Possible Polywells

15 11 2010

All photos.

This diagram shows the possible coil configurations of the superconducting tape. Going from minor radius 2 mm at top to minor radius  7 mm at bottom.

I used the very cool XRVG to generate SVG diagrams from ruby.

Liquid Nitrogen

28 09 2010

All photos.

Gearing up for another test of the superconducting magnet. So liquid nitrogen.

What is this… Halloween?


27 09 2010

All photos.

I’m back from a refreshing vacation. Started by cleaning up my desk:

Stuart gave me this cool old small parts drawer:

I’m going to start by taking another crack at the persistent switch for the superconducting magnet.

Also, if you have been trying to get a hold of me… now is a good time.

Arcam EBM fabrication

19 10 2009

I’m exploring the Arcam EBM process for fabricating the magrid.

Our current scale is within their build envelope (250 x 250 x 400 mm and 350 x 350 x 250 mm).

Their process creates a fully solid / fully melted part using Ti6Al4V Titanium Alloy.

Titanium is non magnetic (paramagnetic). GOOD

Titanium has low outgassing (I _assume_). Not seeing good information on this, but I see articles about low outgassing. GOOD

The fully melted part should be vacuum tight. GOOD

Titanium can be welded, but it’s complicated. Gas shielding is required. WORKABLE

Titanium is difficult to machine. It requires specialized tools. It’s tough and springy. Too hot and it reacts chemically. The magrid part is likely too delicate to be secured for machining. We can still lap sand the faces for better mating. BAD/WORKABLE.

Titanium is strong. GOOD

Titanium is beautiful. GOOD

The part would be highly conformal. I do not expect the warping as with the prometal magrid. GOOD

Price. This same part would cost around $2500. Better get it right the first time. WORKABLE

Although it’s a path fraught with peril, it could lead to a fully functional superconducting magrid.

Superconducting Magrid IRL

30 09 2009

WOW. Check out this part we just got from prometal:


There is some slight warping, so the lid doesn’t fit as tightly with some of the faces. This can be corrected with machining, but some extra material would need to be built in.


It really helps to hold the shape in your hands. Amazingly this process is inexpensive. These two pieces cost ~$110. So we can afford to do about 10 iterations, more if necessary. Pretty cool.

Previously we used the 420 Stainless Steel +Bronze, which is magnetic. This time we used the 316 Stainless Steel + Bronze hoping it would be non-magnetic –  but unfortunately it is magnetic.

With superconducting cable:


SC Magrid Feedthrough Simplification

31 08 2009

Doing more thinking on the superconducting magrid feedthrough. Rather than have a bend between the magrid and a centered feedthrough, it would probably be easier to make a custom conflat blank with an off center 2.75″ pass though welded on. Like this:


The part would looks something like this (via MDC):


Standoff for Superconducting Magrid

29 08 2009

I’ve been doing some brainstorming on the standoff for the superconducting magrid. This is a messy problem! You need a cryogenic feedthrough that is also a high voltage standoff. Then you need to pass in the YBCO superconducting cables, and wiring for the persistent switch.

Yesterday I realized that we can get most of the way there by welding together two off the shelf components:

standoff_feedthroughThis diagram refrences parts 9812107 and 9611005 from insulatorseal which is a subsidiary of MDC Vacuum. I’ve sent this drawing to insulatorseal for a quote. One problem is that part 9611005 is only rated up to 6kV so we will need a custom variant to get to the 10kV to 40kV range.

The idea with this setup is that the high voltage could come through a standard HV feedthrough and connect to the insulated tip of this feedthrough via a connecting wire:


New STL for Superconducting Magrid

23 08 2009

Created a new STL of the superconducting magrid using a tolerance of 0.01mm. It looks much smoother:


If you looks closely you can see the faceting. Also took some time to refactor the code that generates these shapes. I added a temp folder and a parts folder to keep the main directory free of trash. Now the resulting STL and PNG filenames include the hash tag of the current git HEAD so you can connect an STL file to the code that generated it. You can find the branch I’m working on here.

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