Fusor Forums

The following post depicts MATER-1: Massive Amateur Test Electrostatic Reactor Version 1.

This fusor was constructed over the past year by myself, Timothy Koeth, Jay Howson, and Jimbo Krutzler.

All of the equipment seen in this project was acquired through surplus sources.

System:

Vacuum: The vacuum system consists of a 2-foot diameter, spherical chamber with 26 ports. The chamber is roughed with two mechanical pumps; one large Edwards mechanical pump to bring the chamber down to 4 mTorr, and a second which backs a 50 l/s turbo pump. The base pressure of the chamber is 5e-7 Torr.

High Voltage: The high voltage system consists of a Glassman -80kV 38 mA supply. We also have a -150 kV 2 mA supply which will be used, but does not provide as much current for a high neutron output.

Neutron Detection: Our neutron detection consists of four 3He detectors: A Texlium "Special" 22" detector, a Reuter Stokes RS-P4-0820-103 22" detector, an LND 2520 8" detector and an 8" Reuter Stokes probe. As of right now we have the two larger detectors setup with full NIM instrumentation but are working through issues with electrical noise. In addition, we are using activation and a sensitive HPGe to confirm our neutron production.

Gas supply: The gas system consists of a deuterium lecture bottle as well as a needle/shut off valve. This provides sufficient gas control to maintain the same pressure for hours.

Shielding: Our shielding consists of a >1" Leaded glass panel


Our hope is to use this machine as a platform to run others' experiments and test ideas. Please feel free to suggest different experiments.


First Run:

Our first neutron producing run was at 4 mTorr of deuterium and 55kV /7 mA on the high voltage power supply. This was suffecient to activate indium after a 10 minute exposure (note second to last picture). Also note the HPGe Spectrum in the last image.

We have much much more to come, so please stay tuned. We hope to calibrate our detectors and give a total isotropic emission rate.

You have a lot of resources.


You could try a beam on target with that high voltage low current supply.

This is an amazing fusor, and I felt privileged to participate in some of the first operations of it. It controls like a dream compared to my own especially after the alumina tube was removed from the stem just approaching the grid. Some improvements like a tungsten grid, a secondary ground grid, and an ion source would take this monster to incredible numbers, but I think it is already well into the 10^7 range.

The lead glass shield is more than a luxury. I took measurements with an ion chamber of the x-rays and without mentioning the numbers I got, suffice to say that you don't want to hang close to the beast.

The other thing about this device that amazed me is much more subtle and less flashy but nonetheless important. The leakage into the chamber is incredibly low. It will hang below a millitorr for a long time. This really economizes on d use. It is inspiring me to go back and look for leaks on my reactor again.

Congrats to Tim, Scott, Jay, and Jimbo. Your skill really shows. I am truly impressed.

Hi Jim
Please comment about removing the alumina tube from the stem of the grid.
Does it degrade the performance?
I was looking for an alumina tube in order to install it on my HV feedthrough...
Thanks in advance,
Roberto

Roberto,
Their stem has a relatively thick alumina tube insulating it between the insulator and the stainless grid connector. Originally they put a thin alumina tube on a stem piece after the connector and before the grid. This thin piece seemed to be too thin at high voltages and sparked a great deal limiting further voltage ascension. Removal of the piece and leaving it bare eliminated the problem. The exposed stem does experience some bombardment heating and because it was only stainless, it tends to get pretty hot. This latter factor is probably the most limiting piece for higher currents. They should rebuild with tungsten and/or greater thickness for the piece.

I know Carl W built his fusors with the entire stem bare. I personally don't see an issue with this as long as you can make sure you don't arc to the sides of the chamber if your conductor has to make it past any narrow area before the chamber opens up to the grid.

hope this helps.

Jim K

Jim

Very clear explanation.
Thanks,
Roberto

Would you four folks like to enter the neutron club as a team? Perhaps as a U of M team?

Great work!

Richard Hull

Excellent effort by all involved.

Congratulations on building such a fine system. Any university or professional lab would be challenged to match what you four have created. I’m looking forward to your upcoming experiments.

Bruce

Thank you all for your kind responses.

Richard, please feel free to enter the team into the Neutron Club. However, please do not list us as a University of Maryland team as the project has no affiliation with the university and is a completely separate/amateur effort.

I have made a short video which shows the plasma discharge inside of the fusor from ~500 mTorr to 5 mTorr. I hope this video acts as a helpful resource and can help people who are new to fusors understand how the plasma changes with pressure:

https://www.youtube.com/watch?v=Snu8Ivu9YIA

Scott Moroch

Scott, I will log this into the neutron club as a team effort without the UMd tag.

Your last two images are indicative of real fusion taking place. While not absolutely conclusive in and of itself, these images are the most characteristically observed fusion symbols in the visual sense.

Great work and a fine system!

Richard Hull