RMR-Farnsworth Fusor 5

For posts specifically relating to fusor design, construction, and operation.
User avatar
Steven Sesselmann
Posts: 2111
Joined: Thu Aug 11, 2005 1:50 am
Real name: Steven Sesselmann
Location: Sydney - Australia
Contact:

Re: RMR-Farnsworth Fusor 5

Post by Steven Sesselmann » Sat May 04, 2013 10:28 pm

Martijn,

Very impressive rig, only noticed this post today, as the old fusor.net has been inaccessible in Australia.

The picture from your data logger caught my eye, as I am using a similar setup, and I notice you have a current limiting power supply, i.e. the voltage changes, but the current remains steady at 5ma.

Have you compared fusion rates using the current limiter, as opposed to operating within the natural voltage current fluctuations?

My personal feeling was that the current limiter was detrimental to fusion rates, but I never proved this, before decommissioning my rig.

Posted below is an image from Labview, where pressure(yellow), voltage(red) and current(pink) were plotted. Unfortunately I had no neutron logging, but my recollection is that more neutrons were produced, during in current climb periods. These exponential rises in current were natural phenomenon, making it difficult to control the rig.

Steven
Attachments
120729_labview.PNG
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG

User avatar
Martijn Rambonnet
Posts: 18
Joined: Thu Mar 17, 2011 11:34 am
Real name:
Contact:

Re: RMR-Farnsworth Fusor 5

Post by Martijn Rambonnet » Mon May 06, 2013 9:19 pm

Hi Steven,

We have not yet tried to operate the fusor in the modes you described. As I think every fusioneer has experienced it is much easier to control the voltage than to control the current by varying the pressure (which is of course logical).

We will give it a try to operate the supply in constant voltage mode and let the current vary within boundaries.

If we can get the count rates up we will make some plots to see how the neutron flux correlates with current and voltage changes.

Also the deuterium valve we use for fine pressure control is electrically actuated but not yet connected to any pressure feedback. Once that is finished it might also be interesting to see how current and voltage varies at constant pressure. It seems that the rises in voltage are caused by decreases in outgassing as the system stabilizes.

User avatar
Martijn Rambonnet
Posts: 18
Joined: Thu Mar 17, 2011 11:34 am
Real name:
Contact:

Re: RMR-Farnsworth Fusor 5

Post by Martijn Rambonnet » Sat Sep 07, 2013 8:55 am

To provide some closure to this thread: We found that the low neutron results could be primarily explained by DH contamination, probably due to H2O dissolving into the D2O from the air. Our D2O supply was running low and when using too small amounts of D2O in the PEM cell a steadily increasing DH peak (3 a.m.u) on the RGA graphs could be observed, which could be removed by adding sufficient D2O to the PEM cell.

We did not find any other contamination as for example C2O as suggested by Peter.

Also the performance of the He3 preamp was improved. The pcb inside our metal preamp case was not stiffly enough connected and acted as a microphone when it was hit or tapped on (probably a change in capacitance between the electronics and the metal case). Also our long cables proved to cause unnecessary interference.

We have no further formal fusion results although some initial spectroscopy results can be seen on our website: http://radiantmatter.com/content/news/i ... py-results When we get more detailed results we will ofcourse post a full report to fusor.net.

Currently we are working on modifying the setup. We have milled a CF conversion flange and have modified the table to replace our diffusion pump with a turbo pump loaned to us. Also the Farnsworth Fusor setup will be moved to a 6" side tube to free up the main chamber for the polywell setup.
In the mean time we are also working on the Polywell coil cases, a Langmuir probe, cleaning (sanding/scrubbing) all parts and converting temporary nitrile/viton gaskets to metal seals in preparation for the Polywell experiments at lower pressures.

User avatar
Richard Hull
Moderator
Posts: 12513
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: RMR-Farnsworth Fusor 5

Post by Richard Hull » Mon Sep 09, 2013 4:45 pm

This is a great follow up on the system at you university. Most important is your finding about low electrolysis cell DH contamination. This finding has not been reported and is good data for those wishing to operate a D2O electrolysis gas sourcing system. Again, we can't thank you enough for your reports and participation in fusor.net. You are well placed to actually investigate the Polywell as you have done fusion with a simple fusor and know what is a good signature of fusion and what is not. Keep us informed.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Post Reply