nor is it very "practical" to build an RF linear accelerator at home for that matter. That's apparently why you don't see people doing it on youtube. You have a choice between having to deal with HV insulation issues or having to deal with cost and complexity. Pick one.
"i don't see any problems in getting huge voltages - tesla or not, there's many ways to accomplish that. and what insulator you talking about - why you need it? any example?"
Okay, so you haven't done enough research. The problem isn't "getting huge voltages" per se, the problem is creating a semi-controllable "huge voltage" and using it to form a beam in a vacuum system in a system of practical size. Look around at some industrial multimegavolt systems. They're very large.
I suggested fast pulsed HV and vacuum insulation because this way there is no big insulator with problematic "triple points" no multipactor issue and the fast pulses greatly increase the breakdown voltages and keep the size down.
"that book is WAY dated today"
The principles haven't changed; you'll still need a big magnet.
"and to tune pwt or any other rf linac you must know what you are doing anyway. and know very well."
Well of course you must. Why are you asking here if you're an expert?
"- they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
References in support, please.
jpsmith123, Mon Aug 12 2019, 12:02PM
"i mean that it's not very practical to try to insulate voltages in the mv range at home"
Nor is it very "practical" to build an RF linear accelerator at home for that matter. That's apparently why you don't see people doing it on youtube. You have a choice between having to deal with HV insulation issues or having to deal with cost and complexity. Pick one.
"i don't see any problems in getting huge voltages - tesla or not, there's many ways to accomplish that. and what insulator you talking about - why you need it? any example?"
Okay, so you haven't done enough research. The problem isn't "getting huge voltages" per se, the problem is creating a semi-controllable "huge voltage" and using it to form a beam in a vacuum system in a system of practical size. Look around at some industrial multimegavolt systems. They're very large.
I suggested fast pulsed HV and vacuum insulation because this way there is no big insulator with problematic "triple points" no multipactor issue and the fast pulses greatly increase the breakdown voltages and keep the size down.
"that book is WAY dated today"
The principles haven't changed; you'll still need a big magnet.
"and to tune pwt or any other rf linac you must know what you are doing anyway. and know very well."
Well of course you must. Why are you asking here if you're an expert?
"- they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
References in support, please.
Re: particle accelerators
father dest, Mon Aug 12 2019, 01:00PM
"i mean that it's not very practical to try to insulate voltages in the mv range at home"
>Nor is it very "practical" to build an RF linear accelerator at home for that matter. That's apparently why you don't see people doing it on youtube. You have a choice between having to deal with HV insulation issues or having to deal with cost and complexity. Pick one.
so my pick is number three then - a microtron, or some other type of cyclic accelerator.
"that book is WAY dated today"
>The principles haven't changed
yea, but there is a ton of new ones, which were unheard of at the time of that book.
>you'll still need a big magnet.
i don't - if i am using those new principles. so as u've said above - "you haven't done enough research". read the last paper of G.V. Dolbilov from my posts for example:
"- they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
>References in support, please.
father dest, Mon Aug 12 2019, 01:00PM
"i mean that it's not very practical to try to insulate voltages in the mv range at home"
>Nor is it very "practical" to build an RF linear accelerator at home for that matter. That's apparently why you don't see people doing it on youtube. You have a choice between having to deal with HV insulation issues or having to deal with cost and complexity. Pick one.
so my pick is number three then - a microtron, or some other type of cyclic accelerator.
"that book is WAY dated today"
>The principles haven't changed
yea, but there is a ton of new ones, which were unheard of at the time of that book.
>you'll still need a big magnet.
i don't - if i am using those new principles. so as u've said above - "you haven't done enough research". read the last paper of G.V. Dolbilov from my posts for example:
wrote ...
...key parameters of the electron accelerator on energy E = 10MeV
The maximal size of a magnetic induction of С-shaped cores is equal B0max = mγv / eR0 = 0.067 T
...magnetic induction О-shaped cores does not exceed B = 0.1T
To realize such accelerating system the minimum of 10 ferromagnetic cores with the sizes 125 x 80 x 10 mm is required.
...key parameters of the electron accelerator on energy E = 10MeV
The maximal size of a magnetic induction of С-shaped cores is equal B0max = mγv / eR0 = 0.067 T
...magnetic induction О-shaped cores does not exceed B = 0.1T
To realize such accelerating system the minimum of 10 ferromagnetic cores with the sizes 125 x 80 x 10 mm is required.
"- they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
>References in support, please.
Re: particle accelerators
jpsmith123, Mon Aug 12 2019, 10:48PM
"so my pick is number three then - a microtron, or some other type of cyclic accelerator."
I hate to be the bearer of bad news but ANY circular accelerator comes under the "cost and complexity" category; that is to say, any circular accelerator is generally going to be way beyond the resources and capability of a typical hobbyist.
"yea, but there is a ton of new ones, which were unheard of at the time of that book."
Please provide a link proving the existence of a working microtron that is technologically so far advanced in some meaningful sense, compared with the microtrons described in the book by Kapitza, as to be reasonably described as "unheard of."
" they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
Who does? This sounds like somebody's research proposal, not a description of a working microtron. To the extent it's possible in the first place that's not something you're going to build.
jpsmith123, Mon Aug 12 2019, 10:48PM
"so my pick is number three then - a microtron, or some other type of cyclic accelerator."
I hate to be the bearer of bad news but ANY circular accelerator comes under the "cost and complexity" category; that is to say, any circular accelerator is generally going to be way beyond the resources and capability of a typical hobbyist.
"yea, but there is a ton of new ones, which were unheard of at the time of that book."
Please provide a link proving the existence of a working microtron that is technologically so far advanced in some meaningful sense, compared with the microtrons described in the book by Kapitza, as to be reasonably described as "unheard of."
" they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
Who does? This sounds like somebody's research proposal, not a description of a working microtron. To the extent it's possible in the first place that's not something you're going to build.
Re: particle accelerators
2Spoons, Tue Aug 13 2019, 12:17AM
I had a bit of a look into plasma wake accelerators - but I believe they require a very fast laser pulse. Might still be doable for someone really keen.
2Spoons, Tue Aug 13 2019, 12:17AM
I had a bit of a look into plasma wake accelerators - but I believe they require a very fast laser pulse. Might still be doable for someone really keen.
Re: particle accelerators
father dest, Tue Aug 13 2019, 06:05PM
>I hate to be the bearer of bad news but ANY circular accelerator comes under the "cost and complexity" category; that is to say, any circular accelerator is generally going to be way beyond the resources and capability of a typical hobbyist.
this dude almost did it -
it is sad he abandoned the project.
and you're insisting that this is maximum what we can get at home:
right?
"yea, but there is a ton of new ones, which were unheard of at the time of that book."
>Please provide a link proving the existence of a working microtron that is technologically so far advanced in some meaningful sense, compared with the microtrons described in the book by Kapitza, as to be reasonably described as "unheard of."
i was talking about principles, not about devices - are you saying that any and every new principle means instant huge technological leap forward? that's not the case of course. been busy studying Dolbilin's patents, so can't tell right now, but if i remember correctly they work on other modes of acceleration nowadays, the modes that guys from old era wasn't considering optimal/workable, or something like that.
btw - all 3 Dolbilin's patents are total bs - they work on paper, but require insane materials/semiconductors in reality.
" they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
>Who does? This sounds like somebody's research proposal, not a description of a working microtron. To the extent it's possible in the first place that's not something you're going to build.
these dudes -
it's the device from that "research proposal", the magnet weight is only 40kg - electromagnet, can be reduced to 20 kilos by swapping copper on neodymium.
father dest, Tue Aug 13 2019, 06:05PM
>I hate to be the bearer of bad news but ANY circular accelerator comes under the "cost and complexity" category; that is to say, any circular accelerator is generally going to be way beyond the resources and capability of a typical hobbyist.
this dude almost did it -
it is sad he abandoned the project.
and you're insisting that this is maximum what we can get at home:
right?
"yea, but there is a ton of new ones, which were unheard of at the time of that book."
>Please provide a link proving the existence of a working microtron that is technologically so far advanced in some meaningful sense, compared with the microtrons described in the book by Kapitza, as to be reasonably described as "unheard of."
i was talking about principles, not about devices - are you saying that any and every new principle means instant huge technological leap forward? that's not the case of course. been busy studying Dolbilin's patents, so can't tell right now, but if i remember correctly they work on other modes of acceleration nowadays, the modes that guys from old era wasn't considering optimal/workable, or something like that.
btw - all 3 Dolbilin's patents are total bs - they work on paper, but require insane materials/semiconductors in reality.
" they build microtrons on neodymium magnets these days, with iron core weight about 20 kilos only."
>Who does? This sounds like somebody's research proposal, not a description of a working microtron. To the extent it's possible in the first place that's not something you're going to build.
these dudes -
it's the device from that "research proposal", the magnet weight is only 40kg - electromagnet, can be reduced to 20 kilos by swapping copper on neodymium.
Re: particle accelerators
jpsmith123, Wed Aug 14 2019, 01:55AM
If he "almost" did it he probably wouldn't have abandoned the project after all the time and money spent. Apparently he abandoned it because it was a total failure. Most likely he didn't do enough research beforehand to appreciate what he was getting into.
No not at all. The device in that picture apparently has nothing to do with the approach I suggested. (And there are other possibilities that I didn't even mention).
Principles don't make electron beams and/or x-rays; you need hardware for that.
Huh? That's what you seem to be saying. You seem to be implying that the existence of a research proposal that suggests the possibility of an x band microtron with a relatively small magnet makes Kapitza's book obsolete. It doesn't. Moreover, even if someone was able to make a practical portable x band microtron with a relatively small magnet, all the other design and construction issues are still there so the book is not outdated/obsolete by any means.
Show me a working example of the hardware that makes everything in Kapitza's book outdated/obsolete.
BTW books could be written about various accelerator concepts that seemed plausible, were tried, but never worked out in practice; e.g. the "megatron" (plasma betatron); the "nested high voltage accelerator"; the "electron auto-accelerator"; the "high current betatron"; are a few that come to mind.
No; you're looking at it all wrong. A patent is nothing more than a legal record of somebody's idea; it's not a "how to" article. It doesn't have to show merit and it often doesn't have to be very detailed.
I don't know how it works in Russia but in the U.S. there's something called the "Small Business Innovation Research" program whereby people submit
various proposals to the government and many times they get funding to do the research. I've followed some of these projects and I think some of these people are in a sense "scammers." They proffer some facially plausible but very high risk ideas that get funded with a grant but nothing ever comes of it. I think they use it as a way to fund a start-up company.
An example is a high current betatron proposed by the Adelphi company. IIRC they proposed to design and build a high current betatron using ferrite instead of silicon steel. The simple and straightforward idea was that if the operating frequency was scaled up - everything else being the same - they could get a much higher average current. (I was so interested in this project that I corresponded with the principal investigator on the project asking things like what kind of ferrite was being used, etc.) They got funding for it but for some reason the high current betatron was never created, AFAIK.
I can imagine the same kind of thing happening with the proposal for the x-band portable microtron: It seems plausible at first but they start building it and then discover that they can't get the magnetic field uniformity they need so they start adding shims and/or coils and then another power supply. And then it turns out to be too temperature sensitive so now they have to add a cooling system and pretty soon it looks nothing like what they originally imagined and it never happens.
jpsmith123, Wed Aug 14 2019, 01:55AM
"this dude almost did it - it is sad he abandoned the project."
If he "almost" did it he probably wouldn't have abandoned the project after all the time and money spent. Apparently he abandoned it because it was a total failure. Most likely he didn't do enough research beforehand to appreciate what he was getting into.
"and you're insisting that this is maximum what we can get at home:right?"
No not at all. The device in that picture apparently has nothing to do with the approach I suggested. (And there are other possibilities that I didn't even mention).
"i was talking about principles, not about devices"
Principles don't make electron beams and/or x-rays; you need hardware for that.
"are you saying that any and every new principle means instant huge technological leap forward? that's not the case of course."
Huh? That's what you seem to be saying. You seem to be implying that the existence of a research proposal that suggests the possibility of an x band microtron with a relatively small magnet makes Kapitza's book obsolete. It doesn't. Moreover, even if someone was able to make a practical portable x band microtron with a relatively small magnet, all the other design and construction issues are still there so the book is not outdated/obsolete by any means.
"been busy studying Dolbilin's patents, so can't tell right now, but if i remember correctly they work on other modes of acceleration nowadays, the modes that guys from old era wasn't considering optimal/workable, or something like that.btw"
Show me a working example of the hardware that makes everything in Kapitza's book outdated/obsolete.
BTW books could be written about various accelerator concepts that seemed plausible, were tried, but never worked out in practice; e.g. the "megatron" (plasma betatron); the "nested high voltage accelerator"; the "electron auto-accelerator"; the "high current betatron"; are a few that come to mind.
"- all 3 Dolbilin's patents are total bs - they work on paper, but require insane materials/semiconductors in reality."
No; you're looking at it all wrong. A patent is nothing more than a legal record of somebody's idea; it's not a "how to" article. It doesn't have to show merit and it often doesn't have to be very detailed.
"these dudes - it's the device from that "research proposal", the magnet weight is only 40kg - electromagnet, can be reduced to 20 kilos by swapping copper on neodymium."
I don't know how it works in Russia but in the U.S. there's something called the "Small Business Innovation Research" program whereby people submit
various proposals to the government and many times they get funding to do the research. I've followed some of these projects and I think some of these people are in a sense "scammers." They proffer some facially plausible but very high risk ideas that get funded with a grant but nothing ever comes of it. I think they use it as a way to fund a start-up company.
An example is a high current betatron proposed by the Adelphi company. IIRC they proposed to design and build a high current betatron using ferrite instead of silicon steel. The simple and straightforward idea was that if the operating frequency was scaled up - everything else being the same - they could get a much higher average current. (I was so interested in this project that I corresponded with the principal investigator on the project asking things like what kind of ferrite was being used, etc.) They got funding for it but for some reason the high current betatron was never created, AFAIK.
I can imagine the same kind of thing happening with the proposal for the x-band portable microtron: It seems plausible at first but they start building it and then discover that they can't get the magnetic field uniformity they need so they start adding shims and/or coils and then another power supply. And then it turns out to be too temperature sensitive so now they have to add a cooling system and pretty soon it looks nothing like what they originally imagined and it never happens.
Re: particle accelerators
father dest, Wed Aug 14 2019, 07:38AM
>If he "almost" did it he probably wouldn't have abandoned the project after all the time and money spent. Apparently he abandoned it because it was a total failure. Most likely he didn't do enough research beforehand to appreciate what he was getting into.
i can't understand - are u being so damn sceptical about almost anything, or are u so damn good at accelerators theory that u know everything in advance? lol, jk.
>The device in that picture apparently has nothing to do with the approach I suggested. (And there are other possibilities that I didn't even mention).
can u speak some more about those "other" variants too? coz i don't like the author of that helical thing already - i see him like some sort of a troll.
btw - he wrote in his next patent than helical thing had some drawbacks so he replaced it with that "tesla-like" thing i posted above.
"are you saying that any and every new principle means instant huge technological leap forward? that's not the case of course."
>Huh? That's what you seem to be saying. You seem to be implying that the existence of a research proposal that suggests the possibility of an x band microtron with a relatively small magnet makes Kapitza's book obsolete. It doesn't.
idk - maybe it's translation problems (english is no my 1st or even 2st language), or maybe it is my fault in the way of formulating thougts - just forget about it.
let's just accelerate! forward : D
father dest, Wed Aug 14 2019, 07:38AM
>If he "almost" did it he probably wouldn't have abandoned the project after all the time and money spent. Apparently he abandoned it because it was a total failure. Most likely he didn't do enough research beforehand to appreciate what he was getting into.
i can't understand - are u being so damn sceptical about almost anything, or are u so damn good at accelerators theory that u know everything in advance? lol, jk.
>The device in that picture apparently has nothing to do with the approach I suggested. (And there are other possibilities that I didn't even mention).
can u speak some more about those "other" variants too? coz i don't like the author of that helical thing already - i see him like some sort of a troll.
btw - he wrote in his next patent than helical thing had some drawbacks so he replaced it with that "tesla-like" thing i posted above.
"are you saying that any and every new principle means instant huge technological leap forward? that's not the case of course."
>Huh? That's what you seem to be saying. You seem to be implying that the existence of a research proposal that suggests the possibility of an x band microtron with a relatively small magnet makes Kapitza's book obsolete. It doesn't.
idk - maybe it's translation problems (english is no my 1st or even 2st language), or maybe it is my fault in the way of formulating thougts - just forget about it.
let's just accelerate! forward : D
Re: particle accelerators
father dest, Wed Aug 14 2019, 06:40PM
i think this guy is a troll look at it:
17 cm dia ferrite cores inside the secondary - lol? : )
the inverter drives resonance transformer. at it's resonance frequency. but you can't just drive tesla with square wave at Fres - your primary current would rise infinitely as far as i remember. in the case of no load atleast.
and no real pictorials as always, even at conference:
the guys you thinkin were trying to get money for microtron startup company had posted real photos of their working prototype at conference, unlike this jockey : D
father dest, Wed Aug 14 2019, 06:40PM
jpsmith123 wrote ...
I came to the conclusion that a voltage-scaled-up version of the "multibeam accelerator" described by G.V. Dolbilov et al. might be one approach (there are a few other possibilities, IMO).
This design eliminates the problem of a big and bulky vacuum feedthrough insulator and associated problems.
I came to the conclusion that a voltage-scaled-up version of the "multibeam accelerator" described by G.V. Dolbilov et al. might be one approach (there are a few other possibilities, IMO).
This design eliminates the problem of a big and bulky vacuum feedthrough insulator and associated problems.
i think this guy is a troll
look at it:17 cm dia ferrite cores inside the secondary - lol? : )
This device apparently uses a multi-turn primary driven with 500 volt pulses at 18 khz or something like that. But to scale up the voltage without making it too big, I think you'd need to drive the primary at a much higher voltage with a very short pulse (sub-microsecond), and use a lower turns ratio.
the inverter drives resonance transformer. at it's resonance frequency. but you can't just drive tesla with square wave at Fres - your primary current would rise infinitely as far as i remember. in the case of no load atleast.
and no real pictorials as always, even at conference:
the guys you thinkin were trying to get money for microtron startup company had posted real photos of their working prototype at conference, unlike this jockey : D
Re: particle accelerators
jpsmith123, Thu Aug 15 2019, 04:37PM
Unfortunately the several published papers on the "multibeam accelerator" are seriously lacking in detail, but I don't think it's fair to call the inventor a "troll."
Anyway, I also had questions about how the primary was being driven. One of the papers mentioned something about an "inverter" made by a company in Bulgaria.
I tried to research that but I couldn't find anything. But I did find the following linked paper which apparently shows a 300 kv unit installed in Japan. It also shows a block diagram of the "inverter" comprised of a DC power supply and a "modulator" (See figures 1,2 and 3).
So from this I assume the accelerator exists and must be fairly rugged and reliable.
BTW here's another interesting accelerator idea that seemed promising, but then I never heard anything more about it ever again:
jpsmith123, Thu Aug 15 2019, 04:37PM
Unfortunately the several published papers on the "multibeam accelerator" are seriously lacking in detail, but I don't think it's fair to call the inventor a "troll."
Anyway, I also had questions about how the primary was being driven. One of the papers mentioned something about an "inverter" made by a company in Bulgaria.
I tried to research that but I couldn't find anything. But I did find the following linked paper which apparently shows a 300 kv unit installed in Japan. It also shows a block diagram of the "inverter" comprised of a DC power supply and a "modulator" (See figures 1,2 and 3).
So from this I assume the accelerator exists and must be fairly rugged and reliable.
BTW here's another interesting accelerator idea that seemed promising, but then I never heard anything more about it ever again:
Re: particle accelerators
father dest, Fri Aug 16 2019, 09:33AM
hurmmm - how bout dat?
it's from 2010 -
father dest, Fri Aug 16 2019, 09:33AM
jpsmith123 wrote ...
BTW here's another interesting accelerator idea that seemed promising, but then I never heard anything more about it ever again:
BTW here's another interesting accelerator idea that seemed promising, but then I never heard anything more about it ever again:
hurmmm - how bout dat?
it's from 2010 -
Re: particle accelerators
Conundrum, Sat Aug 17 2019, 06:30AM
No, Nd magnets are not used because the Curie point is far too low.
Incidentally some hobbyists are trying ReBCO based superconducting magnets as LN2 is easy to get hold of.
Obviously the problem is getting a good enough physical structure and for high field magnets cooling is less of a problem than making something that can withstand the huge forces trying to blow it apart.
I did look into making a basic HTSC magnet, as building a concentric design is barely doable.
This would be analogous to a Tesla Coil primary and as such not capable of much field except in the bore, and I'd need to use a conventional magnet to boost it. Incidentally Nd magnets are well known to get stronger with low temperature!
Maybe combine the two and use an optimized NdFeB magnet to get maximum possible field at say 200K which is doable using solvent + dry ice.
Conundrum, Sat Aug 17 2019, 06:30AM
No, Nd magnets are not used because the Curie point is far too low.
Incidentally some hobbyists are trying ReBCO based superconducting magnets as LN2 is easy to get hold of.
Obviously the problem is getting a good enough physical structure and for high field magnets cooling is less of a problem than making something that can withstand the huge forces trying to blow it apart.
I did look into making a basic HTSC magnet, as building a concentric design is barely doable.
This would be analogous to a Tesla Coil primary and as such not capable of much field except in the bore, and I'd need to use a conventional magnet to boost it. Incidentally Nd magnets are well known to get stronger with low temperature!
Maybe combine the two and use an optimized NdFeB magnet to get maximum possible field at say 200K which is doable using solvent + dry ice.
Re: particle accelerators
jpsmith123, Sat Aug 17 2019, 02:36PM
Thanks for the link.
It seems they've changed the design a little bit from that described in the earlier paper.
I'm disappointed that the average current from that device is apparently only a few microamps (although that's more than you'd get with a conventional betatron of a similar size).
Apparently I was overestimating the average current you could get from a frequency scaled betatron. For one thing, it seems that as the frequency increases you'd have less time to inject charge. And the amount of injected charge that would actually be trapped would depend on the type of focusing, the accelerating gradient (volts/turn) and the injection energy, so there are a few variables involved.
jpsmith123, Sat Aug 17 2019, 02:36PM
Thanks for the link.
It seems they've changed the design a little bit from that described in the earlier paper.
I'm disappointed that the average current from that device is apparently only a few microamps (although that's more than you'd get with a conventional betatron of a similar size).
Apparently I was overestimating the average current you could get from a frequency scaled betatron. For one thing, it seems that as the frequency increases you'd have less time to inject charge. And the amount of injected charge that would actually be trapped would depend on the type of focusing, the accelerating gradient (volts/turn) and the injection energy, so there are a few variables involved.
hurmmm - how bout dat?
it's from 2010
Re: particle accelerators
Sulaiman, Sat Aug 17 2019, 02:48PM
A few microamperes ...
1.6 uA / 1.6x10^-19 C = 10^13 Bq !!!
(current / charge of an electron = electrons per second)
P.S. 1 MeV electrons can penetrate about 2mm aluminium.
Sulaiman, Sat Aug 17 2019, 02:48PM
A few microamperes ...
1.6 uA / 1.6x10^-19 C = 10^13 Bq !!!
(current / charge of an electron = electrons per second)
P.S. 1 MeV electrons can penetrate about 2mm aluminium.
Re: particle accelerators
father dest, Sat Aug 17 2019, 08:02PM
where you got that number - are you reading kanji? : )
there is written here - "30 kV，パルス幅 2μs，繰り返㗠1 kHz ã®ãƒ‘ルス高電 圧を発生ã•ã›ã‚‹ IGBT", so apparently 5a peak current for 2us pulse at 1khz - that would be 2.5ma average - too good to be true.
but in first paper they show oscillograms, from which you can tell, that acceleration time is 200us, and in second paper from the graph of core field you can clearly see, that extraction time = acc time, so 200us too. tho that would mean 250ma average current which is insane : D
need english version of that 2010 paper. seems like this type of acceleration (ffag) is very popular in nippon, for a big machines atleast, and they describe rf acceleration instead induction too - wanna read bout that more.
father dest, Sat Aug 17 2019, 08:02PM
jpsmith123 wrote ...
I'm disappointed that the average current from that device is apparently only a few microamps
I'm disappointed that the average current from that device is apparently only a few microamps
where you got that number - are you reading kanji? : )
there is written here - "30 kV，パルス幅 2μs，繰り返㗠1 kHz ã®ãƒ‘ルス高電 圧を発生ã•ã›ã‚‹ IGBT", so apparently 5a peak current for 2us pulse at 1khz - that would be 2.5ma average - too good to be true.
but in first paper they show oscillograms, from which you can tell, that acceleration time is 200us, and in second paper from the graph of core field you can clearly see, that extraction time = acc time, so 200us too. tho that would mean 250ma average current which is insane : D
For one thing, it seems that as the frequency increases you'd have less time to inject charge. And the amount of injected charge that would actually be trapped would depend on the type of focusing, the accelerating gradient (volts/turn) and the injection energy, so there are a few variables involved.
need english version of that 2010 paper. seems like this type of acceleration (ffag) is very popular in nippon, for a big machines atleast, and they describe rf acceleration instead induction too - wanna read bout that more.
Re: particle accelerators
father dest, Sat Aug 17 2019, 08:02PM
becquerel? an unit of radioactivity? : )
father dest, Sat Aug 17 2019, 08:02PM
Sulaiman wrote ...
1.6 uA / 1.6x10^-19 C = 10^13 Bq !!!
(current / charge of an electron = electrons per second)
1.6 uA / 1.6x10^-19 C = 10^13 Bq !!!
(current / charge of an electron = electrons per second)
becquerel? an unit of radioactivity? : )
Re: particle accelerators
father dest, Sat Aug 17 2019, 08:17PM
btw, guys - i wanna build me such a machine not just for fun and giggles - i wanna see cherenkoff radiation from it, in water. so the question is - are human eyes capable of seeing microsecond pulses with high repetition rate (more than 50hz) or not? coz if the latter is true - i am doomed.
father dest, Sat Aug 17 2019, 08:17PM
btw, guys - i wanna build me such a machine not just for fun and giggles - i wanna see cherenkoff radiation from it, in water. so the question is - are human eyes capable of seeing microsecond pulses with high repetition rate (more than 50hz) or not? coz if the latter is true - i am doomed.
Re: particle accelerators
father dest, Sat Aug 17 2019, 09:26PM
no, it's written there - "Electron gun high voltage power supply is voltage 30 kV, pulse width 2 μs, repetitive pulse 1 kHz"
"The size of the power supply includes the electromagnetic power supply for incident and emission, 35×60×45 cm and weighs less than 40 kg"
"electrons flying 20000 laps", so about 50kev gain for one turn
"The vacuum chamber is made of machinable ceramic. if the electron beam collides with the inner surface of the chamber, to prevent the electric charge accumulation Conductive coating (ITO film) used. The thickness of the vacuum chamber is 1 mm at the thinnest position.
external turbo molecular pump was uses int the prototype"
"A vibration damper ( black part in Fig. 5) was attached. Without a damper, when exciting the bending magnet at 1 kHz vibrations that occur are transmitted to the X-ray target"
Figure 12 shows an oscilloscope with four acceleration cycles (4 ms)
The magnetic field strength of the deflection electromagnet is about 0.2T, and the acceleration The magnetic field strength is about 0.6T.
pulses of 100A-200V for the main coil of the bending magnet at 1kHz. for cw a 20kW large electromagnet power supply is required, resulting in high costs.
Almost no power is lost in the deflection magnet coil, place a capacitor in parallel with the coil. LC resonance circuit and deflecting electromagnet
Resonance type power supply
electromagnetic power supply of less than 1kW
father dest, Sat Aug 17 2019, 09:26PM
father dest wrote ...
apparently 5a peak current for 2us pulse at 1khz
apparently 5a peak current for 2us pulse at 1khz
no, it's written there - "Electron gun high voltage power supply is voltage 30 kV, pulse width 2 μs, repetitive pulse 1 kHz"
"The size of the power supply includes the electromagnetic power supply for incident and emission, 35×60×45 cm and weighs less than 40 kg"
"electrons flying 20000 laps", so about 50kev gain for one turn
"The vacuum chamber is made of machinable ceramic. if the electron beam collides with the inner surface of the chamber, to prevent the electric charge accumulation Conductive coating (ITO film) used. The thickness of the vacuum chamber is 1 mm at the thinnest position.
external turbo molecular pump was uses int the prototype"
"A vibration damper ( black part in Fig. 5) was attached. Without a damper, when exciting the bending magnet at 1 kHz vibrations that occur are transmitted to the X-ray target"
Figure 12 shows an oscilloscope with four acceleration cycles (4 ms)
The magnetic field strength of the deflection electromagnet is about 0.2T, and the acceleration The magnetic field strength is about 0.6T.
pulses of 100A-200V for the main coil of the bending magnet at 1kHz. for cw a 20kW large electromagnet power supply is required, resulting in high costs.
Almost no power is lost in the deflection magnet coil, place a capacitor in parallel with the coil. LC resonance circuit and deflecting electromagnet
Resonance type power supply
electromagnetic power supply of less than 1kW
Re: particle accelerators
father dest, Sat Aug 17 2019, 11:23PM
damn - it's written in the first english document - "Average beam current is estimated about 5 micro A".
but - there is another japanese paper -
they build 300mm in dia device, 6MeV and 430 R/min at the distance of 1m - that's some serious power already. injection time - 20us.
Fixed field betatrons have potentially a much higher intensity than conventional betatrons. Beam can be injected for a considerable fraction of a cycle, if extra accelerating flux is available, rather than the few tenths of a microsecond presently possible. The only beam current limitation appears to be space charge at injection, and this may be decreased by such techniques as high voltage injection. An FFAG betatron has no problems of tracking a pulsed guide field with the accelerating flux, and has also other engineering simplification
father dest, Sat Aug 17 2019, 11:23PM
father dest wrote ...
where you got that number - are you reading kanji? : )
jpsmith123 wrote ...
I'm disappointed that the average current from that device is apparently only a few microamps
I'm disappointed that the average current from that device is apparently only a few microamps
where you got that number - are you reading kanji? : )
damn - it's written in the first english document - "Average beam current is estimated about 5 micro A".
but - there is another japanese paper -
they build 300mm in dia device, 6MeV and 430 R/min at the distance of 1m - that's some serious power already. injection time - 20us.
Fixed field betatrons have potentially a much higher intensity than conventional betatrons. Beam can be injected for a considerable fraction of a cycle, if extra accelerating flux is available, rather than the few tenths of a microsecond presently possible. The only beam current limitation appears to be space charge at injection, and this may be decreased by such techniques as high voltage injection. An FFAG betatron has no problems of tracking a pulsed guide field with the accelerating flux, and has also other engineering simplification
Re: particle accelerators
Sulaiman, Sun Aug 18 2019, 12:51AM
I do not have an 'equivalent to' symbol on my keyboard,
if you prefer ... 10^13 counts per second.
.... 600000000000000 counts per minute.
Sulaiman, Sun Aug 18 2019, 12:51AM
father dest wrote ...
becquerel? an unit of radioactivity? : )
Sulaiman wrote ...
1.6 uA / 1.6x10^-19 C = 10^13 Bq !!!
(current / charge of an electron = electrons per second)
1.6 uA / 1.6x10^-19 C = 10^13 Bq !!!
(current / charge of an electron = electrons per second)
becquerel? an unit of radioactivity? : )
I do not have an 'equivalent to' symbol on my keyboard,
if you prefer ... 10^13 counts per second.
.... 600000000000000 counts per minute.
Re: particle accelerators
father dest, Sun Aug 18 2019, 07:34AM
it's like ~2 gramms of strontium-90 : )
father dest, Sun Aug 18 2019, 07:34AM
it's like ~2 gramms of strontium-90 : )
Re: particle accelerators
jpsmith123, Tue Aug 20 2019, 04:27PM
Wow that's somewhat more radiation than I would expect.
On page 176 of the book by Kapitza and Melekhin is given an empirical equation for calculating the "bremsstrahlung intensity" (apparently from an optimally thick tungsten target):
r (roentgens/minute @ 1.0 meter from the target) = 0.04 * W^3 * I (where W is the electron energy in MeV and I is the electron current in uA).
So if r = 430 and W = 6, solving this equation suggests average current I = 49.77 uA (unless I made a mistake which is very possible).
Does the paper give any numbers for the circulating current and the radius of the beam's orbit at the target? If so it seems we should be able to calculate the trapped charge, q, and then multiply by the frequency, f, to determine the average current I.
I could be wrong, but I see it like this:
q = coulombs/second * seconds (where coulombs/second = circulating current; and seconds = circumference of electron beam orbit/electron velocity)
I don't know what these numbers actually are in this case but just to get a ball park idea let's say that circulating current is 8 amps; the beam radius where it strikes the target is 12.5 cm; the velocity of the electrons is roughly 3 x 10^10 cm/sec; and the frequency is 1 kHz.
Then I = (8 coulombs/sec) * (2 * pi * 12.5 cm)/(3 * 10^10 cm/sec) * 1000/sec = 21 uA
I don't know why these two numbers differ so much. Perhaps the bremsstrahlung formula in the book is wrong, or needs some additional qualification or something, or maybe my thinking is wrong somewhere.
Anyway, if I could find a cheap 5 MW pulse magnetron somewhere or a section of an S-band accelerator tube on ebay I might be tempted to try to build a small RF linear accelerator; otherwise the cost and complexity would be a show stopper for me.
So my presently held belief is that the only practical approach to a low end (a few MeV) accelerator (for someone with my limited resources) is the use of fast DC HV pulses. As I see it, this could possibly be in the form of a modified "Multibeam accelerator"; or in the form of pulse driven resonant cavities; or in the form of a Marx generator driving a coaxial transformer (where the Marx generator current pulse is in the Z direction and the magnetic field is in the theta direction in cyl. coordinates); or where a fast Marx generator drives a (possibly magnetically insulated) tapered line transformer, etc.
jpsmith123, Tue Aug 20 2019, 04:27PM
"they build 300mm in dia device, 6MeV and 430 R/min at the distance of 1m - that's some serious power already. injection time - 20us."
Wow that's somewhat more radiation than I would expect.
On page 176 of the book by Kapitza and Melekhin is given an empirical equation for calculating the "bremsstrahlung intensity" (apparently from an optimally thick tungsten target):
r (roentgens/minute @ 1.0 meter from the target) = 0.04 * W^3 * I (where W is the electron energy in MeV and I is the electron current in uA).
So if r = 430 and W = 6, solving this equation suggests average current I = 49.77 uA (unless I made a mistake which is very possible).
Does the paper give any numbers for the circulating current and the radius of the beam's orbit at the target? If so it seems we should be able to calculate the trapped charge, q, and then multiply by the frequency, f, to determine the average current I.
I could be wrong, but I see it like this:
q = coulombs/second * seconds (where coulombs/second = circulating current; and seconds = circumference of electron beam orbit/electron velocity)
I don't know what these numbers actually are in this case but just to get a ball park idea let's say that circulating current is 8 amps; the beam radius where it strikes the target is 12.5 cm; the velocity of the electrons is roughly 3 x 10^10 cm/sec; and the frequency is 1 kHz.
Then I = (8 coulombs/sec) * (2 * pi * 12.5 cm)/(3 * 10^10 cm/sec) * 1000/sec = 21 uA
I don't know why these two numbers differ so much. Perhaps the bremsstrahlung formula in the book is wrong, or needs some additional qualification or something, or maybe my thinking is wrong somewhere.
Anyway, if I could find a cheap 5 MW pulse magnetron somewhere or a section of an S-band accelerator tube on ebay I might be tempted to try to build a small RF linear accelerator; otherwise the cost and complexity would be a show stopper for me.
So my presently held belief is that the only practical approach to a low end (a few MeV) accelerator (for someone with my limited resources) is the use of fast DC HV pulses. As I see it, this could possibly be in the form of a modified "Multibeam accelerator"; or in the form of pulse driven resonant cavities; or in the form of a Marx generator driving a coaxial transformer (where the Marx generator current pulse is in the Z direction and the magnetic field is in the theta direction in cyl. coordinates); or where a fast Marx generator drives a (possibly magnetically insulated) tapered line transformer, etc.
Re: particle accelerators
father dest, Wed Aug 21 2019, 06:35PM
yes - 8a and 0.125m, and i don't see any errors in your calculations.
can you help me with evaluating some basic parameters of that 6 mev machine, like expected coils currents and so on?
why they're feeding electromagnet with sinusoidal current in the prototype, when according to their graph "bending field", there has to be times with constant field?
father dest, Wed Aug 21 2019, 06:35PM
jpsmith123 wrote ...
Does the paper give any numbers for the circulating current and the radius of the beam's orbit at the target?
Does the paper give any numbers for the circulating current and the radius of the beam's orbit at the target?
yes - 8a and 0.125m, and i don't see any errors in your calculations.
can you help me with evaluating some basic parameters of that 6 mev machine, like expected coils currents and so on?
why they're feeding electromagnet with sinusoidal current in the prototype, when according to their graph "bending field", there has to be times with constant field?
Re: particle accelerators
Conundrum, Thu Aug 22 2019, 11:23AM
Useful, thanks.
Incidentally a "Poor mans particle accelerator" can be made using He gas as the mean free path is quite long compared with air and a combination of He-Ar can get reasonable results. See plasma globes!
You can certainly get multipaction with He but it would be more of a glow discharge than true collisions. See Sam's FAQ.
Conundrum, Thu Aug 22 2019, 11:23AM
Useful, thanks.
Incidentally a "Poor mans particle accelerator" can be made using He gas as the mean free path is quite long compared with air and a combination of He-Ar can get reasonable results. See plasma globes!
You can certainly get multipaction with He but it would be more of a glow discharge than true collisions. See Sam's FAQ.
Re: particle accelerators
jpsmith123, Sun Aug 25 2019, 05:26AM
@ Father Dest
I don't know very much about FFAG focusing. I never seriously looked into it, partly because I thought that the fabrication of magnetic pole pieces would be a show-stopper, considering my limited resources.
As I see it, it would probably be easier for me to make a small RF linear accelerator than any type of circular accelerator.
Anyway, I'll post one or two more ideas about this subject one of these days soon.
@ Conundrum
I'm not sure exactly what you're getting at regarding the use of helium.
jpsmith123, Sun Aug 25 2019, 05:26AM
@ Father Dest
I don't know very much about FFAG focusing. I never seriously looked into it, partly because I thought that the fabrication of magnetic pole pieces would be a show-stopper, considering my limited resources.
As I see it, it would probably be easier for me to make a small RF linear accelerator than any type of circular accelerator.
Anyway, I'll post one or two more ideas about this subject one of these days soon.
@ Conundrum
I'm not sure exactly what you're getting at regarding the use of helium.
Re: particle accelerators
father dest, Mon Aug 26 2019, 04:54PM
have been reading/searching japanese papers last week - surprised that their english level is so low, and that weren't just some forum messages on the internets - that's official papers, like this one for example -
my eyes just broke while reading this
father dest, Mon Aug 26 2019, 04:54PM
have been reading/searching japanese papers last week - surprised that their english level is so low, and that weren't just some forum messages on the internets - that's official papers, like this one for example -
Proceedings of the 3rd Annual Meeting of Particle Accelerator Society of Japan
And the 31th Linear Accelerator Meeting in Japan (August 2-4, 2006, Sendai Japan)
Abstract
The main bending and quadrupole magnets in J-PARC 3GeV Synchrotron (RCS) that is controlled on rapid repetition of 25Hz excited follow the sine waveform. To realize of operation it, the magnet power supply was adopted of resonance type. Characteristic of resonance type power supply control, input response is not quickly because it transitional operation is very slow. On the other hands, the control must be slow continuous action to stabilize resonance balance.
my eyes just broke while reading this
Re: particle accelerators
Conundrum, Thu Aug 29 2019, 08:17AM
Conundrum, Thu Aug 29 2019, 08:17AM
Re: particle accelerators
jpsmith123, Tue Jun 16 2020, 04:01PM
For anyone interested in this subject, I recently found the following interesting paper by G. Dolbilov et al. This paper concerns a variant of the "Multibeam accelerator" where the high voltage is produced by a coaxial helical quarter wave resonator, apparently driven on the input side by an AC signal of a few kilovolts @ 100 kHz, rather than by an external primary winding. This way the housing can be made of metal. (I wonder if an external coil or magnet could be used to create magnetic insulation allowing for a higher output voltage without increasing the diameter)?
jpsmith123, Tue Jun 16 2020, 04:01PM
For anyone interested in this subject, I recently found the following interesting paper by G. Dolbilov et al. This paper concerns a variant of the "Multibeam accelerator" where the high voltage is produced by a coaxial helical quarter wave resonator, apparently driven on the input side by an AC signal of a few kilovolts @ 100 kHz, rather than by an external primary winding. This way the housing can be made of metal. (I wonder if an external coil or magnet could be used to create magnetic insulation allowing for a higher output voltage without increasing the diameter)?
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