Fusor 2020

For posts specifically relating to fusor design, construction, and operation.
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

That’s definitely the plan however I think I’m destined to one last BTI purchase for the linear pinch project. Once I get this new Fusor stabilized I’ll be resuming the Columbus-1 project. I needed a change of pace before going full bore into the pre-ionization phase of the pinch tube. I’m hopeful to get enough pinch neutrons so I can go the activation route and abandon the BTI’s altogether. As we all know, BTI’s are an apoplexy inducing money pit.

But back to the Fusor2020, it’s current neutron output is more than enough for indium activation. After a few indium activations I’ll be proceeding to silver. Tim Koeth helped out with some premium silver foil so I’ll be transitioning to that fairly soon.

Mark Rowley.
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

Today’s run lasted a total of 10 minutes. Within that time span, I continued to make adjustments and on several occasions turned off the power supply so I could safely adjust the diff pump gate valve.

The top BTI dosimeter reflects the total 10 minute run at 45 bubbles.

The bottom dosimeter reflects a 3 minute timed count when I got the cpm to somewhat stabilize around 6kcpm (45mTorr D2 / 45kV / 3mA). During the count, the Fusor fluctuated twice and each time dropped to about 5500cpm. Total of 19 bubbles. Both dosimeters were at approx 17cm from the central grid.

Unfortunately, this is the second of only 2 runs where I’m once again going to have partially open the chamber, thus ruining any conditioning it had. Looks like I may have overtightened the viewport causing some damage to the Viton o-ring. Not a big deal, but slightly annoying.

Mark Rowley
F7BCFEAC-3B5F-4117-AA16-45629BC42149.jpeg

C5C80442-17AD-41C2-8C62-9397ED56D812.jpeg
Tony Lai
Posts: 15
Joined: Mon Aug 10, 2020 8:05 pm
Real name: Tony Lai

Re: Fusor 2020

Post by Tony Lai »

Wow.... Would you mind me ask what is the inner diameter of your chamber? Planning to make one with smaller size just like Jon's cube, but just wondering if chamber size affacts fission efficiency.
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

2.3” inner diameter.

I’m not sure what Jon’s cube is bored out at.

Fwiw, this 2.3” size is a phenomenally better system in all regards than the smaller cross fusor. Very stable operation which allows the operator to establish a desired neutron flux rate and walk away while it activates target material. The cross required constant fiddling with the voltage and deuterium flow rate to keep the numbers up.

Mark Rowley.
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

Cooling has become a pivotal issue. I’ve tried various methods of forced air including refrigerated forced air. All have worked to some degree with the refrigerated arrangement being the best. Unfortunately the latter system only works a few minutes longer than regular forced air which results in a fail for long term activation experiments.

Recently Jon Rosenthiel shared a spectacular approach to water cooling with his cube fusor. On one side of the cube, he milled in a water maze where he pumps coolant through during high output runs. After a 900 watt 20 minute run, the cube hit a peak of only 41 degrees C (105F)!

Here’s Jon’s very detailed post:
viewtopic.php?t=13579

Such a result is presently beyond compare and also extremely clean. No soldered on copper tubing which only has very limited surface contact for thermal exchange.

As of now, I’m about 50% complete with a similar modification to Fusor2020. I will be incorporating two watermaze arrangements (one on each side).

The mazes are complete. All that needs to be done now are the 3/8” caps and related aluminum NPT fittings.

Mark Rowley

38EBCC5E-E5AE-4F4C-948F-0228AB461EFE.jpeg
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Fusor 2020

Post by Richard Hull »

I have actually mused over a totally submerged fusor with a cold water tank circulating system. 100% coolant contact. It is definitely doable although a bit bulky and heavy for all but the smallest systems. Gotta' keep musing and thinking. A spherical system would look like a sea mine with only the hv insulator and vew port poking out of the water. A nice cylinder fusor would have only the HV terminal out of water. The view port would be viewable under water via a clear tank or a separate nearby view port in an opaque metal or plastic tank. Such a system would require a larger view port of perhaps 3 or more inches. Great effort Mark!

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Fusor 2020

Post by Dennis P Brown »

While I used flexible copper tubing to wrap my fusor body (and conductive epoxy to hold it in critical places) and ran water, one isn't required to use water. Standard available propane could be used - it has an even greater heat capacity then water(!) and better still, it is non-conductive. Yes, leaks create an explosive hazard and only someone really capable of creating leak proof plumbing should consider such a system. But it is used in many modern cooling devices (std. AC units), is cheap, non-toxic, and using an old refrig. compressor can be easily assembled (I did this in college to achieve minus -40 C for a diffusion pump cold trap.)
Jon Rosenstiel
Posts: 1494
Joined: Thu Jun 28, 2001 1:30 am
Real name: Jon Rosenstiel
Location: Southern California

Re: Fusor 2020

Post by Jon Rosenstiel »

Looks really good Mark, I’m impressed.

JonR
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

Cooling maze modification completed. Today’s test made sure there were no leaks by pumping chilled coolant through the system for a couple hours.

The cooling lines coming from the rear maze will require a slight modification to the HDPE moderator and X-ray shield. With any luck I should be able to initiate a fusion run in the next day or two.

Mark Rowley

616D437E-7783-4B5C-A3CE-51263EE65972.jpeg
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Fusor 2020

Post by Richard Hull »

Fabulous effort and no leaks...Great! Ain't it a bear how one, when upgrading, has to change other stuff that was fine until the "new thing" forced alteration of, or cutting, or boring some wonderful thing that was crafted earlier. Add-on stuff always seems to get in the way of what was "finished goods". In the end, during research and improvement, nothing is finished goods. Very little is ever finalized. We keep on searching for improvements in all areas.

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

First run with the cooling maze was a resounding success. Following a 15 minute sustained run at a roughly estimated neutron TIER of 1.3E+6 it never peaked over 87F (30.5C). Cooling fluid was water with Rislone Hy-per Cool Super Coolant. As of now, the coolant is only recirculating within a 2 gallon reservoir with no radiators or extra cooling system. Adding a couple fan cooled computer-type radiators (as in Jon’s system) is something I’ll probably employ in the future.

In addition to these changes I opted to replace the Yellowjacket HVAC pump with a much quieter and more efficient Welch DuoSeal 1402. Being a higher capacity pump, it’ll rough down to almost 9mTorr in a couple minutes. The Yellowjacket could rough the system down to around 12-13 after about 5-10 minutes. Performance wise with the fusor it’s negligible but at least the lab is a once again a quiet place during operation.

One other bit of good news is the fact that I was able to keep the HDPE moderator in the exact configuration and distance as it was when BTI calibrated a month or so back. I’ll double check calibration in the next few days to see if the water in the two mazes have made any significant differences with moderation.

Mark Rowley

2A89E1B1-2ED2-4528-A3AA-9242B9811DFD.jpeg
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Fusor 2020

Post by Richard Hull »

Great report and I am glad you are running cool. I used a yellow Jacket from 1997-2003. It could hit 8 micros on fusor II , but with the increased volume in fusor III, it hit 10 or12 microns in a few minutes. Ultimately, like you, I swore off direct drives and went for the much more soothing lup-lup lup of a belt drive, slow winder. Great work.

The key is that, once calibrated, never move the moderator or significantly alter the positions of any major physical object around or near the moderator. Fusor IV was frozen in space 2004-2019. Right now, as I am un-calibrated I have complete freedom to just mess the entire system up and introduce or remove anything as it pleases me. I really do like this, as I can experiment and allow the 3He tell me whether I have made a quantitative improvement. With the silver activator buried in the moderator, I can always prove I am doing fusion over and above any questions regarding the 3He counter which we all know is showing fusion is taking place. Still.......Dead silver made radioactive in a few minutes always shuts up any doubters related to electronic neutron counting instrumentation. (Not that anyone has doubted the 3He heralding fusion.)

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

A very good point Richard. Totally plays into why I’m having so much fun with activation lately.

After a second test run this afternoon I noticed an annoying backscatter problem. Easily fixable but moderator configuration will undoubtedly get altered. If the aging BTI’s fail beforehand, I’ll be just as happy with activation numbers and gamma spec.

Mark Rowley
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

Before resuming the BoT2021 project, I’ve decided to try something unique with this fusor.

Reviewing old disassembly photos from last year, I came across the beam impact “lozenge” images from the inside wall.

C35FB9A7-E9FD-47D9-9312-962B930B88EF.jpeg

The lozenges expectedly line up with each of the 6 “star mode” beam radials from the grid.

Since I’m making some deuterated titanium targets for the BoT2021 project, I figure I’ll try installing several in the fusor before it’s temporarily disassembled. Placement will be on the chamber wall in the same location as the lozenge impact marks where they will serve as deuterated targets.

If the ion beams have any type of BoT characteristics as indicated by fusors with cylindrical grids, this might result with a substantial increase in neutron production… or it just may fail miserably.

Either way, I’ll update with the results soon. And of course this is all incumbent on the success of the deuterizing apparatus.

viewtopic.php?t=14055

Mark Rowley
User avatar
Jim Kovalchick
Posts: 717
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

Re: Fusor 2020

Post by Jim Kovalchick »

Mark,
I recommend using small Ti targets. I used large pieces of it in mine and found pressure control became difficult. I was also using a ring grid then, so perhaps your multi beam arrangement may help avoid big temperature induced pressure changes.

Jim K
User avatar
Richard Hull
Moderator
Posts: 14991
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Fusor 2020

Post by Richard Hull »

"Let the experiment be done" Benjamin Franklin

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
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
User avatar
Mark Rowley
Posts: 909
Joined: Sun Dec 29, 2002 12:20 am
Real name: Mark Rowley
Location: Sacramento California
Contact:

Re: Fusor 2020

Post by Mark Rowley »

Jim, definitely going small. The furnace will only host a maximum size of 15x40mm. I’ll be using 0.203mm sheet and each target will probably be 15mm sq, possibly smaller. Installation will utilize a simple slide-in low profile aluminum sleeve (or similar).

First run will probably utilize a single target. If it works, one would be sufficient to identify any positive results.

Mark Rowley
User avatar
Tonya Fisher
Posts: 3
Joined: Wed Aug 25, 2021 4:49 pm
Real name: Tonya Fisher

Re: Fusor 2020

Post by Tonya Fisher »

Hello, I'm thinking about making fusor at home like a student project, so could you help me a littleฅ^•ﻌ•^ฅ Could you tell what hight-voltage environment you used and send a paper plan of the fuser. And how do you regularl gas pressure? Sorry for stupid questions (they can be for professional) and my English (it's yep not the second my language). Best wishes, Tonya
User avatar
Dennis P Brown
Posts: 3159
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Fusor 2020

Post by Dennis P Brown »

Tonya, you did an intro and have followed all the rules. But its best to create your own thread to ask such a question and not use someone else's topic thread for that purpose. Also, read the FAQ's before asking questions since most answers are to be found there.
User avatar
Tonya Fisher
Posts: 3
Joined: Wed Aug 25, 2021 4:49 pm
Real name: Tonya Fisher

Re: Fusor 2020

Post by Tonya Fisher »

Oh, I did that before reading FAQ. I m sorry I haven't read the rules that time. So, now I have basic information about fusors. Thank you
Post Reply

Return to “Fusor Construction & Operation (& FAQs)”