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Tubbs Accelerator Talk: 2015 HEAS

Posted: Sun Oct 04, 2015 10:13 pm
by RobertTubbs
This is a .pdf of my accelerator talk presented at HEAS 2015.

-RT

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Sun Oct 04, 2015 11:06 pm
by Steven Sesselmann
Robert,

Thanks for posting, wish I was there for the talk. Your electron suppression circuit is good, I might copy that if you don't mind.

How did you arrive at ∆V=1400V ?

Steven

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Sun Oct 04, 2015 11:32 pm
by RobertTubbs
Steven,

The zener circuit is a common approach, while that particular picture was done by Ying Wu, I made some corrections in photoshop.

I believe Ying Wu's collection of zeners added up to ~1400V, and that was why the value was chosen.

The ∆V for a successful zener suppression system can be as low as a couple hundred volts.

-RT

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Mon Oct 05, 2015 12:04 am
by Mike Beauford
Robert,

That's a super neat setup you have! Are your neutron production run's very stable with this setup with the occasional flair up every now and then?

Mike Beauford

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Mon Oct 05, 2015 1:24 am
by RobertTubbs
Hi Mike,

Thank you!

It's a very stable and prolific source of neutrons, what few occasional increases/drops in vacuum chamber pressure that occur are caused by variations in pressure within my electrolysis system (soon to be replaced by another lecture bottle of deuterium gas.) Tank gas and a good regulator eliminate most of the increases/drops since the back pressure behind my micro-metering valve remains constant.

-RT

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Mon Oct 05, 2015 1:54 am
by Andrew Robinson
Excellent presentation Robert and again bravo on your design and construction. You really have a professional looking setup there. Very nice work.

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Mon Oct 05, 2015 2:04 am
by Richard Hull
I'll second Andrew's kudos. Robert knows his system and answered all questions put to him by the many interested people during his talk. Again, well done and well delivered.

Note: We played hell getting a computer that would work his power point demo, but the third laptop was charm. Sorry 'bout the snag Robert.

Richard Hull

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Wed Oct 07, 2015 3:58 pm
by Dennis P Brown
Mr. Tubbs' talk was extremely interesting and highly professional; I was very impressed. He did some outstanding real science and demonstrated a useful point that Al makes a great "host" for deuterium implanting.

Just an aside: since he proved he had heavily implanted deuterium in the aluminum target, and was hitting it with roughly 75 keV deuterons, then he was doing a good bit of fusion, too. Shouldn't he now be credited as a "neutron fusion" person and added to the neutron club? (of course, disregard if this has already been done.)

Also, I was wondering if the his device produces any significant X-ray radiation?

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Thu Oct 08, 2015 2:06 am
by Richard Hull
Robert is an old fusioneer and neutron club member of several years back.

Richard Hull

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Sat Oct 10, 2015 4:37 pm
by Sven Andersson
To Robert Tubbs:

I have an interest, both theoretically and practically, in the fusion reactions that tend to occur in various ion sources when they are fed deuterium gas. It would be very interesting to observe what happens, to the number of fusion reactions, in one of your ion sources, if you vary the pressure and extraction voltage and perhaps other parameters. If you're interested in discussing this contact me! pairwise.relations (at) hotmail.com

Best regards,

Sven Andersson

Re: Tubbs Accelerator Talk: 2015 HEAS

Posted: Fri Oct 23, 2015 8:19 pm
by John Futter
Robert
A very good presentation
To answer some Questions asked
For those using VDG for terminal voltage generation it is better to use Transil diodes in reverse bias PKE1.6400A types are good for secondary electron suppression
You do not have to divide off the main chain as the secondaries will charge the secondary electrode to the breakdown of the transil string see previous posts from me on this
Below breakdown leakage current is femto amps.

Aluminium is not a good target material for D2 H2 as it does not stay resident ie it permeates out very quickly
hence commercial neutron generators use copper nickel or titanium targets, SS is good to.
After 10 ^19 deuterium atoms per sq cm the target will bubble and flake ie surface damage as evidenced in some of
Robert's pics
X-ray generation is entirely due to secondary electron return to the ion source. Contain the secondaries you have seriously reduced the x-ray production.