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Re: Jan Ruge Fusion Attempt @ Chaos Darmstadt

Posted: Thu Oct 11, 2018 10:14 am
by Dennis P Brown
I too went this route, at first. I too learned a great deal.

I even built a 100 kV voltage supply, and achieved the low 10^-6 torr, and built the ion accelerator with gun (I built various van de graaf'fs, all to no avail. Talk about a waste of time - lol.) I stopped when I realized that the voltage multiplier power supply was simply far too dangerous. I started to build a shield system but realized this wasn't a system I even wanted to have on while operating so I decided to break it down and store it.

Instead, when a proper transformer became available to me for free (I have recently returned it to its owner), I built a conventional fusor and created neutrons. I still have the lethal voltage multiplier and ion gun assembly w/turbo station in my den. Haven't convinced myself not to return to it just to see if I get neutrons from it (I have a deuterium loaded target and of course, deuterium gas) but not certain it would buy me anything, really. I have already done fusion and not really interested in other targets (the energy is too low to really activate much.)

Re: Jan Ruge Fusion Attempt @ Chaos Darmstadt

Posted: Thu Oct 11, 2018 4:36 pm
by Richard Hull
60hz multipliers suffer from the need to have larger capacitances, (dangerous energy storage), to have significant current capability. High frequency multipliers do far better with lower stored energy capacitors. Unfortunately the initial high voltage transformer is typically weak and not capable of the 600+ watts needed to do easily detectable fusion. These usually take the form of a modified flyback transformer or one of the "beefy" Accel automotive ignition coils. Ultimately, a larger, custom wound ferrite transformer is needed for an HF supply.

Lucky finds await the person with patience. Custom HF, HV supplies come onto e-bay on. Occasionally, local or ham-fest, 60hz x-ray transformers, while rare, are also a possibility.

The possibility of finding the right polarity supply complicates the issue tremendously. (positive grounded-negative hot) This latter requirement foils most really nice HF supplies with potted multipliers.

Neutron detection and the power supply needed to do fusion are among the most difficult items to obtain on the amateur's way to successful fusion.

Richard Hull

Re: Jan Ruge Fusion Attempt @ Chaos Darmstadt

Posted: Sun Oct 14, 2018 7:33 pm
by Jan Ruge
Thanks for your positive response, yes, we have definitely learned a lot.

"As empirical results have shown, our high voltage supply is not lethal" To be honest: while adjusting a spark gap it arced through the handle of a heavy duty screwdriver into my hand... Unless you are paranoid, Murphy's law will get you... The cascade consists of 20 x 2.2nF capacitors, therefore the maximum stored energy is at max. 20*0.5*20kV^2 * 2.2nF = 8.8J. This accident happened at roughly 50kV so just ~0.6J, but definitely painful.

We have measured all the components with an LCR meter, so we have a quite accurate simulation. Here are a close-up and the schematic. I've also attached the .asc (LTSpice IV file) so you can run your own simulation. This helped us a lot for the understanding of this circuit. The IRFZ44N (55V/49A) will die at 15V due to the high voltage of the L2L3C1 resonant circuit and are now replaced with IRFP140N (100V/33A). I guess one of those 1kW ZVS induction heater modules from eBay/Amazon would also work fine, but we haven't reverse engineered one yet.
An X-Ray transformer would be nice, but we would need a permanent setup and more space. We are quite happy with our current supply. As we do not need to maintain a giant fusor plasma and in theory could suppress the electrons emitted by the target, we hopefully require less power. Time will tell...

Re: Jan Ruge Fusion Attempt @ Chaos Darmstadt

Posted: Mon Oct 15, 2018 2:23 pm
by Dennis P Brown
It is rather important that you do "suppress" electrons from off the target using reverse biasing (this can be a challenge with your high voltage target - that is why I "grounded" my target relative to the gun so biasing was easy*.) The potential x-ray flux can be quit dangerous (electron's tend to be created in large numbers from a target undergoing ion bombardment) and voltages above 30 kV in this type of device is certainly of concern even if the beam current is low.

In any case, shielding between the operator and the proton gun assembly is a good idea to be on the safe side.

Current from the ion gun and hence neutron flux or gamma ray output (depending on your goal) from the target are directly related in these devices; hence my hyper (very lethal) power supply since I wanted an easy to detect neutron source (lots of deuterium ions generated.) Detection of the gamma ray's might be more difficult then neutrons but is an interesting idea and your approach appears to have been thought out but you might need a number of runs to prove it is 'creating' fusion.

Aside: glad you haven't given up on an ion gun (like someone here who happens to be posting this comment) and I look forward to your posts here and wish you success. Another aside - creating a viable gamma ray signal is not going to be easy, I'd think - especially from D-D fusion events. Back ground cosmic rays will likely exceed your signal so long runs to get a 'clean' signal from the background might be necessary to prove you have fusion.

*My deuterium gun was battery powered to ionize the gas and "floated" inside a steel hemisphere that was charged to 100kV positive. My potential x-ray flux would have been of great concern if I hadn't bias my target. Your method is certainly better suited for high voltage safety as long as your vacuum housing near the HV input is well grounded. Your system performance will be better at the lowest possible vacuum - achieving the low 10^-6 torr is a good goal.