Search found 190 matches

by Dan Knapp
Tue Jul 17, 2018 2:48 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Somebody got quite a deal on eBay
Replies: 1
Views: 67

Somebody got quite a deal on eBay

There was a Ludlum 15 neutron detector with two helium-3 tubes and moderators that sold for $510 on eBay yesterday. (search ludlum 15 neutron in completed listings to see it; the link won't work for completed listings) This detector is a combination geiger probe/neutron detector. One of the neutron ...
by Dan Knapp
Thu Jul 05, 2018 1:42 pm
Forum: Neutrons, Radiation, and Detection (& FAQs)
Topic: Maximus Energy NEUTRON-PRO neutron detector
Replies: 0
Views: 282

Maximus Energy NEUTRON-PRO neutron detector

There is a neutron detection system called the "Maximus Energy NEUTRON-PRO touch-screen neutron detection and spectroscopy system in Faraday enclosure" being sold on eBay for $1695. It uses a He-3 tube and is totally self contained in a Faraday shield. This would seem to be a good solution to the el...
by Dan Knapp
Thu Jul 05, 2018 11:12 am
Forum: Fusion --- Past, Present, and Future
Topic: First IAEA Workshop on Fusion Enterprises
Replies: 2
Views: 334

First IAEA Workshop on Fusion Enterprises

The First IAEA Workshop on Fusion Energy was held recently in Santa Fe. The presentations are now posted at: https://nucleus.iaea.org/sites/fusionportal/Pages/Enterprises/2018/General-Info.aspx One I found particularly interesting was about work at the University of Wisconsin revisiting the mirror m...
by Dan Knapp
Wed Jul 04, 2018 11:58 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Ballast resistor construction
Replies: 11
Views: 794

Re: Ballast resistor construction

Finally got around to using the ballast resistor today. It worked fine, and I didn't see any signs of discharge (although I wasn't working above 20 kV). The idea of a putting liquid crystal thermometer strip inside the tube didn't work - too hard to see - so I just put a dial thermometer on top that...
by Dan Knapp
Sun Jun 24, 2018 11:47 am
Forum: Vacuum Technology (& FAQs)
Topic: Atmospheric pressure hydrogen storage experiments
Replies: 5
Views: 1166

Re: Atmospheric pressure hydrogen storage experiments

It occurred to me that the balloon could be useful even for those using deuterium from a cylinder. When one uses a closed rigid buffer volume with cylinder deuterium and bleeds it into the fusor, there is a constantly declining pressure in the buffer, which requires readjustment of the leak to maint...
by Dan Knapp
Fri Jun 22, 2018 12:53 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Ballast resistor construction
Replies: 11
Views: 794

Re: Ballast resistor construction

I failed to respond to John’s comment. If I encounter discharge problems, I will go to a larger acrylic tube and add three corona rings like you show in your photo. The photo from the Japanese lab shows two corona rings. They go over 100kV with this system in air. Incidentally, this is the system wh...
by Dan Knapp
Fri Jun 22, 2018 12:38 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Ballast resistor construction
Replies: 11
Views: 794

Re: Ballast resistor construction

I have a 60 kV / 60 ma power supply, but I don’t plan to go to more than about 40 kV. I’m only using a 30 kV feedthrough. I have solder blobs on the resistor tabs, but the putty is a good suggestion. I realize the resistance and wattage are probably twice what would normally be needed, but I was goi...
by Dan Knapp
Thu Jun 21, 2018 7:28 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Ballast resistor construction
Replies: 11
Views: 794

Ballast resistor construction

After failing to find any suitable large high wattage resistors at hamfests and flea markets, I finally ordered some from China on Amazon. I bought two 100K/100W ceramic wirewound resistors for $10.67 each (see attached photo). These aren't specifically rated for high voltage use, but I figured the ...
by Dan Knapp
Sun Jun 10, 2018 12:41 am
Forum: Images du Jour
Topic: Sharing hamfest booty images
Replies: 22
Views: 3555

Re: Sharing hamfest booty images

I just visited the legendary Silicon Valley Electronics Flea Market in Fry’s parking lot in Sunnyvale. Compared to the season’s first MIT flea market, I would have to rate this one much better (although Andrew reported that the second MIT Flea had a much better turnout than the first one that I atte...