Page 1 of 1

Preparing for fusion

Posted: Tue Apr 24, 2012 11:39 pm
by fpg
It has been a while since I posted anything on this forum, the project has been on hold for the past year partly due to my participation in the international young physicists´ tournament and my recently started physics studies at the university.

Anyway I have made great progress since my last post as can be seen in the pictures below, the fusor was finished just before the summer, a time when several experiments were made, by then I observed the first plasma inside the new chamber. I was using nothing more than my old nst and realized that I needed a bit more power. I decided that the cheapest (and the only available) alternative for more power was to build a powersupply made out of three medium sized flyback transformers powered by a single ZVS driver. Although not the most reliable powersource it was still way better than the nst, capable of delivering up to 25kV 10mA albeit not for long timeperiods. I have currently changed the triple transformer arrangement to a single large flyback rated at 40kV 20mA, i have reached 30kV 12mA with no observable problems so far. Although this supply might not be best, it will have to do until I find a better option.

Shortly after receiving the large flyback transformer I started working on the gas inlet system for the deuterium supply. I decided that the cheapest way for me to introduce deuterium into the chamber was to use the electrolysis method. I created a crude electrolysis system (barely seen in the first picture) and did some tests with ordinary water before receiving some purified heavy water from the nuclear physics department for free . Not surprisingly due to the lack of quality hoses and sterile equipment I suspected there was a lot of impurities, which improved a bit after adding the drying stack judging from the look of the plasma.

I have done some experiments with air, protium and deuterium inside the chamber and I have observed a stable plasma with the so called “star mode” as can be seen in the second picture with deuterium introduced into the chamber. The voltage was around 23kV with 9mA of current. In the last picture with air in the chamber the voltage was 28kV with 12mA.

I have asked the nuclear physics department if they could lend me a neutron detector and they told me that due to legal issues they could only lend me a detector if I moved the reactor to their department which is a bit problematic. I did try neutron activation using a piece of silver foil but the results were poor. The closest thing to a neutron detector I currently have is the well known cheap corona counter SNM-9 bought on ebay. Sadly I haven’t had much luck with the circuit powering the counter so far.

My current hope lies in buying a classical BTI detector but BTI doesn´t seem to sell to a single individual therefore I`m wondering if there is anyone else who is planning on buying a bubble counter, if so then I would like to join.

There is still a little bit of tweaking left to do and a gap left to be filled by a neutron detector before I do the real fusion experiment, but it seems that the goal hopefully isn´t that far away.

// Fredrik Parnefjord Gustafsson

Re: Preparing for fusion

Posted: Wed Apr 25, 2012 2:51 pm
by Richard Hull
Fredrik, this is a great looking fusor! I am fairly sure you are doing fusion, but you really need to get either a counter or a bubble detector, as you note.

Silver activation usually occurs in a well worked fusor at about 30kv @ 10ma. This should produce a level of silver isotope that you can easily detect with a GM counter. You will have to be very fast as the count falls off very fast over the first minute or so after removing from the moderator.

Make sure to report on your neutron findings. I hope to soon place you in the Neutron club once you have a neutron report for us. You are already in the Plasma club.

Keep up the fine effort.

Richard Hull