Micro-cyclotron

This forum is for other possible methods for fusion such as Sonolumenescense, Cold Fusion, CANR/LENR or accelerator fusion. It should contain all theory, discussions and even construction and URLs related to "other than fusor, fusion".
User avatar
Chris Bradley
Posts: 2931
Joined: Fri May 02, 2008 11:05 am
Real name:

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by Chris Bradley » Fri Nov 02, 2012 5:58 pm

Frank, this is exactly why I developed/'invented' the 'inside-out yoke' - it was all about practicality, and assembly was certainly one factor:

download_thread.php?site=fusor&bn=fusor ... 1231363693

The flux from the magnets is taken into the centre rather than the outside. The technique allows one to simply keep on adding magnets to the edge of the assembly to increase the flux concentrated in the centre. In this way, what amounts to 'the pole pieces' are also the yoke itself, with the additional benefit that charged particles will strike the metal yoke plates instead of the magnets themselves.

(The 24 magnets, each of 22mmOD x 20mm, give me a 0.12T field in an operating space ~130mm diameter and 40mm high. Running a copper cored circuit would take some 400 to 800W to generate that sort of field, depending on whether you're running a Helmholtz coil type arrangement, which would be very impractical in a small amateur vacuum chamber. More magnets and less space the field could be set as desired.)

I also bought a couple of 60mm x 30mm magnets some years back for my project, but am truly fearful of having a bone-crushing accident with them (I think they were something like 400kg pull rated). It was actually the box they came in that encouraged me to think twice - they are marked with a skull and crossed bones!!

They have remained in that box they came in!

User avatar
Chris Bradley
Posts: 2931
Joined: Fri May 02, 2008 11:05 am
Real name:

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by Chris Bradley » Fri Nov 02, 2012 6:00 pm

Richard Hull wrote:
> the yoke would be a snap by assembling scrap large steel sections obtained from a scrap yard.
A 'snap' would very likely be the result (bones, metal, or even your pride when you end up with two magnets uselessly stuck together!) - these things are simply unbelievably difficult to manipulate. You would likely spend the same amount again, or more, on constructing a device that could mount these 6" magnets in a controlled manner to your yoke.

User avatar
Frank Sanns
Site Admin
Posts: 1605
Joined: Fri Jun 14, 2002 6:26 pm
Real name: Frank Sanns
Location: Pittsburgh, PA USA

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by Frank Sanns » Sun Nov 04, 2012 3:51 pm

I have been considering buying a pair of these large magnets. Many of the requirements for a yoke are gone with the NIB magnets. Laminated core is not necessary as there is no field variations therefore no eddie currents as are present in AC or unfiltered rectified DC. The most important difference is the self yoke function of the magnet itself. The permeability of air is quite poor in electric coil magnets but with NIB it is excellent. This should reduce or eliminate the need for a high permeability yoke and leave the design open to mechanical considerations and safety.

Frank Sanns

User avatar
Chris Bradley
Posts: 2931
Joined: Fri May 02, 2008 11:05 am
Real name:

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by Chris Bradley » Sun Nov 04, 2012 4:24 pm

Frank S. wrote:
> The permeability of air is quite poor in electric coil magnets but with NIB it is excellent. This should reduce or eliminate the need for a high permeability yoke and leave the design open to mechanical considerations and safety.

Frank, not sure what you mean here. Permeability of air is the permeability of air, isn't it!? I think you'll find that if you create a gap between two magnets without a yoke around them, you'll loose about a half of the possible field strength within the gap, because a half of the possible magnetisation that the magnets can do is wasted uselessly on creating a magnetic field within the air around the magnets from the flux from the reverse side of the magnets. If you put them in a yoke, it takes relatively little energy to align the yoke's magnetic domains, which means more field strength in the air-gap part of the circuit.

To avoid flux leakage from the yoke you will need a cross-section of yoke which is as big as the magnets cross-section area, reduced proportionately by the ratio of the saturation of the yoke and the surface magnetic flux of the magnets. This'd be around 1:2 for soft iron so you'll need a ~15.sq.in. cross-section yoke with these ~30sq.in. magnets.

Besides, you still have to mount and fix the magnets somehow. The easiest option might well be simply to mount them to a magnetic yoke below saturation. (If it is above saturation, the magnets may well jump off towards each other.)

User avatar
Frank Sanns
Site Admin
Posts: 1605
Joined: Fri Jun 14, 2002 6:26 pm
Real name: Frank Sanns
Location: Pittsburgh, PA USA

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by Frank Sanns » Sun Nov 04, 2012 8:46 pm

A coil of wire in itself is essentially all air. Wound on a high permeability core concentrates the field. A magnet is equivalent to the wire and the core.

George Schmermund
Posts: 262
Joined: Wed Aug 16, 2006 12:51 am
Real name: George Schmermund
Location: Carlsbad, CA

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by George Schmermund » Sun Nov 04, 2012 8:52 pm

Frank - Just for clarification I'd like to reiterate that I used the transformer approach specifically because of the laminations. Of course it would have been easier to build the yoke out of some soft iron bars that could be machined to size and bolted together, but that would have required that I use my machine shop instead of just the work bench out on the back porch.

The plan was to demonstrate that the project could be done with only a hammer, chisel, file, and bench vise. The transformer was easy to disassemble and separate into just the laminations. The center leg of each "E" shaped lamination was simple to remove using a wood chisel. When reassembled it was an easy task to file the center of the yoke flat.

In my eternal state of naiveté and self delusion I thought the demo would bring at least some folks to the realization that what appears to be an overwhelming project was really quite simple to achieve even without machine tools. Soon others would follow suit. Silly me!

Getting large magnets into the yoke (any yoke) is another matter....
Anything obvious in high vacuum is probably wrong.

User avatar
Richard Hull
Moderator
Posts: 11473
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: Micro-cyclotron or Just When You Thought it Was Safe to Go Back in The Water

Post by Richard Hull » Mon Nov 05, 2012 6:35 pm

I have easily mounted high flux NIB magnets in a surrounding yoke (double E core) with the central machined out E legs being the gap and magnet area. With two facing magnets it is easy beyond belief at most any size or field strength.

1. Know what your desired working gap is. Let's us 1" in our example.
2. Know the thickness of each magnet in the two magnet gap. Let us say 1.5" each
3. Know the distance between the yoke ends and the diameter of the magnets. Let us say the magnets are 3" in diameter and the width of the entire yoke opening is 6"

The ideal cutout of the central E region is thus 4"
get a large piece of 7/8" thick plywood that will slide through the E iron and the entire yoke. This would be a piece about 16"X5-7/8"

Determine the polarity of the magnets and mark them.

Place one magnet under the large piece of wood centered under the wood about 6" from one end of its 16" length and clamp this fixture to a table top. On top of this wood, place a small piece of aluminum flashing over the center region of the lower magnet.

Now place the second magnet on a 1/4" piece of plywood with the pole face downward on it opposite of the one under the clamped piece.

Now, carefully, holding this 1/4" sheet high over the clamped piece lower it rapidly towards the magnet under the thick sheet. Let the sheet go the instant you feel any force of pull and it will drop into place almost in line with the other magnet.

The slick aluminum sheet will allow you to slowly work out the 1/4" plywood allowing the magnet to come into direct contact with the 7/8" plywood sheet through the aluminum sheet.

Now carefully pull, push and tug the magnets into near perfect alignment with the 7/8" sheet separating them. (make sure that they are centered within the 5-7/8 width)

NOTE*** In cases of large diameter magnets of extreme field strength, two larger semi-circles of 1/2" thick plywood may have to be bolted with brass hardware to cover half of each magnet's pole face on the long side of the 7/8" board. This keeps the magnets from flipping up against the e-irons as they are inserted in the gap.

Slowly push the 7/8" sheet with magnets into the 4" E iron gap. At some point, the two magnets will flux link through the yoke and they will attach to their respect E iron sections in the gap, perhaps even yanking the board in it as well.

Now, with the yoke fixed in a vise or fixture, push each magnet fully onto its pole face. I have done this about 3 times in the past and it works great with no crushed fingers or heavy machinery involved. A wood board and a brass mallet can be used to coax the magnets to center with relative ease. The other magnet below may or may not follow. I prefer to ease them on to center alternately and slowly. All the time the 7/8" board is mostly now free to move, but keep it fully centered and in place until both magnets are pushed to be centered on their respective pole faces on the E iron, gap, yoke sections.

The 7/8" safety board can now be removed. They will now never connect together again provided no magnetic material is ever placed in the gap. (This is critical!!!) Once this is assembled never, ever place a screwdriver or other high permeability magnetic material in the gap for demonstration or test.

Now a good gauss meter and probe can be used to measure the field.

While each case is different, any wise person can adapt this procedure to fit their particular case.

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
Retired now...Doing only what I want and not what I should...every day is a saturday.

George Schmermund
Posts: 262
Joined: Wed Aug 16, 2006 12:51 am
Real name: George Schmermund
Location: Carlsbad, CA

Re: Micro-cyclotron

Post by George Schmermund » Wed Nov 14, 2012 4:43 am

Now that Richard has made the magnet/yoke assembly hazard seem to be a non-issue, I thought I'd rekindle the activity of making a micro-cyclotron chamber and Dee's as described in another post: download_thread.php?site=fusor&bn=fusor ... 1274837101

This construction project was also accomplished without having to use any machine tools. I keep hoping that someone will out pace me in an effort to get a micro-cyclotron up and running. This uC device could still be a potentially good neutron generator.
Anything obvious in high vacuum is probably wrong.

Tim Koeth
Posts: 3
Joined: Mon Jun 24, 2013 8:51 pm
Real name: Tim Koeth

Re: Micro-cyclotron

Post by Tim Koeth » Mon Jun 24, 2013 9:24 pm

Hey All,

If you are interested, here is a link to a detailed youtube video tour of our 1.2 MeV proton Cyclotron. It is kind of long, and we are not winning any awards for our acting skills, however it does cover all subsystems and operation.

http://www.youtube.com/watch?v=G2N-k5jz8bs

If you are building a cyclotron you might find it interesting.

Enjoy !

Post Reply