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Re: Joe Gayo's lab tour

Posted: Mon Jul 29, 2019 2:58 am
by Joe Gayo
I find it interesting that even after an hour it’s still there and it didn’t show up in lower fusion rate runs

What’s an alternate explanation for mass 5 if tritium isn’t present ?

Re: Joe Gayo's lab tour

Posted: Mon Jul 29, 2019 4:32 am
by Joe Gayo
@Dan - I’m trying to complete the following list of possible detected species that’s relevant for fusors

AMU: Possible Species
1: H+
2: H2, D+
3: H3, HD, 3He, T+
4: D2, 4He, TH
5: D2H+(?), TH2+(?), DT
6: D3+, T2, C+

19: DHO, H2OH+, NHD2, CH3D
20: D2O, ND3, CD4
21: D2OH+, DTO
22: D2OD+, T2O

Re: Joe Gayo's lab tour

Posted: Mon Jul 29, 2019 8:26 pm
by Richard Hull
Tricky work! The RGA in the depths of what a multiplier can sniff out below 10e-7 might be showing stuff that can't be produced or exist outside of an active fusor environment. Still, it's fun to try and figure it all out. We really don't know what stressed molecular chemistry might slap together in rare moments in vacuuo, and in an energetic environment.

Good start on a listing. My head hurts just reading that first pass of molecular offerings.

Richard Hull

Re: Joe Gayo's lab tour

Posted: Mon Jul 29, 2019 11:17 pm
by Joe Gayo
This search helps: https://webbook.nist.gov/chemistry/mw-ser/

The strong presence (2.86E-7 Torr) of 5 amu correlated with high fusion rate runs temps me to believe this is DT.

Re: Joe Gayo's lab tour

Posted: Tue Jul 30, 2019 12:20 am
by JoeBallantyne
Half of the D-D fusion that happens should be producing T + p. The other half is producing He3 + n.

Some of the T that gets produced may also get burned. So you should see some 14Mev neutrons coming out if you are actually burning DT.

Probably most of the T is getting buried in the walls of your fusor, since it will not be confined by 90KV.

But if you bury enough T in the walls, some of it will likely outgass.

I wouldn't be surprised if you see some DT after a long high power run. Figuring out how much you should be seeing will likely be non trivial.

Joe.

Re: Joe Gayo's lab tour

Posted: Wed Jul 31, 2019 9:13 pm
by Robert Dwyer
Personally I doubt this Tritium, but I think it is rather some artifact of the rga. In other systems I have used an rga on (not fusors), I have seen the peak at 6 before when working with deuterium. Remember the rga is ionizing, so there is the possibility of D3 ions being created as well as some other interesting combination of low-Z elements, which I think is what is going on here. I find it hard to believe that enough Tritium is being produced to be detected by these instruments.

*EDIT: It appears this was already discussed and brought in another thread by Liam David. Sorry to reiterate something that was brought up before in another post.

Re: Joe Gayo's lab tour

Posted: Wed Jul 31, 2019 11:09 pm
by Liam David
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 equal in height to that of deuterium at m/z = 4, and incorrectly attributed it to tritium. While my fusor produces orders of magnitude less fusion than Joe's system, my claim was based on tritium enrichment in deuterium lecture bottles (http://fusor.net/board/viewtopic.php?f= ... ium#p36510). It was in fact the RGA ion source producing D3+, and I have observed a small peak appear at 6 every time since. My RGA is much older than the SRS models, so it it doubtless less sensitive, but I have occasionally seen noise at m/z = 1, 3, 5, 6 resulting from various protium/deuterium combos.

Some math as to the feasibility of detecting tritium with an RGA:

Let's assume a 60 minute run at 3.03e7n/s (from the RGA plot title above) for a best-case scenario. An equal number of tritium atoms are produced, so we have 60^2*3.03e7 = 1.09e11 produced in total. Now I will assume that there are no losses of any sort, i.e. the tritium recombines and does not get pumped out, embed itself in the chamber walls, etc. This it entirely unrealistic by every conceivable account, but I think we will find that even this situation fails to allow for statistically significant tritium detection. Using everyone's favorite equation of state, we obtain a pressure in a ~1L chamber at 323K (50C) of
P = NkT/V = (5.45e10 T molecules)(1.38e-23 [units])(323K)/(1e-3m^3) = 2.43e-7Pa = 1.823e-9torr.
This is certainly within the sensitivity of an RGA (mine can detect to e-11 and the SRS models can go down to e-13, I think) but now we return to the assumptions and realize we're probably not within six orders of magnitude. Even if we get lucky, the noise floor from various light atom combinations and the tritium already present in the lecture bottle (~1.29ppb max in a 50L lecture bottle, which, in my fusor, could theoretically produce a partial pressure of 6.5e-9torr) drowns out any hope of fusion-produced tritium detection.

Maybe Doug could chime in here as, if I remember correctly, he claims to have detected tritium once with an RGA.

Either way I think the RGA will be much more valuable in determining the purity of the plasma, especially regarding water, mechanical pump hydrocarbons, o-ring grease, and any number of other charge thieves.

Perhaps, as per Richard's recommendation in my post, we should write an RGA FAQ. There seems to be a growing interest, especially among those who are serious in doing research with their fusor.

Re: Joe Gayo's lab tour

Posted: Mon Sep 09, 2019 12:52 am
by Joe Gayo
New Record @ 4:46pm PST-

Cathode Voltage: 97932V (Ballast Resitor 100k Drop Subtracted)
Cathode Current: 14.38 mA
Pressure (D2): 1.865 Pa (Base Pressure Before Run: 9.866E-5 Pa)
Calibrated TIER: 4.217 E+7 n/sec
Q: 3.50 e-8

I believe n/sec and Q are amateur records.

Re: Joe Gayo's lab tour

Posted: Mon Sep 09, 2019 1:09 am
by Bob Reite
Having lots of Volts really makes the difference. I believe that the former record holder was operating at around 80 KV

Re: Joe Gayo's lab tour

Posted: Mon Sep 09, 2019 2:33 am
by Richard Hull
Fabulous work, Joe!

Richard Hull