Search found 142 matches

by Liam David
Sat Aug 03, 2019 1:05 am
Forum: FAQs: Neutron - Radiation Detection
Topic: FAQ - Neutron Transport Simulation, Detector Calibration, and Shielding
Replies: 10
Views: 6376

FAQ - Neutron Transport Simulation, Detector Calibration, and Shielding

This FAQ (should it be raised to that status) will discuss neutron transport simulations and their applicability to fusors. This lengthy block of text is not a beginner's FAQ, so one should be well-versed in all topics in the Neutrons and Detection FAQs before continuing. While this is not a "freque...
by Liam David
Wed Jul 31, 2019 11:09 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Joe Gayo's lab tour
Replies: 69
Views: 27476

Re: Joe Gayo's lab tour

Having my enthusiasm for detecting tritium crushed in the post (http://www.fusor.net/board/viewtopic.php?f=50&t=12900) Robert mentioned, I think I can safely say that strange light-atom combinations are producing the false positives. About a week ago I measured the partial pressure of m/z = 6 to be ...
by Liam David
Wed Jul 24, 2019 7:21 pm
Forum: Advanced Technical Discussion Area
Topic: Tritium from Deuterium Lecture Bottle? (Edit: Misattribution of D3+ Factor)
Replies: 4
Views: 371

Re: Tritium from Deuterium Lecture Bottle? (Edit: Misattribution of D3+ Factor)

My RGA, which is the Spectra Vacscan Plus (late 90's to early 2000's) with a 100amu range, does have a multiplier, though the maximum operating pressure for it is 2e-6. For all purposes but measuring the base pressure of my system (9e-8torr) I use the Faraday cup. I managed to score the RGA and all ...
by Liam David
Wed Jul 24, 2019 4:10 am
Forum: Advanced Technical Discussion Area
Topic: Tritium from Deuterium Lecture Bottle? (Edit: Misattribution of D3+ Factor)
Replies: 4
Views: 371

Re: Tritium from Deuterium Lecture Bottle?

Ah, as per usual the explanation is more nuanced. I am still surprised that 50% of the deuterium pressure (only in the RGA, of course) was D3+. According to one paper (http://www.forensic-isotopes.org/assets/IRMS%20Guide%20Finalv3.1_Web.pdf), "The H3+ factor should not exceed 10ppm/nA [...]" which i...
by Liam David
Tue Jul 23, 2019 11:49 pm
Forum: Advanced Technical Discussion Area
Topic: Tritium from Deuterium Lecture Bottle? (Edit: Misattribution of D3+ Factor)
Replies: 4
Views: 371

Tritium from Deuterium Lecture Bottle? (Edit: Misattribution of D3+ Factor)

This morning, while I was evacuating my fusor chamber and differentially pumping the RGA for high-pressure measurement, I cracked the needle valve on the still-pressurized deuterium gas line and immediately noticed a large peak at m/z = 6. The pressure in the main chamber was around 10mtorr and that...
by Liam David
Mon Jul 22, 2019 11:25 pm
Forum: Images du Jour
Topic: I'm back, and fusing
Replies: 5
Views: 4258

Re: I'm back, and fusing

FBM printing leaves too many irregularities and any hope of preventing breakdown would require 100% fill. That would really take some time to print. I suspect that SLA would work better, but I don't know about the dielectric strength of the resin. ABS is pretty bad at ~500V/mil, but that's likely mu...
by Liam David
Thu Jul 18, 2019 1:53 am
Forum: Images du Jour
Topic: I'm back, and fusing
Replies: 5
Views: 4258

Re: I'm back, and fusing

Funny you should ask that. I 3D printed a connector out of ABS a couple years ago but once I pushed ~35kV there were arcing issues. It finally bit the dust just a couple days ago and left a carbonized trace. The socket cannot be run to any appreciable voltage unless there's a proper connector instal...
by Liam David
Mon Jul 15, 2019 10:49 pm
Forum: Fusor Construction & Operation (& FAQs)
Topic: Transparent Ceramic Viewports
Replies: 8
Views: 4304

Re: Transparent Ceramic Viewports

This is not to shoot down your idea to use exotic (and likely expensive) materials, but regarding ion beam viewport damage there are simpler solutions. First, just don't orient the grid such that gaps are inline with glass or ceramic. It's localized heating and large spacial and temporal thermal gra...
by Liam David
Mon Jul 15, 2019 2:37 pm
Forum: Images du Jour
Topic: Ion Beams Destroying Viewports
Replies: 5
Views: 3454

Re: Ion Beams Destroying Viewports

The turbo's fine as it was at 66% speed and the inrush was only to ~10 torr. I isolated it immediately after noticing the problem and didn't know whether the viewport would still implode. The viewport has since been replaced with a blank and I have again done fusion, but I added some magnets on the ...
by Liam David
Sat Jul 13, 2019 11:59 pm
Forum: Images du Jour
Topic: Ion Beams Destroying Viewports
Replies: 5
Views: 3454

Ion Beams Destroying Viewports

This is yet another demonstration of why fusor chambers should not be made of glass or other brittle materials. It may also serve as a warning for those building small chambers based on 2.75" conflat systems. I have a 2.75" conflat 6-way chamber with two viewports, one on axis with a graphite and tu...