Neutron Club Application - Nathan Marshall

[Nathan Marshall]

Achieving nuclear fusion became a dream of mine back in 2013 when I was 13 years old. The idea of being able to fuse atoms, the fundamental building blocks of all that we can see, tantalized me. I began experimenting with high voltage and vacuum with the goal in mind of building a fusor. I had a lot of fun building phosphor screen cathode ray tubes using a vacuum filtration flask, a rectified oil burner ignition transformer, fluorescent light phosphor, and a JB DV-85n HVAC vacuum pump. I took my cathode ray tube to the Kansas State Science and Engineering Fair where I won the physics division for my age group.

I successfully made a demo fusor in a bell jar by the time I was a freshman in high school. This is where my fusor progress stalled out. My lack of experience in constructing anything intended for real fusion combined with the financial hurdles required for building a true fusor chamber halted my push for fusion for many years. As high school went on, I built Tesla coils, Geiger counters, low pressure glow tubes, collected/isolated elements, and did a lot of fun chemical syntheses.

I had to leave behind my precious basement electronics lab and garage chemistry lab when I left for college at Kansas State University. Between working towards a dual major in Physics and Chemistry, club activities, and an undergraduate research job, I didn't get to come home very often. But whenever I did find the time and money to work on the fusor, I snatched parts from eBay and tinkered around in my parents' basement just like old times.

As a result of the corona virus, I found myself living back at my parents' house working on online classes. I decided to make it my goal to finish the fusor. I have been documenting my results since late March 2020 on my Images du Jour thread: viewtopic.php?f=18&t=13340

Today I am claiming to have achieved nuclear fusion. My equipment details are as follows:
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Main Chamber :
-6" Conflat Chamber w/ two 2.75" Conflat arms and one 1.33" Conflat arm
-2.75" Conflat viewport, viewed remotely with an arducam and a Raspberry Pi

Vacuum system:
-Salvaged Edwards E2M2 as a roughing pump
-Edwards Diffstak 63 diffusion pump for high vacuum
-Throttling is achieved with the integrated butterfly valve on the Diffstak
-Cooling is achieved with a bucket of water, aquarium pump, and a Lytron heat exchanger
-Edwards APG-M pirani gauge for foreline pressure measurement
-MKS 127AA-000.1C baratron for main chamber pressure measurement

High voltage:
-Homemade 35kV max power supply: ZVS-driven large AC flyback w/ voltage tripler
-Voltage measurement through four 100 megohm MOX resistors
-Current measurement through a 10 ohm 20 watt wirewound resistor
-30kV 2.75" Conflat feedthrough

Deuterium and gas handling system:
-Deuterium generated with a PEM cell and stored in a syringe
-Flow restriction with a Swagelok SS-SS4-VH metering valve
-Swagelok SS-43GS4 as a main gas line shutoff valve
-Gas lines are all 1/4" copper tubing
-Gas line is attached to the fusor with a 1.33" Conflat to 1/4" Swagelok adapter

Radiation Detection:
-BTI BD-PND bubble dosimeter, 21 bubbles/mrem
-The bubble detector is held about 5 inches from the center of the grid with a ring stand
-Ludlum model 14C with 44-9 pancake probe for x-ray detection
-Arrow-Tech W138 dosimeter clipped on my lead apron to measure my x-ray exposure

The whole setup -

The dosimeter location -

dosimeter_location.png (243.5 KiB) Viewed 2777 times

The PEM cell -

PEM_cell.png (235.05 KiB) Viewed 2777 times

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Run 1:
The details of the run are as follows. I first pumped down the chamber with the diffusion pump to far below one micron. After allowing the chamber to sit under vacuum for about an hour, I began generating deuterium with the PEM cell. It took about 30 minutes to fill the 60mL syringe. I transferred the syringe to the hose barb input on the gas line, and began feeding in the gas. I stabilized the pressure at 17 microns after alternating between throttling the diffusion pump and adjusting the metering valve.The gas flow rate was around 2mL/min. I had trouble attaining stable operation, and the voltage and current varied between 20-30 kV and 1-7mA over about 15 minutes with many stops and starts. I was still getting the feel for the "sweet spot" of chamber pressure and input power with the deuterium. After this run, I noticed that one large bubble had appeared in the bubble detector! I was elated but knew that I needed more bubbles and a nice stable run to really claim fusion.

Dosimeter before run -

Dosimeter after run with one bubble -

Run 2:
I refilled the deuterium syringe and stabilized the pressure at 17 microns again. This time the gas flow rate was a bit higher, around 3-4mL per minute. I established a stable plasma for 12 minutes at 25-28kV and 2.5-3mA. After this run, ten more bubbles had appeared in the bubble detector which equates to a neutron output of 2.4 mrem/hr.

Current during run two, showing 2.5mA here -

current_during_run.png (316.52 KiB) Viewed 2777 times

Voltage during run two, showing 27kV here -

voltage_during_run.png (249.21 KiB) Viewed 2777 times

The fusion star during run two -

The dosimeter after run two -

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I would like to thank all of you for your knowledge, suggestions, and encouragement. I can't even begin to imagine how much time I've spent learning from old posts on this forum over the years. I couldn't have done fusion without this wonderful resource. Lastly, I'd like to thank my parents for their unending support of my scientific endeavors. I certainly wouldn't have been able to do this without their encouragement, their willingness to split the costs of the more expensive components of the fusor with me, and their ability to listen to me ramble on about my work at the dinner table.

- Nathan Marshall

[John Futter]

Excellent Report Nathan
I'm sure Richard will annoint you shortly

[Rich Feldman]

Looks good to me, Nathan. I applaud your inclusion of a selfie picture, which used to be one of the requirements for neutron club admission. Shame if they let people in these days without one.

[Richard Hull]

Great work and a good job of it Nathan. I have added your name to the Neutron club.
For younger amateurs, understanding and supportive parenting is very important in any endeavor. Such efforts on the parents behalf are to be lauded.
To find a rare union of a youth with verve and the will to do, coupled with appreciative and supportive parents is quite rare.

Richard Hull

[Jim Kovalchick]

Congrats Nathan. You are a worthy club member!

[Dennis P Brown]

Nathan, congratulations and welcome to the neutron club!

Your work and especially efforts prove you are both a serious and excellent experimenter. You not only made your own deterium gas but your own (and impressive!) fusor power supply.

You also helped many future fusor people with your power supply work, alone.

You will, no doubt, insipire many other future people here and this will prove that with enough ingenuity, obstacles can be overcome using readily available equipment.

In that regard, you got me now collecting building supplies to begin construction of my new facility to setup all my old fusor (and other research equipment related to my thesis) equipment. Sore or not, I need to build that facility - not sure if that is a good thing considering all the other house projects still pending

Thanks for your posts and interesting work.

[Mark Rowley]

Congrats Nathan! Job well done and welcome to the club. Your report and presentation was nothing short of outstanding.

Looking forward to your future Fusor experiments.

Mark Rowley

[Nathan Marshall]

Thank you everyone for the abundance of congratulations and kind words! I deeply appreciate everything that everyone has said. I hope that I have the opportunity to meet any of you in person someday. I am glad we live in this internet age where it is incredibly easy to interact with like-minded folks, and where it is simple to access information to pursue our interests. This site exemplifies what I feel the internet should be used for... unfortunately that ideal model doesn't seem to occur very often.

On that note Richard, thank you for all that you have done and continue to due in maintaining and moderating this resource. And you're right: I'm very lucky to have parents that are endlessly supportive of my interests even though they personally aren't too interested in physics/engineering. I told them what you said about them and they wanted me to extend their thanks to you as well.