Friday, July 30, 2010
Saturday, July 3, 2010
It feels nice to be writing again. Since my last update I have acquired a 75kV x-ray transformer, as well as all the parts to make my vacuum chamber. I also got a Veeco EP-2A air cooled diffusion pump. Inconveniently, both this pump and my HV feedthrough require custom flanges to be machined. The plans for my new chamber are below.
In the plans, the HV feedthrough port is the lower left one, the diffusion pump port is the bottom middle one, and the long one on the bottom right is an ion gun based on a DC magnetron, which is not shown. The DC magnetron is unlike it's cousin, the cavity magnetron, which creates microwaves, whereas the DC magnetron helps ionize gas by setting electrons into a spiraling path. Inside the source, there will be a 6"x1/4" rod charged to 3-5 kV. The magnets will surround the source partially, or I will use a large electromagnet wound around the source.. The 30kV will be generated by a 15kV NST (floating center tap) run through a voltage doubler constructed of microwave oven capacitors and diodes.
I have also decided that I will leak deuterium into the chamber through a 5 micron wide orifice on the ion gun. The deuterium will first be regulated down to 5 psi from tank pressure by a hydrogen regulator, and then it will pass through the 5 micron orifice and through a ball valve.
To detect neutrons, I will be using a much cheaper approach than the normal bubble dosimeter or a He-3 or B-10 tube. I will be using a cloud chamber to view proton recoil from neutrons as they pass through a hydrogenous moderator. The chamber will be lead shielded, allowing only strong cosmic rays and neutrons to pass into it. There will be a piece of LDPE inside the chamber to allow for the proton recoil to occur. Below is a picture of proton recoil tracks in a cloud chamber.