Search found 882 matches

by Rich Feldman
Wed Nov 13, 2019 6:23 am
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Idea for Rhodium Target
Replies: 1
Views: 22

Re: Idea for Rhodium Target

Your work seems very promising to me. But what purpose is served by the boric acid? Does it improve the mechanical properties of powdered metal pellets, or have another use in the pressed-pellet business? I think it's bad to have boron anywhere close to where you want lots of thermal neutrons. Since...
by Rich Feldman
Sun Nov 10, 2019 11:25 pm
Forum: Items For Sale
Topic: [REQUEST] HV Power Supply or +75 kV Transformer
Replies: 4
Views: 2479

Re: [REQUEST] HV Power Supply or +75 kV Transformer

It's said that resourceful amateurs made working fusors before the Internet existed. Kids today think anything you can't click-to-buy within 5 minutes online is "hard to get". For intangible stuff like answers to questions, they think "due diligence with one's own searches" amounts to single-digit m...
by Rich Feldman
Sat Nov 09, 2019 8:27 am
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 61
Views: 39020

Re: lab electromagnet from scratch

Permanent magnet measurement exercise is complete. Ought to be good practice for using fluxmeter to learn about flux leakage in Big Three Inch electromagnet project. I told the details step by step on another forum, as they unfolded: https://highvoltageforum.net/index.php?topic=819.0 That's differen...
by Rich Feldman
Tue Nov 05, 2019 3:42 am
Forum: Announcements and Site Administration Topics
Topic: Not good news about the lost links on the site
Replies: 14
Views: 392

Re: Not good news about the lost links on the site

Please don't lose sleep over it.
I did some spot checking of posts from 15 years ago. Some images "no longer present", some are just fine.

Any chance there are 3rd party backups somewhere?
by Rich Feldman
Sat Nov 02, 2019 9:23 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 61
Views: 39020

Re: lab electromagnet from scratch

First real measurement of the radial flux density, B, indicated 0.60 teslas. That's much lower than I'd guessed at the beginning. It's roughly consistent with last night's initial SWAG, based on a copper pipe's physical parameters and rate of descent, judged by eye. I still don't know the sign, whic...
by Rich Feldman
Thu Oct 31, 2019 10:55 pm
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: lab electromagnet from scratch
Replies: 61
Views: 39020

Re: lab electromagnet from scratch

Not sure whether to dust off this old thread, or start a new one for a tangential topic. The next step for BTI magnet project is to measure the flux distribution, quantitatively. How will the fraction which fringes out or leaks away go up, as the air gap length increases from zero to 1 inch? It'll b...
by Rich Feldman
Mon Oct 21, 2019 3:25 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Radon - much ado about nothing.
Replies: 2
Views: 330

Re: Radon - much ado about nothing.

Thanks for the pointer, Richard. Anybody here have experience with, or recommendations for, airborne-radon test brands? (Collection kit + lab to which you send the sample) California is one of the states that requires test providers to be certified. One web search brought up a kit sold by Home Depot...
by Rich Feldman
Sun Oct 20, 2019 12:44 am
Forum: Other Forms of Fusion - Theory, Construction, Discussion, URLs
Topic: Use of pure natural lithium in a high-yield fusor
Replies: 3
Views: 342

Re: Use of pure natural lithium in a high-yield fusor

Josh, it's best to do that kind of experiment with a quantitative forecast about the outcome. Exercises for you, starting with overly simple ones: 1. Suppose you have a 1 cm thick slab of natural Li, with some flux of thermal neutrons coming from one side. What fraction of the neutrons will be stopp...
by Rich Feldman
Wed Oct 16, 2019 3:26 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Non-Corrosive and/or Dielectric Liquid Cooling?
Replies: 16
Views: 1107

Re: Non-Corrosive and/or Dielectric Liquid Cooling?

Last year I used unpressurized liquid propane as a freezing bath, outdoors in a well ventilated area, with excellent success. Started with a thermos full, drawn from a BBQ tank so old it still has a POL valve. Glad to be with Dennis on a safety thing! Am reminded of one classic HV high bandwidth sco...
by Rich Feldman
Mon Oct 14, 2019 12:33 am
Forum: High Voltage - Fusor Input Power (& FAQs)
Topic: Non-Corrosive and/or Dielectric Liquid Cooling?
Replies: 16
Views: 1107

Re: Non-Corrosive and/or Dielectric Liquid Cooling?

Please excuse one answer to a question addressed to somebody else. Some of my co-workers worked on a Fluorinert-cooled instrument during years when I worked elsewhere, and I will ask about it on Monday. Meanwhile, LMGTFY. Found a lot here: https://detector-cooling.web.cern.ch/detector-cooling/data/3...