Here we go again, this is the last one I promise (fingers crossed).
Starting a new thread for my next build called FICS II. FICS stands for Fusion Induced Charge Separation, more later. FICS II is in the very early planning stages and I estimate it might take at least a year to build. As you will soon see there are some complex engineering challenges I need to be overcome, and some of the parts are not cheap, so it will happen slowly.
The oldies in this group know my fascination with hollow cathode reactors, but for the new members I summarise a brief history of my past successes and failures.
--------- History of Steven's Hollow Cathode Reactors 2005-2015 -----------
STAR-1 was my first build, it looked like a fusor but was not a standard fusor, inside the spherical chamber was a hollow cathode with diametrically opposing ceramic tubes (seen protruding from the top), the cavity between the outer shell and the inner shell was filled with dielectric oil. Although it produced a small amount of fusion in the 1 x 10^5 or there about, it soon failed due to leaks between the ceramic accelerator tubes and the nylon Swagelok fittings I used, so this design needed a rethink. At least I learned a lot about high voltage and vacuum technology with this one.
STAR-2, also a hollow cathode reactor had a number of improvements, first it was built in a transparent oil tank with a cage replacing the anode, it solved the leak issue by replacing the ceramic tubes with glass tubes, the glass tubes were custom made to fit a standard KF25 flange and O ring. In addition to the improved accelerator tubes this version was fitted with a negative ion source (seen on top). STAR-2 was quite successful it produced neutrons in the 2.5 x 10^5 range but it was temperamental and used to spit fire like an angry dragon. I believe was caused by fast ions going to ground causing a build up of negative charge on the cathode, this charge would be released up the tube causing s sudden flash with more ionisation. This one also blew up my PSU twice, even though it had a ballast resistor and overload protection, I believe it may have been negative charge build up on the cathode which led to this. Eventual failure on this one was again a brown conductive build up inside the glass tubes which I learnt was due to sputtering.
STAR-3, was an attempt at focusing the beam using some copper dynodes and longer glass tubes, it was a disaster and I don't recall ever measuring any neutrons from it. Anyhow it had a different geometry with a smaller anode and used less oil so it was a better design.
STAR-4, by the time I got around to building STAR-4, I had already made a lot of the obvious mistakes, it was a more compact build and was designed to be easy to open and service. Again it was a hollow cathode with glass tubes and ion source fitted to the top. With this reactor we had some good neutron runs and we also observed a very strange phenomenon where the reactor would keep running ie. visible plasma, neutron counts and x-rays, after the HV power was switched off, not for a couple of seconds, but up to 10 minutes or more providing the negative ion source was left on. This may be the first over unity ever constructed, who knows, in any case it has been the subject of my thoughts for a long time, as I really wanted to understand what crazy stuff was going on.
FICS-1, after pondering about the strange run on effect with STAR 4, I eventually started to understand what was going on, the deuterium ions would fuse and send the positively charged He particle to ground, thereby leaving a negative charge on the hollow cathode, this tiny amount of charge exchange was enough to maintain several tens of kV on the cathode, especially since the cathode was under oil with minimal current leakage, even a few micro coulomb can charge a tiny spherical cathode with a capacitance in the pico Farad range. So I designed a reactor to take advantage of this effect, and called it FICS. In the image below you can see the reactor running with a nice plasma inside. FICS-1 was a single ended hollow cathode reactor constructed from glass and aluminium discs. It had a hollow tungsten cathode with the deuterium supply floating at cathode potential (very important for the charge exchange process). This was a very nice build, the glass and aluminium construction method was a great success, and everything looked quite promising. I did a couple of runs, and measured plenty of neutrons, but unfortunately it soon became evident when I reached a certain voltage, it would emit a huge amount of x-rays, so I had to stop running it. I took it apart to investigate where the electrons where coming from and I discovered a brown burn mark on the steel flange at ground potential where the electrons had taken an unexpected shortcut to ground. These are the risks you take when doing stuff others haven't done before, which is why one should impose double safety measures when treading an unknown path.
FICS-2, is my next project, I confidently think I have it all worked out (tongue in cheek), this one is going to be the first reactor to run on it's own power. It will be a double ended hollow cathode reactor constructed using the previously used glass and aluminium disc method. Aluminium has been chosen as the optimum material in both the cathode and the dynode discs both for it's price, ease of machining and low Z. Once again the gas supply will be floating at cathode potential and fed directly into the cathode. The only source of ionisation will paschen breakdown and ions traversing through the hollow cathode, and once some fusion reactions start there will be more ionisation caused by the heat. I believe I have now solved the problem of charge build up on the cathode, the electrons will have an escape to ground via an array of zener diodes when/if the cathode voltage exceeds a given threshold. Negative high voltage will not be supplied directly to the cathode but will be applied to dynode 9, so some ions will be accelerated from GND to D9 where they will be injected into the cathode cavity and cause more ionisation and the occasional fusion reaction inside the cathode, the reactions which take place inside the cathode will cause an alpha particle to either hit the inside wall and generate secondary electrons or pass through the hole and go to ground. Every alpha particle going to ground contributes to a negative charge on the cathode. Given enough alpha particles make it to ground, the reactor will self sustain.
Problems solved in FICS-II
Laminating the discs together with Latex is a tricky and time consuming job, and does not leave much room for mistakes, but it worked in FICS-1 and I hope it works again now.
Each aluminium disc will be machined on a CNC lathe so it overlaps the adjoining discs without touching, this prevents the ions in the tube from hitting the inside of the glass disc.
Firstly the use of Aluminium with low Z reduces the energy of the x-rays, in addition to this the electrons generated inside the cathode will not be able to enter the tube, as dynode 9 will be stepped down to a lower voltage than the zener escape.
Possible new problems in FICS-II
Floating the deuterium gas and regulator
This will be a challenge because any kind of mass flow controller or regulator needs power, which will have to be supplied by a floating battery.
For safety reasons this reactor needs to be operated remotely, this involves building a control panel which not only controls the power but also the pressure and the gas. Controlling a floating mass flow controller is going to require some kind of servo or fibre optic control, something I have no current experience with.
This is already looking like the most expensive build so far, and one can only take so much out of the household budget these days, so I hope the Gammaspectacular business will continue funding my fusion research as it has been doing, so far so good.
Intellectual Property Protection
Yes if it works someone will copy the idea and run with it, but unfortunately copying is going to happen regardless of weather you have a patent or not, the only difference is you have the right to sue, and you have to ask yourself if you want to spend your life in the lab or in a court room. I wasted tens of thousands of dollars on patent protection in the past, and it's a mugs game, the legal costs and challenges start long before a patent is granted. My hollow cathode concept has already been copied once, by a company developing a neutron source, I feel privileged and take it as a complement my design was worth copying.
More to follow...
As this project matures I will append the progress reports to this thread, and if anyone has any advise or suggestions please let me know.