Alexey's fusor progress

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.
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Alexey's fusor progress

Post by Alexey Khrushchev »

Hello everyone
I want to open a new topic, because I have already accumulated some parts of my future fusor and I would like to discuss them with specialists. Today I have almost assembled my high-voltage power supply, which is based on a Chinese 60 kV, 600 W precipitator. The scheme is presented below. The voltage divider was fixed on a piece of acrylic glass. I drilled several holes in the bottom for better oil circulation, I think this will allow the ballast resistor to be cooled more efficiently. I want to immerse the board and resistors in a box with transformer oil. Voltage regulation will be carried out using a glass rod, which I connected to a variable resistor on the board using a coupling. Please see if I did everything right, and after pouring the oil, it will be very difficult to redo anything.
Attachments
HV.jpg
HV2.jpg
IMG_20231105_171518.jpg
IMG_20231106_172442.jpg
IMG_20231106_172526.jpg
IMG_20231106_172743.jpg
User avatar
Richard Hull
Moderator
Posts: 14950
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Alexey's fusor progress

Post by Richard Hull »

Your assembly looks interesting. The power supply for a fusor is one of the more critical components and among the most difficult to bring to bear successfully.

I have no personal experience with switcher systems, especially the Chinese one that you are attempting to use. Switchers are custom designed for one thing, as a rule. Repurposing them for another application can be tricky, especially when high voltage output is involved and currents within their watt rating is concerned.

Several people here at fusor.net have already dealt with these same Chinese supplies. I will defer to them on advising you beyond my admonitions above. I do hope you will receive advice from those here who are more competent in this matter, and wish you well in testing and using this supply setup you have given images of and your reasoning as to how you have prepared it for use.

I assume you have seen some of the efforts here by others. Please be aware that a number of people are here for the "win" of doing fusion. Once done, a significant fraction of those may disappear from these forums, moving on with their lives. As such, those who mastered the issue of the Chinese supply adaptation may no longer check into the forums here.

I hope someone sees this who can talk with you about their efforts from a point of actual hands-on experience.

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
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

It is a pity that some talented fusor builders are abandoning their projects. It seems to me that there are many interesting experiments that can be tested on an amateur fusor. For example, when I build my fusor, I want to test the effect of deuterium pre-ionization with Am-241. I will simply place the source from HIS-07 directly into the chamber (at the deuterium inlet, far from the electrode) and check how this will affect the lower pressure at which plasma is still beginning to form. Perhaps this will allow you to raise the voltage without the danger of arcing and thereby increase the efficiency of the reaction.
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

I have seen many people install a ball or torus on the end of a high voltage electrode. I think this is a good solution to prevent localized charge buildup on the bolt tip. It is not very clear to me what to do with the sharp parts of the high voltage cable terminal. Ideally the terminal should be inside a hollow ball, then the charge will be evenly distributed on its surface. But this is difficult to realize. What happens if the terminal is placed under the ball as shown in the figure? And what diameter of the ball should be used?
Attachments
Ball.jpg
Matt_Gibson
Posts: 494
Joined: Thu Sep 23, 2021 10:36 am
Real name: Matt Gibson

Re: Alexey's fusor progress

Post by Matt_Gibson »

A few of us use small toroids on the top electrode of the hv feed through. I use one of those “30kV” feedthroughs with one and push 65-70kV.

As for abandoning projects, I just got busy with others. Still have the fusor ready to go if a neat idea comes along or I think up an idea to help push my voltage even higher.

-Matt
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

A little bit about how I made a high-voltage feedthrough electrode. As a base for the electrode, I took a 15 mm diameter, 400 mm long mullite-silica tube with a 5 mm channel in the center. I drilled a hole in the KF50 plug and inserted the tube into it. To seal it, I welded the tube to the plug using pure indium. To do this I had to treat it with silver nitrate and calcine it at about 400C. The indium wetted the tube well, but the contact with the steel of the plug was not good and after some time it simply fell off. I should have coated the steel with copper, then this problem would not have happened. So I had to seal the outside of the tube (air side) with JB weld. The tube turned out to be porous and would leak air when pumped out, so I greased it with vacuum grease, then put on the 3D printed tube and filled it with epoxy. I used 1mm diameter tungsten wire as the center mesh material. I made two "horseshoes with legs" with a diameter of 10mm. To prevent the wire from breaking I heated it in the flame of a torch, but in this case I succeeded only on the 10th attempt... Inside the electrode I inserted a stud with a thread m4, on its end I put a steel tube in which I inserted the "legs" of the tungsten grid. Running at voltage up to 4 kV and current up to 20 mA showed that the grid works well, and the electrode is sealed. When I assemble the high voltage source, I will test at operating voltages, but so far I'm happy with everything. The electrode turned out to be very long - about 40 cm, but I did not shorten it for two reasons: firstly, this length excludes external breakdown of the arc on the chamber. Secondly, the longer the electrode, the less heat will reach its upper part, where the metal is in contact with the epoxy.
Attachments
5.jpg
4.jpg
3.jpg
2.jpg
1.jpg
User avatar
Richard Hull
Moderator
Posts: 14950
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Alexey's fusor progress

Post by Richard Hull »

A fabulous, though tortured, piece of work on that insulator! This vacuum to air HV connection is always an issue in making a fusor.

I hope this holds as you increase the voltage. Homemade arrangements sometimes defy reason and logic when brought into service. All the best of luck. We are looking to your future reports on your efforts.

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
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

In case something goes wrong with this electrode, I have a plan "B". I have a pair of KF25 compression adapters for the 14mm tube. The lower adapter connects the glass tube to the chamber, and the upper adapter creates a sealed connection and has a high voltage cable connected to it for voltage. It is clear that inside the tube there is a metal rod connecting the cathode and the upper adapter. On the forum someone experienced people did something like this and it worked well, can't find where it is now.
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

For my birthday, my wife gave me a bottle of heavy water as a gift. It is probably the most unusual gift I have ever been given). My son made a fusion reactor for me in Minecraft. I wonder how your friends and relatives feel about your unusual hobby?
Attachments
D2Os.jpg
User avatar
Richard Hull
Moderator
Posts: 14950
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Alexey's fusor progress

Post by Richard Hull »

There are many hobbies that are bizarre by the standards of most people. Amateur science and related technologies are really rather common. However, this attempt to do fusion is relatively new by any standard. Thus, it seems a bit weird to the common person as they can't see a reason to invest money and time into doing fusion with no demonstrable energy or useful product once it is done by the amateur.

I find this reaction odd, as many hobbies produce nothing of great value beyond the satisfaction of enjoying the effort. The positive part is that you learn to do things you have never done before as part of a growing skill set and expanding knowledge.

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
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

I've been thinking about a problem for a while. My fusor is in an unheated workshop in a country house. The temperature in the room drops below -10 C in winter. When I turn on the heating, the workshop quickly warms up to room temperature, but condensation forms on cold surfaces. It is particularly unpleasant that condensation forms on the box containing 5 litres of oil in which the precipitator is located. If water gets into the oil, it will be a big problem. It might be worth warming the oil to prevent condensation. I have a 2.4kOhm/10W resistor, if I dip it in oil and connect it to 220V it will draw 20W, which is twice the rated value, but as it will be in the oil I think it will be fine. Of course I will use a 0.5A fuse and also monitor the oil temperature with a thermocouple.
Alexander Ziemecki
Posts: 58
Joined: Mon Aug 21, 2023 6:25 pm
Real name: Alexander Ziemecki

Re: Alexey's fusor progress

Post by Alexander Ziemecki »

Hey Alexey, what exactly are your safety plans for the Am-241? Transport, Storage, Handling, etc? I am sure your plans are very safe. I only bring it up because the first thing I think of, when americium is mentioned in this context, is what happened to David Hahn, the Nuclear Boy Scout. Despite his clear brilliance and scientific skill, his life ended very quickly and very sadly due to his handling of americium from smoke detectors for an at-home reactor/neutron source.
https://en.wikipedia.org/wiki/David_Hahn


Again, I'm sure your safety plans are sufficient. I'm just curious what they are.

Удачи )
Саша
Matt_Gibson
Posts: 494
Joined: Thu Sep 23, 2021 10:36 am
Real name: Matt Gibson

Re: Alexey's fusor progress

Post by Matt_Gibson »

The David Hahn story is wayyy overblown.
Alexander Ziemecki
Posts: 58
Joined: Mon Aug 21, 2023 6:25 pm
Real name: Alexander Ziemecki

Re: Alexey's fusor progress

Post by Alexander Ziemecki »

Maybe, but it's still your problem if the wrong person catches wind, because the public doesn't know and doesn't care.

David Hahn couldn't give a good enough explanation to the cops, and because of that, the FBI got involved, and his backyard was designated an EPA Superfund site.

All I'm saying is, practically, maybe it's a good idea to have a paper labeled "Containment Plan" somewhere on your person while doing this. Just in case.

Again, not doubting that you have a safe plan, just curious what it is. It is a very interesting experiment, and I'm interested in reading the results.
User avatar
Dennis P Brown
Posts: 3118
Joined: Sun May 20, 2012 10:46 am
Real name: Dennis Brown

Re: Alexey's fusor progress

Post by Dennis P Brown »

I agree with Alex's points. Safety is critically important. X-rays from the fusor is the big one that needs attention. Safety with the lethal voltages is paramount.

Considering the cost of a power supply, deuterium gas and the steel chamber, a HV feed-thru isn't a terrible cost. What is terrible is if a home-made HV feed-thru leaks. It is difficult to detect such a leak and really can ruin a fusor's performance in many ways.

Unless you are working with voltages well about 25kV, the issue of corona discharges on the HV feed isn't a serious issue if you avoid sharp points and corners. For instance, I cap my HV terminal screw point with a small copper sphere that is just half an inch large. Through, for 32 kV, this really is over kill. I use a file to round the sharp edge of washers or use plastic ones. I could also file/round the threaded screw part of the HV feed (where I connect the HV cable) instead of the copper sphere but it was easier since I had the small copper sphere. I drilled and tapped it myself.

Placing HV components under oil is an easy and good way, as well. Looks like you are doing that or planning to do that.
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

Alexander, I haven't started designing the Am-241 experiment yet. The danger is to atomise the source with plasma, then the dust will be released into the atmosphere via a mechanical pump. So I will be very careful about all safety measures and if I can't provide them, I'd better give up this experiment.

Dennis, thanks for the comments about the HV feed-thru. I have already attached a 50mm diameter hollow steel ball to my HV feed-thru, just drilled a hole in it and screwed on an M5 bolt on the end of the HV feed-thru. Following your advice I will trim the sharp edges on the HV wire terminal.

I am currently busy making a neutron shield. It will be based on 3kg of boric acid, paraffin and lead. I will write a detailed report on it later. I am also thinking of a system for obtaining, drying and storing deuterium.
User avatar
Richard Hull
Moderator
Posts: 14950
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Alexey's fusor progress

Post by Richard Hull »

I do not know of many people with a neutron shield. At one time we talked about them but so few neutrons are emitted by the average amateur and more or less isotropically that at a 2 meter distance between the reactor and the operator is usually sufficient. It is not likely that you will spend many hours operating the fusor at max power. Thus, distance and limited time of exposure to the fusor in peak operational mode pretty much obviates the need for a neutron shield.

The key possibly significant radiation to shield for is x-radiation! This is the big danger once you exceed 35 kv on the fusor. Viewports go dangerous after 20kv. So much of this information is noted in the radiation FAQs forum. I have operated since 2004 over 44kv @12ma with no neutron shielding at all. I do have operator lead shielding in place such that during an operator worn 100mr dosimeter reads zero mrem absorbed dose on my chest after a 2 hour run session with about 20 minutes of that time at full power. I operate a classic 6" SS spherical chamber. I remain one of the very few operating the old spherical chambers.

The big danger in and around a running fusor at full voltage and current are electrocution and X-radiation.

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
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

The fusor.eu website presents a calculation of the absorbed neutron radiation dose during operation of a standard fusor (1E+6 neutrons/sec). According to their calculations this is a dangerously high radiation level in the immediate vicinity of the chamber (15.8 µSv/h.). At a distance of more than 2m the operator receives a relatively safe dose according to the approved standard for a nuclear power plant worker. It is clear that the fusor never runs for hours and most likely the operator will not receive a dangerous dose, but it is emotionally difficult for me to be near such a radiation source. You could say that I am making a neutron shield for my own peace of mind, well that's interesting enough. As a basis I have chosen the scheme described in FAQs on this forum with some additions. It is a 50x50cm plywood box with layers of shielding components. The closest layer to the fusor is a 5cm thick paraffin plate (neutron moderator), then there are two layers of polypropylene water pipes (d=20mm) filled with 3kg of boric acid (moderator and neutron absorber), the third layer is a 3mm thick lead sheet (absorption of X-rays and gamma radiation arising from the absorption of thermal neutron by boron). The difference from the classical scheme is in the use of tubes, which are a convenient container for boric acid, as well as in the location of the lead layer after the boric acid layer.
Attachments
shield.jpg
User avatar
Richard Hull
Moderator
Posts: 14950
Joined: Fri Jun 15, 2001 9:44 am
Real name: Richard Hull

Re: Alexey's fusor progress

Post by Richard Hull »

Certainly this would be the most impressive catch all radiation shield ever fabricated in these forums. I can respect peace of mind shielding as it is a personal decision.

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: 713
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

Re: Alexey's fusor progress

Post by Jim Kovalchick »

I'm sorry, but I have to disagree with the statement about 15.8 µSv/h being dangerous. The NRC does not even require posting that rate at its lowest level, Radiation Area. Even with a full quality factor of 10, it is below the 2 mRem/hr limit.
User avatar
Jim Kovalchick
Posts: 713
Joined: Wed Apr 13, 2011 8:00 pm
Real name:

Re: Alexey's fusor progress

Post by Jim Kovalchick »

Upon my review of the fusor.eu method, I believe the entire discussion about dose needs to be revisted. The number you obtained from fusor.eu is not what you want. That number couldn't be more wrong. It assumes that 50% of the neutrons are born from tritium fusion and come out at 14 MeV. That is too far from the truth to be taken seriously. Also the number presented has nothing to do with a million neutrons per second. To understand neutron dose, I recommend an alternate approach.

Better to look at Table 1004(b).2 of the US code of federal regulations 10 section 20.1004. Firstly ALL of the neutrons can be assumed to be born from DD fusion. Unlike the ridiculous assumption made by fusor.eu, the amount of tritium related fusions will be too small to measure. This means you look at the table for the quality factor for 2.45 MeV neutrons. From the table, a total fluence of 2.5 MeV neutrons distributed evenly over an adult body will add up to a REM if there are 29 million neutrons per cm^2.

A million neutrons per second produces a distributed field of 88.4 neutrons per second per cm^2 at 30 cm. This means it will take about 328,000 seconds or 91 hours to get to a REM (29 million neutrons per cm^2). This means about 11 mRem/hr at 30 cm. You won't actually measure that high 30 cm from the fusor at 1 million neutrons per second because that is a single spot on the sphere of neutrons. The field diminishes significantly. Also, the dose number assumes a uniform field of neutrons on the body. So, the 11 mRem/hr number is very conservative.

At a million neutrons per second, I wouldn't recommend anyone spend all their time 30 cm from the fusor for multiple reasons. The x-rays will probably be high, and the high voltage risk is not small. The neutron field is not tiny, but it is not dangerous. Stepping back another couple 30 cm makes the dose rate negligible.

I do recommend lead shielding for x-rays, but the neutron shield isn't really necessary. As Richard says, it is your choice when it comes to your own comfort level. Good luck. I think your shielding efforts will be interesting.

Jim K
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

I am not an expert in the field of dosimetry and it is difficult for me to understand this issue. However, the presence of neutrons with energy 14.1 MeV seems to me quite probable. The tritium ion produced as a result of the D-D reaction will have a huge energy of about 1 MeV. The rate of D-T reaction at this kinetic energy is 2 orders of magnitude higher than D-D at 30 keV. Therefore it seems to me that all tritium ions will immediately interact with deuterons. Thus neutrons with energy of 14.1 MeV should be in considerable quantity. The higher the neutron energy, the more dangerous it is for the organism, so the authors on fusor.eu used weighting factors.
User avatar
Liam David
Posts: 502
Joined: Sat Jan 25, 2014 5:30 pm
Real name: Liam David
Location: Arizona

Re: Alexey's fusor progress

Post by Liam David »

On the order of 1e16 charge carriers impact the electrodes of a typical fusor in any given second. The total number of ions and electrons is much higher, but this figure represents an upper bound on efficiency for my following argument, so I'll run with it here. Let's say that this device produces 1e6 n/s, giving an "efficiency" of 1e-10. That equates to 1e6 tritium/s (T/s). These T atoms have an energy ~1 MeV, giving a D-T cross section ~10x higher than D-D at 30 keV. Thus, you might expect a D-T reaction rate to be 1e-10 x 10 x 1e6 = 1e-3. In other words, you might get a single D-T neutron for 1000 s of runtime. A billion D-D neutrons are emitted in the same time. Moreover, according to https://www.nrc.gov/reading-rm/doc-coll ... -1004.html, the dose per unit fluence for 14 MeV neutrons is only about 2x higher than that for 2.5 MeV neutrons. There is zero D-T risk in a D-D fusor. Unless you're hugging a 1e6 n/s fusor for hours on end, there is also essentially zero D-D neutron risk. Calculate the maximum possible neutron dose you would expect to receive given your output and distance (an exercise in dimensional analysis), and then compare it to the yearly background radiation a typical person receives. I would only grow concerned about potential neutron doses with D-D neutron rates >>1e7 n/s. A typical 30 kV fusor is 2 orders of magnitude below that.

X-rays, on the other hand, are a real danger, and a simple "shadow" shield is not enough due to reflections off metal surfaces. Small pinholes in shielding will also let copious x-ray flux through. Compare the ~100 mRem/hr neutron field at a fusor shell (at 1e6 n/s) to the >>10 rem/hr x-rays found at viewports. These are x-rays from bremsstrahlung, not prompt x-rays/gammas from neutron capture which pose no threat at 1e6 n/s.
Alexey Khrushchev
Posts: 83
Joined: Thu Jul 06, 2023 3:36 am
Real name: Alexey Khrushchev
Location: Moscow

Re: Alexey's fusor progress

Post by Alexey Khrushchev »

That's very interesting, thank you! I would like to clarify how you calculated the number of ions in the fusor? Is it based on current consumption? Or through residual pressure and chamber volume? It seems to me it is necessary to take into account geometrical factor - triton is born in the centre of the grid where the maximum density of deuterons is reached. The free path of ions there will be much lower than at the walls of the chamber.
User avatar
Liam David
Posts: 502
Joined: Sat Jan 25, 2014 5:30 pm
Real name: Liam David
Location: Arizona

Re: Alexey's fusor progress

Post by Liam David »

The number of beam-beam fusions in a glow discharge fusor is on the order of 1e-6 the beam-gas and beam-target fusions, so I estimated the D-T reaction rate assuming that the triton interacts only with the background neutral gas. This is primarily because glow discharge fusors create weakly ionized plasmas and so the ion density is much lower than the neutral density. I'm estimating the ion density from measurements performed by various groups, simulations by myself and others, and back-of-the-envelope calculations. My 1e16 charges/second is just from 0.01A / e for a typical fusor. Of course, in principle, the flux of charge carriers doesn't tell you anything about their densities unless given a velocity distribution function. There are ways to connect these things within plasma physics.
Post Reply

Return to “Images du Jour”