SmCo Grid for Deuteron Deflection

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Joshua Guertler
Posts: 83
Joined: Fri Apr 21, 2017 2:59 pm
Real name: Joshua Guertler

SmCo Grid for Deuteron Deflection

Post by Joshua Guertler » Mon Apr 29, 2019 8:13 pm


In the hopes of reducing the amount of collisions that occur between my grid and the incoming deuterons, I have been searching and other sites for potential manners to optimize grid transparency and deflect 40 keV deuterons.

After doing so, I came across a few sources, one of which included an old post by Jeroen Vriesman back in 2015 (see here: viewtopic.php?f=18&t=10265&p=68448&hilit=SmCo#p68448).

In the post linked above, the OP talks more about how he desires to use this for reducing the current pull of the fusor. However, it has occurred to me that the magnetic field produced by the magnets may be used to deflect the trajectories of deuterons in the slightest fashion to reduce collisions with the grid.

Thus, I propose that a typical grid configuration comprised of two loops made of nickel-coated samarium cobalt may be used to reduce collisions with the grid. The new grid would be made up entirely of this SmCo magnetic material (beyond the nickel layer), thus, the high voltage would be applied to it. The grid would look somewhat like the item below:
fusor grid.jpg
I am considering this design for my magnets, but perhaps without the center/equatorial ring.
fusor grid.jpg (12.95 KiB) Viewed 974 times
The apparatus that I am using has a -40 kV 400 W power source (the likes of which are still being modified). The magnetic SmCo grid will have an outer diameter of 1.25” and shall be placed in a stainless steel hemisphere of a 6” outer diameter. At the moment, I am not planning on using an ion gun, but its addition may prove tempting in the future.

If I succeed in getting this grid operational, I am planning to move onto more geometrically transparent designs (such as those modeled by the University of Wisconsin-Madison). Thus, I will be able to determine if the use of magnetic materials (SmCo magnets) are able to decrease the number of collisions with the inner grid wires.

Thus, I was curious if the individuals on this forum (who are far more experienced and knowledgeable on this topic than I) have any input on my design and whether or not the use of magnets would do any useful work to prevent deuterons from colliding with the grid.

If it happens to be that my proposed magnets are of no use for deuterons deflection, I was curious if they might be useful for some other purpose (i.e. decreasing current draw). Thank you.

Joshua Guertler

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Rich Feldman
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Real name: Rich Feldman
Location: Santa Clara County, CA, USA

Re: SmCo Grid for Deuteron Deflection

Post by Rich Feldman » Tue Apr 30, 2019 4:12 am

Interesting idea, Joshua. Reminds me of original polywell fusors (?) with ring-shaped electromagnet coils inside.

Issue 1. How do you propose to orient your permanent magnets? All north poles up? All north poles away from the sphere center? Each arc magnetized along its length, or transversely in the plane of the spherical surface?

How will the resulting static magnetic field be oriented in space outside the magnets? How is it supposed to deflect moving ions away from hitting the grid? Do you understand the basic f = q times (v cross B) formula for force on a charged particle in a magnetic field?

There's an inherent magnetic field from the HV current in any fusor, but its magnitude is negligible compared to, say, the geomagnetic field, or the weakest intentionally permanent magnets.

Issue 2. How do you propose to cool the grid, to keep high energy magnetic materials from overheating? SmCo is much more tolerant than NdFeB, but its useful temperature range is all lower than the useful temperature range of ordinary soldering irons.
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