Search found 30 matches

by Chris Mullins
Sat Jul 21, 2018 11:47 am
Forum: Announcements and Site Administration Topics
Topic: How did you find our Fusor forum?
Replies: 8
Views: 778

Re: How did you find our Fusor forum?

I found this site from a google search on fusors, after my son showed me the infamous Make magazine demo fusor article. Count me in for a fund drive. It's difficult to overstate how much accumulated knowledge is here in old threads, and how valuable it is for a novice actually trying to learn and bu...
by Chris Mullins
Sat Jun 16, 2018 9:11 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Atlas of Neutron Capture Cross Sections
Replies: 3
Views: 1247

Re: Atlas of Neutron Capture Cross Sections

Thanks, just snagged that one for $4 (including shipping) at Abe. I know it's nothing new these days, but I'm still amazed at how cheap these books are, packed with timeless information. A quick search for this book turned up Richard's post from 2008 ( http://fusor.net/board/viewtopic.php?f=21&t=813...
by Chris Mullins
Wed Jun 13, 2018 12:53 am
Forum: Books & References
Topic: Vacuum Engineering Textbooks
Replies: 4
Views: 2054

Re: Vacuum Engineering Textbooks

Thanks for the recommendations, I was able to grab all four for even less than those prices, from Abe books and Amazon. Now begins the 20-50 day wait for shipping from the UK ....
by Chris Mullins
Tue May 29, 2018 11:58 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 58
Views: 18272

Re: lab electromagnet from scratch

Yeah, well I did have a long weekend to work on it :) Rich pointed out offline that I may have two flaws in my FEMM model that could be roughly canceling each other out, so that the results happen to be close to correct on some of those results. I'll try the axisymmetric model this weekend, and vary...
by Chris Mullins
Tue May 29, 2018 12:07 am
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 58
Views: 18272

Re: lab electromagnet from scratch

Mark, I can second the recommendation for FEMM's Lua scripting - it was very easy to that working. I simulated the "MCM", as Rich has named it, this weekend. Two immediate observations: 1) FEMM works pretty well, and 2) I should have simulated the MCM before actually building it. I drew a 2D slice o...
by Chris Mullins
Fri May 18, 2018 11:13 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 58
Views: 18272

Re: lab electromagnet from scratch

Richard,

No doubt I still have much to learn!

I was thinking it could be significant since my difference was much smaller (0.5% or less) once I had both coils in place, compared to a single coil on one pole.
by Chris Mullins
Fri May 18, 2018 6:04 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 58
Views: 18272

Re: lab electromagnet from scratch

Rich, Can you power the coil with an adjustable, constant current source, and measure the field strength at the face of each pole? When I only had one coil, I had around a 3 to 5% difference at each pole face, across a 1.42" gap (e.g. I'd read 144.9 mT on the bottom pole face (the one with the coil)...
by Chris Mullins
Tue May 15, 2018 1:58 am
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 58
Views: 18272

Re: lab electromagnet from scratch

Rich, Having an adjustable pole gap would be really useful. That feature was way beyond my construction abilities. You mentioned another temporary winding, at 100V and 100A to get 1 Tesla with a 1" gap. Even with much less current on a temporary winding, if you can adjust the gap continuously you co...
by Chris Mullins
Tue May 15, 2018 1:39 am
Forum: Images du Jour
Topic: cyclotron electromagnet - 1 Tesla achieved
Replies: 2
Views: 820

Re: cyclotron electromagnet - 1 Tesla achieved

Rich, Good question on skin depth. I'm not sure about 1018 steel, but iron is about 80 mils at 1 Hz. My gaussmeter doesn't have an analog or digital output, so I have to video a test run and transcribe the numbers later. I ran a test by putting a (much abused) resistive shunt in series with the coil...
by Chris Mullins
Sun May 13, 2018 8:47 pm
Forum: Images du Jour
Topic: cyclotron electromagnet - 1 Tesla achieved
Replies: 2
Views: 820

cyclotron electromagnet - 1 Tesla achieved

Well, the embarrassment of a naked pole in our cyclotron magnet is finally over - the second coil is wound and installed. Winding 900 feet of 1/4" ACR copper tubing isn't fun, but far worse is sliding 900 feet of fiberglass sleeving over it, a couple of inches at a time (it was truly a family affair...