The next Kovalchick Fusor

Current images of fusor efforts, components, etc. Try to continuously update from your name, a current photo using edit function. Title post with your name once only. Change image and text as needed. See first posting for details.
Post Reply
User avatar
Jim Kovalchick
Posts: 717
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

The next Kovalchick Fusor

Post by Jim Kovalchick »

Mike and I made some decisions this summer about his original mixing bowl fusor. It served him well with learning about the basics of fusor construction and operations along with improving his skills with vacuum, high voltage, and nuclear instrumentation. Even though we have with time added some additional hardware features, the steel bell jar design was flawed in that leakage of the main seal was a given, and temperature caused fluxuations that often made control difficult. Mike has wanted to do activationn experiments for some time, and realistically his fusor just can't cut it. The decision to move on from the original fusor has been made. Mike's going back to school soon and really won't be able to participate in a construction project anytime soon. So, this one's mine, and maybe this is an opportunity for me to make my own bid for neutron club entry. So today, I am officially scounging for my fusor. I expect to start with some parts from Mike's like the roughing pump, turbo, vacuum instrumentation, and x-ray transformer power suppy. What's left is what should make this fusor better than the last, the chamber. We are shooting for essentially orders of magnitude less leakage and outgassing. That means no exposed jar seal, minimal grease, and more conflat. Last week, a good friend started me off with a great beginning contribution by donating a 6" tee. I have attached a picture to get my thread started. My goal is neutrons by the time Mike gets home for Christmas break. I am tempering my expectations though because we have the last of our uprate related outages coming at work soon and probably a job reassignment after that. So, if my project lingers on, please forgive me. I still firmly believe that safety is best enhanced by two in the lab, and my wife has volunteered to be my partner in avoiding electrocution, x-ray exposure, and various other unnamed disasters. I really think that she just doesn't want me to burn down the house, but I'm sure I will enjoy her company while I fuse deuterium. Wish me luck.

Jim K
Attachments
image.jpg
User avatar
Nick Peskosky
Posts: 135
Joined: Wed Aug 08, 2012 9:02 pm
Real name: Nicholas Peskosky
Location: San Diego, CA

Re: The next Kovalchick Fusor

Post by Nick Peskosky »

Best of luck on assembling Kovalchick 2.0, I look forward to seeing the route you go with you 6" cross. I try as best as possible to follow the same "two is better than one" mantra while operating my Fusor, usually that honor falls on my roommate or an observant friend. You can never be too safe around high-voltage, especially given that most of our devices are not engineered for industry standard interlocks and are experimental in nature.
Nick Peskosky
NPeskosky@gmail.com

"The whole of science is nothing more than the refinement of everyday thinking." - Albert Einstein
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: The next Kovalchick Fusor

Post by Richard Hull »

Looks like you are off to the races Jim! We know you will make fusion in your planned upgraded system. What you have there is what is needed to reach the more or less minimum easy activation level of 300k n/s. With a good HV supply of 36-45 kilovolts the mega n/s and abysmally easy activation can be had. All the best. See you and your lab and life partner in October.

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

Re: The next Kovalchick Fusor

Post by Jim Kovalchick »

I finished bolting up my fusor today. The next step is to mount it on its stand. It will be soon ready for vacuum draw down.

In the attached image, from left to right: NW-40 port for high voltage feedthrough; next is the main fusion chamber with a full size window equipped with sacrificial second pyrex disk inside; to the right are tees for vacuum instrumentation including a connection point for a baratron and ion gauge. The final NW-40 port connects to a bellows valve preceeding a turbo pump. Not seen in the picture but behind the high voltage feed through port is the gas inlet tap.
Attachments
image.jpg
User avatar
Jim Kovalchick
Posts: 717
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

Re: The next Kovalchick Fusor

Post by Jim Kovalchick »

I decided to perform my first draw down using my turbo equipped leak detector. My new chamber pumped down to the bottom end of the detector's thermocouple gauge (1 e-03 mbar) in less than 12 minutes. A few puffs of helium revealed a couple of very tiny leaks on some plugs I installed temporarily on the gas inlet and vacuum gauge ports. These were both fixed to give undetectable leakage. Next step will be to finish the plumbing of the baratron, ion gauge, and gas inlet. I am very pleased with the results so far.
Attachments
image.jpg
User avatar
Jim Kovalchick
Posts: 717
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

Re: The next Kovalchick Fusor

Post by Jim Kovalchick »

Next step completed. I disconnected the leak detector and installed the baratron and ion gauge. For this draw down I used the roughing pump and turbo in the normal operating configuration. The roughing pump brought the chamber to 12 microns and still dropping in 14 minutes at which point I started the turbo. After an hour the chamber was at 1.17 e-6 torr. I'm not totally happy with not making e-7 fairly quick, but maybe it's okay for a chamber that hasn't been heated. I isolated the chamber, and the first four minutes the pressure had only risen to 0.6 microns. I think this chamber is going to be more than satisfactory for fusion.

Next steps - build and install the grid
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: The next Kovalchick Fusor

Post by Richard Hull »

Jim, you have a huge leg up on this effort as you and Mike assembled that first fusor together and successfully operated it in spite of the kludge nature of the original chamber. The key to any fusor effort is learning how to get the finished product fusing, whether it be crude or 100% professional in manufacture. You are past that now.

This new effort should be much easier to get working and should certainly reach higher levels of operational performance.

My fusor IV is fairly well done, but has had a systemic leak since 2004 which I refuse to address as I can hit the 1 mega n/s mark, as you have observed in past years at HEAS. Only long term operational experience can do this in such a leaky system which, by vacuum head, scientific vacuum standards, is an abomination, yet good enough to do nuclear fusion.

Check out my current posting on preparing the fusor IV for presentation in two weeks at HEAS in the operation forum. I hit the 750,000 n/s mark last night with ease within 30 minutes of turning on the fore pump!

I will heap my best of luck on top of all the other well wishers. See you in 12 days.

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

Re: The next Kovalchick Fusor

Post by Jim Kovalchick »

Richard, Thanks for your observations on our past and present efforts.

You have had your mystery leak for quite some time and have obviously worked nicely around it. In the case of Mike's now dismantled mixing bowl fusor, its inherent leakage itself was not a bother because it was was within the capacity of the pumps. A bigger problem was the transient nature of the issue. His steel bell jar relied on a long circumference viton gasket with a little grease, the inner portion of which was exposed to the plasma. Startup plasma flashing was always an adventure in current management because we believe the initial plasma flash would cause a burst of viton outgassing and maybe even a temperature induced change in leak rate. Over time the gasket would temper, but the surface glazing also meant there was fine cracks that added to system leakage. Flushing the system with lots of D flow was required to get good neutron numbers and it also gave away fine control of the exhaust valve. I believe I am kissing all that good bye with cf flanges.

I have some decisions to make about the shape and size of the grid as well as its position within the tee. My feedthrough stem when installed just comes out of its chamber trunk into the intersection of the tee. This means that if I mount the grid at the end of the stem as it is, a traditional spherical grid will not be symmetrical with respect to spacing from the grounded chamber walls. One option would be to cut the stem back to center the grid within the trunk. There are couple reasons why I don't want to do that including making it harder to see it from my view port. Right now I am leaning toward shaping the grid like an egg with its fatter end opening into the tee intersection. Pictures and results to follow.
User avatar
Richard Hull
Moderator
Posts: 14992
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: The next Kovalchick Fusor

Post by Richard Hull »

I really don't think that the grid shape or positioning will matter much in the final analysis. I would keep it more or less spherical. (I never care about a little eccentricity)

I would also try and put the grid wherever it is best viewed from. This is normally close to the center of the device.

In a 6 inch Tee, I would think I would use a 2 inch diameter grid, regardless of whether a sphere, elipsoid, or cylinder.

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
Post Reply

Return to “Images du Jour”